Polyaromatic hydrocarbons and elements in sediments associated with a suburban railway.

Railroad operations are a potential source for contamination of aquatic ecosystems. We examined concentrations of polyaromatic hydrocarbons (PAHs) and selected elements in sediments collected during 2009-2011 from streams, ditches, or ponds bisected or bordered by the former Elgin, Joliet, and Eastern rail line in the western Chicago, Illinois, metropolitan area. Summed PAH concentrations were greater in sediments collected downstream than in those collected upstream of the railroad and were negatively associated with distance within 500 m of the tracks. Phenanthrene and dibenzo (a,h)anthracene concentrations at some locations exceeded probable effect thresholds for risks to aquatic life. Although maximum levels of chromium (Cr) were below levels of concern, we did not determine the valence state of Cr; thus, risks to aquatic life could not be fully evaluated. Nickel and mercury concentrations exceeded lower effect levels, and vanadium concentrations exceeded chronic toxicity thresholds at some locations, although we did not detect an association between these elements and the presence of the railroad. Lead and arsenic concentrations were greater in proximity to the railroad; however, concentrations were below thresholds of concern for aquatic life. Our results suggest that the railroad and associated activities are contributing some environmental contaminants to waterways in close proximity to it, particularly in a downstream direction. Risks to aquatic life may be greater than implied by observed concentrations of individual contaminants, as synergistic adverse effects are likely to occur with exposure to complex mixtures.

Towards optimising experimental quantification of persistent pain in Parkinson's disease using psychophysical testing.

People with Parkinson's disease (PD) may live for multiple decades after diagnosis. Ensuring that effective healthcare provision is received across the range of symptoms experienced is vital to the individual's wellbeing and quality of life. As well as the hallmark motor symptoms, PD patients may also suffer from non-motor symptoms including persistent pain. This type of pain (lasting more than 3 months) is inconsistently described and poorly understood, resulting in limited treatment options. Evidence-based pain remedies are coming to the fore but therapeutic strategies that offer an improved analgesic profile remain an unmet clinical need. Since the ability to establish a link between the neurodegenerative changes that underlie PD and those that underlie maladaptive pain processing leading to persistent pain could illuminate mechanisms or risk factors of disease initiation, progression and maintenance, we evaluated the latest research literature seeking to identify causal factors underlying persistent pain in PD through experimental quantification. The majority of previous studies aimed to identify neurobiological alterations that could provide a biomarker for pain/pain phenotype, in PD cohorts. However heterogeneity of patient cohorts, result outcomes and methodology between human psychophysics studies overwhelmingly leads to inconclusive and equivocal evidence. Here we discuss refinement of pain-PD paradigms in order that future studies may enhance confidence in the validity of observed effect sizes while also aiding comparability through standardisation. Encouragingly, as the field moves towards cross-study comparison of data in order to more reliably reveal mechanisms underlying dysfunctional pain processing, the potential for better-targeted treatment and management is high.