Consistent Asymmetries Research Articles

Bilateral Asymmetry of Spatiotemporal Running Gait Parameters in U14 Athletes at Different Speeds.

The assessment of leg asymmetries is gaining scientific interest due to its potential impact on performance and injury development. Athletes around puberty exhibit increased gait variability due to a non-established running pattern. This study aims to describe the asymmetries in the spatiotemporal running parameters in developmentally aged athletes. Forty athletes under 14 (U14) (22 females and 18 males) were assessed running on a treadmill at constant speeds of 12 and 14 km·h-1 for 3 min. Step length, step frequency, along with contact (CT) and flight time, both in absolute values and as a percentage of step time, were recorded using a RunScribe sensor attached to the laces of each shoe. U14 runners exhibited high bilateral symmetry in the spatiotemporal parameters of running, with mean asymmetry values (1-5.7%) lower than the intra-limb coefficient of variation (1.7-9.6%). Furthermore, bilateral asymmetries did not vary between the two speeds. An individual-based interpretation of asymmetries identified subjects with consistent asymmetries at both speeds, particularly in terms of CT and contact ratio (%, CT/step time). This study confirms the high symmetry of pubertal runners and paves the way for the application of portable running assessment technology to detect asymmetries on an individual basis.

Between-session reliability of dry-land and in-water tests to measure inter-limb asymmetries in swimmers

ABSTRACT The aims of the present study were to: i) analyse the between-session reliability of dry-land and in-water swimming tests, and ii) investigate the prevalence of meaningful asymmetries in swimming athletes. Twenty-eight swimmers (21 males, 7 females) performed anthropometric, shoulder range of motion (ROM), countermovement jump, shoulder isokinetic torque, and 15-s tethered swimming tests two times, 1 week apart. Inter-limb asymmetries were calculated for each variable. Raw data reliability was determined using the intraclass coefficient correlation (ICC) and the typical error of measurement (TEM), and effect size (ES) was used to determine systematic bias between test sessions. At an individual level, inter-limb asymmetries were compared to the coefficient of variation (CV) to determine whether they were real. The between-session reliability was good to excellent (0.75 to 1.00) for most of the raw data, except for ROM. Between-session ES was predominately “trivial” or “small” for raw data and asymmetries, reinforcing that the values did not change significantly between the sessions. In addition, real asymmetries were seen in some tested metrics, depending on the test. In conclusion, the tested variables presented good levels of between-session reliability and were able to detect real and consistent asymmetries.

Using Electric Stimulation of the Spinal Muscles and Electromyography during Motor Tasks for Evaluation of the Role in Development and Progression of Adolescent Idiopathic Scoliosis.

Introduction: The role of the spinal muscles in scoliogenesis is not fully substantiated. Do they act scoliogenic (inducing scoliosis) or counteract scoliosis in adolescent idiopathic scoliosis (AIS)? In this study, we will examine this by using selectively placed Transcutaneous Electric Stimulation (TES) combined with a cinematic radiographic technique and by performing electromyographic (EMG) evaluations during various motor tasks. Method: This is a cross-sectional study of subjects with small-curve AIS. Using cinematic radiography, they were evaluated dynamically either under electrical stimulation or when performing motor tasks of left and right lateral bending and rotation whilst measuring the muscle activity by EMG. Results: Forty-five patients with AIS were included as subjects. Five subjects volunteered for TES and six subjects performed the motor tasks with EMG. At the initial visual evaluation, and when stimulated with TES, the frontal plane spatial positions of the vertebral bodies showed discrete changes without an apparent pattern. However, analyzing the spatial positions when calibrated, we found that the spinal muscles exert a compressive 'response' with a minor change in the Cobb angle (CA) in small-curve AIS (CA = 10-20°). In larger curves (CA > 20°), TES induced a 'larger deformity' with a relative four-fold change in the CA compared to small-curve AIS with a ratio of 0.6. When evaluating local amplitude (peak) or cumulative (mean) EMG signals, we were unable to find consistent asymmetries. However, one subject had rapid progression and one regressed to a straight spine. When adding the absolute EMG ratios for all four motor tasks, the subject with progression had almost 10-fold less summed EMG ratios, and the subject with regression had more than 3-fold higher summed EMG ratios. Discussion: Based on these findings, we suggest that the spinal muscles in small-curve AIS have a stabilizing function maintaining a straight spine and keeping it in the midline. When deformities are larger (CA > 20°), the spine muscle curve exerts a scoliogenic 'response'. This suggests that the role of the muscles converts from counteracting AIS and stabilizing the spine to being scoliogenic for a CA of more than 20°. Moreover, we interpret higher EMG ratios as heightened asymmetric spinal muscle activity when the spinal muscles try to balance the spine to maintain or correct the deformity. When progression occurs, this is preceded or accompanied by decreased EMG ratios. These findings must be substantiated by larger studies.

