Cardiovascular risk and mortality in patients with hyperuricemia treated with febuxostat or allopurinol: a retrospective nation-wide cohort study in Austria 2014-2017.

Patients with hyperuricemia and gout are at an increased risk for cardiovascular (CV) disease. Inhibition of the xanthine oxidase with allopurinol or febuxostat have become the mainstay for urate lowering therapy. However, it has been suggested that febuxostat increases the risk for CV mortality as compared to allopurinol. The aim of this retrospective cohort study was to assess the CV risk among patients with febuxostat or allopurinol therapy. Patients who initiated urate lowering therapy with febuxostat or allopurinol between 2014 and 2017 were selected from the drug reimbursement database of the Austrian health insurances funds. The primary CV endpoint was a composite of angina pectoris, nonfatal myocardial infarction, nonfatal subarachnoid or cerebral hemorrhage, nonfatal ischemic stroke, or death from any cause. In total, 28.068 patients (62.1% male) with a mean age of 71 years were included. 7.767 initiated febuxostat treatment and 20.301 received allopurinol. The incidence rate per 100 patient-years of the composite primary endpoint was 448 (febuxostat) and 356 (allopurinol) with a corresponding adjusted hazard ratio (HR) of 0.58 (95% CI 0.53-0.63) for allopurinol vs. febuxostat initiators. Similar HR were found for secondary endpoints including all-cause mortality [0.61 (95% CI 0.55-0.68)] and separate analyses of cardiac events [0.48 (95% CI 0.38-0.61)] and ischemic stroke [0.47 (95% CI 0.36-0.61)]. Data from this Austrian population-based study suggests that febuxostat initiators are at an increased risk for nonfatal CV events or death from any cause as compared to those with allopurinol. This is consistent with CV concerns of other trials, which limited the broad therapeutic use of febuxostat.

Lombard effect onset times reveal the speed of vocal plasticity in a songbird.

Animals that use vocal signals to communicate often compensate for interference and masking from background noise by raising the amplitude of their vocalisations. This response has been termed the Lombard effect. However, despite more than a century of research, little is known how quickly animals can adjust the amplitude of their vocalisations after the onset of noise. The ability to respond quickly to increases in noise levels would allow animals to avoid signal masking and ensure their calls continue to be heard, even if they are interrupted by sudden bursts of high-amplitude noise. We tested how quickly singing male canaries (Serinus canaria) exhibit the Lombard effect by exposing them to short playbacks of white noise and measuring the speed of their responses. We show that canaries exhibit the Lombard effect in as little as 300 ms after the onset of noise and are also able to increase the amplitude of their songs mid-song and mid-phrase without pausing. Our results demonstrate high vocal plasticity in this species and suggest that birds are able to adjust the amplitude of their vocalisations very rapidly to ensure they can still be heard even during sudden changes in background noise levels.

Hatching late in the season requires flexibility in the timing of song learning.

Most songbirds learn their songs from adult tutors, who can be their father or other male conspecifics. However, the variables that control song learning in a natural social context are largely unknown. We investigated whether the time of hatching of male domesticated canaries has an impact on their song development and on the neuroendocrine parameters of the song control system. Average age difference between early- and late-hatched males was 50 days with a maximum of 90 days. Song activity of adult tutor males decreased significantly during the breeding season. While early-hatched males were exposed to tutor songs for on average the first 99 days, late-hatched peers heard adult song only during the first 48 days of life. Remarkably, although hatching late in the season negatively affected body condition, no differences between both groups of males were found in song characteristics either in autumn or in the following spring. Similarly, hatching date had no effect on song nucleus size and circulating testosterone levels. Our data suggest that late-hatched males must have undergone accelerated song development. Furthermore, the limited tutor song exposure did not affect adult song organization and song performance.

Breeding status and social environment differentially affect the expression of sex steroid receptor and aromatase mRNA in the brain of female Damaraland mole-rats.

