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At least 577 records · Page 32Linked to original sources
PubMed1992

Effects of trimethyltin on repeated acquisition (learning) in the radial-arm maze.

Trimethyltin (TMT) was used as a positive control neurotoxicant to evaluate a repeated acquisition procedure for the 8-arm radial maze. Ten male Long-Evans rats were trained to collect a single food pellet at the end of each baited arm on each trial of a daily 12-trial test session. Four of the eight arms were baited on all trials of a given session. The set of four baited arms was changed each day: thus the rats were required to learn a new set of baited arms in each session. In trained rats, error frequencies (entries into unbaited arms) declined from about 4 on Trial 1 to less than 1 on Trials 4-12 in each session: this within-session error reduction thus defined an acquisition baseline which was evaluated for its sensitivity to TMT. Learning was impaired after 7 mg/kg (iv) TMT, as shown by a slower decline in within-session error frequencies in all treated rats. Errors and response times were elevated for 5 weeks after TMT but returned to control levels thereafter. Histological examination of hippocampi showed damage in all treated rats 18 weeks after treatment; however, no significant relationship between degree of damage and behavioral effect was observed. Analysis of errors showed that TMT more strongly impaired the rats' ability to avoid arms in the current unbaited set than those baited arms already entered on a given trial (i.e., working memory). These dissociations between behavior and hippocampal morphology in terms of time course, magnitude of effect across animals, and error type suggest that performance of this task does not depend upon hippocampal integrity, as do other tasks involving spatial working memory. Recovery of function in this kind of task may shed light on processes of neural plasticity after exposure to neurotoxic compounds.

Animals↗
PubMedDate not supplied

Is arm span an accurate measure of height to predict pulmonary function parameters?

UNLABELLED: Interpretation of pulmonary function tests basically depends on prediction of normal values derived from equations using non-deformed body height. In many patients body height can not be accurately measured. The arm-span method has been used for estimating body height, but the normal relationship between body height and arm span is not exact and differs in various ethnic groups and even between two genders of the same race. In order to minimise the error of estimation of non-deformed body height, the normal relationship between body height and arm span was determined for 754 Persian males and 708 females aged 7 to 82 years, all having normal body stature. In accordance with earlier reports, two sets of spirometric parameters derived once from height, sex, age; and again from arm-span, sex, age were statistically different, and overestimated when the measured arm-span was used. The body-height/arm-span relationship is described using linear regression equations; in subgroups aging 20 years or less and those older than 20 in different genders. The results indicate significant sex and age differences in the arm-span/height ratio. Two sets of spirometric parameters predicted by real height, sex, age/and predicted height, sex, age were not statistically different for most of the parameters especially vital capacity. IN CONCLUSION: height estimated from arm span, performs much better than arm span to predict pulmonary function parameters.

Adolescent↗
PubMed1998

Inferior dislocation of the glenohumeral joint combined with the compartment syndrome of the upper arm: case report.

Compartment syndromes occurring in the forearm and leg are not infrequent. However, reports of compartment syndrome of the upper arm are conspicuously rare. Inferior dislocation of the shoulder combined with compartment syndrome has rarely been reported in the literature. We report our experience with a patient with inferior dislocation of the glenohumeral joint combined with compartment syndrome of the upper arm. A 29-year-old man had traumatic inferior dislocation of the glenohumeral joint combined with severe swelling of the shoulder and upper arm. After close reduction, the shoulder and upper arm were still tensely swollen. Compartment pressure of the upper arm was measured using a digital manometer (Quick Pressure Monitor 295-1, Stryker) and remained very high, thus, fasciotomy was performed. After debridement and skin graft, the arm healed without sequelae. When a patient has a fracture dislocation of the shoulder joint associated with a swollen arm, compartment syndrome of the upper arm should be included as a differential diagnosis. Detecting the compartment pressure can confirm the diagnosis of compartment syndrome objectively.

Adult↗
PubMed2003

Factors influencing arm and axillary symptoms after treatment for node negative breast carcinoma.

