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R H Gabel

Publications and source records attributed to R H Gabel.

16 recordsLinked to original sources
PubMed1997

Popliteus function in ACL-deficient patients.

Anterior cruciate ligament (ACL) injuries commonly result in anterolateral rotary instability and a 'pivot shift' phenomenon. Since popliteus muscle stimulation causes a pivot shift, some postulate the popliteus muscle plays a role in causing pivot shifts. To see if patients with pivot shifts exhibited excessive popliteus muscle activity, we studied fine-wire EMGs of the popliteus in 16 normal subjects and 10 ACL-deficient subjects. Subjects performed six activities (level walking and jogging, ascending walking and jogging, and descending walking and jogging). Except for minor timing differences in ascending treadmill and ascending jogging, the signals were similar for injured and uninjured limbs; similar variance ratios suggested similar pattern variability. Thus, we observed only minor popliteus EMG signal differences in this group of patients. We conclude that the popliteus muscle does not actively contribute to instability in the studied activities.

Anterior Cruciate Ligament Injuries↗
PubMed1994

The effects of signal conditioning on the statistical analyses of gait EMG.

Ensemble averaged EMG profiles generated for leg muscles during gait have been used to clinically assess disease or injury. Several of the methods that have been reported for conditioning gait EMG signals were compared using data collected from clinically normal subjects walking on a treadmill. Specifically investigated were the effects of filtering and the quantity of data averaged upon several statistical tests that measure the variability of, or differences between, EMG profiles. Our results suggest that the variance ratio (VR) provides a reasonable test of data variability because of its modest sensitivity to both the degree of filtering and the amount of data averaged. They also suggest that of the comparison statistics: Pearson's r, the Kolmogorov-Smirnov T test and the ANOVA F ratio, the T test was the most reliable in detecting differences between given profiles for all test conditions. However, recognition of this ability of the T test must be tempered by the knowledge that while obvious EMG signal differences did exist, observable functional differences in gait did not. The relationship between statistically similar/dissimilar EMG patterns and clinically functional/dysfunctional gait patterns needs to be established. In addition, since all of the test statistics studied were affected to some degree by filtering and averaging, care should be used when comparing statistical results from separate studies unless it is known that the studies were conducted under similar conditions, including data processing. To that end, we recommend that at least 20 strides be used in the averaging process since the statistics we tested have reached or are asymptotically approaching their final values by this point.

Analysis of Variance↗
PubMed1994

Popliteus function in ACL-deficient patients.

Anterior cruciate ligament (ACL) injuries commonly result in anterolateral instability, resulting in a "pivot shift" phenomenon. Given that popliteus muscle stimulation results in a pivot shift, others have postulated that the popliteus muscle has a role in the pivot shift phenomenon. We hypothesized that patients with instability from ACL injuries may have excessive popliteus muscle activity. Therefore, we studied the EMG activity (using fine wire electrodes) of the popliteus muscle in sixteen normal subjects and ten ACL-deficient subjects. We recorded the EMG in six activities (level walking and jogging, ascending walking and jogging, and descending walking and jogging). Person's Product Moment Correlations were above 0.7, except in the case of ascending the treadmill (r = 0.427) and ascending jogging (r = 0.645), suggesting that the timing of the signals was similar for injured and uninjured limbs. Variance ratios for the injured and uninjured limbs were statistically similar, suggesting similar variability of patterns. Thus, we observed only minor popliteus EMG signal differences in this group of patients. We conclude that the popliteus muscle does not contribute to instability in the studied activities.

Anterior Cruciate Ligament Injuries↗
PubMed1991

Are leg electromyogram profiles symmetrical?

