Differential ecological impacts of an invader and a native under environmental change are revealed by comparative functional responses.

Predicting the ecological impacts of damaging invasive species under relevant environmental contexts is a major challenge, for which comparative functional responses (the relationship between resource availability and consumer uptake rate) have great potential. Here, the functional responses of Gammarus pulex, an ecologically damaging invader in freshwaters in Ireland and other islands, were compared with those of a native trophic equivalent Gammarus duebeni celticus. Experiments were conducted at two dissolved oxygen concentrations (80 and 50 % saturation), representative of anthropogenic water quality changes, using two larval prey, blackfly (Simuliidae spp.) and mayfly (Baetis rhodani). Overall, G. pulex had higher Type II functional responses and hence predatory impacts than G. d. celticus and the functional responses of both predators were reduced by lowered oxygen concentration. However, this reduction was of lower magnitude for the invader as compared to the native. Further, the invader functional response at low oxygen was comparable to that of the native at high oxygen. Attack rates of the two predators were similar, with low oxygen reducing these attack rates, but this effect occurred more strongly for blackfly than mayfly prey. Handling times were significantly lower for the invader compared with the native, and significantly higher at low oxygen, however, the effect of lowered oxygen on handling times was minimal for the invader and pronounced for the native. Maximum feeding rates were significantly greater for the invader compared with the native, and significantly reduced at low oxygen, with this effect again lesser for the invader as compared to the native. The greater functional responses of the invader corroborate with its impacts on recipient macroinvertebrate communities when it replaces the native. Further, our experiments predict that the impact of the invader will be less affected than the native under altered oxygen regimes driven by anthropogenic influences.

Functional identity and diversity of animals predict ecosystem functioning better than species-based indices

Drastic biodiversity declines have raised concerns about the deterioration of ecosystem functions and have motivated much recent research on the relationship between species diversity and ecosystem functioning. A functional trait framework has been proposed to improve the mechanistic understanding of this relationship, but this has rarely been tested for organisms other than plants. We analysed eight datasets, including five animal groups, to examine how well a trait-based approach, compared with a more traditional taxonomic approach, predicts seven ecosystem functions below- and above-ground. Trait-based indices consistently provided greater explanatory power than species richness or abundance. The frequency distributions of single or multiple traits in the community were the best predictors of ecosystem functioning. This implies that the ecosystem functions we investigated were underpinned by the combination of trait identities (i.e. single-trait indices) and trait complementarity (i.e. multi-trait indices) in the communities. Our study provides new insights into the general mechanisms that link biodiversity to ecosystem functioning in natural animal communities and suggests that the observed responses were due to the identity and dominance patterns of the trait composition rather than the number or abundance of species per se.

On the context-dependent scaling of consumer feeding rates

The stability of consumer-resource systems can depend on the form of feeding interactions (i.e. functional responses). Size-based models predict interactions - and thus stability - based on consumer-resource size ratios. However, little is known about how interaction contexts (e.g. simple or complex habitats) might alter scaling relationships. Addressing this, we experimentally measured interactions between a large size range of aquatic predators (4-6400 mg over 1347 feeding trials) and an invasive prey that transitions among habitats: from the water column (3D interactions) to simple and complex benthic substrates (2D interactions). Simple and complex substrates mediated successive reductions in capture rates - particularly around the unimodal optimum - and promoted prey population stability in model simulations. Many real consumer-resource systems transition between 2D and 3D interactions, and along complexity gradients. Thus, Context-Dependent Scaling (CDS) of feeding interactions could represent an unrecognised aspect of food webs, and quantifying the extent of CDS might enhance predictive ecology.

Structural and Functional Lung Impairment in Adult Survivors of Bronchopulmonary Dysplasia

RATIONALE: As more preterm infants recover from severe bronchopulmonary dysplasia (BPD), it is critical to understand the clinical consequences of this condition on the lung health of adult survivors.

OBJECTIVES: To assess structural and functional lung parameters in young adult BPD survivors and preterm and term controls Methods: Young adult survivors of BPD (mean age 24) underwent spirometry, lung volumes, transfer factor, lung clearance index and fractional exhaled nitric oxide measurements together with high-resolution chest tomographic (CT) imaging and cardiopulmonary exercise testing.

