The impacts of Marcellus Shale gas drilling accidents on amphibians in a Pennsylvania fen

Wetlands Ecology and Management - Gas drilling into the Marcellus Shale play has been linked to environmental issues, including potential impacts on wildlife. In 2009, three separate accidents...     

The use of preserved tissue in finite element modelling of fresh ovine vertebral behaviour

The aim of this study was to investigate whether the predicted finite element (FE) stiffness of vertebral bone is altered when using images of preserved rather than fresh tissue to generate specimen-specific FE models. Fresh ovine vertebrae were used to represent embalmed (n = 3) and macerated dry-bone (n = 3) specimens and treated accordingly. Specimens were scanned pre- and post-treatment using micro-computed tomography. A constant threshold level derived from these images was used to calculate the respective bone volume fraction (BV/TV) from which the conversion factor validated for fresh tissue was used to determine material properties that were assigned to corresponding FE models. Results showed a definite change in the BV/TV between the fresh and the preserved bone. However, the changes in the predicted FE stiffness were not generally greater than the variations expected from assignment of loading and boundary conditions. In conclusion, images of preserved tissue can be used to generate FE models that are representative of fresh tissue with a tolerable level of error.     

Effect of Chronic Pain on Fentanyl Self-Administration in Mice

The development of opioid addiction in subjects with established chronic pain is an area that is poorly understood. It is critically important to clearly understand the neurobiology associated with propensity toward conversion to addiction under conditions of chronic pain. To pose the question whether the presence of chronic pain influences motivation to self-administer opioids for reward, we applied a combination of rodent models of chronic mechanical hyperalgesia and opioid self-administration. We studied fentanyl self-administration in mice under three conditions that induce chronic mechanical hyperalgesia: inflammation, peripheral nerve injury, and repeated chemotherapeutic injections. Responding for fentanyl was compared among these conditions and their respective standard controls (naïve condition, vehicle injection or sham surgery). Acquisition of fentanyl self-administration behavior was reduced or absent in all three conditions of chronic hyperalgesia relative to control mice with normal sensory thresholds. To control for potential impairment in ability to learn the lever-pressing behavior or perform the associated motor tasks, all three groups were evaluated for acquisition of food-maintained responding. In contrast to the opioid, chronic hyperalgesia did not interfere with the reinforcing effect of food. These studies indicate that the establishment of chronic hyperalgesia is associated with reduced or ablated motivation to seek opioid reward in mice.     

Contributions of astrocytes to epileptogenesis following status epilepticus: Opportunities for preventive therapy?

Status epilepticus (SE) is a life threatening condition that often precedes the development of epilepsy. Traditional treatments for epilepsy have been focused on targeting neuronal mechanisms contributing to hyperexcitability, however, approximately 30% of patients with epilepsy do not respond to existing neurocentric pharmacotherapies. A growing body of evidence has demonstrated that profound changes in the morphology and function of astrocytes accompany SE and persist in epilepsy. Astrocytes are increasingly recognized for their diverse roles in modulating neuronal activity, and understanding the changes in astrocytes following SE could provide important clues about the mechanisms underlying seizure generation and termination. By understanding the contributions of astrocytes to the network changes underlying epileptogenesis and the development of epilepsy, we will gain a greater appreciation of the contributions of astrocytes to dynamic circuit changes, which will enable us to develop more successful therapies to prevent and treat epilepsy. This review summarizes changes in astrocytes following SE in animal models and human temporal lobe epilepsy and addresses the functional consequences of those changes that may provide clues to the process of epileptogenesis.     

Medical and Social Determinants of Subsequent Labour Market Marginalization in Young Hospitalized Suicide Attempters

Background

Individuals with a history of suicide attempt have a high risk for subsequent labour market marginalization. This study aimed at assessing the effect of individual and parental factors on different measures of marginalization.

