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In order to better understand the role of the vestibular system in postural adjustments on unstable surfaces, we analyzed the effects of galvanic vestibular stimulation (GVS) on the pattern of muscle activity and joint displacements (ankle knee and hip) of eight intellectually normal participants (control group--CG) and eight control group individuals with Down syndrome (DS) while balancing on seesaws of different heights. The CG individuals adopted a pattern of muscle activation characterized by alternation between ankle agonist and antagonist muscles. The individuals with DS adopted a pattern of muscle co-contraction. The GVS affected neither the ability of CG individuals to maintain balance nor their pattern of muscle contraction. On the other hand, the individuals with DS showed greater sensitivity to GVS while balancing on a seesaw and were not able to select the appropriate motor strategy to efficiently balance and compensate the effects of GVS. These increased vestibular sensitivities observed in individuals with DS can reflect deficits in the proprioceptive system. (Contains 3 figures and 2 tables.)

Background: The purpose of this study was to investigate the kinematic and electromyography strategy used by individuals with intellectual disability to keep equilibrium during anterior-posterior balance on seesaws with different degrees of instability. Method: Six individuals with Down syndrome (DS) and six control group individuals (CG) balanced on three seesaws. The movement of the hip, knee and ankle joints and electromyography activities of selected leg and trunk muscles were recorded. Results: Both groups maintained their balance mainly at the ankle joint. Contrary to the CG, the individuals with DS adopted a pattern of co-contraction and were not able to modulate the magnitude of postural response with the seesaw's degree of instability. Conclusions: These unusual strategies used by individuals with DS, such as their inability to discriminate different levels of mechanical demands in terms of the seesaw's instability, can reflect deficits in the proprioceptive system. The integration at cerebellum level could be a good candidate.

Climatic conditions that are thermally inappropriate for dairy cattle are associated with a reduction in feed consumption, production, and the composition of the final product. The objective of this research was to identify the influence of the evaporative adiabatic cooling system (EACS) on the thermal comfort and productive responses of dairy cattle, through multivariate analysis by principal components, in the summer and winter seasons of the semiarid region of Pernambuco, Brazil. The data came from an experiment that included 16 multiparous lactating cows, randomly distributed in 4 sets, with 4 experimental phases and 4 treatments (0, 10, 20, and 30 min of exposure to EACS). Multivariate analysis was used utilizing principal components for the thermal comfort indexes, physiological variables, milk production, and composition. The highest milk production in the summer season was for animals exposed to the cooling system for 30 min. In the winter season in the morning shift, the use of the evaporative cooling system for 10 min was sufficient for improvements in milk production. The times of exposure to EACS caused changes in the composition of milk, both in summer and in winter. Thermal stress was characterized by a high temperature and humidity index in all treatments in the afternoon shift. The principal component analysis allowed us to identify the positive influence of evaporative cooling on thermal comfort, physiological responses, production, and composition milk of lactating cows. [ABSTRACT FROM AUTHOR]

A number of studies have analyzed various indices of the final position variability in order to provide insight into different levels of neuromotor processing during reaching movements. Yet the possible effects of movement kinematics on variability have often been neglected. The present study was designed to test the effects of movement direction and curvature on the pattern of movement variable errors. Subjects performed series of reaching movements over the same distance and into the same target. However, due either to changes in starting position or to applied obstacles, the movements were performed in different directions or along the trajectories of different curvatures. The pattern of movement variable errors was assessed by means of the principal component analysis applied on the 2-D scatter of movement final positions. The orientation of these ellipses demonstrated changes associated with changes in both movement direction and curvature. However, neither movement direction nor movement curvature affected movement variable errors assessed by area of the ellipses. Therefore it was concluded that the end-point variability depends partly, but not exclusively, on movement kinematics. [ABSTRACT FROM AUTHOR]