EEG asymmetry detection in patients with severe acquired brain injuries via machine learning methods

Lateral brain symmetry indexes, detected by electroencephalography (EEG), are markers of rehabilitative recovery widely used in patients with severe acquired brain injury (sABI). In this study, Machine Learning algorithms were cross-validated to detect consistent asymmetries, starting from a completely automated features extraction pipeline in the EEG recordings of 54 patients with sABI, classified by two expert neurophysiologists. Raw data were filtered and segmented in two-seconds non-overlapping epochs. Low data quality in frontal electrodes caused up to 40% of epochs rejection, whilst central and posterior electrodes contributed with the greatest number of artefacts-free epochs. Out of more than 3000 extracted features, ∼300 significantly differentiated symmetric and asymmetric EEG recordings, most of them extracted from pairs and lines of electrodes. The best performing solution (nested-cross-validated and optimized Support Vector Machine classifier) detected asymmetry with a test accuracy of 85% (sensitivity 92%, specificity 80%). The application of the proposed approach to our sample size supports the generalizability of our model and its translation to clinical practice. The algorithm, heading to automatic EEG analysis, has the potential to speed up analysis of long recordings and, to improve quality of care in settings lacking skilled staff.

Nervous System Involvement in Coronavirus Disease 2019: Results from a Retrospective Consecutive Neuroimaging Cohort.

BackgroundNeurological complications in coronavirus disease 2019 (COVID-19) have been described, but the understanding of their pathophysiology and neuroanatomical correlates remains limited.PurposeTo report on the frequency and type of neuroradiological findings in COVID-19.Materials and MethodsIn this retrospective study, all consecutive adult hospitalized patients with PCR-positivity for SARS-CoV-2, undergoing neuroimaging at Karolinska University Hospital between March 2 and May 24, 2020, were included. All examinations were systematically re-evaluated by 12 readers. Summary descriptive statistics were calculated.Results185 patients with COVID-19 (62±14 years, 138 men) underwent neuroimaging. In total, 222 brain CT, 47 brain MRI and 7 spinal MRI scans were performed. Intra-axial susceptibility abnormalities were the most common finding (29 of 39 [74%, 95%-CI 58–87%]) in patients with brain MRI, often with an ovoid shape suggestive of microvascular pathology, and with a predilection to corpus callosum (23 of 39, [59%, 95%-CI 42–74%]) and juxtacortical areas (14 of 39, [36%, 95% CI 21-53%]). Ischemic and macrohemorrhagic manifestations were also seen, but vascular imaging did not reveal overt abnormalities. Dynamic susceptibility contrast perfusion MRI in 19 patients did not reveal consistent asymmetries between hemispheres or regions. Many patients (18 of 41 [44%, 95%-CI 28–60%]) had leukoencephalopathy and one patient had a cytotoxic lesion of the corpus callosum. Other findings included olfactory bulb signal abnormalities (7 of 37, 19%), prominent optic nerve subarachnoid spaces (20 of 36, 56%), and enhancement of the parenchyma (3 of 20, 15%), leptomeninges (3 of 20, 15%), cranial nerves (2 of 20, 10%), and spinal nerves (2 of 4, 50%). At MRI follow-up, regression of leukoencephalopathy and progressive leptomeningeal enhancement was observed in one patient respectively, suggestive of dynamic processes.ConclusionPatients with COVID-19 had a wide spectrum of vascular and inflammatory involvement of both the central and peripheral nervous system.