Methods

Prospective cohort study based on register linkage of 5 649 individuals who in 1994 were 16–30 years old, lived in Sweden and were treated in inpatient care for suicide attempt during 1992–1994. Hazard ratios (HRs) for labour market marginalization defined as long-term unemployment (>180 days), sickness absence (>90 days), or disability pension in 1995–2010 were calculated with Cox regression.

Results

Medical risk factors, particularly any earlier diagnosed specific mental disorders (e.g., schizophrenia: HR 5.4 (95% CI: 4.2, 7.0), personality disorders: HR 3.9, 95% CI: 3.1, 4.9), repetitive suicide attempts (HR 1.6, 95% CI: 1.4, 1.9) were associated with a higher relative risk of disability pension. Individual medical factors were of smaller importance for long-term sickness absence, and of only marginal relevance to long-term unemployment. Country of birth outside Europe had an opposite effect on disability pension (HR 0.6, 95% CI: 0.4, 0.8) and long-term unemployment (HR 1.5, 95% CI: 1.3, 1.8). Female sex was positively correlated with long-term sickness absence (HR 1.6, 95% CI: 1.4, 1.7), and negatively associated with long-term unemployment (HR: 0.8, 95% CI: 0.7, 0.9).

Conclusions

As compared to disability pension, long-term sickness absence and unemployment was more strongly related to socio-economic variables. Marginalization pathways seemed to vary with migration status and sex. These findings may contribute to the development of intervention strategies which take the individual risk for marginalization into account.     

Fine scale patterns of migration and gene flow in the endangered mound spring snail, <Emphasis Type="Italic">Fonscochlea accepta</Emphasis> (Mollusca:Hydrobiidae) in arid Australia

Naturally patchy ecosystems are models for other systems currently undergoing anthropogenic habitat fragmentation. Understanding patterns of gene flow in these model systems can help us manage species and ecosystems threatened by human impacts. The mound springs of central Australia represent such a natural model ecosystem, supporting a unique aquatic fauna distributed within an inhospitable arid landscape. Moreover, these springs are being impacted by over extraction of groundwater, providing a unique opportunity to look at dispersal in a patchy habitat that is changing. The present study represents the first fine scale analysis of gene flow under different scenarios of habitat connectivity for the endangered mound spring snail, Fonscochlea accepta. Within a single spring group pairwise estimates of F _ST between springs were very low (ave 0.015) with no association found between genetic distance and a series of geographical distance matrices based on the degree of habitat connectivity among the springs: results implying unstructured dispersal and limited population isolation. However, results from Bayesian assignment tests showed that on average approximately 97% of snails were assigned to their spring of origin. In a preliminary analysis at broader geographic scales (among spring groups) the results from F _ST estimates, Mantel correlation analyses and assignment tests all suggest much stronger and geographically correlated population structuring. While varying results from F-statistics and Bayesian analyses stem from the different information they utilise, together they provide data on contemporary and historical estimates of gene flow and the influence of landscape dynamics on the spatial genetic patterning of the springs.     

Can environmental flows moderate riparian invasions? The influence of seedling morphology and density on scour losses in experimental floods

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Stimulation of intestinal secretion of apolipoprotein AI by triiodothyronine

Rats were made hyperthyroid with triiodothyronine in an osmotic minipump implanted intraperitoneally for one week. Intestinal lymph was collected from euthyroid and hyperthyroid rats for 40-55 hours. The rate of apolipoprotein AI (apo AI) secreted into the lymph by hyperthyroid rats exceeded that of euthyroid rats (149 +/- 9 vs 95 +/- 2 micrograms/hr), and was not associated with a proportional increase in the output of triglyceride. The fall in plasma concentration of apoAI in the euthyroid (10 mg/dl) and hyperthyroid (23 mg/dl) could be accounted for by the loss due to diversion of lymph. It appears that the intestine may contribute significantly to the increased plasma levels of apoAI observed in the hyperthyroid rats.