Home About us Contact
|
Home About us Contact | ||
|
|
||
Oxidative Burst (oxidative + burst)
Kinds of Oxidative Burst Selected AbstractsEVIDENCE OF A LATENT OXIDATIVE BURST IN RELATION TO WOUND REPAIR IN THE GIANT UNICELLULAR CHLOROPHYTE DASYCLADUS VERMICULARIS,JOURNAL OF PHYCOLOGY, Issue 3 2005Cliff Ross We investigated the kinetics and composition of the second phase of the wound repair process of Dasycladus vermicularis ([Scropoli] Krasser) using fluorescent probes, chromatography, UV spectroscopy, and histochemistry. Our new evidence supports the hypothesis that the second phase of wound repair (initiated at approximately 35,45 min postinjury) is based on the activation of an oxidative burst that produces micromolar H2O2 levels. These results provide evidence of peroxidase activity at the wound site, real-time measurements of an oxidative burst, and catechol localization in wound plugs. Strong evidence is presented indicating that the biochemical machinery exists for oxidative cross-linking to ensue in the wound-healing process of D. vermicularis. [source] Oxidative Burst in Suspension Culture of Taxus cuspidataInduced by a Laminar Shear Stress in Short-TermBIOTECHNOLOGY PROGRESS, Issue 2 2004Rong-Bin Han Generation of active oxidative species induced by shear stress in suspension cultures of Taxus cuspidata was investigated in a Couette-type shear reactor. It was found that T. cuspidata cells respond to a shear rate of 95 s,1 with oxidative bursts. Their triphasic characteristics in 6 h were similar in both intracellular H2O2 production and extracellular O2,, production. Additionally, inhibition studies with diphenylene iodonium and azide suggested that the key enzyme responsible for oxidative bursts under the shear rate of 95 s,1 is primarily NADPH oxidase and the contribution of peroxidase for oxidative bursts was less. Investigation of the relationship between active oxidative species and defense responses induced by the shear stress indicated that the O2,, burst may account for the change of membrane permeability, and the H2O2 burst plays an important role in inducing secondary metabolites such as the activation of phenylalanine ammonia lyase enzyme and phenolic accumulation. Furthermore, oxidative bursts elicited by the shear rate of 95 s,1 were suppressed by treatment with suramin, nifedipine, and neomycin prior to the shear stress treatment, suggesting that G-protein, Ca2+ channel, and phospholipase C are involved in the signal pathway for oxidative bursts induced by the shear stress. A model is proposed to explain the oxidative burst in cultured T. cuspidata cells challenged with the shear stress. [source] Dietary exposure to low pesticide doses causes long-term immunosuppression in the leopard frog (Rana pipiens)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2007Anathea Albert Abstract This study examines the relationship between dietary exposure of pesticides, DDT, and dieldrin and immunosuppression in the northern leopard frog (Rana pipiens). Immune function was measured before, during, and after a 10-week exposure period with the use of both adaptive and innate immunity responses. Exposure to low doses (75 ng/g body wt DDT or 2.1 ng/g dieldrin total dose over the 10 weeks) resulted in significant suppressive effects on antibody production and secondary delayed-type hypersensitivity (DTH). The high doses (750 ng/g DDT and 21 ng/g dieldrin), however, did not affect antibody production, DTH, or oxidative burst in a predictable dose,response manner. The differences in magnitude and direction of the effects of the two dosing regimes were likely due to differences in chemical exposure on the basis of feeding and effectiveness of chemical uptake. The low dose results demonstrated that moderate concentrations of pesticides, frequently observed in the environment, are able to weaken the immune response of R. pipiens. [source] Granulocyte function in patients with L-ferritin iron-responsive element (IRE) 39C,T-positive hereditary hyperferritinaemia,cataract syndromeEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 10 2004R. Fritsche-Polanz Abstract Background, Hereditary hyperferritinaemia,cataract syndrome (HHCS) is an autosomal dominant trait associated with mutations in the iron responsive element (IRE) of the ferritin light-chain (L-ferritin) gene. Patients typically show elevated serum ferritin concentrations without iron overload and a bilateral cataract. Hyperferritinaemia can be associated with granulocyte dysfunction in patients with thalassemia beta and in haemodialysis patients. The effect of increased L-ferritin levels on granulocyte function in patients with HHCS is unknown. Material and methods, We examined glucose uptake, oxidative burst, chemotaxis, phagocytosis, apoptosis and intracellular calcium concentrations in polymorphonuclear leucocytes (PMNLs) of five affected members of a family with HHCS and in five healthy individuals matched for age and gender. Results, Mutation testing revealed a 39C,T transition in IRE in all five patients with HHCS. Serum ferritin levels of patients ranged between 907 and 2030 µg L,1, respectively. In comparison with healthy individuals, PMNLs of patients with HHCS showed a significant increase in PMA-mediated stimulation of the oxidative burst, as well as a significantly higher stimulation of glucose uptake but no difference with respect to chemotaxis, phagocytosis, apoptosis and intracellular calcium concentrations. Conclusion, In summary, our study suggests that hyperferritinaemia in patients with IRE 39C,T-positive HHCS is associated with activation of PMNLs but not with disturbance of fundamental PMNL function. [source] Dysregulation of monocyte oxidative burst in streptococcal endocarditisEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 10 2001E. Presterl Background Streptococcal subacute endocarditis is characterized by low-grade systemic inflammation. Although structural cardiac defects are pivotal, phagocytic cells, i.e. monocytes and neutrophils, are involved in the induction and the course of bacterial endocarditis. Decreased production of reactive oxygen metabolites was described in long-lasting infections. We