Electromyographic (EMG) patterns reflect function of the neuromuscular system. Abnormality of a given pattern may be established by comparison with that of the contralateral (presumably normal) limb if one ensures a difference beyond normal degrees of symmetry. We studied EMG patterns in six homologous knee muscles during freely selected, slow, and fast gaits in normal subjects. EMG signals were electronically conditioned to produce linear envelopes; envelopes from at least eight cycles from each subject at each speed were ensemble averaged. Grand ensemble averages for each muscle and speed were assembled from all subjects for right and left muscles. Transformed correlation coefficients (r') and variance ratios established the degree of similarity. All muscles exhibited a fair degree of symmetry (mean r' = 0.797-0.953), but we saw exceptions. On rare occasion, muscles repeatedly exhibited monophasic signals on one side and biphasic on the other. With increasing speed, signals generally became more repeatable, but we occasionally saw monophasic patterns becoming biphasic or vice versa. Considerable caution is essential before presuming any given pattern is abnormal. To ensure that a given pattern is abnormal one could establish that the pattern lies outside some statistical limits for normal population patterns controlled for speed and outside statistical limits for normal symmetry. Alternatively, one could determine the level of statistical differences in EMG patterns associated with distinct differences in level of functional performance between normal subjects and patients.

Adult↗
PubMed1991

Transcutaneous blood flow measurements in arteries of the human hand.

Technical advances in twenty MHz pulsed ultrasonic Doppler velocimetry (PUDVM) permit increasingly accurate measurements of blood flow in small vessels. This study applied advanced twenty MHz PUDVM methods to the transcutaneous, noninvasive quantitation of blood flow in arteries of the human hand. One hundred forty-four measurements were completed bilaterally in the digital arteries of all fingers and in the distal radial and ulnar arteries of the forearm. The data were averaged by artery for maximum velocity and average volumetric flow. The maximum velocity for digital and forearm arteries was about 20 centimeters per second and 50 centimeters per second, respectively. The average volumetric flow for these same arteries was about 0.02 cubic centimeters per second and 0.18 cubic centimeters per second, respectively. Statistical analysis demonstrated no differences between paired, contralateral arteries; within given fingers a difference occurred only between the radial and ulnar arteries of the index finger.

Adult↗
PubMed1988

Effects of episodic air hammer usage on digital artery hemodynamics of foundry workers with vibration white finger disease.

Blood flow was measured in the proper radial digital arteries of 20 subjects, 11 of whom were experienced pneumatic chipping hammer operators with varying degrees of vibration white finger (VWF). Flow was measured noninvasively and transcutaneously using a 20-MHz pulsed ultrasonic Doppler velocimeter (PUDVM), both in the resting state and after performing a supervised 20-minute chipping sequence. Approximately equivalent pre-chipping flow rates were present in six chippers with severe VWF, in the remaining five chippers without severe VWF, and in nine age-matched chipping novices. However, the digital artery flow rates of the severe VWF group increased substantially (to about three times the resting level) after the chipping episode, whereas the flow rates of the novices and the non-VWF chippers did not change appreciably. The VWF blood flow increases were accompanied by an 11% heart rate increase, by a 60% increase in lumen cross-sectional area at the PUDVM scan site, and by a very substantial reduction in downstream resistance (a 90% increase in temporospatial mean velocity).

Blood Flow Velocity↗
PubMed1986

Hemodynamics after autogenous, interpositional grafting in small arteries.

This investigation initiates the quantitative, hemodynamic assessment of interpositional grafts in small rat arteries. The left femoral arteries in 16 Sprague-Dawley rats were transected at two levels, and were then repaired using interrupted suturing technique. This effectively provided an ideally sized and histologically matched interposition graft. The 20-MHz PUDVM method was used to measure blood velocities, and derive values for vessel lumen area, temporal mean of the spatial mean velocity (Vsm), and volumetric flows. Measurements were completed distal to the interposed graft. Variables were quantitated in the preoperative and at the 5-, 15-, and 30-minute postoperative intervals. Statistical analysis of data indicated that the interpositional grafting procedure resulted in increased vessel lumen area and decreased Vsm, but, importantly, volumetric flow (about 8.20 ml/min) remained unchanged. This study demonstrated that, although hemodynamic characteristics are altered, volumetric flow can be restored after an experimental, interpositional grafting procedure in small arteries.

Animals↗
PubMed1986

Peripheral hemodynamic stability during prolonged anesthesia in the rat.

