Ontogeny of the hominoid scapula: The influence of locomotion on morphology

Primate shoulder morphology has been linked with locomotor habits, oftentimes irrespective of phylogenetic heritage. Among hominoids, juvenile African apes are known to climb more frequently than adults, while orangutans and gibbons maintain an arboreal lifestyle throughout ontogeny. This study examined if these ontogenetic locomotor differences carry a morphological signal, which should be evident in the scapulae of chimpanzees and gorillas but absent in taxa that do not display ontogenetic behavioral shifts. The scapular morphology of five hominoid primates and one catarrhine outgroup was examined throughout ontogeny to evaluate if scapular traits linked with arboreal activities are modified in response to ontogenetic behavioral shifts away from climbing. Specifically, the following questions were addressed: 1) which scapular characteristics distinguish taxa with different locomotor habits; and 2) do these traits show associated changes during development in taxa known to modify their behavioral patterns? Several traits characterized suspensory taxa from nonsuspensory forms, such as cranially oriented glenohumeral joints, obliquely oriented scapular spines, relatively narrow infraspinous fossae, and inferolaterally expanded subscapularis fossae. The relative shape of the dorsal scapular fossae changed in Pan, Gorilla, and also Macaca in line with predictions based on reported ontogenetic changes in locomotor behavior. These morphological changes were mostly distinct from those seen in Pongo, Hylobates, and Homo and imply a unique developmental pattern, possibly related to ontogenetic locomotor shifts. Accordingly, features that sorted taxa by locomotor habits and changed in concert with ontogenetic behavioral patterns should be particularly useful for reconstructing the locomotor habits of fossil forms.

Effects of 6 months glucagon-like peptide-1 receptor agonist treatment on endothelial function in type 2 diabetes mellitus patients

Glucagon-like peptide-1 receptor agonists (GLP-1 RA) are used for treatment in type 2 diabetes mellitus (T2DM). Little is known about their cardiovascular (CV) impact. We sought to determine the effects of chronic treatment on vascular function in T2DM. Brachial artery endothelial-dependent flow-mediated dilation (FMD) and endothelial-independent glyceryl trinitrate (GTN) function and carotid intima-medial thickness (cIMT) were assessed in 11 severely obese T2DMs (4 females, 7 males: 55 ± 8 years, diabetes duration 8.3 ± 4.7 years mean ± s.d.) before and after 6 months GLP-1 RA. Body weight (5.3 ± 1.2 kg; p < 0.05) and magnetic resonance imaging determined total and subcutaneous fat, but not visceral fat, decreased. Glycaemic control improved. There were no significant changes in FMD, GTN and cIMT (-1.1 ± 0.4%, 0.3 ± 3.0% and 0.00 ± 0.04 mm, respectively). Despite significant improvements in body composition and glycaemic control, 6 months GLP-1 RA treatment did not modulate vascular function. Alternative strategies may therefore be needed to reduce the burden of CV risk in severely obese patients with long-standing T2DM.

Nitric oxide-mediated cutaneous microvascular function is impaired in polycystic ovary sydrome but can be improved by exercise training

Polycystic ovary syndrome (PCOS) is associated with cardiovascular disease. The contribution of the nitric oxide (NO) dilator system to cutaneous endothelial dysfunction is currently unknown in PCOS. Our aim was to examine whether women with PCOS demonstrate impaired cutaneous microvascular NO function and whether exercise training can ameliorate any impairment. Eleven women with PCOS (age, 29 ± 7 years; body mass index, 34 ± 6 kg m(-2)) were compared with six healthy obese control women (age, 29 ± 7 years; body mass index, 34 ± 5 kg m(-2)). Six women with PCOS (30 ± 7 years; 31 ± 6 kg m(-2)) then completed 16 weeks of exercise training. Laser Doppler flowmetry, combined with intradermal microdialysis of l-N(G)-monomethyl-l-arginine, a nitric oxide antagonist, in response to incremental local heating of the forearm was assessed in women with PCOS and control women, and again in women with PCOS following exercise training. Cardiorespiratory fitness, homeostasis model assessment for insulin resistance, hormone and lipid profiles were also assessed. Differences between women with PCOS and control women and changes with exercise were analysed using Student's unpaired t tests. Differences in the contribution of NO to cutaneous blood flow [expressed as a percentage of maximal cutaneous vasodilatation (CVCmax)] were analysed using general linear models. At 42°C heating, cutaneous NO-mediated vasodilatation was attenuated by 17.5%CVCmax (95% confidence interval, 33.3, 1.7; P = 0.03) in women with PCOS vs. control women. Exercise training improved cardiorespiratory fitness by 5.0 ml kg(-1) min(-1) (95% confidence interval, 0.9, 9.2; P = 0.03) and NO-mediated cutaneous vasodilatation at 42°C heating by 19.6% CVCmax (95% confidence interval, 4.3, 34.9; P = 0.02). Cutaneous microvascular NO function is impaired in women with PCOS compared with obese matched control women but can be improved with exercise training.

Effects of exercise intensity on flow mediated dilation in healthy humans

Previous studies have demonstrated conflicting results on the effects of acute exercise on FMD. The aim of the study was to examine brachial artery FMD before and after 3 bouts of acute exercise performed at different intensities. 10 healthy males (mean±SD age: 22±1 years) completed 30 min of cycling at 50, 70 and 85% maximal heart rate (HRmax). Brachial artery FMD and the shear rate area-under-the-curve (cuff deflation to peak dilation; SRAUC) were assessed pre- and immediately post-exercise using high-resolution echo-Doppler. A generalized estimating equation (GEE) analysis was used to estimate the effect magnitudes of exercise intensity and time (pre/post) on FMD, whilst controlling for the influence of baseline diameter and SRAUC. Both baseline diameter and SRAUC were elevated by exercise. With covariate-control of these variables, the decrease in brachial artery FMD was negligible after exercise at 50% HRmax (6.3±2.6 vs. 5.9±2.5%; 95%CI for difference: - 0.59-1.34%) with larger decreases in FMD after exercise at 70% (6.1±1.8 vs. 4.7±1.9%; 95%CI for difference: 0.08-2.58%) and at 85% HRmax (6.6±1.6 vs. 3.6±2.2%; 95%CI: 0.41-5.42%). In conclusion, even after accounting for exercise-mediated changes in shear and baseline diameter, our data indicate that a negative relationship exists between exercise intensity and FMD.

Mouse shoulder morphology responds to locomotor activity and the kinematic differences of climbing and running

Mechanical loads play a significant role in determining long bone shape and strength, but less work has explored how these loads influence flat bones like the scapula, which has been shown to vary with locomotor preference among primate taxa. Here, we tested the effects of voluntary running and climbing exercise in mice to examine how the mechanical loads borne from different locomotor patterns influence shoulder morphological development. Ninety-nine female wild-type mice were distributed equally among sedentary control, activity-wheel running, and vertical climbing experimental conditions. Running mice had the lowest body masses, larger intrinsic shoulder muscles, and the most pronounced differences in scapular size and shape relative to the other groups. Climbing mouse scapular morphology also differed significantly from the control individuals, but these differences were not as marked as those between the running and control mice. This might be attributable in part to greater levels of activity in the wheel-runners relative to the climbers. Additionally, climbing mice held their bodies closer to the substrate and maintained more flexed limbs and posterior hand positions compared with the kinematics of running. As a result, climbers differed significantly from both the running and control mice in developing a relatively broader infraspinous region, which is likely related to preferential recruitment of the infraspinatus and teres minor muscles to maintain flexed shoulder postures. The results of this study demonstrate that variation in activity level and type of locomotor regime over a significant portion of the life history influences muscle and bone development in the shoulder.

