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PubMed1999

Effects of pacing when using material handling manipulators.

Common manipulator-assisted materials handling tasks were performed in a laboratory simulation at self-selected and faster (paced) speeds. The effects of pacing on peak hand forces, torso kinematics, spine moments and forces, and muscle antagonism were determined, along with any influences of several task variables on these effects. The faster trials were performed 20% more rapidly than the self-paced trials. It was found that (a) achieving this level of performance required approximately 10% higher hand forces and 5%-10% higher torso moments, (b) consistent torso postures and motions were used for both speed conditions, and (c) the faster trials resulted in approximately 10% higher spine forces and approximately 15% higher levels of lumbar muscle antagonism. On whole, these results suggest a higher risk of musculoskeletal injury associated with performance of object transfers at faster than self-selected speeds with and without a manipulator. Further analysis provided evidence that the use of manipulators involves higher levels of motor coordination than do manual tasks. Several implications regarding the use of material handling manipulators in paced operations are discussed. Results from this investigation can be used in the design, evaluation, and selection of material handling manipulators.

Biomechanical Phenomena↗
PubMed1999

Effect of lifting belts on trunk muscle activation during a suddenly applied load.

The National Institute for Occupational Safety and Health suggests there is insufficient biomechanical or epidemiological evidence to recommend the use of back belts in industry. From a biomechanical perspective, previous work suggests that lifting belts stiffen the torso, particularly in the frontal and transverse planes. To determine whether lifting belts stiffen the torso and alter the trunk muscle response during a sudden loading event, we tested the hypotheses that (a) lifting belts alter peak muscle activity recorded with electromyography (EMG) during sudden loading and (b) lifting belts have a larger impact on trunk muscle response when sudden loads are applied asymmetric to the torso's midsagittal plane. A sudden load was delivered to 10 men and 10 women without history of low back disorder via a cable attached to a thoracic harness; motion was restricted to the lumbar spine. Results indicate that gender was not a significant factor in this study. The lifting belt reduced the peak normalized EMG of the erector spinae muscles on average by 3% during asymmetric loading, though peak normalized EMG was increased by 2% during symmetric loading. Lifting belts have been shown to slightly reduce peak erector spinae activity during asymmetric sudden loading events in a constrained paradigm; however, the effects of lifting belts are too small to provide effective protection of workers. Actual or potential applications include the assessment of lifting belts as protective devices in workers based on the effects of lifting belts on the trunk muscle activity.

Adult↗
PubMed2002

Space radiation absorbed dose distribution in a human phantom.

The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose-rate predictions are 20% lower than the observations. Assuming that the trapped-belt models lead to a correct orbit-averaged energy spectrum, the measurements of dose rates inside the phantom cannot be fully understood. Passive measurements using 6Li- and 7Li-based detectors on the astronauts and inside the brain and thyroid of the phantom show the presence of a significant contribution due to thermal neutrons, an area requiring additional study.

Abdomen↗
PubMed1993

Effects of head cooling on cardiovascular and body temperature responses during submaximal exercise.

Cardiovascular and body temperature responses during submaximal exercise (25% and 50% VO2max) were investigated using female subjects (n = 6) in two separate experiments; one with head cooling and heating and the other with torso heating with and without head cooling. To supply the heat load, a liquid conditioned cap and vest were used. In the first experiment, a significant decrease in heart rate, oxygen intake (VO2) and cardiac output (Q) at relative work intensity of 50% VO2max was observed by head cooling. These results show that head cooling is very effective to reduce the physiological strain. In the second experiment, Q as a function of VO2 during torso heating was decreased by head cooling. However, the tympanic membrane temperature during head cooling at 15 degrees C was significantly higher than that at 20 degrees C and it was almost the same level with torso heating without head cooling. The results suggest that excess head cooling is not beneficial in terms of improving the body heat dissipation.

Body Temperature Regulation↗
PubMed2005

MRI of prostate cancer at 1.5 and 3.0 T: comparison of image quality in tumor detection and staging.