The present study tests the hypothesis that peripheral hemodynamics in the rat femoral artery remain relatively stable during 3 hours of general anesthesia. Hemodynamic variables (pulse period, maximal centerline velocity, lumen diameter, and mean volumetric flow) were measured by the 20 MHz-pulsed ultrasonic Doppler velocimeter method at 30-minute intervals. The hemodynamic variables were not statistically different during the duration of the study. The mean values were pulse period 160 +/- 2 msec, maximal centerline velocity 37.0 +/- 1.9 cm/sec, lumen diameter 0.94 +/- 0.03 mm, and mean volumetric flow 1.92 +/- 0.19 cc/min.

Anesthesia, General↗
PubMed1985

A hemodynamic evaluation of cuffed microarteriorrhaphy.

A cuffing technique and a standard interrupted suturing technique of microarteriorrhaphy were compared in the rat femoral artery. The comparison was based on hemodynamic variables, which were measured by 20-MHz pulsed ultrasound Doppler velocity meter (PUDVM) method. The hemodynamic variables included measured blood velocity and vessel lumen diameters, and calculated volumetric flows. Measurements were completed at 5-, 10-, and 20-minute intervals after vessel repair. Data from 26 experimental animals were suitable for analysis, with 15 animals in the standard repair group and 11 animals in the cuffed group. All variables were statistically similar prior to the surgical procedure, indicating that the study groups were appropriate for comparison. The measured lumen diameters were not statistically different at any time interval (P = .06). However, the velocities and the volumetric flow were statistically different (P less than .05) between groups at all time intervals. These values returned toward normal preoperative values over time. The cuffing technique used in this study was not as efficacious as the standard technique of microarteriorrhaphy, when evaluated by 20-MHz PUDVM-derived hemodynamic criteria.

Animals↗
PubMed1985

Some characteristics of laminar flow velocity spectra detected by a 20 MHz pulsed ultrasound Doppler.

For the purpose of improving accuracy of noninvasive flow measurements in small (1-2 mm diameter) blood vessels, an existing 20 MHz pulsed ultrasound Doppler velocimeter (PUDVM) has been augmented to allow fast Fourier transformation (FFT) of its Doppler shift signal. The modified instrument was used to collect velocity spectra for a benchtop test section delivering precise Poiseuille flows at velocities in the range of physiological interest. The velocity spectra demonstrated a substantial degree of broadening, much of which was attributable to the geometry of the finite sample volume size. Several spectral indices were studied as a function of flow field variables. Results showed that the intensity-weighted mean Doppler shift frequency, when converted to its corresponding velocity vM, agreed very closely with the theoretically predicted local fluid velocity. Measurement linearity and repeatability were evaluated for a number of system variables, indicating that FFT performance was essentially unaffected by several parameters capable of causing major degradation of (phasic) Doppler shift signals produced by conventional zero-crossing-counter circuitry. As presently configured, the augmented PUDVM instrument is fully capable of detailed flow field mapping in small subcutaneous vessels such as human digital arteries.

Blood Flow Velocity↗
PubMed1985

Social support and long-term lithium outcome.

The failure rate in long-term lithium treatment of bipolar affective disorder is in the range of 20 to 30%, even with rigorous diagnostic criteria an adequate serum lithium levels. This may be due to a variety of biologic and psychosocial factors. Psychosocial factors affecting treatment outcome were studied in 60 RDC diagnosed bipolar patients treated with lithium for one year. Outcome was measured using an affective episode score, a social adjustment scale and a global assessment scale. Social support was the factor most strongly correlated with a good outcome on all three measures.

Adult↗
PubMed1978

A light-emitting diode system for the analysis of gait. A method and selected clinical examples.

The purpose of this study was to design, develop, and test a comprehensive and potentially clinically useful system for the objective evaluation of sagittal-plane motion and temporal and distance factors during gait. A light-emitting diode and a 35 mm single-frame color slide photographic technique were utilized. The method of data collection and reduction produced values that are similar to reports in previous literature. High reliability was shown both within and across investigators testing normal subjects. Across-investigator comparisons when taking angular measurements demonstrated lower reliability. Specific clinical examples are presented to demonstrate the applicability of the light-emitting diode system.

Gait↗
PubMedDate not supplied

AIDS presenting as mania.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