Factors associated with primary care prescription of opioids for joint pain

BACKGROUND

Opioids are commonly prescribed in primary care and can offer pain relief but may also have adverse effects. Little is known about the characteristics of people likely to receive an opioid prescription in primary care. The aim is to identify what factors are associated with primary care prescribing of high-strength analgesics in a community sample of older people with joint pain.

METHODS

A prospective two-stage postal survey completed at baseline and 3-year follow-up in a population aged 50 and over registered with eight general practitioner (GP) practices in North Staffordshire (North Staffordshire Osteoarthritis Project cohorts) linked with data from medical records. Participants were selected who reported joint pain in one or more joints at baseline. Outcome measures were the number of prescriptions for high-strength pain medication (opioids) in the following 3 years. Socio-demographic and health status factors associated with prescription were assessed using a zero-inflated Poisson model.

RESULTS

873 (19%) people were prescribed opioids (out of 4652 providing complete data) ranging from 1 to 76 prescriptions over 3 years. Baseline factors significantly associated with increased rates of prescription were younger age group [65-74 group: incidence rate ratio (IRR) = 1.26 (1.18-1.35)], male gender [IRR = 1.17 (1.12-1.23)], severe joint pain [IRR = 1.19 (1.12-1.26)] poor physical function [IRR = 0.99 (0.99-0.99)] and lower frequency of alcohol consumption [once/twice a year: IRR = 1.13 (1.06-1.21), never: IRR = 1.14 (1.06-1.22)]. Restricting the analysis to those without prior prescriptions for strong opioids showed similar results.

CONCLUSION

Poor physical function and participation restrictions were strongly associated with prescriptions of stronger opioids in addition to several socio-demographic and lifestyle factors. Given the uncertainties over the effectiveness and risks of opioid use, future research could investigate decision making of GPs, exploring reasons for prescribing them.

Anthropogenic landscape change promotes asymmetric dispersal and limits regional patch occupancy in a spatially structured bird population

1. Local extinctions in habitat patches and asymmetric dispersal between patches are key processes structuring animal populations in heterogeneous environments. Effective landscape conservation requires an understanding of how habitat loss and fragmentation influence demographic processes within populations and movement between populations. 2. We used patch occupancy surveys and molecular data for a rainforest bird, the logrunner (Orthonyx temminckii), to determine (i) the effects of landscape change and patch structure on local extinction; (ii) the asymmetry of emigration and immigration rates; (iii) the relative influence of local and between-population landscapes on asymmetric emigration and immigration; and (iv) the relative contributions of habitat loss and habitat fragmentation to asymmetric emigration and immigration. 3. Whether or not a patch was occupied by logrunners was primarily determined by the isolation of that patch. After controlling for patch isolation, patch occupancy declined in landscapes experiencing high levels of rainforest loss over the last 100 years. Habitat loss and fragmentation over the last century was more important than the current pattern of patch isolation alone, which suggested that immigration from neighbouring patches was unable to prevent local extinction in highly modified landscapes. 4. We discovered that dispersal between logrunner populations is highly asymmetric. Emigration rates were 39% lower when local landscapes were fragmented, but emigration was not limited by the structure of the between-population landscapes. In contrast, immigration was 37% greater when local landscapes were fragmented and was lower when the between-population landscapes were fragmented. Rainforest fragmentation influenced asymmetric dispersal to a greater extent than did rainforest loss, and a 60% reduction in mean patch area was capable of switching a population from being a net exporter to a net importer of dispersing logrunners. 5. The synergistic effects of landscape change on species occurrence and asymmetric dispersal have important implications for conservation. Conservation measures that maintain large patch sizes in the landscape may promote asymmetric dispersal from intact to fragmented landscapes and allow rainforest bird populations to persist in fragmented and degraded landscapes. These sink populations could form the kernel of source populations given sufficient habitat restoration. However, the success of this rescue effect will depend on the quality of the between-population landscapes.

The impact of exercise training on the diameter dilator response to forearm ischaemia in healthy men

AIM

Recent studies found differences between groups in the rate of diameter increase following the flow-mediated dilation (FMD). Whilst exercise training alters the magnitude of the FMD, little is known about the impact of exercise training on the rate of diameter increase. The aim of this study is to examine post-cuff deflation changes in brachial artery diameter following 5 min forearm ischaemia every 2 weeks across 8-weeks of a handgrip exercise training regimen.

METHODS

Post-deflation changes in brachial artery diameter following 5-min of ischaemia were examined before, after and every 2-weeks across an 8-week handgrip training programme in healthy young men (n = 11) using echo-Doppler.

RESULTS

The magnitude of dilation increased at week 2-4-6, but returned towards baseline values at week 8 (anova: P = 8.001). The time-to-peak diameter (42 ± 15s) demonstrated a significant prolongation at week 4 (77 ± 32s), but returned towards baseline values at weeks 6 and 8 (anova: P < 0.001). The rate of diameter increase did not differ across the intervention.

CONCLUSION

Exercise training in healthy subjects is initially characterized by a larger dilation. Since the rate of dilation did not change, a longer time-to-peak dilation was necessary to achieve the increase in magnitude of dilation. As exercise training continues, the timing and magnitude of the peak diameter response returns to near baseline levels.

Effects of exercise on endothelium and endothelium/smooth muscle cross talk: role of exercise-induced hemodynamics

Physical activity, exercise training, and fitness are associated with decreased cardiovascular risk. In the context that a risk factor "gap" exists in the explanation for the beneficial effects of exercise on cardiovascular disease, it has recently been proposed that exercise generates hemodynamic stimuli which exert direct effects on the vasculature that are antiatherogenic. In this review we briefly introduce some of the in vitro and in vivo evidence relating exercise hemodynamic modulation and vascular adaptation. In vitro data clearly demonstrate the importance of shear stress as a potential mechanism underlying vascular adaptations associated with exercise. Supporting this is in vivo human data demonstrating that exercise-mediated shear stress induces localized impacts on arterial function and diameter. Emerging evidence suggests that exercise-related changes in hemodynamic stimuli other than shear stress may also be associated with arterial remodeling. Taken together, in vitro and in vivo data strongly imply that hemodynamic influences combine to orchestrate a response to exercise and training that regulates wall stress and peripheral vascular resistance and contributes to the antiatherogenic impacts of physical activity, fitness, and training.