BACKGROUND: The purpose of the current study was to identify the factors that contribute to postoperative arm symptoms following breast conserving surgery in a well-defined cohort of node negative breast carcinoma patients. METHODS: A convenience sample of 370 women >/= 50 years of age with node negative breast carcinoma who were participants in a randomized controlled trial designed to assess the need for breast radiation in addition to tamoxifen were surveyed. Axillary dissection was optional for patients 65 years or older and who were clinically node negative. RESULTS: A total of 65.1% (241/370) of women had ipsilateral shoulder or arm symptoms. Multivariate analysis revealed that axillary dissection, breast radiation, and younger age (odds ratio = 11.2, 1.65, and 3.8 respectively) were significantly (P < 0.05) associated with increased ipsilateral shoulder or arm symptoms. Treatment with axillary dissection and breast radiation were significant factors (P < 0.02) associated with the self-reporting of arm swelling (odds ratio = 4.4 and 2.0, respectively). Patients 70 years old or greater reported significantly fewer arm symptoms (odds ratio = 0.26, P < 0.05) after axillary dissection. CONCLUSIONS: Arm symptoms were present in about 80% of patients who underwent breast conserving surgery, axillary dissection, and breast radiation in the current study. These symptoms were significantly associated with the use of axillary dissection, breast radiation, and younger age. Older patients experienced fewer arm symptoms after standard treatment for node negative breast carcinoma, and thus older age should not be a contraindication to axillary dissection.

Age Factors↗
PubMed1994

Misdirections in slow, goal-directed arm movements are not primarily visually based.

In a previous study we found that the initial direction of slow, goal-directed arm movements deviates consistently from the direction of the actual straight line between the starting position and the target position. We now investigate whether these deviations are caused by imperfections or peculiarities in the processing of vision-related spatial information, such as retinal information, and eye- and head-position information. This could lead to incorrect localization of the target relative to the starting position. Subjects were seated in front of a horizontal surface and had to move their arm slowly and accurately in the direction of target positions. We varied the amount of vision-related spatial information. In experiment 1, subjects were presented with visual targets and could see their moving arm. In experiment 2, the subjects were again presented with visual targets, but now they could not see their moving arm. In experiment 3, the subjects were blindfolded and had to move their arm towards tactile targets. In all three experiments we found comparable consistent deviations in the initial movement direction. We also instructed congenitally and early-blind subjects to move their arm towards tactile targets. Their performance showed deviations congruous with those found in the sighted subjects, and possibly somewhat larger. We conclude that the deviations in the initial movement direction of slow, goal-directed arm movements are not primarily visually based. The deviations are generated after all spatial information has been integrated.

Adult↗
PubMed1991

Activity patterns of upper arm muscles in relation to direction of rapid wrist movement in man.

Adjustment of arm posture associated with rapid wrist movements was studied by EMG analysis. Seven healthy adults, seated and holding their right arm with the shoulder in a neutral position with the elbow in 90 degrees flexion and the wrist position neutral, were instructed to flex or extend the wrist as fast as possible. To examine whether the activity patterns of the upper arm muscles were related to the prime mover or the direction of the movement in space, the forearm was in two postures, supinate and pronate. The surface EMGs of biceps brachii, brachialis, triceps brachii and the prime movers were recorded along with the angular displacement of the wrist. The sequences of the upper arm muscle activities changed in relation to the direction of the movement. The earliest activities of the upper arm muscles were considered to counteract the dynamic perturbation induced by the rapid wrist movement. The onsets of the earliest activity of the upper arm muscles preceded the movement onset by 50-60 ms. These results revealed that the activity patterns of the arm muscles associated with the rapid wrist movements were functionally compatible with the anticipatory postural adjustment and were controlled according to the direction of the movement in space.

Adult↗
PubMed1981

Visually triggered eye-arm movements in man.

