How does cervical spinal cord injury impact the cardiopulmonary response to exercise?

We compared cardiopulmonary responses to arm-ergometry in individuals with cervical spinal cord injury (C-SCI) and able-bodied controls. We hypothesized that individuals with C-SCI would have higher respiratory frequency (fb) but lower tidal volume (VT) at a given work rate and dynamically hyperinflate during exercise, whereas able-bodied individuals would not. Participants completed pulmonary function testing, an arm-ergometry test to exhaustion, and a sub-maximal exercise test consisting of four-minute stages at 20, 40, 60, and 80% peak work rate. Able-bodied individuals completed a further sub-maximal test with absolute work rate matched to C-SCI. During work rate matched sub-maximal exercise, C-SCI had smaller VT (main effect p < 0.001) compensated by an increased fb (main effect p = 0.009). C-SCI had increased end-expiratory lung volume at 80% peak work rate vs. rest (p < 0.003), whereas able-bodied did not. In conclusion, during arm-ergometry, individuals with C-SCI exhibit altered ventilatory patterns characterized by reduced VT, higher fb, and dynamic hyperinflation that may contribute to the observed reduced aerobic exercise capacity.

Cardiovascular control, autonomic function, and elite endurance performance in spinal cord injury.

We aimed to determine the relationship between level of injury, completeness of injury, resting as well as exercise hemodynamics, and endurance performance in athletes with spinal cord injury (SCI). Twenty-three elite male paracycling athletes (C3-T8) were assessed for neurological level/completeness of injury, autonomic completeness of injury, resting cardiovascular function, and time to complete a 17.3-km World Championship time-trial test. A subset were also fitted with heart rate (HR) monitors and their cycles were fitted with a global positioning systems device (n = 15). Thoracic SCI exhibited higher seated systolic blood pressure along with superior time-trial performance compared with cervical SCI (all P < 0.01). When further stratified by autonomic completeness of injury, the four athletes with cervical autonomic incomplete SCI exhibited a faster time-trial time and a higher average speed compared with cervical autonomic complete SCI (all P < 0.042). Maximum and average HR also tended to be higher in cervical autonomic incomplete vs autonomic complete. There were no differences in time-trial time, HR, or speed between thoracic autonomic complete vs incomplete SCI. In conclusion, autonomic completeness of injury and the consequent ability of the cardiovascular system to respond to exercise appear to be a critical determinant of endurance performance in elite athletes with cervical SCI.

Assessment of the lateral diffusion and penetration of topically applied drugs in humans using a novel concentric tape stripping design.

PURPOSE: To determine the extent of lateral spread and stratum corneum (SC) penetration of caffeine (CAF), hydrocortisone (HC) and ibuprofen (IBU) using a novel concentric tape stripping technique. METHOD: Ethanolic solutions of CAF, HC or IBU were applied to the forearm of 8 volunteers. At various time points, 10 successive layers of SC were removed by stripping with tapes perforated into concentric rings and analysed for drug concentration and mass of SC protein. In vitro permeation studies assessed the percutaneous absorption of these compounds across human skin. RESULTS: CAF and IBU showed significant lateral spreading across the SC while HC formed a drug depot at the site of application. Relative to the applied dose, the in vivo recovery of all compounds from the combined 10 strips at 3 mins ranged between 83.0 and 92.9 % and decreased to between 64.5 and 66.9 % at 3 h. IBU recovery further decreased to 47.7 ± 5.6 % at 6 h, correlating with greater in vitro penetration relative to CAF and HC. CONCLUSION: Drug concentration decreased with increased lateral distance from the application site. The lower recovery of IBU in the upper tape strip regions compared to CAF and HC may be a consequence of greater penetration into the SC with time.

Morphometric and steroid hormone changes associated with experimental anovulatory follicles in the sow.

Steroid levels and ovarian follicular morphology were examined in sows on days 19 and 26 (day 5 of next cycle) after injection of adrenocorticotropic hormone (ACTH) or dexamethasone (DXM). Five sows received DXM (30 micrograms/kg bodyweight, intramuscularly) at 12 h intervals from days 9 to 14. Another five sows were given ACTH (2 IU/kg bodyweight, intramuscularly) from day 17 to day 19 or the end of estrus. Five control sows received no treatment. Ovulation occurred only in control sows and progesterone was significantly elevated at day 26. Estradiol values in ovarian vein blood were low but variable on day 19 in DXM- and ACTH-treated animals. Androstenedione values were lower (p less than 0.05) on both days in sows receiving DXM but not in those given ACTH compared to control values on day 19. Morphometric analysis, based on six follicles in each of three sows from each treatment group, indicated that follicular and antral diameters and granulosa cell numbers did not differ for either hormone treatment group on either day compared to those of control sows on day 19. The mitotic index suggested that cell replication continued. However, pyknotic and karyorrhectic nuclei were also seen in the hormone treatment groups. Follicles and oocytes from both DXM- and ACTH-treated sows showed signs of early degenerative changes including disorganization of cumulus cells and large lipid droplets in the cytoplasm of oocytes. Significant differences from control follicles in granulosa cell density and theca interna cell density suggested an association with the altered steroid hormone secretion.