The effects of hypermuscularity on shoulder morphology in myostatin-deficient mice

Mechanical loads, particularly those generated by skeletal muscle, play a significant role in determining long-bone shape and strength, but it is less clear how these loads influence the morphology of flat bones like the scapula. While scapular morphology has been shown to vary with locomotor mode in mammals, this study seeks to better understand whether genetically modified muscle size can influence scapular shape in the absence of significant locomotor differences. The soft- and hard-tissue morphological characteristics were examined in 11 hypermuscular, mutant (myostatin-deficient), 20 heterozygote, and 15 wild-type mouse shoulders. Body mass did not significantly differ among the genotype groups, but homozygous mutant and heterozygote mice had significantly larger shoulder muscles than wild-type mice. Mutant mice also differed significantly from the wild-type controls in several aspects of scapular size and shape, including glenohumeral joint orientation, total scapular length, superior border length, and supraspinous and infraspinous fossa length. Conversely, several traits describing superoinferior scapular breadth measures (e.g. total breadth and dorsal scapular fossa breadth) did not significantly differ between mutant and wild-type mice. Since the intrinsic musculature of the scapula is oriented in a mediolateral fashion, it follows that mediolaterally configured hard-tissue features like scapular length were most distinct among genotype groups. As had been noted previously with long bones, this study demonstrates that genetically enhanced muscle size has marked effects on the morphological characteristics of the shoulder.

Mechanical Behavior of a Cellular-Core Ceramic Sandwich System

The failure behavior and stress distribution of a novel ceramic sandwich system was investigated. A highly porous, open-cell A12O3 was used as the core material with relative densities ranging from 9% to 20%. The faceplates were dense A12O3 of varying thickness. The composites were tested in flexure and failure loads of the cellular core were shown to compare favorably to those predicted by theory when Weibull statistics were incorporated. Stresses in the tensile faceplates were also measured. For composites with relatively thick faces and low modulus cores, the stress distribution was significantly altered by a local bending effect. These stresses were predicted using a refined model.

Thermal Shock Behavior of Open Cell Ceramic Foams

Specimens of heated alumina foams were thermally shocked by immersion in water or oil. Two distinct temperature profiles were found to exist during liquid quenching: a macroscopic gradient due to heating of the fluid during infiltration into the foam and a microscopic gradient across each individual strut. Thermal stresses were calculated using a semi-empirical, finite element model. The peak thermal stresses were coupled with the two-parameter Weibull distribution of the strut strengths to calculate the probability of crack extension on a strut for eight cellular geometries. Experimentally, the thermal shock resistance increased with increasing relative density and increasing cell size. The predicted critical temperature differences were in fair agreement with measured values.

The relationship between post-traumatic ventilator-associated pneumonia outcomes and American College of Surgeons trauma centre designation

INTRODUCTION

The relationship between outcomes following severe trauma and American College of Surgeons (ACS) trauma centre designation has been studied. Little is known, however, about the association between ACS level and outcomes associated with ventilator-associated pneumonia (VAP).

METHODS

The National Trauma Databank (NTDB, Version 5.0) was queried to identify adult (age 18)trauma patients who (1) developed VAP and (2) were admitted to either an ACS level I or level II centre.Transfer and burn patients were excluded. Univariate analysis defined differences between patient cohorts. Logistic regression analysis was utilised to identify independent risk factors for mortality.

RESULTS

A total of 3465 patients were identified where 65.6% were admitted to a level I facility and 34.4%to a level II centre. Patients admitted to a level I centre were more likely to have an age > 55 (71.5% vs.66.8%, p = 0.004) and to be hypotensive (SBP < 90) on admission (16.2% vs. 13.6%, p = 0.042). They were also more likely to have a longer duration of mechanical ventilation (18.5 days vs. 16.5 days, p = 0.001),longer hospital LOS (34.2 days vs. 29.6 days, p < 0.001) and a higher rate of early (±7 days) tracheostomy(33.1% vs. 29.1%, p = 0.017). Level I admission was, however, associated with lower mortality rates (10.8%vs. 14.7%, p = 0.001) and a higher likelihood of achieving discharge to home (20.2% vs. 16.1%, p < 0.001).Logistic regression analysis identified admission to a level II facility as an independent risk factor for mortality (OR 1.34, 95% CI 1.08–1.66; p = 0.008) in patients developing post-traumatic VAP.

CONCLUSION

For adults who develop VAP after trauma, admission to a level I facility is associated with improved survival. Further prospective study is needed.

Experimental studies of the role of the little raven (Corvus mellori) in surveillance for West Nile virus in Australia

OBJECTIVE

To study the potential role of an Australian corvid, the little raven (Corvus mellori), in the surveillance for exotic West Nile virus (WNV) in Australia.

METHOD

In a series of trials, little ravens were infected with WNV (strain 4132 New York 1999) and Kunjin virus (strain K42886) by the intramuscular route. They were observed for 20 days during which blood and swab samples were taken for virus isolation. Tissue samples were taken from ravens humanely killed during the acute infection period, and at the termination of the trials, for virus isolation, histopathology and immunohistochemistry.

RESULTS

Ravens infected with WNV became mildly ill, but all recovered and seroconverted. Blood virus titres peaked around 3 to 4 days after inoculation at levels between 10(3.0) to 10(7.5) plaque forming units/mL. Virus or viral antigen was detected in spleen, liver, lung, kidney, intestine, testis and ovary by virus isolation and/or immunohistochemistry. WNV was detected in oral and cloacal swabs from 2 to 7 days post inoculation. The molecular and pathogenic characteristics of the inocula were consistent with them being of high virulence, as expected for this isolate. Ravens infected with Kunjin virus developed viraemia and seroconverted, although they did not develop disease.

CONCLUSIONS

Little ravens do not develop severe disease in response to virulent WNV infection and for this reason may not be important sentinel hosts in the event of an outbreak of WNV, as in North America. However, as they have relatively high viraemias, they may be able to support virus cycles.

Does brachial artery flow-mediated dilation scale to anthropometric characteristics?

Flow-mediated dilation (FMD) assesses the health of the vascular endothelium. Despite widespread adoption of scaling practices in cardiac research, scaling for body size or composition has not been used for FMD. The present study investigated the relationships between brachial FMD and body composition in 129 children aged 9-10 (75 female symbol, 54 male symbol), and 50 men aged 16-49. Body composition variables (total, lean, fat mass in the whole body, arm, forearm) were assessed by dual-energy X-ray absorptiometry, FMD was measured in the brachial artery using high-resolution ultrasound. FMD was scaled using simple ratios (y/x) and allometric approaches (y/x ( b )) after log-log least squares linear regression produced allometric exponents (b). Size independence was confirmed via bivariate correlations (x:y/x; x:y/x ( b )). No relationships were evident between FMD and body composition variables in adults. Small correlations existed between FMD and measures of segmental fat mass in children (r = -0.18 to -0.19, p < 0.05), there were no significant relationships between FMD and measures of lean or total mass in children. For all significant relationships, b-exponents were different from 1 (CIs -0.36 to 0.07), suggesting ratio scaling approaches were flawed. This was confirmed when ratio scaling produced negative residual size correlations, whereas allometric scaling produced size-independent indices. Correlations between FMD and body composition were weak in children and insignificant in adults. As the results of this study are limited to the populations examined, our findings do not support the adoption of scaling procedures to correct FMD.

Does conduit artery diameter vary according to the anthropometric characteristics of children or men?

