Vasopressin affects behavior via its two brain receptors, the vasopressin 1a and vasopressin 1b receptors (Avpr1b). Recent work from our laboratory has shown that disruption of the Avpr1b gene reduces intermale aggression and reduces social motivation. Here, we further characterized the aggressive phenotype in Avpr1b 2/2 (knockout) mice. We tested maternal aggression and predatory behavior. We also analyzed the extent to which food deprivation and competition over food increases intermale aggression. We quantified defensive behavior in Avpr1b 2/2 mice and later tested offensive aggression in these same mice. Our results show that attack behavior toward a conspecific is consistently reduced in Avpr1b 2/2 mice. Predatory behavior is normal, suggesting that the deficit is not because of a global inability to detect and attack stimuli. Food deprivation, competition for food and previous experience increase aggression in both Avpr1b 1/1 and 2/2 mice. However, in these circumstances, the level of aggression seen in knockout mice is still less than that observed in wild-type mice. Defensive avoidance behaviors, such as boxing and fleeing, are largely intact in knockout mice. Avpr1b 2/2 mice do not display as many 'retaliatory' attacks as the Avpr1b 1/1 mice. Interestingly, when territorial aggression was measured following the defensive behavior testing, Avpr1b 2/2 mice typically show less initial aggressive behavior than wildtype mice, but do show a significant increase in aggression with repeated testing. These studies confirm that deficits in aggression in Avpr1b 2/2 mice are limited to aggressive behavior involving the attack of a conspecific. We hypothesize that Avpr1b plays an important role in the central processing that couples the detection and perception of social cues (which appears normal) with the appropriate behavioral response.

This study ascertains the ability of bodyweight blood flow-restricted (BFR) exercise training to promote skeletal muscle adaptations of significance for muscle accretion and metabolism. Six healthy young individuals (three males and three females) performed six weeks of bodyweight BFR training. Each session consisted of five sets of sit-to-stand BFR exercise to volitional failure with 30-second inter-set recovery. Prior to, and at least 72 h after training, muscle biopsies were taken from m. vastus lateralis to assess changes in fibre type-specific cross-sectional area (CSA), satellite cell (SC) and myonuclei content and capillarization, as well as mitochondrial protein expression. Furthermore, magnetic resonance imaging was used to assess changes in whole thigh muscle CSA. Finally, isometric knee extensor muscle strength was evaluated. An increase in knee extensor whole muscle CSA was observed at middle and distal localizations after training (3·2% and 3·5%, respectively) (P<0·05), and a trend was observed towards an increase in type I fibre CSA, whereas muscle strength did not increase. Additionally, the number of SCs and myonuclei associated with type I fibres increased by 65·7% and 20%, respectively (P<0·05). No significant changes were observed in measures of muscle capillarization and mitochondrial proteins. In conclusion, six weeks of bodyweight-based BFR exercise promoted myocellular adaptations related to muscle accretion, but not metabolic properties. Moreover, the study revealed that an appropriate total training volume needs further investigation before recommending bodyweight BFR to patient populations.

AimsTo describe aetiologies and temporal trends in young patients with atrioventricular block (AVB).Methods and resultsWe identified all patients in Denmark, receiving their first pacemaker because of AVB before the age of 50 years between 1996 and 2015. Medical records were reviewed and clinical information and diagnostic work-up results were obtained to evaluate the aetiology. We used Poisson regression testing for temporal trends. One thousand and twenty-seven patients were identified, median age at time of implantation was 38 (interquartile range 25–45) years, 584 (56.9%) were male. The aetiologies were complications to cardiac surgery [n = 157 (15.3%)], congenital AVB [n = 93 (9.0%)], cardioinhibitory reflex [n = 52 (5.0%)], congenital heart disease [n = 43 (4.2%)], complication to radiofrequency ablation [n = 35 (3.4%)], cardiomyopathy [n = 31 (3.0%)], endocarditis [n = 18 (1.7%)], muscular dystrophy [n = 14 (1.4%)], ischaemic heart disease [n = 14 (1.4%)], sarcoidosis [n = 11 (1.1%)], borreliosis [n = 9 (0.9%)], hereditary [n = 6 (0.6%)], side-effect to antiarrhythmics [n = 6 (0.6%)], planned His-ablation [n = 5 (0.5%)], complication to alcohol septal ablation [n = 5 (0.5%)], and other known aetiologies [n = 11 (1.1%)]. The aetiology remained unknown in 517 (50.3%) cases. While the number of patients with unknown aetiology increased during the study period (P < 0.001), we observed no significant change in the number of patients with identified aetiology (P = 0.35).ConclusionIn a nationwide cohort, the aetiology of AVB was identified in only half the patients younger than 50 years referred for first-time pacemaker implantation. The number of patients with unknown aetiology increased during the study period. These findings indicate need for better insight into aetiologies of AVB and improved diagnostic work-up guidelines.

IntroductionGenetic constitution and inflammation both contribute to development of coronary artery disease (CAD). Several CAD-associated single-nucleotide polymorphisms (SNPs) have recently been identified, but their functions are largely unknown. We investigated the associations between CAD-associated SNPs and five CAD-related inflammatory biomarkers.MethodsWe genotyped 45 CAD-associated SNPs in 701 stable CAD patients in whom levels of high-sensitivity C-reactive protein (hsRCP), interleukin-6, calprotectin, fibrinogen and complement component 3 levels had previously been measured. A genetic risk score was calculated to assess the combined risk associated with all the genetic variants. A multiple linear regression model was used to assess associations between the genetic risk score, single SNPs, and the five inflammatory biomarkers.ResultsThe minor allele (G) (CAD risk allele) of rs2075650 (TOMM40/APOE) was associated with lower levels of high-sensitivity C-reactive protein (effect per risk allele: -0.37 mg/l [95%CI -0.56 to -0.18 mg/l]). The inflammatory markers tested showed no association with the remaining 44 SNPs or with the genetic risk score.ConclusionsIn stable CAD patients, the risk allele of a common CAD-associated marker at the TOMM40/APOE locus was associated with lower hsCRP levels. No other genetic variants or the combined effect of all variants were associated with the five inflammatory biomarkers.