hypothesized that the oxidative burst of phagocytes induced by the infecting organism is defective in patients with streptococcal endocarditis. Patients and methods The monocytes and neutrophils of 11 patients with streptococcal native valve endocarditis were challenged with the respective pathogens and two control streptococcal strains, and the oxidative burst was determined by fluorescence-activated cell sorter analysis. These experiments were done before any antibiotic therapy was administered, and repeated at least 12 months after recovery. Eight volunteers served as healthy controls. Results The monocyte response to the respective pathogens was decreased in the patient groups compared to the response to the control streptococci. After cure the monocyte response to the pathogens was not different to the response to the control strains. The monocyte response of the healthy volunteers did not show any differences between the patients' pathogens and the control strains. The neutrophil oxidative burst to the pathogens was similar to that to the control streptococci in both patient and the volunteer group. Conclusion The decreased response of patient monocytes to the pathogens may contribute to the low-grade inflammatory response and to the course of streptococcal endocarditis. [source] TREM-1 promotes survival during septic shock in miceEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2007Sébastien Gibot Dr. Abstract Triggering receptor expressed on myeloid (TREM)-1 is integral to the inflammatory response occurring during septic shock, although its precise function has yet to be determined. Here we show that in vivo silencing of TREM-1 using siRNA duplexes in a fecal peritonitis mouse model resulted in a blunted inflammatory response and increased mortality. This was associated with impaired bacterial clearance related to marked inhibition of the neutrophil oxidative burst. By contrast, TREM-1 -silenced mice were highly resistant to a lethal endotoxin challenge, while partial silencing of TREM-1 in the bacterial peritonitis model produced a significant survival benefit. These data highlight the crucial role of the TREM-1 pathway in mounting an adequate inflammatory and cytotoxic response to polymicrobial sepsis, and both the therapeutic promise and potential risks of its modulation. [source] Novel ,-1,3-, 1,6-oligoglucan elicitor from Alternaria alternata 102 for defense responses in tobaccoFEBS JOURNAL, Issue 11 2006Tomonori Shinya A novel elicitor that induces chitinases in tobacco BY-2 cells was isolated from Alternaria alternata 102. Six other fungi, including A. alternata IFO 6587, could not induce, or weakly induce chitinase activity. The purified elicitor was soluble in 75% methanol and showed the chitinase-inducing activity when applied at concentrations of as low as 25 ng·mL,1. Structural determination by methylation analysis, reducing-end analysis, MALDI-TOF/MS, and NMR spectroscopy indicated that the elicitor was a mixture of ,-1,3-, 1,6-oligoglucans mostly with a degree of polymerization of between 8 and 17. Periodate oxidation of the elicitor suggested that the 1,6-linked and nonreducing terminal residues are essential for the elicitor activity. Further analysis of the elicitor responses in BY-2 cells indicated that the activity of this ,-1,3-, 1,6-glucan elicitor was about 1000 times more potent than that of laminarin, which is a known elicitor of defense responses in tobacco. Analyzing the expression of defense-related genes indicated that a phenylalanine ammonia-lyase gene and a coumaroyl-CoA O -methyltransferase gene were transiently expressed by this ,-1,3-, 1,6-glucan elicitor. The elicitor induced a weak oxidative burst but did not induce cell death in the BY-2 cells. In the tissue of tobacco plants, this ,-1,3-, 1,6-glucan elicitor induced the expression of basic PR-3 genes, the phenylpropanoid pathway genes, and the sesquiterpenoid pathway genes. In comparison with laminarin and laminarin sulfate, which are reported to be potent elicitors of defense responses in tobacco, the expression pattern of genes induced by the purified ,-1,3-, 1,6-glucan elicitor was more similar to that induced by laminarin than to that induced by laminarin sulfate. [source] Accumulation of deoxynivalenol and its 15-acetylated form is significantly modulated by oxidative stress in liquid cultures of Fusarium graminearumFEMS MICROBIOLOGY LETTERS, Issue 1 2006Nadia Ponts Abstract Liquid cultures of Fusarium graminearum were supplemented with H2O2 or other oxidative compounds. The accumulation kinetics of the resulting trichothecenes were monitored. At non-lethal concentrations, the H2O2 treatments modulated toxin accumulation, dependent on the method of supplementation. When H2O2 was added at the same time as the inoculation, higher levels of toxins accumulated 30 days later. Conversely, adding H2O2 2 or 7 days after inoculation had little effect. When H2O2 was added daily over the course of the culture, the accumulation of trichothecenes was rapidly and strongly enhanced. The fungus may adapt to oxidative stress when the first exposure to H2O2 occurs at the beginning of the culture course. The highest toxin levels were measured when the H2O2 was added daily. The importance of the first hours of culture was confirmed: pre-treating conidia with H2O2 does not affect their germination kinetics but leads to a reduction in the yield of trichothecenes 40 days later. The H2O2 regulation of this trichothecene accumulation may be specific, as paraquat, another pro-oxidant compound, inhibits their production. Since H2O2 is a major component of the oxidative burst occurring in pathogen/host interactions, these data support the theory that trichothecenes may act as virulence factors. [source] Overproduction of reactive oxygen species in end-stage renal disease patients: A potential component of hemodialysis-associated inflammationHEMODIALYSIS INTERNATIONAL, Issue 1 2005Marion Morena Abstract During the past decade, hemodialysis (HD)-induced inflammation has been linked to the development of long-term morbidity in end-stage renal disease (ESRD) patients on regular renal replacement therapy. Because