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Biomedical subjects

D R McIntyre

Publications and source records attributed to D R McIntyre.

At least 19 recordsLinked to original sources
PubMed1997

Classification of low back pain from dynamic motion characteristics using an artificial neural network.

STUDY DESIGN: Data were collected from 183 subjects who were randomly assigned to the training and test groups. During testing of the classification system, knowledge of the low back pain condition or motion characteristics of the patients in the test group was not made available to the system. OBJECTIVES: To determine specific characteristics of trunk motion associated with different categories of spinal disorders and to determine whether a neural network analysis system can be effective in distinguishing patterns. SUMMARY OF BACKGROUND DATA: Numerous studies have established the difficulty of evaluating lower back pain. Imaging techniques are expensive and ineffective in many cases. A technique for evaluation of lower back pain was developed on the basis of analysis of such dynamic motion features as shape, velocity, and symmetry of movements, using a neural network classification system. METHODS: Dynamic motion data were collected from 183 subjects using a triaxial goniometer. Features of the movement were extracted and provided as input to a two-stage neural network classifier governed by a radial basis function architecture. After training, the output of the classifier was compared with Québec Task Force pain classifications obtained for the patients. Linear and nonlinear classification techniques were compared. RESULTS: The system could determine low back pain classification from motion characteristics. The neural network classifier produced the best results with up to 85% accuracy on novel "validation" data. CONCLUSIONS: A neural network based on kinematic data is an excellent predictive model for classification of lower back pain. Such a system could markedly improve the management of lower back pain in the individual patient.

Adult↗
PubMed1996

Study provides new evidence of back belts' effectiveness.

A major new study conducted by the UCLA School of Public Health has bolstered the claim that back support devices reduce low-back injuries. The study involved nearly 36,000 employees at Home Depot stores in California who logged 101 million work hours from 1989 through 1994. The company implemented mandatory wearing of belts in early 1990, and the study's authors reported that the workers' rate of acute low back injuries fell from 30.6 per million hours before implementation to 20.2 per million hours. UCLA Professor of Epidemiology Jess F. Kraus, the study's lead author, told The Wall Street Journal. "The study found a pretty big effect with a simple countermeasure. It is pretty hard to argue that it is a chance phenomenon." Kraus, who is the director of UCLA's Southern California injury Prevention Research Center, began his research by visiting 30 Home Depot stores to see whether employees were wearing the belts consistently. Compliance with the mandatory policy was quite high overall-above 98 percent, as calculated during an unannounced walk-through of all 77 stores in late 1993 and early 1994, according to the study. Back support manufactures hailed the Home Depot study as the largest long-term epidemiological study yet undertaken of the supports. It is proof, they said, that back supports are effective personal protective equipment-a contention at odds with the position of NIOSH the National institute for Occupational Safety and Health. In 1994, NIOSH reviewed the scientific literature and concluded there was not enough evidence to recommend that the supports be worn by uninjured workers. Sales plunged after NIOSH released its findings, according to the manufactures. The UCLA researchers found that low-back injuries declined in workers of both sexes, in younger workers as well as those older than 55, and among those with low levels of lifting as well as those with higher levels. The researchers concluded that mandatory use of back supports significantly reduces acute low-back work injuries. Low-back injuries account for one-fourth of all workers' compensation claims paid by U.S. employers-$11 billion in 1990 alone. NIOSH's ergonomic coordinator, Lawrence Fine, told The Journal, "for many companies this is the largest health and safety issue they are wrestling with." NIOSH has embarked on its own, smaller study of back supports' effectiveness among Wal-Mart workers.

Adult↗
PubMed1993

Secondary axes activity of normal subjects and low back pain patients.

The purpose of this study was to compare the secondary axes activity of normal subjects and low back pain patients. Each subject performed maximum isometric trials in all six primary directions. This was followed by five dynamic repetitions in each of the cardinal planes against relative resistances set at 50% of the recorded maximum isometric torques for each axis. The results showed that for all movement axes the secondary axes torques were significantly less (p = 0.01-0.001) for low back pain patients compared to normal subjects. The secondary axes torques were generally weakly related to an individual's ability to both generate maximum isometric torques about the same axis and the primary axes maximum velocities.

