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Biomedical subjects

J A Gliner

Publications and source records attributed to J A Gliner.

18 recordsLinked to original sources
PubMed1989

Internal and external validity in two studies that compared treatment methods.

Research comparing the effectiveness of two treatments offers both strengths and weaknesses for occupational therapy. Although it is worthwhile to determine which of two treatments works best for a particular problem, methodological problems may arise that preclude a valid conclusion. To draw valid conclusions from research, criteria for internal validity and external validity must be satisfied. The two preceding articles in this issue are examples of studies that used between-groups experimental methodology to compare the effectiveness of two different treatments. This paper evaluates the above-mentioned studies on the basis of principles of internal and external validity. One of these studies (Jongbloed, Stacey, & Brighton, 1989) was truly experimental, whereas the other study (Groves & Rider, 1989) was quasi-experimental. Results from both studies were similar because, in each study, both of the treatment groups improved, but there were no significant differences between treatments. Absence of a true control group in both studies presented limitations on the conclusion that both treatments worked equally well.

Analysis of Variance↗
PubMed1987

Bilateral hand performance with divided attention after a cerebral vascular accident.

A divided attention task was used with 10 left or right cerebral vascular accident (CVA) subjects who had return of functional movement in the affected extremities. The primary task was one subtest of the Jebson Hand Function Test. The secondary task was a foot press to a series of auditory cues. Four measurements were obtained for each subject at intervals of 1 month, 2 months, and 3 months after the stroke. Comparison scores on this procedure were also obtained on 5 normal subjects. The results indicated that dividing attention in the CVA subjects significantly decreased the performance on the primary task. The performance with the affected limb improved over the 3-month time period and reached a level of performance that was not significantly different from that of the unaffected limb for either the undivided or divided attention task. Implications for occupational therapy environments and consideration of attention limitations are discussed.

Aged↗
PubMed1985

Purposeful activity in motor learning theory: an event approach to motor skill acquisition.

This paper presents the event approach to motor skill acquisition as a theoretical treatment of the learning and relearning of motor skills; the emphasis is toward rehabilitation of physical dysfunction. Purposeful activity is viewed as a necessary prerequisite for the formation of coordinative structures, which are the bases for skilled movement. Traditional approaches to motor learning, which focus primarily on the actor, are seen as inadequate to accurately describe motor skill acquisition. The event approach treats the actor and the environment as inseparable in the acquisition of skills. Using this approach, I hope to establish a common ground and collaborative relationships between the disciplines of occupational therapy and motor learning.

Adult↗
PubMed1979

Visual evoked potentials and signal detection following a marathon race.

Five marathon runners participated in a visual sustained attention experiment 1 week prior to a competitive martathon race and from 1.5 to 8.5 h following the race. The task was designed to help assess changes in central nervous system function by examinining both behavioral deficits and electroencephalogram (EEG) visual evoked potentials as a function of the race. A significant increase in heart rate was observed during the behavioral task. No changes in any of the wave forms of the EEG visual evoked response were observed during the vigilance task as a function of the race. Sustained visual attention responses were unchanged for correct detections, but post-marathon performance gave significantly fewer false positive responses. The results provided evidence that central nervous system dysfunction was not observed following the completion of a competitive marathon race.

Adult↗
PubMed1979

Pulmonary function and maximum exercise responses following acute ozone exposure.

We examined changes in pulmonary function during resting exposure to concentrations of ozone at 0.75, 0.50, 0.25, and 0.00 parts/million (ppm), and determined the effect these exposures had on a subsequent maximum exercise test using filtered air. In order to determine if recovery of pulmonary function would be facilitated by increased ventilation due to maximum exercise, a control condition was conducted with subjects resting for a period equivalent to the maximum exercise condition. Eight males and five females participated in eight different conditions in order to answer these two questions. Resting 2-h exposure to 0.75 and 0.50 ppm ozone caused significant decrements in forced vital capacity of 10% and 5%, respectively. However, 0.00 and 0.25 ppm ozone induced no pulmonary decrement. None of the pollutant conditions reduced subsequent maximum exercise performance (ml O2.min-1.kg-1, heart rate, and total performance time). The pulmonary function responses after the maximum capacity test returned to pre-ozone values for the 0.50 ppm condition, but were still significantly decreased for the 0.75 ppm condition. The increased ventilatory exchanges from maximum exercise did not facilitate the return of pulmonary function. It appeared that increased ventilation during ozone exposure plays a significant role only in inducing pulmonary function decrement, but not in facilitating the return of pulmonary function to normal values.

Adult↗
PubMed1979

Auditory and visual sustained attention during ozone exposure.

Experiments were conducted to determine the effects of different concentrations of ozone at 0.00, 0.25, 0.50, and 0.75 parts/million (ppm) on sustained visual and auditory attention tasks (vigilance performance). When the rate of signals to nonsignals was low, approximately 1 out of 30, ozone in concentrations as high as 0.75 ppm did not alter performance to either visual or auditory tasks. However, when the ratio of signals to non-signals was increased, a deficit in performance beyond that of the normal vigilance decline was observed during the 0.75 ppm ozone exposure. However, no changes in false positive responses occurred. The results were interpreted within the framework of an arousal hypothesis, suggesting that high concentrations of ozone may produce overarousal.

