The effect of malondialdehyde is modified by simian virus 40 transformation in human lung fibroblast cells

The effects of malondialdehyde (MDA), a product of oxidative stress, on normal lung fibroblast cells (MRC5) and transformed c ells (MRC5 SV2) showed differing responses between the two cell lines. MRC5 cells showed lower viability at low MDA concentrations (<250 µM) but had better viability at higher concentrations than the transformed cells. Both cell lines showed an increase in the number of micronuclei, nuclear size and a relocation of p53 to the nucleus with increasing MDA. The expression of p53 was higher in the MRC5 cells at 24 h; 2-8 fold induction vs 1-2.5 fold in the MRC5 SV2 cells, but reduced to almost zero at 48 h in the MRC5 cells. Mutation sequencing of the PCR products of a 689 bp region (residues 4640-5328) of the TP53 gene revealed MRC5 had more mutations than MRC5 SV2 cells (n = 21 and 11 respectively) and that they were predominantly insertions (MRC5 81%, MRC5 SV2 100%). A common mutation was observed in both cell lines; a G insertion at residue 4724 (n = 7) which could prove to be a mutational hotspot. These results indicate that the transformed cells are slower to respond to oxidative stress and/or mutagenic compounds. The mutation spectrum of predominantly frameshift mutations (insertions) suggests that oxidative stress plays a minimal role in smoking related lung cancer, but could be of greater importance to other lung diseases and cancer caused by exposures such as passive smokers, passive vapers and atmospheric pollutants

Quantitative analysis of malondialdehyde-guanine adducts in genomic DNA samples by liquid chromatography tandem mass spectrometry.

RATIONALE: The lipid peroxidation product malondialdehyde forms M1 dG adducts with guanine bases in genomic DNA. The analysis of these adducts is important as a biomarker of lipid peroxidation, oxidative stress and inflammation which may be linked to disease risk or exposure to a range of chemicals. METHODS: Genomic DNA samples were subjected to acid hydrolysis to release the adducts in the base form (M1 G) alongside the other purines. A liquid chromatography-mass spectrometry method was optimised for the quantitation of the M1 G adducts in genomic DNA samples using product ion and multiple reaction mode scans. RESULTS: Product ion scans revealed four product ions from the precursor ion; m/z 188 → 160, 133, 106 and 79. The two smallest ions have not been observed previously and optimisation of the method revealed that these gave better sensitivity (LOQ m/z 79: 162 adducts per 10(7) nucleotides; m/z 106: 147 adducts per 10(7) nucleotides) than the other two ions. An MRM method gave similar sensitivity but the two smallest product ions gave better accuracy (94-95%). Genomic DNA treated with malondialdehyde showed a linear dose-response relationship. CONCLUSION: A fast reliable sample preparation method was used to release adducts in the base form rather than the nucleoside. The methods were optimised to selectively analyse the adducts in the presence of other DNA bases without the need for further sample clean-up. Analysis of genomic DNA gave results consistent with previous work and was applied to new samples. Thus, the method is suitable for the analysis of M1 (d)G adducts in biological samples

Hypothalamic actions of neuromedin U.

The central nervous system and gut peptide neuromedin U (NMU) inhibits feeding after intracerebroventricular injection. This study explored the hypothalamic actions of NMU on feeding and the hypothalamo-pituitary-adrenal axis. Intraparaventricular nucleus (intra-PVN) NMU dose-dependently inhibited food intake, with a minimum effective dose of 0.1 nmol and a robust effect at 0.3 nmol. Feeding inhibition was mapped by NMU injection into eight hypothalamic areas. NMU (0.3 nmol) inhibited food intake in the PVN (0-1 h, 59 ± 6.9% of the control value; P < 0.001) and arcuate nucleus (0-1 h, 76 ± 10.4% of the control value; P < 0.05). Intra-PVN NMU markedly increased grooming and locomotor behavior and dose-dependently increased plasma ACTH (0.3 nmol NMU, 24.8 ± 1.9 pg/ml; saline, 11.4 ± 1.0; P < 0.001) and corticosterone (0.3 nmol NMU, 275.4 ± 40.5 ng/ml; saline, 129.4 ± 25.0; P < 0.01). Using hypothalamic explants in vitro, NMU stimulated CRH (100 nM NMU, 5.9 ± 0.95 pmol/explant; basal, 3.8 ± 0.39; P < 0.01) and arginine vasopressin release (100 nM NMU, 124.5 ± 21.8 fmol/explant; basal, 74.5 ± 7.6; P < 0.01). Leptin stimulated NMU release (141.9 ± 20.4 fmol/explant; basal, 92.9 ± 9.4; P < 0.01). Thus, we describe a novel role for NMU in the PVN to stimulate the hypothalamo-pituitary-adrenal axis and locomotor and grooming behavior and to inhibit feeding

Atomic transition frequencies, isotope shifts, and sensitivity to variation of the fine structure constant for studies of quasar absorption spectra

