Growth pattern and behavioral traits associated with the development of the obese-hyperglycemic syndrome in mice (ob-ob).
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Aging↗
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Results for “REFLEX, POSTURAL”
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The sexual clasp as a reticularly controlled behavior in the toad, Bufo arenarum Hensel.
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Animals↗
Spinal compensation of postural cerebral asymmetries.
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Animals↗
Ethanol in cardiomyopathic hamsters: Na and water excretion and righting response.
This study examined the effects of ethanol and hereditary cardiomyopathy on sodium and water excretion by golden Syrian hamsters of both sexes. Ethanol (4 g/kg) or the isotonic saline vehicle were injected IP into 60-70-day-old hamsters of normal and cardiomyopathic (BIO 14.6) strains. Urine and blood were collected after 90 or 350 min in different groups. Cardiomyopathic hamsters more quickly lost their righting responses, eliminated ethanol more slowly, and had lower urine volume and sodium excretion than normal hamsters after ethanol injections. Plasma creatine kinase levels were normal in all animals tested, indicating no active skeletal or cardiac lesioning in the cardiomyopathic hamsters at the time of the experiment. Some factors which could contribute to the increased CNS and renal sensitivity to ethanol in cardiomyopathic hamsters include impaired ethanol metabolism, enhanced myocardial depression, and reduced atrial content of natriuretic peptides. The results do not owe to decompensated heart failure. Thus, the genetic mutation which causes skeletal and cardiac myopathy in these hamsters may also affect the metabolism and sensitivity to ethanol.
Alcoholic Intoxication↗
Sympathetic outflow to muscles during vasovagal syncope.
Sympathetic vasoconstrictor impulses were recorded with microelectrodes in peroneal muscle nerve fascicles during vasovagal syncope in two subjects. After a preceding period of increased nerve activity, onset of syncope was associated with bradycardia and sudden cessation of sympathetic outflow. The findings provide direct evidence that neurally mediated muscular vasodilatation occurring during syncope is due to inhibition of vasoconstrictor impulses.
Adult↗
Comparison of the postural tachycardia syndrome (POTS) with orthostatic hypotension due to autonomic failure.
Postural tachycardia syndrome (POTS) is characterized by orthostatic dizziness, tremulousness, tachycardia and variable blood pressure changes. Since some POTS patients have a marked reduction in pulse pressure on standing, a major mechanism of their symptoms might be venous pooling. We therefore studied the cardiovascular response to head-up tilt, Valsalva maneuver and deep breathing in: control subjects (n = 11; F = 8; M = 3; 39.2 +/- 14.4 years); patients with orthostatic hypotension secondary to autonomic failure (n = 11; F = 9; M = 2; 61.7 +/- 13.0 years), and patients with POTS (n = 15); F = 13; M = 2; 32.3 +/- 10.6 years). Blood pressure was measured with a Finapres, and cardiac output, stroke volume, end-diastolic volume and thoracic impedance (TFI) were measured by thoracic electrical bioimpedance. During tilt (in contrast to patients with orthostatic hypotensiom), patients with POTS had excessive tachycardia (P < 0.001), a normal to excessive total peripheral resistance increase, and an exaggerated decrease in stroke volume (P < 0.001) and end-diastolic volume (P < 0.001). These findings suggest that sympathetic arteriolar function remains relatively intact but that sympathetic venomotor function is selectively impaired. These findings may have significant implications for the treatment of patients with POTS.
Adult↗
Recovery of function after neonatal or adult hemispherectomy in cats: I. Time course, movement, posture and sensorimotor tests.
Cats with removal of the left hemitelencephalon (hemispherectomy) as neonates (n = 12) or in adulthood (n = 14), were compared using a battery of 16 neurological and behavioral tests given when they were young adults (kittens) or at least 5 months after the lesion (adults). The neonatal-lesioned subjects grew normally and performed markedly and significantly better than adult-lesioned cats in 13 tests covering the wide range of movement, posture and sensory functions which were assessed. None of the animals recovered tactile placing of the right forelimb or a normal vision in the right visual field. However, the overall recovery was outstanding for all cats such that the neonatal-lesioned were hard to differentiate from intact controls in their spontaneous, daily activities. Because the lesions were similar in the two age-at-lesion groups, and since numerous functions were followed for prolonged, comparable postlesion time, we conclude that, after hemispherectomy in the cat, there definitely is greater functional recovery if the lesion is sustained early in life. We propose that the enhanced recovery of function in neonatal-lesioned cats is largely due to the extensive anatomical reorganization which we have demonstrated in ongoing studies, and which contrasts with a lesser remodeling in adult-lesioned cats.
Age Factors↗
Natural history of global and critical brain ischaemia. Part III: cerebral prognostic signs after cardiopulmonary resuscitation. Cerebral recovery course and rate during the first year after global and critical ischaemia monitored and predicted by EEG and neurological signs.