interleukins and anaphylatoxins produced during HD sessions are potent activators for nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, an example of an enzyme that is responsible for overproduction of reactive oxygen species (ROS), this may constitute a link between leukocyte activation and cell or organ toxicity. Oxidative stress, which results from an imbalance between oxidant production and antioxidant defense mechanisms, has been documented in ESRD patients using lipid and/or protein oxidative markers. Characterization of HD-induced oxidative stress has included identification of potential activators for NADPH oxidase. Uremia per se could prime phagocyte oxidative burst. HD, far from improving the oxidative status, results in an enhancement of ROS owing to hemoincompatibility of the dialysis system, hemoreactivity of the membrane, and trace amounts of endotoxins in the dialysate. In addition, the HD process is associated with an impairment in antioxidant mechanisms. The resulting oxidative stress has been implicated in long-term complications including anemia, amyloidosis, accelerated atherosclerosis, and malnutrition. Prevention of oxidative stress in HD might focus on improving the hemocompatibility of the dialysis system, supplementation of deficient patients with antioxidants, and modulation of NADPH oxidase by pharmacologic approaches. [source] Ammonia impairs neutrophil phagocytic function in liver disease,HEPATOLOGY, Issue 4 2008Debbie L. Shawcross Hyperammonemia is a feature of liver failure, which is associated with increased risk of infection. The aims of the present study were to determine in vitro, in rats fed an ammoniagenic diet and in patients with cirrhosis, whether induction of hyperammonemia results in neutrophil dysfunction. As hyperammonemia produces cell swelling, we explored the role of the osmoregulating, p38 mitogen-activated protein kinase (p38MAPK) pathway in mediating this neutrophil dysfunction. Neutrophils were isolated from blood of healthy volunteers and incubated with either 75 ,M ammonia or phosphate-buffered saline. Both groups were studied under hyponatremic conditions and/or with the addition of p38MAPK modulators. Neutrophil phagocytosis was measured in naive rats and rats fed an ammoniagenic diet and in patients with stable cirrhosis given placebo (n = 8) or an amino acid solution inducing hyperammonemia (n = 8). Cell volume and phagocytosis was analyzed by fluorescent-activated cell sorting using fluorescein isothiocyanate,labeled E. coli. p38MAPK phosphorylation was measured by western blotting. In healthy neutrophils incubated with ammonia and in rats fed an ammoniagenic diet, neutrophils showed evidence of swelling, impaired phagocytosis, and increased spontaneous oxidative burst compared to controls. Phagocytosis was significantly impaired in patients with induced hyperammonemia compared to placebo. The effects of hyperammonemia and hyponatremia were synergistic. The p38MAPK intracellular signaling pathways were activated in healthy neutrophils exposed to ammonia in association with increased burst activity. Neutrophil phagocytic dysfunction was abrogated by the addition of a p38MAPK agonist. Conclusion: Ammonia produces neutrophil swelling and impairs neutrophil phagocytosis. The p38MAPK intracellular signaling pathway has been shown to be important in mediating the ammonia-induced neutrophil dysfunction. (HEPATOLOGY 2008.) [source] Interferon-, activation of polymorphonuclear neutrophil functionIMMUNOLOGY, Issue 1 2004Terri N. Ellis Summary As current research illuminates the dynamic interplay between the innate and acquired immune responses, the interaction and communication between these two arms has yet to be fully investigated. Polymorphonuclear neutrophils (PMNs) and interferon-, (IFN-,) are known critical components of innate and acquired immunity, respectively. However, recent studies have demonstrated that these two components are not entirely isolated. Treatment of PMNs with IFN-, elicits a variety of responses depending on stimuli and environmental conditions. These responses include increased oxidative burst, differential gene expression, and induction of antigen presentation. Many of these functions have been overlooked in PMNs, which have long been classified as terminal phagocytic cells incapable of protein synthesis. As this review reports, the old definition of the PMN is in need of an update, as these cells have demonstrated their ability to mediate the transition between the innate and acquired immune responses. [source] Interaction between leucocytes and human spermatozoa influencing reactive oxygen intermediates releaseINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 2 2004Monika Fr Summary The relationship between the presence of white blood cells (WBCs) and the fertilizing potential of human semen is still an open question. It is well known that the presence of leucocytes in human semen can be related to the production of reactive oxygen intermediates (ROI). Semen samples were obtained from 15 normozoospermic men and leucocytes were isolated from heparinized blood drawn from 15 volunteers. Lucigenin and luminol-mediated chemiluminescence assays were used to determine reactive oxygen species (ROS) generation by non-activated or activated leucocytes through 12-myristate-13-acetate or N-formyl-methionyl-leucyl-phenyalanine (FMLP) before the addition of spermatozoa isolated by swim-up or Percoll procedures. All spermatozoal fractions used in this study were characterized by defining their motility, morphology and viability. The levels of ROS formation by non-activated as well as stimulated leucocytes were significantly decreased after addition of swim-up separated spermatozoa (p < 0.01). The ability to inhibit the basal chemiluminescence was of lower degree for spermatozoa isolated from 90% Percoll fractions than for swim-up sperm. However, addition of sperm cells from 47% Percoll fraction was found to increase both lucigenin and luminol signals. Moreover, the determined ROI levels changed depending on the type of inducing factor used for oxidative burst. Then, spermatozoa selected by swim-up procedure although with