Physiologically Relevant Levels of Biliverdin Do Not Significantly Oppose Oxidative Damage in Plasma In Vitro

AbstractAntioxidants have important physiological roles in limiting the amount of oxidative damage that an organism experiences. One putative antioxidant is biliverdin, a pigment that is most commonly associated with the blue or green colors of avian eggshells. However, despite claims that biliverdin functions as an antioxidant, neither the typical physiological concentrations of biliverdin in most species nor the ability of biliverdin to oppose oxidative damage at these concentrations has been examined. Therefore, we quantified biliverdin in the plasma of six bird species and found that they circulated levels of biliverdin between 0.02 and 0.5 μM. We then used a pool of plasma from northern bobwhite quail (Colinus virginianus) and spiked it with one of seven different concentrations of biliverdin, creating plasma-based solutions ranging from 0.09 to 231 μM biliverdin. We then compared each solution's ability to oppose oxidative damage in response to hydrogen peroxide relative to a control addition of water. We found that hydrogen peroxide consistently induced moderate amounts of oxidative damage (quantified as reactive oxygen metabolites) but that no concentration of biliverdin ameliorated this damage. However, biliverdin and hydrogen peroxide interacted, as the amount of biliverdin in hydrogen peroxide-treated samples was reduced to approximately zero, unless the initial concentration was over 100 μM biliverdin. These preliminary findings based on in vitro work indicate that while biliverdin may have important links to metabolism and immune function, at physiologically relevant concentrations it does not detectably oppose hydrogen peroxide-induced oxidative damage in plasma.

Blood chemistry and biliverdin differ according to reproduction and tourism in a free-living lizard

Changes in the physiological health of species are an essential indicator of changing conditions and environmental challenges. Reponses to environmental challenges can often induce stress, influence physiology, and change metabolism in organisms. Here we tested blood chemistry parameters indicative of stress and metabolic activity using an i-STAT point-of-care blood analyzer in seven populations of free-ranging rock iguanas exposed to varying levels of tourism and supplemental feeding. We found significant differences in blood chemistry (glucose, oxygen, carbon dioxide, hematocrit, hemoglobin, calcium, potassium, and biliverdin levels) among populations exposed to varying levels of tourism, and some variation between sexes and reproductive states. However, different variables are not directly related to one another, suggesting that the causal physiological pathways driving tourism-induced differences are influenced by mechanisms that are not detected by common analyses of blood chemistry. Future work should investigate upstream regulators of these factors affected by tourism. Regardless, these blood metrics are known to be both stress sensitive and related to metabolic activity, suggesting that exposure to tourism and associated supplemental feeding by tourists are generally driven by stress-related changes in blood chemistry, biliverdin, and metabolism.

Oxidative damage increases with degree of simulated bacterial infection, but not ectoparasitism, in tree swallow nestlings

The purpose of mounting an immune response is to destroy pathogens, but this response comes at a physiological cost, including the generation of oxidative damage. However, many studies on the effects of immune challenges employ a single high dose of a simulated infection, meaning that the consequences of more mild immune challenges are poorly understood. We tested whether the degree of immunological challenge in tree swallows (Tachycineta bicolor) affects oxidative physiology and body mass, and whether these metrics correlate with parasitic nest mite load. We injected 14 day old nestlings with 0, 0.01, 0.1 or 1 mg lipopolysaccharide (LPS) per kg body mass, then collected a blood sample 24 h later to quantify multiple physiological metrics, including oxidative damage (i.e. d-ROMs), circulating amounts of triglyceride and glycerol, and levels of the acute phase protein haptoglobin. After birds had fledged, we identified and counted parasitic nest mites (Dermanyssus spp. and Ornithonyssus spp.). We found that only nestlings injected with 1 mg LPS kg-1 body mass, which is a common dosage in ecoimmunological studies, lost more body mass than individuals from other treatment groups. However, every dose of LPS resulted in a commensurate increase in oxidative damage. Parasitic mite abundance had no effect on oxidative damage across treatments. The amount of oxidative damage correlated with haptoglobin levels, suggesting compensatory mechanisms to limit self-damage during an immune response. We conclude that while only the highest-intensity immune challenges resulted in costs related to body mass, even low-intensity immune challenges result in detectable increases in oxidative damage.

Correlates of bird collisions with buildings across three North American countries

Collisions with buildings cause up to 1 billion bird fatalities annually in the United States and Canada. However, efforts to reduce collisions would benefit from studies conducted at large spatial scales across multiple study sites with standardized methods and consideration of species- and life-history-related variation and correlates of collisions. We addressed these research needs through coordinated collection of data on bird collisions with buildings at sites in the United States (35), Canada (3), and Mexico (2). We collected all carcasses and identified species. After removing records for unidentified carcasses, species lacking distribution-wide population estimates, and species with distributions overlapping fewer than 10 sites, we retained 269 carcasses of 64 species for analysis. We estimated collision vulnerability for 40 bird species with ≥2 fatalities based on their North American population abundance, distribution overlap in study sites, and sampling effort. Of 10 species we identified as most vulnerable to collisions, some have been identified previously (e.g., Black-throated Blue Warbler [Setophaga caerulescens]), whereas others emerged for the first time (e.g., White-breasted Nuthatch [Sitta carolinensis]), possibly because we used a more standardized sampling approach than past studies. Building size and glass area were positively associated with number of collisions for 5 of 8 species with enough observations to analyze independently. Vegetation around buildings influenced collisions for only 1 of those 8 species (Swainson's Thrush [Catharus ustulatus]). Life history predicted collisions; numbers of collisions were greatest for migratory, insectivorous, and woodland-inhabiting species. Our results provide new insight into the species most vulnerable to building collisions, making them potentially in greatest need of conservation attention to reduce collisions and into species- and life-history-related variation and correlates of building collisions, information that can help refine collision management.