Adult↗
PubMed1991

A comparison of the characteristics of preferred low-back motion of normal subjects and low-back-pain patients.

The purpose of this study was to compare the preferred low-back motion of normal subjects and low-back-pain patients. Each subject performed a maximum isometric flexion trial followed by repeated flexion and extension against a relative resistance set at 50% of the recorded maximum flexion isometric torque. The subjects were instructed to move at their own pace through their preferred movement range until either exhaustion or for 120s. The results showed that the groups differed significantly in their preferred motion characteristics, although the performances were equally consistent.

Adult↗
PubMed1990

The characteristics of preferred low-back motion.

The purposes of this study were to identify the loading effects on preferred low-back motion and to determine the consistency of preferred low-back motion. Fifteen male and female volunteers served as subjects. Each subject performed four trials of repeated flexion and extension until either the subject became exhausted or for 120s. Each trial corresponded to a relative load of 0, 25, 50, and 75% of the subject's prerecorded maximum torque in isometric flexion. The subjects were instructed to perform the movements at their own pace and through their preferred movement range. The results showed that above the 25% resistance level, the increased loads were accompanied by decreased velocities, with the changes due to the cycle temporal characteristics. The increased loads also resulted in decreased cycle excursions, with these changes due to reductions in the extension endpoints. With increased resistances the descriptive parameters became more variable, with a trend of increased variability toward the latter portion of a trial.

Adult↗
PubMed1989

Incidence of microscopically detectable degenerative characteristics in skeletal muscle of turkey.

1. The incidence of microscopically detectable degenerative characteristics in 5 skeletal muscles (m. pectoralis thoracicus, m. supracoracoideus, m. biceps femoris, m. semitendinosus, m. femorotibialis medius) of turkeys was investigated. 2. Samples were obtained from 30 Large White turkey males 14, 16 and 18 weeks old. Hyaline degeneration, infiltration of mononuclear cells and necrotic fibres were observed. 3. Individual fibres varied greatly in size and muscle fibre nuclei were often shrunken and pyknotic. 4. Weak and/or uniform reaction for Ca++-ATPase and SDH in all types of muscle fibres and loss of alkaline phosphatase activity in cell membranes were noted. A positive reaction for acid phosphatase occurred in regions of perivascular infiltration and in necrotic muscle fibres. The majority of muscle fibres possessed high activity for phosphorylase a and b. 5. Based on the use of fluorescein alpha-bungarotoxin conjugate, motor end-plates appeared to be morphologically intact. Direct immunofluorescence with anti-chicken IgG showed positive reaction in muscle fibres undergoing necrosis and in the involved connective tissue. 6. Degenerative changes varied with age and were most marked in the oldest birds. 7. Because gross degenerative symptoms were absent from both the birds and the meat from them, the condition appears to be either different from or a precursor to the degenerative myopathy characterised by other authors.

Aging↗
PubMed1989

The stability of isometric trunk flexion measurements.

The purpose of this study was to determine (a) the number of isometric trunk flexions needed to obtain a stable measure of exertion, (b) the least variable parameter to be used to quantify maximum isometric trunk flexion, and (c) the time interval needed to obtain the least variable measure of maximum isometric flexion. Ten adult males served as subjects. Each subject performed five trials of one maximum isometric trunk flexion. Each trial lasted for 5 s. The results showed (a) only one trial is required to obtain a stable measure of the maximum torque generated during isometric flexion, (b) more than one trial is required to obtain a stable measure of the average torques, (c) maximum torques are more stable measures than average torques, (d) the first second of a 5-s exertion does not yield stable measurements, and (e) individuals adopt different exertion strategies during each trial.

