Characterization and validation of a split belt treadmill for measuring hindlimb ground-reaction forces in able-bodied and spinalized felines.

BACKGROUND: The measurement of ground reaction forces (GRFs) in animals trained to locomote on a treadmill after spinal cord injury (SCI) could prove valuable for evaluating training outcomes; however, quantitative measures of the GRFs in spinal felines are limited. NEW METHOD: A split belt treadmill was designed and constructed to measure the GRFs of feline hindlimbs during stepping. The treadmill consists of two independent treadmill assemblies, each mounted on a force plate. The design allows measurements of the vertical (F RESULTS: Static and dynamic noise tests revealed little to no noise at frequencies below 6Hz. Validation of the force plate measurements with a hand-held force sensor force showed good agreement between the two force readings. Peak normalized (to body mass) vertical GRFs for intact cats were 4.89±0.85N/kg for the left hindlimb and 4.79±0.97N/kg for the right. In comparison, trained spinalized cats peak normalized vertical GRFs were 2.20±0.94N/kg for the left hindlimb and 2.85±0.99N/kg for the right. COMPARISON WITH OTHER EXISTING METHODS: Previous methods of measuring GRFs used stationary single force plates or treadmill mounted to single force plate. Using independent treadmills for each hindlimb allows measurement of the individual hindlimb\u27s GRFs in spinalized cats following body-weight supported treadmill training. CONCLUSIONS: The split belt force treadmill enables the simultaneous recording of ground-reaction forces for both hindlimbs in cats prior to spinalization, and following spinalization and body-weight-supported treadmill training (BWST)

Comparison of prevalence of depression in mothers of twins and mothers of singletons

OBJECTIVE\ud \ud To determine whether the apparent additional and exceptional stresses associated with bearing and parenting twins affect the emotional wellbeing of mothers. SETTING--Great Britain, 1970-5. \ud \ud DESIGN\ud \ud Cohort study of 13,135 children born between 4 April and 11 April 1970. Mothers of all children, both singletons and twins, were interviewed by health visitors (providing demographic data) and completed a self report measure of emotional well-being (the Rutter malaise inventory) when the child was 5 years of age. The malaise scores of mothers of twins were compared with those of all mothers of singletons and then with those of mothers categorised by the age spacing of their children (only one child, widely spaced, or closely spaced), taking account of maternal age, social class, and whether the study child had a disability, by using logistic regression. \ud \ud SUBJECTS\ud \ud 139 mothers of twins--122 pairs of twins and 17 twins whose cotwin had died--and 12,573 controls, who were mothers of singletons. \ud \ud RESULTS\ud \ud A significantly higher proportion of mothers of twins at 5 years had malaise scores indicative of depression than mothers of singletons at the same age. Mothers who had borne twins, one of whom had subsequently died, had the highest malaise scores and were three times more likely than mothers of singletons to experience depression. Both mothers of twin pairs and mothers of singletons closely spaced in age were at significantly higher risk of experiencing depression than mothers of children widely spaced in age or mothers of only one child (p less than 0.0001). Odds ratios indicated that the risk of depression in mothers of twins was higher than that in mothers of closely spaced singletons. \ud \ud CONCLUSION\ud \ud Mothers of twins are more likely to experience depression. This suggests a relation between the additional and exceptional stresses that twins present and the mother's emotional wellbeing