Gross vs. net income: How plant toughness affects performance of an insect herbivore

Leaf biomechanical properties are thought to impose a significant obstacle to herbivores and as such influence patterns of herbivory more than leaf chemistry. However, evidence for the role of structural traits in influencing herbivore food choice and performance has come from correlative studies, whereas the underlying mechanisms have been given little attention. By manipulating the biomechanical properties of a host grass species through a combination of lyophilization and milling, and providing water separately, we were able to compare behavioral, physiological, and developmental responses of the Australian plague locust, Chortoicetes terminifera, to the biomechanical properties of plant food (exemplified by toughness) independently of the food's macronutrient content and the insect's demand for water. Increasing leaf toughness was associated with reduced rates of locust growth and prolonged development, with potential ecological consequences. Poorer performance on the tougher foods was primarily a consequence of a reduced rate of nutrient supply, which occurred as a result of (1) smaller meals being eaten more slowly, (2) slowed gut passage rates, which limited how quickly the next meal could be taken, and (3) reduced efficiency of assimilation of nutrients from food in the gut. In addition, there were deleterious changes in the ratio of protein to carbohydrate assimilated from the gut. Prolonged development time was associated with increased total nutrient demands throughout the extended developmental period. Because these demands could not be met by increased consumption, there was a decreased efficiency of conversion of assimilated nutrients to growth. By disentangling the effects of biomechanical properties from macronutrient and water content we have shown that leaf biomechanical traits can influence chewing herbivores independently of leaf chemical traits.

Disabled children in the UK: a quality assessment of quantitative data sources

BACKGROUND

The limitations of reliable and accessible UK national and local quantitative data on the prevalence of childhood disability and the characteristics and circumstances of disabled children and their households have been recognized for some time. This paper reports the findings from a study that scoped and quality-assessed existing quantitative UK national and regional data sets on disabled children and their families.

METHODS

A comprehensive search of relevant data sources with information on disabled children was undertaken. Data sources were evaluated with reference to: disability definitions and questions; potential to generate nationally representative prevalence estimates of disabled children; study design; population coverage; sampling issues; social and demographic data; appropriateness for identifying childhood as opposed to adult disability.

RESULTS

Thirty-seven data sources with information on childhood disability were identified, of which 30 met the inclusion criteria: nine cross-sectional surveys, nine longitudinal and panel studies, seven administrative data sets, four specific condition databases and one was another type. Definitions and questions varied across data sources. Long-standing illness and limiting long-standing illness were the most consistently used definitions. Repeated cross-sectional surveys were found to be most appropriate for estimating overall prevalence but, with the exception of the Population Census, sample sizes were too small to study prevalence and characteristics by some population sub-groups such, including age by year, minority ethnic status and socio-economic position. Few data sources included questions appropriate for identifying childhood as opposed to adult disability or collected information from disabled children themselves.

CONCLUSIONS

Our findings summarize the currently available quantitative data sources on childhood disability and highlight the limitations. We make recommendations for the future development of more robust childhood disability data and issues requiring further research. To assist policy makers and service providers to make use of current data sources we have produced a brief online guide based on our findings.

Lopinavir protein binding in HIV-1-infected pregnant women

BACKGROUND

Pregnancy may alter protein binding (PB) of highly bound protease inhibitors due to changes in plasma concentrations of albumin and alpha-1 acid glycoprotein (AAG). Small changes in PB can greatly impact the fraction of drug unbound (FU) exerting pharmacological effect. We report lopinavir (LPV) PB during third trimester (antepartum, AP) compared to > or =1.7 weeks postpartum (PP) to determine if FU changes compensate for reduced total concentrations reported previously.

METHODS

P1026s enrolled women receiving LPV/ritonavir, soft gel capsules 400/100 mg or 533/133 mg twice daily. LPV FU, albumin and AAG were determined AP and PP.

RESULTS

AP/PP samples were available from 29/25 women respectively with all but one woman receiving the same dose AP/PP. LPV FU was increased 18% AP vs. PP (mean 0.96+/-0.16% AP vs. 0.82+/-0.21% PP, P=0.001). Mean protein concentrations were reduced AP (AAG=477 mg/L; albumin=3.28 mg/dL) vs. PP (AAG=1007 mg/L; albumin=3.85 mg/dL) (P<0.0001 for each comparison). AAG concentration correlated with LPV binding. Total LPV concentration did not correlate with LPV FU AP or PP. However, higher LPV concentration PP was associated with reduced PB and higher FU after adjustment for AAG.

CONCLUSIONS

LPV FU was higher and AAG lower AP vs. PP. The 18% increase in LPV FU AP is smaller than the reduction in total LPV concentration reported previously and is not of sufficient magnitude to eliminate the need for an increased dose during pregnancy.