OBJECTIVE: This prospective study was performed to compare the image quality, tumor delineation, and depiction of staging criteria on MRI of prostate cancer at 1.5 and 3.0 T. SUBJECTS AND METHODS: Twenty-four patients with prostate cancer underwent MRI at 1.5 T using the combined endorectal-body phased-array coil and at 3.0 T using the torso phased-array coil, among them 22 before undergoing radical prostatectomy. The prostate was imaged with T2-weighted sequences in axial and coronal orientations at both field strengths and, in addition, with an axial T1-weighted sequence at 1.5 T. Preoperative analysis of all MR images taken together was compared with the histologic findings to determine the accuracy of MRI for the local staging of prostate cancer. In a retroanalysis, the image quality, tumor delineation, and conspicuity of staging criteria were determined separately for both field strengths and compared. Statistical analysis was performed using Wilcoxon's and the McNemar tests. RESULTS: In the preoperative analysis, MRI (at both 1.5 and 3.0 T) had an accuracy of 73% for the local staging of prostate cancer. The retroanalysis yielded significantly better results for 1.5-T MRI with the endorectal-body phased-array coil in terms of image quality (p < 0.001) and tumor delineation (p = 0.012) than for 3.0-T MRI with the torso phased-array coil. Analysis of the individual staging criteria for extracapsular disease did not reveal a superiority of either of the two field strengths in the depiction of any of the criteria. CONCLUSION: Intraindividual comparison shows that image quality and delineation of prostate cancer at 1.5 T with the use of an endorectal coil in a pelvic phased-array is superior to the higher field strength of 3.0 T with a torso phased-array coil alone. As long as no endorectal coil is available for 3-T imaging, imaging at 1.5 T using the combined endorectal-body phased-array coil will continue to be the gold standard for prostate imaging.

Aged↗
PubMed2000

Metabolic and cardiorespiratory responses to continuous box lifting and lowering in nonimpaired subjects.

STUDY DESIGN: A within-subject experimental design. OBJECTIVES: To compare the magnitude of metabolic and cardiorespiratory changes produced during box lifting and lowering among combinations of lift technique (leg lift and leg-torso lift) and lift weight (10.8 and 15.4 kg). BACKGROUND: Continuous box lifting and lowering can be used as an exercise in a low-back rehabilitation program. Awareness of the possible cardiovascular stress of this activity is important to the clinician because some patients may have existing cardiovascular pathologies or possess unknown risk factors for cardiovascular disease. METHODS AND MEASURES: A group of 17 nonimpaired men 26 +/- 8 years of age (mean +/- SD) performed the 4 experimental trials on different days in a counterbalanced order determined by a Latin Square design. Lifting and lowering was performed for 6 continuous minutes at a rate of 12 cycles per minute. Physiologic variables were oxygen uptake, minute ventilation, heart rate, systolic blood pressure, diastolic blood pressure, metabolic equivalent, and rate-pressure product. RESULTS: There were stepwise increases in the values for oxygen uptake, minute ventilation, heart rate, metabolic equivalent, and rate-pressure product from the leg-torso lift to the leg lift and from 10.8 to 15.4 kg of weight within each lift technique (with the exception that minute ventilation and heart rate did not differ between the leg-torso lift at 15.4 kg and the leg lift at 10.8 kg). For the 4 lifts, values (mean +/- SD) varied from 20.3 +/- 5.4 to 28.8 +/- 5.8 mL x kg x min(-1) for oxygen uptake, 42.2 +/- 11.1 to 66.4 +/- 15.2 L x min(-2) for minute ventilation,129 +/- 20.6 to 156 +/- 16.5 beats x min(-1) for heart rate, 5.8 +/- 1.6 to 8.2 +/- 1.6 for metabolic equivalent, and 197 +/- 49.4 to 245 +/- 41.2 for rate-pressure product (x10(-2)). CONCLUSION: The leg lift with the 15.4-kg weight produced the greatest physiologic stress. Because of the magnitude of the increase in the variables measured for all 4 types of lifts, clinicians should closely monitor patients' response to this type of exercise.

Adult↗
PubMed1997

Phenotypic characterization of rambouillet sheep expression the callipyge gene: III. Muscle weights and muscle weight distribution.

