Dominance-related seasonal song production is unrelated to circulating testosterone in a subtropical songbird

Circulating testosterone (T) is widely considered to play a key role in the production of sexual displays by male vertebrates. While numerous studies support a role for circulating T in promoting the production of song in male birds, this understanding is based primarily on evidence from seasonally breeding northern temperate species, leaving it unclear whether this mechanism generalizes to other regions of the world. Here we investigate whether variation in circulating levels of T can explain the marked within- and among-individual variation in male song performance observed in a subtropical population of the year-round territorial white-browed sparrow weaver (Plocepasser mahali mahali). Our findings reveal that both circulating T and male song production peaked at a similar time point, halfway through the population-level breeding season. However, while dominant males were more likely to sing and sang for longer than subordinate males, within-group paired comparisons revealed no dominance-related differences in circulating T. Moreover, comparisons both among and within individual dominant males revealed that song duration, syllable rate and proportion of time spent singing were all unrelated to circulating T. Together, our findings suggest that natural variation in male song production, at least in this population of white-browed sparrow weavers, is achieved principally through mechanisms other than variation in circulating T concentration. More widely, our results are in line with the view that male song production is not exclusively regulated by gonadally synthesized steroids.

BMI and Lower Extremity Injury in U.S. Army Soldiers, 2001-2011

INTRODUCTION

Little data exist regarding the long-term impact of excess weight on lower extremity musculoskeletal injury/disorder (MID) in U.S. Army Soldiers. This prospective analysis examines the association between BMI of Soldiers at accession and risk of MID.

METHODS

A total of 736,608 Soldiers were followed from accession into the Army, 2001-2011. Data were analyzed January through March 2015. MID was categorized as any first incident lower extremity musculoskeletal injury/disorder, and secondarily, as first incident injury/disorder at a specific site (i.e., hips, upper legs/thighs, knees, lower legs/ankles, feet/toes). Multivariable-adjusted proportional hazards models estimated associations between BMI category at accession and MID risk.

RESULTS

During 15,678,743 person-months of follow-up, 411,413 cases of any first MID were documented (70,578 hip, 77,050 upper leg, 162,041 knee, 338,080 lower leg, and 100,935 foot injuries in secondary analyses). The overall MID rate was 2.62 per 100 person-months. Relative to Soldiers with normal BMI (18.5 to <25 kg/m(2)) at accession, those who were underweight (<18.5); overweight (25 to <30); or obese (≥30) had 7%, 11%, and 33% higher risk of MID, respectively, after adjustment. Risks were highest in Soldiers who were obese at accession, and lowest in those with a BMI of 21-23 kg/m(2).

CONCLUSIONS

Soldier BMI at accession has important implications for MID. A BMI of 21-23 kg/m(2) in newly accessing Soldiers was associated with the lowest risk of incident MID, suggesting that accession be limited to people within this range to reduce overall incidence of MID among service personnel.

The distribution of the dwarf succulent genus Conophytum N.E.Br. (Aizoaceae) in southern Africa

Background: The dwarf succulent genus Conophytum N.E.Br. is one of the most species rich in the Aizoceae. The genus is most closely associated with a region of high floral endemism and biodiversity, the Succulent Karoo biome in south-western Africa.Objectives: To examine the distribution of Conophytum in south-western Namibia and in the Northern and Western Cape Provinces of South Africa.Method: A database comprising 2798 locality records representing all known species and subspecies of the genus Conophytum has been constructed.Results: The genus is primarily restricted to the arid winter-rainfall region of the Northern and Western Cape Provinces of South Africa and south-western Namibia, within the Greater Cape Floristic Region. Whilst taxa are found across all the main biomes in the region (the Succulent Karoo, Nama Karoo, Desert and Fynbos biomes), 94% of Conophytum taxa are found only in the Succulent Karoo biome and predominantly (88% of taxa) within South Africa. Endemism within specific bioregions is a feature of the genus and ~60% of taxa are endemic to the Succulent Karoo. Approximately 28% of all taxa could be considered point endemics. Whilst the genus has a relatively wide geographical range, we identify a pronounced centre of endemism in the southern Richtersveld.Conclusion: The genus Conophytum can be used as a good botanical model for studying patterns of diversity and speciation in the Succulent Karoo biome, the effects of climate change on dwarf succulents, and for informing conservation planning efforts.