Arterial measurements are commonly undertaken to assess acute and chronic adaptations to exercise. Despite the widespread adoption of scaling practices in cardiac research, the relevance of scaling for body size and/or composition has not been addressed for arterial measures. We therefore investigated the relationships between brachial artery diameter and body composition in 129 children aged 9 to 10 yr (75 girls and 54 boys), and 50 men aged 16-49 yr. Body composition variables (total, lean, and fat mass in the whole body, arm, and forearm) were assessed by dual-energy X-ray absorptiometry, and brachial artery diameter was measured using high-resolution ultrasound. Bivariate correlations were performed, and arterial diameter was then scaled using simple ratios (y/x) and allometric approaches after log-log least squares linear regression and production of allometric exponents (b) and construction of power function ratios (y/xb). Size independence was checked via bivariate correlations (x:y/x; x:y/xb). As a result, significant correlations existed between brachial artery diameter and measures of body mass and lean mass in both cohorts (r=0.21-0.48, P<0.05). There were no significant relationships between diameter and fat mass. All b exponents were significantly different from 1 (0.08-0.50), suggesting that simple ratio scaling approaches were likely to be flawed. This was confirmed when ratio scaling produced negative residual size correlations, whereas allometric scaling produced size-independent indexes (r=0.00 to 0.03, P>0.05). In conclusion, when between- or within-group comparisons are performed under circumstances where it is important to control for differences in body size or composition, allometric scaling of artery diameter should be adopted rather than ratio scaling. Our data also suggest that scaling for lean or total mass may be more appropriate than scaling for indexes of fat mass.

Flow-mediated dilation and intima-media thickness of the brachial and axillary arteries in individuals with and without inducible axillary artery compression

The presence of axillary artery aneurysm and/or thrombus in overhead throwing athletes has been linked, theoretically, with the finding of compression by the humeral head induced by a diagnostic arm maneuver. However, whether this intermittent compression is incidental or of pathological significance has yet to be determined. Flow-mediated vasodilation (FMD), intima-media thickness (IMT) and maximum vasodilatory capacity were measured locally (3rd portion of the axillary artery) and downstream (brachial artery) in individuals previously tested for inducible axillary artery compression (compressor group [COMP]: n=8, mean (SD) age: 23 (4) y; "noncompressor" control group [NONCOMP]: n=8, 26 (4) y). A high-resolution ultrasound machine recorded arterial diameter and blood flow velocity. A rapid inflation/deflation pneumatic cuff placed distal to the site of measurement induced reactive hyperemia. Custom-designed wall tracking software with synchronized Doppler waveform analysis detected changes in arterial diameter, blood flow velocity and shear rate from baseline to 3min after cuff deflation. Glyceryl trinitrate and/or ischemic hand grip exercises were administered to induce maximum vasodilation. No significant differences in FMD, IMT or maximum vasodilator capacity were observed between groups at the axillary artery. However, the downstream brachial FMD response was significantly diminished in the COMP group (6.38 [3.28]%) compared with the NONCOMP group (10.38 [2.74]%; p=0.006) despite a comparable shear rate between groups (COMP: 81.92 (44.55) s(-1); NONCOMP: 83.18 (40.02) s(-1); p=0.961). Pooled data revealed a significant negative relationship (r=-0.52, p=0.038) between the FMD response and degree of arterial compression. These results suggest a chronic change in downstream vascular function in individuals demonstrating clinically significant inducible axillary artery compression.

ACS trauma centre designation and outcomes of post-traumatic ARDS: NTDB analysis and implications for trauma quality improvement

BACKGROUND

Several authors have examined the relationship between outcomes following severe trauma and American College of Surgeons (ACS) trauma centre designation. Little is known, however, about the association between ACS level and outcomes following complications of trauma.

METHODS

The National Trauma Databank (NTDB, v. 5.0) was queried to identify adult (age > or =18) trauma patients developing post-traumatic ARDS, who were admitted to either ACS level 1 or level 2 trauma centres from 2000 to 2004. Patients transferred between institutions and injuries following burns were excluded. Univariate analysis was used to assess differences between those patients admitted to ACS level 1 and level 2 facilities. Adjusted mortality was derived using logistic regression analysis.

RESULTS

A total of 902 adult trauma patients with ARDS after 48 h of mechanical ventilation were identified from the NTDB. Five hundred and thirty six patients were admitted to a level 1 ACS verified centre and 366 to a level 2 facility. Univariate analysis revealed no statistical differences in clinical and demographic characteristics between the two groups. On univariate comparison, patients admitted to level 1 facilities had longer mean hospital and ICU length of stay and higher hospital related charges than level 2 counterparts. Patients admitted to a level 1 centre were, however, significantly more likely to achieve discharge to home. Using multivariate logistic regression, ACS level designation was shown to have no statistical effect on mortality. Hypotension on admission and age greater than 55 were the only independent predictors of mortality.

CONCLUSION

ACS trauma centre designation level is not an independent predictor of mortality following post-traumatic ARDS.

Pyloric exclusion in the treatment of severe duodenal injuries: results from the National Trauma Data Bank

Pyloric exclusion (PEX) has traditionally been used in the management of complicated duodenal injuries to temporarily protect the duodenal repair and prevent septic abdominal complications. We used the American College of Surgeons National Trauma Data Bank (v 5.0) to evaluate adult patients with severe duodenal injuries [American Association for the Surgery of Trauma (AAST) Grade > or = 3] undergoing primary repair only or repair with PEX within 24 hours of admission. Propensity scoring was used to adjust for relevant confounding factors during outcomes comparison. Among 147 patients with severe duodenal injuries, 28 (19.0%) underwent PEX [15.9% (11/69) Grade III vs 34.0% (17/50) Grade IV-V]. Despite similar demographics, PEX was associated with a longer mean hospital stay (32.2 vs 22.2 days, P = 0.003) and was not associated with a mortality benefit. There was a trend toward increased development of septic abdominal complications (intra-abdominal abscess, wound infection, or dehiscence) with PEX that was not statistically significant. After multivariable analysis using propensity score, no statistically significant differences in mortality or occurrence of septic abdominal complications was noted between those patients undergoing primary repair only or PEX. The use of PEX in patients with severe duodenal injuries may contribute to longer hospital stay and confers no survival or outcome benefit.

Life history correlates of alternative migratory strategies in American Dippers

Partial migration is thought to be a critical step in the evolution of avian migration, but data on the life history correlates of alternative migratory strategies are extremely limited. We have studied a partially migratory population of American Dippers since 1999. This population is composed of sedentary individuals (residents) that maintain the same territory year round and altitudinal migrants that share winter grounds with residents, but move to higher elevations to breed. We used seven years of data on individually marked birds to (1) determine if individuals consistently use the same migratory strategy, (2) determine if offspring have the same strategy as their parents, and (3) estimate reproductive and survival rates of the two migratory strategies. We evaluate hypotheses for the persistence of partial migration and discuss their implication for the evolution of migration in sedentary populations. Individual American Dippers rarely switched migratory strategy (4/169 monitored more than one year). An individual's strategy, however, was not always that of its parents, indicating that, while migratory behavior may have a genetic component, environmental or social conditions probably influence the migratory strategy that an individual adopts. Sedentary dippers consistently had higher annual productivity (approximately 1.4 more fledglings/year) than migratory dippers, but mark-recapture models suggested that migratory dippers may have slightly higher survival than residents (approximately 3.4%). Migrants were estimated to have lower lifetime reproductive success than residents because their higher survival was insufficient to offset their lower productivity. Our data suggest that alternative migratory strategies in American Dippers are unlikely to be a fixed genetic dimorphism that persists because the two strategies have equal fitness, or because the relative fitness of the two strategies fluctuates over time. Migratory strategies in American Dippers are more likely to be condition dependent, and the two strategies persist because migrants "make the best of a bad job" by moving to higher elevations to breed. Because migrants obtained no fitness benefits by moving to seasonal breeding territories, our data are consistent with the hypothesis that migration could evolve in sedentary populations if competition for limited resources forces some individuals to seek breeding opportunities outside their initial range.

