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Cell Stress (cell + stress)
Selected AbstractsThe liver stage of Plasmodium berghei inhibits host cell apoptosisMOLECULAR MICROBIOLOGY, Issue 3 2005Claudia Van De Sand Summary Plasmodium berghei is the causative agent of rodent malaria and is widely used as a model system to study the liver stage of Plasmodium parasites. The entry of P. berghei sporozoites into hepatocytes has extensively been studied, but little is known about parasite,host interaction during later developmental stages of the intracellular parasite. Growth of the parasite far beyond the normal size of the host cell is an important stress factor for the infected cell. Cell stress is known to trigger programmed cell death (apoptosis) and we examined several apoptotic markers in P. berghei -infected cells and compared their level of expression and their distribution to that of non-infected cells. As none of the apoptotic markers investigated were found altered in infected cells, we hypothesized that parasite infection might confer resistance to apoptosis of the host cell. Treatment with peroxide or serum deprivation induced apoptosis in non-infected HepG2 cells, whereas P. berghei -infected cells appeared protected, indicating that the parasite interferes indeed with the apoptotic machinery of the host cell. To prove the physiological relevance of these results, mice were infected with high numbers of P. berghei sporozoites and treated with tumour necrosis factor (TNF)-,/d -galactosamine to induce massive liver apoptosis. Liver sections of these mice, stained for degraded DNA, confirmed that infected cells containing viable parasites were protected from programmed cell death. However, in non-treated control mice as well as in TNF-,-treated mice a small proportion of dead intracellular parasites with degraded DNA were detected. Most hepatocytes containing dead parasites provoked an infiltration of immunocompetent cells, indicating that these cells are no longer protected from cell death. [source] The role of autophagy in , -cell lipotoxicity and type 2 diabetesDIABETES OBESITY & METABOLISM, Issue 2010G. Las Autophagy, a ubiquitous catabolic pathway involved in both cell survival and cell death, has been implicated in many age-associated diseases. Recent findings have shown autophagy to be crucial for proper insulin secretion and , -cell viability. Transgenic mice lacking autophagy in their , -cells showed decreased , -cell mass and suppressed glucose-stimulated insulin secretion. Several studies showed that stress can stimulate autophagy in , -cells: the number of autophagosomes is increased in different in vivo models for diabetes, such as db/db mice, mice fed high-fat diet, pdx-1 knockout mice, as well as in in vitro models of glucotoxicity and lipotoxicity. Pharmacological and molecular inhibition of autophagy increases the susceptibility to cell stress, suggesting that autophagy protects against diabetes-relevant stresses. Recent findings, however, question these conclusions. Pancreases of diabetics and , -cells exposed to fatty acids show accumulation of abnormal autophagosome morphology and suppression of lysosomal gene expression suggesting impairment in autophagic turnover. In this review we attempt to give an overview of the data generated by others and by us in view of the possible role of autophagy in diabetes, a role which depending on the conditions, could be beneficial or detrimental in coping with stress. [source] Indications for cell stress in response to adenoviral and baculoviral gene transfer observed by proteome profiling of human cancer cellsELECTROPHORESIS, Issue 11 2010Christopher Gerner Abstract Gene transfer to cultured cells is an important tool for functional studies in many areas of biomedical research and vector systems derived from adenoviruses and baculoviruses are frequently used for this purpose. In order to characterize how viral gene transfer vectors affect the functional state of transduced cells, we applied 2-D PAGE allowing quantitative determination of protein amounts and synthesis rates of metabolically labeled cells and shotgun proteomics. Using HepG2 human hepatoma cells we show that both vector types can achieve efficient expression of green fluorescent protein, which accounted for about 0.1% of total cellular protein synthesis 72,h after transduction. No evidence in contrast was found for expression of proteins from the viral backbones. With respect to the host cell response, both vectors induced a general increase in protein synthesis of about 50%, which was independent of green fluorescent protein expression. 