MEASUREMENTS AND MAIN RESULTS: 25 adult BPD survivors, (mean ± SD gestational age 26.8 ± 2.3 weeks; birth weight 866 ± 255 g), 24 adult prematurely born non-BPD controls (gestational age 30.6 ± 1.9 weeks; birth weight 1234 ± 207 g) and 25 adult term birth control subjects (gestational age 38.5 ± 0.9 weeks; and birth weight 3569 ± 2979 g) were studied. BPD subjects were more likely to be wakened by cough (OR 9.7, 95% CI: 1.8 to 52.6), p<0.01), wheeze and breathlessness (OR 12.2, 95%CI: 1.3 to 112), p<0.05) than term controls after adjusting for sex and current smoking. Preterm subjects had greater airways obstruction than term subjects. BPD subjects had significantly lower values for FEV1 and FEF25-75 (% predicted and z scores) than term controls (both p<0.001). Although non-BPD subjects also had lower spirometric values than term controls, none of the differences reached statistical significance. More BPD subjects (25%) had fixed airflow obstruction than non-BPD (12.5%) and term (0%) subjects (p=0.004). Both BPD and non-BPD subjects had significantly greater impairment in gas transfer (KCO % predicted) than term subjects (both p<0.05). Eighteen (37%) preterm participants were classified as small for gestational age (birth weight < 10th percentile for gestational age). These subjects had significantly greater impairment in FEV1 (% predicted and z scores) than those born appropriate for gestational age. BPD survivors had significantly more severe radiographic structural lung impairment than non-BPD subjects. Both preterm groups had impaired exercise capacity compared to term controls. There was a trend for greater limitation and leg discomfort in BPD survivors.

CONCLUSIONS: Adult preterm birth survivors, especially those who developed BPD, continue to experience respiratory symptoms and exhibit clinically important levels of pulmonary impairment.

PROGNOSTIC FACTORS PREDICTING FUNCTIONAL OUTCOME AT FOUR MONTHS FOLLOWING ACUTE ANKLE SPRAIN

PROGNOSTIC FACTORS PREDICTING FUNCTIONAL OUTCOME AT FOUR MONTHS FOLLOWING ACUTE ANKLE SPRAINBleakley C.M.1, O'Connor S.R.1, Tully M.A.2, Rocke L.G.3, MacAuley D.C.1, Bradbury I.4, Keegan S.4, McDonough S.M.11University of Ulster, Health & Rehabilitation Sciences Research Institute, Newtownabbey, United Kingdom, 2Queen's University, UKCRC Centre of Excellence for Public Health (NI), Belfast, United Kingdom, 3Royal Victoria Hospital, Department of Emergency Medicine, Belfast, United Kingdom, 4Frontier Science (Scotland), Kincraig, Inverness-shire, United KingdomPurpose: To identify clinically relevant factors assessed following acute ankle sprain that predict functional recovery at four months post-injury.Relevance: Ankle sprains are one of the most common musculoskeletal injuries with an estimated 5000 new cases occurring each day in the United Kingdom. In the acute phase, ankle sprains may be associated with pain and loss of function. In the longer-term there is a risk of residual problems including chronic pain or reinjury. Few studies have sought to examine factors associated with a poor long-term prognosis.Participants: 101 patients (Age: Mean (SD) 25.9 (7.9) years; Body Mass Index (BMI): 25.3 (3.5) kg/m2) with an acute grade 1 or 2 ankle sprain attending an accident and emergency department or sports injury clinic. Exclusion criteria included complete (grade 3) rupture of the ankle ligament complex, bony ankle injury or multiple injuries.Methods: Participants were allocated as part of a randomised controlled trial to an accelerated intervention incorporating intermittent ice and early therapeutic exercise or a standard protection, rest, ice, compression, and elevation intervention for one week. Treatment was then standardised in both groups and consisted of ankle rehabilitation exercises focusing on muscle strengthening, neuromuscular training, and sports specific functional exercises for a period of approximately four to six weeks. On initial assessment age, gender, mechanism of injury, presence of an audible pop or snap and the presence of contact during the injury were recorded. The following factors were also recorded at baseline and at one and four weeks post-injury: weight-bearing dorsi-flexion test, lateral hop test, presence of medial pain on palpation and a positive impingement sign. Functional status was assessed using the Karlsson score at baseline, at week four and at four months. Reinjury rates were recorded throughout the intervention phase and at four months.Analysis: A mixed between-within subjects analysis of variance (ANOVA) was used to determine the effect of each factor on functional status at week four and at four months. Significance was set at a Bonferroni adjusted level of 0.0125 (0.05/4).Results: Eighty-five participants (84%) were available at final follow-up assessment. Pain on weight-bearing dorsi-flexion and lateral hop tests at week four were both associated with a lower functional score at four months post-injury (P = 0.011 and P = 0.001). No other significant interactions were observed at any other timepoint (baseline or week one). There were only two reinjuries within the four month follow-up period with a further two reported at approximately six months post-injury. We were therefore unable to determine whether any factors were associated with an increased risk of reinjury.Conclusions: Potential prognostic factors on initial or early examination after acute ankle sprain did not help predict functional recovery at four months post-injury. However, pain on weight-bearing dorsi-flexion and lateral hop tests observed at four weeks were associated with a slower rate of recovery.Implications: Some clinical tests may help identify patients at risk of poor functional recovery after acute ankle sprain. However, further work is required to examine factors which may be predictive on initial assessment.Key-words: 1. Prognostic factors 2. Recovery 3. Ankle sprainFunding acknowledgements: Physiotherapy Research Foundation, Chartered Society of Physiotherapy, Strategic Priority Fund; Department of Employment and Learning, Northern Ireland.Ethics approval: Office for Research Ethics Committee (UK).