Fundamental problems with the cooperative breeding hypothesis. A reply to Burkart & van Schaik

The cooperative breeding hypothesis (CBH) states that cooperative breeding, a social system in which group members help to rear offspring that are not their own, has important socio‐cognitive consequences. Thornton & McAuliffe (2015; henceforth T&M) critiqued this idea on both conceptual and empirical grounds, arguing that there is no reason to predict that cooperative breeding should favour the evolution of enhanced social cognition or larger brains, nor any clear evidence that it does. In response to this critique, Burkart & van Schaik (2016 henceforth B&vS) attempt to clarify the causal logic of the CBH, revisit the data and raise the possibility that the hypothesis may only apply to primates. They concede that cooperative breeding is unlikely to generate selection pressures for enhanced socio‐cognitive abilities, but argue instead that the CBH operates purely through cooperative breeding reducing social or energetic constraints. Here, we argue that this revised hypothesis is also untenable because: (1) it cannot explain why resources so released would be allocated to cognitive traits per se rather than any other fitness‐related traits, (2) key assumptions are inconsistent with available evidence and (3) ambiguity regarding the predictions leaves it unclear what evidence would be required to falsify it. Ultimately, the absence of any compelling evidence that cooperative breeding is associated with elevated cognitive ability or large brains (indeed data suggest the opposite is true in non‐human primates) also casts doubt on the capacity of the CBH to explain variation in cognitive traits.

Sexually selected sentinels? Evidence of a role for intrasexual competition in sentinel behavior

Few studies have considered whether competition between members of the same sex has shaped the expression of cooperative behaviors. Here, we provide experimental evidence that sentinel behavior plays a role in defense against same-sex competitors. Song playbacks that simulated male intrusions elicited a marked increase in sentineling by the dominant male, and also suggested that the sentinel position itself may facilitate the initiation of anti-intruder responses.

Twitter: @Linds__Walker @animalsocieties

Although the evolutionary mechanisms that favor investment in cooperative behaviors have long been a focus of research, comparatively few studies have considered the role that sexual selection may play. For example, evolutionary explanations for sentinel behavior (where 1 individual assumes an elevated position and scans the surroundings while other group members forage nearby) have traditionally focused on the inclusive fitness benefits arising from its effects on predation risk, while its potential role in defense against intrasexual competitors remains largely unexplored. Here, we provide experimental evidence of a role for sentinel behavior in intrasexual competition, in a cooperatively breeding songbird, the white-browed sparrow weaver (Plocepasser mahali). First, dominant males sentinel substantially more than other group members (even when controlling for variation in age and body condition), consistent with a role for sentineling in intrasexual competition for mates and/or territory. Second, experimental playback of an unfamiliar male’s solo song elicited a marked increase in sentineling by the dominant male, and the vocal response to the playback also positively predicted his sentinel effort following the simulated intrusion. A second experiment also suggests that sentineling may facilitate mounting rapid anti-intruder responses, as responses to intruder-playback occurred significantly earlier when the dominant male was sentineling rather than foraging at playback onset. Together, our findings provide rare support for the hypothesis that sentinel behavior plays a role in intrasexual competition, and so highlight the potential for sexually selected direct benefits to shape its expression in this and other social vertebrates.

Altered Appetite-Mediating Hormone Concentrations Precede Compensatory Overeating After Severe, Short-Term Energy Deprivation in Healthy Adults

BACKGROUND

Adaptive responses of appetite-mediating hormones to negative energy balance are thought to contribute to a counterregulatory response that drives weight regain, but they have not been studied while controlling for reduced diet volume.