2-D PAGE autoradiographs identified a 3.6-fold increase of ,-actin synthesis in adenovirus transduced cells. In addition shotgun proteomics of cytoplasmic and nuclear extract fractions identified a slight induction of several proteins related to inflammatory activation, cell survival and chromatin function by both virus types. These data demonstrate that commonly used gene transfer vectors induce a response reminiscent of stress activation in host cells, which needs to be taken into account when performing functional assays with transduced cells. [source] Haemodialysis induces mitochondrial dysfunction and apoptosisEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 12 2007D. S. C. Raj Abstract Background Mitochondria play a crucial role in the regulation of the endogenous pathways of apoptosis activated by oxidant stress. Nuclear factor-,B (NF-,B) is a central integration site for pro-inflammatory signals and oxidative stress. Materials and methods Peripheral blood mononuclear cells (PBMC) were isolated from eight end-stage renal disease (ESRD) patients before haemodialysis (Pre-HD) and during the last 10 min of HD (End-HD). A new polysulfone membrane (F70, Fresenius) was used for dialysis. Intracellular generation of reactive oxygen species (ROS), mitochondrial redox potential (,,m) and PBMC apoptosis were determined by flow-cytometry. Results Plasma levels of interleukin-6 (IL-6) (24·9 ± 7·0 vs. 17·4 ± 5·5 pg dL,1, P < 0·05), IL-6 soluble receptor (52·2 ± 4·9 vs. 37·6 ± 3·2 ng dL,1, P < 0·02) and IL-6 gp130 (405·7 ± 41·0 vs. 235·1 ± 38·4 ng dL,1, P < 0·02) were higher end-HD compared to pre-HD. IL-6 secretion by the isolated PBMC (24·0 ± 2·3 vs. 19·3 ± 3·5 pg dL,1, P < 0·02) increased end-HD. Percentage of lymphocytes exhibiting collapse of mitochondrial membrane potential (43·4 ± 4·6% vs. 32·6 ± 2·9%, P < 0·01), apoptosis (33·4 ± 7·1% vs. 23·7 ± 7·7%, P < 0·01), and generation of superoxide (20·7 ± 5·2% vs. 12·5 ± 2·9%, P < 0·02) and hydrogen peroxide (51·1 ± 7·8% vs.38·2 ± 5·9%, P < 0·04) were higher at end-HD than pre-HD. NF-,B activation (3144·1 ± 208·1 vs. 2033·4 ± 454·6 pg well,1, P < 0·02), expression of B-cell lymphoma protein-2 (6494·6 ± 1461 vs. 3501·5 ± 796·5 ng mL,1, P < 0·03) and heat shock protein-70 (9·81 ± 1·47 vs. 6·38 ± 1·0 ng mL,1, P < 0·05) increased during HD. Conclusions Intra-dialytic activation of cytokines, together with impaired mitochondrial function, promotes generation of ROS culminating in augmented PBMC apoptosis. There is concomitant activation of pathways aimed at attenuation of cell stress and apoptosis during HD. [source] Cytochrome c oxidase isoform IV-2 is involved in 3-nitropropionic acid-induced toxicity in striatal astrocytesGLIA, Issue 14 2009Shilpee Singh Abstract Astrocyte mitochondria play an important role for energy supply and neuronal survival in the brain. Toxic and degenerative processes are largely associated with mitochondrial dysfunction. We, therefore, investigated the effect of 3-nitropropionic acid (NPA), a mitochondrial toxin and in vitro model of Huntington's disease (HD), on mitochondrial function and viability of primary striatal astrocytes. Although NPA is known as an irreversible inhibitor of succinate dehydrogenase, we observed an increase of astrocyte ATP levels after NPA treatment. This effect could be explained by NPA-mediated alterations of cytochrome c oxidase subunit IV isoform (COX IV) expression. The up-regulation of COX isoform IV-2 caused an increased enzyme activity at the expense of elevated mitochondrial peroxide production causing increased cell death. The application of a small interfering RNA against COX IV-2 revealed the causal implication of COX isoform IV-2 in NPA-mediated elevation of oxidative stress and necrotic cell death. Thus, we propose a novel, additional mechanism of NPA-induced cell stress and death which is based on structural and functional changes of astrocyte COX and which could indirectly impair neuronal survival. © 2009 Wiley-Liss, Inc. [source] Regulation of the immune response by stress-activated protein kinasesIMMUNOLOGICAL REVIEWS, Issue 1 2009Mercedes Rincón Summary:, Activation of immune cells to mediate an immune response is often triggered by potential ,danger' or ,stress' stimuli that the organism receives. Within the mitogen-activated protein kinases (MAPKs) family, the stress-activated protein kinase (SAPK) group was defined as group of kinases that activated by stimuli that cause cell stress. In the immune cells, SAPKs are activated by antigen receptors (B- or T-cell receptors), Toll-like receptors, cytokine receptors, and physical,chemical changes in the environment among other stimuli. The SAPKs are established to be important mediators of intracellular signaling during adaptive and innate immune responses. Here we summarize what is currently known about the role of two sub-groups of SAPKs , c-Jun NH2 -terminal kinase and p38 MAPK-in the function of specific components of the immune system and the overall contribution to the immune response. [source] Bacterial dormancy in Campylobacter: abstract theory or cause for concern?INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2001John E. Moore For the past 100 years, since the birth of modern microbiology, this discipline has predominantly relied on the ability to culture micro-organisms in vitro on artificial synthetic culture media under controlled conditions in the laboratory. However, sometimes it is not possible to detect foodborne pathogens using such conventional techniques. Employment of these techniques can also lead to a delay in detection of pathogens. The ,viable but non-culturable' (VNC) cellular form has been demonstrated in Campylobacter