Relationships between measures of fitness, physical activity, body composition and vascular function in children

BACKGROUND

The prevalence of obesity and physical inactivity in Western countries has increased rapidly. Both are modifiable risk factors for cardiovascular disease. Atherosclerosis begins in childhood and endothelial dysfunction is its earliest detectable manifestation.

METHODS

We assessed flow-mediated dilation (FMD) in 129 children (75 female; 10.3+0.3 yrs; 54 male; 10.4; 0.3 yrs). FMD was normalised for differences in the eliciting shear rate stimulus between subjects (SR(AUC)). Fitness was assessed as peak oxygen uptake during an incremental treadmill exercise test (V O(2)peak). Body composition was measured using a dual-energy X-ray absorptiometry (DEXA) scan. Physical activity (PA) was assessed using Actigraph accelerometers. The cohort was split into tertiles according to FMD% and also FMD% corrected for SR(AUC) to gain insight into the determinants of vascular function.

RESULTS

Across the cohort, significant correlations were observed between FMD%/SR(AUC) and DEXA percentage fat (r=-0.23, p=0.009) and percentage lean mass (r=0.21, p=0.008), and also with PA performed at moderate-to-high intensity (r=0.363, p=0.001). For children in the lowest FMD%/SR(AUC) tertile, a stronger relationship with all PA measures was observed, particularly with high intensity PA (r=0.572, P=0.003). Regression analysis revealed that high intensity PA was the only predictor of impaired FMD%/SR(AUC).

CONCLUSIONS

These data suggest that traditional risk factors for CHD in adult populations impact upon vascular function in young people. Furthermore, it appears that individuals with impaired FMD may benefit from performing high intensity PA, whereas no relationships exist between FMD and lower intensities of PA or between PA and FMD in those subjects who possess preserved vascular function a priori.

Correlates of postfledging survival, the timing of dispersal, and local recruitment in American Dippers

Natal dispersal is a complex process that involves decisions about when to leave the natal territory, how to move through the landscape, and where to settle. We investigated what factors influence the timing of dispersal and local recruitment of American Dippers ( Cinclus mexicanus Swainson, 1827) in Chilliwack, British Columbia. We monitored 102 fledglings from 30 broods between 2003 and 2005. Survival to 5 days after fledging was high (>80%), but individuals fledging early in the season and at an older age had higher survival than those fledging later and younger. Fifty-four percentage of surviving fledglings dispersed within 14 days of nest departure. Females and individuals that spent more time foraging were more likely to disperse within 14 days than males and individuals that foraged less. For those that dispersed, individuals that fledged early in the season and at older ages spent less time in their natal territory. Approximately 10% (10/82) of dispersing individuals were known to recruit locally. Local recruitment of individuals that delayed dispersal was higher than local recruitment of individuals dispersing early. Our study demonstrates that fitness benefits associated with extended natal philopatry are not restricted to cooperatively breeding birds.

Endothelium-dependent and -independent vasodilation of the superficial femoral artery in spinal cord-injured subjects

Extreme inactivity of the legs in spinal cord-injured (SCI) individuals does not result in an impairment of the superficial femoral artery flow-mediated dilation (FMD). To gain insight into the underlying mechanism, the present study examined nitric oxide (NO) responsiveness of vascular smooth muscles in controls and SCI subjects. In eight healthy men (34 +/- 13 yr) and six SCI subjects (37 +/- 10 yr), superficial femoral artery FMD response was assessed by echo Doppler. Subsequently, infusion of incremental dosages of sodium nitroprusside (SNP) was used to assess NO responsiveness. Peak diameter was examined on a second day after 13 min of arterial occlusion in combination with sublingual administration of nitroglycerine. Resting and peak superficial femoral artery diameter in SCI subjects were smaller than in controls (P < 0.001). The FMD response in controls (4.2 +/- 0.9%) was lower than in SCI subjects (8.2 +/- 0.9%, P < 0.001), but not after correcting for area under the curve for shear rate (P = 0.35). When expressed as relative change from baseline, SCI subjects demonstrate a significantly larger diameter increase compared with controls at each dose of SNP. However, when expressed as a relative increase within the range of diameter changes [baseline (0%) - peak diameter (100%)], both groups demonstrate similar changes in response to SNP. Changes in diameter during SNP infusion and FMD response are larger in SCI subjects compared with controls. When these results are corrected, superficial femoral artery FMD and NO sensitivity in SCI subjects are not different from those in controls. This illustrates the importance of appropriate data presentation and suggests that, subsequent to structural inward remodeling of conduit arteries as a consequence of extreme physical inactivity, arterial function is normalized.

Flow-mediated dilatation in the superficial femoral artery is nitric oxide mediated in humans

Flow-mediated dilatation (FMD) of the brachial and radial arteries is an important research tool for assessment of endothelial function in vivo, and is nitric oxide (NO) dependent. The leg skeletal muscle vascular bed is an important territory for studies in exercise physiology. However, the role of endothelial NO in the FMD response of lower limb arteries has never been investigated. The purpose of this study was to examine the contribution of NO to FMD in the superficial femoral artery in healthy subjects. Since physical inactivity may affect endothelial function, and therefore NO availability, spinal cord-injured (SCI) individuals were included as a model of extreme deconditioning. In eight healthy men (34 +/- 13 years) and six SCI individuals (37 +/- 10 years), the 5 min FMD response in the superficial femoral artery was assessed by echo-Doppler, both during infusion of saline and during infusion of the NO synthase blocker N(G)-monomethyl-L-arginine (L-NMMA). In a subset of the controls (n = 6), the 10 min FMD response was also examined using the same procedure. The 5 min FMD response in controls (4.2 +/- 0.3%) was significantly diminished during L-NMMA infusion (1.0 +/- 0.2%, P < 0.001). In SCI, L-NMMA also significantly decreased the FMD response (from 8.2 +/- 0.4% during saline to 2.4 +/- 0.5% during L-NMMA infusion). The hyperaemic flow response during the first 45 s after cuff deflation was lower in both groups during infusion of L-NMMA, but the effect of L-NMMA on FMD persisted in both groups after correction for the shear stress stimulus. The 10 min FMD was not affected by L-NMMA (saline: 5.4 +/- 1.6%, L-NMMA: 5.6 +/- 1.5%). Superficial femoral artery FMD in response to distal arterial occlusion for a period of 5 min is predominantly mediated by NO in healthy men and in the extremely deconditioned legs of SCI individuals.

