Content Of Oxidation Products Research Articles

Electrochemical conversion of lignin to useful chemicals

Electrochemical conversion of waste lignin from pulping mills and biorefineries is an alternative renewable process for generating industrial chemicals that may afford better control over conversion than other catalytic or thermochemical processes because the electrode potential, and hence the reaction energetics, can be controlled. The authors report here electrochemical oxidation of lignin on a Co core/Pt partial shell nanoparticle alloy electrocatalyst, identify several oxidation products, and quantify oxidation product concentration as a function of oxidation time. Key results show that useful chemicals like heptane and apocynin are generated during the electrochemical oxidation of lignin. Some key oxidation product concentrations increase steadily over time, suggesting they are likely stable products that do not participate in other reactions. Concentrations of other oxidation products increase and then decrease with time, suggesting that they may participate in proceeding chemical or electrochemical reactions. Formation of other oxidation products like 1,3-bis(1,1-dimethylethyl)-benzene and 1,4-di-tert-butylphenol suggest oxidative decomposition initiated by hydroxyl radicals that are likely generated at the anode. Overall, the results suggest that electrochemical oxidation of lignin is complex, with possibly many competing homogeneous chemical and heterogeneous electrochemical reactions.

Production, composition, and oxidative stability of milk highly enriched in polyunsaturated fatty acids from dairy cows fed alfalfa protein concentrate or supplemental vitamin E

Given its elevated content of carotenoids, alfalfa protein concentrates (APC) have the potential to prevent oxidation of milk enriched in polyunsaturated fatty acids. The effects of feeding APC or supplemental vitamin E on production, composition, and oxidative stability of milk enriched in polyunsaturated fatty acids were evaluated using 6 lactating Holstein cows (224±18d in milk) in a replicated 3×3 Latin square (21-d periods, 14d for adaptation). Treatment diets contained (dry matter basis) (1) 9% soybean meal (control, CTL); (2) 9% soybean meal + 300 IU of vitamin E/kg (VitE treatment); or (3) 9% APC (APC treatment). Cows received a continuous abomasal infusion of 450g/d of linseed oil. As a result, milk fat content of cis-9,cis-12 18:2 increased from 1.08±0.13 to 3.9±0.40% (mean ± SD), whereas cis-9,cis-12,cis-15 18:3 increased from 0.40±0.04 to 14.27±1.81% during the experimental period compared with the pretrial period. Milk yield tended to be higher for APC (14.7kg/d) compared with CTL (13.4kg/d), and was greater than that for VitE (13.0kg/d). Protein yield was higher in cows fed APC (518g/d) compared with VitE (445g/d) but was not different from that in cows fed CTL (483g/d). These effects resulted in improved milk N efficiency in cows fed APC (26.1% of N intake secreted in milk) compared with CTL (23.0%) and VitE (22.9%). Feeding APC increased milk fat content of lutein (252μg/g) compared with CTL (204μg/g) and VitE (190μg/g). Milk fat content of vitamin E was higher for APC (34.5μg/g) compared with CTL (19.0μg/g) and tended to be lower than that with VitE (44.9μg/g). Redox potential of fresh milk from cows fed APC (152mV) was similar to that of VitE (144mV), but lower than that of CTL (189mV). Treatments had no effect on fresh milk contents of dissolved oxygen (8.1±1.5mg/L), and conjugated diene hydroperoxides (2.7±0.5mmol/L). The concentrations of volatile lipid oxidation products (propanal, hexanal, hept-cis-4-enal, 1-octen-3-one) tended to be decreased by APC relative to CTL, whereas similar values were observed for VitE, except for hexanal, which was reduced by 40% in VitE. In conclusion, feeding APC to lactating dairy cows could serve as a source of dietary protein that improves dietary N utilization efficiency, and also as a preharvest technology to increase natural antioxidant levels in milk to limit oxidation.

