Search

Copyright of Austral Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Predators can alter nutrient cycles simply by inducing stress in prey. This stress accelerates prey's protein catabolism, nitrogen waste production, and nitrogen cycling. Yet predators also reduce the feeding rates of their prey, inducing food deprivation that is expected to slow protein catabolism and nitrogen cycling. The physiology of prey under predation risk thus balances the influences of predation risk and food deprivation, and this balance is central to understanding the role of predators in nutrient cycles. We explored the separate and combined effects of predation risk and food deprivation on prey physiology and nutrient cycling by exposing guppies (Poecilia reticulata) to predation risk and food deprivation in a 2 × 2 design. We simulated predation risk using chemical cues from a natural predator of guppies, and we created food deprivation by rationing food availability. We measured guppy response as food consumption, growth, tissue energy density, tissue carbon:nitrogen, and nitrogen (N) excretion and assimilation. We found that N‐linked physiological processes (N consumption, assimilation, excretion) were strongly affected by predation risk, independent of food consumption. Guppies excreted substantially less under predation risk than they did under food deprivation or control conditions. These results suggest that predation risk, per se, triggers physiological changes in guppies that increase N retention and decrease N excretion. We suggest that slower N metabolism under predation risk is an adaptive response that minimizes protein loss in the face of predictable, predator‐induced food restriction. Notably, N metabolism shares common hormonal control with food seeking behavior, and we speculate that increased N retention is a direct and immediate result of reduced food seeking under predation risk. Contrary to predation‐stress‐based hypotheses for how predators affect nutrient cycling by prey, our result indicates that even short‐term exposure to predators may decelerate, rather than accelerate, the speed of N cycling by suppressing N turnover by prey. [ABSTRACT FROM AUTHOR]

Abstract: This study used a damaged skin, porcine model to evaluate the in vivo efficacy of WoundStat™ for the decontamination of superficial, nerve agent‐contaminated wounds. Anaesthetized animals were randomly assigned to either control (n = 7), no decontamination (n = 12) or WoundStat™ (n = 12) treatment groups. Pigs were exposed to a 5× LD50 dose of neat, radiolabelled S‐[2‐(diisopropylamino)ethyl]‐O‐ethyl methyl‐phosphonothioate (VX; or equivalent volume of sterile saline for the control group) via an area of superficially damaged skin on the ear. WoundStat™ was applied at 30 seconds post‐exposure to assigned animals. The VX contaminant (or saline) and decontaminant remained in place for the duration of the study (up to 6 hours). Physiological parameters and signs of intoxication were recorded during the exposure period. Skin and organ samples were taken post mortem for 14C–VX distribution analyses. Blood samples were taken periodically for toxicokinetic and whole‐blood acetylcholinesterase (AChE) activity analyses. VX exposure was accompanied by a rapid decrease in AChE activity in all animals, regardless of decontamination. However, decontamination significantly improved survival rate and time and reduced the severity of signs of intoxication. In addition, the distribution of 14C–VX in key internal organs and post mortem blood samples was significantly lower in the WoundStat™ treatment group. This study demonstrates that WoundStat™ may be a suitable medical countermeasure for increasing both survival rate and time following VX exposure. The results also suggest that AChE activity is not a useful prognostic indicator. [ABSTRACT FROM AUTHOR]

