Dissecting Carotenoid from Structural Components of Carotenoid-Based Coloration: A Field Experiment with Great Tits (Parus major)

Carotenoid-based yellowish to red plumage colors are widespread visual signals used in sexual and social communication. To understand their ultimate signaling functions, it is important to identify the proximate mechanism promoting variation in coloration. Carotenoid-based colors combine structural and pigmentary components, but the importance of the contribution of structural components to variation in pigment-based colors (i.e., carotenoid-based colors) has been undervalued. In a field experiment with great tits (Parus major), we combined a brood size manipulation with a simultaneous carotenoid supplementation in order to disentangle the effects of carotenoid availability and early growth condition on different components of the yellow breast feathers. By defining independent measures of feather carotenoid content (absolute carotenoid chroma) and background structure (background reflectance), we demonstrate that environmental factors experienced during the nestling period, namely, early growth conditions and carotenoid availability, contribute independently to variation in yellow plumage coloration. While early growth conditions affected the background reflectance of the plumage, the availability of carotenoids affected the absolute carotenoid chroma, the peak of maximum ultraviolet reflectance, and the overall shape, that is, chromatic information of the reflectance curves. These findings demonstrate that environment-induced variation in background structure contributes significantly to intraspecific variation in yellow carotenoid-based plumage coloration.

Immune Activation Reduces Sperm Quality in the Great Tit

Mounting an immune response against pathogens incurs costs to organisms by its effects on important life-history traits, such as reproductive investment and survival. As shown recently, immune activation produces large amounts of reactive species and is suggested to induce oxidative stress. Sperm are highly susceptible to oxidative stress, which can negatively impact sperm function and ultimately male fertilizing efficiency. Here we address the question as to whether mounting an immune response affects sperm quality through the damaging effects of oxidative stress. It has been demonstrated recently in birds that carotenoid-based ornaments can be reliable signals of a male's ability to protect sperm from oxidative damage. In a full-factorial design, we immune-challenged great tit males while simultaneously increasing their vitamin E availability, and assessed the effect on sperm quality and oxidative damage. We conducted this experiment in a natural population and tested the males' response to the experimental treatment in relation to their carotenoid-based breast coloration, a condition-dependent trait. Immune activation induced a steeper decline in sperm swimming velocity, thus highlighting the potential costs of an induced immune response on sperm competitive ability and fertilizing efficiency. We found sperm oxidative damage to be negatively correlated with sperm swimming velocity. However, blood resistance to a free-radical attack (a measure of somatic antioxidant capacity) as well as plasma and sperm levels of oxidative damage (lipid peroxidation) remained unaffected, thus suggesting that the observed effect did not arise through oxidative stress. Towards the end of their breeding cycle, swimming velocity of sperm of more intensely colored males was higher, which has important implications for the evolution of mate choice and multiple mating in females because females may accrue both direct and indirect benefits by mating with males having better quality sperm.

Echocardiogram versus cardiac magnetic resonance imaging for assessing systolic function of subaortic right ventricle in adults with complete transposition of great arteries and previous atrial switch operation

In adults with congenital heart disease and a systemic right ventricle, subaortic ventricular systolic dysfunction is common. Echocardiographic assessment of systolic right ventricular (RV) function in these patients is important but challenging. The aim of the present study was to assess the reliability of conventional echocardiographic RV functional parameters to quantify the systolic performance of a subaortic right ventricle. We compared 56 contemporary echocardiograms and cardiac magnetic resonance studies in 37 adults, aged 26.9 ± 7.4 years, with complete transposition and a subaortic right ventricle. The fractional area change (FAC), lateral tricuspid annular plane systolic excursion, lateral RV systolic motion velocities by tissue Doppler, RV myocardial performance index, and the rate of systolic RV pressure increase (dp/dt) measured across the tricuspid regurgitant jet were assessed by echocardiography and correlated with the cardiac magnetic resonance-derived RV ejection fraction (EF). The mean RVEF was 48.0 ± 7.8%. FAC (r(2) = 0.206, p = 0.001) and dp/dt (r(2) = 0.173, p = 0.009) significantly correlated with RVEF, and the other nongeometric echocardiographic parameters failed to show a significant correlation with RVEF by linear regression analysis. FAC <33% and dp/dt <1,000 mm Hg/s identified a RVEF of <50% with a sensitivity of 77% and 69% and a specificity of 58% and 87%, respectively. In conclusion, in patients with a systemic right ventricle, routine nongeometric echocardiographic parameters of RV function correlated weakly with cardiac magnetic resonance-derived EF. RV FAC and the measurement of the rate of systolic RV pressure increase (dp/dt) should be preferentially used to assess systemic systolic function in adult patients with a subaortic right ventricle.

