Search results for "OXIDATION"
showing 10 items of 1913 documents
The role ofSphagnummosses in the methane cycling of a boreal mire
2010
Peatlands are a major natural source of atmospheric methane (CH4). Emissions from Sphagnum-dominated mires are lower than those measured from other mire types. This observation may partly be due to methanotrophic (i.e., methane-consuming) bacteria associated with Sphagnum. Twenty-three of the 41 Sphagnum species in Finland can be found in the peatland at Lakkasuo. To better understand the Sphagnum-methanotroph system, we tested the following hypotheses: (1) all these Sphagnum species support methanotrophic bacteria; (2) water level is the key environmental determinant for differences in methanotrophy across habitats; (3) under dry conditions, Sphagnum species will not host methanotrophic ba…
Abundant and diverse arsenic‐metabolizing microorganisms in peatlands treating arsenic‐contaminated mining wastewaters
2020
Mining operations produce large quantities of wastewater. At a mine site in Northern Finland, two natural peatlands are used for the treatment of mining‐influenced waters with high concentrations of sulfate and potentially toxic arsenic (As). In the present study, As removal and the involved microbial processes in those treatment peatlands (TPs) were assessed. Arsenic‐metabolizing microorganisms were abundant in peat soil from both TPs (up to 108 cells gdw‐1), with arsenate respirers being about 100 times more abundant than arsenite oxidizers. In uninhibited microcosm incubations, supplemented arsenite was oxidized under oxic conditions and supplemented arsenate was reduced under anoxic con…
Monitoring of headspace volatiles in milk‐cereal‐based liquid infant foods during storage
2006
The effect of storage (time and temperature) on the evolution of pentanal, hexanal, heptanal and pentane as volatile lipid oxidation products in two liquid ready-to-eat milk-cereal-based infant foods was studied. An SPME-GC method was used to this effect. Samples were stored for 9 months at 25, 30 and 37 °C and tested eight times during this period. Freshly produced infant foods contained pentanal, hexanal and heptanal (mean values: 10.71, 71.5 and 1.2 μg/kg, respectively), which decreased during the first 3 months of storage, although from the fourth month onwards no significant differences among storage times were found. Aldehyde content was inversely proportional to storage temperature. …
Inflammation in the Human Periodontium Induces Downregulation of the α1- and β1-Subunits of the sGC in Cementoclasts
2021
Nitric oxide (NO) binds to soluble guanylyl cyclase (sGC), activates it in a reduced oxidized heme iron state, and generates cyclic Guanosine Monophosphate (cGMP), which results in vasodilatation and inhibition of osteoclast activity. In inflammation, sGC is oxidized and becomes insensitive to NO. NO- and heme-independent activation of sGC requires protein expression of the &alpha
Structure, mechanism and regulation of peroxiredoxins.
2003
Peroxiredoxins (Prxs) are a ubiquitous family of antioxidant enzymes that also control cytokine-induced peroxide levels which mediate signal transduction in mammalian cells. Prxs can be regulated by changes to phosphorylation, redox and possibly oligomerization states. Prxs are divided into three classes: typical 2-Cys Prxs; atypical 2-Cys Prxs; and 1-Cys Prxs. All Prxs share the same basic catalytic mechanism, in which an active-site cysteine (the peroxidatic cysteine) is oxidized to a sulfenic acid by the peroxide substrate. The recycling of the sulfenic acid back to a thiol is what distinguishes the three enzyme classes. Using crystal structures, a detailed catalytic cycle has been deriv…
Argan oil prevents down-regulation induced by endotoxin on liver fatty acid oxidation and gluconeogenesis and on peroxisome proliferator-activated re…
2015
In patients with sepsis, liver metabolism and its capacity to provide other organs with energetic substrates are impaired. This and many other pathophysiological changes seen in human patients are reproduced in mice injected with purified endotoxin (lipopolysaccharide, LPS). In the present study, down-regulation of genes involved in hepatic fatty acid oxidation (FAOx) and gluconeogenesis in mice exposed to LPS was challenged by nutritional intervention with Argan oil. Mice given a standard chow supplemented or not with either 6% (w/w) Argan oil (AO) or 6% (w/w) olive oil (OO) prior to exposure to LPS were explored for liver gene expressions assessed by mRNA transcript levels and/or enzyme a…
Nitroblue-tetrazolium test for the functional evaluation of phagocytic cells: a critical analysis of the methodology.
1981
The reduction of NBT to formazan has been suggested as an indicator of the reduction potential of biological systems. An increase in the amount of reduced formazan reflects the activation of the hexose monophosphate shunt of phagocytes cultivated in vitro, as a result of cellular stimulation by chemical or biological factors, or during phagocytosis. This phenomenon has been widely used for the determination of activated phagocytes by different methods. However, the technical limitations of these methods have not been evaluated carefully. In the investigations presented here three solvents for formazan, pyridine, dioxane and dimethyl-formamide, have been tested for their suitability as extra…
Functional Magnetic Mesoporous Silica Microparticles Capped with an Azo-Derivative: A Promising Colon Drug Delivery Device
2018
[EN] Magnetic micro-sized mesoporous silica particles were used for the preparation of a gated material able to release an entrapped cargo in the presence of an azo-reducing agent and, to some extent, at acidic pH. The magnetic mesoporous microparticles were loaded with safranin O and the external surface was functionalized with an azo derivative 1 (bearing a carbamate linkage) yielding solid S1. Aqueous suspensions of S1 at pH 7.4 showed negligible safranin O release due to the presence of the bulky azo derivative attached onto the external surface of the inorganic scaffold. However, in the presence of sodium dithionite (azoreductive agent), a remarkable safranin O delivery was observed. A…
Semisynthesis of the Antiviral Abietane Diterpenoid Jiadifenoic Acid C from Callitrisic Acid (4-Epidehydroabietic Acid) Isolated from Sandarac Resin
2014
The semisynthesis of the antiviral abietane diterpenoid (+)-jiadifenoic acid C starting from the available methyl ester of callitrisic acid (4-epidehydroabietic acid) isolated from sandarac resin is reported. A protocol for the isolation of methyl callitrisate (methyl 4-epidehydroabietate) in gram quantities from sandarac resin is also described. Allylic C-17 oxygenation was introduced by regioselective dehydrogenation of the isopropyl group of methyl callitrisate with DDQ followed by selenium-catalyzed allylic oxidation. Ester hydrolysis afforded (+)-jiadifenoic acid C in 22% overall yield from methyl callitrisate. This semisynthetic route provides a convenient source of this anti-Coxsacki…
Inhibitory Effects of Various Extracts of Argentine Plant Species on Free-radical-mediated Reactions and Human Neutrophil Functions
1996
Extracts of Argentine plant species used in folk medicine were evaluated for their antioxidant properties and ability to influence human neutrophil functions, including superoxide anion release and degranulation. The infusion and methanol extract of Achyrocline flaccida, and the infusion of Pterocaulon polystachium exhibited chain-breaking antioxidant activity in Fe 2+ /ascorbate-induced lipid peroxidation of rat liver microsomal fractions and scavenged peroxyl radicals in an aqueous assay system. Nevertheless their superoxide scavenging ability was lower. The dichloromethane extracts of Phyllanthus sellowianus, Achyrocline flaccida, Gamochaeta simplicicaulis, Pterocaulon polystachium and E…