Paternal half-sibling Rambouillet ram lambs (n = 18) representing two muscle phenotypes were slaughtered at 54.5 kg to evaluate the effect of the callipyge gene on muscle mass. Lambs were produced from a sire that was heterozygous for the callipyge gene. Nineteen muscles were dissected from the right side of each carcass to evaluate muscle weights relative to carcass weight. Excised muscle mass as significantly higher (42%) for lambs exhibiting a callipyge muscle phenotype than for half-siblings. In the pelvic limb, all excised muscles except the peronius tertius were larger in lambs expressing the callipyge gene (P < .001). In the torso, the longissimus (P < .001), psoas major (P < .001), and psoas minor (P < .01) were larger in lambs with the callipyge phenotype. In the thoracic limb, the biceps brachii (P < .001) triceps brachii (P < .002), and extensor carpi radialis (P < .01) were larger in lambs with the callipyge phenotype. Total pelvic limb (P < .001) torso (P < .001), and thoracic muscle weights were higher (P < .01) in lambs with the callipyge phenotype. Callipyge lambs had a higher (P < .01) percentage of excised muscle weight in the pelvic limb and torso and a lower (P < .01) percentage in the thoracic limb when compared to controls. These data indicate that the magnitude of expression of the callipyge gene is dependent upon the location of the muscle on the body and that the increased muscle mass was concentrated in the leg and loin.

Animals↗
PubMed1989

Perceived self-motion elicited by postrotary head tilts in a varying gravitoinertial force background.

We measured the effects of postrotary head tilts on the perceived duration and the apparent axis of illusory self-rotation experienced following counterclockwise body rotation in high (1.8 G), normal (1 G), and low (0 G) gravitoinertial force environments. In the absence of head movements, the duration of illusory afterrotation was shorter in 0 G and 1.8 G than in 1 G, and it was further shortened by 40 degrees pitch-back head movements in 1 G and 1.8 G. Clockwise illusory afterrotation about the torso's vertical z-axis was always experienced in trials without postrotary head tilts. In trials with head movements, half the subjects experienced no change in this pattern; however, half experienced transient rightward roll of the torso's z-axis, which remained the rotation axis. The duration and extent of apparent roll were greater in 0 G and smaller in 1.8 G than in 1 G. We provide a functional explanation for the tendency for perceived self-rotation to be determined relative to the torso and to the gravitoinertial vertical rather than solely in relation to head position and head-fixed angular velocity sensors.

Adult↗
PubMed2002

Body surface mapping after partial left ventriculotomy.

OBJECTIVE: To demonstrate cardiac electrophysiological changes in patients where partial left ventriculotomy was performed and multichannel electrocardiographical measurements and body surface potential mapping were used. METHODS: Body surface ECG signals were recorded during sinus rhythm for one minute. Six patients were operated on with partial left ventriculotomy were monitored. All patients had normal coronary angiography data. The data were acquired prior to the partial left ventriculotomy, and on the second, third, fourth, and fifth postoperative day using 32-body surface leads. The recorded data were analysed by determining ST-40 and QRS integral maps. The analysis was done on a set of selected beats during the sinus rhythm and on the averaged beats. RESULTS: Before the operation, ST-40 maps typically showed an area of strong positive potentials (elevation) over the anterior aspect of the torso and a region of strong negative potentials (depression) over the lateral, and posterior aspects of the torso. After the operation, the ST elevation over the anterior, lateral and posterior aspects of the torso was reduced. An area of marked positive potentials remained in the precordial area (overlying the excised area of the heart), even during the postoperative monitoring interval (day two through day five). We also noticed that the amplitude of cardiac signals decreased by approximately 30% after the partial left ventriculotomy. Qualitative map changes were substantiated by statistical parameters. CONCLUSIONS: Results of our study demonstrate that noninvasive acquisition of body-surface electrocardiographs may detect changes in the cardiac activity of patients undergoing partial left ventriculotomy. This finding suggests that body surface mapping may also be useful in assessing the arrhythmia vulnerability.

Adult↗
PubMed2002

Measuring the axial rotation of lumbar vertebrae in vivo with MR imaging.