Theories unifying gravity with other interactions suggest spatial and temporal variation of fundamental "constants" in the Universe. A change in the fine structure constant, alpha, could be detected via shifts in the frequencies of atomic transitions in quasar absorption systems. Recent studies using 140 absorption systems from the Keck telescope and 153 from the Very Large Telescope, suggest that alpha varies spatially. That is, in one direction on the sky alpha seems to have been smaller at the time of absorption, while in the opposite direction it seems to have been larger. To continue this study we need accurate laboratory measurements of atomic transition frequencies. The aim of this paper is to provide a compilation of transitions of importance to the search for alpha variation. They are E1 transitions to the ground state in several different atoms and ions, with wavelengths ranging from around 900 - 6000 A, and require an accuracy of better than 10^{-4} A. We discuss isotope shift measurements that are needed in order to resolve systematic effects in the study. The coefficients of sensitivity to alpha-variation (q) are also presented.Comment: Includes updated version of the "alpha line" lis

Scoping review to identify potential non-antimicrobial interventions to mitigate antimicrobial resistance in commensal enteric bacteria in North American cattle production systems

A scoping review was conducted to identify modifiable non-antimicrobial factors to reduce the occurrence of antimicrobial resistance in cattle populations. Searches were developed to retrieve peer-reviewed published studies in animal, human and in vitro microbial populations. Citations were retained when modifiable non-antimicrobial factors or interventions potentially associated with antimicrobial resistance were described. Studies described resistance in five bacterial genera, species or types, and 40 antimicrobials. Modifiable non-antimicrobial factors or interventions ranged widely in type, and the depth of evidence in animal populations was shallow. Specific associations between a factor or intervention with antimicrobial resistance in a population (e.g. associations between organic systems and tetracycline susceptibility in E. coli from cattle) were reported in a maximum of three studies. The identified non-antimicrobial factors or interventions were classified into 16 themes. Most reported associations between the non-antimicrobial modifiable factors or interventions and antimicrobial resistance were not statistically significant (P > 0·05 and a confidence interval including 1), but when significant, the results were not consistent in direction (increase or decrease in antimicrobial resistance) or magnitude. Research is needed to better understand the impacts of promising modifiable factors or interventions on the occurrence of antimicrobial resistance before any recommendations can be offered or adopted

Stroke increases ischemia-related decreases in motor unit discharge rates

Following stroke, hyperexcitable sensory pathways, such as the group III/IV afferents that are sensitive to ischemia, may inhibit paretic motor neurons during exercise. We quantified the effects of whole leg ischemia on paretic vastus lateralis motor unit firing rates during submaximal isometric contractions. Ten chronic stroke survivors (>1 yr poststroke) and 10 controls participated. During conditions of whole leg occlusion, the discharge timings of motor units were identified from decomposition of high-density surface electromyography signals during repeated submaximal knee extensor contractions. Quadriceps resting twitch responses and near-infrared spectroscopy measurements of oxygen saturation as an indirect measure of blood flow were made. There was a greater decrease in paretic motor unit discharge rates during the occlusion compared with the controls (average decrease for stroke and controls, 12.3 ± 10.0% and 0.1 ± 12.4%, respectively; P < 0.001). The motor unit recruitment thresholds did not change with the occlusion (stroke: without occlusion, 11.68 ± 5.83%MVC vs. with occlusion, 11.11 ± 5.26%MVC; control: 11.87 ± 5.63 vs. 11.28 ± 5.29%MVC). Resting twitch amplitudes declined similarly for both groups in response to whole leg occlusion (stroke: 29.16 ± 6.88 vs. 25.75 ± 6.78 Nm; control: 38.80 ± 13.23 vs 30.14 ± 9.64 Nm). Controls had a greater exponential decline (lower time constant) in oxygen saturation compared with the stroke group (stroke time constant, 22.90 ± 10.26 min vs. control time constant, 5.46 ± 4.09 min; P < 0.001). Ischemia of the muscle resulted in greater neural inhibition of paretic motor units compared with controls and may contribute to deficient muscle activation poststroke. NEW & NOTEWORTHY Hyperexcitable inhibitory sensory pathways sensitive to ischemia may play a role in deficient motor unit activation post stroke. Using high-density surface electromyography recordings to detect motor unit firing instances, we show that ischemia of the exercising muscle results in greater inhibition of paretic motor unit firing rates compared with controls. These findings are impactful to neurophysiologists and clinicians because they implicate a novel mechanism of force-generating impairment poststroke that likely exacerbates baseline weakness

Garden varieties: how attractive are recommended garden plants to butterflies?

One way the public can engage in insect conservation is through wildlife gardening, including the growing of insect-friendly flowers as sources of nectar. However, plant varieties differ in the types of insects they attract. To determine which garden plants attracted which butterflies, we counted butterflies nectaring on 11 varieties of summer-flowering garden plants in a rural garden in East Sussex, UK. These plants were all from a list of 100 varieties considered attractive to British butterflies, and included the five varieties specifically listed by the UK charity Butterfly Conservation as best for summer nectar. A total of 2659 flower visits from 14 butterfly and one moth species were observed. We performed a principal components analysis which showed contrasting patterns between the species attracted to Origanum vulgare and Buddleia davidii. The “butterfly bush” Buddleia attracted many nymphalines, such as the peacock, Inachis io, but very few satyrines such as the gatekeeper, Pyronia tithonus, which mostly visited Origanum. Eupatorium cannibinum had the highest Simpson’s Diversity score of 0.75, while Buddleia and Origanum were lower, scoring 0.66 and 0.50 respectively. No one plant was good at attracting all observed butterfly species, as each attracted only a subset of the butterfly community. We conclude that to create a butterfly-friendly garden, a variety of plant species are required as nectar sources for butterflies. Furthermore, garden plant recommendations can probably benefit from being more precise as to the species of butterfly they attract