Low-dose immune challenges result in detectable levels of oxidative damage

Infection can result in substantial costs to animals, so they frequently respond by removing infectious agents with an immune response. However, immune responses entail their own costs, including upregulation of processes that destroy pathogens (e.g. the production of reactive oxygen species) and processes that limit the extent of self-damage during the immune response (e.g. production of anti-inflammatory proteins such as haptoglobin). Here, we simulated bacterial infection across a 1000-fold range using lipopolysaccharide (LPS) administered to northern bobwhite quail (Colinus virginianus), and quantified metrics related to pro-inflammatory conditions [i.e. generation of oxidative damage (d-ROMs), depletion of antioxidant capacity], anti-inflammatory mechanisms (i.e. production of haptoglobin, expression of the enzyme heme oxygenase, production of the organic molecule biliverdin) and nutritional physiology (e.g. circulating triglyceride levels, maintenance of body mass). We detected increases in levels of haptoglobin and d-ROMs even at LPS doses that are 1/1000th the concentration of doses frequently used in ecoimmunological studies, while loss of body mass and decreases in circulating triglycerides manifested only in individuals receiving the highest dose of LPS (1 mg LPS kg-1 body mass), highlighting variation among dose-dependent responses. Additionally, individuals that lost body mass during the course of the experiment had lower levels of circulating triglycerides, and those with more oxidative damage had greater levels of heme oxygenase expression, which highlights the complex interplay between pro- and anti-inflammatory processes. Because low doses of LPS may simulate natural infection levels, variation in dose-dependent physiological responses may be particularly important in modeling how free-living animals navigate immune challenges.

Exploring the barriers and facilitators for the use of digital health technologies for the management of COPD: a qualitative study of clinician perceptions

BACKGROUND

Digital health technology (DHT) promises to support patients and healthcare professionals (HCPs) to optimize the management of chronic obstructive pulmonary disease (COPD). However, there is a lack of evidence demonstrating the effectiveness of DHT for the management of COPD. One reason for this is the lack of user-involvement in the development of DHT interventions in COPD meaning their needs and preferences are rarely accounted for in the design phase. Although HCP adoption issues have been identified in relation to DHT, little is known about the challenges perceived by HCPs providing care to COPD patients. Therefore, this study aims to qualitatively explore the barriers and facilitators HCPs perceive for the use of DHT in the management of COPD.

METHODS

Participants (n = 32) were recruited using snowball sampling from two university hospitals and several general practitioner clinics. A semi-structured interview was conducted with each participant. NVivo 12 software was used to complete thematic analysis on the data.

RESULTS

Themes identified include: data quality; evidence-based care; resource constraints; and digital literacy presented as barriers; and facilitators include the following themes: digital health training and education; improving HCP digital literacy; and Personalized prescribing. Patient-centered approaches, such as pulmonary rehabilitation and shared decision-making were suggested as implementation strategies to ease the adoption of digital health for the management of COPD.

CONCLUSION

These findings contribute new insights about the needs and preferences of HCPs working in COPD regarding DHT. The findings can be used to help mitigate user-experience issues by informing the design of person-centered implementation and adoption strategies for future digital health interventions in COPD.

Immune challenge-induced oxidative damage may be mitigated by biliverdin

An effective immune response results in the elimination of pathogens, but this immunological benefit may be accompanied by increased levels of oxidative damage. However, organisms have evolved mechanisms to mitigate the extent of such oxidative damage, including the production and mobilization of antioxidants. One potential mechanism of mitigating immune challenge-induced changes in oxidative physiology is increasing biliverdin production. Biliverdin is chemically an antioxidant, but within-tissue correlations between biliverdin concentration and oxidative damage have never been directly examined. To test how biliverdin tissue concentrations are associated with physiological responses to an immune challenge, we exposed northern bobwhite quail (Colinus virginianus) to one of four treatments: injection of a non-pathogenic antigen - either lipopolysaccharide or phytohemagglutinin, control injection of phosphate-buffered saline or a sham procedure with no injection. Twenty-four hours later, we quantified oxidative damage and triglyceride concentration in the plasma, and biliverdin concentration in the plasma, liver and spleen. We found that both types of immune challenge increased oxidative damage relative to both non-injected and vehicle-injected controls, but treatment had no effects on any other metric. However, across all birds, oxidative damage and biliverdin concentration in the plasma were negatively correlated, which is consistent with a localized antioxidant function of biliverdin. Additionally, we uncovered multiple links between biliverdin concentration, change in mass during the immune challenges and triglyceride levels, suggesting that pathways associated with biliverdin production may also be associated with aspects of nutrient mobilization. Future experiments that manipulate biliverdin levels or oxidative damage directly could establish a systemic antioxidant function or elucidate important physiological impacts on body mass maintenance and triglyceride storage, mobilization or transport.