BACKGROUND AND PURPOSE: Flexion-extension radiography is neither sensitive nor specific in the diagnosis of degenerative spinal instability, a presumed cause of back pain and an indication for spinal fusion. We tested the hypothesis that with MR imaging and a device to rotate the torso, axial rotations of lumbar vertebrae can be measured with sufficient accuracy and that significantly different rotations can be detected between lumbar segments with degenerated disks and those with normal disks. METHODS: We studied five volunteers without back pain (group 1), five patients who underwent MR imaging because of back pain but were not considered candidates for fusion (group 2), and five patients in whom diskography identified one or more disks with concordant pain (group 3). Each participant was placed on a specially built table that provided separate supports for the torso and for the hips and legs. Series of sagittal images were acquired with a T2-weighted fast spin-echo sequence, with the torso rotated clockwise and then counterclockwise. The amount of rotation was calculated from axial images with use of an automated program. RESULTS: In the five volunteers, rotations of the lumbar motion segments varied between -1.8 degrees and 5.7 degrees, with an average of 0.8 degrees. The abnormal disks in five patients in group 2 rotated from -0.9 degrees to 5.6 degrees, with an average of 3.2 degrees. In group 3, the disks in which concordant pain was elicited rotated from 0.8 degrees to 4.4 degrees, with an average of 2.2 degrees. Difference in rotation between abnormal and normal disks was statistically significant. CONCLUSION: Measurements of rotations of lumbar vertebrae with MR imaging may have value for determining levels that move abnormally in axial rotation.

Adult↗
PubMed1999

NTP Studies of Magnetic Field Promotion (DMBA Initiation) in Female Sprague-Dawley Rats (Whole-body Exposure/Gavage Studies).

