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Hand preference and hand skill was assessed in two broad age groups of children with autism, children with learning disabilities, and control schoolchildren. The first group comprised children ages 3-5 years and the second group of children ages 11-13 years. Degree of handedness remained relatively stable across age groups, particularly within the autistic and learning-disabled populations. The main difference was between the subject groups, with the normal controls more lateralized than either the children with autism or children with learning disabilities. As with degree of handedness, consistency of handedness also differed significantly between subject groups with the normal controls more consistent in their hand preference than the other two groups. In addition, younger children were less consistent in their hand preference than older children. However, the present study found no evidence of a dissociation of hand skill and hand preference in children with autism compared to children with learning disabilities and normal developing children.
Neuroimaging studies suggest that the primary hand motor area and the cerebellum play a pivotal role in the control of finger tapping, but their differential contribution in this task is unknown. We used therefore repetitive transcranial magnetic stimulation (rTMS) in its virtual lesion mode (1 Hz, 10 min, 90% of motor threshold) to study the effects of transient disruption of the right lateral cerebellum (CB), the left primary hand motor area (M1), and the right brachial plexus (PL, control site) on various finger tapping tasks (paced finger tapping task: PFT; tapping with maximum speed: TAPMAX, and tapping with convenient speed: TAPCON) in healthy right-handed subjects. RTMS of the left M1 slowed finger tapping speed of the right hand in the TAPMAX task. This effect eliminated the right hand superiority in the TAPMAX task. In addition, rTMS of the left M1 resulted in slower tapping speeds for both hands during TAPCON. There were no other effects of rTMS on tapping speed or tapping variability. Findings indicate that M1 is essential for generating fastest finger movements.
We studied 135 hands in 77 Japanese patients to assess the frequency of radial involvement and its association with recurrence and the Dupuytren's diathesis. The radial aspect of the hand was affected in 22% of the hands. Diseased cords were observed in ten patients who underwent surgery on the radial aspect of the hand. Longitudinal cords on the radial side of thenar eminence and distal transverse interdigital cords were common. The radial aspect of the hand was the most common site of disease extension, though recurrence never occurred after excision of a radial lesion. Ectopic lesions, bilateral hand involvement, and recurrence were significantly more frequent in patients with the radial side involvement. Thus the results of this study suggest that radial side disease is associated with the Dupuytren's diathesis and is a risk factor of recurrence.
The hypothesis that fluent braille readers use both hands simultaneously to read was tested. Video tape recordings of finger movements by ten students reading prose text were subjected to frame by frame analyses of synchronous finger positions. The hypothesis was not borne out. Touching a letter by one hand was paired most often with simultaneous touching of a space between letters or between words by the other hand. Simultaneous touching of letters by the two hands was least frequent and did not differ from simultaneous touching of gaps between letters. Further evidence against the hypothesis came from analyses of the time relations between the two hands at the beginning and end of lines. It was argued that fluency does not depend on simultaneous processing of the same type of information, but on fast intermittent alternation in function between the two hands.
A method is described for comparing the shapes of tetrameric proteins whose three-dimensional structure is known. The centres of mass of single subunits are calculated as Cartesian co-ordinates with respect to their three dyad axes. The axes are allocated on the basis of the extent of the intersubunit contacts that they relate. This results in the division of proteins into two classes called right-handed and left-handed. A second division, which also contains right-handed and left-handed forms, is made according to the distances between the centres of mass of the subunits measured across the two axes with the most extensive contacts. Two other parameters have been calculated from the coordinates; they are named "aplanarity" and "twist". The eight tetramers so far investigated are discussed. One, lactate dehydrogenase, cannot be treated in this way. Among the others, right-handed structures (according to both definitions) are found to be commoner; most have low twist; all are of fairly high aplanarity except phosphoglycerate mutase. Prealbumin is exceptional, being left-handed in both ways and of high twist; it has a figure-of-eight structure with the centres of mass lying in one plane. The changes in the quaternary structure of haemoglobin are also presented by using this approach; on deoxygenation the aplanarity and the twist decrease.
To analyze the load on the lumbar spine and the motion pattern of a body during a backhand stroke when playing tennis, kinematic and kinetic data of eleven amateur tennis players were collected. Each subject performed one-handed and double-handed strokes at low, medium, and high racket speeds. The three-dimensional motion of the strokes was optically measured by tracking markers attached to their body segments. Floor reaction forces were measured for the right and left feet separately. Using the body motion and the floor reaction force data, the lower lumbar spine moment was calculated based on a segment-link model. Peak and plateau values of the joint moment before and after ball impact were analyzed statistically using a factorial ANOVA (stroke, racket speed). Similarly, the axial rotation angle of the pelvis against the feet and that of the shoulder against the pelvis were analyzed. In all the moments except the lateral bending moment before ball impact and all the rotation angles, there were significant main effects of racket speed. The one-handed strokes showed significantly smaller extension moment before ball impact as well as smaller lateral bending and axial rotation moments after ball impact than the double-handed strokes. The one-handed strokes also showed a significantly smaller axial rotation angle of the shoulder against the pelvis and that of the pelvis against the feet. These results indicate that during one-handed strokes the shoulder and elbow joints share the rotational motion necessary for backhand strokes and consequently reduce the maximal moments imposed on the spinal joints.
In the present investigation, we addressed the relation between manual preference and performance. A total of 52 right-handers and 48 left-handers were tested for manual proficiency and preferences using a range of tasks. Self-professed right-and left-handers showed greater preference for, and superior performance with, the preferred hand. Left-handers use their nonpreferred hand more often and in some instances are more skilled with it than right-handers. There was a subgroup of persons with mixed handedness, who identified themselves as left-handed, wrote with the left hand, and were more skilled with the left hand on dot-filling, but who were otherwise right-handed. Overall, the data indicated that a complete description of handedness will only be provided by careful consideration of the nature of the preference and performance measures one uses.