Plasticity of immunity in response to eating

Following a meal, an animal can exhibit dramatic shifts in physiology and morphology, as well as a substantial increase in metabolic rate associated with the energetic costs of processing a meal (i.e. specific dynamic action, SDA). However, little is known about the effects of digestion on another important physiological and energetically costly trait: immune function. Thus, we tested two competing hypotheses. (1) Digesting animals up-regulate their immune systems (putatively in response to the increased microbial exposure associated with ingested food). (2) Digesting animals down-regulate their immune systems (presumably to allocate energy to the breakdown of food). We assayed innate immunity (lytic capacity and agglutination) in cornsnakes (Pantherophis guttatus) during and after meal digestion. Lytic capacity was higher in females, and (in support of our first hypothesis) agglutination was higher during absorption. Given its potential energetic cost, immune up-regulation may contribute to SDA.

Eating increases oxidative damage in a reptile

While eating has substantial benefits in terms of both nutrient and energy acquisition, there are physiological costs associated with digesting and metabolizing a meal. Frequently, these costs have been documented in the context of energy expenditure while other physiological costs have been relatively unexplored. Here, we tested whether the seemingly innocuous act of eating affects either systemic pro-oxidant (reactive oxygen metabolites: ROM) levels or antioxidant capacity of corn snakes (Pantherophis guttatus) by collecting plasma during absorptive (peak increase in metabolic rate due to digestion of a meal) and non-absorptive (baseline) states. When individuals were digesting a meal, there was a minimal increase in antioxidant capacity relative to baseline (4%), but a substantial increase in ROMs (nearly 155%), even when controlling for circulating nutrient levels. We report an oxidative cost of eating that is much greater than that due to long distance flight or mounting an immune response in other taxa. This result demonstrates the importance of investigating non-energetic costs associated with meal processing, and it begs future work to identify the mechanism(s) driving this increase in ROM levels. Because energetic costs associated with eating are taxonomically widespread, identifying the taxonomic breadth of eating-induced ROM increases may provide insights into the interplay between oxidative damage and life history theory.

Assessing potential risks of treatment with long-term azithromycin in COPD patients: long-term oxygen users beware?

INTRODUCTION

Long-term daily azithromycin therapy reduces the frequency of exacerbations in chronic obstructive pulmonary disease (COPD) in a randomized controlled clinical trial setting. Concerns exist regarding arrhythmic and auditory toxicities from chronic use in the real-world setting. We hypothesized that risk factors for adverse drug reactions to azithromycin would be more frequent than previously reported, that certain specific subgroups would have different frequencies of these risk factors and that the whispered voice test would be a useful test with which to test for hearing deficits.

METHODS

Following ethical approval, 47 consecutive hospital-based patients with a mean age 69 years ± 8.2, and with physician-diagnosed COPD (mean FEV₁ 45.1 ± 18 % predicted), were screened for subjective hearing impairment (screening questions and whispered voice test) and by electrocardiogram for prolonged QTc. Other potential risk factors and contraindications to long-term daily azithromycin were sought.

RESULTS

In total, 38 patients (80.9 %) had at least one risk factor or contraindication to azithromycin treatment. 19 patients (40.4 % of total) had subjective hearing impairment. 17 (36.1 %) had prolonged QTc intervals. 4 patients (8.51 %) had contraindicating co-morbidities. Those on long-term oxygen therapy were significantly more likely to have at least one risk factors or contraindications to azithromycin (p = 0.0025).

CONCLUSION

In a COPD population who would otherwise potentially be candidates for long-term daily azithromycin therapy, over 80 % had risk factors for complications from long-term daily azithromycin. Preventative treatment with long-term daily azithromycin may be appropriate for fewer COPD patients than previously thought, especially in those on long-term oxygen therapy.

Ancient origins and multiple appearances of carotenoid-pigmented feathers in birds

The broad palette of feather colours displayed by birds serves diverse biological functions, including communication and camouflage. Fossil feathers provide evidence that some avian colours, like black and brown melanins, have existed for at least 160 million years (Myr), but no traces of bright carotenoid pigments in ancient feathers have been reported. Insight into the evolutionary history of plumage carotenoids may instead be gained from living species. We visually surveyed modern birds for carotenoid-consistent plumage colours (present in 2956 of 9993 species). We then used high-performance liquid chromatography and Raman spectroscopy to chemically assess the family-level distribution of plumage carotenoids, confirming their presence in 95 of 236 extant bird families (only 36 family-level occurrences had been confirmed previously). Using our data for all modern birds, we modelled the evolutionary history of carotenoid-consistent plumage colours on recent supertrees. Results support multiple independent origins of carotenoid plumage pigmentation in 13 orders, including six orders without previous reports of plumage carotenoids. Based on time calibrations from the supertree, the number of avian families displaying plumage carotenoids increased throughout the Cenozoic, and most plumage carotenoid originations occurred after the Miocene Epoch (23 Myr). The earliest origination of plumage carotenoids was reconstructed within Passeriformes, during the Palaeocene Epoch (66-56 Myr), and not at the base of crown-lineage birds.

The effect of carotenoid supplementation on immune system development in juvenile male veiled chameleons (Chamaeleo calyptratus)

Introduction

Nutrient availability, assimilation, and allocation can have important and lasting effects on the immune system development of growing animals. Though carotenoid pigments have immunostimulatory properties in many animals, relatively little is known regarding how they influence the immune system during development. Moreover, studies linking carotenoids to health at any life stage have largely been restricted to birds and mammals. We investigated the effects of carotenoid supplementation on multiple aspects of immunity in juvenile veiled chameleons (Chamaeleo calyptratus). We supplemented half of the chameleons with lutein (a xanthophyll carotenoid) for 14 weeks during development and serially measured multiple aspects of immune function, including: agglutination and lysis performance of plasma, wound healing, and plasma nitric oxide concentrations before and after wounding.