Postimpoundment time course of increased mercury concentrations in fish in hydroelectric reservoirs of northern Manitoba, Canada

Mercury (Hg) concentrations in fish in boreal reservoirs have been shown to be increased for up to 3 decades after impoundment. However, the time course of increased concentrations is not well known. The purpose of this study was to determine the evolution of Hg concentrations in fish in the boreal reservoirs of northern Manitoba, Canada, and its relationship with severity of flooding. We determined total Hg concentrations in three species of fish for up to 35 years after impoundment in 14 lakes and lake basins. Postimpoundment trends depended on fish species and reservoir. In the benthivorous lake whitefish (Coregonus clupeaformis), Hg concentrations increased after flooding to between 0.2 and 0.4 microg g(-1) wet weight compared with preimpoundment concentrations between 0.06 and 0.14 microg g(-1) and concentrations in natural lakes between 0.03 and 0.06 microg g(-1). Hg concentrations in lake whitefish were usually highest within 6 years after lake impoundment and took 10 to 20 years after impoundment to decrease to background concentrations in most reservoirs. Hg concentrations in predatory northern pike (Esox lucius) and walleye (Sander vitreus) were highest 2 to 8 years after flooding at 0.7 to 2.6 microg g(-1) compared with preimpoundment concentrations of 0.19 to 0.47 microg g(-1) and concentrations in natural lakes of 0.35 to 0.47 microg g(-1). Hg concentrations in these predatory species decreased consistently in subsequent years and required 10 to 23 years to return to background levels. Thus, results demonstrate the effect of trophic level on Hg concentrations (biomagnification). Peak Hg concentrations depended on the amount of flooding (relative increase in lake surface area). Asymptotic concentrations of approximately 0.25 microg g(-1) for lake whitefish and 1.6 microg g(-1) for both walleye and northern pike were reached at approximately 100% flooding. Downstream effects were apparent because many reservoirs downstream of other impoundments had higher Hg concentrations in fish than would be expected on the basis of flooding amount.

Cross calibration of Hologic QDR2000 and GE Lunar Prodigy for forearm bone mineral density measurements

The purpose of this study was to carry out an in vivo cross calibration for forearm bone mineral density (BMD) between a Hologic QDR2000 (Hologic Inc., Bedford MA, USA) and Lunar Prodigy (GE Healthcare, Madison WI, USA) during equipment upgrade. Nineteen subjects (17 females and 2 males, mean age 57 yr, range: 42-79yr) attending for routine dual energy X-ray absorptiometry scanning were recruited. BMD of the nondominant forearm was measured on both instruments. Cross-calibration equations were derived for total forearm, ultradistal radius and ulna, and 33% radius and ulna. A Bland & Altman plot was used to calculate the mean difference and limits of agreement between instruments. There were significant differences in BMD at all sites. The Prodigy BMD was 15% higher at the total forearm and 20-25% higher in the cortical regions of the 33% ulna and 33% radius. The differences are smaller in the ultradistal regions, as it appears that the Prodigy underestimates BMD at low BMD. The standard error of estimate about the cross calibration was such that it cannot be used to transfer individual patients between instruments, but could be applied to clinical trial data.

Limb-size proportions in Australopithecus afarensis and Australopithecus africanus

Previous analyses have suggested that Australopithecus africanus possessed more apelike limb proportions than Australopithecus afarensis. However, due to the errors involved in estimating limb length and body size, support for this conclusion has been limited. In this study, we use a new Monte Carlo method to (1) test the hypothesis that A. africanus had greater upper:lower limb-size proportions than A. afarensis and (2) assess the statistical significance of interspecific differences among these taxa, extant apes, and humans. Our Monte Carlo method imposes sampling constraints that reduce extant ape and human postcranial measurements to sample sizes comparable to the fossil samples. Next, composite ratios of fore- and hindlimb geometric means are calculated for resampled measurements from the fossils and comparative taxa. Mean composite ratios are statistically indistinguishable (alpha=0.05) from the actual ratios of extant individuals, indicating that this method conserves each sample's central tendency. When applied to the fossil samples, upper:lower limb-size proportions in A. afarensis are similar to those of humans (p=0.878) and are significantly different from all great ape proportions (p< or =0.034), while Australopithecus africanus is more similar to the apes (p> or =0.180) and significantly different from humans and A. afarensis (p< or =0.031). These results strongly support the hypothesis that A. africanus possessed more apelike limb-size proportions than A. afarensis, suggesting that A. africanus either evolved from a more postcranially primitive ancestor than A. afarensis or that the more apelike limb-size proportions of A. africanus were secondarily derived from an A. afarensis-like ancestor. Among the extant taxa, limb-size proportions correspond with observed levels of forelimb- and hindlimb-dominated positional behaviors. In conjunction with detailed anatomical features linked to arboreality, these results suggest that arboreal posture and locomotion may have been more important components of the A. africanus behavioral repertoire relative to that of A. afarensis.

The multiple signals assessed by female satin bowerbirds: could they be used to narrow down females' choices of mates?

Female choice based on multiple male traits has been documented in many species but the functions of such multiple traits are still under debate. The satin bowerbird has a polygynous mating system in which males attract females to bowers for mating; females choose mates based on multiple aspects of males and their bowers. In this paper, we demonstrate that females use some cues to decide which males to examine closely and other cues to decide which males to mate with. Female visitation rates to bowers were significantly related to male size and the males' 'solitary' display rates, and, to a lesser extent, to the numbers of bower decorations. After controlling for female visitation rates, it was found that a male's mating success was significantly related to his size and the rate at which he 'painted' his bower with saliva and chewed up plant material.

Tactical Surgical Intervention With Temporary Shunting of Peripheral Vascular Trauma Sustained During Operation Iraqi Freedom: One Unit??s Experience

BACKGROUND

Rapidly restoring perfusion to injured extremities is one of the primary missions of forward military surgical teams. The austere setting, limited resources, and grossly contaminated nature of wounds encountered complicates early definitive repair of complex combat vascular injuries. Temporary vascular shunting of these injuries in the forward area facilitates rapid restoration of perfusion while allowing for deferment of definitive repair until after transport to units with greater resources and expertise.

METHODS

Standard Javid or Sundt shunts were placed to temporarily bypass complex peripheral vascular injuries encountered by a forward US Navy surgical unit during a six month interval of Operation Iraqi Freedom. Data from the time of injury through transfer out of Iraq were prospectively recorded. Each patient's subsequent course at Continental US medical centers was retrospectively reviewed once the operating surgeons had returned from deployment.

RESULTS

Twenty-seven vascular shunts were used to bypass complex vascular injuries in twenty combat casualties with a mean injury severity score of 18 (range 9-34) and mean mangled extremity severity score of 9 (range 6-11). All patients survived although three (15%) ultimately required amputation for nonvascular complications. Six (22%) shunts clotted during transport but an effective perfusion window was provided even in these cases.

CONCLUSION

Temporary vascular shunting appears to provide simple and effective means of restoring limb perfusion to combat casualties at the forward level.