This study used a damaged skin, porcine model to evaluate the in vivo efficacy of WoundStat™ for decontamination of superficial (non-haemorrhaging), sulphur mustard-contaminated wounds. The dorsal skin of 12 female pigs was subjected to controlled physical damage and exposed to 10 μL 14C-radiolabelled sulphur mustard (14C-SM). Animals were randomly assigned to either a control or a treatment group. In the latter, WoundStat™ was applied 30 s post exposure and left in situ for 1 h. Skin lesion progression and decontaminant efficacy were quantified over 6 h using a range of biophysical measurements. Skin, blood and organ samples were taken post mortem for histopathological assessment, 14C-SM distribution and toxicokinetic analyses. Application of SM to damaged skin without decontamination was rapidly followed by advanced signs of toxicity, including ulceration and decreased blood flow at the exposure site in all animals. WoundStat™ prevented ulceration and improved blood flow at the exposure site in all decontaminated animals ( n = 6). Furthermore, significantly smaller quantities of 14C-SM were detected in the blood (45% reduction), and recovered from skin (70% reduction) and skin surface swabs (99% reduction) at 6 h post-challenge. Overall, the distribution of 14C-SM in the internal organs was similar for both groups, with the greatest concentration in the kidneys, followed by the liver and small intestine. WoundStat™ significantly reduced the amount of 14C-SM recovered from the liver, a key organ for SM metabolism and detoxification. This study demonstrates that WoundStat™ is a suitable product for reducing the ingress and toxicity of a chemical warfare agent. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Previous studies have demonstrated that haemostatic products with an absorptive mechanism of action retain their clotting efficiency in the presence of toxic materials and are effective in decontaminating chemical warfare (CW) agents when applied to normal, intact skin. The purpose of this in vitro study was to assess three candidate haemostatic products for effectiveness in the decontamination of superficially damaged porcine skin exposed to the radiolabelled CW agents, soman (GD), VX and sulphur mustard (HD). Controlled physical damage (removal of the upper 100 μm skin layer) resulted in a significant enhancement of the dermal absorption of all three CW agents. Of the haemostatic products assessed, WoundStat™ was consistently the most effective, being equivalent in performance to a standard military decontaminant (fuller's earth). These data suggest that judicious application of haemostatic products to wounds contaminated with CW agents may be a viable option for the clinical management of casualties presenting with contaminated, haemorrhaging injuries. Further studies using a relevant animal model are required to confirm the potential clinical efficacy of WoundStat™ for treating wounds contaminated with CW agents. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The risk of penetrating, traumatic injury occurring in a chemically contaminated environment cannot be discounted. Should a traumatic injury be contaminated with a chemical warfare (CW) agent, it is likely that standard haemostatic treatment options would be complicated by the need to decontaminate the wound milieu. Thus, there is a need to develop haemostatic products that can simultaneously arrest haemorrhage and decontaminate CW agents. The purpose of this study was to evaluate a number of candidate haemostats for efficacy as skin decontaminants against three CW agents (soman, VX and sulphur mustard) using an in vitro diffusion cell containing undamaged pig skin. One haemostatic product (WoundStat™) was shown to be as effective as the standard military decontaminants Fuller's earth and M291 for the decontamination of all three CW agents. The most effective haemostatic agents were powder-based and use fluid absorption as a mechanism of action to sequester CW agent (akin to the decontaminant Fuller's earth). The envisaged use of haemostatic decontaminants would be to decontaminate from within wounds and from damaged skin. Therefore, WoundStat™ should be subject to further evaluation using an in vitro model of damaged skin. Copyright © 2014 Crown copyright. Journal of Applied Toxicology © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The treatment of penetrating, haemorrhaging injuries sustained within a hazardous environment may be complicated by contamination with toxic chemicals. There are currently no specific medical countermeasures for such injuries. Haemostats with an absorbent mechanism of action have the potential to simultaneously stop bleeding and decontaminate wounds. However, a primary requirement of a 'haemostatic decontaminant' is the retention of clotting function in the presence of chemical contaminants. Thus, the aim of this study was to investigate the haemostatic efficacy of seven commercially available haemostats in the presence of toxic chemicals (soman, VX, sulphur mustard, petrol, aviation fuel and motor oil). Clot viscosity was assessed ex vivo using thrombelastography following treatment of pig blood with: (i) toxic chemical; (ii) haemostat; or (iii) haemostat in combination with toxic chemical. Several contaminants (VX, petrol and GD) were found to be pro-haemostatic and none had an adverse effect on the rate with which the test products attained haemostasis. However, the total clot strength for blood treated with certain haemostats in the presence of sulphur mustard, soman and petrol was significantly decreased. Three test products failed to demonstrate haemostatic function in this ex vivo (thrombelastography) model; this was tentatively ascribed to the products achieving haemostasis through a tamponade mechanism of action, which can only be replicated using in vivo models. Overall, this study has identified a number of commercial products that may have potential as haemostatic decontaminants and warrant further investigation to establish their decontaminant efficacy. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Trait evolution can occur in response to anthropogenic alterations to ecosystems and can occur on timescales similar to those of ecological processes suggesting that it could alter ecosystem function. In this study, we characterise the effects of life history evolution on nutrient recycling using the Trinidadian guppy ( Poecilia reticulata) as a model system., Guppy life history traits evolve in response to predation pressure. When predation pressure is removed, guppy population density and average body size of the population also increase. Therefore, the evolution of guppy life histories involves changes in individual traits and demographic characteristics, both of which can alter nutrient recycling. The relative contributions of these variables to guppy-driven nutrient recycling are unknown., We synthesise data from published experiments to disentangle how differences in individual traits, population characteristics and environmental conditions contribute to differences in guppy excretion rates. Individual guppies adapted to the absence of predators [low-predation ( LP) guppies] have lower nitrogen and phosphorus excretion rates than individual guppies adapted to predators [high-predation ( HP) guppies]. However, LP guppy populations excrete twice as much nitrogen as HP populations because of their larger average body size and higher population densities., We compare these findings to guppy excretion data collected from HP and LP sites in four rivers in Trinidad. Phenotypic and population differences in excretion rates are consistent with those observed in the experiments., Our study demonstrates that life history evolution can alter nutrient recycling in freshwater ecosystems. Characterizing the combined effects of traits and demographics is essential for understanding the effects of life history evolution on ecosystem processes. [ABSTRACT FROM AUTHOR]