INTRODUCTION: The Damaraland mole-rat (Fukomys damarensis) is a eusocial, subterranean mammal, which exhibits an extreme reproductive skew with a single female (queen) monopolizing reproduction in each colony. Non-reproductive females in the presence of the queen are physiologically suppressed to the extent that they are anovulatory. This blockade is thought to be caused by a disruption in the normal gonadotropin-releasing hormone (GnRH) secretion from the hypothalamus. In order to understand the underlying physiological mechanisms of reproductive suppression in subordinate females we studied the expression of steroid hormone receptors and the androgen-converting enzyme aromatase in forebrain regions involved in the control of reproductive behaviour in female breeders and non-breeders from intact colonies. Additionally, we included in our analysis females that experienced the release from social suppression by being removed from the presence of the queen. RESULTS: We found expression of androgen receptor, estrogen receptor α and aromatase in several forebrain regions of female Damaraland mole-rats. Their distribution matches previous findings in other mammals. Quantification of the hybridisation signal revealed that queens had increased expression of androgen receptors compared to non-breeders and removed non-breeders in most brain regions examined, which include the medial preoptic area (MPOA), the principal nucleus of the bed nucleus of the stria terminalis (BSTp), the ventromedial nucleus of the hypothalamus (VMH), the arcuate nucleus (ARC) and the medial amygdala (MeA). Furthermore, breeders had increased estrogen receptor α expression in the anteroventral periventricular nucleus (AVPV) and in the MeA, while aromatase expression in the AVPV was significantly reduced compared to non-breeders. Absence of social suppression was associated with increased androgen receptor expression in the ARC, increased estrogen receptor α expression in the MeA and BSTp and reduced aromatase expression in the AVPV. CONCLUSION: This study shows that social suppression and breeding differentially affect the neuroendocrine phenotype of female Damaraland mole-rats. The differential expression pattern of estrogen receptor α and aromatase in the AVPV between breeders and non-breeders supports the view that this region plays an important role in mediating the physiological suppression in subordinate females.

Testosterone-dependency of male solo song in a duetting songbird--evidence from females.

For male songbirds of the temperate zone there is a tight link between seasonal song behaviour and circulating testosterone levels. Such a relationship does not seem to hold for tropical species where singing can occur year-round and breeding seasons are often extended. White-browed sparrow weavers (Plocepasser mahali) are cooperatively breeding songbirds with a dominant breeding pair and male and female subordinates found in eastern and southern Africa. Each group defends an all-purpose territory year-round. While all group members sing duets and choruses, the most dominant male additionally sings a solo song that comprises a distinct and large syllable repertoire. Previous studies suggested this type of song being associated with reproduction but failed to support a relationship with males' circulating testosterone levels. The present study aimed to investigate the steroid hormone sensitivity of the solo song in more detail. We found that dominant males had significantly higher circulating testosterone levels than subordinates during the early and late breeding seasons. No changes in solo song characteristics were found between both time points. Further, experimental implantation of captive adult females with exogenous testosterone induced solo singing within one week of treatment. Such females produced male-typical song regarding overall structure and syllable composition. Sex differences existed, however, concerning singing activity, repertoire size and temporal organisation of song. These results suggest that solo singing in white-browed sparrow weavers is under the control of gonadal steroid hormones. Moreover, the behaviour is not male-specific but can be activated in females under certain conditions.

Extensive GJD2 Expression in the Song Motor Pathway Reveals the Extent of Electrical Synapses in the Songbird Brain.

Birdsong is a precisely timed animal behavior. The connectivity of song premotor neural networks has been proposed to underlie the temporal patterns of neuronal activity that control vocal muscle movements during singing. Although the connectivity of premotor nuclei via chemical synapses has been characterized, electrical synapses and their molecular identity remain unexplored. We show with in situ hybridizations that GJD2 mRNA, coding for the major channel-forming electrical synapse protein in mammals, connexin 36, is expressed in the two nuclei that control song production, HVC and RA from canaries and zebra finches. In canaries' HVC, GJD2 mRNA is extensively expressed in GABAergic and only a fraction of glutamatergic cells. By contrast, in RA, GJD2 mRNA expression is widespread in glutamatergic and GABAergic neurons. Remarkably, GJD2 expression is similar in song nuclei and their respective embedding brain regions, revealing the widespread expression of GJD2 in the avian brain. Inspection of a single-cell sequencing database from zebra and Bengalese finches generalizes the distributions of electrical synapses across cell types and song nuclei that we found in HVC and RA from canaries, reveals a differential GJD2 mRNA expression in HVC glutamatergic subtypes and its transient increase along the neurogenic lineage. We propose that songbirds are a suitable model to investigate the contribution of electrical synapses to motor skill learning and production.