Electric and magnetic fields are associated with the production, transmission, and use of electricity; thus, the potential for human exposure is high. These elec-tric and magnetic fields are predominantly of low fre-quency (60 Hz in the United States and 50 Hz in Europe) and generally of low intensity. Because some epidemiology studies and initiation/promotion studies in rats have suggested a potential for increased breast cancer rates with increasing magnetic field exposure, the ability of 50- and 60-Hz magnetic fields to pro-mote mammary gland tumors initiated by the administration of 7,12-dimethylbenz(a)anthracene (DMBA) was examined in female Sprague-Dawley rats in 13- and 26-week whole-body exposure studies. Additional animals were evaluated for changes in pineal gland and serum melatonin concentrations. FIRST 13-WEEK STUDY: Groups of 100 female Sprague-Dawley rats were ad-ministered 20 mg DMBA (four weekly gavage doses of 5 mg in sesame oil) and exposed to 1 G 50-Hz, 5 G 50-Hz, or 1 G 60-Hz magnetic fields for 18.5 hours per day, 7 days per week, for 13 weeks. A group of 100 rats administered 20 mg DMBA served as DMBA controls. A group of 100 vehicle control rats was administered only sesame oil on the same schedule. Additional groups of 10 rats receiving similar treatment were evaluated for pineal gland and serum melatonin concentrations at 4, 8, or 12 weeks. All vehicle control rats survived to the end of the study. Of the animals administered 20 mg DMBA, 6 rats in the DMBA control group, 13 in the DMBA/1 G 50-Hz group, eight in the DMBA/5 G 50-Hz group, and five in the DMBA/1 G 60-Hz group died or were removed from the study prior to the final necropsy. Final mean body weights and body weight gains of the DMBA/1 G 50-Hz and DMBA/1 G 60-Hz groups and the mean body weight gain of the DMBA/5 G 50-Hz group were slightly greater than those of the DMBA control group. Clinical findings including torso masses and ulcers (on the mammary masses) were attributed to DMBA administration. The numbers of palpable mammary gland tumors, tumor sizes, and total tumor areas in DMBA/magnetic field groups were similar to those in the DMBA control group. Relative to the DMBA control group, exposure to magnetic fields did not significantly affect overall incidences of mammary gland neoplasms or nonneoplastic lesions in the DMBA/magnetic field groups. SECOND 13-WEEK STUDY: Groups of 100 female Sprague-Dawley rats were ad-ministered 8 mg DMBA (four weekly gavage doses of 2 mg in sesame oil) and exposed to 1 G 50-Hz or 5 G 50-Hz magnetic fields for 18.5 hours per day, 7 days per week, for 13 weeks. A group of 100 female rats administered 8 mg DMBA served as DMBA controls. Additional groups of 10 rats receiving similar treatment were evaluated for pineal gland and serum melatonin concentrations at 4, 8, or 12 weeks. Except for one rat in the DMBA/5 G 50-Hz group, all rats survived until the end of the study. Final mean body weights of DMBA/magnetic field groups were similar to those of the DMBA control group. Clinical findings including torso masses and ulcers were attributed to DMBA administration. The numbers of palpable mammary gland tumors, tumor sizes, and total tumor areas in DMBA/magnetic field groups were similar to those in the DMBA control group. Relative to the DMBA control group, exposure to magnetic fields did not significantly affect overall incidences of mammary gland neoplasms or nonneoplastic lesions in the DMBA/magnetic field groups. 26-WEEK STUDY: Groups of 100 female Sprague-Dawley rats were administered 10 mg DMBA (in sesame oil) by gavage followed by exposure to 1 G 50-Hz, 5 G 50-Hz, or 1 G 60-Hz magnetic fields for 18.5 hours per day, 7 days per week, for 26 weeks. A group of 100 female rats administered 10 mg DMBA served as DMBA controls. Another 100 vehicle control rats were administered only sesame oil. Additional groups of 10 rats receiving similar treatment were evaluated for pineal gland and serum melatonin concentrations at 4, 8, or 12 weeks. All rats in the vehicle control group survived until the end of the study. Twelve rats in the DMBA control group, 15 in the DMBA/1 G 50-Hz group, 9 in the DMBA/5 G 50-Hz group, and six in the DMBA/1 G 60-Hz group died or were removed during the study. The final mean body weights and body weight gains of the DMBA/1 G 50-Hz and DMBA/5 G 50-Hz groups were significantly greater than those of the DMBA control group. Clinical findings including torso masses, abscesses, and ulcers were attributed to DMBA administration. The pineal gland melatonin concentrations of DMBA/5 G 50-Hz and DMBA/1 G 60-Hz rats were significantly greater than that of the DMBA controls at week 12; however, these data were highly variable between individual animals within each group. The numbers of palpable mammary gland tumors, tumor sizes, and total tumor areas in DMBA/magnetic field groups were similar to those in the DMBA controls. The incidences of mammary gland carci-noma (including multiple) in the DMBA/1 G 60-Hz group were significantly decreased relative to the DMBA control group. CONCLUSIONS: In an initiation/promotion study in which female Sprague-Dawley rats were initiated by four weekly doses of 5 mg DMBA per rat beginning at 50 days of age and exposed to 50-Hz magnetic fields at 1 or 5 G field intensities or to 1 G 60-Hz magnetic fields for 13 weeks, there was no evidence that magnetic fields promoted the development of mammary gland neoplasms. The prevalence and multiplicity of mammary gland carcinomas in all DMBA groups limited the ability of this assay to detect a promoting effect of magnetic fields. In an initiation/promotion study in which female Sprague-Dawley rats were initiated by four weekly doses of 2 mg DMBA per rat beginning at 50 days of age and exposed to 50-Hz magnetic fields at 1 or 5 G field intensities for 13 weeks, there was no evidence that magnetic fields promoted the development of mammary gland neoplasms. In an initiation/promotion study in which female Sprague-Dawley rats were initiated by a single 10 mg DMBA dose at 50 days of age and then exposed to 50-Hz magnetic fields at 1 or 5 G field intensities or to 1 G 60-Hz magnetic fields for 26 weeks, there was no evidence that magnetic fields promoted the development of mammary gland neoplasms.

Journal Article↗
PubMed2003

Malignant melanoma and (18)F-FDG-PET: Should the whole body scan include the legs?

AIM: (18)F-FDG-PET (FDG-PET) is established in staging and follow-up of malignant melanoma. The legs are affected in 10-40% at time of diagnosis even if the primary is at the arms and torso. Imaging including the legs may detect distant manifestations but increases duration of the scan by approximately 30 min. We intended to disclose the diagnostic benefit of scanning the legs and to evaluate the therapeutic benefit resulting. PATIENTS, METHODS: In this retrospective analyse 213 consecutive PET studies of 153 patients with suspected or recent malignant melanoma were re-evaluated for metastatic spread by a blinded investigator. Histopathological follow-up was assessed for confirmation. RESULTS: Suspicious findings at the legs were depicted in 53 patients on 76 occasions. 38/53 showed pathologic uptake in the torso as well. In 15/53 patients it was restricted to the legs. One of them had a hitherto unknown, clinically relevant finding that was not apparent in palpation and inspection. In 6 other patients with primary location at the legs a validation of the positive PET findings was not possible up to now. CONCLUSION: Metastases and local recurrence of malignant melanoma at the legs were found in 41% of women and 27% of men. However, a long scan does not yield relevant additional data. We found isolated new manifestations at the legs in only 1/153 patients. We recommend performing a long scan only in patients with previous melanoma manifestations restricted to the legs. In all other cases a short scan of the torso and proximal thighs is sufficient. This allows a higher number of PET-scans without loss of diagnostic power and a shorter examination time.