Results

Though lutein supplementation effectively elevated circulating carotenoid concentrations throughout the developmental period, we found no evidence that carotenoid repletion enhanced immune function at any point. However, agglutination and lysis scores increased, while baseline nitric oxide levels decreased, as chameleons aged.

Conclusions

Taken together, our results indicate that body mass and age, but not carotenoid access, may play an important role in immune performance of growing chameleons. Hence, studying well-understood physiological processes in novel taxa can provide new perspectives on alternative physiological processes and nutrient function.

Carotenoid supplementation during adulthood, but not development, decreases testis size in mallards

Nutritional constraints on reproduction are well-characterized in female animals, but rarely have particular nutrients been linked to male reproductive investments. Carotenoid pigments promote egg-laying and fertility in several animals, and are displayed externally within secondary sex traits by males of many colorful species to attract mates, but it is unclear if or how carotenoids affect male primary sex traits. We manipulated carotenoid availability in the diet of male mallards (Anas platyrhynchos) during both development and adulthood to determine effects on size and carotenoid content of the testes. We found that developmental carotenoid manipulations did not affect testis size or carotenoid concentration, but that increased carotenoid dietary levels at adulthood resulted in more carotenoid-rich, but smaller, testes. This latter result was surprising, given positive correlations in mammals between testicle size and carotenoid concentration. We also found negative correlations between testis size and carotenoid concentration for individual ducks, regardless of dietary treatment. These results suggest that carotenoid deposition into testis tissue can reduce investment in gonad size (and thus overall sperm count), although the functional consequences of this relationship remain to be tested.

Effects of carotenoid and vitamin E supplementation on oxidative stress and plumage coloration in house finches (Haemorhous mexicanus)

There has been much recent interest from both applied and basic scientists in the broad series of benefits that animals reap from acquiring high concentrations of dietary antioxidants, such as carotenoids and vitamins (e.g., vitamin E, or tocopherol). Most attention has been paid to separate effects of these compounds on, for example, coloration, health state, development, and vision, but because of possible interactions between these lipid-soluble molecules, we are in need of more studies that co-manipulate these substances and examine their possible synergistic impacts on animal physiology and phenotype. We capitalized on a model avian system (the house finch, Haemorhous mexicanus), where extensive information is available on the fitness roles of carotenoids, to test how variation in carotenoid and/or vitamin E concentrations in the diet impacts body accumulation of these compounds, factors related to oxidative damage (e.g., breast muscle and plasma oxidative-stress susceptibility, plasma nitric-oxide levels), and plumage color development. As in a previous study of ours on carotenoids and health in finches, we employed a 2×2 factorial experimental design on birds in both molting and non-molting conditions, to understand how seasonal shifts in carotenoid use (i.e., pigment incorporation into plumage) might alter the accumulation and roles of carotenoids and vitamins. As expected, lutein supplementation increased the level of circulating carotenoids in both experiments and the color of newly molted plumage. By contrast, vitamin E provisioning did not significantly affect plasma carotenoid levels or plumage coloration in either experiment. Interestingly, carotenoid provisioning decreased circulating vitamin E levels during molt, which suggests either molecular competition between carotenoids and tocopherol at the absorption/transport stages or that vitamin E serves as an antioxidant to offset harmful actions that carotenoids may have at very high concentrations. Finally, in both experiments, we found a reduction in breast-muscle oxidative damage for tocopherol-supplemented birds, which constitutes the first demonstration of a protective effect of vitamin E against oxidative stress in wild birds. Taken together, these findings provide an interesting contrast with our earlier work on season-specific physiological benefits of carotenoids in finches and point to complex associations between indicators of antioxidant and oxidative state in wild-caught animals.

The effect of hydration state and energy balance on innate immunity of a desert reptile

Introduction

Immune function is a vital physiological process that is often suppressed during times of resource scarcity due to investments in other physiological systems. While energy is the typical currency that has been examined in such trade-offs, limitations of other resources may similarly lead to trade-offs that affect immune function. Specifically, water is a critical resource with profound implications for organismal ecology, yet its availability can fluctuate at local, regional, and even global levels. Despite this, the effect of osmotic state on immune function has received little attention.

Results

Using agglutination and lysis assays as measures of an organism’s plasma concentration of natural antibodies and capacity for foreign cell destruction, respectively, we tested the independent effects of osmotic state, digestive state, and energy balance on innate immune function in free-ranging and laboratory populations of the Gila monster, Heloderma suspectum. This desert-dwelling lizard experiences dehydration and energy resource fluctuations on a seasonal basis. Dehydration was expected to decrease innate immune function, yet we found that dehydration increased lysis and agglutination abilities in both lab and field studies, a relationship that was not simply an effect of an increased concentration of immune molecules. Laboratory-based differences in digestive state were not associated with lysis or agglutination metrics, although in our field population, a loss of fat stores was correlated with an increase in lysis.

Conclusions

Depending on the life history of an organism, osmotic state may have a greater influence on immune function than energy availability. Thus, consideration of osmotic state as a factor influencing immune function will likely improve our understanding of ecoimmunology and the disease dynamics of a wide range of species.