Up-Regulation of Mitochondrial Antioxidant Superoxide Dismutase Underpins Persistent Cardiac Nutritional-Preconditioning by Long Chain n-3 Polyunsaturated Fatty Acids in the Rat.

Reactive oxygen species paradoxically underpin both ischaemia/reperfusion (I/R) damage and ischaemic preconditioning (IPC) cardioprotection. Long-chain omega-3 polyunsaturated fatty acids (LCn-3 PUFA) are highly susceptible to peroxidation, but are paradoxically cardioprotective. This study tested the hypothesis that LCn-3 PUFA cardioprotection is underpinned by peroxidation, upregulating antioxidant activity to reduce I/R-induced lipid oxidation, and the mechanisms of this nutritional preconditioning contrast to mechanisms of IPC. Rats were fed: fish oil (LCn-3 PUFA); sunflower seed oil (n-6 PUFA); or beef tallow (saturated fat, SF) enriched diets for six weeks. Isolated hearts were subject to: 180 min normoxic perfusion; a 30 min coronary occlusion ischaemia protocol then 120 min normoxic reperfusion; or a 3 × 5 min global IPC protocol, 30 min ischaemia, then reperfusion. Dietary LCn-3 PUFA raised basal: membrane docosahexaenoic acid (22:6n-3 DHA); fatty acid peroxidisability index; concentrations of lipid oxidation products; and superoxide dismutase (MnSOD) activity (but not CuZnSOD or glutathione peroxidase). Infarct size correlated inversely with basal MnSOD activity (r2 = 0.85) in the ischaemia protocol and positively with I/R-induced lipid oxidation (lipid hydroperoxides (LPO), r2 = 0.475; malondialdehyde (MDA), r2 = 0.583) across ischaemia and IPC protocols. While both dietary fish oil and IPC infarct-reduction were associated with reduced I/R-induced lipid oxidation, fish oil produced nutritional preconditioning by prior LCn-3 PUFA incorporation and increased peroxidisability leading to up-regulated mitochondrial SOD antioxidant activity.

The effect of natural antioxidants on the rate of accumulation of oxidation products in the fat phase of butter cream

Describes the main finishing prefabricated pastries and cakes-cream. Researched range of cream depending on the fruit components and method of production. Aim: to study the degree of oxidation cream with natural antioxidants from fruits and berries processing products, namely in the form of concentrated juice of fruits and berries. Outlines the process of oxidation of lipids, one of the fundamental processes of loss of quality food products. Describes the action of antioxidants as antioxidants on accumulation intensity concentrations of primary and secondary oxidation products, making the final product unsuitable for the consumer and the bounding its shelf life. Presents the results of a study of the contents of primary and secondary oxidation products in butter cream immediately after cooking, as well as samples, stored for five days with the addition of antioxidants in the form of concentrated juice of fruits and berries in the amount of 2–7% by weight of cream. As a control sample has been used cream with no additives. Quality indicators to characterize the degree of oxidation of the product: acid, peroxide, anizidin and tioburbit number. The study found that adding a concentrated juice of fruits and berries as antioxidant in recipe cream reduces the growth rate of the concentration of free fatty acids on the fifth day, as compared with the reference sample. Adding concentrated juice of fruits and berries slows down the process of dissolution of the fat molecules in fat fraction of cream with the formation of free fatty acids; intensity decay reaction of peroxides and hydroxides slows down and, consequently, decreases the formation of aldehydes, deteriorating the taste and smell of the cream; quantitatively reduced the growth of education malondial′degida.