Human-induced trait change has been documented in freshwater, marine, and terrestrial ecosystems worldwide. These trait changes are driven by phenotypic plasticity and contemporary evolution. While efforts to manage human-induced trait change are beginning to receive some attention, managing its ecological consequences has received virtually none. Recent work suggests that contemporary trait change can have important effects on the dynamics of populations, communities, and ecosystems. Therefore, trait changes caused by human activity may be shaping ecological dynamics on a global scale. We present evidence for important ecological effects associated with human-induced trait change in a variety of study systems. These effects can occur over large spatial scales and impact system-wide processes such as trophic cascades. Importantly, the magnitude of these effects can be on par with those of traditional ecological drivers such as species presence. However, phenotypic change is not always an agent of ecological change; it can also buffer ecosystems against change. Determining the conditions under which phenotypic change may promote vs prevent ecological change should be a top research priority. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the efficacy of a novel barrier cream formulation at reducing the percutaneous toxicity of a 2×LD50 liquid challenge of nerve agent (VX). The study was conducted in vitro and in vivo using the domestic pig. Pretreatment of the (inner ear skin) exposure site with barrier cream eliminated mortality, reduced cholinesterase inhibition and prevented any physiological or biochemical signs of intoxication. In contrast, untreated animals exposed to VX exhibited severe signs of intoxication, near total AChE inhibition and generally died within the (3 hr) exposure period (5/6 animals). Application of the barrier cream caused a significant decrease in the area of skin contaminated by VX. It was tentatively concluded that spreading was predominantly a surface phenomena (possibly mediated by capillary movement of the agent through the microrelief or between hair follicles) with little or no contribution from lateral diffusion within the stratum corneum. There was a disparity between the in vitro and in vivo skin absorption measurements that was ascribed to the absence of systemic clearance in vitro. However, both models indicated a substantial reservoir of VX within the skin, providing a potential strategy for future investigations into“catch-up therapies”. In summary, the novel barrier cream formulation was effective against a 2×LD50 (liquid, percutaneous) dose of VX applied for 3 hr. Further work should be conducted to investigate more pragmatic issues such as optimal reapplication frequency and environmental effects such as temperature and humidity. [ABSTRACT FROM AUTHOR]

Animals can be important in modulating ecosystem-level nutrient cycling, although their importance varies greatly among species and ecosystems. Nutrient cycling rates of individual animals represent valuable data for testing the predictions of important frameworks such as the Metabolic Theory of Ecology ( MTE) and ecological stoichiometry ( ES). They also represent an important set of functional traits that may reflect both environmental and phylogenetic influences. Over the past two decades, studies of animal-mediated nutrient cycling have increased dramatically, especially in aquatic ecosystems. Here we present a global compilation of aquatic animal nutrient excretion rates. The dataset includes 10,534 observations from freshwater and marine animals of N and/or P excretion rates. These observations represent 491 species, including most aquatic phyla. Coverage varies greatly among phyla and other taxonomic levels. The dataset includes information on animal body size, ambient temperature, taxonomic affiliations, and animal body N:P. This data set was used to test predictions of MTE and ES, as described in Vanni and McIntyre (2016; Ecology DOI: ). [ABSTRACT FROM AUTHOR]