Immune function is related to adult carotenoid and bile pigment levels, but not dietary carotenoid access during development, in female mallard ducks

Immune function can be modulated by multiple physiological factors, including nutrition and reproductive state. Because these factors can vary throughout an individual’s lifetime due to environmental conditions (e.g. nutrition) or life-history stage (e.g. adult reproduction), we must carefully examine the degree to which developmental versus adult conditions shape performance of the immune system. We investigated how variation in dietary access to carotenoid pigments – a class of molecules with immunostimulatory properties that females deposit into egg yolks – during three different developmental time points affected adult immunological and reproductive traits in female mallard ducks (Anas platyrhynchos). In males and females of other avian species, carotenoid access during development affects carotenoid assimilation ability, adult sexual ornamentation, and immune function, while carotenoid access at adulthood can increase immune response and reproductive investment (e.g. egg-laying capacity, biliverdin deposition in eggshells). We failed to find effects of developmental carotenoid supplementation on adult immune function (phytohemagglutinin-induced cutaneous immune response, antibody production in response to the novel antigen keyhole limpet hemocyanin [KLH], or oxidative burst, assessed by change in circulating nitric oxide levels), carotenoid-pigmented beak coloration, ovarian development, circulating carotenoid levels, or concentration of bile pigments in the gall bladder. However, we did uncover positive relationships between circulating carotenoid levels at adulthood and KLH-specific antibody production, and a negative relationship between biliverdin concentration in bile and KLH-specific antibody production. These results are consistent with the view that adult physiological parameters better predict current immune function than do developmental conditions and highlight a possible, previously unstudied relationship between biliverdin and immune system performance.

Differential effects of early- and late-life access to carotenoids on adult immune function and ornamentation in mallard ducks (Anas platyrhynchos)

Environmental conditions early in life can affect an organism’s phenotype at adulthood, which may be tuned to perform optimally in conditions that mimic those experienced during development (Environmental Matching hypothesis), or may be generally superior when conditions during development were of higher quality (Silver Spoon hypothesis). Here, we tested these hypotheses by examining how diet during development interacted with diet during adulthood to affect adult sexually selected ornamentation and immune function in male mallard ducks (Anas platyrhynchos). Mallards have yellow, carotenoid-pigmented beaks that are used in mate choice, and the degree of beak coloration has been linked to adult immune function. Using a 2×2 factorial experimental design, we reared mallards on diets containing either low or high levels of carotenoids (nutrients that cannot be synthesized de novo) throughout the period of growth, and then provided adults with one of these two diets while simultaneously quantifying beak coloration and response to a variety of immune challenges. We found that both developmental and adult carotenoid supplementation increased circulating carotenoid levels during dietary treatment, but that birds that received low-carotenoid diets during development maintained relatively higher circulating carotenoid levels during an adult immune challenge. Individuals that received low levels of carotenoids during development had larger phytohemagglutinin (PHA)-induced cutaneous immune responses at adulthood; however, dietary treatment during development and adulthood did not affect antibody response to a novel antigen, nitric oxide production, natural antibody levels, hemolytic capacity of the plasma, or beak coloration. However, beak coloration prior to immune challenges positively predicted PHA response, and strong PHA responses were correlated with losses in carotenoid-pigmented coloration. In sum, we did not find consistent support for either the Environmental Matching or Silver Spoon hypotheses. We then describe a new hypothesis that should be tested in future studies examining developmental plasticity.

Ontogenetic immune challenges shape adult personality in mallard ducks

Consistent individual differences in behaviour are widespread in animals, but the proximate mechanisms driving these differences remain largely unresolved. Parasitism and immune challenges are hypothesized to shape the expression of animal personality traits, but few studies have examined the influence of neonatal immune status on the development of adult personality. We examined how non-pathogenic immune challenges, administered at different stages of development, affected two common measures of personality, activity and exploratory behaviour, as well as colour-dependent novel object exploration in adult male mallard ducks (Anas platyrhynchos). We found that individuals that were immune-challenged during the middle (immediately following the completion of somatic growth) and late (during the acquisition of nuptial plumage) stages of development were more active in novel environments as adults relative to developmentally unchallenged birds or those challenged at an earlier developmental time point. Additionally, individuals challenged during the middle stage of development preferred orange and avoided red objects more than those that were not immune-challenged during development. Our results demonstrate that, in accordance with our predictions, early-life immune system perturbations alter the expression of personality traits later in life, emphasizing the role that developmental plasticity plays in shaping adult personality, and lending support to recent theoretical models that suggest that parasite pressure may play an important role in animal personality development.

Food color preferences against a dark, textured background vary in relation to sex and age in house finches (Carpodacus mexicanus)

Abstract

Many animals consume colorful foods, because bright coloration either enhances conspicuousness of food items or signals nutritional rewards. A comparatively under-studied aspect of food color preferences is the role of the background environment in shaping food detectability and choices. Previous work with house finches ( Carpodacus mexicanus), for example, showed that individuals preferred red and green food items and avoided yellow ones. However, this study of desert, ground-feeding birds was done with seeds presented against an artificial white background that is unlikely to reflect natural conditions. Therefore, we performed a similar experiment, but quantified selection of colorful foods using a different visual environment that better mimicked natural conditions. We mixed dark, inedible distractor pellets (i.e., analogous to natural desert sand and rocks) with sunflower kernels that were colored red, green, yellow, or orange to test for differences in foraging patterns by sex, age, and expression of male plumage coloration in non-molting house finches. This food presentation resulted in yellow seeds having a significantly greater chromatic, but not achromatic, contrast with the background than red or green seeds. Under these conditions, all birds consumed yellow, and to a lesser extent red, seeds most often, and both adult males and females had a strong preference for yellow kernels; adult males also tended to prefer green kernels, but females tended not to prefer green kernels. Juveniles showed no significant preferences for any seed color, and adult male plumage coloration was not related to seed color preference. Therefore, in contrast to studies using different foraging environments, house finches tended to prefer yellow seeds, supporting models that suggest that visual background and contrast may be more important than color per se in visually mediated foraging decisions of birds. Moreover, the fact that adult males and females differed in food color preference has not been reported previously in songbirds.