only slightly higher viability and morphology than sperm obtained from 90% Percoll fraction clearly exhibited much higher capacity to inhibit ROI secretion by receptor-stimulated leucocytes (FMLP-activation) than Percoll fractionated sperm. Such results may indicate that within normal semen may exist sperm subpopulations with different biochemical mechanisms controlling the interaction between spermatozoa and contaminating leucocytes. When ROI levels contained in normozoospermic semen are dependent on the WBCs activation, it seems that spermatozoa with preserved normal functional competence are able to defend themselves against leucocytes-derived ROI. Also for normozoospermic ejaculates, swim-up sperm may improve semen antioxidant characteristics when comparing with Percoll (90%) separated sperm. It may help for optimal sperm preparation when assisting to infertility treatment. [source] EVIDENCE OF A LATENT OXIDATIVE BURST IN RELATION TO WOUND REPAIR IN THE GIANT UNICELLULAR CHLOROPHYTE DASYCLADUS VERMICULARIS,JOURNAL OF PHYCOLOGY, Issue 3 2005Cliff Ross We investigated the kinetics and composition of the second phase of the wound repair process of Dasycladus vermicularis ([Scropoli] Krasser) using fluorescent probes, chromatography, UV spectroscopy, and histochemistry. Our new evidence supports the hypothesis that the second phase of wound repair (initiated at approximately 35,45 min postinjury) is based on the activation of an oxidative burst that produces micromolar H2O2 levels. These results provide evidence of peroxidase activity at the wound site, real-time measurements of an oxidative burst, and catechol localization in wound plugs. Strong evidence is presented indicating that the biochemical machinery exists for oxidative cross-linking to ensue in the wound-healing process of D. vermicularis. [source] Acute Alcohol Intoxication During Hemorrhagic Shock: Impact on Host Defense From InfectionALCOHOLISM, Issue 4 2004K. L. Zambell Abstract: Background: Acute alcohol intoxication is a frequent underlying condition associated with traumatic injury. Our studies have demonstrated that acute alcohol intoxication significantly impairs the immediate hemodynamic, metabolic, and inflammatory responses to hemorrhagic shock. This study investigated whether acute alcohol intoxication during hemorrhagic shock would alter the outcome from an infectious challenge during the initial 24 hr recovery period. Methods: Chronically catheterized male Sprague Dawley® rats were randomized to acute alcohol intoxication (EtOH; 1.75 g/kg bolus followed by a constant 15 hr infusion at 250,300 mg/kg/hr) or isocaloric isovolemic dextrose infusion (dex; 3 ml + 0.375 ml/hr). EtOH and dex were assigned to either fixed-volume (50%) hemorrhagic shock followed by fluid resuscitation with Ringer's lactate (EtOH/hem, dex/hem) or sham hemorrhagic shock (EtOH/sham, dex/sham). Indexes of circulating neutrophil function (apoptosis, phagocytosis, oxidative burst) were obtained at baseline, at completion of hemorrhagic shock, and at the end of fluid resuscitation. Bacterial clearance, lung cytokine expression, and myeloperoxidase activity were determined at 6 and 18 hr after an intratracheal challenge with Klebsiella pneumoniae (107 colony-forming units). Results: Mean arterial blood pressure was significantly lower in acute alcohol intoxication-hemorrhagic shock animals throughout the hemorrhagic shock. In sham animals, acute alcohol intoxication alone did not produce significant changes in neutrophil apoptosis or phagocytic activity but significantly suppressed phorbol myristic acid (PMA)-stimulated oxidative burst. Hemorrhagic shock produced a modest increase in neutrophil apoptosis and suppression of neutrophil phagocytic capacity but significantly suppressed PMA-stimulated oxidative burst. Acute alcohol intoxication exacerbated the hemorrhagic shock-induced neutrophil apoptosis and the hemorrhagic shock-induced suppression of phagocytosis without further affecting PMA-stimulated oxidative burst. Fluid resuscitation did not restore neutrophil phagocytosis or oxidative burst. Acute alcohol intoxication decreased (,40%) 3-day survival from K. pneumoniae in hemorrhagic shock animals, impaired bacterial clearance during the first 18 hr postinfection, and prolonged lung proinflammatory cytokine expression. Conclusions: These results demonstrate that the early alterations in metabolic and inflammatory responses to hemorrhagic shock produced by acute alcohol intoxication are associated with neutrophil dysfunction and impaired host response to a secondary infectious challenge leading to increased morbidity and mortality. [source] Oxidative Stress and Neutrophil Function in Cats with Chronic Renal FailureJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 3 2010R.F. Keegan Background: Oxidative stress is an important component in the progression of chronic renal failure (CRF) and neutrophil function may be impaired by oxidative stress. Hypothesis: Cats with CRF have increased oxidative stress and decreased neutrophil function compared with control cats. Animals: Twenty cats with previously diagnosed renal failure were compared with 10 age-matched control cats. Methods: A biochemical profile, CBC, urinalysis, antioxidant capacity, superoxide dismutase (SOD) enzyme activity, reduced to oxidized glutathione ratio (GSH : GSSG), and neutrophil phagocytosis and oxidative burst were measured. Statistical comparisons (2-tailed t -test) were reported as mean ± standard deviation. Results: The CRF cats had significantly higher serum blood urea nitrogen, creatinine, and phosphorus concentrations than control cats, and significantly lower PCV and urine specific gravity than control cats. The GSH : GSSG ratio was significantly higher in the CRF group (177.6 ± 197, 61.7 ± 33; P < .02) whereas the antioxidant capacity was significantly less in the CRF group (0.56 ± 0.21, 0.81 ± 0.13 Trolox units; P < .005). SOD activity was the same in control and CRF cats. Neutrophil oxidative burst after Escherichia coli phagocytosis, measured as an increase in mean fluorescence intensity, was significantly higher in CRF cats than controls (732 ± 253, 524 ± 54; P < .05). Conclusions: The higher GSH : GSSG ratio and lower antioxidant capacity in CRF cats is consistent with activation of antioxidant defense mechanisms. It remains to be determined if supplementation with antioxidants such as SOD beyond the level of control cats would be of benefit in cats with CRF. [source] Oligocarrageenans and tissue-dependant oxidative burst in Solieria chordalis (Rhodophyceae, Gigartinales)PHYCOLOGICAL RESEARCH, Issue 1 2008Erwan Ar Gall SUMMARY The release of hydrogen peroxide by thallus fragments of the rhodophycean Solieria chordalis (C. Agardh) J. Agardh has been documented both in the presence and in the absence of oligosaccharides. Within 1 h, ramuli were able to release large amounts of peroxide in the absence of any chemical stress. Among potential elicitors tested, only degree of polymerization 1 (DP1) and DP7-8 oligo-iota-carrageenans stimulated defense mechanisms in both axes and ramuli as shown by the occurrence of an oxidative burst. Chopping of the tissues had no effect on the intensity of the burst, therefore suggesting that mainly cortical cell layers were involved in the process. After 5 min incubation, a dose of 125 ,g mL,1 of an oligomeric mixture containing a large proportion of DP1 units proved to be sufficient to obtain a maximal response. The intensity of the burst was significantly higher with isolated ramuli than with pieces of the axis, with outer peroxide accumulations reaching 200 nmol g,1 fresh weight of treated tissue. Altogether, our results show that S. chordalis is able to react to a simulated pathogen attack by an oxidative burst and that the capacity to carry out an oxidative burst is stronger in ramuli than in axes. [source] In vivo monitor oxidative burst induced by Cd2+ stress for the oilseed rape (Brassica napus L.) based on electrochemical microbiosensorPHYTOCHEMICAL ANALYSIS, Issue 2 2010Qiao Xu Abstract Introduction , Since the mechanism of Cd2+ stress for plants is not clear, an in vivo method to monitor Cd2+ stress for plants is necessary. However, oxidative burst (OB) is a signal messenger in the process of Cd2+ stress for plants. Objective , To establish an electrochemical method with poly- o -phenylenediamine and Pt microparticle modified Pt electrode (POPD,Pt-MP,Pt) as a microbiosensor for the in vivo detection of oxidative burst induced by Cd2+ stress in oilseed rape (Brassica napus L.). Methodology , The optimal fabrication of POPD,Pt-MP,Pt biosensor was achieved. Electrochemical signal was collected by amperometry. Results , After oilseed rape was exposed to 84.9,mM CdCl2 stress, three oxidative bursts were observed in oilseed rape by amperometry at 3.3,h, 8.4,h and 13.2,h, respectively. However, there was no obvious signal observed in the controlled assay. Conclusion , This contribution presents the in vivo monitoring of the OB process induced by Cd2+ stress in oilseed rape by POPD,Pt-MP,Pt microbiosensor in real-time. The novel electrochemical microbiosensor not only facilitates the real-time study in plant self-defence response to the adverse environment such as Cd2+ stress, but also provides an effective tool for probing the self-defence mechanism in plants. Copyright © 2009 John Wiley & Sons, Ltd. [source] Betulinic acid protects against ischemia/reperfusion-induced renal damage and inhibits leukocyte apoptosisPHYTOTHERAPY RESEARCH, Issue 3 2010Emel Ek, lu-Demiralp Abstract The possible protective effect of betulinic acid on renal ischemia/reperfusion (I/R) injury was studied. Wistar Albino rats were unilaterally nephrectomized and subjected to 45 min of renal pedicle occlusion followed by 6 h of reperfusion. Betulinic acid (250 mg/kg, i.p.) or saline was administered at 30 min prior to ischemia and immediately before the reperfusion. Creatinine, blood urea nitrogen (BUN), lactate dehydrogenase (LDH) and TNF-, as well as the oxidative burst of neutrophil and leukocyte apoptosis were assayed in blood samples. Malondialdehyde (MDA), glutathione (GSH) levels, Na+, K+ -ATPase and myeloperoxidase (MPO) activities were determined in kidney tissue which was also analysed microscopically. I/R caused significant increases in blood creatinine, BUN, LDH and TNF-,. In the kidney samples of the I/R group, MDA levels and MPO activity were increased significantly, however, GSH levels and Na+, K+ -ATPase activity were decreased. Betulinic acid ameliorated the oxidative burst response to both formyl-methionyl-leucyl-phenylalanine (fMLP) and phorbol 12-myristate 13-acetate (PMA) stimuli, normalized the apoptotic response and most of the biochemical indices as well as histopathological alterations induced by I/R. In conclusion, these data suggest that betulinic acid attenuates I/R-induced oxidant responses, improved microscopic damage and renal function by regulating the apoptotic function of leukocytes and inhibiting neutrophil infiltration. Copyright © 2009 John Wiley & Sons, Ltd. [source] Isolation and immunomodulatory properties of a flavonoid, casticin from Vitex agnus-castusPHYTOTHERAPY RESEARCH, Issue 11 2009M. Ahmed Mesaik Abstract Casticin (1), a flavonoid isolated from the aerial parts of Vitex agnus-castus, was found to be a potent immunomodulatory and cytotoxic compound. The activity was tested in vitro for chemiluminescence, chemotaxis, T-cell proliferation and cytotoxicity. Casticin (1) exhibited a significant inhibitory effect on monocyte oxidative burst in a dose dependent manner. It was found to have a significant suppressive effect on the chemotaxic action at higher concentrations on fMLP (10,8m) stimulated neutrophils. It also showed a potent suppressive effect on PHA stimulated T-cell (PMBC). Copyright © 2009 John Wiley & Sons, Ltd. [source] The effect of drought and ultraviolet radiation on growth and stress markers in pea and wheatPLANT CELL & ENVIRONMENT, Issue 12 2001V. Alexieva Abstract It emerged recently that there is an inter-relationship between drought and ultraviolet-B (UV-B) radiation in plant responses, in that both stresses provoke an oxidative burst. The purpose of this investigation was to compare the effects and interaction of drought and UV-B in wheat and pea. The absence of changes in relative