Exercise training protects the LDLI subfraction from oxidation susceptibility in an aged human population

Background Exercise training is considered an effective strategy to improve metabolic disease. Despite this, less is known regarding exercise training in the prevention and susceptibility of LDL subfraction oxidation, particularly in an aged population. 
Methods Eleven aged (55 ± 4 yrs) and twelve young (21 ± 2 yrs) participants were randomly separated into an experimental or control group as follows: young exercise (n = 6); young control (n = 6); aged exercise (n = 6) and aged control (n = 5). The participants assigned to the exercise groups performed 12 weeks of moderate intensity (55–65% VO2max) exercise training. Venous blood was extracted at baseline, and 48 h following 12 weeks of exercise and assayed for a range of metabolites associated with lipid composition and lipoprotein susceptibility to oxidation. 
Results Although there was no difference in the oxidation potential (time ½ max) of LDL I, II or III between groups at baseline (p > 0.05), there was an increase in time ½ max for LDL I following exercise within the aged exercise group (p < 0.05). Moreover, α-tocopherol concentration was selectively lower in the aged exercise group, compared to the young exercise at baseline. The lipid composition of LDL I, LDL II, LDL III, VLDL, HDL2, HDL3 and serum lipid hydroperoxides remained unchanged as a function of exercise training and ageing (p > 0.05). 
Conclusion The primary finding of this study demonstrates that adaptations in LDL resistance to oxidation occur following 12 weeks of exercise training in the aged, and this may be of clinical significance, as oxidation of LDL has been implicated in atherosclerosis.

Systemic oxidative-nitrosative-inflammatory stress during acute exercise in hypoxia; implications for microvascular oxygenation and aerobic capacity

New Findings

What is the central question of this study?Exercise performance is limited during hypoxia by a critical reduction in cerebral and skeletal tissue oxygenation. To what extent an elevation in systemic free radical accumulation contributes to microvascular deoxygenation and the corresponding reduction in maximal aerobic capacity remains unknown.What is the main finding and its importance?We show that altered free radical metabolism is not a limiting factor for exercise performance in hypoxia, providing important insight into the fundamental mechanisms involved in the control of vascular oxygen transport.

Exercise performance in hypoxia may be limited by a critical reduction in cerebral and skeletal tissue oxygenation, although the underlying mechanisms remain unclear. We examined whether increased systemic free radical accumulation during hypoxia would be associated with elevated microvascular deoxygenation and reduced maximal aerobic capacity (). Eleven healthy men were randomly assigned single-blind to an incremental semi-recumbent cycling test to determine  in both normoxia (21% O_{2) and hypoxia (12% O2) separated by a week. Continuous-wave near-infrared spectroscopy was employed to monitor concentration changes in oxy- and deoxyhaemoglobin in the left vastus lateralis muscle and frontal cerebral cortex. Antecubital venous blood samples were obtained at rest and at  to determine oxidative (ascorbate radical by electron paramagnetic resonance spectroscopy), nitrosative (nitric oxide metabolites by ozone-based chemiluminescence and 3-nitrotyrosine by enzyme-linked immunosorbent assay) and inflammatory stress biomarkers (soluble intercellular/vascular cell adhesion 1 molecules by enzyme-linked immunosorbent assay). Hypoxia was associated with increased cerebral and muscle tissue deoxygenation and lower  (P < 0.05 versus normoxia). Despite an exercise-induced increase in oxidative–nitrosative–inflammatory stress, hypoxia per se did not have an additive effect (P > 0.05 versus normoxia). Consequently, we failed to observe correlations between any metabolic, haemodynamic and cardiorespiratory parameters (P > 0.05). Collectively, these findings suggest that altered free radical metabolism cannot explain the elevated microvascular deoxygenation and corresponding lower  in hypoxia. Further research is required to determine whether free radicals when present in excess do indeed contribute to the premature termination of exercise in hypoxia.}

Does chemical composition of individual Scots pine trees determine the biodiversity of their associated ground vegetation?

Despite plant secondary metabolites being major determinants of species interactions and ecosystem processes, their role in the maintenance of biodiversity has received little attention. In order to investigate the relationship between chemical and biological diversity in a natural ecosystem, we considered the impact of chemical diversity in individual Scots pine trees (Pinus sylvestris) on species richness of associated ground vegetation. Scots pine trees show substantial genetically determined constitutive variation between individuals in concentrations of a group of secondary metabolites, the monoterpenes. When the monoterpenes of particular trees were assessed individually, there was no relationship with species richness of associated ground flora. However, the chemical diversity of monoterpenes of individual trees was significantly positively associated with the species richness of the ground vegetation beneath each tree, mainly the result of an effect among the non-woody vascular plants. This correlation suggests that the chemical diversity of the ecosystem dominant species has an important role in shaping the biodiversity of the associated plant community. The extent and significance of this effect, and its underlying processes require further investigation.