Glutathione S-transferase copy number variation alters lung gene expression

The glutathione S-transferase (GST) enzymes catalyse the conjugation of xenobiotics to glutathione. Based on reports that inherited copy number variations (CNVs) modulate some GST gene expression levels, and that the small airway epithelium (SAE) and alveolar macrophages (AMs) are involved early in the pathogenesis of smoking-induced lung disease, we asked: do germline CNVs modulate GST expression levels in SAE and AMs? Microarrays were used to survey GST gene expression and determine CNVs genotypes in SAE and AMs obtained by bronchoscopy from current smokers and nonsmokers. 26% of subjects were null for both GSTM1 alleles, with reduced GSTM1 mRNA levels seen in both SAE and AMs. 30% of subjects had homozygous deletions of GSTT1, with reduced mRNA levels in both tissues. Interestingly, GSTT2B exhibited homozygous deletion in the blood of 27% of subjects and was not expressed in SAE in the remainder of subjects, but was expressed in AMs of heterozygotes and wild-type subjects, proportionate to genotype. These data show a germline CNV-mediated linear relationship of genotype with expression level, suggesting minimal compensation of gene expression levels in heterozygotes, consistent with GST polymorphisms playing a role in the risk of smoking-associated, xenobiotic-induced lung disease.

Past or present? Relative contributions of developmental and adult conditions to adult immune function and coloration in mallard ducks (Anas platyrhynchos)

Developmental conditions affect adult physiological processes and phenotypic traits, including those associated with both survival and reproduction. Carotenoids are molecules that generate sexually attractive coloration, and these pigments are acquired throughout life and can affect antioxidant capacity and immunocompetence of young and old animals. However, few studies have tracked carotenoid status and condition during development and into adulthood to understand how ontogeny affects later-life health and coloration of both males and females. We reared male and female mallard ducks (Anas platyrhynchos) from hatch to adulthood, measured circulating carotenoid titers and body condition (i.e., size-adjusted body mass) throughout development, and assessed adult immune function and integumentary carotenoid-based beak and foot coloration. We found that adult immune function (wing web swelling response to phytohemagglutinin; PHA) in males was positively correlated with body condition during the growth period of development, rather than adult condition, and similarly that both male and female beak coloration was associated with developmental, rather than adult, body condition. We also found associations between coloration and health during adulthood; males with more carotenoid-rich beaks (a sexually attractive feature) tended to have a more robust adult PHA response and a greater antibody response to a novel antigen, while females with less carotenoid-rich beaks had greater antibody responsiveness at adulthood. In addition, male beak color changed over the course of the 24-h PHA test in proportion to the degree of PHA swelling. However, intensity of foot coloration (a trait of unknown sexual significance) was not associated with any condition, carotenoid, or immune metric for males or females. Taken together, our findings implicate key developmental components to the expression of both survival- and reproduction-related traits at adulthood, but that for a dynamic trait like beak color, there are also important adult conditions that can alter signal expression.

Immune-system activation depletes retinal carotenoids in house finches (Carpodacus mexicanus)

The costs of developing, maintaining, and activating the immune system have been cited as an important force shaping life-history evolution in animals. Immunological defenses require energy, nutrients and time that might otherwise be devoted to other life-history traits like sexual displays or reproduction. Carotenoid pigments in animals provide a unique opportunity to track the costs of immune activation, because they are diet-derived, modulate the immune system, and are used to develop colorful signals of quality. Carotenoids also accumulate in the retinas of birds, where they tune spectral sensitivity and provide photoprotection. If carotenoid accumulation in the retina follows the patterns of other tissues, then immune activation may deplete retinal carotenoid levels and impact visual health and function. To test this hypothesis, we challenged molting wild-caught captive house finches (Carpodacus mexicanus) with weekly injections of lipopolysaccharide (LPS) and phytohaemagglutinin (PHA) over the course of 8 weeks. Immunostimulated adult males and females produced significant antibody responses and molted more slowly than uninjected control birds. After 8 weeks, immune-challenged birds had significantly lower levels of specific retinal carotenoid types (galloxanthin and zeaxanthin), but there were no significant differences in the plasma, liver or feather carotenoid levels between the treatment groups. These results indicate that immune-system activation can specifically deplete retinal carotenoids, which may compromise visual health and performance and represent an additional somatic and behavioral cost of immunity.

