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Biomedical subjects

W O Thompson

Publications and source records attributed to W O Thompson.

86 records · Page 5Linked to original sources
PubMedDate not supplied

Effects of scopolamine on visual evoked potentials in aging and dementia.

The unusual combination of a normal pattern reversal VEP and a delayed flash VEP has been reported in patients with dementia of Alzheimer's type (DAT). Hyoscine hydrobromide has been reported to produce a similar VEP abnormality in young, healthy subjects. In the present study, we assessed the relative sensitivity of DAT patients and healthy young, middle-aged and elderly subjects to temporary cholinergic blockade. We report VEP latency values following 3 doses of scopolamine and after a peripheral anticholinergic agent. Flash P2 latency was not significantly slower in DAT patients than in the healthy elderly. Scopolamine increased P2 latency in the young controls but did not affect any other group. The pattern reversal P100 was normal in DAT, and a significant increase in latency occurred following scopolamine administration in both the control and patient groups.

Adult↗
PubMedDate not supplied

Children's dietary recalls: the salience of entree and liking for foods on accuracy and order of reporting.

This study investigated the impact of entree and liking for foods on the accuracy and order of reporting on children's school lunch recalls. Data were collected during a series of studies to investigate children's lunch recalls from a cognitive processing approach to understand better how children remember what they have eaten. Fourth-grade children from four schools were randomly selected, observed eating lunch, and interviewed the same (n = 89) or next (n = 148) day. Foods were classified as matches (observed and reported eaten), omissions (observed but not reported eaten), or phantoms (not observed but reported eaten), and corresponding rates were calculated. Statistical analyses included z tests and permutation tests. For same- and next-day recalls, children were more likely to report entree than other meal components earlier in the interview. For next-day recalls, the phantom rate for the remaining items was lower for children who reported entrees accurately versus inaccurately. For items liked "a lot" compared with items "not liked a lot," match rates were higher for next-day recalls, and phantom rates were lower for both same- and next-day recalls. Because entree and liking for foods appear to play salient roles in children's dietary recalls, these results provide guidance regarding the development of specific prompts to increase the accuracy of children's dietary recalls.

Child↗
PubMedDate not supplied

Shoulder muscle forces and tendon excursions during glenohumeral abduction in the scapular plane.

Muscle force values and tendon excursions across the glenohumeral joint during unconstrained glenohumeral abduction in the scapular plane were evaluated with a dynamic shoulder testing apparatus. This evaluation was achieved by simulated rotator cuff and middle deltoid activity applied in four plausible muscle force ratios: (1) equal force to each tendon, (2) 2:3 ratio of force applied to the middle deltoid/supraspinatus tendons, (3) 3:2 ratio of force applied to the middle deltoid/supraspinatus tendons, and (4) zero force applied to the supraspinatus tendon to simulate supraspinatus paralysis. The glenohumeral joint was then moved to 5 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees, and maximum glenohumeral abduction while muscle forces, tendon excursions, and glenohumeral joint kinematics were monitored. Full glenohumeral abduction was achieved in all four test conditions. When the muscle force combination favored the middle deltoid, the smallest supraspinatus force was required from 30 degrees to maximum glenohumeral abduction; however, when the supraspinatus was favored, the largest supraspinatus force was necessary to achieve maximum glenohumeral abduction. With simulated supraspinatus paralysis the middle deltoid required the greatest increase in force from 15 degrees through 45 degrees of glenohumeral abduction. These results indicate that muscle efficiency during glenohumeral abduction is highly dependent on the ratio of applied force between the middle deltoid and supraspinatus. A larger contribution of force from the supraspinatus was required near the beginning of motion, whereas the middle deltoid was more important near the end of glenohumeral abduction in the scapular plane. Tendon excursion for the middle deltoid (6.4 +/- 0.2 cm) and supraspinatus (3.8 +/- 0.2 cm) were proportionately larger than those for the subscapularis and infraspinatus. Humeral head translations on the glenoid were less than 2 mm in all four conditions evaluated; therefore the glenohumeral joint behaves kinematically as a "ball-and-socket" articulation during glenohumeral abduction. Simulated supraspinatus paralysis does not change normal joint kinematics and does not prevent full glenohumeral abduction.

Aged↗
PubMedDate not supplied

Tibial meniscal dynamics using three-dimensional reconstruction of magnetic resonance images.