Objective: To describe a new surgical technique of the first case of totally laparoscopic repair of primary obstructive congenital megaureter with pyeloplasty, intracorporeal excisional tailoring of the ureter and nonrefluxing ureteroneocystostomy., Methods: A 15-year-old male presented with obstructive megaureter. The standard three-port transperitoneal pyeloplasty technique and an additional 5-mm port for dynamic traction were used. Pelvic and ureteral dissection, pyeloplasty, intracorporeal excisional ureteral tailoring and nonrefluxing ureteroneocystostomy were all completed laparoscopically. A double-J stent was used to calibrate the ureter., Results: Operative time was 240 min. No intra and postoperative complications were observed, and there was discharge on postoperative day 2. The patient was pain-free and without urinary tract infection during the 4-month period after surgery. Follow up revealed complete resolution of the ureteral obstruction and adequate pelvic and ureteral caliber., Conclusion: Laparoscopic pyeloplasty, intracorporeal excisional tailoring, and non-refluxing reimplantation are safe and effective for the treatment of obstructive congenital megaureter. The totally laparoscopic approach is reproducible and provides low morbidity with inherent cosmetic advantages., (Copyright © 2012 AEU. Published by Elsevier Espana. All rights reserved.)

Introduction: laparoendoscopic single-site surgery (LESS) using transumbilical access and conventional laparoscopic instruments is a very attractive alternative to perform ureterolithotomy for ureteral stone with failed endourological management., Material and Method: a 29-year-old woman presented with chronic right lumbar pain and a 1.2 cm impacted calculus localized at transition of abdominal to pelvic ureter. Semi-rigid ureteroscopy had failed to fragment the stone and shockwave lithotripsy was not available. Double-J ureteral catheter had been inserted preoperatively. We performed a transumbilical single-incision laparoscopic ureterolithotomy. Three conventional trocars were inserted in a single semi-circular umbilical incision. Right colon was detached and the ureter was identified. Calculus was extracted and the ureteral incision was closed with intracorporal sutures., Results: ureterolithotomy was successfully completed, with all the operative steps performed transumbically. Operative time was 180 minutes. No single-port device or articulating and bent instruments were utilized. Estimated blood loss was less than 50 mL. No intraoperative, access-related and postoperative complications took place. The duration of hospitalization was 24 hours and scarless appearance was observed on postoperative day 15., Conclusion: transumbilical single-incision laparoscopic ureterolithotomy is feasible and safe. This approach offers an inherent cosmetic advantage and few postoperative discomfort. Additional experience and continued investigation are warranted., (Copyright © 2010 AEU. Published by Elsevier Espana. All rights reserved.)

Purpose: This study tested the hypothesis that muscle and interaction torques can be altered independently in order to improve in specific kinematics performance observed following practice. We also tested the hypothesis that a simple set of rules of EMG-control and kinetic-control models could explain the EMG and kinetic changes due to practice of movements with reversal., Scope: Kinematics of the upper arm with reversal, performed over three distances, was reconstructed using motion analysis. The muscle and interaction torques were calculated using inverse-dynamics. EMG activities of the major arm muscles were also recorded. The results demonstrate that improved performance is facilitated by an increase in muscle torque (and therefore acceleration) at the proximal joint (shoulder) and by an increase in the interaction torque at the distal joint (elbow). No changes were observed in the amount of muscle activity underlying these kinetic modifications, except for a decrease in the shoulder antagonist latency., Conclusion: The results confirm Bernstein's idea that the central nervous system takes advantage of the passive-interactive properties of the moving system. Also the modulation of the EMG patterns should be explained taking in account the reactive forces and the dual functions (maintenance of posture and generation of movement) of the muscles.

In this study we investigated the hypothesis that the simple set of rules used to explain the modulation of muscle activities during single-joint movements could also be applied for reversal movements of the shoulder and elbow joints. The muscle torques of both joints were characterized by a triphasic impulse. The first impulse of each joint accelerated the limb to the target and was generated by an initial burst of the muscles activated first (primary mover). The second impulse decelerated the limb to the target, reversed movement direction and accelerated the limb back to the initial position, and was generated by an initial burst of the muscles activated second (secondary movers). A third impulse, in each joint, decelerated the limb to the initial position due to the generation of a second burst of the primary movers. The first burst of the primary mover decreased abruptly, and the latency between the activation of the primary and secondary movers varied in proportion with target distances for the elbow, but not for the shoulder muscles. All impulses and bursts increased with target distances and were well coupled. Therefore, as predicted, the bursts of muscle activities were modulated to generate the appropriate level of muscle torque.