jejuni, representing a resting or dormant stage, which is induced through cell stress including starvation. This form is extremely difficult to detect and generally requires complex and sophisticated technology which is usually not available in most routine food microbiology laboratories. This review aims at examining the role of this cell form in Campylobacter, including their historical evolution, formation, physiology, detection and to discuss the challenges that this form presents to food safety. [source] Translational regulation in cell stress and apoptosis.JOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 3 2001Roles of the eIF4E binding proteins Abstract Several mechanisms have been identified by which protein synthesis may be regulated during the response of mammalian cells to physiological stresses and conditions that induce apoptotic cell death (reviewed in Clemens et al., Cell Death and Differentiation 7, 603,615, 2000). Recent developments allow us to up-date this analysis and in this article I concentrate on one particular aspect of this regulation that has not previously been reviewed in depth in relation to apoptosis, viz. the control of the initiation of protein synthesis by eukaryotic initiation factor eIF4E and the eIF4E binding proteins (4E-BPs). Changes in the state of phosphorylation of the 4E-BPs and in the extent of their association with eIF4E occur at an early stage in the response of cells to apoptotic inducers. The review discusses the mechanisms by which these events are regulated and the significance of the changes for the control of protein synthesis, cell proliferation and cell survival. [source] Proliferation and differentation markers in snuff-induced oral mucosal lesionsJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 5 2002Marina Merne Abstract Background: Regular use of snuff is known to cause whitish oral mucosal lesions of variable severity at the usual quid placement site. The main aim of this study was to elucidate cellular mechanisms involved in snuff-induced epithelial changes. Methods: Expression patterns for markers of cell proliferation (PCNA, Ki-67), cell cycle regulation (p53, p21), keratin changes (pankeratin, CK18, CK19), cell stress (HSP 70) and collagen type IV in 14 snuff-induced oral mucosal lesions and 12 control samples were analyzed by immunohistochemistry (IHC). Results: On light microscopy, all snuff-induced lesions were characterized by a hyperkeratinized and thickened epithelium. Some vacuolized cells, markers of cell degeneration, were frequently seen (in 9/14 of the samples) in the superficial layers in epithelia. Expression of PCNA and Ki-67 was found in a statistically significantly fewer cells in snuff-induced lesions (P < 0.001) than in the controls. This indicates that epithelia in snuff-induced lesions are not thickened as a result of increased cellular proliferation, but by protracted turnover of differentiating cells. Of cell cycle markers, p21 was found be up-regulated in 4/14 snuff-induced lesions, probably by p53-independent pathways. Only two snuff-induced lesions showed p53 positivity. However, the number of stained cells with p53 and p21 was not statistically different from that in controls. Expression of CK18, but not any alterations in CK19 expression, was seen in 5 of 14 snuff-induced lesions. Snuff also seems to stimulate the expression of collagen type IV, possibly by basal cells, as indicated by the thickened staining of the basal lamina. Conclusions: The findings of this study showing suppressed cellular proliferation and infrequent p53 dysfunction in snuff lesions may partly explain why dysplastic changes are seldom seen in mucosal lesions induced by the Scandinavian type of snuff. [source] Influence of implantation interval on the long-term biocompatibility of surgical meshBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 8 2002Dr B. Klosterhalfen Background: The aim was to study the long-term tissue response to polypropylene mesh. Methods: This was a retrieval study that investigated 76 polypropylene meshes with a median implantation interval of 18 (range 2,180) months. Mesh was explanted following hernia recurrence, infection or pain. The median implantation interval was 20 (range 4,180) months in the recurrence group, 30 (range 5,48) months in the pain group and 10 (range 2,56) months in the infection group (P < 0·05, infection versus pain or recurrence). The inflammatory response was determined by immunohistochemistry of macrophages (CD68), polymorphonuclear granulocytes (CD15) and T and B lymphocytes (CD3 and CD20). The cell turnover within the interface mesh fibre,recipient tissue was measured by TUNEL for apoptosis or DNA strand breaks, Ki67 for cell proliferation and heat-shock protein (HSP) 70 for cell stress. Results: With the exception of HSP-70, levels of all variables decreased over time. Sex, age, type of previous operation or location of the mesh did not have a significant influence. Conclusion: Long-term incorporated polypropylene mesh in humans has a more favourable tissue response with increasing implantation interval. © 2002 British Journal of Surgery Society Ltd [source] | |||||||||||||