The effect of natural antioxidants on the rate of accumulation of oxidation products in the fat phase of butter cream

Describes the main finishing prefabricated pastries and cakes-cream. Researched range of cream depending on the fruit components and method of production. Aim: to study the degree of oxidation cream with natural antioxidants from fruits and berries processing products, namely in the form of concentrated juice of fruits and berries. Outlines the process of oxidation of lipids, one of the fundamental processes of loss of quality food products. Describes the action of antioxidants as antioxidants on accumulation intensity concentrations of primary and secondary oxidation products, making the final product unsuitable for the consumer and the bounding its shelf life. Presents the results of a study of the contents of primary and secondary oxidation products in butter cream immediately after cooking, as well as samples, stored for five days with the addition of antioxidants in the form of concentrated juice of fruits and berries in the amount of 2–7% by weight of cream. As a control sample has been used cream with no additives. Quality indicators to characterize the degree of oxidation of the product: acid, peroxide, anizidin and tioburbit number. The study found that adding a concentrated juice of fruits and berries as antioxidant in recipe cream reduces the growth rate of the concentration of free fatty acids on the fifth day, as compared with the reference sample. Adding concentrated juice of fruits and berries slows down the process of dissolution of the fat molecules in fat fraction of cream with the formation of free fatty acids; intensity decay reaction of peroxides and hydroxides slows down and, consequently, decreases the formation of aldehydes, deteriorating the taste and smell of the cream; quantitatively reduced the growth of education malondial′degida.

Degradation of cable insulation material by accelerated thermal radiation combined ageing

The degradation of ethylene propylene rubber (EPR) sheets as a cable insulation material for nuclear power plants (NPP) was studied by accelerated thermal ageing, radiation ageing and thermal – radiation combined ageing. The oxidation of EPR proceeded with ageing and the decay of mechanical property was closely related to the content of oxidation products. The antioxidant as a stabilizer in EPR was effective for the thermal oxidation, but not for the radiation oxidation. The distribution of oxidation products across the sheet was changed due to decay of antioxidant by evaporation during thermal ageing. The antioxidant was not effective for radiation oxidation, and it was decomposed by radiation. For the thermal and radiation combined oxidation, the mechanical property and the content of oxidation products were different among the treatment sequences, which was due to the decay of antioxidant. The lifetime of EPR cable is closely related to the remaining content of antioxidant, and the lifetime evaluation would be recommended by the reverse sequential combination (thermal ageing after radiation ageing).

Effects of the Dietary Supplementation of Sucupira (Pterodon Emarginatus Vog.) and Copaiba (Copaifera Langsdorffii) Resinoils on Chicken Breast and Thigh Meat Quality and Oxidative Stability

An experiment was conducted to evaluate the addition of the oil resins ofsucupira (Pterodon emarginatus Vog.) and copaiba (Copaifera langsdorffii) to broiler diets on chicken meat composition, quality, and lipid peroxidation. 350 one-d-old broiler chicks were submitted to seven treatments, consisting of the diets supplemented with copaiba (COP) or sucupira (SUC) resin oils at three different concentrations (500, 900, and 1300 ppm) plus a negative control diet (CONT). At 37 days of age, 10 birds per treatment were selected according to the average weight of the experimental unit and slaughtered to collect breast and thigh meat, which was stored at 4°C for 24 hours to evaluate pH, color (L*, a*, b*), cooking weight loss (CWL), and shear force (SF). Raw meat was vacuum packed and stored frozen until lipid peroxidation analysis. Meat samples were pooled to prepare pre-cooked meatballs (30 ± 0.5g), stored under refrigeration (eight days), and analyzed every two days for TBARS concentration. Results were analyzed using the PROC GLM and MIXED procedures (SAS statistical software). Plant oils increased (p<0.05) breast meat humidity (HU) and crude protein (CP) levels and reduced (p<0.05) total lipid (TLC) and ash (AS) levels when compared with the CONT treatment. Plant oils increased (p<0.05) thigh meat HU when compared with the CONT. High COP dietary levels reduced (p<0.05) breast meat CWL, and increased (p<0.05) thigh meat L* values when compared to CONT, except for SUC500 and SUC900. The dietary inclusion of plant oil resins showed a pro-oxidant effect (p<0.01) on breast meat when compared with the CONT. Low SUC dietary supplementation levels significantly reduced (p<0.01) the concentration of secondary oxidation products in thigh meat.