This work investigates the kinematic and electromyography (EMG) strategy used by the central nervous system (CNS) to keep equilibrium during anterior-posterior balance on seesaws with different degrees of instability. The movement of hip, knee, and ankle were reconstructed using a 3D motion-analysis system and the EMG activities of selected ankle, knee, and hip muscles were recorded. Balance was kept mainly at the ankle joint. The EMG patterns of the gastrocnemius and anterior tibialis alternated between agonist and antagonist bursts. The agonist burst started before the end of the lengthening phase and was prolonged until the end of the shortening phase. The EMG activities of the muscles crossing the knee and hip joints were characterized by a pattern of generalized co-activation. The movements at these two joints were very small, suggesting a neural or biomechanical constraint underlying the operations of the equilibrium control. Our results also indicate that the strategy to keep balance on the seesaw is qualitatively the same for the different levels of mechanical demands in terms of the seesaw's instability.

In previous studies of rapid elbow movements in young healthy men, characteristic task-dependent changes in the patterns of muscle activation when movement speed or distance was varied have been reported. In the present study, the authors investigated whether age or gender is associated with changes in the patterns of muscle activity previously reported in young men. Arm movements of 10 healthy older and 10 healthy younger participants (5 men and 5 women in each group) were studied. Surface electromyograms (EMGs) from agonist (biceps) and antagonist (triceps) muscles, kinematic and kinetic parameters, as well as anthropometric and strength measures were recorded. All 4 groups of participants showed similar task- (distance or speed) dependent changes in biphasic EMG activity. Similar modulation of the initial rate of rise of the EMG, integrated agonist and antagonist EMG activity, as well as their relative timing were observed in all 4 groups. Those results suggest that older individuals of both genders retain the control strategies for elbow movements used by young individuals. Despite the qualitative similarities in the patterns of muscle activation, the men moved more quickly than the women, and younger participants moved more quickly than older participants. Those performance differences could not be explained in terms of differences in body size and strength alone.

We examined the systematic variation in shoulder and elbow torque, as well as movement kinematics, for horizontal-plane arm movements with direction reversals performed by normal individuals and individuals with Down syndrome. Eight neurologically normal individuals and eight individuals with Down syndrome performed horizontal, planar reversal movements to four different target locations. The four locations of the targets were chosen such that there is a systematic increase in elbow interaction torque for each of the four different target locations. This systematic increase in interaction torque has previously been shown to lead to progressively larger movement reversal errors, and trajectories that do not show a sharp reversal of direction, for movements to and from the target in patients who have proprioceptive abnormalities. We computed joint torques at the elbow and shoulder and found a high correlation between elbow and shoulder torque for the neurologically normal subjects. The ratio of joint torques varied systematically with target location. These findings extend previously reported findings of a linear synergy between shoulder and elbow joints for a variety of point-to-point movements. There was also a correlation between elbow and shoulder torque in individuals with Down syndrome, but the magnitude of the correlation was less. The ratio of joint torques changed systematically with target direction in individuals with Down syndrome but was slightly different from the ratio observed for neurologically normal individuals. The difference in the ratio was caused by the generation of proportionately more elbow torque than shoulder torque. The fingertip path of individuals with Down syndrome showed a sharp reversal in moving toward and then away from the target. In this respect, they were similar to neurologically normal individuals but dissimilar to individuals with proprioceptive deficits. Finally, we observed that individuals with Down syndrome spend proportionately more time in the vicinity of the target than normal individuals. Collectively these results show that there is a systematic relationship between joint torques at the elbow and shoulder. This relationship is present for reversal movements and is also present in individuals with Down syndrome.