Adult↗
PubMed1977

Influence of exercise and heat stress on pulmonary function during ozone exposure.

We studied the effects of a 2-h exposure to ozone (0.5 ppm) in 14 nonsmoking males under four environmental conditions (WBGT (wet bulb-globe temperature index) = 64.4, 80.0, 85.2, and 92.0 degrees F). The subjects were divided into two groups, A (n = 8) and B (n = 6). Thirty minutes of exercise at 40% Vo2 max was performed from 60 to 90 min for group A and 30 to 60 min for group B. Pulmonary function changes, determined throughout exposure, were greatest immediately after exercise in both groups. Few changes occurred before the exercise period. However, the decrease in FVC (826 ml) and FEV1.0 (937 ml) following exercise was more than twice as large as the decrement seen at end exosure (388 and 423 ml, respectively). Measures of maximum expiratory flow (FEF 25-75%, FEF 50% FEF 75%) showed similar reductions. In many cases, reversal of these changes occurred during the remainder of the exposure period. The greatest decrease in FVC occurred when heat and ozone exposures were combined (WBGT = 92.0 degrees F). We conclude that the effects of ozone are most severe immediately after exercise and that heat stress may modify the overall effect of ozone on pulmonary function.

Adult↗
PubMed1977

Effects of three kinds of hypoxias on vigilance performance.

The consequences for vigilance performance of inhaling carbon monoxide at altitude were examined. In addition, the effects of altitude and CO at an equivalent reduction in O2-carrying capacity were compared. Ten subjects performed a visual vigilance task under four atmospheric conditions. Physiological measures included heart rate, blood pressure, and ventilation. Blood hemoglobin and CO levels were measured directly from blood samples drawn after 0,50 and 120 min of exposure. The physiological variables measured and subjective responses of subjects showed no changes attributable to the atmospheric conditions. A statistically significant change in vigilance performance as measured by precentage of signals detected, was found between control and low oxygen; however, performance under CO and the combination of CO and low oxygen was not different from control. The lack of deterioration in performance under the combination of CO and low oxygen suggested that the increased severity of the stress resulted in activation of compensatory mechanisms which counterbalanced the decreased O2 available to the tissues.

Adult↗
PubMed1976

Oxygen uptake measurements during competitive marathon running.

Oxygen uptakes and running speeds of two marathon runners as well as average slopes of the running terrain were measured approximately every 3 miles of a competitive marathon. The runners had energy expenditures requiring from 68 to 100% of their Vo2 max, confirming previous estimates. As the race progressed, both runners exhibited decreases in V92 while running at similar rates and slopes. At 23.4 miles, one runner was found to be utilizing 4.54 l/min, a value equivalent to his Vo2 max.

Humans↗
PubMed1975

Operant conditioning of heart rate in curarized rats: hemodynamic changes.

Three groups of curarized rats were subjected to operant heart rate conditioning with use of a shock-avoidance procedure while cardiac output, mean arterial pressure, and total peripheral resistance were measured. Heart rate changes in the control group remained constant during the entire 90-min experimental period, while cardiac output decreased significantly. Those rats that were reinforced for increasing their heart rate had a small but statistically significant increase in heart rate, but cardiac output decreased to approximately the same extent as in the control group. The group reinforced for decreasing their heart rate demonstrated a large, significant decrease in heart rate and an even larger drop in cardiac output, which was significantly greater than that of either of the other two groups. Operant conditioning of a single facet of the cardiovascular system resulted in significantly larger changes in other cardiovascular parameters, which may have been partly masked by the physiological effects of d-tubocurarine. Therefore, only when these other measures of cardiovascular function are taken into consideration can interpretation of operant heart rate conditioning become meaningful.

Animals↗
PubMed1975

Man's physiologic response to long-term work during thermal and pollutant stress.

Metabolic, temperature, and cardiorespiratory responses of 19 healthy males, age range 18-30 yr for one group and 40-55 yr for another, were studied during 210 minutes submaximal work at 35% Vo2 max. The subjects were exposed to four different pollutant gas mixtures at two different temperatures, 25 degrees C and 35 degrees C (relative humidity 30%). The four gas mixtures were filtered air (FA), 50 ppm carbon monoxide in filtered air (CO), 0.24 ppm peroxyacetyl nitrate in filtered air (PAN), and a combination of all three mixtures (PANCO). In the CO exposure, the heart rate was significantly greater than that observed during FA conditions (P less than 0.05). Metabolic and thermoregulatory responses to long-term work were not different in the various pollutant environments. Significant decreases in stroke volume and increases in heart rate were observed during the course of the 25 degrees C exposures with no alteration in cardiac output. Heart rates were higher during 35 degrees C exposures while cardiac output remained at the same level with a consequent further reduction in stroke output.

Adolescent↗