leaf water content (RWC) after UV-B treatments indicate that changes in water content were not involved. RWC was the main factor resulting in reduced growth in response to drought. Increases in anthocyanin and phenols were detected after exposure to UV-B. The increases do not appear to be of sufficient magnitude to act as a UV-B screen. UV-B application caused greater membrane damage than drought stress, as assessed by lipid peroxidation as well as osmolyte leakage. An increase in the specific activities of antioxidant enzymes was measured after UV-B alone as well as after application to droughted plants. Proline increased primarily in drought-stressed pea or wheat. Proline may be the drought-induced factor which has a protective role in response to UV-B. The physiological and biochemical parameters measured indicate the UV-B light has stronger stress effectors than drought on the growth of seedlings of both species. The two environmental stresses acted synergistically to induce protective mechanisms in that pre-application of either stress reduced the damage caused by subsequent application of the other stress. [source] Molecular analysis of resistance mechanisms to Orobanche cumana in sunflowerPLANT PATHOLOGY, Issue 3 2007P. Letousey Resistance to the dicotyledenous parasite Orobanche cumana in sunflower is characterized by a low number of parasitic attachments and a confinement of the parasite in host tissues leading to its necrosis. To help understand what determines such resistance mechanisms, molecular, biochemical and histological approaches were employed before (early response) and after (late response) attachment of the broomrape parasite to susceptible (2603) and resistant (LR1) sunflower genotypes. The expression patterns of 11 defence-related genes known to be involved in different metabolic pathways (phenylpropanoids, jasmonate, ethylene) and/or in resistance mechanisms against microorganisms were investigated. RT-PCR and cDNA blot experiments revealed that the resistant genotype exhibited a stronger overall defence response against O. cumana than the susceptible one, involving marker genes of the jasmonate (JA) and salicylic acid (SA) pathways. Among them, the SA-responsive gene, def. (defensin), appeared to be characteristic of LR1 sunflower resistance. However, no JA accumulation and similar SA contents (250,300 ng g,1 FW) were measured by GC/MS in both genotypes, parasitized or not. In addition, three cDNAs, isolated by a suppression-subtractive hybridization, were shown to be strongly induced only in the resistant genotype 8 days post-inoculation, when the first O. cumana attachments occurred. These genes, putatively encoding a methionine synthase, a glutathione S-transferase and a quinone oxidoreductase, might be involved in detoxification of reactive oxygen species, suggesting the occurrence of an oxidative burst during the incompatible interaction. Finally, host cell-wall modifications leading to parasite-confinement were correlated with more intense callose depositions in the resistant genotype, concomitant with over-expression of the callose synthase cDNA HaGSL1. [source] The chloroplast protein RPH1 plays a role in the immune response of Arabidopsis to Phytophthora brassicaeTHE PLANT JOURNAL, Issue 2 2009Khaoula Belhaj Summary Plant immune responses to pathogens are often associated with enhanced production of reactive oxygen species (ROS), known as the oxidative burst, and with rapid hypersensitive host cell death (the hypersensitive response, HR) at sites of attempted infection. It is generally accepted that the oxidative burst acts as a promotive signal for HR, and that HR is highly correlated with efficient disease resistance. We have identified the Arabidopsis mutant rph1 (resistance to Phytophthora 1), which is susceptible to the oomycete pathogen Phytophthora brassicae despite rapid induction of HR. The susceptibility of rph1 was specific for P. brassicae and coincided with a reduced oxidative burst, a runaway cell-death response, and failure to properly activate the expression of defence-related genes. From these results, we conclude that, in the immune response to P. brassicae, (i) HR is not sufficient to stop the pathogen, (ii) HR initiation can occur in the absence of a major oxidative burst, (iii) the oxidative burst plays a role in limiting the spread of cell death, and (iv) RPH1 is a positive regulator of the P. brassicae -induced oxidative burst and enhanced expression of defence-related genes. Surprisingly, RPH1 encodes an evolutionary highly conserved chloroplast protein, indicating a function of this organelle in activation of a subset of immune reactions in response to P. brassicae. The disease resistance-related role of RPH1 was not limited to the Arabidopsis model system. Silencing of the potato homolog StRPH1 in a resistant potato cultivar caused susceptibility to the late blight pathogen Phytophthora infestans. [source] Identification of a putative voltage-gated Ca2+ channel as a key regulator of elicitor-induced hypersensitive cell death and mitogen-activated protein kinase activation in riceTHE PLANT JOURNAL, Issue 6 2005Takamitsu Kurusu Summary Elicitor-triggered transient membrane potential changes and Ca2+ influx through the plasma membrane are thought to be important during defense signaling in plants. However, the molecular bases for the Ca2+ influx and its regulation remain largely unknown. Here we tested effects of overexpression as well as retrotransposon (Tos17)-insertional mutagenesis of the rice two-pore channel 1 (OsTPC1), a putative voltage-gated Ca2+ -permeable channel, on a proteinaceous fungal elicitor-induced defense responses in rice cells. The overexpressor showed enhanced sensitivity to the elicitor to induce oxidative burst, activation of a mitogen-activated protein kinase (MAPK), OsMPK2, as well as hypersensitive cell death. On the contrary, a series of defense responses including the cell death and activation of the MAPK were severely suppressed in the insertional mutant, which was complemented by overexpression of the wild-type gene. These results suggest that the putative Ca2+ -permeable channel determines sensitivity to