Nursing staff and airway management.
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Apnea↗
Biomedical subjects
T M Cook
Publications and source records attributed to T M Cook.
Percutaneous dilational tracheostomy.
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Humans↗
An electromyographic analysis of hip abductor muscle activity when subjects are carrying loads in one or both hands.
Forces produced at the hip joint as a result of hip abductor muscle contractions while carrying loads reach several times body weight (BW). Physical therapists often advise patients with hip osteoarthritis in ways to minimize these forces as a means of reducing the pain associated with carrying loads. The purpose of this study was to use surface electromyography (EMG) to quantify the relative demands placed on the hip abductors while carrying loads in one hand or in both hands. Thirty asymptomatic college-aged subjects walked while carrying loads of 10% and 20% of BW unilaterally and loads of 10%, 20%, and 40% of BW bilaterally. Signals from foot switches allowed a computer to average the EMG data over the phase of gait when the foot was in complete contact with the ground. All EMG data were normalized to a percentage of the EMG voltage produced during no-load walking (%EMG). Our prime dependent variable was the %EMG averaged over both hip sides of all subjects' multiple walking trials. Our major analysis involved a multifactorial analysis of variance for repeated measures with method of carry (unilateral or bilateral) and load as the two main independent variables. Results demonstrated that both the amount of the load and the method of load carry made a significant difference in regard to the amount of hip abductor EMG produced. Of particular note was the fact that the bilateral 20% of BW condition produced statistically less %EMG (when averaged over both sides) than did the unilateral 20% of BW condition. Persons with hip disease should be aware that hip joint forces may be reduced by the bilateral method of carrying loads.
Adult↗
Lumbar support thickness: effect on seated buttock pressure in individuals with and without spinal cord injury.
We compared the effects of different lumbar support thicknesses on seated buttock pressure in individuals with and without spinal cord injury (SCI). Eighteen subjects with SCI (SCI group) and 18 subjects without SCI (control group) were seated on a pressure-sensing transducer incorporated into an adjustable chair. The output was calibrated so that eight pressure intervals (colors) were displayed. The lumbar support thickness was adjusted to 0, 2.5, 5, and 7.5 cm, and the highest and lowest seated buttock pressures were analyzed. External measurements of the hip angle were taken for each lumbar support condition. High reliability of repeated seated test positions was found (intraclass correlation coefficient = .93). The 5- and 7.5-cm-thick lumbar supports caused a decrease in the highest pressure areas in the control group, but no change in the SCI group. The hip angle was increased with each increment in lumbar support thickness in both groups, but the SCI group's hip angle was consistently less than that of the control group for each lumbar support condition. The results of this study suggest that in individuals with chronic paralysis (greater than or equal to 3 years), the use of a wheelchair lumbar support has a negligible effect on seated buttock pressure.
Adult↗
Electromyographic activity of selected leg musculature in subjects with normal and chronically sprained ankles performing on a BAPS board.
The purpose of this study was to evaluate the magnitude and temporal features of tibialis anterior, peroneus longus, and gastrocnemius muscle activity during exercises performed on a Biomechanical Ankle Platform System (BAPS) board by subjects with normal and chronically sprained ankles. Fourteen participants in each of the two groups rotated the platform in both clockwise and counterclockwise directions at self-selected velocities. Trials were completed with both medium- and large-sized hemispheres under the platform while electromyographic surface recordings were made from the three muscles of interest. Electromyographic values, normalized within individuals as a percentage of maximal voluntary isometric contraction (MVIC), ranged from 20% to 80% of MVIC. An analysis of variance for the average myoelectric signals from all three muscles revealed no differences between the two groups. Effects of direction and hemisphere size were shown for all muscles. The large hemisphere produced significantly greater average activity and a more pronounced effect on the tibialis anterior muscle. The data provide information on the level of muscle activity required for conditions used in this study and may assist the physical therapist with making judgments about the use of this device in rehabilitation programs.
Adult↗
Characterization of a gyrB mutation responsible for low-level nalidixic acid resistance in Neisseria gonorrhoeae.
Nalidixic acid-resistant derivatives of Neisseria gonorrhoeae WR302 were identified and categorized into two classes on the basis of their susceptibilities to this antimicrobial agent. The MIC of nalidixic acid for the derivative strain MUG116 was fourfold greater than that for its isogenic parental strain WR302 (2 versus 0.5 micrograms/ml, respectively). MUG324 was significantly more resistant to nalidixic acid (greater than 64 micrograms/ml). The MICs of other antimicrobial agents known to interact with either the gyrA or gyrB gene products were determined. Although the nalidixic acid MIC for MUG116 increased, no significant increases in the MICs of other agents that interact with the gyrA gene product were seen. The MICs of all agents that interact with the gyrA gene product were significantly increased for MUG324. The gene that imparts low-level nalidixic acid resistance was cloned from strain MUG116. The DNA sequence of this gene was determined, and by comparing the deduced amino acid sequence with sequences of proteins in data bases, this protein was found to be approximately 70% homologous with the gyrB gene product of Escherichia coli.