OBJECTIVE

In this secondary analysis, we aimed to determine the effects of short-term, severe energy deprivation (ED) on appetite and appetite-mediating hormone concentrations.

METHODS

Twenty-one adults with a mean ± SD age of 21 ± 3 y and body mass index of 25 ± 3 kg/m(2) consumed isovolumetric diets provided over separate 48-h periods while increasing habitual energy expenditure by 1683 ± 329 kcal/d through light- and moderate-intensity exercise. Energy intake was matched to energy expenditure to maintain energy balance (EB) (-44 ± 92 kcal/d) or was <10% of energy expenditure to generate a -3696 ± 742-kcal/d energy deficit. Postprandial appetite, glucose, insulin, acyl ghrelin, peptide YY, pancreatic polypeptide (PP), and glucagon-like peptide-1 (GLP-1) responses and ad libitum energy intake were measured as secondary outcomes after both experimental periods.

RESULTS

Fasting insulin (-56% ± 42%) and acyl ghrelin (-60% ± 17%) concentrations decreased during ED but not during EB (condition-by-time interaction; P-interaction ≤ 0.01), whereas fasting leptin concentrations decreased more during ED compared with during EB (-47% ± 27% compared with -20% ± 27%; P-interaction = 0.05). Postprandial insulin (57% ± 63%; P < 0.001), GLP-1 (14% ± 28%; P = 0.04), and PP (54% ± 52%; P < 0.001) areas under the curve (AUCs) were higher, whereas the acyl ghrelin AUC was lower (-56% ± 13%; P < 0.001) after ED compared with after EB. After ED, self-rated appetite was greater, and ad libitum energy intake was 811 kcal/36 h (95% CI: 184, 1439 kcal/36 h) higher relative to after EB (P = 0.01).

CONCLUSIONS

Short-term, severe ED suppressed acyl ghrelin concentrations and increased postprandial anorexigenic hormone concentrations. These effects preceded compensatory overeating, suggesting that in adults without obesity, altered sensitivity to appetite-mediating hormones may contribute to an adaptive counterregulatory response during the initial stages of negative EB. This trial was registered at clinicaltrials.gov as NCT01603550.

Dominant male song performance reflects current immune state in a cooperatively breeding songbird

Conspicuous displays are thought to have evolved as signals of individual “quality”, though precisely what they encode remains a focus of debate. While high quality signals may be produced by high quality individuals due to “good genes” or favourable early‐life conditions, whether current immune state also impacts signalling performance remains poorly understood, particularly in social species. Here, we experimentally demonstrate that male song performance is impaired by immune system activation in the cooperatively breeding white‐browed sparrow weaver (Plocepasser mahali). We experimentally activated the immune system of free‐living dominant males via subcutaneous injection of phytohemagglutinin (PHA) and contrasted its effects with those of a control (phosphate buffered saline) injection. PHA‐challenged males showed significant reductions in both the duration and the rate of their song performance, relative to controls, and this could not be readily attributed to effects of the challenge on body mass, as no such effects were detected. Furthermore, male song performance prior to immune‐challenge predicted the scale of the inflammatory response to the challenge. Our findings suggest that song performance characteristics are impacted by current immune state. This link between current state and signal performance might therefore contribute to enforcing the honesty of signal performance characteristics. Impacts of current state on signaling may be of particular importance in social species, where subordinates may benefit from an ability to identify and subsequently challenge same‐sex dominants in a weakened state.

Phytonutrients Differentially Stimulate NAD(P)H:Quinone Oxidoreductase, Inhibit Proliferation, and Trigger Mitotic Catastrophe in Hepa1c1c7 Cells

Phytonutrients have rapidly emerged as natural food chemicals possessing multifaceted biological actions that may support beneficial health outcomes. Among the vast array of phytonutrients currently being studied, sulforaphane, curcumin, quercetin, and resveratrol have been frequently reported to stimulate the expression of endogenous detoxification enzymes and may thereby facilitate the neutralization of otherwise harmful environmental agents. Some of these same phytonutrients, however, have also been implicated in disrupting normal cell proliferation and hence may possess toxic properties in and of themselves. In this study, we characterize the respective minimum threshold concentrations of the aforementioned phytonutrients in Hepa1c1c7 cells that stimulate