Song learning in domesticated canaries in a restricted acoustic environment.

Many songbirds learn their songs early in life from a song model. In the absence of such a model, they develop an improvised song that often lacks the species-typical song structure. Open-ended learners, such as the domesticated canary, are able to modify their songs in adulthood, although the mechanisms that guide and time the song-learning process are still not fully understood. In a previous study, we showed that male domesticated canaries lacking an adult song model in their first year substantially change their song repertoire and composition when exposed to normally reared conspecifics in their second year. Here, we investigate song development in descendants of canaries that were raised and kept as a peer group without a song model. Such males represent tutors with abnormal song characteristics. Interestingly, the F(1) generation developed quite normal song structure, and when brought into an environment with normally raised canaries in their second year, they did not modify their songs substantially. These results suggest that contact with an adult song model early in life is crucial for song crystallization, but also that song development is at least partly guided by innate rules. They also question the existing classification of canaries as open-ended learners.

Accelerated redevelopment of vocal skills is preceded by lasting reorganization of the song motor circuitry.

Complex motor skills take considerable time and practice to learn. Without continued practice the level of skill performance quickly degrades, posing a problem for the timely utilization of skilled motor behaviors. Here we quantified the recurring development of vocal motor skills and the accompanying changes in synaptic connectivity in the brain of a songbird, while manipulating skill performance by consecutively administrating and withdrawing testosterone. We demonstrate that a songbird with prior singing experience can significantly accelerate the re-acquisition of vocal performance. We further demonstrate that an increase in vocal performance is accompanied by a pronounced synaptic pruning in the forebrain vocal motor area HVC, a reduction that is not reversed when birds stop singing. These results provide evidence that lasting synaptic changes in the motor circuitry are associated with the savings of motor skills, enabling a rapid recovery of motor performance under environmental time constraints.

Duets recorded in the wild reveal that interindividually coordinated motor control enables cooperative behavior.

Many organisms coordinate rhythmic motor actions with those of a partner to generate cooperative social behavior such as duet singing. The neural mechanisms that enable rhythmic interindividual coordination of motor actions are unknown. Here we investigate the neural basis of vocal duetting behavior by using an approach that enables simultaneous recordings of individual vocalizations and multiunit vocal premotor activity in songbird pairs ranging freely in their natural habitat. We find that in the duet-initiating bird, the onset of the partner's contribution to the duet triggers a change in rhythm in the periodic neural discharges that are exclusively locked to the initiating bird's own vocalizations. The resulting interindividually synchronized neural activity pattern elicits vocalizations that perfectly alternate between partners in the ongoing song. We suggest that rhythmic cooperative behavior requires exact interindividual coordination of premotor neural activity, which might be achieved by integration of sensory information originating from the interacting partner.

Seasonality in song behaviour revisited: seasonal and annual variants and invariants in the song of the domesticated canary (Serinus canaria).

The song of the domesticated canary (Serinus canaria) is one of the most widely used models to study the neural correlates of behavioural plasticity and the mechanisms of female mate choice. However, only few studies have described the song behaviour in detail and monitored their changes throughout the year, and these data are restricted to the "Waterslager" strain. Here, we studied the song characteristics of the male common domesticated canary at different times of the year, the spring breeding and autumnal non-breeding season, and monitored the birds' songs up to the following breeding season. During breeding, males have increased plasma levels of testosterone, and songs are on average longer and consist of fewer non-repeated syllable types compared to the non-breeding season. When subsequent seasons are compared, song duration and the proportion of non-repeated syllable types change seasonally but not across years. Repertoire size remains constant throughout seasons although syllable types are exchanged. Syllable carry-over is significantly higher from one breeding season to the next than between the breeding and non-breeding season. Further, the repertoire of the breeding season contains more potentially sexually attractive syllable types than that of the non-breeding season. These data show that overall song structure is retained throughout the year while seasonality occurs in the temporal pattern and in repertoire composition.

Neural activation following offensive aggression in Japanese quail.

