Modulation of tonic immobility in guinea pig PAG by homocysteic acid, a glutamate agonist

Tonic immobility (TI) is an innate defensive behavior elicited by physical restriction and postural inversion, and is characterized by a profound and temporary state of motor inhibition. The participation of the periaqueductal gray matter (PAG) in TI modulation has previously been described. In addition, the excitatory amino acids (EAA) are important mediators involved in the adjustment of several defensive responses produced by PAG. In the present study, we investigated the effect of microinjection of the EAA agonist DL-homocysteic acid (DLH) and the N-methyl-D-aspartate (NMDA) receptor antagonist (MK-801) into the ventrolateral and dorsal PAG over the duration of TI in guinea pigs. Microinjection of 15 nmol/0.2 mu l of DLH into the ventrolateral PAG (vlPAG) and 30 nmol/0.2 mu l of DLH into the dorsal PAG (dPAG) promoted an increase and decrease in TI duration, respectively. These responses were blocked by prior microinjection of the NMDA receptor antagonist, MK-801 (3.6 nmol/0.2 mu l) at the same site. Microinjection of MK-801 alone into the APAG and dPAG did not alter the duration of TI episodes. These results suggest that NMDA receptors are involved in the modulation of TI in both the vlPAG and dPAG. In addition, PAC excitatory amino acids modulate the TI response via columnar organization of the PAC. In this manner, the vlPAG facilitates TI modulation whereas dPAG has an inhibitory role in TI. (C) 2008 Elsevier Inc. All rights reserved.

GLOBAL POSTURAL REEDUCATION AND STATIC STRETCHING EXERCISES IN THE TREATMENT OF MYOGENIC TEMPOROMANDIBULAR DISORDERS: A RANDOMIZED STUDY

Objective: The purpose of this study was to compare 2 different interventions, global postural reeducation (GPR) and static stretching exercises (SS), in the treatment of women with temporomandibular disorders (TMDs). Methods: A total of 28 subjects with TMDs were randomized into 2 treatment groups: GPR, where therapy involved muscle global chain stretching, or SS, with conventional static stretching; but only 24 completed the study. Eight treatment sessions lasting 40 minutes each (weekly) were performed. Assessments were conducted at baseline, immediately after treatment end, and 2 months later. Measurements included pain intensity at the temporomandibular joint, headache, cervicalgia, teeth clenching, ear symptoms, restricted sleep, and difficulties for mastication, using a visual analogue scale. In addition, electromyographic activity and pain thresholds were measured at the masseter, anterior temporalis, stemocleidomastoid, and upper trapezius muscles. Two-way analysis of variance with Tukey post hoc test was used for between-group comparisons. Significance level was .05. Results: Comparing the pain assessments using the visual analogue scale, no significant differences were seen with the exception of severity of headaches at treatment end (GPR, 3.92 +/- 2.98 cm; SS, 1.64 +/- 1.66 cm; P < .024). In addition, no significant differences were seen for pain thresholds and for electromyographic activity (P > .05). Conclusions: For the subjects in this study, both GPR and SS were similarly effective for the treatment of TMDs with muscular component. They equally reduced pain intensity, increased pain thresholds, and decreased electromyographic activity. (J Manipulative Physiol Ther 2010;33:500-507)

Stability of anterior open-bite treatment with occlusal adjustment

Introduction: In this study, we aimed to evaluate the long-term stability of anterior open-bite treatment with occlusal adjustment and the dentinal sensitivity caused by this procedure in the long term. Methods: The sample comprised 17 open-bite patients who experienced relapse of the negative vertical overbite after orthodontic treatment and were retreated with occlusal adjustment. The cephalometric changes were evaluated on lateral cephalograms obtained before and after the occlusal adjustment and in the long term (mean, 3.4 years after occlusal adjustment). Dentinal sensitivity was also evaluated before the occlusal adjustment, and 1.35 months, 4.61 months, and 3.4 years later. The cephalometric statuses between the 3 evaluations were compared with analysis of variance (ANOVA) and Tukey tests. The percentages of clinically significant relapse were calculated. To compare dentinal sensitivity at the several stages, nonparametric Friedman and Wilcoxon tests were performed. Results: Statistically significant relapse of anterior open bite occurred in 33.3% of the patients. Those who had the procedure before 21 years of age were most likely to experience relapse. Dentinal sensitivity remained within the normal range in the long term. Conclusions: Despite the statistically significant relapse of anterior open bite, clinically significant stability was found in 66.7% of the patients. (Am J Orthod Dentofacial Orthop 2010; 138:14.e1-14.e7)