DPP-4 inhibitor sitagliptin prevents inflammation and oxidative stress of heart and kidney in two kidney and one clip (2K1C) rats.

BackgroundHyperglycemia and insulin resistance often develop cardiovascular and nephrological dysfunction in diabetic patients. Sitagliptin is used to treat diabetes and showed potential benefit in lowering increased blood glucose level in diabetes. This investigation reports the effect of sitagliptin treatment on oxidative stress in kidney and heart of 2K1C rats.MethodsMale Long Evans rats underwent unilateral surgical stenosis of the renal artery [2-kidney-1-clip (2K1C) method]. These animals entered a 4-weeks dosing period with sitagliptin. Blood and urine sampling and organ harvesting were finally performed. Blood plasma, heart, kidney tissues and urine were tested for the assessment of inflammation and oxidative stress in kidney and heart of 2K1C rats after 4 weeks of surgery.Results2K1C rats showed cardiac hypertrophy, increased left ventricular wet weight compared to sham which was not significantly altered by sitagliptin treatment. Uric acid and creatinin concentrations were also increased in 2K1C rats. Sitagliptin significantly prevented the elevation of uric acid and creatinin concentration in plasma and urine in this rat model. Oxidative stress markers in plasma such as malondialdehyde (MDA), nitric oxide (NO), and advanced protein oxidation product (APOP) concentrations were increased in the 2K1C rats as compared to sham-operated animals. Increased concentrations of these oxidative stress markers were also normalized by sitagliptin treatment. 2K1C rats also showed increased level of uric acid and creatinine both in plasma and urine; which are also reduced to normal level in sitagliptin treated rats. Moreover, 2K1C surgery initiated inflammatory cell infiltration, increased MPO activity and fibrosis in both heart and kidneys which were further ameliorated by sitagliptin treatment.ConclusionOur study suggests that sitagliptin treatment in 2K1C rats prevented inflammation and fibrosis of heart and kidney by ameliorating elevated oxidative stress in heart and kidney tissues.

Emissions of biogenic volatile organic compounds and subsequent formation of secondary organic aerosols in a &amp;lt;I&amp;gt;Larix kaempferi&amp;lt;/I&amp;gt; forest

Abstract. We conducted simultaneous measurements of concentrations and above-canopy fluxes of isoprene and α-pinene, along with their oxidation products in aerosols in a Larix kaempferi (Japanese larch) forest in summer 2012. Vertical profiles of isoprene showed the maximum concentration near the forest floor with a peak around noon, whereas oxidation products of isoprene, i.e., methacrolein (MACR) and methyl vinyl ketone (MVK), showed higher concentrations near the canopy level of the forest. The vertical profile suggests large emissions of isoprene near the forest floor, likely due to Dryopteris crassirhizoma (a fern species), and the subsequent reaction within the canopy. The concentrations of α-pinene also showed highest values near the forest floor, with maximums in the early morning and late afternoon. The vertical profiles of α-pinene suggest its large emissions from soil and litter in addition to emissions from L. kaempferi leaves at the forest site. Isoprene and its oxidation products in aerosols exhibited similar diurnal variations within the forest canopy, providing evidence of secondary organic aerosol (SOA) formation via oxidation of isoprene most likely emitted from the forest floor. Although high abundance of α-pinene was observed in the morning, its oxidation products in aerosols showed peaks in daytime, due to a time lag between the emission and atmospheric reactions of α-pinene to form SOA. Positive matrix factorization (PMF) analysis indicated that anthropogenic influence is the most important factor contributing to the elevated concentrations of molecular oxidation products of isoprene- (&gt; 64 %) and α-pinene-derived SOA (&gt; 57 %). The combination of the measured fluxes and vertical profiles of biogenic volatile organic compounds (BVOCs) suggests that the inflow of anthropogenic precursors/aerosols likely enhanced the formation of both isoprene SOA and α-pinene SOA within the forest canopy even when the BVOC flux was relatively low. This study highlights the importance of intra-canopy processes that promote biogenic SOA formation in the presence of significant inflow of oxidants together with anthropogenic aerosols and their precursors.