Vandetanib plus pemetrexed versus pemetrexed as second-line therapy in patients with advanced non-small cell lung cancer (NSCLC): A randomized, double-blind phase III trial (ZEAL)

8010

Background: Vandetanib is a once-daily oral inhibitor of VEGFR, EGFR and RET signaling. A phase I trial of vandetanib + pemetrexed (pem) supported further investigation of this combination (de Boer et al, Ann Oncol 2008). Methods: The primary objective was to determine whether vandetanib 100 mg/day + pem 500 mg/m2 every 21 days (max 6 cycles) prolonged progression-free survival (PFS) vs placebo + pem. Overall survival (OS), objective response rate (ORR), time to deterioration of symptoms (TDS, by Lung Cancer Symptom Scale) and safety were secondary endpoints. Efficacy and safety were assessed in females as a co-primary analysis population. Eligibility criteria included stage IIIB/IV NSCLC, PS 0–2, and previous 1st-line therapy. Results: Between Jan 07-Mar 08, 534 patients (mean age 59 yrs; 38% female; 21% squamous histology; 8% brain metastases; stage IV 84%; PS 0/1/2: 41%/53%/6%) were randomized 1:1 to receive vandetanib + pem (n=256) or placebo + pem (n=278). Baseline characteristics were similar in both arms. Median duration of follow-up was 9.0 months, with 83% patients progressed and 50% deceased. There were positive trends seen for vandetanib + pem for both PFS (hazard ratio [HR] 0.86, 97.58% CI 0.69–1.06; P=0.108) and OS (HR 0.86, 97.54% CI 0.65–1.13; P=0.219); similar advantages were observed for females. There were statistically significant advantages for ORR (19.1% vs 7.9%, P<0.001) and TDS (HR 0.61, P=0.004). The adverse event profile was consistent with previous studies of vandetanib: rash (38% vs 26%), diarrhea (26% vs 18%) and hypertension (12% vs 3%) being more frequent in the vandetanib arm. There was evidence of reduced pem toxicity with the addition of vandetanib: anemia 8% vs 22%, nausea 29% vs 37%, vomiting 15% vs 22%, fatigue 37% vs 45%, and asthenia 11% vs 17%. The incidence of protocol-defined QTc prolongation was <1%. There was no increase in bleeding or thrombotic events in the vandetanib arm. Conclusions: The combination of vandetanib + pem demonstrated evidence of clinical benefit in patients with pretreated advanced NSCLC, although the study did not meet the primary endpoint of statistically significant PFS prolongation vs pem alone. Vandetanib + pem was generally well tolerated.

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A framework for assessing regional biodiversity condition under changing environments of the arid Australian rangelands

Rangelands support many ecosystem services important to humans, including climate regulation. They also have a significant role to play in the mitigation of greenhouse gases. However, the capacity of any rangeland to do this depends foremost upon the condition of biodiversity, and the functioning of its ecosystems. Considerable research has been undertaken on rangeland condition but it has not yet included the assessment of biodiversity (plants, animals and microbes) as a primary focus. Rangeland managers have struggled to assess biodiversity condition because it is rarely defined, is everywhere (so what do you assess?), is always changing in response to natural and human disturbances (so how do you know when it has changed?) and what amount signals management action. Here we present a framework that addresses these issues, and apply it to select surrogates and indicators that are scientifically defensible in biological and planning terms for assessing biodiversity. An arid Australian rangeland region is used as a case study to develop and apply our approach. We were not able to illustrate interpretation of condition because of the absence of long-term monitoring data in Australian rangelands, but we do provide guiding principles about sampling design and analytical methods for interpretation that use raw data rather than multimetrics. We discovered that different management outcomes expected to be informed from assessing biodiversity condition affected surrogate and indicator choice, and that a number indicators were not robust when assessed on conceptual relevance, measurement qualities, feasibility of implementation and policy and management relevance for four different management outcomes. Our work highlights the importance of stating the expected outcomes of biodiversity condition assessments up front, so that indicators relevant to future management are chosen. It also shows that critical thought on the robustness of indicators is warranted, especially as condition assessments under climate change will require information on the functional traits of species. We conclude by assessing the strengths and weaknesses of our framework in relation to environmental planning.

Age-size plasticity for reproduction in monocarpic plants

Empirical and theoretical investigations of monocarpy have usually addressed the question of minimum or threshold sizes for reproduction. However, the range of flowering sizes observed in many monocarpic species is extraordinarily large (well beyond what can be called a "threshold"), and the sizes of flowering and nonflowering plants may overlap greatly. We attempt to explain these reproductive patterns in terms of optimal reaction norms predicted by simple deterministic life history models. We assume that individuals differ in their growth trajectories due to the heterogeneous quality of microsites and ask how the optimal age and size at flowering varies with environmental variation in growth and for different assumptions about fecundity and mortality. Under two very different growth functions (one with no age- or size-related decline in growth rate and another with such a decline as size approaches an asymptote), the optimal reaction norms imply considerable plasticity for size at reproduction, particularly when poor growth is associated with higher mortality or lower asymptotic size. Deterministic models such as these may be more applicable to long-lived than to short-lived monocarps, because fitness potential should be less affected by stochastic variability in yearly growing condition in the former than in the latter. We consider the case of a tropical monocarpic and masting tree species, Cerberiopsis candelabra (Apocynaceae), and show that our model results can account for wide ranges of reproductive size and overlap in size of flowering and nonflowering plants, in accord with observation. We suggest that empirical attention to norms of reaction across growth environments will be a more profitable approach than investigation of size thresholds per se.