We examined the patterns of joint kinematics and torques in two kinds of sagittal plane reaching movements. One consisted of movements from a fixed initial position with the arm partially outstretched, to different targets, equidistant from the initial position and located according to the hours of a clock. The other series added movements from different initial positions and directions and >40-80 cm distances. Dynamic muscle torque was calculated by inverse dynamic equations with the gravitational components removed. In making movements in almost every direction, the dynamic components of the muscle torques at both the elbow and shoulder were related almost linearly to each other. Both were similarly shaped, biphasic, almost synchronous and symmetrical pulses. These findings are consistent with our previously reported observations, which we termed a linear synergy. The relative scaling of the two joint torques changes continuously and regularly with movement direction. This was confirmed by calculating a vector defined by the dynamic components of the shoulder and elbow torques. The vector rotates smoothly about an ellipse in intrinsic, joint torque space as the direction of hand motion rotates about a circle in extrinsic Cartesian space. This confirms a second implication of linear synergy that the scaling constant between the linearly related joint torques is directionally dependent. Multiple linear regression showed that the torque at each joint scales as a simple linear function of the angular displacement at both joints, in spite of the complex nonlinear dynamics of multijoint movement. The coefficients of this function are independent of the initial arm position and movement distance and are the same for all subjects. This is an unanticipated finding. We discuss these observations in terms of the hypothesis that voluntary, multiple degrees of freedom, rapid reaching movements may use rule-based, feed-forward control of dynamic joint torque. Rule-based control of joint torque with separate dynamic and static controllers is an alternative to models such as those based on the equilibrium point hypotheses that rely on a positionally based controller to produce both dynamic and static torque components. It is also an alternative to feed-forward models that directly solve the problems of inverse dynamics. Our experimental findings are not necessarily incompatible with any of the alternative models, but they describe new, additional findings for which we need to account. The rules are chosen by the nervous system according to features of the kinematic task to couple muscle contraction at the shoulder and elbow in a linear synergy. Speed and load control preserves the relative magnitudes of the dynamic torques while directional control is accomplished by modulating them in a differential manner. This control system operates in parallel with a positional control system that solves the problems of postural stability.

This case report describes an 11-year-old boy with spastic diplegia whose reflex status, range of motion (ROM), strength, and motor performance were measured before and after implantation of an indwelling system for delivery of intrathecally administered baclofen. Before baclofen use, the subject experienced clonus that interfered with walking, needed assistance with transfers, and was unable to independently put on underwear and socks. Measures of spasticity, kinematics and electromyographic activity during voluntary movements, ROM, Gross Motor Function Measure (GMFM) scores, and self-reports of change were obtained at baseline, before and after bolus baclofen injection, during a double-blind placebo-controlled clinical trial of baclofen administration via an indwelling pump, and after 1 and 2 years of baclofen therapy. Spasticity, Babinski reflexes, clonus, strength, and coactivation of antagonist muscles during voluntary movement were decreased shortly after baclofen administration began. Hip and ankle ROM increased, upper-extremity movement speed increased, independence in dressing and transfers improved, and orthoses were discarded. After 1 and 2 years, GMFM scores were 7.8% and 6.4% above baseline, respectively; the subject won a fitness award. After 2 years, ROM was worse than at baseline and concerns regarding hip subluxation arose. Single-joint movement control and independence improved and spasticity decreased during baclofen administration.

We studied the effects of extensive practice of fast, unidirectional, single-joint elbow flexions against a small extending torque bias upon the kinematic and electromyographic (EMG) characteristics of the movements as well as upon the reconstructed hypothetical control patterns (equilibrium trajectories). The subjects were tested at different distances, both with and without the bias torque prior to and after the practice sessions. The basic finding was paradoxical: The subjects did not improve their performance at the practiced task (against the bias) and at other distances in the same condition; however, they showed an increase in movement speed and a decrease in movement time at all distances in unpracticed conditions (without the bias). Changes in the EMG patterns were similar in both conditions. We hypothesize that the principle of learning the dynamics of interaction with the experimental setup in combination with a very steep learning curve form the basis for the observed paradoxical effects of practice. The equilibrium-point hypothesis of movement control provides the least controversial description of these effects as compared to the force-control and EMG-control approaches.

The purpose of this article is to review the literature on the effects of intrathecally administered baclofen on impairment in spasticity and muscle activation patterns, on functional limitations in mobility and self-care, and on disability in daily life roles. We found plentiful evidence of improvement in spasticity, spasms, and bladder function and some reports of improved patterns of muscle activation and kinematics of single-joint movement. Improved ability to accomplish transfers, self-care, and locomotion is less consistently studied but has also been reported in about 60% to 70% of patients. Evidence of improved quality of life is primarily anecdotal but may be found in 10% to 30% of patients. We conclude that research protocols should be developed to clarify effects on control of voluntary movement, functional limitations, and quality of life.