the elicitor and plays a role as a key regulator of elicitor-induced defense responses, activation of MAPK cascade and hypersensitive cell death. [source] Bactericidal activity of neutrophils with reduced oxidative burst from adults with bronchiectasisAPMIS, Issue 2 2009PAUL KING Recent work has shown that the most common abnormality on screening of immune function in cohort of adult subjects with bronchiectasis was a low neutrophil oxidative burst. To assess the functional significance of a low oxidative burst in subjects with idiopathic bronchiectasis. Neutrophils with a low oxidative burst were obtained from six bronchiectasis patients and assessed for their ability to kill Staphylococcus aureus. The results were compared with those obtained using neutrophils from 12 healthy controls subjects and control neutrophils treated with dimethylthiourea (DMTU), an inhibitor of the oxidative burst. The results showed that the bronchiectasis subjects had significantly reduced killing of bacteria compared with controls (p<0.001). The addition of DMTU to neutrophils of control subjects significantly impaired both the oxidative burst and bactericidal activity. The addition of interferon-, enhanced oxidative burst in both groups. Abnormal neutrophil function in some subjects with bronchiectasis may account for their high rate of infection. [source] Breaking T cell tolerance against self type II collagen in HLA,DR4,transgenic mice and development of autoimmune arthritisARTHRITIS & RHEUMATISM, Issue 7 2010Tsvetelina Batsalova Objective To establish a new animal model in DRB1*0401 (DR4),transgenic mice in which T cell tolerance to self type II collagen (CII) can be broken and allow for the development of autoimmune arthritis, to investigate the role of posttranslational modifications of the CII259,273 epitope in the induction and breaking of tolerance of DR4-restricted T cells, and to characterize DR4-restricted T cell recognition of the immunodominant CII259,273 epitope. Methods DR4-transgenic mice expressing either the entire human CII protein (HuCII) or only the immunodominant T cell epitope of heterologous CII (MMC) in joint cartilage were established on different genetic backgrounds, and susceptibility to collagen-induced arthritis (CIA) was tested. Results HuCII mice displayed stronger T cell tolerance to heterologous CII than did MMC mice. On the B10 background, arthritis developed only in MMC mice with a defective oxidative burst. However, MMC mice on the C3H background were susceptible to arthritis also with a functional oxidative burst. Significant recall responses in tolerized mice were detected only against the nonglycosylated CII259,273 epitope. Recognition of the CII259,273 epitope was heterogeneous, but the majority of T cells in DR4 mice specifically recognized the nonglycosylated side chain of lysine at position 264. Conclusion It is possible to break tolerance to self CII and induce arthritis in DR4 mice. However, arthritis susceptibility is tightly controlled by the genetic background and by the source of the transgenic element for expressing the heterologous CII peptide as a self CII protein in the joint. In contrast to CIA in Aq -expressing mice, the nonglycosylated CII259,273 epitope is clearly immunodominant in both tolerized and nontolerized DR4 mice. [source] Abrogation of antibody-induced arthritis in mice by a self-activating viridin prodrug and association with impaired neutrophil and endothelial cell functionARTHRITIS & RHEUMATISM, Issue 8 2009Lars Stangenberg Objective To test a novel self-activating viridin (SAV) prodrug that slowly releases wortmannin, a potent phosphoinositide 3-kinase inhibitor, in a model of antibody-mediated inflammatory arthritis. Methods The SAV prodrug was administered to K/BxN mice or to C57BL/6 (B6) mice that had been injected with K/BxN serum. Ankle thickness was measured, and histologic changes were scored after a 10-day disease course (serum-transfer arthritis). Protease activity was measured by a near-infrared imaging approach using a cleavable cathepsin,selective probe. Further near-infrared imaging techniques were used to analyze early changes in vascular permeability after serum injection, as well as neutrophil,endothelial cell interactions. Neutrophil functions were assessed using an oxidative burst assay as well as a degranulation assay. Results SAV prevented ankle swelling in mice with serum-transfer arthritis in a dose-dependent manner. It also markedly reduced the extent of other features of arthritis, such as protease activity and histology scores for inflammation and joint erosion. Moreover, SAV was an effective therapeutic agent. The underlying mechanisms for the antiinflammatory activity were manifold. Endothelial permeability after serum injection was reduced, as was firm neutrophil attachment to endothelial cells. Endothelial cell activation by tumor necrosis factor , was impeded by SAV, as measured by the expression of vascular cell adhesion molecule. Crucial neutrophil functions, such as generation of reactive oxygen species and degranulation of protease-laden vesicles, were decreased by SAV administration. Conclusion A novel SAV prodrug proved strongly antiinflammatory in a murine model of antibody-induced inflammatory arthritis. Its activity could be attributed, at least in part, to the inhibition of neutrophil and endothelial cell functions. [source] Coexpression of CD177 and membrane proteinase 3 on neutrophils in antineutrophil cytoplasmic autoantibody,associated systemic vasculitis: Anti,proteinase 3,mediated neutrophil activation is independent of the role of CD177-expressing neutrophilsARTHRITIS & RHEUMATISM, Issue 5 2009N. Hu Objective Wegener's granulomatosis (WG) is strongly associated with antineutrophil cytoplasmic autoantibodies (ANCAs) directed against proteinase 3 (PR3). Recent studies have shown that membrane-bound PR3 (mPR3) is differentially expressed and colocalizes with CD177/NB1 on circulating neutrophils. We undertook this study to assess the differential expression of CD177 on neutrophils from patients with ANCA-associated systemic vasculitis (ASV) in comparison with patients with systemic lupus erythematosus (SLE), patients with rheumatoid arthritis (RA), and healthy individuals, and to investigate whether colocalization of mPR3 and CD177 affects anti-PR3,mediated neutrophil activation. Methods Expression of CD177 and mPR3 was analyzed by flow cytometry on isolated neutrophils from patients with ASV (n = 53), those with SLE (n = 30), those with RA (n = 26), and healthy controls (n = 31). Neutrophil activation mediated by anti-PR3 antibodies was assessed by measuring the oxidative burst with a dihydrorhodamine assay. Results Percentages of CD177-expressing neutrophils were significantly higher in patients with ASV and those with SLE than in healthy controls. In 3 healthy donors, CD177 expression was not detected. After priming with tumor necrosis factor ,, neutrophils remained negative for CD177 while mPR3 expression was induced. Neutrophils from CD177-negative donors or CD177, neutrophils sorted from donors with bimodal expression were susceptible to anti-PR3,mediated oxidative burst. Variation in the extent of anti-PR3,mediated neutrophil activation among different donors occurred independent of the percentage of CD177-expressing neutrophils. Conclusion Membrane expression of CD177 on circulating neutrophils is increased in patients with ASV and in those with SLE, but not in RA patients. However, primed neutrophils from CD177-negative individuals also express mPR3 and are susceptible to anti-PR3,mediated oxidative burst, suggesting that recruitment of CD177-independent mPR3 is involved in anti-PR3,induced neutrophil activation. [source] Oxidative Burst in Suspension Culture of Taxus cuspidataInduced by a Laminar Shear Stress in Short-TermBIOTECHNOLOGY PROGRESS, Issue 2 2004Rong-Bin Han Generation of active oxidative species induced by shear stress in suspension cultures of Taxus cuspidata was investigated in a Couette-type shear reactor. It was found that T. cuspidata cells respond to a shear rate of 95 s,1 with oxidative bursts. Their triphasic characteristics in 6 h were similar in both intracellular H2O2 production and extracellular O2,, production. Additionally, inhibition studies with diphenylene iodonium and azide suggested that the key enzyme responsible for oxidative bursts under the shear rate of 95 s,1 is primarily NADPH oxidase and the contribution of peroxidase for oxidative bursts was less. Investigation of the relationship between active oxidative species and defense responses induced by the shear stress indicated that the O2,, burst may account for the change of membrane permeability, and the H2O2 burst plays an important role in inducing secondary metabolites such as the activation of phenylalanine ammonia lyase enzyme and phenolic accumulation. Furthermore, oxidative bursts elicited by the shear rate of 95 s,1 were suppressed by treatment with suramin, nifedipine, and neomycin prior to the shear stress treatment, suggesting that G-protein, Ca2+ channel, and phospholipase C are involved in the signal pathway for oxidative bursts induced by the shear stress. A model is proposed to explain the oxidative burst in cultured T. cuspidata cells challenged with the shear stress. [source] Functional basis for complement evasion by staphylococcal superantigen-like 7CELLULAR MICROBIOLOGY, Issue 10 2010Jovanka Bestebroer Summary The human pathogen Staphylococcus aureus has a plethora of virulence factors that promote its colonization and survival in the host. Among such immune modulators are staphylococcal superantigen-like (SSL) proteins, comprising a family of 14 small, secreted molecules that seem to interfere with the host innate immune system. SSL7 has been described to bind immunoglobulin A (IgA) and complement C5, thereby inhibiting IgA-Fc,RI binding and serum killing of Escherichia coli. As C5a generation, in contrast to C5b-9-mediated lysis, is crucial for immune defence against staphylococci, we investigated the impact of SSL7 on staphylococcal-induced C5a-mediated effects. Here, we show that SSL7 inhibits C5a generation induced by staphylococcal opsonization, slightly enhanced by its IgA-binding capacity. Moreover, we demonstrate a strong protective activity of SSL7 against staphylococcal clearance in human whole blood. SSL7 strongly inhibited the C5a-induced phagocytosis of S. aureus and oxidative burst in an in vitro whole-blood inflammation model. Furthermore, we found that SSL7 affects all three pathways of complement activation and inhibits the cleavage of C5 by interference of its binding to C5 convertases. Finally, SSL7 effects were also demonstrated in vivo. In a murine model of immune complex peritonitis, SSL7 abrogated the C5a-driven influx of neutrophils in mouse peritoneum. [source] Assessing immune function in adult bronchiectasisCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 3 2006P. T. King Summary Bronchiectasis is characterized by chronic airway infection and damage and remains an important health problem. Recent literature has emphasized the role of host defence and immune deficiency in the pathogenesis of bronchiectasis, but there have been few studies of immune function in adult bronchiectasis. A comprehensive screen of immune function was conducted in 103 adult patients with bronchiectasis, encompassing full blood examinations, immunoglobulins and IgG isotypes, complement levels, lymphocyte subsets and neutrophil function. Full blood examinations were normal in this cohort, as were complement levels. Statistical analysis confirmed that a significant number of subjects had low levels of IgG3 (13 patients), B cell lymphocytes (six patients) and T helper cell lymphocytes (seven patients) when compared with controls (P < 0·05). The most common abnormality was found with testing of the neutrophil oxidative burst. All subjects had a normal neutrophil phagocytic function but 33 of the subjects had an oxidative burst that was below the normal range (P < 0001). Almost half the group (45 subjects) had abnormally low levels of one of these four parameters. The findings of low B cells, Th cells and oxidative burst in bronchiectasis are novel. The results emphasize the importance of immune function assessment for adult bronchiectasis. [source] | ||||||||||||||||