Efficient Coding by Midget and Parasol Ganglion Cells in the Human Retina

In humans, midget and parasol ganglion cells account for most of the input from the eyes to the brain. Yet, how they encode visual information is unknown. Here, we perform large-scale multi-electrode array recordings from retinas of treatment-naive patients who underwent enucleation surgery for choroidal malignant melanomas. We identify robust differences in the function of midget and parasol ganglion cells, consistent asymmetries between their ON and OFF types (that signal light increments and decrements, respectively) and divergence in the function of human versus non-human primate retinas. Our computational analyses reveal that the receptive fields of human midget and parasol ganglion cells divide naturalistic movies into adjacent spatiotemporal frequency domains with equal stimulus power, while the asymmetric response functions of their ON and OFF types simultaneously maximize stimulus coverage and information transmission and minimize metabolic cost. Thus, midget and parasol ganglion cells in the human retina efficiently encode our visual environment.

A resident-nepotistic-tolerant dominance style in wild white-nosed coatis (Nasua narica)?

Abstract Dominance relationships imply consistent asymmetries in social relationships. Socioecological models predict that resource distribution determines the mode of competition that animals will face and, ultimately, the nature of their social relationships. Here, we provide the first systematic investigation of dominance style in white-nosed coatis (Nasua narica). Coatis live in cohesive female-resident groups, and have a diet based on clumped (fruits) and dispersed (insects) food items, which are predicted to favour despotic and egalitarian social styles, respectively. Our results revealed moderate linearity and steepness in dominance relationships over time, with variations attributed to stages of reproductive season, rather than presumed variations in food resources. Primary social bonds and coalitions were found to mediate dominance rank. Overall, our results suggest some similarities between coatis and despotic-tolerant primate species, at least under particular ecological circumstances, and we discuss their potential for affording a deeper understanding on the sources of variation in mammal social systems.

Generalized nonmotor (absence) seizures-What do absence, generalized, and nonmotor mean?

Clinical absences are now classified as "generalized nonmotor (absence) seizures" by the International League Against Epilepsy (ILAE). The aim of this paper is to critically review the concept of absences and to put the accompanying focal and motor symptoms into the context of the emerging pathophysiological knowledge. For this narrative review we performed an extensive literature search on the term "absence," and analyzed the plethora of symptoms observed in clinical absences. Arising from the localization and the involved cortical networks, motor symptoms may include bilateral mild eyelid fluttering and mild myoclonic jerks of extremities. These motor symptoms may also occur unilaterally, analogous to a focal motor seizure with Jacksonian march. Furthermore, electroencephalography (EEG) abnormalities may exhibit initial frontal focal spikes and consistent asymmetries. Electroclinical characteristics support the cortical focus theory of absence seizures. Simultaneous EEG/functional magnetic resonance imaging (fMRI) measurements document cortical deactivation and thalamic activation. Cortical deactivation is related to slow waves and disturbances of consciousness of varying degrees. Motor symptoms correspond to the spike component of the 3/s spike-and-wave-discharges. Thalamic activation can be interpreted as a response to overcome cortical deactivation. Furthermore, arousal reaction during drowsiness or sleep triggers spikes in an abnormally excitable cortex. An initial disturbance in arousal mechanisms ("dyshormia") might be responsible for the start of this abnormal sequence. The classification as "generalized nonfocal and nonmotor (absence) seizure" does not covey the complex semiology of a patient's clinical events.

Limb dominance, foot orientation and functional asymmetry during walking gait

While healthy gait is often characterized as, or assumed to be symmetric, consistent asymmetries often exist. In this study, we test the hypotheses that asymmetries in lower limb function, as measured by ground reaction force characteristics, may be explained by differences in foot orientation or limb dominance. Peak ground reaction force (GRF) measurements, and impulses were obtained for thirty-six healthy subjects with simultaneous kinematic estimates of foot posture. Three gait tasks were performed: subjects walked i) with normal foot orientation, ii) with feet laterally rotated (outward), and iii) with feet aligned in the direction of movement (straight). All subjects reported right limb dominance. Our results indicate that vertical, braking and propulsive GRF components are largely symmetrical, but significant asymmetries exist in the mediolateral peak forces and impulses with higher lateral and lower medially-directed GRF components being generated by the dominant right limbs. While foot orientations used during the different tasks do explain some differences in mediolateral peak forces and impulses, foot orientation did not explain this variation within normal walking. We conclude that limb dominance is a better predictor of asymmetry in force generation than foot posture.