Background and Purpose: The purpose of this study was to investigate the effects of prolonged practice of a simple motor task (a fast, unidirectional single-joint movement) on different indexes of motor performance in individuals with Down syndrome., Subjects: Eight individuals with Down syndrome were tested before and after practice involving 1,100 movements., Methods: The test consisted of three series of elbow flexion movements. In the first series, the subjects were asked to move "as fast as possible" over four distances. In the second series, the subjects moved over one distance at a "comfortable speed." The initial position of the elbow joint for these two series of movements was 55 degrees into flexion (full elbow extension equals 0 degrees). In the third series, the subjects were also asked to move "as fast as possible" over two distances, but from another initial elbow position (73 degrees into flexion)., Results: After training over a 2-week period, all subjects improved their performance on all tasks as reflected by both kinematic and electromyographic data. In particular, they increased the quantity of the agonist activity, decreased the antagonist onset latency, and doubled their peak velocity. They were able to transfer the improvement in their performance to the nontrained distances and to the different starting position. Subjects decreased their movement time by proportionally decreasing both the acceleration and deceleration times., Conclusion and Discussion: This study supports the idea that subjects with Down syndrome can use patterns of muscle activation that are qualitatively indistinguishable from those used by individuals who are neurologically normal. With appropriate training, individuals with Down syndrome achieved similar levels of motor performance to that described in the literature for individuals who are neurologically normal.

Preprogrammed reactions to unexpected loadings and unloadings of an elbow joint resisting an extending bias load were studied in subjects with Down syndrome. The subjects were instructed to either "let go" or "return back as fast as possible." Both predictable and unpredictable perturbation directions were used. Integrated electromyograms of the two elbow flexors and two elbow extensors were used to characterize the preprogrammed reactions. All the subjects were able to modulate their preprogrammed reactions in response to a change in the instruction. They were also able to grade the preprogrammed responses corresponding to the magnitude of the perturbation. Two basic patterns of modulation were observed, "reciprocal" and "coactivation." There were no effects of the predictability of the perturbation direction. Reconstructed joint compliant characteristics suggested an unchanged gain in the arc of the tonic stretch reflex. We propose that there are no abnormalities in the preprogrammed reactions of some individuals with Down syndrome. The apparent "clumsiness" of individuals with Down syndrome in a changing environment is assumed to reflect an adaptation to their impaired decision-making ability. The high variability of motor performance in subjects with Down syndrome may result from mixing different strategies for solving motor tasks.

Analysis of variability of fast aimed movements predicts the properties of trajectory variance. The analysis is based on a kinematic model with nonlinear changes in "internal time". The purpose of the work was to identify different sources of variability and their influence on the trajectory variance. An analytical expression for the speed-accuracy trade-off is introduced. Experiments were performed with subjects making single-joint elbow flexion movements over different distances as fast as possible with their eyes closed to memorized targets. Standard deviation of movement trajectory increased during the first part of the movement and subsequently decreased. The variance peaked after the time of peak velocity, close to the time of peak deceleration. A dependence of the trajectory variance on movement distance (speed-accuracy trade-off) was seen during the movement (at times of peak velocity and peak deceleration) but not after the movement termination. We conclude that the previously reported drop in the variability of movement trajectory during the deceleration phase does not necessarily mean a compensation by the control system but may result from purely kinematic properties of the movement. The importance of the time of measurement for analysis of the speed-accuracy trade-offs is emphasized.

The time delay between the onset of muscle activation and the onset of force or motion is commonly referred to as electromechanical delay, motor time, or motor execution time. This time has been used in the study of reaction time, of physiological properties of muscle, and of population differences. In this study, we show that electromechanical delay is comprised of two components. The first is transport time (t(t)) which is very brief (perhaps 10 ms). The second is the time to generate detectable changes in force (t(f)). The absolute duration of electromechanical delay is usually dominated by the second component which is influenced by four separate factors that are related in the following way: [Formula: see text] That is, t(f) is a function (g) of the product of two ratios. One is between the threshold T of the measuring device and the rate R at which muscle force rises. The other is the ratio of the mechanical impedances of the measuring device (Z(d)) and the muscle (Z(m)). We conclude that the measured absolute value of electromechanical delay has no physiological or psychological meaning and that task and performance induced changes need great care in their interpretation., (Copyright © 1992. Published by Elsevier Ltd.)