NAD(P)H

quinone oxidoreductase (NQO1), a key enzyme in the hepatic neutralization of menadione, other biological oxidants, and some environmental carcinogens. Moreover, our findings demonstrate that relatively low concentrations of either sulforaphane or curcumin significantly (P < .05) increase NQO1 protein expression and activity without triggering G2/M cell cycle arrest or mitotic catastrophe. The minimal quercetin concentration inducing NQO1, however, was 100-fold higher than that which disrupted mitosis. Also, while resveratrol modestly stimulated NQO1, the minimally effective resveratrol concentration concomitantly induced evidence of cellular apoptosis. Taken together, these findings indicate that only particular phytonutrients are likely efficacious in upregulating NQO1 activity without also leading to hepatic cytotoxicity.

Human Muscle Protein Synthetic Responses during Weight-Bearing and Non-Weight-Bearing Exercise: A Comparative Study of Exercise Modes and Recovery Nutrition

Effects of conventional endurance (CE) exercise and essential amino acid (EAA) supplementation on protein turnover are well described. Protein turnover responses to weighted endurance exercise (i.e., load carriage, LC) and EAA may differ from CE, because the mechanical forces and contractile properties of LC and CE likely differ. This study examined muscle protein synthesis (MPS) and whole-body protein turnover in response to LC and CE, with and without EAA supplementation, using stable isotope amino acid tracer infusions. Forty adults (mean ± SD, 22 ± 4 y, 80 ± 10 kg, VO_2peak 4.0 ± 0.5 L∙min^-1) were randomly assigned to perform 90 min, absolute intensity-matched (2.2 ± 0.1 VO₂ L∙m^-1) LC (performed on a treadmill wearing a vest equal to 30% of individual body mass, mean ± SD load carried 24 ± 3 kg) or CE (cycle ergometry performed at the same absolute VO₂ as LC) exercise, during which EAA (10 g EAA, 3.6 g leucine) or control (CON, non-nutritive) drinks were consumed. Mixed-muscle and myofibrillar MPS were higher during exercise for LC than CE (mode main effect, P < 0.05), independent of dietary treatment. EAA enhanced mixed-muscle and sarcoplasmic MPS during exercise, regardless of mode (drink main effect, P < 0.05). Mixed-muscle and sarcoplasmic MPS were higher in recovery for LC than CE (mode main effect, P < 0.05). No other differences or interactions (mode x drink) were observed. However, EAA attenuated whole-body protein breakdown, increased amino acid oxidation, and enhanced net protein balance in recovery compared to CON, regardless of exercise mode (P < 0.05). These data show that, although whole-body protein turnover responses to absolute VO₂-matched LC and CE are the same, LC elicited a greater muscle protein synthetic response than CE.

Effects of feeding birdsfoot trefoil hay on neutral detergent fiber digestion, nitrogen utilization efficiency, and lactational performance by dairy cows