Amino Acid Sequence↗
An electromyographic analysis of the hip abductor muscles during a standing work task.
Research data strongly suggest that osteoarthritis of the hip occurs statistically more often on the right side. A possible contributing factor to this right-sided bias in frequency may be that the articular cartilage on the right hip is subjected to relatively higher muscular-based forces throughout a lifetime. As an initial attempt to study this possibility, this research examined healthy persons to determine the existence of a "dominant" hip similar to that expressed for handedness. Electromyographic (EMG) analysis was used to compare the electrical activity between the right and left hip abductor muscles during a standardized standing work task using 40 right-handed and 40 left-handed healthy subjects. Analysis of the data showed that the hip muscle on the side of the subject's handedness produced higher normalized EMG activity than did the opposite hip; however, the differences were not all statistically significant. The trend of this data set, however, warrants further research into a possible association between hip dominance, asymmetrical muscle use, and the development of hip osteoarthritis.
Adult↗
Electromyographic analysis of hip abductor musculature in healthy right-handed persons.
The right hip abductor (HA) musculature has been reported to demonstrate stretch weakness attributable to chronic elongation imposed by standing posture common to right-handed healthy individuals. Research has shown side-specific differences in maximal isometric torque-hip abduction angle curves for the HA muscles in a similar population. The purposes of this study were to assess isometric hip abduction torque in a sample of 40 healthy right-handed persons and to compare side differences in the HA muscles' neural drive index across a wide range of hip abduction angles. The neural drive index was defined as the magnitude of the normalized surface electromyographic activity divided by the absolute magnitude of a submaximal (20% of maximal) isometric HA muscle torque. Data were collected while subjects were positioned supine with trunk and pelvis stabilized. Statistical analysis of the data did not support earlier research on right HA muscle stretch-weakness; however, trends in the data suggest the need for further research. We also discuss the functional role of the passive noncontractile elements of the HA musculature.
Adult↗
Lesion-induced CA1 mossy fibers in the rat represent a neoinnervation.
The developmental pattern of hippocampal mossy fiber (dentate granule cell axon) innervation to the pyramidal cell layer was examined with anterograde transport methods. Injection of 3H-leucine into the dentate gyrus on PN 1 resulted in labeling of the incipient stratum lucidum extending to, but not beyond, the CA3 region on PN 3 and 5. Since destruction of CA3 pyramidal cells on PN 5 results in aberrant mossy fiber innervation to CA1 pyramidal cells (Cook and Crutcher 1985), these results suggest that the presence of mossy fibers in CA1 of the rat represents a neoinnervation (perhaps representing a more primitive pattern of connectivity) and not the persistence of a transient developmental projection.
Animals↗
Effect of seat angle and lumbar support on seated buttock pressure.
The purpose of this study was to compare the effects of a lumbar support at two seat angles (0 degrees and 10 degrees of posterior tilt) on the area of highest buttock pressure. Twenty able-bodied subjects were seated on a pressure-sensing transducer incorporated into an adjustable chair (ischiobarograph). A video camera on the underside of the transducer detected changes in light levels in direct relation to pressure application. The camera output was processed by a microcomputer system that converted the signal into nine colors, each representing a distinct pressure interval in the range of 0 to more than 500 mm Hg. The microcomputer determined the area of each pressure interval before and after a 10-degree posterior tilt of the seat and lumbar support placement. The results demonstrated high test-retest reliability for each position (r = .95). A significant decrease in the six highest pressure intervals occurred when the lumbar support was used in both the upright and reclined positions (p less than .05). The results of this study have implications for wheelchair-dependent individuals.
Buttocks↗
Comparison of maximal isometric hip abductor muscle torques between hip sides.
A posturally induced "stretch weakness" of the right hip abductor muscles has been reported in many healthy right-handed persons in the literature. The purpose of this study was to test for differences in the maximal isometric hip abduction torque produced between hip sides across multiple hip abduction angles. The torques were measured on 40 healthy right-handed individuals using a specialized torque-testing table at hip abduction angles of -10, 0, 10, 20, 30, and 40 degrees. Statistical analysis of the results did not demonstrate a specific "weakness" of the right hip abductor muscles at the hip angle used to clinically test them. The results, however, did demonstrate statistically significant differences in the torque-hip angle slopes across hip sides. We hypothesized that these slope differences may result from muscle adaptation to lengths imposed by standing posture. We discuss how manual muscle testing procedures may bias the likelihood of encountering stretch weakness in muscles that are habitually maintained at near-maximal elongation.
Adult↗
The effects of load placement on the EMG activity of the low back muscles during load carrying by men and women.
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Adult↗
Intrahippocampal injection of kainic acid produces significant pyramidal cell loss in neonatal rats.