The degree of temporal coupling and the nature of temporal ordering between the gaze (eye-head) and arm motor systems was studied in normal subjects by measuring the reaction time, RT, of each system to randomly generated visual signals presented along the horizontal meridian: (1) at two spatial locations, 15.5 degrees and 29.1 degrees, (2) to the right and left of a central fixation point, and (3) with and without room illumination. Upon detecting the visual signal, the subject was instructed to guide the arm from its rest position upon a supporting table and to extinguish the light source by touching a metal disc enclosing the stimulus "as quickly and accurately as possible." The results indicated (1) saccadic eye motion initiated gaze towards the target, (2) a change in the eccentric position of the target was associated with alteration of the eye and arm RT by a similar value; the interval between eye and the subsequent arm RT was invariant with spatial location no matter the presence or absence of room illumination, and (3) the arm RT increased when visual information of the environment was not available. It is postulated that a visual stimulus triggers a command system releasing a patterned sequence of eye-hand-arm motion; the initiation of motion in these motor systems is based upon the same retinal error calculation; however, no rigid rule can be established for the serial ordering or temporal sequencing of motion between the triggered motor systems. The temporal arrangement between head and arm with eye can be modified, at least in part, by alterations in supraspinal control of postural mechanisms and/or motoneuronal excitability of the responding muscles prior to motion.

Adolescent↗
PubMed1995

Visual stability with goal-directed eye and arm movements toward a target displaced during saccadic suppression.

This experiment tested whether the perceived stability of the environment is altered when there is a combination of eye and visually open-loop hand movements toward a target displaced during the eye movements, i.e., during saccadic suppression. Visual-target eccentricity randomly decreased or increased during eye movements and subjects reported whether they perceived a target displacement or not, and if so, the direction of the displacement. Three experimental conditions, involving different combinations of eye and arm movements, were tested: (a) eye movements only; (b) simultaneous eye and rapid arm movements toward the target; and (c) simultaneous eye and arm movements with a restraint blocking the arm as soon as the hand left the starting position. The perceptual threshold of target displacements resulting in an increased target eccentricity was greater when subjects combined eye and arm movements toward the target object, specially for the no-restraint condition. Subjects corrected most of their arm trajectory toward the displaced target despite the short movement times (average MT = 189 ms). After the movements, the null error feedback of the hand's final position presumably overlapped the retino-oculomotor signal error and could be responsible for the deficient perception of target displacements. Thus, subjects interpreted the terminal hand positions as being within the range of the endpoint variability associated with the production of rapid arm movements rather than as a change of the environment. These results suggest that a natural strategy adopted for processing spatial information, especially in a competing situation, could favour a constancy tendency avoiding systematic perception of a change of environment for any noise or variability at the central or peripheral levels.

Adult↗
PubMed2004

How dependent are grip force and arm actions during holding an object?

In everyday life, when manipulating objects, arm actions and precision grip force are tightly coupled by the central nervous system. To investigate the extent of this neural coupling, 11 subjects were asked to perform tasks that encourage either the coupling (Task 1) or the dissociation (Task 2 and 3) of grip force and arm actions. During Task 1, subjects held a grasping device, with an extra load suspended underneath by a string. Then, using the other hand, subjects were asked to lift or release the suspended load, while maintaining unaffected the posture of the grasping arm. During Task 2, while holding the device, subjects received similar instructions, but this time the extra load was suspended underneath the forearm. During Task 3, subjects were explicitly asked to modulate their grip force without moving the arm. In Task 1, grip force changed in parallel with, or slightly ahead of, changes in load, which is consistent with the view of a feedforward mechanism making grip force largely subordinate to ongoing arm actions. In Task 2, even though subjects had no obvious reasons to modulate their force (i.e. the load of the device was constant) they did so, with a number of features that resemble performance in Task 1. In Task 3, as expected, voluntary modulations in grip force had no effect on arm actions. It is concluded that the neural coupling between arm actions and grip force (1) can possibly lead to clumsy reactions, (2) depends on the focal action, and (3) is only unidirectional.

Adult↗
PubMed2006

Predictive control of grip force when moving object with an elastic load applied on the arm.