Aggression is a fundamental part of animal social behaviour. In avian species, little is known about its neural representation. In particular, neural activity following offensive aggression has not been studied in detail. Here, we investigated the patterns of brain activation using immediate-early gene (IEG) expression in male Japanese quail that showed pronounced aggressive behaviours during a 30 min male-male interaction and compared them to those of males that did not interact with a conspecific. In aggressive males, we found a massive induction of the IEG ZENK in pallial brain structures such as the intermediate medial mesopallium, the caudomedial mesopallium and the intermediate medial nidopallium. To a lesser extent, activation was observed in subpallial areas such as the nucleus taeniae of the amygdala and in the medial portion of the bed nucleus of the stria terminalis. Our data suggest that the modulation of aggressive behaviour involves the integration of multisensory information.

Socially induced brain differentiation in a cooperatively breeding songbird.

Birds living in social groups establish dominance hierarchies, and taking up the dominant position influences behaviour and physiological parameters. In cooperatively breeding white-browed sparrow weavers (Plocepasser mahali), the transition from subordinate helper to dominant breeder male induces the production of a new type of song. This song contains a large number of new syllables and differs in temporal pattern from duet songs produced by all other group members. Here we show that this change in social status of adult males affects the morphology of a behavioural control circuit, the song control system of songbirds that is composed of large neuron populations. The volume of the song control areas HVC and RA and their gene-expression levels depend on males' social status. Dominant males have several times larger testes than subordinates, which is not reflected in circulating androgen and oestrogen levels. Our findings suggest a remarkable differentiation of adult vertebrate brains in relation to changing social cues.

Bioenergy production and sustainable development: science base for policymaking remains limited.

The possibility of using bioenergy as a climate change mitigation measure has sparked a discussion of whether and how bioenergy production contributes to sustainable development. We undertook a systematic review of the scientific literature to illuminate this relationship and found a limited scientific basis for policymaking. Our results indicate that knowledge on the sustainable development impacts of bioenergy production is concentrated in a few well-studied countries, focuses on environmental and economic impacts, and mostly relates to dedicated agricultural biomass plantations. The scope and methodological approaches in studies differ widely and only a small share of the studies sufficiently reports on context and/or baseline conditions, which makes it difficult to get a general understanding of the attribution of impacts. Nevertheless, we identified regional patterns of positive or negative impacts for all categories - environmental, economic, institutional, social and technological. In general, economic and technological impacts were more frequently reported as positive, while social and environmental impacts were more frequently reported as negative (with the exception of impacts on direct substitution of GHG emission from fossil fuel). More focused and transparent research is needed to validate these patterns and develop a strong science underpinning for establishing policies and governance agreements that prevent/mitigate negative and promote positive impacts from bioenergy production.

Parasites affect song complexity and neural development in a songbird.

There is now considerable evidence that female choice drives the evolution of song complexity in many songbird species. However, the underlying basis for such choice remains controversial. The developmental stress hypothesis suggests that early developmental conditions can mediate adult song complexity by perturbing investment in the underlying brain nuclei during their initial growth. Here, we show that adult male canaries (Serinus canaria), infected with malaria (Plasmodium relictum) as juveniles, develop simpler songs as adults compared to uninfected individuals, and exhibit reduced development of the high vocal centre (HVC) song nucleus in the brain. Our results show how developmental stress not only affects the expression of a sexually selected male trait, but also the structure of the underlying song control pathway in the brain, providing a direct link between brain and behaviour. This novel experimental evidence tests both proximate and ultimate reasons for the evolution of complex songs and supports the Hamilton-Zuk hypothesis of parasite-mediated sexual selection. Together, these results propose how developmental costs may help to explain the evolution of honest advertising in the complex songs of birds.

Using the canary genome to decipher the evolution of hormone-sensitive gene regulation in seasonal singing birds.