High-intensity inspiratory muscle training in COPD

The aim of the present study was to investigate the effects of an interval-based high-intensity inspiratory muscle training (H-IMT) programme on inspiratory muscle function, exercise capacity, dyspnoea and health-related quality of life (QoL) in subjects with chronic obstructive pulmonary disease. A double-blind randomised controlled trial was performed. Sixteen subjects (11 males, mean forced expiratory volume in one second (FEV(1)) 37.4+/-12.5%) underwent H-IMT performed at the highest tolerable inspiratory threshold load (increasing to 101% of baseline maximum inspiratory pressure). Seventeen subjects (11 males, mean FEV(1 )36.5+/-11.5%) underwent sham inspiratory muscle training (S-IMT) at 10% of maximum inspiratory pressure. Training took place three times a week for 8 weeks and was fully supervised. Pre- and post-training measurements of lung function, maximum inspiratory pressure, maximum threshold pressure, exercise capacity, dyspnoea and QoL (Chronic Respiratory Disease Questionnaire; CRDQ) were obtained. H-IMT increased maximum inspiratory pressure by 29%, maximum threshold pressure by 56%, 6-min walk distance by 27 m, and improved dyspnoea and fatigue (CRDQ) by 1.4 and 0.9 points per item, respectively. These changes were significantly greater than any seen following S-IMT. In conclusion, high-intensity inspiratory muscle training improves inspiratory muscle function in subjects with moderate-to-severe chronic obstructive pulmonary disease, yielding meaningful reductions in dyspnoea and fatigue.

The Experience of the US Marine Corps?? Surgical Shock Trauma Platoon With 417 Operative Combat Casualties During a 12 Month Period of Operation Iraqi Freedom

BACKGROUND

The Forward Resuscitative Surgical System (FRSS) is a small, mobile trauma surgical unit designed to support modern US Marine Corps combat operations. The experience of two co-located FRSS teams during 1 year of service in Operation Iraqi Freedom is reviewed to evaluate the system's efficacy.

METHODS

Between March 1, 2004, and February 28, 2005, two FRSS teams and a shock trauma platoon were co-located in a unit designated the Surgical Shock Trauma Platoon (SSTP). Data concerning patient care before and during treatment at the SSTP was maintained prospectively. Prospective determination of outcomes was obtained by e-mail correspondence with surgeons caring for the patients at higher echelons. The Los Angeles County medical center (LAC) trauma registry was queried to obtain a comparable data-base with which to compare outcomes.

RESULTS

During the year reviewed there were 895 trauma admissions to the SSTP. Excluding 25 patients pulseless on arrival and 291 minimally injured patients, 559 of 579 (97%) combat casualties survived; 417 casualties underwent 981 operative procedures in the two SSTP operating shelters. There were 79 operative patients with a mean injury severity score of 26 (range, 16-59) and mean revised trauma score of 6.963 (range, 4.21-7.841) who had sustained severe injuries. Ten (12.7%) of these casualties died while 43 of 337 (12.8%) deaths were seen with comparable cases treated at LAC.

CONCLUSIONS

Small task-oriented surgical units are capable of providing effective trauma surgical care to combat casualties. Further experience is needed to better delineate the balance between early, forward-based surgical intervention and more prolonged initial casualty evacuation to reach more robust surgical facilities.

Abnormal ventilatory responses to hypoxia in Type 2 diabetes

AIMS

The incidence of Type 2 diabetes is increasing, along with its associated micro- and macrovascular disease manifestations. Previous studies indicate that patients with Type 2 diabetes exhibit abnormal cardiopulmonary reflex responses to various stimuli, although the impact of hypoxia, a common physiological stimulus, on ventilatory responses has not previously been studied in humans with Type 2 diabetes.

METHODS

Minute ventilation (V(E)) breathing pattern responses (total breath time, T(TOT); expiratory time, T(E); inspiratory time, T(I); inspiratory duty cycle, T(I)/T(TOT)) were measured during 5 min each of normoxia and isocapnic hypoxia (arterial O2 saturation approximately 85%) in eight subjects with Type 2 diabetes and seven age- and body mass index-matched healthy subjects.

RESULTS

During normoxia, V(E) was similar in control and diabetic subjects (6.4+/-1.2, 6.4+/-1.1 l/min, respectively). In response to hypoxia, V(E) significantly increased in both groups (to 17.0+/-5.0 and 9.5+/-2.0 l/min, respectively, P<0.05), but the magnitude of increase in V(E) was significantly less in diabetic than in control subjects (P<0.05). In addition, the breathing pattern response to hypoxia differed between groups in terms of T(I)/T(TOT) and T(TOT) (P<0.05), with control subjects significantly decreasing T(TOT) and T(E) (P<0.05) while diabetic subjects tended to increase both.

CONCLUSIONS

Relative to matched control subjects, Type 2 diabetic subjects exhibit blunted V(E) responses to acute isocapnic hypoxia, suggesting that this group of diabetic subjects possesses a chemoreflex ill-equipped to respond homeostatically to hypoxic challenge.

Screening for atherosclerosis in patients with rheumatoid arthritis: comparison of two in vivo tests of vascular function

OBJECTIVE

Inflammation appears to play a central role in atherosclerosis, and endothelial damage mediated by systemic inflammation may contribute to the increased cardiovascular mortality in rheumatoid arthritis (RA). Brachial artery flow-mediated dilatation (FMD) and pulse wave analysis (PWA) are measures of vascular function. The aim of this study was to determine if FMD and PWA are abnormal in patients with RA.

METHODS

Twenty-five RA patients and 25 matched healthy controls were studied. All were free of traditional cardiovascular risk factors. FMD was measured in all subjects. PWA was performed in 18 RA patients and 18 controls, with results expressed as large and small artery compliance (C1 and C2). Modified Sharp scores were calculated in 13 RA patients.

RESULTS

Results (mean +/- SD) in RA patients and controls, respectively, were as follows: FMD 107.6 +/- 4.6% versus 108.5 +/- 4.1% (P = 0.49), C1 14.8 +/- 2.8 ml/mm Hg x 10 versus 17.9 +/- 3.1 ml/mm Hg x 10 (P = 0.0033), C2 4.5 +/- 2.3 ml/mm Hg x 100 versus 7.7 +/- 3.7 ml/mm Hg x 100 (P = 0.0039). There was an inverse correlation between C2 and modified Sharp scores in the RA patients (Spearman's rho -0.69, P = 0.0085).

CONCLUSION

FMD was normal in these RA patients, whereas arterial compliance was markedly reduced. PWA appears to be a more sensitive measure of vascular dysfunction than FMD in RA and may be the preferred surrogate marker of vascular dysfunction in longitudinal studies of RA patients. The inverse correlation between C2 and the modified Sharp score, a measure that reflects disease activity over time, supports the notion that chronic inflammation plays a role in RA-associated atherosclerosis.