The monitoring and predictive value of the electroencephalography (EEG) and neurological signs was evaluated in 125 patients who had sustained critical brain ischaemia during circulatory arrest of primary cardiovascular aetiology. Cranial nerve areflexia with mydriasis or extension of the upper limb in response to cutaneous stimulation reliably indicated brain death and appearance of the flexion reflex or of intermittent spikes and sharp waves in the EEG predicted an unfavourable outcome; but other EEG configurations and nuerological signs per se were inaccurate variables to assess the outcome. By contrast, the recovery course and rate were accurately assessed by the time for appearance of cerebral functions; the caloric vestibular reflex, decorticate posturing, stereotypic reactivity, intermittent and continuous electrocortical activity were regained within ultimate time limits of 900, 540, 455, 450, and 1020 min, respectively, corresponding to the longest delay compatible with recovery of function at all, and within critical time limits of 165, 180, 180, 200, and 630 min, respectively, corresponding to the longest delay compatible with recovery of consciousness. Moreover, intermittent electrocortical activity, consciousness, speech and ability to cope with personal necessities were regained within supercritical time limits of 3, 47, 156, and 336 h, respectively, corresponding to the longest delay compatible with complete restoration of post-awakening faculties within 1 year of resuscitation. Prognosis was currently ascertained during the period of unconsciousness as cephalic reactivities, and electrocortical activities were regained in an exponential relationship to time. Bradycardia or asystole prior to resuscitation and metabolic acidosis, hypotensive heart failure, recurrent circulatory arrest and pneumonia thereafter influenced the cerebral recovery adversely.
Brain Ischemia↗
The relationship between paraspinal EMG and chronic low back pain.
Two models of the relationship between paraspinal EMG and low back pain have been proposed. Specific predictions arising from these are listed and the literature relating to them reviewed. Recent research on patterns of EMG rather than absolute levels is also discussed. It is concluded that there is no consistent evidence that low back pain patients have elevated paraspinal EMG, or that its reduction is likely to be an active ingredient in biofeedback therapy. Research on paraspinal EMG patterns is still preliminary, and therefore treatment based on their modification is experimental.
Back Pain↗
Vestibular compensation: tonic spinal influence upon spontaneous descending vestibular nuclear activity.
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Animals↗
Response characteristics of cerebellar interpositus and intermediate cortex neurons to sinusoidal stimulation of neck and labyrinth receptors.
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Animals↗
Inhibition of alcohol dehydrogenase by chloral hydrate and trichloroethanol: possible role in the chloral hydrate-ethanol interaction.
Both chloral hydrate and trichloroethanol inhibited mouse liver alcohol dehydrogenase (LADH) in vitro. The inhibition of LADH by chloral hydrate appears to be non-competitive in nature with an inhibition constant (Ki) of about 2.7 X 10(-4) M. The inhibition of LADH by trichloroethanol was competitive and the (Ki) was about 2.7 X 10(-5) M. The elimination of ethanol from the blood and brain was significantly reduced in chloral hydrate- or trichloroethanol-pretreated mice. Since reduced elimination of ethanol could result in the prolongation of its central depressant activity, we suggest that this should be considered as a factor in the enhanced pharmacological effects of ethanol-chloral hydrate mixtures.
Alcohol Dehydrogenase↗
Temperature dependence of ethanol depression in C57BL/6 and BALB/c mice.
The relationship between environmental temperature, body temperature and brain sensitivity to ethanol was investigated in male C57BL/6S and BALB/cS mice. Age-matched, drug-naive mice of both strains were injected with 3.6 g/kg ethanol (20% w/v) and placed into a chamber kept at one of eight designated temperatures from 12 to 36 degrees C. Chamber temperature significantly affected wake-up rectal temperatures, sleep-times and wake-up brain ethanol concentrations in the intoxicated mice. Wake-up rectal temperatures were significantly, positively correlated with sleep-times and significantly, negatively correlated with wake-up brain ethanol concentrations in both strains. Linear regression analyses indicated that up to 47% of the variability in ethanol sensitivity of C57 mice and up to 31% of the variability in sensitivity of BALB mice could be accounted for by their wake-up rectal temperatures suggesting that the effects of ambient temperature on ethanol sensitivity were mediated, in part, by the resultant body temperatures. These results replicate and extend previous findings and demonstrate that temperature dependence of ethanol depression is not strain specific. The correlational and regression analyses provide additional evidence that brain sensitivity to ethanol depression varies with body temperature in accordance with membrane perturbation theories of anesthesia.
Animals↗
Automatic control of limb movement and posture.
Studies are reviewed that address the problem of the variables controlled by the central nervous system in the maintenance of body posture and limb movement against disturbing forces. The role of global variables of control, which take into account the dynamic state of the limb, is discussed. Neural substrates that are involved in the distributed control of kinematic and dynamic parameters are also considered.
Adaptation, Physiological↗
Improvement of a questionnaire measuring activity limitations in rising and sitting down in patients with lower-extremity disorders living at home.