Antioxidant Activity of Date Palm Fruit (Phoenix dactylifera L.) Extract for Oxidative Stabilisation of Butter Oil at Ambient Temperature

In this study, long term preservation of butter oil was achieved through ethanolic extract of date palm fruit (Phoenix dactylifera L.). Butter oil was supplemented with date palm fruit extract (DPFE) at three different concentrations i.e. 250, 500 and 750 ppm (T1, T2 and T3) and compared with a control. Total phenolic content, DPPH free radical scavenging activity and inhibition of linoleic acid peroxidation of the DPFE was 5.19 GAE, 74.2 and 81%, respectively. IC50 value of date extract for the inhibition of DPPH and linoleic acid peroxidation was 2.45 and 0.82 mg/mL, respectively. The loss of oleic acid and linoleic acid in control after six months of storage was 16 and 52% as compared to T3 which was 4% and 14%. T3 yielded the lowest concentration of primary and secondary oxidation products with no effect on sensory attributes. DPFE can be used to enhance the shelf life of butter oil at ambient temperature.

Calculating Equilibrium Phase Distribution during the Formation of Secondary Organic Aerosol Using COSMOtherm.

Challenges in the parametrization of compound distribution between the gas and particle phase contribute significantly to the uncertainty in the prediction of secondary organic aerosol (SOA) formation and are rooted in the complexity and variability of atmospheric condensed matter, which includes water, salts, and a multitude of organic oxidation products, often in two separated phases. Here, we explore the use of the commercial quantum-chemistry-based software COSMOtherm to predict equilibrium partitioning and Setchenow coefficients of a suite of oxidation products of α-pinene ozonolysis in an aerosol that is assumed to separate into an organic-enriched phase and an electrolyte-enriched aqueous phase. The predicted coefficients are used to estimate the phase distribution of the organic compounds, water and ammonium sulfate, the resulting phase composition, and the SOA yield. Four scenarios that differ in terms of organic loading, liquid water content, and chemical aging are compared. The organic compounds partition preferentially to the organic phase rather than the aqueous phase for the studied aerosol scenarios, partially due to the salting-out effect. Extremely low volatile organic compounds are predicted to be the dominant species in the organic aerosols at low loadings and an important component at higher loadings. The highest concentration of oxidation products in the condensed phase is predicted for a scenario assuming the presence of non-phase-separated cloud droplets. Partitioning into an organic aerosol phase composed of the oxidation products is predicted to be similar to partitioning into a phase composed of a single organic surrogate molecule, suggesting that the calculation procedure can be simplified without major loss of accuracy. COSMOtherm is shown to produce results that are comparable to those obtained using group contribution methods. COSMOtherm is likely to have a much larger application domain than those group contribution methods because it is based on fundamental principles with little calibration.

Long-term accelerated weathering of HAS stabilized PE and PP plaques: Compliance of ESRI, IR, and microhardness data characterizing heterogeneity of photooxidation

Polymers in various applications are subjected to photooxidation processes resulting in loss of their material properties due to appearance of oxidation products and consequent degradation. Heterogeneous space distribution of concentration of oxidation products, crystallinity, stabilizer concentration and microhardness (MH) can be determined utilizing IR microspectroscopy and microhardness tester, respectively. We devoted this paper to direct determination of heterogeneity of the above mentioned parameters inside PE polymer plaques stabilized with secondary HAS Tinuvin® 770 and to the comparison of the data with nitroxide concentration profiles determined by ESRI that outline heterogeneity of the oxidation process inside the plaques. Data on heterogeneity of photooxidation processes in PP plaques stabilized with Tinuvin® 770 or binitroxide Prostab® 5415 are presented for comparison.

