The distribution of total vitamin b12 holotranscobalamin and the active vitamin b12 fraction in the first 5 weeks postpartum

Introduction Total vitamin B12 levels decrease significantly during pregnancy and recover to normal values within 8-week postpartum. Holotranscobalamin (holoTC) reflects the active part of vitamin B12 and has been shown to remain constant during pregnancy and postpartum. A mechanism of redistribution of vitamin B12 is suggested, with a shift toward holoTC if there is insufficient total vitamin B12 available. Our objective was to examine vitamin B12 deficiency and the active vitamin B12 fraction in postpartum women. Methods Total vitamin B12 and holoTC were measured in 171 women within 48 hours (T0) and at 5 weeks (T5) postpartum. Vitamin B12 deficiency was defined as total vitamin B12 < 180 pmol/L or holoTC <32 pmol/L. The active vitamin B12 fraction was defined as holoTC/total vitamin B12. Results Without intervention, vitamin B12 deficiency based on both serum total vitamin B12 and holoTC changed from 75% and 60%, to respectively 10% and 6% at T5. The fraction of active vitamin B12 was significant higher in vitamin B12 deficient women at both time points and across time (P < .0001 and P = .002). A high fraction of active vitamin B12 was only present in women with total vitamin B12 deficiency at T0. At T5, no high vitamin B12 fraction was found. Conclusion The changes in total vitamin B12 levels seem to be based on a physiological changes rather than vitamin B12 deficiency. The results of this study confirm the hypothesis that a shift toward the metabolic active vitamin B12 (holoTC) occurs in women with insufficient available total vitamin B12

Practice-based skill acquisition of pushrim-activated power-assisted wheelchair propulsion versus regular handrim propulsion in novices

BACKGROUND: Regular handrim wheelchair (RHW) propulsion is straining for the upper extremities and wheelchair users often experience overuse problems. A recent advancement in wheelchair technology that could assist users is the pushrim-activated power-assisted wheelchair (PAPAW). PAPAWs are challenging to control, yet it is unclear how people learn to use a PAPAW. The purpose of this study is to examine early skill acquisition through practice in PAPAWs and compare it with RHWs. METHODS: Twenty-four able-bodied novices were randomly allocated to either the RHW group or the PAPAW group. The experiment consisted of five sessions with three blocks of 4 min steady-state practice at 1.11 m/s and 0.21 W/kg. Finally, a transfer to the other mode was made. Data were collected with a drag-test, breath-by-breath spirometry, and a motion capture system. The last minute of each four-minute block was used for analysis. A mixed analysis of variance (ANOVA) was used to test for group, time, and interaction effects. RESULTS: Both groups improved their (assisted) mechanical efficiency, reduced their stroke rate, right-left and forward-backward deviation on the treadmill, and had a lower rate of perceived exertion (RPE) over time. (Assisted) mechanical efficiency was higher for the PAPAW group than for the RHW group and RPE was lower. However, left-right and forward-backward deviation was also found to be higher in the PAPAW group. CONCLUSIONS: At the group level the energetic cost of RHW and PAPAW propulsion can be lowered through low-intensity practice in novice users. The PAPAW is more 'efficient' than the RHW given the reduced energy requirement of the user from the motor assist, but more difficult to control. Future studies on PAPAWs should focus on the control needs of the user and their interaction with the power-assist technology

Trial discontinuation: lessons for future trial design?

Background: The current therapeutic arsenal still does not fulfill the therapeutic needs of inflammatory bowel disease patients. Although new drugs are constantly being developed, many will never reach the market. In this review we will search for reasons for discontinuing promising clinical trials and offer recommendation for future trials. Methods: The website clinicaltrials.gov was searched for interventional trials on novel inflammatory bowel disease therapies. Included were discontinued ‘Crohn’s disease’ and/or ‘colitis, ulcerative’ trials, started between July 1996 and October 2011 and discontinued. Pubmed was searched for publications to elucidate reasons for discontinuation. Results: One hundred and ninety one novel drug trials were published on clinicaltrials. gov, of which 24 (12.6%) were interrupted. The most common reason for discontinuation was lack of efficacy. Conclusion: Translation from bench to bedside is not always feasible, animal models come with restrictions. For better treatments, personalized medicine will be the future

Learning of Wheelchair Racing Propulsion Skills Over Three Weeks of Wheeling Practice on an Instrumented Ergometer in Able-Bodied Novices

The acquisition of daily handrim wheelchair propulsion skill as a multi-layered phenomenon has been studied in the past. Wheelchair racing, however, is considerably different from daily handrim wheelchair propulsion in terms of propulsion technique, as well as the underlying equipment and interface. Understanding wheelchair racing skill acquisition is important from a general motor learning and skill acquisition perspective, but also from a performance and injury prevention perspective. The aim of the current lab-based study was 2-fold: to investigate the evolution of racing wheelchair propulsion skill among a sample of novices and to compare them with an experienced wheelchair racer under similar conditions. A convenience sample of 15 able-bodied novices (8 male, 7 female) completed a standardized three-week submaximal uninstructed practice protocol (3 weeks, 3 sessions per week, 3x4 min per session) in a racing wheelchair on an ergometer. Required wheeling velocity was set at 2.78 m/s (10 km/h) and a rolling friction coefficient of 0.011 (resulting in a mean target load of 21W) was used. For comparison, an experienced T54 Paralympic athlete completed one block of the same protocol. Kinetics, kinematics, and physiological data were captured. A mixed effects regression analysis was used to examine the effect of practice for the novices, while controlling for speed. All participants finished the protocol successfully. However, not all participants were able to achieve the target speed during the first few sessions. Statistically significant improvements over time were found for all outcome measures (i.e., lower metabolic strain, longer push and cycle times) with the exception of mean power and torque per push. The athlete used a significantly greater contact angle and showed “better” outcomes on most metabolic and kinetic variables. While the athlete used a semi-circular propulsion technique, most participants used a double looping over technique. Three weeks of uninstructed wheelchair racing practice significantly improved efficiency and skill among a group of novices, in line with previous studies on daily handrim wheelchair propulsion. The comparison with an experienced athlete expectedly showed that there is still a large performance (and knowledge) gap to be conquered