OBJECTIVE: To improve a self-administered questionnaire that includes 42 dichotomous items and measures activity limitations in rising and sitting down (R&S) in patients with lower-extremity disorders who live at home. DESIGN: Cross-sectional study. SETTING: Outpatient clinics of secondary and tertiary care centers. PARTICIPANTS: Patients (N=759; 47% men; mean age +/- standard deviation, 60.7+/-15.2y) living at home, with lower-extremity disorders resulting from stroke, poliomyelitis, osteoarthritis, amputation, and complex regional pain syndrome type I. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: (1) Unidimensionality, indicating that items assess only a single construct; (2) fit with the one-parameter logistic model (OPLM), yielding information about patient and item location parameters; (3) intratest reliability, indicating consistency of patients' item scores; and (4) content validity, indicating completeness with which the items cover the important aspects of the construct that they are attempting to represent. RESULTS: Thirty-nine of 42 items: (1) loaded on 1 component (variance explained, 59%; item component loadings, >or=.51), (2) showed good fit with the OPLM (P=.15), (3) had a good intratest reliability (Cronbach alpha=.96), and (4) had a good content validity (all important aspects represented). CONCLUSIONS: A unidimensional scale that fits with the OPLM has been developed for measuring activity limitations in R&S in patients with lower-extremity disorders who live at home.
Activities of Daily Living↗
Effects of roll tilt on the direction of vertical postrotatory nystagmus in cats.
The rotation axis of horizontal postrotatory nystagmus (PRN) changes as the head is tilted, so that it becomes directed toward gravity (spatial reorientation). Here, we examined the vertical PRN orientation during roll tilt in cats. Unlike the case in horizontal PRN, in vertical PRN no significant cross-coupled components emerged to reorient the eyes toward gravity. Our results indicate that otolith input contributes differently to horizontal VOR than to vertical VOR.
Animals↗
Cervical muscle response to posterolateral impacts--effect of head rotation.
BACKGROUND: Rear impacts may be offset, and may also occur with the head rotated at impact. The purpose of this study was to determine the response of the cervical muscles to increasing low-velocity rear impacts offset by 45 degrees to the subject's right, but also with the head rotated either right or left. METHODS: Twenty healthy volunteers underwent right posterolateral impacts of 4.6, 8.0, 11.0, and 13.1 m/s2 acceleration with head turned right or left. Electromyograms of the sternocleidomastoids, trapezii, and splenii capitis were recorded, as were acceleration of the sled, torso, and head of the participant. FINDINGS: At an impact acceleration of 13.1 m/s2, with head rotated to the right, the left sternocleidomastoid and the contralateral (to rotation) trapezius and splenius capitis generated more electromyogram activity than their counterparts (P < 0.05). Following impacts with the head rotated to the right, the left sternocleidomastoid generated 67% of its maximal voluntary electromyogram, and the right sternocleidomastoid 5% of the maximal voluntary electromyogram, whereas the remaining muscles did not generate more than 31% of the maximal voluntary contraction electromyogram. In impacts with head rotated left, the right sternocleidomastoid generated 53% of its maximal voluntary electromyogram, and the left splenius capitis and left trapezius showed more electromyogram activity than their counterparts (P < 0.05). INTERPRETATION: Head rotation in a right posterolateral impact modifies the cervical response mainly by generating an asymmetry in the paired sternocleidomastoid electromyograms. This may asymmetrically affect the risk of injury to the sternocleidomastoids. An understanding of the muscular response to rear-impacts of different types and the effect of head rotation at the time of impact is relevant to understanding the mechanism of acute whiplash injury and may be helpful to develop targeted treatments and preventative measures.
Acceleration↗
Effects of different levels of torso coactivation on trunk muscular and kinematic responses to posteriorly applied sudden loads.
BACKGROUND: Studies examining rapid spine loading have documented the influence of steady-state trunk preloads, and the resulting levels of trunk muscle preactivation, on the control of spine stability. However, the effects of different levels of muscle coactivation, and resulting spine loads, on the response to a perturbation of the externally unloaded trunk are unclear. METHODS: Fourteen male subjects coactivated the abdominal muscles at four different levels (approximately 0%, 10%, 20% and 30% of the maximal voluntary contraction) monitored by an electromyography biofeedback system while semi-seated in a neutral lumbar spine position. They were loaded posteriorly in two directions (0 degrees and 30 degrees from the sagittal plane) and with two different loads (6.80 and 9.07 kg). Force perturbation, spine displacement and electromyography activity were measured, and torso compression and stability were modeled. FINDINGS: Abdominal coactivation significantly increased spine stability and reduced the movement of the lumbar spine after perturbation, but at the cost of increasing spinal compression. Preactivation also reduced the frequency and magnitude, and delayed the onset of muscle reactions, mainly for the back muscles and the internal oblique. The higher magnitude load and the load applied in an oblique direction both showed more potentially hazardous effects on the trunk. INTERPRETATION: Torso coactivation increases spinal stiffness and stability and reduces the necessity for sophisticated muscle responses to perturbation. Although further investigation is needed, it appears there is an asymptotic function between coactivation and both stiffness and stability. There also appears to be more hazard when buttressing twisting components of a sudden load compared to sagittal components. Patients with trunk instability and intolerance to spine compression may benefit from low to moderate levels of coactivation.
Abdominal Muscles↗