Cone-Beam Computed Tomography Assessment of Lower Facial Asymmetry in Unilateral Cleft Lip and Palate and Non-Cleft Patients with Class III Skeletal Relationship.

IntroductionTo evaluate, using cone-beam computed tomography (CBCT), both the condylar-fossa relationships and the mandibular and condylar asymmetries between unilateral cleft lip and palate (UCLP) patients and non-cleft patients with class III skeletal relationship, and to investigate the factors of asymmetry contributing to chin deviation.MethodsThe UCLP and non-cleft groups consisted of 30 and 40 subjects, respectively, in mixed dentition with class III skeletal relationships. Condylar-fossa relationships and the dimensional and positional asymmetries of the condyles and mandibles were examined using CBCT. Intra-group differences were compared between two sides in both groups using a paired t-test. Furthermore, correlations between each measurement and chin deviation were assessed.ResultsIt was observed that 90% of UCLP and 67.5% of non-cleft subjects had both condyles centered, and no significant asymmetry was found. The axial angle and the condylar center distances to the midsagittal plane were significantly greater on the cleft side than on the non-cleft side (P=0.001 and P=0.028, respectively) and were positively correlated with chin deviation in the UCLP group. Except for a larger gonial angle on the cleft side, the two groups presented with consistent asymmetries showing shorter mandibular bodies and total mandibular lengths on the cleft (deviated) side. The average chin deviation was 1.63 mm to the cleft side, and the average absolute chin deviation was significantly greater in the UCLP group than in the non-cleft group (P=0.037).ConclusionCompared with non-cleft subjects with similar class III skeletal relationships, the subjects with UCLP showed more severe lower facial asymmetry. The subjects with UCLP presented with more asymmetrical positions and rotations of the condyles on axial slices, which were positively correlated with chin deviation.

Transcript Profiling of Individual Twin Blastomeres Derived by Splitting Two-Cell Stage Murine Embryos1

In invertebrates and amphibians, informational macromolecules in egg cytoplasm are organized to provide direction to the formation of embryonic lineages, but it is unclear whether vestiges of such prepatterning exist in mammals. Here we examined whether twin blastomeres from 2-cell stage mouse embryos differ in mRNA content. mRNA from 26 blastomeres derived from 13 embryos approximately mid-way through their second cell cycle was subjected to amplification. Twenty amplified samples were hybridized to arrays. Of those samples that hybridized successfully, 12 samples in six pairs were used in the final analysis. Probes displaying normalized values >0.25 (n = 4573) were examined for consistent bias in expression within blastomere pairs. Although transcript content varied between both individual embryos and twin blastomeres, no consistent asymmetries were observed for the majority of genes, with only 178 genes displaying a >1.4-fold difference in expression across all six pairs. Although class discovery clustering showed that blastomere pairs separated into two distinct groups in terms of their differentially expressed genes, when the data were tested for significance of asymmetrical expression, only 39 genes with >1.4-fold change ratios in six of six blastomere pairs passed the two-sample t-test (P < 0.05). Transcripts encoding proteins implicated in RNA processing and cytoskeletal organization were among the most abundant, differentially distributed mRNA, suggesting that a stochastically based lack of synchrony in cell cycle progression between the two cells might explain at least some and possibly all of the asymmetries in transcript composition.

