Cumulative or sequential assessment during hermit crab shell fights: effects of oxygen on decision rules

Agonistic interactions between animals are often settled by the use of repeated signals which advertise the resource-holding potential of the sender. According to the sequential assessment game this repetition increases the accuracy with which receivers may assess the signal, but under the cumulative assessment model the repeated performances accumulate to give a signal of stamina. These models may be distinguished by the temporal pattern of signalling they predict and by the decision rules used by the contestants. Hermit crabs engage in shell fights over possession of the gastropod shells that they inhabit. During these interactions the two roles of signaller and receiver may be examined separately because they are fixed for the duration of the encounter. Attackers rap their shell against that of the defender in a series of bouts whereas defenders remain tightly withdrawn into their shells for the duration of the contest. At the end of a fight the attacker may evict the defender from its shell or decide to give up without first effecting an eviction; the decision for defenders is either to maintain a grip on its shell or to release the shell and allow itself to be evicted. We manipulated fatigue levels separately for attackers and defenders, by varying the oxygen concentration of the water that they are held in prior to fighting, and examined the effects that this has on the likelihood of each decision and on the temporal pattern of rapping. We show that the vigour of rapping and the likelihood of eviction are reduced when the attacker is subjected to low oxygen but that this treatment has no effect on rates of eviction when applied to defenders. We conclude that defenders compare the vigour of rapping with an absolute threshold rather than with a relative threshold when making their decision. The data are compatible with the cumulative assessment model and with the idea that shell rapping signals the stamina of attackers, but do not fit the predictions of the sequential assessment game.

A pilot study to develop an assessment tool for sheep welfare after long journey transport

Sheep transport within Europe involves 9.5 million animals yearly, 63% of which travel over longjourneys (> 8 h). Livestock transport, particularly over long journeys, gives rise to concern about the welfare of transported animals. The European Commission stimulates the development of market-oriented animal welfare standards for all phases of livestock production, providing an alternative to the 'regulatory approach'. This study aimed to develop and test a new sheep welfare assessment protocol to be used following transport, irrespective of the journey purpose. The protocol included outcome (animal-based measures) and input variables (resource-based and management-based measures), being welfare-relevant aspects of both transport and unloading procedures. Weighted Cohen's Kappa and Heiss' Kappa index of agreement were calculated to evaluate the raters accuracy and the inter-observer reliability.Overall, good agreement levels were found. The protocol was tested on 40 commercial transports arriving at previously selected assembly centres and slaughterhouses in Italy and Greece. The protocol was found to be feasible when applied to commercial transports, allowing for a comprehensive and quick sheep welfare assessment during unloading, without impairing stockman work. Univariate analysis was carried out to evaluate associations between outcome and input variables. In this study, significant association between outcome measures and risk factors were identified when associated to unloading procedures but not to travel conditions. In collaboration with the relevant stakeholders, this protocol might be developed into a tool for routine checks for certification purposes and could provide direct feedback to all professionals involved in animal transportation on the weaknesses and strengths of their work.

Extracellular cathepsin S and intracellular caspase 1 activation are surrogate biomarkers of particulate-induced lysosomal disruption in macrophages

BACKGROUND: Particulate matter has been shown to stimulate the innate immune system and induce acute inflammation. Therefore, while nanotechnology has the potential to provide therapeutic formulations with improved efficacy, there are concerns such pharmaceutical preparations could induce unwanted inflammatory side effects. Accordingly, we aim to examine the utility of using the proteolytic activity signatures of cysteine proteases, caspase 1 and cathepsin S (CTSS), as biomarkers to assess particulate-induced inflammation.

METHODS: Primary peritoneal macrophages and bone marrow-derived macrophages from C57BL/6 mice and ctss(-/-) mice were exposed to micro- and nanoparticulates and also the lysosomotropic agent, L-leucyl-L-leucine methyl ester (LLOME). ELISA and immunoblot analyses were used to measure the IL-1β response in cells, generated by lysosomal rupture. Affinity-binding probes (ABPs), which irreversibly bind to the active site thiol of cysteine proteases, were then used to detect active caspase 1 and CTSS following lysosomal rupture. Reporter substrates were also used to quantify the proteolytic activity of these enzymes, as measured by substrate turnover.