Fluorodeoxyglucose F18↗
PubMed1992

Effects of surgical decapitation and chicken growth hormone (cGH) replacement therapy on chick embryo growth.

The effects of decapitation and chicken growth hormone (cGH) replacement therapy on chick embryo growth has been investigated. Removal of the prosencephalon at 33-38 hrs (1.38 to 1.58 Days) of incubation decreased body (torso) and liver weights as well as skeletal growth as indicated by tibial length. A single pituitary gland transplanted onto the chorioallantoic membrane (CAM) partially restored torso growth and completely reversed the increase in body water content which characterizes decapitated embryos. Replacement therapy with cGH did not influence body weight but did, on Day 16.5 of incubation, increase tibial length and liver DNA content and concentration. These latter findings suggest that there may be limited hypothalamoadenohypophyseal (GH) axis function in the chick embryo. The effects of decapitation on torso growth are also discussed in conjunction with decapitation effects on albumen swallowing (absorption) and yolk absorption.

Albumins↗
PubMed2002

Personalized biomechanical modeling of Boston brace treatment in idiopathic scoliosis.

The aim of this study was to describe how the Boston brace modify the scoliotic curvatures using a finite element (FE) model and experimental measurements. The experimental protocol, applied on 12 scoliotic girls, was composed of the pressure measurement at the brace-torso interface followed by two radiographic acquisitions of the patient's torso with and without brace. A 3D FE model of the trunk was built for each unbraced patient. The brace treatment was represented by two different modeling approaches: 1) using equivalent forces calculated from the measured pressures; 2) by an explicit personalized FE model of the brace (hexahedral elements) and its interface with the torso (contact elements). In the first model, measured brace forces less than 40N and up to 113N induced respectively less than 21% and up to 87% of real correction. Thoracic forces induced the main correction, affecting partially both lumbar and thoracic curves, in agreement with the literature. In the second model, the brace closing reduced the curves up to 35% of real correction. Contact reaction forces (16-79N) were similar to real brace forces (11-72N). The results suggested that other mechanisms than brace pads contribute to the equilibrium of the patients. Postural control by the muscular system remains a problem to address in a future study. The second model represented more realistically the load transfer from the brace to the spine than external forces application. With such model, it is expected to predict the effect of a brace before its design and manufacturing, and also to improve its design.

Adolescent↗
PubMed2005

Desensitization to strong vestibular stimuli improves tolerance to simulated aircraft motion.

INTRODUCTION: The extent to which tolerance acquired in one motion environment can be transferred to another has not been fully elucidated. This study compares three provocative motion stimuli and whether tolerance acquired from cross-coupled motion and torso rotation can be transferred to simulated aircraft motion. METHOD: There were 18 healthy subjects (9 men and 9 women), 18-44 yr of age, who were divided into 3 groups. Each group was exposed to the following desensitization procedure in a pseudo-random repeated measures design. In condition D1, subjects were exposed to 4 consecutive days of cross-coupling and on the 5th d they were exposed to simulated aircraft motion. In D2, subjects were exposed to 4 consecutive days of torso rotation and on the 5th day they were exposed to the simulated aircraft motion as in D1. In D3, subjects were exposed to 5 consecutive days of simulated aircraft motion. Based on Graybiel's diagnostic criteria, severity of motion sickness on the 1st and 5th day in D1, D2, and D3 were compared. RESULTS: Cross-coupled motion was the most provocative stimulus followed by torso rotation and simulated aircraft motion. Within each motion stimulus, there was evidence of desensitization (p < 0.001) within 4 d. There were no significant differences in the severity of motion sickness observed on the 5th day regardless of the desensitization stimuli. CONCLUSION: Our results suggest that desensitization to one provocative motion could be transferred to a less severe motion stimulus. This result could be used in the refinement of desensitization programs for aircrew.