What Type of Disputes are Best Suited for Alternative Dispute Resolution -An Analysis in the Space of the Odds of Litigation

This paper performs an analysis of litigation from the perspective of behavioural law and economics. It investigates the conditions that facilitate or prevent resolution of legal conflicts. The main focus is on the effects of the risk-seeking/aversion tendencies of the parties (and the optimism bias), in accordance with the cognitive-behaviouristic approach in the field. The main hypothesis of this paper is that, in contrast with the common view, the risk-seeking tendency in itself is not a barrier to a resolution of legal conflicts. The real difficulty lies in consistent asymmetries in the risk tendency of the parties. This hypothesis is tested by theoretical as well as experimental research. Finally, an attempt is made to draw the normative conclusions that follow from the obtained results.

Eye regeneration assay reveals an invariant functional left-right asymmetry in the early bilaterian, Dugesia japonica.

Consistent visceral asymmetry in vertebrates raises fascinating questions about the developmental mechanisms and evolutionary origin of fixed chirality of the left-right axis. One persistent controversy is whether consistently biased asymmetry is a later innovation imposed on a bilaterally symmetrical primitive body-plan, or whether asymmetry is a fundamental property predating the bilateria. The morphology of planaria suggests proximity to the origin of the bilateral body-plan, and they are commonly thought to be left-right symmetrical, as no consistent anatomical asymmetries have been described despite over a century of study of regeneration. Here, we show that D. japonica possess a consistent functional asymmetry in eye patterning defects caused by inhibition of H+/K+-ATPase activity (an ion flux mechanism recently shown to be an important early step in the asymmetry of several vertebrate embryos). Moreover, an endogenous transcript of the non-gastric H+/K+-ATPase subunit alpha is expressed in the head blastema shortly after amputation. Taken together, these data suggest that left-right asymmetry is at least as old as planaria, subtle functional asymmetries should be sought in other more primitive model systems that are believed to be symmetrical, and symmetrical paired structures may in fact contain information about their position on the L or R side.

The embryonic origins of left-right asymmetry.

The bilaterally symmetric body plan of vertebrates features several consistent asymmetries in the placement, structure, and function of organs such as the heart, intestine, and brain. Deviations from the normal pattern result in situs inversus, isomerisms, or heterotaxia (independent randomization), which have significant clinical implications. The invariance of the left-right (LR) asymmetry of normal morphology, neuronal function, and phenotype of several syndromes raises fascinating and fundamental questions in cell, developmental, evolutionary, and neurobiology. While a pathway of asymmetrically expressed signaling factors has been well-characterized in several model systems, very early steps in the establishment of LR asymmetry remain poorly understood. In particular, the origin of consistently oriented asymmetry is unknown. Recently, a candidate for the origins of asymmetry has been suggested: bulk transport of extracellular morphogens by rotating primary cilia during gastrulation. This model is appealing because it 'bootstraps' morphological asymmetry of the embryo from the intrinsic structural (molecular) chirality of motile cilia. However, conceptual and practical problems remain with this hypothesis. Indeed, the genetic data are also consistent with a different mechanism: cytoplasmic transport roles of motor proteins. This review outlines the progress and remaining questions in the field of left-right asymmetry, and focuses on an alternative model for 'Step 1' of asymmetry. More specifically, based on wide-ranging data on ion fluxes and motor protein function in several species, it is suggested that laterality is driven by pH/voltage gradients across the midline, which are established by chiral movement of motor proteins with respect to the cytoskeleton.

