The effect of surgical repair of the chest on postural stability among patients with pectus excavatum.

Pectus excavatum is the most encountered of chest wall deformities. It may produce respiratory and cardiovascular symptoms, hence surgical repair of this defect is performed. The procedure involving the insertion of metal bars under the sternum (the Nuss procedure) usually brings significant improvement to patients. However, the effect of the repair on the postural stability of patients has not been studied so far. To investigate the problem of patients' stability in the postoperative period male patients with pectus excavatum (n = 21) and healthy controls (n = 22) were included in the study. Using posturography methods, we showed a negative impact of the pectus excavatum repair surgery on patients' postural stability in the first postoperative phase. The centre of pressure displacement parameters used to measure postural stability were lower after the repair for both, the frontal and sagittal plane as well as for the velocity of displacements in the sagittal plane in the double stance with eyes open. Poorer postural stability was also found in patients with pectus excavatum when compared to healthy controls. Our findings may be useful for functional monitoring in the evaluation and surgical management of pectus excavatum patients and also when designing the rehabilitation of patients undergoing the Nuss procedure.

Establishment of a social conditioned place preference paradigm for the study of social reward in female mice.

Social interactions can be and often are rewarding. The effect of social contact strongly depends on circumstances, and the reward may be driven by varied motivational processes, ranging from parental or affiliative behaviors to investigation or aggression. Reward associated with nonreproductive interactions in rodents is measured using the social conditioned place preference (sCPP) paradigm, where a change in preference for an initially neutral context confirms reinforcing effects of social contact. Here, we revised the sCPP method and reexamined social reward in adult female mice. Contrary to earlier studies, we found that robust rewarding effects of social contact could be detected in adult (14-week-old) female C57BL/6 mice when the sCPP task was refined to remove confounding factors. Strikingly, the rewarding effects of social interaction were only observed among female siblings who remained together from birth. Contact with same-age nonsiblings was not rewarding even after 8 weeks of cohousing. Other factors critical for the social reward effect in the sCPP paradigm included the number of conditioning sessions and the inherent preference for contextual cues. Thus, we show that social interaction is rewarding in adult female mice, but this effect strictly depends on the familiarity of the interaction partners. Furthermore, by identifying confounding factors, we provide a behavioral model to study the mechanisms underlying the rewarding effects of nonreproductive social interaction in adult mice.