Influence of Volatile Anesthesia on the Release of Glutamate and other Amino Acids in the Nucleus Accumbens in a Rat Model of Alcohol Withdrawal: A Pilot Study.

BACKGROUND: Alcohol withdrawal syndrome is a potentially life-threatening condition, which can occur when patients with alcohol use disorders undergo general anesthesia. Excitatory amino acids, such as glutamate, act as neurotransmitters and are known to play a key role in alcohol withdrawal syndrome. To understand this process better, we investigated the influence of isoflurane, sevoflurane, and desflurane anesthesia on the profile of excitatory and inhibitory amino acids in the nucleus accumbens (NAcc) of alcohol-withdrawn rats (AWR). METHODS: Eighty Wistar rats were randomized into two groups of 40, pair-fed with alcoholic or non-alcoholic nutrition. Nutrition was withdrawn and microdialysis was performed to measure the activity of amino acids in the NAcc. The onset time of the withdrawal syndrome was first determined in an experiment with 20 rats. Sixty rats then received isoflurane, sevoflurane, or desflurane anesthesia for three hours during the withdrawal period, followed by one hour of elimination. Amino acid concentrations were measured using chromatography and results were compared to baseline levels measured prior to induction of anesthesia. RESULTS: Glutamate release increased in the alcohol group at five hours after the last alcohol intake (p = 0.002). After 140 min, desflurane anesthesia led to a lower release of glutamate (p < 0.001) and aspartate (p = 0.0007) in AWR compared to controls. GABA release under and after desflurane anesthesia was also significantly lower in AWR than controls (p = 0.023). Over the course of isoflurane anesthesia, arginine release decreased in AWR compared to controls (p < 0.001), and aspartate release increased after induction relative to controls (p20min = 0.015 and p40min = 0.006). However, amino acid levels did not differ between the groups as a result of sevoflurane anesthesia. CONCLUSIONS: Each of three volatile anesthetics we studied showed different effects on excitatory and inhibitory amino acid concentrations. Under desflurane anesthesia, both glutamate and aspartate showed a tendency to be lower in AWR than controls over the whole timecourse. The inhibitory amino acid arginine increased in AWR compared to controls, whereas GABA levels decreased. However, there were no significant differences in amino acid concentrations under or after sevoflurane anesthesia. Under isoflurane, aspartate release increased in AWR following induction, and from 40 min to 140 min arginine release in controls was elevated. The precise mechanisms through which each of the volatile anesthetics affected amino acid concentrations are still unclear and further experimental research is required to draw reliable conclusions.

Undergraduate technical skills training guided by student tutors--analysis of tutors' attitudes, tutees' acceptance and learning progress in an innovative teaching model.

BACKGROUND: Skills labs provide a sheltered learning environment. As close supervision and individual feedback were proven to be important in ensuring effective skills training, we implemented a cross-year peer tutor system in our skills lab of internal medicine that allowed intense training sessions with small learning groups (3-4 students) taught by one student tutor. METHODS: The expectations, experiences and criticisms of peer tutors regarding the tutor system for undergraduate skills lab training were investigated in the context of a focus group. In addition, tutees' acceptance of this learning model and of their student tutors was evaluated by means of a pre/post web-based survey. RESULTS: 14 voluntary senior students were intensely prepared by consultants for their peer tutor activity. 127 students participated in the project, 66.9% of which responded to the web-based survey (23 topics with help of 6-point Likert scale + free comments). Acceptance was very high (5.69 +/- 0.07, mean +/- SEM), and self-confidence ratings increased significantly after the intervention for each of the trained skills (average 1.96 +/- 0.08, all p < 0.002). Tutors received high global ratings (5.50 +/- 0.07) and very positive anonymous individual feedback from participants. 82% of tutees considered the peer teaching model to be sufficient, and a mere 1% expressed the wish for skills training to be provided by faculty staff only. Focus group analyses with tutors revealed 18 different topics, including profit in personal knowledge and personal satisfaction through teaching activities. The ratio of 1:4 tutor/tutees was regarded to be very beneficial for effective feedback, and the personalized online evaluation by tutees to be a strong motivator and helpful for further improvements. The tutors ascribed great importance to the continuous availability of a contact doctor in case of uncertainties. CONCLUSION: This study demonstrates that peer teaching in undergraduate technical clinical skills training is feasible and widely accepted among tutees, provided that the tutors receive sufficient training and supervision.