Previous reports have indicated that pyramidal cells in the developing rat hippocampal formation are not destroyed by intraventricular or intraperitoneal administration of kainic acid. We examined the neurotoxic properties of kainic acid and ibotenic acid following intrahippocampal injection in neonatal rats and found significant pyramidal cell death following injection of 1.0 microgram kainic acid in 6, 7 and 9-day-old pups. At doses 2.5 or five times this amount, significant pyramidal cell loss was obtained in 5-day-old rats as well. The susceptibility of pyramidal neurons to kainic acid increased as a function of age. The developing hippocampus was considerably more vulnerable to ibotenic acid compared with kainic acid, in contrast to the order of potency reported in adult rats. The increased sensitivity of CA3 pyramidal cells parallels the development of the mossy fiber innervation to the dendrites of these cells supporting the twofold mechanism suggested by Coyle for kainic acid neurotoxicity; that is, a direct cytotoxic action via postsynaptic receptors as well as increased sensitivity due to the presence of excitatory inputs.
Animals↗
Extensive target cell loss during development results in mossy fibers in the regio superior (CA1) of the rat hippocampal formation.
The axons of dentate granule cells (mossy fibers) have been reported to appear in the regio superior (CA1) of the rat hippocampal formation following destruction of the pyramidal cells in the regio inferior (CA3). We undertook the present experiments to confirm this finding and to determine the requirements for this dramatic neuronal rearrangement. We found that extensive (greater than 80%) loss of CA3 cells, as well as the presence of surviving CA1 neurons within a narrow period of development (postnatal days 3-5) is necessary, however apparently not sufficient, for the appearance of CA1 mossy fibers. That the absence of normal target cells during a restricted period of mossy fiber development will lead to their association with novel targets suggests that much of the specificity of this developing connection depends on the presence of normal targets during a critical period.
Animals↗
Effect of load and carrying position on the electromyographic activity of the gluteus medius muscle during walking.
Physical therapists often teach people with hip osteoarthritis ways to decrease gluteus medius muscle activity of the stance limb during gait. The rationale for decreasing this muscle activity is that hip muscle contraction needed for frontal plane hip stabilization is responsible for a large component of the hip joint compressive forces during stance. The magnitude and carrying position of external loads during walking are both variables that influence requirements of gluteus medius muscle force. Therefore, the purpose of this study was to determine through EMG, the relative amounts of gluteus medius muscle electrical activity produced during the stance phase of gait when subjects used varying combinations of load size (10 and 20% of body weight) and carrying position of the hands (contralateral or ipsilateral to a given hip, or anterior or posterior to the chest). We studied 24 healthy subjects and used their EMG activity during the stance phase of gait as an indication of the relative amount of myogenic hip compression force. Results indicated statistical differences in EMG according to carrying condition with the contralateral position (with loads of 10 and 20% of body weight) producing the highest levels of EMG. We discuss the kinesiologic reasons for results and the prevention of hip osteoarthritis in occupational settings.
Adult↗
Electromyography in biomechanics.
The purpose of this paper is to discuss the use of EMG as related to biomechanical function and dysfunction. The uses and limitations of this technique are described and instrumentation features and methods of data collection and interpretation are presented. We also discuss factors that influence the relationship of EMG to biomechanical measurements and cite as examples studies that have used EMG. Emphasis is placed on improving the ability of the physical therapist to use and interpret EMG data in kinesiology and biomechanics.
Biomechanical Phenomena↗
An electromyographic analysis of quadriceps femoris muscle setting and straight leg raising.
Physical therapists routinely advise patients to perform quadriceps femoris muscle setting or straight leg raising or both following knee surgery or trauma from knee injury. Little information exists, however, about the intensity of effort required from knee and hip musculature during the exercises. This study was designed to compare the level of electromyographic activity during maximally resisted straight leg raises with the level during quadriceps femoris muscle setting exercises for the vastus medialis, rectus femoris, gluteus medius, and biceps femoris muscles. Forty healthy young adult men and women performed randomly ordered trials of each exercise in the supine position. Electromyographic activity was recorded from surface electrodes and normalized to values derived from maximal isometric trials. Statistical analysis demonstrated significantly greater (p less than .0001) vastus medialis, biceps femoris, and gluteus medius muscle activity during quadriceps femoris muscle setting. The rectus femoris muscle was significantly more active (p less than .0001) during the straight leg raise. The study demonstrated remarkably different muscle activation levels between the exercises studied and clearly indicates that selection of the exercises needs to be based on the therapeutic objectives.
Adult↗
Surgical reconstruction for calcaneonavicular coalition. Evaluation of function and gait.
The function of nineteen patients was evaluated at three to fourteen years after reconstructive surgery for calcaneonavicular coalition. Measurements of subtalar motion, single-limb functional tests, and gait analyses were carried out to determine how function in these patients differed from normal. Better function correlated well with better postoperative subtalar motion. Patients with a unilateral coalition who had good subtalar motion after resection showed symmetrical gait patterns during tests of function of the subtalar joint under conditions of stress.
Adolescent↗