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Abstract Background Myoelectric control of upper extremity powered prostheses has been used clinically for many years, however this approach has not been fully developed for lower extremity prosthetic devices. With the advent of powered lower extremity prosthetic components, the potential role of myoelectric control systems is of increasing importance. An understanding of muscle activation patterns and their relationship to functional ambulation is a vital step in the future development of myoelectric control. Unusual knee muscle co-contractions have been reported in both limbs of trans-tibial amputees. It is currently unknown what differences exist in co-contraction between trans-tibial amputees and controls. This study compares the activation and co-contraction patterns of the ankle and knee musculature of trans-tibial amputees (intact and residual limbs), and able-bodied control subjects during three speeds of gait. It was hypothesized that residual limbs would have greater ankle muscle co-contraction than intact and able-bodied control limbs and that knee muscle co-contraction would be different among all limbs. Lastly it was hypothesized that the extent of muscle co-contraction would increase with walking speed. Methods Nine unilateral traumatic trans-tibial amputees and five matched controls participated. Surface electromyography recorded activation from the Tibialis Anterior, Medial Gastrocnemius, Vastus Lateralis and Biceps Femoris of the residual, intact and control limbs. A series of filters were applied to the signal to obtain a linear envelope of the activation patterns. A co-contraction area (ratio of the integrated agonist and antagonist activity) was calculated during specific phases of gait. Results Co-contraction of the ankle muscles was greater in the residual limb than in the intact and control limbs during all phases of gait. Knee muscle co-contraction was greater in the residual limb than in the control limb during all phases of gait. Conclusion Co-contractions may represent a limb stiffening strategy to enhance stability during phases of initial foot-contact and single limb support. These strategies may be functionally necessary for amputee gait; however, the presence of co-contractions could confound future development of myoelectric controls and should thus be accounted for.

Objectives: To assess the visualization rate and size of the frontal horns (FHs) and cavum septi pellucidi (CSP) in healthy fetuses throughout pregnancy. Methods: After Institutional Review Board approval, 522 consecutive uncomplicated singleton pregnancies between 15 and 39 gestational weeks were enrolled in the study. Ultrasound measurements of the anterior horn width (AHW), center from the horn distance (CFHD), distance from the FHs to the CSP, and CSP width were retrospectively performed using axial transventricular or transcerebellar planes. Available maternal body mass indices were recorded. Results: At least 1 FH was seen in 78% of the cases. The mean AHW decreased over the second trimester and plateaued in the third trimester. The CFHD plateaued in the second trimester and increased in the third trimester. Downside FHs were generally larger than upside FHs. More FHs were measured in transventricular (69%) than transcerebellar (31%) planes. Frontal horns were seen with high, low, and no confidence in 57%, 21%, and 22% of cases, respectively. No‐confidence rates were 17% in the second trimester and 42% in the third trimester. The CSP was not visualized in 4% of cases; 15 of 19 cases of a nonvisualized CSP were scanned between 18 and 37 weeks. Mean body mass indices ± SDs were 27.6 ± 6.7 kg/m2 for the patients in cases of a visualized CSP and 32.4 ± 9.1 kg/m2 for the patients in cases of a nonvisualized CSP. Conclusions: Normative data for the fetal FH and CSP width were established. Frontal horns are more frequently seen on transventricular views and are difficult to confidently assess in the late third trimester. This study challenges previously reported data that the CSP is seen in 100% of cases from 18 to 37 weeks. [ABSTRACT FROM AUTHOR]

It was concluded that protein activity and fluorescence can be triggered simultaneously by coupling fluorescence to activity, an easily detectable florescent signal can be used as a convenient read-out of the phototriggering of protein activity.

To the Editor: The US Department of Labor recommends air-purifying respirators (e.g., N95, N99, or N100) as part of a comprehensive respiratory protection program for workers directly involved with avian [...]

Unilateral hand contractions increase activation in the motor cortex of the contralateral hemisphere, providing a means to alter the relative degree of activation in the right hemisphere versus the left hemisphere through spreading activation. Prior research reported enhanced verbal creativity as measured by performance on remote associate problems in Hebrew from left-hand contractions (right-hemisphere activation). We sought to extend the previous findings to English problems and to homograph interpretation. In Experiment 1, unilateral hand contractions in fact altered performance on the English remote associates, but in the direction of improved performance following right-hand contractions and left-hemisphere activation. In Experiment 2, the probability of retrieving atypical interpretations of homographs with multiple meanings was least likely for left-hemisphere dominant strong right handers, but the hand contraction manipulation had no effect. [ABSTRACT FROM AUTHOR]

The hip and ankle strategies that affect learning of a novel gait have not been fully determined, and could be of importance in design of clinical gait interventions. The authors' purpose was to determine the effects of asymmetric split-belt treadmill walking on ankle and hip work during propulsion. Participants were randomized into either a gradual training group or a sudden training group and later returned for a retention test. The gradual training group performed significantly more work at the hip joint of the slow limb during acquisition, and decreased the hip joint work performed during retention. These findings reveal the hip joint on the slow limb during initial swing as a possible site of adaptation to a novel locomotor pattern. [ABSTRACT FROM PUBLISHER]