Skilled object manipulation relies on the capability to adjust the grip force according to the consequences of our movements in terms of the resulting load force of the object. Such predictive grip force control requires (at least) two neural processes: (1) predicting the kinematic characteristics of the unfolding arm trajectory and (2) predicting the load force on the object resulting, among other factors, from the arm movement. The goal of this study was to examine whether subjects can still anticipate the resulting load force on the object when the moving arm is submitted to a type of load that does not contribute to the object load. To this end, 12 subjects were asked to rhythmically move a 0.4 kg object under three different conditions. In the first condition (ARM), an elastic cord was attached to the upper arm. In the second condition, the elastic cord was attached to the object (OBJECT). In the third condition, the elastic cord was absent (NO ELAST). At the kinematic level, results showed no influence of the elastic cord on the pattern of movement of the object. At the kinetic level, cross-correlation analyses between grip force and load force acting on the object revealed significant correlations with minimal delays. In addition, grip force profiles were similar under the ARM and NO ELAST conditions, both differing from the OBJECT condition. Overall, we interpret these results as evidence that the neural processes involved in the prediction of the arm trajectory and those involved in the prediction of the load on the object held can take into account different external force fields, thereby preserving the functionality of the behaviour.

Adult↗
PubMed2006

Muscle activation and cutaneous reflex modulation during rhythmic and discrete arm tasks in orthopaedic shoulder instability.

In orthopaedic shoulder instability, muscle activity (EMG) is altered during unconstrained discrete arm movement tasks (e.g. elevation against a load). These findings have been ascribed to deficits in afferent feedback and neural control with glenohumeral instabilities resulting from orthopaedic injury. However, the integrity of neural control during shoulder movements in those with unstable shoulders is unclear. It is not known if there are altered EMG patterns during rhythmic arm movement or during discrete tasks involving no load, as would be experienced in many arm motions performed in daily living. The primary objective of this study was to evaluate neural control of arm movements between those with unstable shoulders and control participants, within a constrained arm movement paradigm involving both rhythmic arm cycling and discrete reaching. To achieve this objective, we determined if the amplitude and timing of EMG related to the movement pattern (background EMG) was significantly different between groups. Cutaneous reflexes were used to simulate a perturbation to the upper limb that would typically evoke a coordinated response. In the elevation phase of the movement path for anterior and posterior deltoid, upper trapezius, infraspinatus and serratus anterior, background EMG during rhythmic arm cycling was significantly (24%, p < 0.05) larger in unstable shoulders than in controls. No differences were found in background EMG between the groups during the discrete task. Significant differences (p < 0.05) were also noted in cutaneous reflexes between groups for both the rhythmic and discrete tasks with the reflex amplitudes being either increased or reduced in unstable shoulders as compared to controls. The differences in the background EMG and the cutaneous reflexes patterns in those with shoulder instabilities suggest that neural control is altered during rhythmic movement.

Adult↗
PubMed2001

Development of postural adaptation to arm raising.

We studied the development of the coordination between posture and movement by analyzing the shifts of the center of pressure (CoP) associated with arm raising. Three groups of children aged 3-5 years, 6-8 years, and 9-10 years and an adult group were tested. The subjects were required to raise their arms to the horizontal position while standing still, with their hands free or loaded (5% of the body weight). The arm movements were recorded by a TV-image processor, and the changes in position of the CoP were measured by a force platform and analyzed before, during, and after the arm movement. The data show that the CoP moved forward during arm raising, that additional load induced a greater shift in all age groups, and that the relative amplitude of the shift decreased with age. The greatest changes occurred between ages 3-5 years and 6-8 years. The pre- and postmovement CoP shift suggests qualitative changes in the postural adaptation to movement between these two age groups: the anticipatory postural adjustments moved from a supporting function to a compensatory function, yielding an increasing functional convergence between the feedforward and the feedback modes of postural control, and an increasing rapidness in recovering postural stability after arm movement. The postural behavior shown by the 9- to 10-year-old children and by the adults in the arms-free condition suggests an increased tolerance to unbalance when postural oscillations do not jeopardize static equilibrium.

Adaptation, Physiological↗
PubMed2001

Postural coordination patterns associated with the swinging frequency of arms.