Divergent Systems of Agonistic Behaviour in Lemurid Primates

AbstractTwo semifree-ranging groups of ringtailed lemurs (Lemur catta) and two co-ranging groups of redfronted lemurs (Eulemur fulvus rufus) were studied across a two-year period to characterise and contrast the adult agonistic behaviour these primates exhibit within groups. Temporal analyses of behavioural data distinguished agonistic from non-agonistic behaviour and aggressive from submissive behaviour. The ringtailed lemurs employed a diverse repertoire of behavioural elements to communicate agonistic intent. More than 50% of these elements were signals and nearly 50% of signals were submissive. The agonistic repertoire of the redfronted lemurs, by contrast, was relatively unelaborated: less than 40% of agonistic behaviour in this species comprised signals and less than 20% of signals were submissive. These structural differences underlay marked species differences in agonistic interaction and relationship. All pairs of ringtailed lemurs maintained dominance relations resembling those seen in many anthropoid primates: subordinates consistently signalled submissively to dominant partners, often in the absence of aggression. Dominance relations among members of each sex were seasonally unstable and not always transitive (hierarchical) during periods of stability, however. Redfronted lemurs, by contrast, did not maintain dominance relations, failing to respond agonistically to most aggression received (52% of interactions) and responding with aggression on many other occasions (12%). Even applying relaxed criteria, few adult redfronted dyads (14%) showed consistent asymmetries in agonistic relations and several never exhibited any asymmetry. Lacking dominance, E. f rufus relied heavily on alternate behavioural mechanisms to moderate social conflict as frequent and intense as that seen in study groups of ringtailed lemurs. These included a great inclination not to respond agonistically to aggression, a distinctive behavioural proposal to limit or terminate dyadic conflict (Look away), post-conflict reconciliation, and relatively frequent third-party aggression. The existence of such divergent systems of agonistic behaviour in partially sympatric, closely related and generally similar prosimian primates offers important opportunities for comparative study of the ecology, development, and evolution of mammalian social systems. Future research may reveal ecophysiological factors that promote the use of dominance behaviour among like-sexed ringtailed lemurs and show how the relative absence of dominance relates to other major elements of redfronted lemur biology, including 'special relationships' of variable duration between adult males and females.

Exteroceptive Suppression of Temporalis Muscle Activity: A Blind Study of Tension‐Type Headache, Migraine, and Cervicogenic Headache

Exteroceptive suppression of temporalis muscle activity (ES2 duration) has been reported to be reduced in chronic tension-type headache in previous open studies (with varying stimulus and analysis methods). We studied ES2 duration and latency in 11 patients with chronic tension-type headache, 10 patients with cervicogenic headache, 11 migraine patients, and 9 headache-free control subjects. The investigator was blinded as to the diagnostic category. Electrical stimuli of 0.5 ms duration and at least three times sensory threshold (median 9.6 mA) were used. ES2 was obtained in all but one (control) subject and the control ES2 duration mean was 33.5 (SD 8.5) ms (80% EMG amplitude reduction criterion). Mean ES2 duration differences were not found between the four groups. None of the headache patients had ES2 durations below the control group range. ES2 duration tended to decrease with increasing duration of headache history. Consistent asymmetries of ES2 latency and duration were not found among patients with (unilateral) cervicogenic headache. Thus, the role of ES2 in headache diagnosis still seems to be unsettled.

Visible burrow system as a model of chronic social stress: Behavioral and neuroendocrine correlates

In mixed-sex rat groups maintained in visible burrow systems (VBS), consistent asymmetries in offensive and defensive behaviors of male dyads are associated with the development of dominance hierarchies. Subordinate males are characterized by particular wound patterns, severe weight loss, and a variety of behavioral changes, many of them isomorphic to target symptoms of clinical depression. In two VBS studies, subordinate males showed increased basal levels of plasma corticosterone (CORT), and increased adjusted adrenal and spleen weights compared to controls, and often, to dominants as well. Thymus weights and testosterone levels of subordinates were not reliably different in one study using highly aggressive males, but were reduced, along with testes weights, in a second study using unselected males. Glucocorticoid receptor binding levels in hippocampus, hypothalamus, and pituitary were not different, nor were aldosterone levels. When tested in a restraint stress procedure, subordinates had higher basal CORT levels, but about 40% of these animals showed a reduced, or absent, CORT response to restraint. These findings indicate that subordination may be reflected in high magnitude changes consistent with physiological indices of prolonged stress. Dominant rats of such groups may also show physiological changes suggesting stress, particularly when the groups are comprised of highly aggressive males only. The VBS colony model thus appears to enable rat groups to produce natural, stress-engendering, social interactions that constitute a particularly relevant model for investigating the behavioral, neural, and endocrine correlates of chronic stress.