Evaluation of anterior open-bite treatment with occlusal adjustment

Introduction: The purpose of this study was to evaluate the cephalometric and occlusal changes, the functional occlusion, and the dentinal sensitivity of anterior open-bite treatment with occlusal adjustment. Methods: The sample comprised 20 patients who experienced relapse of the anterior open bite (mean, -1.06 mm). Occlusal adjustment was performed until a positive overbite was established. Cephalometric changes were evaluated on lateral cephalograms taken before and after the occlusal adjustment. The functional occlusion analysis consisted of evaluating immediate anterior and canine guidance and the number of teeth in contact before and after the procedure. Dentinal sensitivity was evaluated before, shortly after, and 4.61 months after the occlusal adjustment. Pretreatment and posttreatment cephalometric changes and the number of teeth in contact were compared with dependent t tests. Percentages of anterior and canine guidance before and after the adjustment procedure were compared with the McNemar test. To compare dentinal sensitivity at several stages, the nonparametric Friedman test was used, followed by the Wilcoxon test. Results: Significant increases in overbite and mandibular protrusion were seen, as were significant decreases in apical base discrepancy, facial convexity, and growth pattern angles. The percentages of immediate anterior and canine guidance increased significantly, as did the number of teeth with occlusal contacts. Dentinal sensitivity increased immediately after the adjustment but decreased to normal levels after 4.61 months. Conclusions: Occlusal adjustment is a viable treatment alternative for some open-bite patients; it establishes positive vertical overbite and improves the functional occlusion with only transient dentinal sensitivity.

The role of illness, resources, appraisal, and coping strategies in adjustment to HIV/AIDS: The direct and buffering effects

This study examined the utility of a stress and coping model of adjustment to HIV/AIDS. A total of 114 HN-infected gay or bisexual men were interviewed and they completed self-administered scales. Predictors included illness variables (disease stage and number of symptoms), coping resources (optimism and social support), appraisal (threat, challenge, and controllability), and coping strategies (problem-and emotion-focused). Adjustment outcomes were depression, global distress, social adjustment, and subjective health status. Results from hierarchical regression analyses indicated that better adjustment was related to an asymptomatic illness stage, fewer HN-related symptoms, greater social support, challenge and controllability appraisals, problem-focused coping, and lower threat appraisals and reliance on emotion focused coping. There was limited support for the stress-buffering effects of optimism. Findings support the utility of a stress and coping model of adjustment to HIV/AIDS.

Employee adjustment to an organizational merger: An intergroup perspective

Adopting an intergroup perspective, the research was designed to examine predictors of employee responses to an organizational merger Data were collected from 465 fleet staff employed in a newly merged airline company. As predicted from social identity theory, the negative effects of the merger were most marked for employees of the low-status premerger organization. Also, as predicted, the perception of permeable intergroup boundaries in the new organization was associated positively with identification with the new organization and both job-related and person-related outcomes among employees of the low-status premerger organization but negatively with person-related outcomes among employees of the high-status premerger organization. As predicted, there was some evidence that the main and interactive effects involving status, perceived permeability, and intergroup contact on employee adjustment were mediated through strength of identification with the new organization.

Changes in motor planning of feedforward postural responses of the trunk muscles in low back pain

Changes in trunk muscle recruitment have been identified in people with low-back pain (LBP). These differences may be due to changes in the planning of the motor response or due to delayed transmission of the descending motor command in the nervous system. These two possibilities were investigated by comparison of the effect of task complexity on the feedforward postural response of the trunk muscles associated with rapid arm movement in people with and without LBP. Task complexity was increased by variation of the expectation for a command to either abduct or flex the upper limb. The onsets of electromyographic activity (EMG) of the abdominal and deltoid muscles were measured. In control subjects, while the reaction time of deltoid and the superficial abdominal muscles increased with task complexity, the reaction time of transversus abdominis (TrA) was constant. However, in subjects with LBP, the reaction time of TrA increased along with the other muscles as task complexity was increased. While inhibition of the descending motor command cannot be excluded, it is more likely that the change in recruitment M of TrA represents a more complex change in organisation of the postural response.

