A moderate dose of caffeine ingestion does not change energy expenditure but decreases sleep time in physically active males: a double-blind randomized controlled trial

Research on the effect of caffeine on energy expenditure (EE), physical activity (PA), and total sleep time (TST) during free-living conditions using objective measures is scarce. We aimed to determine the impact of a moderate dose of caffeine on TST, resting EE (REE), physical activity EE (PAEE), total EE (TEE), and daily time spent in sedentary, light, moderate, and vigorous intensity activities in a 4-day period and the acute effects on heart rate (HR) and EE in physically active males. Using a double-blind crossover trial (ClinicalTrials.gov ID: NCT01477294) with two conditions (4 days each with 3-day washout) randomly ordered as caffeine (5 mg/kg of body mass/day) and placebo (maltodextrin) administered twice per day (2.5 mg/kg), 30 nonsmoker males, low-caffeine users (<100 mg/day), aged 20-39, were followed. Body composition was assessed by dual-energy X-ray absorptiometry. PA was assessed by accelerometry, while a combined HR and movement sensor estimated EE and HR on the second hour after the first administration dose. REE was assessed by indirect calorimetry, and PAEE was calculated as [TEE - (REE + 0.1TEE)]. TST and daily food records were obtained. Repeated measures ANOVA and ANCOVA were used. After a 4-day period, adjusting for fat-free mass, PAEE, and REE, TST was reduced (p = 0.022) under caffeine intake, while no differences were found between conditions for REE, PAEE, TEE, and PA patterns. Also, no acute effects on HR and EE were found between conditions. Though a large individual variability was observed, our findings revealed no acute or long-term effects of caffeine on EE and PA but decreased TST during free-living conditions in healthy males.

Use of chitosan scaffolds for repairing rat sciatic nerve defects

Neurotmesis must be surgically treated by direct end-to-end suture of the two nerve stumps or by a nerve graft harvested from elsewhere in the body in case of tissue loss. To avoid secondary damage due to harvesting of the nerve graft, a tube-guide can be used to bridge the nerve gap. Previously, our group developed and tested hybrid chitosan membranes for peripheral nerve tubulization and showed that freeze-dried chitosan type III membranes were particularly effective for improving peripheral nerve functional recovery after axonotmesis. Chitosan type III membranes have about 110 microm pores and about 90% of porosity, due to the employment of freeze-drying technique. The present study aimed to verify if chitosan type III membranes can be successfully used also for improving peripheral nerve functional recovery after neurotmesis of the rat sciatic nerve. Sasco Sprague-Dawley adult rats were divided into 6 groups: Group 1: end-to-end neurorrhaphy enwrapped by chitosan membrane type III (End-to-EndChitll); Group 2: 10mm-nerve gap bridged by an autologous nerve graft enwrapped by chitosan membrane type III (Graf180degreeChitIII); Group 3: 10 mm-nerve gap bridged by chitosan type III tube-guides (GapChitIII); These 3 experimental groups were compared with 3 control groups, respectively: Group 4: 10 mm-nerve gap bridged by an autologous nerve graft (Graft180degree); Group 5: 10 mm-nerve gap bridged by PLGA 90:10 tube-guides (PLGA); Group 6: end-to-end neurorrhaphy alone (End-to-End). Motor and sensory functional recovery were evaluated throughout a healing period of 20 weeks using extensor postural thrust (EPT), withdrawal reflex latency (WRL) and ankle kinematics. Regenerated nerves withdrawn at the end of the experiment were analysed histologically. Results showed that nerve regeneration was successful in all experimental and control groups and that chitosan type III tubulization induced a significantly better nerve regeneration and functional recovery in comparison to PLGA tubulization control. Further investigation is needed to explore the mechanisms at the basis of the positive effects of chitosan type III on axonal regeneration.

PLGA 90/10 and caprolactone biodegradable nerve guides for the reconstruction of the rat sciatic nerve

The purpose of this study was to test in vivo two different nerve guides for promoting nerve regeneration across a 10-mm gap of the rat sciatic nerve: 1) one made of PLGA in a novel proportion (90:10) of the two polymers poly(L-lactide):poly(glycolide); 2) another made of (DL-lactide-epsilon-caprolactone) copolyester (Neurolac) tube, by comparing its healing efficacy with that of the more traditional methods of end-to-end nerve suture and autologous graft. Motor and sensory functional recovery were assessed throughout the healing period of 20 weeks, and the repaired nerves were processed for morphological and histomorphometrical analysis. Both motor and sensory functions improved significantly in all experimental nerve repaired groups. At the end of the 20-week follow-up, the end-to-end group showed better recovery of motor function when compared with the groups treated with guiding tubes. However, at this time point, the level of motor function in the Neurolac(R) and PLGA groups was similar to the one of the graft group. Nociception function also recovered faster in the end-to-end group compared with the Neurolac(R) and PLGA groups, and in this case, recovery was also delayed in the graft group. At the end of follow-up, nociception was similar in all experimental groups. Morphological and histomorphometrical analysis showed that axon regeneration occurred in both PLGA and Neurolac(R) experimental groups, with no significant differences in the total number of regenerated fibers, but disclosed a different pattern of degradation of the two types of tubes with larger biodegradation of PLGA material by the end of 20 weeks. These results suggest that both types of biomaterials are a good substrate for preparing tubular nerve guides, and their different pattern of degradation does not seem to influence the degree of nerve regeneration.