Quantification of opiate receptors in two patients with mesiobasal temporal lobe epilepsy, before and after selective amygdalo- hippocampectomy, using positron emission tomography

Using PET, reduced glucose metabolism (rCMRglu) and increased binding of the mu opiate receptor ligand 11C-carfentanil have been demonstrated in lateral temporal cortex overlying mesial temporal epileptic foci. Binding of the non-specific opiate receptor ligand 11C-diprenorphine (DPN) to lateral temporal cortex has not shown consistent asymmetries. We measured rCMRglu with 18F-FDG and binding of 11C-diprenorphine in two patients with temporal lobe epilepsy (TLE) before and 5 months after selective amygdalo-hippocampectomy (both patients were seizure-free post-operatively). Pre-operatively, in both patients rCMRglu was decreased in mesial temporal lobe (MTL) (asymmetry index AI = −9.1 and 9.0) ipsilateral to the EEG focus. A more marked reduction was seen in ipsilateral lateral temporal cortex (LTC) ( AI = −32.0 and 18.9). DPN binding was reduced in MTL and LTC ( AI MTL = −9.3 and 16.2; AI LTC = −8.0 and 5.5) ipsilateral to the focus, but was within 2 SD of the normal range. Post-operatively, the reduction of rCMRglu in LTC was accentuated in one patient and decreased in the other ( AI = −23.1 and 45.7) while there was a further reduction of DPN binding in LTC in both patients ( AI = −27.8 and 9.8). These preliminary results in only two patients are compatible with downregulation of opiate receptors in LTC after removal of the epileptic focus or post-operative neuronal dysfunction.

Subordination stress: behavioral, brain, and neuroendocrine correlates.

In mixed-sex rat groups consistent asymmetries in offensive and defensive behaviors of male dyads are associated with the development of dominance hierarchies. Subordinate males can be differentiated from dominants on the basis of both agonistic and non-agonistic behaviors, wound patterns, weight changes. Their behavior changes suggest chronic defensiveness and are also broadly isomorphic to many of the symptoms of depression; their voluntary alcohol consumption increases, and their life-spans are shortened. Both subordinate and dominant males tend to show organ change compared to non-grouped controls, with adrenal and spleen enlargement and thymus reduction. However, these changes appear to be more marked in subordinates, and only subordinates show reduced testes weights. Basal corticosterone (CORT) levels were sharply higher, and plasma testosterone (T) sharply lower, in subordinates compared to both dominants and controls, and reduced corticosterone binding globulin further enhanced free CORT for subordinates particularly. Many subordinates failed to show a normal CORT response to restraint stress. Subordinates also appear to show widespread changes in serotonin systems, with increased 5-HIAA/5-HT ratios in a number of brain areas, and alterations of 5-HT1A receptor binding at some sites. These changes suggest that subordination, a common and consistent feature of life for many animals living in social groups, may be a particularly relevant model for investigating the behavioral, neural and endocrine correlates of chronic stress.

Gait adaptations of young adult females to hand-held loads determined from ground reaction forces

Abstract Although walking with hand-held loads is a fairly mundane activity performed by all sections of the ambulant population, very few studies have been made of the possible consequences for the gait. In this study we investigated a group of young adult females while walking without load, asymmetrically loaded with 15% body weight either in the left hand or in the right hand, or symmetrically loaded with 15% body weight in each hand. Walking speed over a distance of 3.5 m was measured, together with data from two force plates. The latter were used to determine durations of the walking cycle and its phases. The ground reaction forces were incorporated in simple equations of motion to determine the oscillations of movement of the centre of mass of the body, or body plus load, during the walking cycle. Group mean values of measurements made in the loaded situations were compared with the corresponding values for the unloaded situation. Values obtained for the asymmetric loading were used to investigate the effects upon gait symmetry. Our main findings were that loading tended to decrease the cycle duration, increase double support and decrease single stance phase, but the stance phase was not affected. The amplitudes of the lateral and fore-aft oscillations of the centre of mass were reduced by loading. Consistent asymmetries were seen in the body centre of mass oscillations as a result of asymmetric loading. Where comparisons are possible, our results tend to match those of other authors who performed studies under other sorts of loading conditions. The overall conclusion is that the changes even when significant are quite small, indicating that the gait adapts well to loading, at least for the group of subjects we studied and for the loads we used.