RESULTS: We demonstrate that exposure to silica, alum and polystyrene particulates induces IL-1β release from macrophages, through lysosomal destabilization. IL-1β secretion positively correlated with an increase in the proteolytic activity signatures of intracellular caspase 1 and extracellular CTSS, which were detected using ABPs and reporter substrates. Interestingly IL-1β release was significantly reduced in primary macrophages from ctss(-/-) mice.

CONCLUSIONS: This study supports the emerging significance of CTSS as a regulator of the innate immune response, highlighting its role in regulating IL-1β release. Crucially, the results demonstrate the utility of intracellular caspase 1 and extracellular CTSS proteolytic activities as surrogate biomarkers of lysosomal rupture and acute inflammation. In the future, activity-based detection of these enzymes may prove useful for the real-time assessment of particle-induced inflammation and toxicity assessment during the development of nanotherapeutics.

Self-assessment by males during energetically costly contests over precopula females in amphipods

In animal contests, individuals can either engage in mutual assessment of both their own and their opponent's resource-holding potential (RHP) and adjust their behaviour according to estimated differences, or instead persist in accordance with thresholds determined by assessment of just their own RHP. We examined the predictions of alternative mutual assessment and self-assessment models for decision rules in contest resolution during struggles between males over females in precopula in the amphipod Gammarus pulex. Contest duration was positively related to the weight of the loser but not the weight of the winner. Our results support the hypothesis that males rely on information about their own RHP in determining contest behaviour and do not use information about their opponent. Fighting was energetically costly, and energy reserves were depleted during contests. Contest duration was associated with the physiological state of the loser (but not the winner) at the end of the contest, and to a lesser extent his size, further supporting self-assessment. (c) 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Assessment of the impedance cardiogram recorded by an automated external defibrillator during clinical cardiac arrest

OBJECTIVE: To assess the impedance cardiogram recorded by an automated external defibrillator during cardiac arrest to facilitate emergency care by lay persons. Lay persons are poor at emergency pulse checks (sensitivity 84%, specificity 36%); guidelines recommend they should not be performed. The impedance cardiogram (dZ/dt) is used to indicate stroke volume. Can an impedance cardiogram algorithm in a defibrillator determine rapidly circulatory arrest and facilitate prompt initiation of external cardiac massage?

DESIGN: Clinical study.

SETTING: University hospital.

PATIENTS: Phase 1 patients attended for myocardial perfusion imaging. Phase 2 patients were recruited during cardiac arrest. This group included nonarrest controls.

INTERVENTIONS: The impedance cardiogram was recorded through defibrillator/electrocardiographic pads oriented in the standard cardiac arrest position.

MEASUREMENTS AND MAIN RESULTS: Phase 1: Stroke volumes from gated myocardial perfusion imaging scans were correlated with parameters from the impedance cardiogram system (dZ/dt(max) and the peak amplitude of the Fast Fourier Transform of dZ/dt between 1.5 Hz and 4.5 Hz). Multivariate analysis was performed to fit stroke volumes from gated myocardial perfusion imaging scans with linear and quadratic terms for dZ/dt(max) and the Fast Fourier Transform to identify significant parameters for incorporation into a cardiac arrest diagnostic algorithm. The square of the peak amplitude of the Fast Fourier Transform of dZ/dt was the best predictor of reduction in stroke volumes from gated myocardial perfusion imaging scans (range = 33-85 mL; p = .016). Having established that the two pad impedance cardiogram system could detect differences in stroke volumes from gated myocardial perfusion imaging scans, we assessed its performance in diagnosing cardiac arrest. Phase 2: The impedance cardiogram was recorded in 132 "cardiac arrest" patients (53 training, 79 validation) and 97 controls (47 training, 50 validation): the diagnostic algorithm indicated cardiac arrest with sensitivities and specificities (+/- exact 95% confidence intervals) of 89.1% (85.4-92.1) and 99.6% (99.4-99.7; training) and 81.1% (77.6-84.3) and 97% (96.7-97.4; validation).

CONCLUSIONS: The impedance cardiogram algorithm is a significant marker of circulatory collapse. Automated defibrillators with an integrated impedance cardiogram could improve emergency care by lay persons, enabling rapid and appropriate initiation of external cardiac massage.