The human knee joint represents a complex biomechanical system of which the menisci are an integral component. At present, little data exists describing the meniscal kinematics of the intact knee. Accordingly, a three-dimensional reconstruction magnetic resonance image model was used to explore this issue. Five fresh cadaveric knees were examined by magnetic resonance imaging throughout a full range of motion at 10 degrees intervals. Computer three-dimensional images of the menisci were generated and evaluated for anteroposterior excursion and deformation. During flexion, the posterior excursion of the medial meniscus was 5.1 mm, while that of the lateral meniscus was 11.2 mm. The anterior horn segments were shown to be more mobile than the posterior horn segments bilaterally. Prior limitations of meniscal kinematic assessment may be overcome with advanced imaging techniques such as magnetic resonance imaging and three-dimensional reconstruction. The menisci are highly mobile and easily deformed structures within the intact, cadaveric knee. This imaging technique may prove useful in the elucidation of meniscal dynamics. In the future, similar techniques may be applied clinically to aid in the diagnosis of joint dysfunction.

Biomechanical Phenomena↗
PubMedDate not supplied

A biomechanical analysis of rotator cuff deficiency in a cadaveric model.

We conducted this cadaveric study to define a biomechanical rationale for rotator cuff function in several deficiency states. A dynamic shoulder testing apparatus was used to examine change in middle deltoid muscle force and humeral translation associated with simulated rotator cuff tendon paralyses and various sizes of rotator cuff tears. Supraspinatus paralysis resulted in a significant increase (101%) in the middle deltoid force required to initiate abduction. This increase diminished to only 12% for full glenohumeral abduction. The glenohumeral joint maintained ball-and-socket kinematics during glenohumeral abduction in the scapular plane with an intact rotator cuff. No significant alterations in humeral translation occurred with a simulated supraspinatus paralysis, nor with 1-, 3-, and 5-cm rotator cuff tears, provided the infraspinatus tendon was functional. Global tears resulted in an inability to elevate beyond 25 degrees of glenohumeral abduction despite a threefold increase in middle deltoid force. These results validated the importance of the supraspinatus tendon during the initiation of abduction. Glenohumeral joint motion was not affected when the "transverse force couple" (subscapularis, infraspinatus, and teres minor tendons) remained intact. Significant changes in glenohumeral joint motion occurred only if paralysis or anatomic deficiency violated this force couple. Finally, this model confirmed that rotator cuff disease treatment must address function in addition to anatomy.

Aged↗
PubMedDate not supplied

Comparing treatment options for occlusal surfaces utilizing an invasive index.

The purpose of this project was to develop an invasive index to: 1) compare the treatments recommended by dentists for the occlusal surfaces of molars; 2) compare the invasive index score of each tooth with the extent of the carious lesion as determined by electrical resistance and histological examination; and 3) compare the relative extent of the total crown destruction resulting from the carious lesion and the cavity preparation. Twenty dentists examined 19 extracted permanent molar teeth using a #23 explorer and selected the most appropriate treatment from the following options: no treatment (score 0), occlusal sealant (score 1), preventive resin (score 2), occlusal amalgam (score 3). The invasive index scores determined for each dentist and each tooth were compared using an analysis of variance. The electrical conductivity of each tooth was measured with an electronic caries detector (Vanguard). Electrical resistance scores were compared to the invasive index scores and to a histological examination. The results demonstrate that the invasive index is a useful means to compare treatments recommended by different dentists. The invasive index suggests there is considerable variation among dentists in the treatment they recommend for occlusal surfaces. Electrical resistance testing did not provide helpful information for treatment planning of questionably carious occlusal surfaces.

Adolescent↗
PubMedDate not supplied

Radiographic recommendations for the primary dentition: comparison of general dentists and pediatric dentists.

A survey which included brief case histories and intraoral photos of four primary dentitions ranging from healthy to severely carious was mailed to a random sample of 2000 general dentists and 1000 pediatric dentists. Radiographic options were listed, from which the dentist was to indicate all films needed for each child's examination. Surveys were received from 1273 (43%) dentists, including 713 (36%) general dentists and 560 (56%) pediatric dentists. The pediatric dentists recommended significantly more diagnostic radiographs than did the general dentists across all four primary dentition cases. This trend was apparent in the absence of clinically visible caries. When radiographs were recommended, bite-wing radiographs were the most frequently ordered films. The most frequently ordered combination among all respondents was bite-wing radiographs plus anterior periapical films. The results suggest that, frequently, neither general dentists nor pediatric dentists prescribe radiographs for the primary dentition patient that conform to the USDHHS guidelines for radiographic examination (1987).