This experiment was conducted to determine effects of feeding birdsfoot trefoil hay-based diets in comparison with an alfalfa hay-based diet on N utilization efficiency, ruminal fermentation, and lactational performance by mid-lactation dairy cows. Nine multiparous lactating Holstein cows (131 ± 22.6 d in milk), 3 of which were rumen fistulated, were fed 3 experimental diets in a replicated 3 × 3 Latin square design with 3 periods of 14 d of adaptation and 7 d of data and sample collection. Within squares, cows were randomly assigned to diets as follows: alfalfa hay-based diet (AHT), alfalfa and birdsfoot trefoil hay-based diet (ABT), and birdsfoot trefoil hay-based diet (BT). Intakes of dry matter and crude protein were similar across treatments, whereas ABT and BT diets resulted in decreased fiber intake compared with AHT. Feeding BT tended to increase neutral detergent fiber digestibility compared with AHT and ABT. Milk yield tended to increase for cows consuming ABT or BT diets. Milk true protein concentration and yield were greater for cows consuming ABT relative to those fed AHT. Concentration of total volatile fatty acids tended to increase by cows fed BT compared with those fed AHT and ABT. Feeding birdsfoot trefoil hay in a total mixed ration resulted in a tendency to decrease acetate proportion, but it tended to increase propionate proportion, leading to a tendency to decrease acetate-to-propionate ratio. Whereas concentration of ammonia-N was similar across treatments, cows offered BT exhibited greater microbial protein yield relative to those fed AHT and ABT. Cows offered birdsfoot trefoil hay diets secreted more milk N than AHT, resulting in improved N utilization efficiency for milk N. The positive effects due to feeding birdsfoot trefoil hay were attributed to enhanced neutral detergent fiber digestion, and thus it could replace alfalfa hay in high-forage dairy diets while improving N utilization efficiencies and maintaining lactational performance compared with alfalfa hay.

Assessing Incidence and Risk Factors of Cervical Spine Injury in Blunt Trauma Patients Using the National Trauma Data Bank

Despite the potentially devastating impact of missed cervical spine injuries (CI), there continues to be a large disparity in how institutions attempt to make the diagnosis. To better streamline the approach among institutions, understanding incidence and risk factors across the country is paramount. We evaluated the incidence and risk factors of CI using the National Trauma Databank for 2008 and 2009. We performed a retrospective review of the National Trauma Databank for 2008 and 2009 comparing patients with and without CI. We then performed subset analysis separating injury by patients with and without fracture and ligamentous injury. There were a total of 591,138 patients included with a 6.2 per cent incidence of CI. Regression found that age, Injury Severity Score, alcohol intoxication, and specific mechanisms of motor vehicle crash (MVC), motorcycle crash (MCC), fall, pedestrian stuck, and bicycle were independent risk factors for overall injury ( P < 0.0001). Patients with CI had longer intensive care unit (8.5 12.5 vs 5.1 7.7) and hospital lengths of stay (days) (9.6 14.2 vs 5.3 8.1) and higher mortality (1.2 per cent vs 0.3%), compared with those without injury ( P < 0.0001). There were 33,276 patient with only fractures for an incidence of 5.6 per cent and 1875 patients with ligamentous injury. Just over 6 per cent of patients suffer some form of CI after blunt trauma with the majority being fractures. Higher Injury Severity Score and MVC were consistent risk factors in both groups. This information will assist in devising an algorithm for clearance that can be used nationally allowing for more consistency among trauma providers.

Assessing Incidence and Risk Factors of Cervical Spine Injury in Blunt Trauma Patients Using the National Trauma Data Bank

Despite the potentially devastating impact of missed cervical spine injuries (CI), there continues to be a large disparity in how institutions attempt to make the diagnosis. To better streamline the approach among institutions, understanding incidence and risk factors across the country is paramount. We evaluated the incidence and risk factors of CI using the National Trauma Databank for 2008 and 2009. We performed a retrospective review of the National Trauma Databank for 2008 and 2009 comparing patients with and without CI. We then performed subset analysis separating injury by patients with and without fracture and ligamentous injury. There were a total of 591,138 patients included with a 6.2 per cent incidence of CI. Regression found that age, Injury Severity Score, alcohol intoxication, and specific mechanisms of motor vehicle crash (MVC), motorcycle crash (MCC), fall, pedestrian stuck, and bicycle were independent risk factors for overall injury (P < 0.0001). Patients with CI had longer intensive care unit (8.5 12.5 vs 5.1 7.7) and hospital lengths of stay (days) (9.6 14.2 vs 5.3 8.1) and higher mortality (1.2 per cent vs 0.3%), compared with those without injury (P < 0.0001). There were 33,276 patient with only fractures for an incidence of 5.6 per cent and 1875 patients with ligamentous injury. Just over 6 per cent of patients suffer some form of CI after blunt trauma with the majority being fractures. Higher Injury Severity Score and MVC were consistent risk factors in both groups. This information will assist in devising an algorithm for clearance that can be used nationally allowing for more consistency among trauma providers.