Cholesterol and stigmasterol within a sunflower oil matrix: Thermal degradation and oxysterols formation

The characteristics of the lipid matrix surrounding sterols exert a great influence in their thermal oxidation process. The objective of this work was to assess the oxidation susceptibility of equal amounts of cholesterol and stigmasterol within a sunflower oil lipid matrix (ratio 1:1:200) during heating (180°C, 0–180min). Remaining percentage of sterols was determined and seven sterol oxidation products (SOPs) were analysed for each type of sterol along the heating treatment. Evolution of the fatty acid profile and vitamin E content of the oil was also studied. Overall oxidation status of the model system was assessed by means of Peroxides Value (PV) and TBARS. PV remained constant from 30min onwards and TBARS continued increasing along the whole heating treatment. Degradation of both cholesterol and stigmasterol fitted a first order curve (R2=0.937 and 0.883, respectively), with very similar degradation constants (0.004min−1 and 0.005min−1, respectively). However, higher concentrations of oxidation products were found from cholesterol (79μg/mg) than from stigmasterol (53μg/mg) at the end of the heating treatment. Profile of individual oxidation products was similar for both sterols, except for the fact that no 25-hydroxystigmasterol was detected. 7α-Hydroxy and 7-keto-derivatives were the most abundant SOPs at the end of the treatment. PUFA and vitamin E suffered a significant degradation along the process, which was correlated to sterols oxidation.

Ozone-initiated terpene reaction products in five European offices: replacement of a floor cleaning agent.

Cleaning agents often emit terpenes that react rapidly with ozone. These ozone-initiated reactions, which occur in the gas-phase and on surfaces, produce a host of gaseous and particulate oxygenated compounds with possible adverse health effects in the eyes and airways. Within the European Union (EU) project OFFICAIR, common ozone-initiated reaction products were measured before and after the replacement of the regular floor cleaning agent with a preselected low emitting floor cleaning agent in four offices located in four EU countries. One reference office in a fifth country did not use any floor cleaning agent. Limonene, α-pinene, 3-carene, dihydromyrcenol, geraniol, linalool, and α-terpineol were targeted for measurement together with the common terpene oxidation products formaldehyde, 4-acetyl-1-methylcyclohexene (4-AMCH), 3-isopropenyl-6-oxo-heptanal (IPOH), 6-methyl-5-heptene-2-one, (6-MHO), 4-oxopentanal (4-OPA), and dihydrocarvone (DHC). Two-hour air samples on Tenax TA and DNPH cartridges were taken in the morning, noon, and in the afternoon and analyzed by thermal desorption combined with gas chromatography/mass spectrometry and HPLC/UV analysis, respectively. Ozone was measured in all sites. All the regular cleaning agents emitted terpenes, mainly limonene and linalool. After the replacement of the cleaning agent, substantially lower concentrations of limonene and formaldehyde were observed. Some of the oxidation product concentrations, in particular that of 4-OPA, were also reduced in line with limonene. Maximum 2 h averaged concentrations of formaldehyde, 4-AMCH, 6-MHO, and IPOH would not give rise to acute eye irritation-related symptoms in office workers; similarly, 6-AMCH, DHC and 4-OPA would not result in airflow limitation to the airways.

Geochemical and Hydrologic Assessment of Drainage from Cherry Valley Coal Mine, Ohio

Drainage from abandoned underground coal mines negatively impacts many miles of stream habitat throughout the Appalachian region. The drainage is commonly called acid mine drainage (AMD) due to its low pH; however, not all mine drainage is acidic. The quantity and quality of the water discharged from a coal mine depend upon numerous variables, such as the design of the mine, chemical composition of the coal and surrounding rocks, and local climate. Coal extracted from the now-abandoned Cherry Valley Coal Mine near Leetonia, Ohio, was reached by a slope entry such that the mine is not entirely up-dip, and a significant area is flooded. Recharge water that enters the unsaturated area of the mine mobilizes soluble iron-sulfate salts as it flows down-dip and adds pyrite oxidation products to the mine pool. The bedrock overburden is covered by calcareous glacial till that imparts alkalinity to the shallow groundwater, buffers the acidity, and keeps the pH inside the mine circumneutral. Maintaining a circumneutral pH reduces pyrite oxidation by decreasing the solubility of ferric iron, the primary oxidizing agent of pyrite at low pH, which reduces the positive feedback mechanism that drives pH down and concentration of oxidation products up. Shallow groundwater is brought to the mine via subsidence fractures, which facilitate a rapid increase in discharge from the mine (and dilution of oxidation products) in response to surface runoff events. The loadings of all dissolved ions, except iron, are controlled by the changes in discharge rather than the changes in concentration.