Adult↗
PubMed1986

Effect of sperm numbers per insemination following early or late initial inseminations in turkeys.

Large White turkey hens were used in this study to investigate sperm storage in the hen throughout a 20-week breeding cycle. Hens were initially inseminated early or late and subsequently at 7-day intervals with either 20, 50, or 100 million sperm each time. Early inseminations (EI) were performed on Days 14 and 17 postlighting, and the late inseminations (LI) were performed on Days 21 and 24 postlighting. Fertility (percent) was calculated weekly for 20 weeks following the second initial insemination in each group. Fertility was greatest in EI hens for the 20-week period; the largest difference occurred between EI and LI treatments of the 50 million sperm/insemination group. A significant interaction was observed between time of initial insemination and sperm numbers per insemination. Overall fertility was improved with each increase in sperm numbers/insemination.

Animals↗
PubMed1985

Effect of initial insemination and insemination interval on fertility in turkey hens.

Large White turkey hens were used to observe fertility through a 20-week laying cycle (31 to 51 weeks of age), following early initial inseminations (EI) and late initial inseminations (LI). Early initial inseminations were made on Days 13 and 15 following photostimulation with subsequent artificial insemination (AI) every 7 (EI + 7) or 14 (EI + 14) days. Late initial inseminations were made on Days 20 and 22 postlighting with subsequent AI every 7 (LI + 7) or 14 (LI + 14) days. Percent of egg production, fertility, and hatch of fertile eggs were measured following the initial AI in each treatment. No significant differences in egg production were seen between treatments. Percent of fertility was greatest in Weeks 6 to 20 with 7-day AI intervals as compared to 14-day intervals. Early inseminations resulted in higher fertility than LI with 14-day AI intervals, but no difference was observed with 7-day intervals. Greater fertility in EI + 14 hens through 20 weeks of egg production, as compared to LI + 14 hens, seems to lend further support to the concept of enhanced oviduct receptiveness to spermatozoa before egg production commences.

Animals↗
PubMed1983

Filling rates of the uterovaginal sperm storage glands in the turkey.

Large White turkey hens were assigned to two groups of 30 birds each and photostimulated at 32 weeks of age. Group 1 hens (nonlaying) were artificially inseminated (AI) three times prior to the onset of lay on Days 14, 15, and 16 postlighting. Group 2 hens (laying) were also inseminated three times as in Group 1, but the inseminations followed the onset of egg production on Days 23, 24, and 25 postlighting. Six hens from each group were sacrificed following the initial insemination at intervals of 1, 2, 3, 5, and 7 days. Histological sections of the uterovaginal (UV) junction from each hen were made to determine filling rates of the sperm storage glands. Sperm concentrations in the UV glands of the nonlaying hens did not increase significantly beyond 24 hr post-AI. There was a significant (P less than .05) peak, however, in the number of stored spermatozoa on Day 5 post-AI in the laying hens. These results indicate that inseminations performed in the absence of oviposition and ovulation enable the UV sperm storage glands to be filled nearer their capacity with fewer inseminations.

Animals↗
PubMed1982

Fertility of the turkey hen as affected by initial insemination and onset of egg production.

A comparison between initial inseminations of Large White turkey hens prior to or after onset of egg production was undertaken to determine the effect on fertility. Semen from Bronze toms was utilized for the initial inseminations whereas all subsequent inseminations utilized White sires. After 10 weeks there were no significant differences between treatments for percent egg production or hatchability. Inseminating prior to the onset of egg production resulted in a significantly different (P less than or equal to .05) 8-week average of 97.5% fertility in the early insemination (EI) group as compared to an average of 90.4% in the late insemination (LI) group. Differences between the EI and the LI groups were greatest during the last 2 weeks of the experiment during which the EI hens maintained higher levels of fertility. Bronze poults were observed in the EI progeny following three subsequent inseminations with semen from White sires, whereas no Bronze poults were obtained from the LI hens following the third subsequent insemination with White semen.

Animals↗