Photocatalytic degradation of eleven microcystin analogues and nodularin by TiO2 coated glass microspheres

Microcystins and nodularin are toxic cyanobacterial secondary metabolites produced by cyanobacteria that pose a threat to human health in drinking water. Conventional water treatment methods often fail to remove these toxins. Advanced oxidation processes such as TiO2 photocatalysis have been shown to effectively degrade these compounds. A particular issue that has limited the widespread application of TiO2 photocatalysis for water treatment has been the separation of the nanoparticulate power from the treated water. A novel catalyst format, TiO2 coated hollow glass spheres (Photospheres™), is far more easily separated from treated water due to its buoyancy. This paper reports the photocatalytic degradation of eleven microcystin variants and nodularin in water using Photospheres™. It was found that the Photospheres™ successfully decomposed all compounds in 5 minutes or less. This was found to be comparable to the rate of degradation observed using a Degussa P25 material, which has been previously reported to be the most efficient TiO2 for photocatalytic degradation of microcystins in water. Furthermore, it was observed that the degree of initial catalyst adsorption of the cyanotoxins depended on the amino acid in the variable positions of the microcystin molecule. The fastest degradation (2 minutes) was observed for the hydrophobic variants (microcystin-LY, -LW, -LF). Suitability of UV-LEDs as an alternative low energy light source was also evaluated.

Assessment of toxicological interactions of benzene and its primary degradation products (catechol and phenol) using a lux-modified bacterial bioassay

A bacterial bioassay has been developed to assess the relative toxicities of xenobiotics commonly found in contaminated soils, rivers, waters, and ground waters. The assay utilized decline in luminescence of lux- marked Pseudomonas fluorescens on exposure to xenobiotics. Pseudomonas fluorescens is a common bacterium in the terrestrial environment, providing environmental relevance to soil, river, and ground water systems. Three principal environmental contaminants associated with benzene degradation were exposed to the luminescence-marked bacterial biosensor to assess their toxicity individually and in combination. Median effective concentration (EC50) values for decline in luminescence were determined for benzene, catechol, and phenol and were found to be 39.9, 0.77, and 458.6 mg/L, respectively. Catechol, a fungal and bacterial metabolite of benzene, was found to be significantly more toxic to the biosensor than was the parent compound benzene, showing that products of xenobiotic biodegradation may be more toxic than the parent compounds. Combinations of parent compounds and metabolites were found to be significantly more toxic to the bioassay than were the individual compounds themselves. Development of this bioassay has provided a rapid screening system suitable for assessing the toxicity of xenobiotics commonly found in contaminated soil, river, and ground-water environments. The assay can be utilized over a wide pH range and is therefore more applicable to such environmental systems than bioluminescence-based bioassays that utilize marine organisms and can only be applied over a limited pH and salinity range.

Loss of exudates from the roots of perennial ryegrass inoculated with a range of micro-organisms

To determine the effect of microbial metabolites on the release of root exudates from perennial ryegrass, seedlings were pulse labelled with [¹⁴C]-CO₂ in the presence of a range of soil micro-organisms. Microbial inoculants were spatially separated from roots by Millipore membranes so that root infection did not occur. Using this technique, only microbial metabolites affected root exudation. The effect of microbial metabolites on carbon assimilation and distribution and root exudation was determined for 15 microbial species. Assimilation of a pulse label varied by over 3.5 fold, dependent on inoculant. Distribution of the label between roots and shoots also varied with inoculant, but the carbon pool that was most sensitive to inoculation was root exudation. In the absence of a microbial inoculant only 1% of assimilated label was exuded. Inoculation of the microcosms always caused an increase in exudation but the percentage exuded varied greatly, within the range of 3-34%. © 1995 Kluwer Academic Publishers.

Do leaves of plants on phosphorus-impoverished soils contain high concentrations of phenolic defence compounds?