Alkyl chain length impacts the antioxidative effect of lipophilized ferulic acid in fish oil enriched milk

Lipophilization of phenolics by esterification with fatty alcohols may alter their localization in an emulsion and thereby their antioxidant efficacy. In this study, synthesized unbranched alkyl ferulates were evaluated as antioxidants in fish oil enriched milk. Lipid oxidation was determined by peroxide values and concentration of volatile oxidation products. A cut-off effect in the antioxidant efficacy in relation to the alkyl chain length was observed. The most efficient alkyl ferulate was methyl ferulate followed by ferulic acid and butyl ferulate, whereas octyl ferulate was prooxidative and the prooxidative effect increased further with an increment in the alkyl chain length from C8 to C12. Further elongation of the alkyl chain length to C16 and C20 resulted in weak prooxidative effects to weak antioxidative effects depending on the different volatile oxidation compounds developed.

Omega‐3 supplementation alters mitochondrial membrane composition and respiration kinetics in human skeletal muscle

Studies have shown increased incorporation of omega-3 fatty acids into whole skeletal muscle following supplementation, although little has been done to investigate the potential impact on the fatty acid composition of mitochondrial membranes and the functional consequences on mitochondrial bioenergetics. Therefore, we supplemented young healthy male subjects (n = 18) with fish oils [2 g eicosapentaenoic acid (EPA) and 1 g docosahexanoic acid (DHA) per day] for 12 weeks and skeletal muscle biopsies were taken prior to (Pre) and following (Post) supplementation for the analysis of mitochondrial membrane phospholipid composition and various assessments of mitochondrial bioenergetics. Total EPA and DHA content in mitochondrial membranes increased (P < 0.05) ∼450 and ∼320%, respectively, and displaced some omega-6 species in several phospholipid populations. Mitochondrial respiration, determined in permeabilized muscle fibres, demonstrated no change in maximal substrate-supported respiration, or in the sensitivity (apparent Km) and maximal capacity for pyruvate-supported respiration. In contrast, mitochondrial responses during ADP titrations demonstrated an enhanced ADP sensitivity (decreased apparent Km) that was independent of the creatine kinase shuttle. As the content of ANT1, ANT2, and subunits of the electron transport chain were unaltered by supplementation, these data suggest that prolonged omega-3 intake improves ADP kinetics in human skeletal muscle mitochondria through alterations in membrane structure and/or post-translational modification of ATP synthase and ANT isoforms. Omega-3 supplementation also increased the capacity for mitochondrial reactive oxygen species emission without altering the content of oxidative products, suggesting the absence of oxidative damage. The current data strongly emphasize a role for omega-3s in reorganizing the composition of mitochondrial membranes while promoting improvements in ADP sensitivity.