Outcome in adult patients after arterial switch operation for transposition of the great arteries

BACKGROUND: The arterial switch operation (ASO) is currently the treatment of choice in neonates with transposition of the great arteries (TGA). The outcome in childhood is encouraging but only limited data for long-term outcome into adulthood exist. METHODS AND RESULTS: We studied 145 adult patients (age>16, median 25years) with ASO followed at our institution. Three patients died in adulthood (mortality 2.4/1000-patient-years). Most patients were asymptomatic and had normal left ventricular function. Coronary lesions requiring interventions were rare (3 patients) and in most patients related to previous surgery. There were no acute coronary syndromes. Aortic root dilatation was frequent (56% patients) but rarely significant (>45mm in 3 patients, maximal-diameter 49mm) and appeared not to be progressive. There were no acute aortic events and no patient required elective aortic root surgery. Progressive neo-aortic-valve dysfunction was not observed in our cohort and only 1 patient required neo-aortic-valve replacement. Many patients (42.1%), however, had significant residual lesions or required reintervention in adulthood. Right ventricular outflow tract lesions or dysfunction of the neo-pulmonary-valve were frequent and 8 patients (6%) required neo-pulmonary-valve replacement. Cardiac interventions during childhood (OR 3.0, 95% CI 1.7-5.4, P<0.0001) were strong predictors of outcome (cardiac intervention/significant residual lesion/death) in adulthood. CONCLUSIONS: Adult patients with previous ASO remain free of acute coronary or aortic complications and have low mortality. However, a large proportion of patients require re-interventions or present with significant right sided lesions. Life-long cardiac follow-up is, therefore, warranted. Periodic noninvasive surveillance for coronary complications appears to be safe in adult ASO patients.

Immunocompetence of nestling great tits in relation to rearing environment and parentage

Theoretical models of host-parasite coevolution assume a partially genetic basis to the variability in susceptibility to parasites among hosts, for instance as a result of genetic variation in immune function. However, few empirical data exist for free-living vertebrate hosts to support this presumption. In a cross-fostering experiment with nestling great tits, by comparing nestlings of the same origin we investigated (i) the variance in host resistance against an ectoparasite due to a common genetic origin, (ii) the effect of ectoparasite infestation on cell-mediated immunity and (iii) the variance in cell-mediated immunity due to a common genetic origin. Ectoparasitic hen fleas can impair the growth of nestling great tits and nestling growth was therefore taken as a measure of host susceptibility. A common origin did not account for a significant part of the variation in host susceptibility to fleas. There was no significant overall effect of fleas on nestling growth or cell-mediated immunity, as assessed by a cutaneous hypersensitivity response. A common rearing environment explained a significant part of the variation in cell-mediated immunity among nestlings, mainly through its effect on nestling body mass. The variation in cell-mediated immunity was also related to a common origin. However, the origin-related variation in body mass did not account for the origin-related differences in cell-mediated immunity. The results of the present study thus suggest heritable variation in cell-mediated immunity among nestling great tits. [References: 49]

The arterial switch operation in Europe for transposition of the great arteries: a multi-institutional study from the European Congenital Heart Surgeons Association

OBJECTIVES: This study analyzes the results of the arterial switch operation for transposition of the great arteries in member institutions of the European Congenital Heart Surgeons Association. METHODS: The records of 613 patients who underwent primary arterial switch operations in each of 19 participating institutions in the period from January 1998 through December 2000 were reviewed retrospectively. RESULTS: A ventricular septal defect was present in 186 (30%) patients. Coronary anatomy was type A in 69% of the patients, and aortic arch pathology was present in 20% of patients with ventricular septal defect. Rashkind septostomy was performed in 75% of the patients, and 69% received prostaglandin. There were 37 hospital deaths (operative mortality, 6%), 13 (3%) for patients with an intact ventricular septum and 24 (13%) for those with a ventricular septal defect (P < .001). In 36% delayed sternal closure was performed, 8% required peritoneal dialysis, and 2% required mechanical circulatory support. Median ventilation time was 58 hours, and intensive care and hospital stay were 6 and 14 days, respectively. Although of various preoperative risk factors the presence of a ventricular septal defect, arch pathology, and coronary anomalies were univariate predictors of operative mortality, only the presence of a ventricular septal defect approached statistical significance (P = .06) on multivariable analysis. Of various operative parameters, aortic crossclamp time and delayed sternal closure were also univariate predictors; however, only the latter was an independent statistically significant predictor of death. CONCLUSIONS: Results of the procedure in European centers are compatible with those in the literature. The presence of a ventricular septal defect is the clinically most important preoperative risk factor for operative death, approaching statistical significance on multivariable analysis.