Prominent theories of plant defence have predicted that plants growing on nutrient-poor soils produce more phenolic defence compounds than those on richer soils. Only recently has the Protein Competition Model (PCM) of phenolic allocation suggested that N and P limitation could have different effects because the nutrients are involved in different cellular metabolic processes. 2. We extend the prediction of the PCM and hypothesize that N will have a greater influence on the production of phenolic defensive compounds than P availability, because N limitation reduces protein production and thus competition for phenylalanine, a precursor of many phenolic compounds. In contrast, P acts as a recyclable cofactor in these reactions, allowing protein and hence phenolic production to continue under low P conditions. 3. We test this hypothesis by comparing the foliar concentrations of phenolic compounds in (i) phenotypes of 21 species growing on P-rich alluvial terraces and P-depleted marine terraces in southern New Zealand, and (ii) 87 species growing under similar climates on comparatively P-rich soils in New Zealand vs. P-depleted soils in Tasmania. 4. Foliar P concentrations of plants from the marine terraces were about half those of plants from alluvial soils, and much lower in Tasmania than in New Zealand. However, foliar concentrations of N and phenolic compounds were similar across sites in both comparisons, supporting the hypothesis that N availability is a more important determinant of plant investment in phenolic defensive compounds than P availability. We found no indication that reduced soil P levels influenced plant concentrations of phenolic compounds. There was wide variation in the foliar N and P concentrations among species, and those with low foliar nutrient concentrations produced more phenolics (including condensed tannins). 5. Our study is the first trait comparison extending beyond standard leaf economics to include secondary metabolites related to defence in forest plants, and emphasizes that N and P have different influences on the production of phenolic defence compounds. © 2009 British Ecological Society.

Determination of the Mycotoxin Content in Distiller's Dried Grain with Solubles Using a Multianalyte UHPLC-MS/MS Method

There are more than 300 potential mycotoxins that can contaminate food and feed and cause adverse effects in humans and animals. The data on the co-occurrence of mycotoxins in novel animal feed materials, such as distiller's dried grain with solubles (DDGS), are limited. Thus, a UHPLC-MS/MS method for the quantitation of 77 mycotoxins and other fungal metabolites was used to analyze 169 DDGS samples produced from wheat, maize, and barley and 61 grain samples. All DDGS samples analyzed were contaminated with 13-34 different mycotoxins. Fumonisins were present in all 52 maize DDGS samples (81.0-6890 μg/kg for fumonisin B1), and deoxynivalenol was present in all 99 wheat DDGS samples (39.3-1120 μg/kg). A number of co-occurring mycotoxins were also identified. Due to the high co-occurrence of mycotoxins, routine screening of the animal feed ingredients is highly recommended to allow the highlighted risks to be effectively managed.

Biocontrol agents promote growth of potato pathogens, depending on environmental conditions

There is a pressing need to understand and optimize biological control so as to avoid over-reliance on the synthetic chemical pesticides that can damage environmental and human health. This study focused on interactions between a novel biocontrol-strain, Bacillus sp. JC12GB43, and potato-pathogenic Phytophthora and Fusarium species. In assays carried out in vitro and on the potato tuber, the bacterium was capable of near-complete inhibition of pathogens. This Bacillus was sufficiently xerotolerant (water activity limit for growth = 0.928) to out-perform Phytophthora infestans (~0.960) and challenge Fusarium coeruleum (~0.847) and Fusarium sambucinum (~0.860) towards the lower limits of their growth windows. Under some conditions, however, strain JC12GB43 stimulated proliferation of the pathogens: for instance, Fusarium coeruleum growth-rate was increased under chaotropic conditions in vitro (132 mM urea) by >100% and on tubers (2-M glycerol) by up to 570%. Culture-based assays involving macromolecule-stabilizing (kosmotropic) compatible solutes provided proof-of-principle that the Bacillus may provide kosmotropic metabolites to the plant pathogen under conditions that destabilize macromolecular systems of the fungal cell. Whilst unprecedented, this finding is consistent with earlier reports that fungi can utilize metabolites derived from bacterial cells. Unless the antimicrobial activities of candidate biocontrol strains are assayed over a full range of field-relevant parameters, biocontrol agents may promote plant pathogen infections and thereby reduce crop yields. These findings indicate that biocontrol activity, therefore, ought to be regarded as a mode-of-behaviour (dependent on prevailing conditions) rather than an inherent property of a bacterial strain.

Alzheimer's disease-like pathology has transient effects on the brain and blood metabolome

The pathogenesis of Alzheimer's disease (AD) is complex involving multiple contributing factors. The extent to which AD pathology impacts upon the metabolome is still not understood, nor is it known how disturbances change as the disease progresses. For the first time we have profiled longitudinally (6, 8, 10, 12 and 18 months) both the brain and plasma metabolome of APP/PS1 double transgenic and wild type (WT) mice. A total of 187 metabolites were quantified using a targeted metabolomics methodology. Multivariate statistical analysis produced models that distinguished APP/PS1 from WT mice at 8, 10 and 12 months.Metabolic pathway analysis found perturbed polyamine metabolism in both brain and blood plasma. There were other disturbances in essential amino acids,branched chain amino acids and also in the neurotransmitter serotonin.Pronounced imbalances in phospholipid and acylcarnitine homeostasis was evident in two age groups. AD-like pathology therefore impacts greatly on both the brain and blood metabolomes, although there appears to be a clear temporal sequence whereby changes to brain metabolites precede those in blood.