Increased endoplasmic reticulum stress and Nrf2 repression in peripheral blood mononuclear cells of patients with stable coronary artery disease

Endoplasmic reticulum (ER) stress is involved in the pathophysiology of atherosclerosis. Insults interfering with ER function lead to the accumulation of unfolded and misfolded proteins in the ER that initiates the unfolded protein response (UPR). When the UPR fails to control the level of unfolded and misfolded proteins, ER-initiated apoptotic signaling is induced. We evaluated: (1) the UPR and ER-initiated apoptotic signaling in peripheral blood mononuclear cells (PBMCs) of stable coronary artery disease (CAD) patients; (2) PBMC content of oxidation products of phospholipid 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphorylcholine (oxPAPC); (3) the possible origin of oxPAPC in PBMCs; and (4) the expression of nuclear erythroid-related factor 2 (Nrf2)/antioxidant-related element (ARE), a cellular defense mechanism. Twenty-nine CAD patients and 28 matched controls were enrolled. Expression of glucose-regulated protein 78kDa (GRP78/BiP), as a representative of the UPR, and of C/EBP homologous protein (CHOP), as a representative of ER apoptosis, was significantly higher in CAD than in controls (p<0.01). Concentrations of oxPAPC in PBMCs, in plasma, and in low-density lipoprotein (LDL) were significantly higher in CAD compared to controls (p<0.01). The oxPAPC in PBMCs may derive from circulating ox-LDL. Nrf2/ARE gene expression and circulating and cellular glutathione were significantly lower in CAD compared to controls (p<0.01). In in vitro studies, increasing amounts of oxPAPC induced a dose-dependent increase in CHOP and apoptosis-related protein expression (p<0.01) and a progressive decrease in Nrf2/ARE gene expression (p<0.01). In PBMCs of CAD patients there is an activation of the UPR and ER-initiated apoptotic signaling, possibly related to an abnormal concentration of oxPAPC in PBMCs.

Seasonal cycling and mass-loading of dissolved metals and sulfate discharging from an abandoned mine site in northern Canada

Drainage from sulfide-rich mine waste can contaminate surface waters directly by surface runoff and indirectly through groundwater discharge. The Camp Lake watershed, located in northern Manitoba, receives both direct and indirect drainage from an abandoned tailings impoundment which has resulted in severely degraded water quality. Sulfide oxidation has been occurring for over 70years at an abandoned mine site in this watershed, resulting in high concentrations of oxidation products in the surface water and groundwater discharging from the two tailings impoundments, both of which flow into the adjacent Camp Lake. A 5-year hydrological and geochemical sampling program was conducted at this small Precambrian shield lake prior to the initiation of remedial actions, to identify the seasonal distribution and mass-loading of dissolved metals and sulfate discharging from Camp Lake to the downstream Kississing Lake. Weekly and biweekly sampling of outflow from the lake clearly showed a seasonal cycle of dissolved metals, sulfate and pH. During months when the lake was ice-covered, the discharge water had a neutral pH with low concentrations of dissolved metals and sulfate similar to background concentrations. At spring melt the discharge sampled at Camp Weir revealed abrupt increases in dissolved metal and sulfate concentrations and decreases in pH to values that remained relatively constant until fall freeze-up, when dissolved metal concentrations and pH returned to winter values. The annual and interannual variations in loadings measured at Camp Weir are different from those measured at the two streams feeding Camp Lake showing the contribution of groundwater flow through the tailings to SO4 and metal loadings to the lake during dry years and the potential for significant loadings due to flushing of the thick unsaturated zone in the tailings during relatively wet years. The abrupt changes in pH, metal and sulfate concentrations and the timing of these changes with the appearance and disappearance of ice-cover on the lakes suggests a combination of physical and geochemical controls related to shifts in sources of water, mixing and changes in solubility. Despite fairly low average annual metal concentrations measured in Camp Lake discharge, concentrations of Zn and Cu were elevated above background in bottom sediments of Kississing Lake in a zone extending 9.5km2 from the location of Camp Lake inflow. These results show the importance of the open-water period in controlling metal discharge from mine-impacted areas, and demonstrate that even when average annual concentrations are only slightly elevated, long-term metal loadings can have a significant impact on the receiving aquatic systems.

Express method for determining acid number of lubricating oils for gas-pumping units

A correlation is established experimentally between the content of oxidation products determined by IR spectroscopy and the acid number of lubricating oils used in gas-pumping units. A new express method is proposed fro determining acid number.