Workforce Effects and the Evolution of Complex Sociality in Wild Damaraland Mole Rats

Explaining the evolution of eusocial and cooperatively breeding societies demands that we understand the effects of workforce size on the reproductive success of breeders. This challenge has yet to be addressed in the family that arguably exhibits the most extreme outcomes of vertebrate social evolution, the African mole rats (Bathyergidae), leaving the ultimate causes of their many unusual adaptations open to debate. Here we report-using a 14-year field study of wild Damaraland mole rats, Fukomys damarensis-that workers appear to have strong but unusual effects on offspring. Groups with larger workforces exhibited substantially higher rates of offspring recruitment while maintaining high juvenile survival rates, relationships that may have favored the evolution of the delayed dispersal, cooperation, morphological specialization, and unusual patterns of longevity that characterize such societies. Offspring reared by larger workforces also showed slower growth, however. That reduced offspring growth in larger groups has also been documented under ad lib. food conditions in the laboratory raises the possibility that this reflects socially induced growth restraint rather than simple constraints on resource availability. Our findings shed new light on the evolution of complex sociality in this enigmatic clade and highlight further departures from the norms reported for other cooperative vertebrates.

Absorption of omega-3 fats from carbohydrate and proteinaceous food matrices before and after storage

Development of n-3 fortified, shelf-stable foods is facilitated by encapsulated docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), since natural n-3 food sources cannot withstand high temperature and prolonged shelf life. Organoleptic stability of n-3 fortified, shelf-stable foods has been demonstrated, but chemical changes in the food matrix throughout storage could conceivably impact digestibility of the protein-based encapsulant thereby compromising n-3 bioavailability. We assessed the effect of prolonged high-temperature storage and variations in food matrix (proteinaceous or carbohydrate) on the time course and magnitude of blood fatty acids changes associated with ingestion of n-3 fortified foods. Low-protein (i.e., cake) and high-protein (i.e., meat sticks) items were supplemented with 600 mg encapsulated DHA+EPA, and frozen either immediately after production (FRESH) or after 6 months storage at 100°F (STORED). Fourteen volunteers consumed one item per week (randomized) for 4 weeks. Blood samples obtained at baseline, 2, 4, and 6 h post-consumption were analyzed for circulating long-chain omega 3 fatty acids (LCn3). There was no difference in LCn3 area under the curve between items. LCn3 in response to cakes peaked at 2-h (FRESH: 54.0 ± 16.8 μg/mL, +18%; STORED: 53.0 ± 13.2 μg/mL, +20%), while meats peaked at 4-h (FRESH: 51.9 ± 12.5 μg/mL, +22%; STORED: 53.2 ± 16.9 μg/mL, +18%). There were no appreciable differences in time course or magnitude of n-3 appearance in response to storage conditions for either food types. Thus, bioavailability of encapsulated DHA/EPA, within low- and high-protein food items, was not affected by high-temperature shelf-storage. A shelf-stable, low- or high-protein food item with encapsulated DHA/EPA is suitable for use in shelf-stable foods.

Effects of basic combat training on iron status in male and female soldiers: a comparative study

OBJECTIVE

Iron is an essential micronutrient known to affect physical and cognitive performance. Studies indicate a significant reduction in iron status in female Soldiers immediately following military training, although the comparative effects of military training on iron status between male and female Soldiers have not been examined. The objective of this study was to compare the longitudinal effects of US Army basic combat training (BCT) on iron status indicators in a group of male and female Soldiers.

METHODS

A total of 154 male and female Soldiers (89 and 65, respectively) completed the study. Blood was collected at 4 time-points during BCT (weeks 0, 3, 6, 9) and dietary iron intake was assessed at weeks 0 and 9. Iron status indicators included hemoglobin, serum ferritin (SF), soluble transferrin receptor (sTfR), and transferrin saturation (TS).