Postural control of the trunk in response to lateral support surface translations during trunk movement and loading

The postural response to translation of the support surface may be influenced by the performance of an ongoing voluntary task. This study was designed to test this proposal by applying lateral perturbations while subjects handled a load in the frontal plane. Measurements were made of medio-lateral displacement of the centre of pressure, angular displacement of the trunk and thigh in the frontal plane and intra-abdominal pressure. Subjects were translated randomly to the left and right in a variety of conditions that involved standing either quietly or with a 5 kg load in their left hand, which they were required either to hold statically or to lift or lower. The results indicate that when the perturbation occurred towards the loaded left side the subjects were able to return their centre of pressure, trunk and thigh rapidly and accurately to the initial position. However, when the perturbation occurred towards the right (away from the load) this correction was delayed and associated with multiple changes in direction of movement, suggesting decreased efficiency of the postural response. This reduced efficiency can be explained by a conflict between the motor commands for the ongoing voluntary task and the postural response, and/or by the mechanical effect of the asymmetrical addition of load to the trunk.

Coexistence of stability and mobility in postural control: evidence from postural compensation for respiration

This study evaluated the extent to which movement of the lower limbs and pelvis may compensate for the disturbance to posture that results from respiratory movement of the thorax and abdomen. Motion of the neck, pelvis, leg and centre of pressure (COP) were recorded with high resolution in conjunction with electromyographic activity (EMG) of flexor and extensor muscles of the trunk and hip. Respiration was measured from ribcage motion. Subjects breathed quietly, and with increased volume due to hypercapnoca (as a result of breathing with increased dead-space) and a voluntary increase in respiration. Additional recordings were made during apnoea. The relationship between respiration and other parameters was measured from the correlation between data in the frequency domain (i.e. coherence) and from time-locked averages triggered from respiration. In quiet standing, small angular displacements (similar to0.5degrees) of the trunk and leg were identified in raw data. Correspondingly, there were peaks in the power spectra of the angular movements and EMG. While body movement and EMG were coherent with respiration (>0.5), the coherence between respiration and COP displacement was low (

Adjustment of homeless adolescents to a crisis shelter: Application of a stress and coping model

The present study examined the utility of a stress and coping model of adaptation to a homeless shelter among homeless adolescents. Seventy-eight homeless adolescents were interviewed and completed self-administered scales at Time 1 (day of shelter entry) and Time 2 (day of discharge). The mean duration of stay at the shelter was 7.23 days (SD = 7.01). Predictors included appraisal (threat and self-efficacy), coping resources, and coping strategies (productive, nonproductive, and reference to others coping). Adjustment outcomes were Time I measures of global distress, physical health, clinician-and youthworker- rated social adjustment, and externalizing behavior and Time 2 youthworker-rated social adjustment and goal achievement. Results of hierarchical regression analyses indicated that after controlling for the effects of relevant background variables (number of other shelters visited, sexual, emotional, and physical abuse), measures of coping resources, appraisal, and coping strategies evidenced distinct relations with measures of adjustment in ways consistent with the model's predictions with few exceptions. In cross-sectional analyses better Time I adjustment was related to reports of higher levels of coping resources, self-efficacy beliefs, and productive coping strategies, and reports of lower levels of threat appraisal and nonproductive coping strategies. Prospective analyses showed a link between reports of higher levels of reference to others coping strategies and greater goal achievement and, unexpectedly, an association between lower self-efficacy beliefs and better Time 2 youthworker-rated social adjustment. Hence, whereas prospective analyses provide only limited support for the use of a stress and coping model in explaining the adjustment of homeless adolescents to a crisis shelter, cross-sectional findings provide stronger support.