Effects of small increases in corticosterone levels on morphology, immune function, and feather development

Stressors encountered during avian development may affect an individual's phenotype, including immunocompetence, growth, and feather quality. We examined effects of simulated chronic low-level stress on American kestrel (Falco sparverius) nestlings. Continuous release of corticosterone, a hormone involved in the stress response, can model chronic stress in birds. We implanted 13-d-old males with either corticosterone-filled implants or shams and measured their growth, immune function, and feather coloration. We found no significant differences between groups at the end of the weeklong exposure period in morphometrics (mass, tarsus, wing length, and asymmetry), immunocompetence (cutaneous immunity, heterophil/lymphocyte ratio, and humoral immunity), or feather coloration. One week subsequent to implant removal, however, differences were detected. Sham-implanted birds had significantly longer wings and a reduced level of cutaneous immune function compared with those of birds given corticosterone-filled implants. Therefore, increases of only 2 ng/mL in basal corticosterone titer can have small but measurable effects on subsequent avian development.

Iridescence: views from many angles

Iridescent colours have been fascinating to humans throughout history; they are flashy, shimmering, dynamic, and examples surround us, from the commonly seen iridescent sheen of oily street puddles to the exotic, gaudy displays of birds-of-paradise featured in nature documentaries. Iridescent colours and the structures that produce them have unique properties in comparison with other types of colourants found in nature. Scientists from a variety of disciplines study the optics, development, heritability, chemical make-up, origin, evolution, functions and biomimetic technological applications of naturally occurring iridescent colours. For the first time, graduate students at Arizona State University brought together these scientists, along with educators and artists, at 'Iridescence: more than meets the eye', a conference to promote interdisciplinary communication and collaboration in the study of iridescent coloration from all of these perspectives. Here, we summarize the outcomes of this conference, introduce the papers that follow in this special journal issue and briefly review the current status of our understanding of iridescence.

Many variations on a few themes: a broader look at development of iridescent scales (and feathers)

Iridescent structures are some of the most visually stunning phenomena in biological organisms. Insects and birds have in common the display of such colours in their non-living investiture, the scales and bristles in insects and the feathers in birds. The biological mechanisms underlying the formation of these structures, at least in insects, appear quite conservative in that the same architect, the eukaryotic cell, can produce not only the iridescent structure but, with some tweaking of the genome, other structures as well, a fact that may be of particular interest to materials scientists and industrial parties seeking to biomimic these forms. Here, we review two examples, one on the cellular and the other on the subcellular level of this developmental flexibility in insects. We then go on to review what is known about iridescent feather development in birds. We suggest that, in view of the increasing evidence that genes and pathways are conserved among taxa, the work on insects may perhaps suggest perspectives or directions of potential use in the study of birds.

Team Objective Structured Bedside Assessment (TOSBA): a novel and feasible way of providing formative teaching and assessment

It can be challenging to teach and assess medical students successfully in the setting of a hospital ward using real patients. We describe a novel method of providing weekly formative clinical assessment and teaching to final year students on an acute medical ward: The Team Objective Structured Bedside Assessment (TOSBA). The TOSBA involves three groups of five students rotating through three ward-based stations (each station consists of an inpatient and facilitator). Each group spends 25 minutes at a bedside station where the facilitator asks consecutive students to perform one of five clinical tasks. Every student receives a standardised grade and is provided with educational feedback at each of the three stations. We report our 15-month experience using the TOSBA format to assess and teach a large number of medical students on a weekly basis. We discuss the advantages and potential drawbacks of our approach.

Dissatisfaction with Do Not Attempt Resuscitation Orders: A nationwide study of Irish consultant physician practices

The legal/ethical status of Do Not Attempt Resuscitation (DNAR) orders in Ireland has not been clarified, nor have national policies been formulated. We questioned 298 consultant physicians in the Republic of Ireland about DNAR orders. 173 replies were received (58%). 85 expressed unsatisfactory understanding of issues relating to Irish DNAR orders (49%). 116 physicians felt that alert patients preferred not to discuss their own resuscitation (67%). 55 physicians felt that if a competent adult patient is the subject of a DNAR order without the patient's knowledge, the reasons for this decision are "almost never" documented in the patient's medical record (32%). 75 consultants "almost never" had advance discussion of resuscitation preferences with the patient (43%). 47 physicians had experienced advance directives for Irish patients (27%). 102 physicians felt that both they and the patient's next of kin had joint responsibility for deciding resuscitation status for an incapacitated patient with no advance directive (59%). 37 respondents described a formal resuscitation policy in their place of work (21%). We feel that physicians require greater national guidance regarding DNAR order-making, and we advocate more widespread use of resuscitation policies.