Adaptation, Physiological↗
PubMed2005

Full-body gaze control mechanisms elicited during locomotion: effects of VOR adaptation.

We have previously shown that multiple, interdependent, full- body sensorimotor subsystems aid gaze stabilization during locomotion. In the present study we investigated how the full-body gaze control system responds following exposure to visual-vestibular conflict known to adaptively modify vestibulo-ocular reflex (VOR) function. Subjects (n = 14) walked (6.4 km/h) on a motorized treadmill before and after they were exposed to 0.5X minifying lenses worn for 30 minutes during self-generated sinusoidal vertical head rotations performed while seated. Results indicate that, following the exposure the major changes that subjects showed were to: 1) decrease the amplitude of head pitch and vertical translation of the torso movement with respect to space; 2) increase the amount of knee and ankle flexion during the initial stance phase of the gait cycle. A correlation analysis showed that: 1) changes in the head pitch significantly co-varied with that of the vertical torso translation 2) changes in the knee flexion significantly co-varied with that of the ankle flexion during the initial stance phase of the gait cycle 3) changes in the vertical torso translation significantly co-varied with that of the ankle flexion during the initial stance phase of the gait cycle. Thus we infer that the changes in the magnitude after VOR adaptation in comparison to their pre adaptation responses serve to aid gaze stabilization during locomotion. The significant covariation of the changes between subsystems provides further evidence that the full body contributes to gaze stabilization during locomotion, and its different functional elements are subject to adaptive reorganization following exposure to visual-vestibular conflict.

Adaptation, Physiological↗
PubMed1989

Management of neuromuscular spinal deformities with Luque segmental instrumentation.

Forty-six patients who had a neuromuscular spinal deformity were treated with arthrodesis and Luque segmental spinal instrumentation and were followed for an average of three years. Twenty-two patients had cerebral palsy and twenty-four had another neuromuscular disease. In thirty-nine patients, the arthrodesis was extended to the sacrum. Eleven patients who had severe scoliosis as well as pelvic obliquity and decompensation of the torso had a combined anterior and posterior arthrodesis; the other thirty-five patients had a one-stage posterior procedure. Preoperatively, the average scoliosis was 74 degrees; this was corrected to 39 degrees at follow-up. Final corrections were similar for scoliosis and were better for pelvic obliquity and decompensation of the torso in patients who had combined anterior and posterior arthrodesis. The results for scoliosis and pelvic obliquity in patients who had a spastic deformity were similar to the results in patients who had a flaccid deformity. Correction of decompensation of the torso was better in patients who had a spastic deformity. Postoperatively, a brace was used in half of the patients in each group; this did not appear to affect the amount of correction in either group, although the result may have been influenced by the selection process. The rate of complications was 48 per cent. Pseudarthrosis occurred in three patients (6.5 per cent). There were no major neurological deficits related to the correction or to the use of sublaminar wires. Three patients died, one in the immediate postoperative period and the other two at eighteen months and four years after the original procedure, due to causes unrelated to the operation.

Adolescent↗
PubMed1989

Head cooling is desirable but not essential for preventing heat strain in pilots.

Liquid-cooled garments (LCGs) are being considered for reducing heat strain in pilots. While head cooling has been shown to be thermally efficient and subjectively desirable, it is technically difficult to achieve. This laboratory study was carried out to see if head cooling in addition to torso cooling is a necessity. Six male subjects wore a cooling vest and cap under summer flight clothing on three occasions in a climatic chamber set at Tdb = 42 degrees C, Twb = 32 degrees C (RH = 50%), Tg = 52 degrees C at head position, WBGT = 35 degrees C. Cooling conditions were: control (CTRL), no fluid circulation; condition VEST, only torso cooling; condition HEAD, both torso and head cooling. Cooling fluid was circulated from a reservoir maintained at 10 degrees C. Subjective thermal comfort assessments confirmed the desirability of head cooling, but performance measurements and physiological measurements of thermal strain showed no statistically significant differences between conditions VEST and HEAD. It was concluded that head cooling is desirable but not essential.

Adult↗