Inhibition of O-GlcNAc transferase activity reprograms prostate cancer cell metabolism

Metabolic networks are highly connected and complex, but a single enzyme, O-GlcNAc transferase (OGT) can sense the availability of metabolites and also modify target proteins. We show that inhibition of OGT activity inhibits the proliferation of prostate cancer cells, leads to sustained loss of c-MYC and suppresses the expression of CDK1, elevated expression of which predicts prostate cancer recurrence (p=0.00179). Metabolic profiling revealed decreased glucose consumption and lactate production after OGT inhibition. This decreased glycolytic activity specifically sensitized prostate cancer cells, but not cells representing normal prostate epithelium, to inhibitors of oxidative phosphorylation (rotenone and metformin). Intra-cellular alanine was depleted upon OGT inhibitor treatment. OGT inhibitor increased the expression and activity of alanine aminotransferase (GPT2), an enzyme that can be targeted with a clinically approved drug, cycloserine. Simultaneous inhibition of OGT and GPT2 inhibited cell viability and growth rate, and additionally activated a cell death response. These combinatorial effects were predominantly seen in prostate cancer cells, but not in a cell-line derived from normal prostate epithelium. Combinatorial treatments were confirmed with two inhibitors against both OGT and GPT2. Taken together, here we report the reprogramming of energy metabolism upon inhibition of OGT activity, and identify synergistically lethal combinations that are prostate cancer cell specific.

A validated UPLC–MS/MS method for the surveillance of ten aquatic biotoxins in European brackish and freshwater systems

Over the past few decades, there has been an increased frequency and duration of cyanobacterial Harmful Algal Blooms (HABs) in freshwater systems globally. These can produce secondary metabolites called cyanotoxins, many of which are hepatotoxins, raising concerns about repeated exposure through ingestion of contaminated drinking water or food or through recreational activities such as bathing/ swimming. An ultra-performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS) multi-toxin method has been developed and validated for freshwater cyanotoxins; microcystins-LR, -YR, -RR, -LA, -LY and -LF, nodularin, cylindrospermopsin, anatoxin-a and the marine diatom toxin domoic acid. Separation was achieved in around 9 min and dual SPE was incorporated providing detection limits of between 0.3 and 5.6 ng/L of original sample. Intra- and inter-day precision analysis showed relative
standard deviations (RSD) of 1.2–9.6% and 1.3–12.0% respectively. The method was applied to the analysis of aquatic samples (n = 206) from six European countries. The main class detected were the hepatotoxins; microcystin-YR (n = 22), cylindrospermopsin (n = 25), microcystin-RR (n = 17), microcystin-LR (n = 12), microcystin-LY (n = 1), microcystin-LF (n = 1) and nodularin (n = 5). For microcystins, the levels detected ranged from 0.001 to 1.51 mg/L, with two samples showing combined levels above the guideline set by the WHO of 1 mg/L for microcystin-LR. Several samples presented with multiple toxins indicating the potential for synergistic effects and possibly enhanced toxicity. This is the first published pan European survey of freshwater bodies for multiple biotoxins, including two identified for the first time; cylindrospermopsin in Ireland and nodularin in Germany, presenting further incentives for improved monitoring and development of strategies to mitigate human exposure.

Nicotinamide Riboside Is a Major NAD+ Precursor Vitamin in Cow Milk

Background: Nicotinamide riboside (NR) is a recently discovered NAD+ precursor vitamin with a unique biosynthetic pathway. Although the presence of NR in cow milk has been known for more than a decade, the concentration of NR with respect to the other NAD+ precursors was unknown.

Objective: We aimed to determine NAD+ precursor vitamin concentration in raw samples of milk from individual cows and from commercially available cow milk.

Methods: LC tandem mass spectrometry and isotope dilution technologies were used to quantify NAD+ precursor vitamin concentration and to measure NR stability in raw and commercial milk. Nuclear magnetic resonance (NMR) spectroscopy was used to test for NR binding to substances in milk.

Results: Cow milk typically contained ∼12 μmol NAD+ precursor vitamins/L, of which 60% was present as nicotinamide and 40% was present as NR. Nicotinic acid and other NAD+ metabolites were below the limits of detection. Milk from samples testing positive for Staphylococcus aureus contained lower concentrations of NR (Spearman ρ = −0.58, P = 0.014), and NR was degraded by S. aureus. Conventional milk contained more NR than milk sold as organic. Nonetheless, NR was stable in organic milk and exhibited an NMR spectrum consistent with association with a protein fraction in skim milk.

Conclusions: NR is a major NAD+ precursor vitamin in cow milk. Control of S. aureus may be important to preserve the NAD+ precursor vitamin concentration of milk.