Biomedical subjects
R Kerr
Publications and source records attributed to R Kerr.
Diffuse idiopathic skeletal hyperostosis (DISH).
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Motor skill acquisition by individuals with Down syndrome.
Motor skill acquisition of subjects with Down syndrome on a pursuit tracking task was assessed in comparison to groups of mentally retarded subjects without Down syndrome and nonretarded subjects matched for functional age and chronological age (CA). Thirty-seven male subjects performed eight trials on a subject-paced pursuit tracking task. The main finding was that subjects with Down syndrome did not respond to directional probability in the same manner shown by the retarded or the nonretarded subjects matched for CA or functional age. This difference in strategy was also reflected in their greater emphasis on accuracy rather than speed. Finally, these effects were consistent across the subjects with Down syndrome despite the large intersubject variability seen in their performance.
Radiology of the seronegative spondyloarthropathies.
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Degenerative diseases of the spine.
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Angelchik anti-reflux device: radiographic appearance of complications.
The authors report 8 cases of erosion of an Angelchik anti-reflux prosthesis into the stomach. Erosion is detected by the appearance of the smooth contour of the device in the stomach. One device migrated distally.
Digital arthrography of the wrist: a radiographic-pathologic investigation.
An analysis of digital arthrography of the wrist was accomplished in 10 cadaveric specimens. In each case, images were obtained during a 30-sec period in which a small amount of contrast material was introduced into the radiocarpal compartment; films were reviewed with and without subtraction technique. Pathologic examination of the sectioned specimens documented the accuracy of this arthrographic method. The sequence of contrast opacification of the various compartments of the wrist and the location and size of the defects within ligamentous and cartilaginous structures were ideally seen with digital arthrography. A previously unemphasized pattern of communication, that between the midcarpal and pisiform-triquetral compartments, was seen in two instances. Digital wrist arthrography seems to represent an excellent method to evaluate the patient with suspected soft-tissue injury.
Complications of the Angelchik antireflux prosthesis.
Various complications have been reported recently for the Angelchik antireflux prosthesis, a silicone-gel prosthesis used in the treatment of gastroesophageal reflux and associated hiatal hernia. We have studied the cases of 11 patients with complications of this prosthesis and have reviewed the literature for others. Complications included 8 erosions of the device into the gastrointestinal tract, 1 migration, 1 improper placement, and 1 case believed to be surgical trauma. These complications represent those typical to reflux surgery and some unique to the Angelchik prosthesis (migration and erosion). The exact frequency is unknown, with the manufacturer estimating migration at 0.81% and erosion at 0.15%. Available data indicate that complications may occur up to several years after implantation, and physicians may not recognize the problems with the prosthesis if they are unaware of the complications.
Communication through physical activity for learning disabled children.
To measure the extent to which an integrated program of motor and cognitive tasks might enhance the learning disabled children's motor and basic cognitive skills, a treated group of 8 had three 1/2-hr. sessions per week for 6 mo. 8 control subjects continued regular physical education and reading programs with their classroom teacher. All subjects were tested before and after 6 mo. Over-all the treated group showed greater improvement on tests of both motor and cognitive skills than the control group. This study suggests a physical activity program can influence basic cognitive skills as well as motor skills.
Practice variability and longer and short retention intervals.
This experiment compared the effect of different practice schedules on distance and direction errors in a blindfolded two-dimensional movement. The three experimental groups, (a) criterion target only, (b) varied targets (not criterion), (c) single target (not criterion) and one control group (rested), were tested immediately after the "practice" session without knowledge of results and were tested again after a 1-wk. retention interval. The distance data demonstrated little difference among the three experimental groups, but all three groups were significantly better than the control group. However, there was little difference in errors of direction among the groups. While the data for distance support a schema interpretation of movement control, the data for direction appear to reflect the concept of a visual-spatial map being used to guide movements.
Diving, adaptation, and Fitts law.
To assess Welford's dual controlling factor interpretation of Fitts' law, 20 scuba divers performed a reciprocal tapping task. In an attempt to separate the two factors, the subjects were tested on land and underwater. This does not change the basic parameters of the task but does put the subjects under informational stress, in that underwater the movement is less ballistic in nature and should require the processing of more information (feedback) in each tap. On land, the contributions of movement amplitude and precision were approximately equal. However, the relative changes in contribution of these factors to movement time underwater suggests that these parameters do in fact represent separate controlling factors.
Specific and varied practice of motor skill.
To assess the potential effect of specific and varied practice on the development of motor schema, 64 children in two age groups (8 yr. and 12 yr.) were tested on a simple throwing task at the beginning and end of a 12-wk. physical education program. For the throwing test the children were assigned to either a specificity or a schema group (varied practice). The task was performed without visual feedback, but knowledge of results was given after each trial. Prior to both tests at the criterion target, the specific group was given practice throws using the criterion target distance, whereas the schema group practiced on two other targets. No differences were found between the two groups at the beginning of the program but on the posttest those children receiving a variety of practice on the throwing task performed significantly better than the specific-practice group. Thus it was suggested that a varied practice schedule may facilitate the initial formation of motor schema, and this process may be enhanced by participation in a physical education program.
The effects of prolonged coffee intake on genetically identical mice.
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Movement control and maturation in elementary-grade children.
Serial tapping by 5-, 7- and 9-yr.-old boys and girls, as measured by Fitts' Law, was recorded. 60 Ss performed a reciprocal tapping task and were assessed developmentally via hand-wrist X-rays. No significant relationship was found between the fine motor task and skeletal age. The results of the motor task suggest an improvement in movement time, with age, due to an ability to plan subsequent movements rather than simply an increase in speed of arm movement.
Cell proliferation during the development of stress erosions in mouse stomach.
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Digital arthrography in the evaluation of painful joint prostheses.
Digital arthrography was accomplished in 16 patients who had painful prostheses. In each instance, resulting arthrographic abnormalities were compared with those apparent on subsequent overhead radiographs. Results indicate the potential value of the digital technique in this clinical setting. The examination is easy to perform and rapid, and allows the examiner to view the changing images in the subtraction mode. Image manipulation and enhancement are also possible.
CT analysis of proximal femoral trabecular pattern simulating skeletal pathology.
The proximal femoral trabecular pattern was studied in 20 patients, six cadavers, and 20 macerated specimens using plain film radiography and CT. A distinctive pattern of increased radiodensity in the proximal femur is described in patients and specimens with osteoporosis and osteoarthritis. The appearance is similar to that of an enchondroma or bone infarct. This pattern may be explained by biomechanical principles and is created by unmasking or hypertrophy of preexistent, reinforcing trabeculae. Confusion with osseous pathology can be avoided if the radiologist is aware of this pattern.