Functional analysis of the ATM-p53-p21 pathway in the LRF CLL4 trial: blockade at the level of p21 is associated with short response duration.

PURPOSE: This study sought to establish whether functional analysis of the ATM-p53-p21 pathway adds to the information provided by currently available prognostic factors in patients with chronic lymphocytic leukemia (CLL) requiring frontline chemotherapy. EXPERIMENTAL DESIGN: Cryopreserved blood mononuclear cells from 278 patients entering the LRF CLL4 trial comparing chlorambucil, fludarabine, and fludarabine plus cyclophosphamide were analyzed for ATM-p53-p21 pathway defects using an ex vivo functional assay that uses ionizing radiation to activate ATM and flow cytometry to measure upregulation of p53 and p21 proteins. Clinical endpoints were compared between groups of patients defined by their pathway status. RESULTS: ATM-p53-p21 pathway defects of four different types (A, B, C, and D) were identified in 194 of 278 (70%) samples. The type A defect (high constitutive p53 expression combined with impaired p21 upregulation) and the type C defect (impaired p21 upregulation despite an intact p53 response) were each associated with short progression-free survival. The type A defect was associated with chemoresistance, whereas the type C defect was associated with early relapse. As expected, the type A defect was strongly associated with TP53 deletion/mutation. In contrast, the type C defect was not associated with any of the other prognostic factors examined, including TP53/ATM deletion, TP53 mutation, and IGHV mutational status. Detection of the type C defect added to the prognostic information provided by TP53/ATM deletion, TP53 mutation, and IGHV status. CONCLUSION: Our findings implicate blockade of the ATM-p53-p21 pathway at the level of p21 as a hitherto unrecognized determinant of early disease recurrence following successful cytoreduction.

Functional management of ankle sprains: what volume and intensity of walking is undertaken in the first week

BACKGROUND:
Acute ankle sprains are usually managed functionally, with advice to undertake progressive weight-bearing and walking. Mechanical loading is an important modular of tissue repair; therefore, the clinical effectiveness of walking after ankle sprain may be dose dependent. The intensity, magnitude and duration of load associated with current functional treatments for ankle sprain are unclear.
AIM:
To describe physical activity (PA) in the first week after ankle sprain and to compare results with a healthy control group.
METHODS:
Participants (16-65 years) with an acute ankle sprain were randomised into two groups (standard or exercise). Both groups were advised to apply ice and compression, and walk within the limits of pain. The exercise group undertook additional therapeutic exercises. PA was measured using an activPAL accelerometer, worn for 7 days after injury. Comparisons were made with a non-injured control group.
RESULTS:
The standard group were significantly less active (1.2 ± 0.4 h activity/day; 5621 ± 2294 steps/day) than the exercise (1.7 ± 0 .7 h/day, p=0.04; 7886 ± 3075 steps/day, p=0.03) and non-injured control groups (1.7 ± 0.4 h/day, p=0.02; 8844 ± 2185 steps/day, p=0.002). Also, compared with the non-injured control group, the standard and exercise groups spent less time in moderate (38.3 ± 12.7 min/day vs 14.5 ± 11.4 min/day, p=0.001 and 22.5 ± 15.9 min/day, p=0.003) and high-intensity activity (4.1 ± 6.9 min/day vs 0.1 ± 0.1 min/day, p=0.001 and 0.62 ± 1.0 min/day p=0.005).
CONCLUSION:
PA patterns are reduced in the first week after ankle sprain, which is partly ameliorated with addition of therapeutic exercises. This study represents the first step towards developing evidence-based walking prescription after acute ankle sprain.