Absence of M-Ras modulates social behavior in mice.

BACKGROUND: The molecular mechanisms that determine social behavior are poorly understood. Pheromones play a critical role in social recognition in most animals, including mice, but how these are converted into behavioral responses is largely unknown. Here, we report that the absence of the small GTPase M-Ras affects social behavior in mice. RESULTS: In their interactions with other males, Mras(-/-) males exhibited high levels of territorial aggression and social investigations, and increased fear-related behavior. They also showed increased mating behavior with females. Curiously, increased aggression and mating behaviors were only observed when Mras(-/-) males were paired with Mras(-/-) partners, but were significantly reduced when paired with wild-type (WT) mice. Since mice use pheromonal cues to identify other individuals, we explored the possibility that pheromone detection may be altered in Mras(-/-) mice. Unlike WT mice, Mras(-/-) did not show a preference for exploring unfamiliar urinary pheromones or unfamiliar isogenic mice. Although this could indicate that vomeronasal function and/or olfactory learning may be compromised in Mras(-/-) mice, these observations were not fully consistent with the differential behavioral responses to WT and Mras(-/-) interaction partners by Mras(-/-) males. In addition, induction of c-fos upon pheromone exposure or in response to mating was similar in WT and Mras (-/-) mice, as was the ex vivo expansion of neural progenitors with EGF. This indicated that acute pheromone detection and processing was likely intact. However, urinary metabolite profiles differed between Mras(-/-) and WT males. CONCLUSIONS: The changes in behaviors displayed by Mras(-/-) mice are likely due to a complex combination of factors that may include an inherent predisposition to increased aggression and sexual behavior, and the production of distinct pheromones that could override the preference for unfamiliar social odors. Olfactory and/or social learning processes may thus be compromised in Mras(-/-) mice.

Pre-Clerkship Observerships to Increase Early Exposure to Geriatric Medicine.

BACKGROUND AND PURPOSE: To foster interest in geriatric care, the Queen's Geriatrics Interest Group (QGIG) collaborated with the Division of Geriatric Medicine to arrange a Geriatrics Pre-Clerkship Observership Program. METHODS: Forty-two pre-clerkship medical students participated in the program between October 2013 and May 2014. Participants were paired with a resident and/or attending physician for a four-hour weekend observership on an inpatient geriatric rehabilitation unit. The program was assessed using: (1) internally developed Likert scales assessing student's experiences and interest in geriatric medicine before and after the observership; (2) University of California Los Angeles-Geriatric Attitudes Scale (UCLA-GAS); and (3) narrative feedback. RESULTS: All participants found the process of setting up the observership easy. Some 72.7% described the observership experience as leading to positive changes in their attitude toward geriatric medicine and 54.5% felt that it stimulated their interest in the specialty. No statistically significant change in UCLA-GAS scores was detected (mean score pre- versus post-observership: 3.5 ± 0.5 versus 3.7 ± 0.4; p=.35). All participants agreed that the program should continue, and 90% stated that they would participate again. CONCLUSIONS: The observership program was positively received by students. Structured pre-clerkship observerships may be a feasible method for increasing exposure to geriatric medicine.