The pathogenesis of sepsis and its progression to multiple organ dysfunction syndrome and septic shock have been the subject of investigations for nearly half a century. Controversies still exist with regard to understanding the molecular pathophysiology of sepsis in relation to the complex roles played by reactive oxygen species, nitric oxide, complements and cytokines. In the present review we categorise the key turning points in sepsis development and outline the most probable sequence of events leading to cellular dysfunction and organ failure under septic conditions. We have applied an integrative approach in order to fuse current state-of-the-art knowledge about redox processes involving hydrogen peroxide, nitric oxide, superoxide, peroxynitrite and hydroxyl radical, which lead to mitochondrial respiratory dysfunction. Finally, from this point of view, the potential of redox therapy targeting sepsis is discussed.
A breakdown in homeostasis of redox-active metals represents an important factor for neurodegeneration. We have used EPR spectroscopy and BMPO spin-trap to investigate the catalytic properties and ligand modulation of redox activity of copper and iron in human cerebrospinal fluid (CSF). In contrast to iron, copper supplementation provoked a statistically significant increase in hydroxyl free radical generation in CSF treated with H(2)O(2). However, in a binary copper/iron containing Fenton system, iron catalytically activated copper. The chelator EDTA, which represents a model of physiological metal ligands, completely prevented copper's redox activity in CSF, while iron chelation led to a significant increase in hydroxyl radical generation, indicating that copper and iron do not only have diverse catalytic properties in the CSF but also that their redox activities are differently modulated by ligands. The application of DDC reduced hydroxyl radical generation in the CSF containing catalytically active metals (free Cu(2+) or Fe(3+)-EDTA complex). We conclude that chelators, such as DDC, are capable of preventing the prooxidative activity of both metals and may be suitable for reducing hydroxyl radical formation in certain pathophysiological settings.
River sediments are a major source of metal contamination in aquatic food webs. Due to the ability of metals to move up the food chain, fishes, occupying higher trophic levels, are considered to be good environmental indicators of metal pollution. The aim of this study was to analyze the metal content in tissues of the common barbel (Barbus barbus), a rheophilous cyprinid fish widely distributed in the Danube Basin, in order to find out if it can be used as a bioindicator of the metal content in the river sediment. We analyzed bioavailable concentrations of 15 elements (Al, As, B, Ba, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Se, Sr, and Zn) in sediments of the Danube (D), the Zapadna Morava (ZM), and the Južna Morava (JM) using the inductively coupled plasma spectroscopy (ICP-OES). The barbel specimens were collected in the proximity of sediment sampling sites for the analysis of metals in four tissues, gills, muscle, intestine, and liver. The sediment analysis indicated that the ZM is the most polluted with Cu, Ni, and Zn compared to other two rivers. The JM had the lowest concentrations of almost all observed elements, while the Danube sediments were mainly characterized by higher concentrations of Pb. The fish from the ZM had the highest concentration of Cu and Ni in the liver and intestine, and of Zn in the muscle tissue, which was in accordance with the concentrations of these metals in the sediment. Scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDS) was used for further analyses of metal interactions with fish tissues. The results suggest that the barbel can potentially be used as a bioindicator of sediment quality with respect to metal contamination.
Purpose The main objective of this study was to evaluate the concentrations and seasonal variations of trace elements in surface sediments of three major rivers in Serbia-the Danube, the Zapadna Morava (ZM), and the Južna Morava (JM)-according to sediment quality guidelines. The ZM and the JM create the Velika Morava River, one of the most important tributaries of the Danube, which has been characterized as a source of heavy metal pollution. Materials and methods The total concentrations of 15 elements (Al, As, B, Ba, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sr, and Zn) were determined in surface sediments (0-15 cm depth) collected during three seasons using inductively coupled plasma spectroscopy (ICP-OES). Principle component analysis (PCA) was used to identify the main variations in metal concentrations and grain size distribution. Scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDS) was used for grain analysis. Results and discussion PCA and three-way MANOVA results showed significant differences in element concentrations and grain size distribution between the rivers, and significant seasonal differences for each river. The concentrations of Cu and Ni exceeded sediment quality guideline levels in the ZM and the Danube, respectively, while excess Hg was detected in all three rivers. Concentrations of Al, Ba, Cu, Fe, Sr, and Zn significantly varied between seasons in the Danube and the ZM, being the highest in the summer. In the JM, concentrations of Al, As, Fe, Mn, and Zn varied with season, with the lowest values in the summer. The ZM had the highest percentage of silt and clay, and SEM-EDS analysis of ZM sediments showed associations of Cu with carbonate hydroxides and/or iron oxides in particles <100 μm. The results suggested that mining and industrial activities could be the sources of increased levels of metals in the ZM. Conclusions The sediments collected from the ZM were considerably more polluted with heavy metals in comparison to the JM. Cu was identified as a heavy metal of greatest risk in the ZM. The ZM was indicated as the main source of heavy metal delivery in the Velika Morava and Danube rivers. It is suggested that the main factors influencing pollution levels could be anthropogenic sources and industrial and mining activities, while seasonal changes might be related to dynamics of water flow and morphological characteristics of the two tributary rivers. Abbreviations ICP-OESInductively coupled plasma optical emission spectroscopy SEM-EDS Scanning electron microscopy/energy dispersive X-ray spectroscopy Responsible editor: Marcel van der Perk Electronic supplementary material The online version of this article (
Metabolism of metals in microalgae and the adaptation to metal excess are of significant environmental importance. We report here a three-step mechanism that the green microalga Chlorella sorokiniana activates during the acquisition of and adaptation to manganese (Mn), which is both, an essential trace metal and a pollutant of waters. In the early stage, Mn 2+ was mainly bound to membrane phospholipids and phosphates in released mucilage. The outer cell wall was reorganized, and lipids were accumulated with a relative increase in lipid saturation. Intracellular redox settings were rapidly altered in the presence of Mn excess, with increased production of reactive oxygen species that resulted in lipid peroxidation and a decrease in the level of thiols. In the later stage, Mn 2+ was chelated by polyphosphates and accumulated in the cells. The structure of the inner cell wall was modified and the redox milieu established a new balance. Polyphosphates serve as a transient Mn 2+ storage ligand, as proposed previously. At the final stage, Mn was stored in multi-valent Mn clusters that resemble the structure of tetramanganese-calcium core of the oxygen-evolving complex. The present findings elucidate bioinorganic chemistry and metabolism of Mn in microalgae, and may shed new light on water-splitting Mn clusters.
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