BACKGROUND AND PURPOSE: Hand-assisted laparoscopic (HAL) renal surgery is an accepted standard of practice. We report our complications at the hand port-site incision in various HAL urologic procedures. PATIENTS AND METHODS: Data and follow-up were complete for 54 patients who underwent HAL nephrectomy. HAL partial nephrectomy, or HAL nephroureterectomy at our institution from October 2001 to April 2003. A retrospective review of the patients' charts was performed to identify the incidence of postoperative hand port-site complications. The mean patient age was 59 years, and the mean follow-up was 5.4 months. RESULTS: Five complications were observed in four patients (9.3%). One patient had a superficial wound infection (1.9%) and an incisional hernia (1.9%) that was surgically repaired. One patient had a superficial incisional breakdown that healed well after conservative measures. One obese patient with severe chronic obstructive pulmonary disease eviscerated through his hand-port incision after a coughing spell. This was repaired operatively, and the patient healed well with the aid of an abdominal binder. One patient developed an enterocutaneous fistula at her hand-port site that healed well after both operative and conservative management. CONCLUSIONS: The technique of HAL renal surgery is safe and effective. Complications associated with the hand-port incision exist, and as they become better defined, the surgeon may take extra steps toward their recognition and prevention.
There is debate in the handedness literature over proficiency and preference measures are indicators of common underlying factors, or separate dimensions of behavior with different causes. It has been argued that hand preference has different origins from hand proficiency on the grounds that (i) the two types of measure are imperfectly correlated and (ii) distributions of relative hand proficiency are normal or nearly so, whereas distributions of hand preference are J-shaped. A model is described in which the probability that one hand will be preferred for a given activity is directly proportional to the relative proficiency of the two sides, the latter being normally distributed. It is shown that imperfect correlations between proficiency and preference measures, and J-shaped distributions of preference, can be predicted by such a model. These facts about hand preference and proficiency do not, therefore, go against the view that preference is determined by proficiency.
Kinesin is a double-headed motor protein that moves along microtubules in 8-nanometer steps. Two broad classes of model have been invoked to explain kinesin movement: hand-over-hand and inchworm. In hand-over-hand models, the heads exchange leading and trailing roles with every step, whereas no such exchange is postulated for inchworm models, where one head always leads. By measuring the stepwise motion of individual enzymes, we find that some kinesin molecules exhibit a marked alternation in the dwell times between sequential steps, causing these motors to "limp" along the microtubule. Limping implies that kinesin molecules strictly alternate between two different conformations as they step, indicative of an asymmetric, hand-over-hand mechanism.
15 male undergraduates were presented with 10-sided random forms which they explored visually, or one-handed haptically, or two-handed haptically. Forms were exposed for various durations and subjects were required to draw each form immediately after its removal. The results indicated that 30 sec. of one-handed exploration and 20 and 30 sec. of two-handed exploration produced performance comparable to just 2 sec. of visual exploration. Two-handed exploration was significantly superior to one-handed exploration only at the 20-sec. exposure duration. These results illustrate the disparity in the information-gathering capabilities between the visual and haptic systems.
Asymmetry of hand performance was investigated with the paper-and-pencil test of hand dominance originally developed by Steingruber in 1971. This test, originally constructed to measure asymmetry of hand performance in children, gave appropriate scores on asymmetry of hand performance in adults if a shorter time limit than originally proposed was applied. Asymmetry of hand performance in adults as measured with the new instruction showed reliable asymmetries in performance which are similar to those obtained on different widely accepted tests measuring asymmetries of hand performance.
The purpose of this study is to compose between hand scaling with abd without the calculus solvent gel (sofscale) and ultrasonic instrumentation at clinical and SEM level. 30 patients belonging to the age group of 17-50 year were selected. Patients selected were subjected to three different scaling modalities namely hand scaling (control), hand scaling using sofscale (Experimental quadrant A) and ultrasonic scaling (Experimental quadrant B), in three different quadrants. Case report forms were used to document the tooth sensitivity, soft tissue pain after scaling, patient preference of instrumentation, ease of calculus removal, patient comfort, soft tissue irritation, time taken for scaling, Bleeding while scaling, pre and post operative sulcus bleeding index. In addition to the clinical criteria, the teeth treated were extracted and evaluated using the scanning electron microscope to show potential effects on cemntal surfaces. No difference in tooth sensitivity was appreciated between control and experimental quadrant A. There was a higher degree of tooth sensitivity when treated with ultrasonic. Patients in control group appreciated a higher degree of soft tissue pain. Hand scaling using softscale produced a lesser amount of pain and treatment with ultrasoincs was the least painful. Most of the patients preferred ultrasonic scaling (70%) Calculus removal was easier. Hand scaling using sofscale gel results in more patient comfort when compared to hand scaling alone. There was no significant difference in patient comfort between handscaling using sofscale and ultrasonic scaling. The percentage of reduction of sulcus bleeding index showed no difference between the 3 scaling modalities SEM evaluation revealed that there was no significant difference the 3 scaling modalities in relation to residual calculus, cleaning efficiency and damage to the root surface. This study concluded that treatment with sofscale gel appears to be safe and effective method for removal calculus as this did not damage cemental surfaces, nor did it cause any damage to soft tissue. "Your tratar is your calcified hate. Not only the microflora in your oral cavity but also your muddled thoughts, your obstinate squinting backward, the way you regree when you mean to progress, in other words, the tendency of your diseased gums to form germ catching pockets, all that, the sum of dental picture and psyche, betrays you, it is stored up violence, full of murdero us designs" Gunter Grass.