Voluntary arm movements frequently perturb body equilibrium in an upright posture. The motions of leg joints need to be coordinated according to the properties of voluntary arm movements in order to maintain body equilibrium, and this may cause a change in postural pattern. The purpose of this study was to determine whether the kinematic pattern generation of upright posture is influenced by a change in the swinging frequency of arm movements and whether the pattern generation is correlated with a change in joint torque about the shoulder joint. Four male subjects in an upright posture were instructed to swing their arms at seven different frequencies, determined by the maximum swinging frequency of each subject (35%max, 40-60%max, 65%max). Segment rotations around the shoulder, hip, and ankle joints were analyzed at kinematic and kinetic levels. The results of kinematic analysis indicated that tight coupling between motions of the shoulder and hip joints was generated in lower-frequency trials (under 40-45%max), whereas tight coupling between motions of the shoulder and ankle joints was generated in higher frequency trials (more than 40-45%max). Furthermore, the results of kinetic analysis revealed that changes in the joint torque patterns about the shoulder and hip joints occurred in trials at 40-45%max. The mean value of 40-45%max was close to the eigenfrequency of each subject's arm. We concluded that (1) postural patterns associated with a gradual change in the swinging frequency of the arms can be divided into two coordination modes (a hip-shoulder in-phase mode and an ankle-shoulder in-phase mode), and (2) these two patterns may be divided by the eigenfrequency of the arm.

Adult↗
PubMedDate not supplied

Placement of the VenaTech LP caval filter in the elderly: feasibility and clinical benefits of insertion via the arm.

PURPOSE: To evaluate routine use of access sites in the arm for percutaneous caval filter placement (PCFP) in elderly patients. Neck arthritis, patient anxiety, access site thrombosis or fecal/urinary incontinence complicating jugular or femoral access may require alternative access sites in this population. METHODS: Access via the right arm was chosen for PCFP (VenaTech LP). The indication for PCFP was deep vein thrombosis, a history of pulmonary embolism, and a contraindication to anticoagulant therapy. Ultrasound-guided puncture was performed after diameter measurement of the arm veins (ØAV). The filter was inserted with standard imaging procedures. Procedural difficulty was graded and compared with ØAV and the angle from the arm vein to the superior vena cava (alphaAV/SVC). RESULTS: Over 2 years, 16 patients (14 women, 2 men) with an average age of 90 years (range 79-97 years) were included in the study. The average ØAV value of the basilic or brachial veins was 4.2 mm (range 3.0-5.1 mm). The minimal ØAV for successful access was determined after the first 15 patients. No hematoma occurred at the puncture sites. The average alphaAV/SVC value was 62 degrees (range 29 degrees -90 degrees ). Arm access was possible in 12 of 16 patients (75%) with ØAV >or= 3.5 mm and alphaAV/SVC >or= 29 degrees . Every procedure via the arm was graded "easy" by the operator, regardless of angulation values. Femoral access was used in one case due to the impossibility of traversing the heart (patient no. 2), and jugular access was used in 3 of 16 (19%) patients due to puncture failure (patient no. 4), small ØAV (3 mm) (patient no. 6), and stenosis of the distal right subclavian vein (patient no.16), respectively. CONCLUSION: PCFP via the arm can be routinely accomplished in patients older than 75 years, provided ØAV >or= 3.5 mm, and alphaAV/SVC >or= 29 degrees .

Aged↗
PubMed2000

Estimation of %VO2 reserve from heart rate during arm exercise and running.

The purpose of the present investigation was to examine the relationship between the percent heart rate reserve (%HRR) in arm exercise and the corresponding percent oxygen uptake (VO2) reserve, and to compare this relationship to that occurring in running. Fourteen male physical education students took part in the study. Each subject performed a maximal running exercise test and a maximal arm cycling test. The subjects also performed three submaximal exercise bouts (in both exercise modes) at 30%, 60% and 80% of their HRR. The subjects were monitored for their heart rate (HR) at rest, maximal HR (HRmax), HR at submaximal work loads. maximal VO2 (VO2max), VO2 at rest and VO2 at submaximal loads. For each subject, load and exercise mode, %HRR and %VO2 reserve were calculated (from HRmax and VO2max as measured during running and arm cycling) and the relationship between the two was evaluated. The main finding of the present investigation is that the prediction of %VO2 reserve in arm cycling from %HRR is grossly overestimated when calculated from HRmax and VO2max measured during running. The prediction is better but still overestimated when calculated from HRmax and VO2max measured during arm cycling. The findings indicate a better prediction of %VO2 reserve from %HRR for running than for arm exercise. These findings should be taken into consideration when prescribing the target HR for arm training.