A comparison of phantoms for cross-calibration of lumbar spine DXA

The aim of this project was to compare three phantoms used for cross-calibration of dual-energy X-ray absorptiometers with an in vivo cross-calibration. The phantoms used were the Bona Fide Phantom (BFP), the European Spine Phantom (ESP) and the GE Lunar Aluminum Spine Phantom (ASP). The cross calibration was for L2-L4 lumbar spine bone mineral density (BMD) on a GE Lunar DPX-L and Hologic QDR 2000. The in vivo cross-calibration was obtained using 72 subjects (61 female, 11 male; mean age 49 years, range 14-84 years). The phantoms were measured 10 times without repositioning on both instruments. A further, long-term cross-calibration was obtained with the BFP over a 9 month period. The true linear relationship between the two instruments was calculated used a standardized principal components method. The mean residuals were calculated between each phantom cross-calibration line and the in vivo data to obtain a measure of the goodness of fit between the phantom cross-calibration and the in vivo data. There was no significant difference between the in vitro and in vivo cross-calibrations. The long-term BFP cross-calibration gave an in vitro cross-calibration that is closest to the in vivo cross-calibration in this group of subjects. When calculating Hologic QDR BMD from results on the GE Lunar DPX-L, the ASP underestimates Hologic QDR 2000 BMD by 4% at high BMD and overestimates by 4% at low BMD. The ESP cross-calibration overestimates Hologic QDR2000 BMD by 1% at high BMD and 4% at low BMD. The BFP performs best, overestimating Hologic QDR2000 BMD by between 1.2% and 1.8%, whilst the difference between the long-term BFP cross-calibration and the in vivo data is less than 1% over the range of BMD covered.

Extra-pair paternity and mate-guarding behaviour in the brown thornbill

We used multilocus DNA fingerprinting to assess parentage in the brown thornbill, Acanthiza pusilla, a socially monogamous Australian passerine. Extra-pair paternity was uncommon (6.2% of 178 offspring; 11.9% of 67 broods) and there was no evidence of intra-specific brood parasitism. Extra-pair paternity was limited because pairs spent more time together when females were fertile and males were able to evict intruding males before they could approach the female. Males were responsible for the close proximity of partners during the fertile period. Mate guarding therefore appears to be a male tactic aimed at preventing female infidelity rather than a cooperative behaviour of the pair aimed at preventing extra-pair copulations and/or female harassment. Females did not attempt to escape male guarding and were rarely observed to solicit copulations from intruding males. Nevertheless, females paired to smaller and younger males were more likely to cuckold their mates than females paired to larger and older males. This suggests that females may be more likely to seek or accept extra-pair matings when paired to small, young males or that old, large males are better at preventing their mates from engaging in extra-pair copulations. We found that male age but not male size influences mate-guarding behaviour. Older males tended to respond more aggressively to intruders. We therefore speculate that the relationship between male size/age and extra-pair paternity in brown thornbills may arise because female thornbills prefer large males as mates but are unable to express this preference as easily when paired to older males.

A comparison of the shuttle and 6 minute walking tests with measured peak oxygen consumption in patients with heart failure

This study investigated the use of an incremental, externally-paced 10 m shuttle walk test (SWT) as an objective, reliable and predictive test of functional capacity in patients with heart failure (CHF). The SWT was compared to a 6 minute walk test (6WT) and a maximal symptom-limited treadmill peak oxygen consumption (VO2peak) test. Experiment 1 examined the reproducibility of the SWT. Two SWF trials were performed and distance ambulated (DA), heart rate (HR) and rate of perceived exertion (RPE) results compared. In experiment 2, SWT, 6WT, and VO2 peak tests were performed and HR. RPE and ambulatory VO2 compared. The SWT demonstrated strong test/retest reliability for DA (r = 0.98). HR (r = 0.96) and RPE (r = 0.89). Treadmill VO2 peak was significantly correlated with DA during the SWT (r = 0.83, P < 0.05), but not the 6WT. SWT peak VO2 (18.5 +/- 1.8 ml.kg(-1) x min(-1)) and treadmill VO2 peak (18.3 +/-2.0 ml.kg(-1) x min(-1)) were also highly correlated (r = 0.78, P < 0.05). Conversely, 6WT peak VO2 and treadmill VO2 peak were not significantly correlated. This study suggests the SWT is a reliable, objective test, highly predictive of VO2 peak which may be a more optimal field exercise test than the self paced 6WT.

A comparison of ambulatory oxygen consumption during circuit training and aerobic exercise in patients with chronic heart failure

PURPOSE

This study compared the exercise intensity of a combined aerobic and resistance exercise circuit training session with the exercise intensity of continuous aerobic exercise in patients with chronic heart failure (CHF).

METHODS

Peak oxygen consumption (VO2peak) and muscular strength (1 repetition maximum) were assessed in six CHF patients (age 62 +/- 3 years). Heart rate, rate of perceived exertion (RPE), blood pressures, ambulatory oxygen consumption (VO2), and ventilatory data were measured during two types of exercise: continuous cycling on a bicycle ergometer (aerobic [AER] session) and combined AER and resistance exercise (circuit training [CIR] session).

RESULTS

There were no significant differences in VO2, RPE, heart rate, or hemodynamic responses (rate pressure product, diastolic blood pressure, or mean arterial pressure) during exercise, between the two sessions. Systolic blood pressure was significantly lower during CIR (P < 0.05). Minute ventilation and tidal volume were significantly higher (P < 0.0001 and P < 0.01, respectively) and respiratory frequency significantly lower (P < 0.005) during CIR. During CIR, RPE significantly correlated with VO2 (P < 0.01), whereas heart rate did not. Conversely, during the AER session HR correlated with VO2 (P < 0.01), but RPE did not.

CONCLUSIONS

Circuit training is a well-tolerated form of exercise training for CHF patients that is associated with similar oxygen and hemodynamic demand to aerobic exercise. Results suggest that RPE may be a better method of prescribing and monitoring exercise intensity during CIR, with heart rate the preferred measure of intensity during aerobic exercise.

Closed pelvic fractures: characteristics and outcomes in older patients admitted to medical and geriatric wards

OBJECTIVE

To investigate the characteristics and outcomes of older patients with pelvic fracture admitted to medical and geriatric wards.

METHODS

All patients admitted to medical and geriatric wards with a pelvic fracture over a four year period were identified using the hospital clinical coding database. Data were collected from casenotes, hospital and Family Health Services Authority databases. Where available, pelvic radiographs were graded according to the Singh index.

RESULTS

The casenotes of 148 patients (126 women) were studied; 83% (n=123) of patients suffered a pelvic fracture in low energy trauma. Mean (SD) length of hospital stay was 21.3 (17.6) days. Single breaks of the pubic rami accounted for 47.2% (n=68) of all fractures. Inpatient mortality was 7.6% and at one year was 27%. There was a marked adverse effect on the mobility of survivors with all patients using at least a walking stick at discharge and 51.1% (n=70) needing assistance for mobility. Although 70.9% (n=83) of patients admitted from home (or warden aided accommodation) were able to return there, 84.3% (n=70) of them required extra community support. Rates of institutionalisation rose from 20.9% (n=31) at admission to 35.8% (49/137) of survivors at discharge. Altogether 93% (n=107) of 115 patients, in whom adequate quality pelvic radiographs were available, were assigned a Singh index grade of 4 or less indicating the presence of osteoporosis.

CONCLUSIONS

Pelvic fractures are often the result of low energy trauma. They are associated with appreciable inpatient and considerable one year mortality. They also have marked negative effects on mobility in the short term. They result in increased levels of dependency in terms of higher levels of community support and rates of institutionalisation. On the evidence of Singh index grading, pelvic fractures are associated with low bone density.