RESULTS

Iron status was greater in male Soldiers than female Soldiers, as hemoglobin and SF levels were higher (P<.05) and sTfR levels were lower (P<.05) in males as compared to females at each time-point. Despite a mean increase of greater than 25% in iron intake (mg/day) among both male (15±13 to 20.2±14.4) and female Soldiers (12.8±9.7 to 16±6.2) over the course of BCT, iron status declined in both groups. As compared to baseline, SF declined (P<.05) by 21% and 47%, sTfR increased (P<.05) by 17% and 30%, and TS declined (P<.05) by 23% and 54% in male and female Soldiers, respectively, over the course of BCT.

CONCLUSIONS

These data indicate that although dietary iron intake improves, iron status declines in both male and female Soldiers during BCT, and the decline in female Soldiers is of a greater magnitude. Future studies should aim to determine the mechanism by which iron status declines during military training, with a focus on functional outcomes affecting Soldier health and performance.

Immune response in a wild bird is predicted by oxidative status, but does not cause oxidative stress

The immune system provides vital protection against pathogens, but extensive evidence suggests that mounting immune responses can entail survival and fecundity costs. The physiological mechanisms that underpin these costs remain poorly understood, despite their potentially important role in shaping life-histories. Recent studies involving laboratory models highlight the possibility that oxidative stress could mediate these costs, as immune-activation can increase the production of reactive oxygen species leading to oxidative stress. However, this hypothesis has rarely been tested in free-ranging wild populations, where natural oxidative statuses and compensatory strategies may moderate immune responses and their impacts on oxidative status. Furthermore, the possibility that individuals scale their immune responses according to their oxidative status, conceivably to mitigate such costs, remains virtually unexplored. Here, we experimentally investigate the effects of a phytohaemagglutinin (PHA) immune-challenge on oxidative status in wild male and female white-browed sparrow weavers, Plocepasser mahali. We also establish whether baseline oxidative status prior to challenge predicts the scale of the immune responses. Contrary to previous work on captive animals, our findings suggest that PHA-induced immune-activation does not elicit oxidative stress. Compared with controls (n = 25 birds), PHA-injected birds (n = 27 birds) showed no evidence of a differential change in markers of oxidative damage or enzymatic and non-enzymatic antioxidant protection 24 hours after challenge. We did, however, find that the activity of a key antioxidant enzyme (superoxide dismutase, SOD) prior to immune-activation predicted the scale of the resulting swelling: birds with stronger initial SOD activity subsequently produced smaller swellings. Our findings (i) suggest that wild birds can mount immune responses without suffering from systemic oxidative stress, and (ii) lend support to biomedical evidence that baseline oxidative status can impact the scale of immune responses; a possibility not yet recognised in ecological studies of immunity.

Trends in overweight and obesity in soldiers entering the US Army, 1989-2012

OBJECTIVE

The US Army recruits new soldiers from an increasingly obese civilian population. The change in weight status at entry into the Army between 1989 and 2012 and the demographic characteristics associated with overweight/obesity at entry were examined.

METHODS

1,741,070 unique individuals with complete sex, age, and anthropometric information contributed data to linear and logistic regressions examining time trends and associations between demographic characteristics and overweight/obesity.

RESULTS

The prevalence of overweight (body mass index 25-<30 kg/m(2)) generally increased, from 25.8% (1989) to 37.2% (2012), peaking at 37.9% (2011). The prevalence of obesity (body mass index ≥30 kg/m(2)) also increased from 5.6% (1989) to 8.0% (2012), peaking at 12.3% (2009); 2005-2009 annual prevalence exceeded 10%. The most consistent demographic characteristics predicting overweight/obesity were male sex, older age, Hispanic or Asian/Pacific Island race/ethnicity, and being married. There were no distinct geographic trends.

CONCLUSIONS

The US Army is not immune to the US obesity epidemic. Demographic characteristics associated with being overweight or obese should be considered when developing military-sponsored weight management programs for new soldiers.