Adult↗
PubMed1991

Arm and leg blood pressures--are they really so different in newborns?

Controversy still exists over differences between upper and lower limb blood pressures (BP) in neonates. We measured upper arm and calf systolic (S) and diastolic (D) BP and heart rate (HR) using 2 Dinamap 847 instruments simultaneously every half minute for several measurement periods of 5-10 min. Nine healthy term newborns were studied in active (AS) and quite (QS) sleep on post-natal days 1 and 5. The results were examined using unbalanced analyses of variance. Arm SBP was 62.3 +/- 1.6 mmHg and DBP 35.5 +/- 1.0 mmHg on day 1 in AS and QS. Calf values were not significantly different but were slightly higher (by 2-3 mmHg) in AS. Arm SBP and DBP rose by 8.5 and 5 mmHg, respectively, between days 1 and 5 but calf pressures rose less. Calf SBP and DBP were significantly lower (by 4.6 and 3.4 mmHg, respectively) than the arm values in QS on day 5. Arm SBP and DBP were dependent on post-natal age but not on sleep state while calf SBP and DBP and HR were dependent on both. Mean HR rose with age from 114 to 117.6 bpm in QS and from 118.6 to 122.4 bpm in AS. Our non-invasive BP measurements were similar to available invasive data. We postulate that differences in arm and calf vasoreactivity account for the different dependence on sleep state and for the unequal changes in arm and calf BE from days 1 to 5.

Age Factors↗
PubMed1994

Colour Doppler demonstrates venous flow abnormalities in breast cancer patients with chronic arm swelling.

Chronic arm oedema following breast cancer treatment is traditionally attributed to lymphatic obstruction, with venous obstruction as an infrequent complicating factor. The axillo-subclavian venous systems of 81 patients with arm swelling following breast cancer treatment were examined with colour Doppler, duplex Doppler and grey scale ultrasound. Over half (57%) had evidence of venous outflow obstruction and a further 14% had signs of venous "congestion". Only 30% of the swollen arms had normal venous outflow. The venous systems of the contralateral non-swollen arms were all normal as were both arms in 28 control patients who had similar treatment but had not developed arm swelling. These findings suggest that venous outflow obstruction is an important contributory factor in the pathophysiology of arm swelling following breast cancer treatment.

Adult↗
PubMed2006

Validity of accelerometry for monitoring real-world arm activity in patients with subacute stroke: evidence from the extremity constraint-induced therapy evaluation trial.

OBJECTIVE: To examine the psychometric properties of an objective method for assessing real-world arm activity in a large sample with subacute stroke. DESIGN: Validation study. SETTING: Community. PARTICIPANTS: Persons 3 to 9 months poststroke (N=169) with mild to moderate motor impairment of their hemiparetic arm enrolled in a multisite, randomized clinical trial of constraint-induced movement therapy. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Participants wore an accelerometer on each arm outside the laboratory for 3 days before and after treatment or an equivalent no-treatment period. They also completed the Actual Amount of Use Test (AAUT), which is an observational measure of spontaneous more-impaired arm use, and the Motor Activity Log (MAL), which is an interview assessing more-impaired arm use in daily life. RESULTS: Low-pass-filtered accelerometer recordings were reliable (r range, >.8) and stable (P range, >.48). Their validity was also supported. Correlations calculated across all participants at baseline between the ratio of more-impaired to less-impaired arm accelerometer recordings and AAUT and MAL scores were .60 and .52, respectively. CONCLUSIONS: Accelerometry provides an objective, real-world index of more-impaired arm activity with good psychometric properties.

Activities of Daily Living↗