BACKGROUND: While the song of all songbirds is controlled by the same neural circuit, the hormone dependence of singing behavior varies greatly between species. For this reason, songbirds are ideal organisms to study ultimate and proximate mechanisms of hormone-dependent behavior and neuronal plasticity. RESULTS: We present the high quality assembly and annotation of a female 1.2-Gbp canary genome. Whole genome alignments between the canary and 13 genomes throughout the bird taxa show a much-conserved synteny, whereas at the single-base resolution there are considerable species differences. These differences impact small sequence motifs like transcription factor binding sites such as estrogen response elements and androgen response elements. To relate these species-specific response elements to the hormone-sensitivity of the canary singing behavior, we identify seasonal testosterone-sensitive transcriptomes of major song-related brain regions, HVC and RA, and find the seasonal gene networks related to neuronal differentiation only in the HVC. Testosterone-sensitive up-regulated gene networks of HVC of singing males concerned neuronal differentiation. Among the testosterone-regulated genes of canary HVC, 20% lack estrogen response elements and 4 to 8% lack androgen response elements in orthologous promoters in the zebra finch. CONCLUSIONS: The canary genome sequence and complementary expression analysis reveal intra-regional evolutionary changes in a multi-regional neural circuit controlling seasonal singing behavior and identify gene evolution related to the hormone-sensitivity of this seasonal singing behavior. Such genes that are testosterone- and estrogen-sensitive specifically in the canary and that are involved in rewiring of neurons might be crucial for seasonal re-differentiation of HVC underlying seasonal song patterning.

Developmental stress selectively affects the song control nucleus HVC in the zebra finch.

Songbirds sing complex songs as a result of evolution through sexual selection. The evolution of such sexually selected traits requires genetic control, as well as selection on their expression. Song is controlled by a discrete neural pathway in the brain, and song complexity has been shown to correlate with the volume of specific song control nuclei. As such, the development of these nuclei, in particular the high vocal centre (HVC), is thought to be the mechanism controlling signal expression indicating male quality. We tested the hypothesis that early developmental stress selectively affects adult HVC size, compared with other brain nuclei. We did this by raising cross-fostered zebra finches (Taeniopygia guttata) under stressed and controlled conditions and determining the effect on adult HVC size. Our results confirm the strong influence of environmental conditions, particularly on HVC development, and therefore on the expression of complex songs. The results also show that both environmental and genetic factors affect the development of several brain nuclei, highlighting the developmental plasticity of the songbird brain. In all, these results explain how the complex song repertoires of songbirds can evolve as honest indicators of male quality.

Song and the song control pathway in the brain can develop independently of exposure to song in the sedge warbler.

Previous studies have shown that female sedge warblers choose to mate with males that have more complex songs, and sexual selection has driven the evolution of both song complexity and the size of the major song control area (HVc) in the brain. In songbirds, learning from conspecifics plays a major role in song development and this study investigates the effects of isolation and exposure to song on song structure and the underlying song control system. Sibling pairs of hand-reared nestling sedge warblers were reared to sexual maturity under two conditions. Siblings in one group were reared individually in acoustic isolation in separate soundproof chambers. In the other group, siblings were reared together in an aviary with playback of recorded songs. The following spring, analysis of songs revealed that siblings reared in acoustic isolation produced normal song structures, including larger syllable repertoires than those exposed to song. We found no significant differences in the volumes of HVc, nucleus robustus archistnatalis, the lateral portion of the magnocellular nucleus and the density of dendritic spines between the two groups. Males exceeded females in all these measures, and also had a larger telencephalon. Our experiments show that complex song, sexual dimorphism in brain structure, and the size of song nuclei can all develop independently of exposure to song. These findings have important implications for how sexual selection can operate upon a complex male trait such as song and how it may also shape the more general evolution of brain structure in songbirds.

Environmental and genetic control of brain and song structure in the zebra finch.

Birdsong is a classic example of a learned trait with cultural inheritance, with selection acting on trait expression. To understand how song responds to selection, it is vital to determine the extent to which variation in song learning and neuroanatomy is attributable to genetic variation, environmental conditions, or their interactions. Using a partial cross fostering design with an experimental stressor, we quantified the heritability of song structure and key brain nuclei in the song control system of the zebra finch and the genotype-by-environment (G × E) interactions. Neuroanatomy and song structure both showed low levels of heritability and are unlikely to be under selection as indicators of genetic quality. HVC, in particular, was almost entirely under environmental control. G × E interaction was important for brain development and may provide a mechanism by which additive genetic variation is maintained, which in turn may promote sexual selection through female choice. Our study suggests that selection may act on the genes determining vocal learning, rather than directly on the underlying neuroanatomy, and emphasizes the fundamental importance of environmental conditions for vocal learning and neural development in songbirds.