Child↗
PubMedDate not supplied

Radiographic recommendations for the transitional dentition: comparison of general dentists and pediatric dentists.

A survey which included brief case histories and intraoral photos of four transitional dentitions, including examples of ectopic and delayed eruption, as well as carious lesions, was mailed to a random sample of 2000 general dentists and 1000 pediatric dentists. Radiographic options were listed, from which each dentist was to indicate all films needed for each child's examination. Surveys were returned by 1273 (43%) dentists, including 713 (36%) general dentists and 560 (56%) pediatric dentists. The pediatric dentists took significantly more diagnostic radiographs than did the general dentists for each of the four transitional dentition cases. Pediatric dentists were more likely than the general dentists to take panoramic films and combinations which included panoramic films, bite-wing radiographs and periapical films. The most frequently ordered combinations were bite-wing radiographs plus panoramic films and bite-wing radiographs plus anterior periapical films. General dentists recommended bite-wing radiographs films only more frequently than did pediatric dentists. In view of the results of this study and the USDHHS guidelines for radiographic examinations, (1987) education must be provided for both general dentists and pediatric dentists regarding appropriate radiographic examinations for transitional dentition patients.

Child↗
PubMedDate not supplied

Use of verbal descriptors, thermal scores and electrical pulp testing as predictors of tooth pain before and after application of benzocaine gels into cavities of teeth with pulpitis.

A double-blind pilot study was conducted on 27 consenting human volunteers who had irreversible pulpitis associated with persistent toothache pain from open carious lesions. Formulations tested contained either 0, 10%, or 20% benzocaine and were identified only by a numbered code. Before the experiment started, a small amount of a known 5% benzocaine gel was placed for 1 minute on the tongue of each patient to assure a sensation of numbness within the oral cavity. Then the test tooth was washed with a gentle stream of warm water and dried with gauze. A randomly selected test medication was placed into the open cavity and around the gingival margins for 5 minutes. Pre- and posttreatment tests were conducted at the following timed intervals: 0, 5, 15, 30, 45, 60, 75 and 90 minutes. The tests included degree of pain (rated: 0 = none, 1 = mild, 2 = moderate, 3 = severe); electrical pulp testing (EPT) by a modified, voltage-ramping instrument; and ice water testing (0.5 mL directed quickly onto sound enamel of the tooth and rated: 0 to 4, with 4 being intolerable). After testing, or when pain returned to baseline, endodontic procedures were performed. There was a significant increase (p < 0.032, Fisher exact test) in subjects obtaining pain relief, rated by verbal descriptors, from the benzocaine gels (14 out of 18 improved) compared to placebo (3 out of 9 improved). It was concluded that: 1) benzocaine gels are effective formulations for temporary relief of toothache pain, 2) there were no statistical differences in EPT scores between teeth having pulpitis and control teeth, 3) there were no correlations between direction of EPT scores and pain relief, 4) cold water testing was a good predictor of whether or not a tooth had pulpitis, and 5) changes in cold water testing scores after treatment could not be correlated to relief of pain according to verbal descriptors. The effectiveness of benzocaine in relieving toothache pain verifies previous studies; however, a difference between 10% and 20% benzocaine could not be demonstrated probably because of two factors: 1) the present experiment had a small sample size, and 2) there was no direct measurement of duration of local anesthesia.

Adult↗
PubMedDate not supplied

Validity of the Creasy risk appraisal instrument for prediction of preterm labor.

The study objectives were twofold: (a) retrospective evaluation of the predictive validity of the Creasy in a cross-cultural urban and rural population based on the outcome data of publicly served prenatal patients, and (b) examination of the universality of the Creasy through comparison of the predictive validity found in the study population with other published results. Subjects were 433 white and African American women who entered prenatal services through 1 urban and 12 rural health department sites and received care in a regionalized system in East Central Georgia. The Creasy instrument was administered once to all prenatal women in their initial clinical encounters. The instrument identified 30.47% of the women who experienced preterm deliveries. Only 44.3% of the time did a score indicating high risk for preterm delivery accurately predict preterm delivery. Predictive validity for rural and urban subjects was not significantly different. As predictive validity for the Creasy was low, it was determined that it has limited clinical usefulness with a single administration. Usefulness may be improved with further risk-factor specification and frequent measurement throughout pregnancy.

Adolescent↗