Managing exacerbations of COPD: room for improvement

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are a major cause of hospital admissions. Because of the consequent morbidity, mortality and burden on hospital resources, COPD management guidelines have been formulated. We reviewed 62 consecutive patients with AECOPD admitted from September 1st to December 18th 2000 in St. Vincents University Hospital, Ireland, including 3 months follow-up data, to evaluate the quality of care and in particular to assess the care of such patients by respiratory and non-respiratory physicians. There was a frequent failure to objectively confirm the diagnosis of COPD by spirometry (completed in 39 of the 51 patients who, at admission, had been previously labelled with COPD (76%), and in 53 out of 62 patients (85%) at the end of the study period), or to estimate severity by quantifying the FEV1 as a percentage of the normal predicted range (estimated in only 21 of the 39 patients who had spirometry previously performed (53%)). Those patients managed with input from respiratory physicians were more likely to have their diagnosis of COPD confirmed with spirometry (p < 0.05). They were also more likely to have out-patient follow-up arranged at discharge (p < 0.05). There was a trend towards the more frequent prescribing of oxygen to hypoxic patients in "respiratory" than in "non-respiratory" managed cases (p = 0.182) and a shorter hospital stay (0.1 < p < 0.5). 4 out of 11 severely hypoxaemic patients at admission (PO2 < 7.3kPa) were not screened at discharge for possible long term oxygen therapy (36%). 20 patients received combination antibiotic therapy with no infiltrate on CXR (32%). Pulmonary rehabilitation was offered to 12 patients (19%). 5 out of 18 current smokers had documented smoking cessation advice (28%) and none received smoking cessation pharmacotherapy. Finally we noted that the Hospital In-Patient Enquiry (HIPE) data and casualty department admission books were frequently misleading or medical records unlocatable (in 30 out of 92 cases (33%)). We conclude that the management of AECOPD at St. Vincent's University Hospital is frequently suboptimal, and may be managed better with respiratory physician involvement. In particular, there could be more frequent spirometric confirmation of the diagnosis of COPD, better screening for long term oxygen therapy and more conservative use of antibiotics. Audit is complicated by difficulty accessing relevant data.

Pulmonary cystic hydatid disease in Ireland

BACKGROUND

Hydatid disease is rare in Ireland and its incidence and prevalence are unknown. Most cases are diagnosed by a combination of clinical findings, morphological features on imaging and by serological testing.

AIMS

We describe an Irish case of pulmonary hydatid disease detected at bronchoscopy by bronchoalveolar lavage, and discuss the diagnosis and treatment of the disorder.

CONCLUSION

The diagnosis of this rare disease requires a high index of suspicion. Treatment is primarily surgical, with a role for antihelminthic agents.

Quinolone-associated tendonitis: a potential problem in COPD?

BACKGROUND

Quinolones have traditionally had limited application in the area of community-acquired respiratory tract infections due to poor cover against Streptococcus pneumoniae. This trend is changing with the broader spectrum of newer fluoroquinolones. A rare serious side effect of fluoroquinolones is tendinopathy.

AIMS

This study describes two cases of levofloxacin-associated tendinopathy in patients with severe chronic obstructive pulmonary disease (COPD) and the implications and mechanisms involved are discussed.

CONCLUSIONS

The finding of two cases of levofloxacin-induced tendinopathy in our patients suggests that the problem may be more frequent than previously considered. Patients with COPD treated with fluoroquinolones may have other risk factors for tendinopathy such as advanced age, corticosteroid use and renal impairment and merit vigilance for signs of tendonitis.

Differential effects of inhaled nitric oxide on normoxic and hypoxic isolated in situ neonatal pig lungs perfused by extracorporeal membrane oxygenation

Inhaled nitric oxide (NO) is effective as a selective pulmonary vasodilator, but its effects on uninjured lungs subjected to normoxia and hypoxia have not been fully studied. The authors sought the response of pulmonary vascular resistance (PVR) to inhaled NO in piglet lungs devoid of ischemic injury in a model of reversible pulmonary hypertension. If the changes were dose-responsive, the authors asked whether the PVR changes were related to normoxia or hypoxia, and hypothesized that the change would be more pronounced for hypoxia than normoxia. In situ isolated piglet lungs were prepared by occlusive tracheostomy and ligation of the ductus arteriosus and aorta. Cannulae positioned in the left atrium and pulmonary artery were connected to a standard extracorporeal membrane oxygenation (ECMO) circuit, and flow was increased to approximate cardiac output. After stabilization, piglets (aged 5 to 14 days, weighing 3.2 to 6.4 kg) were divided into two groups of four each: normoxic (FIO2 0.30, normal PVR) and hypoxic (FIO2 0.07, increased PVR). NO was administered at 10 to 80 parts per million (ppm) in increments of 10 ppm, for 5 minutes at each concentration, with a return to baseline before each new dose. Flow, pulmonary arterial (PA) and left atrial (LA) pressures were continuously monitored, from which PVR was calculated (PVR = [PPA - PLA]/flow) and expressed as log delta PVR. Data were analyzed statistically by repeated measures of analysis of variance, comparing log delta PVR to baseline at each dose of NO, and comparing log delta PVR for normoxic and hypoxic lungs at each dose of NO.(ABSTRACT TRUNCATED AT 250 WORDS)

Contemporary management of congenital diaphragmatic hernia

Despite advances in infant transport and intensive care, congenital diaphragmatic hernia (CDH) still poses a serious threat to life during the neonatal period. Only with the introduction of extracorporeal membrane oxygenation (ECMO) has mortality declined significantly. Understanding the pathophysiology of CDH and its devastating effect on the lungs' bronchial and vascular development assists the clinician in rational management during the perioperative period. Successful treatment demands prompt diagnosis, informed preoperative assessment and preparation, carefully timed surgical repair, and aggressive postoperative intensive care with a thorough understanding of the role of ECMO. Improvements in ventilatory support and pharmacologic management of pulmonary hypertension have allowed surgeons to delay repair until circulatory hemodynamics, electrolytes, and oxygenation can be optimized, even resorting to preoperative ECMO in selected cases if needed. Patients with severe bilateral pulmonary hypoplasia pose serious dilemmas in terms of selection for ECMO, as well as for surgical repair. Long-term follow-up of patients after CDH repair reveals persistent hypoperfusion of the involved lung but no debilitating pulmonary disease. Future therapies may include early fetal intervention or lung transplantation, although these areas remain controversial and experimental, and clinical experience is limited.