Atividade muscular da mastigação na anquilose temporomandibular

Purpose: due to the presence of major masticatory dysfunction in patients with temporomandibular joint (TMJ) ankylosis, this study analyzed mouth opening and EMG activity of masticatory muscles in order to detect changes in these parameters after surgical release of mandible ankylosis. Method: in 7 patients with temporomandibular ankylosis, between 7 and 30 years (median = 9 years), the distance was measured as interincisal maximum active (DIMA) and we recorded the electromyographic activity (EMG) of masseter and temporal muscles during voluntary isometric contraction (VIC) and chewing, comparing the data before and after surgery using the Wilcoxon test. Results: higher values were observed for DIMA after surgery (p=0.0277), the asymmetry index showed no difference between the two evaluated periods for both studied muscles, the values of the EMG during VIC decreased after surgery for the right (p=0.0179) and left (p=0.0179) masseter but not for the temporal muscle, there were no changes in EMG values for the studied muscles during mastication. Conclusion: the surgical release of TMJ ankylosis resulted in an increase of mouth opening and decreased amplitude of action potentials generated during maximum isometric voluntary contraction of the masseter muscle on both sides, this did not change the asymmetry index of the masseter and temporal as well as the electromyographic activity of the temporal muscle bilaterally during isometric contraction and masseter and temporal muscles during mastication.

Leg and arm lactate and substrate kinetics during exercise

[EN] To study the role of muscle mass and muscle activity on lactate and energy kinetics during exercise, whole body and limb lactate, glucose, and fatty acid fluxes were determined in six elite cross-country skiers during roller-skiing for 40 min with the diagonal stride (Continuous Arm + Leg) followed by 10 min of double poling and diagonal stride at 72-76% maximal O(2) uptake. A high lactate appearance rate (R(a), 184 +/- 17 micromol x kg(-1) x min(-1)) but a low arterial lactate concentration ( approximately 2.5 mmol/l) were observed during Continuous Arm + Leg despite a substantial net lactate release by the arm of approximately 2.1 mmol/min, which was balanced by a similar net lactate uptake by the leg. Whole body and limb lactate oxidation during Continuous Arm + Leg was approximately 45% at rest and approximately 95% of disappearance rate and limb lactate uptake, respectively. Limb lactate kinetics changed multiple times when exercise mode was changed. Whole body glucose and glycerol turnover was unchanged during the different skiing modes; however, limb net glucose uptake changed severalfold. In conclusion, the arterial lactate concentration can be maintained at a relatively low level despite high lactate R(a) during exercise with a large muscle mass because of the large capacity of active skeletal muscle to take up lactate, which is tightly correlated with lactate delivery. The limb lactate uptake during exercise is oxidized at rates far above resting oxygen consumption, implying that lactate uptake and subsequent oxidation are also dependent on an elevated metabolic rate. The relative contribution of whole body and limb lactate oxidation is between 20 and 30% of total carbohydrate oxidation at rest and during exercise under the various conditions. Skeletal muscle can change its limb net glucose uptake severalfold within minutes, causing a redistribution of the available glucose because whole body glucose turnover was unchanged.

The language of others mirrored in thy face: The role of political affiliation in automatic facial effects of language

People tend to automatically mimic facial expressions of others. If clear evidence exists on the effect of non-verbal behavior (emotion faces) on automatic facial mimicry, little is known about the role of verbal behavior (emotion language) in triggering such effects. Whereas it is well-established that political affiliation modulates facial mimicry, no evidence exists on whether this modulation passes also through verbal means. This research addressed the role of verbal behavior in triggering automatic facial effects depending on whether verbal stimuli are attributed to leaders of different political parties. Study 1 investigated the role of interpersonal verbs, referring to positive and negative emotion expressions and encoding them at different levels of abstraction, in triggering corresponding facial muscle activation in a reader. Study 2 examined the role of verbs expressing positive and negative emotional behaviors of political leaders in modulating automatic facial effects depending on the matched or mismatched political affiliation of participants and politicians of left-and right-wing. Study 3 examined whether verbs expressing happiness displays of ingroup politicians induce a more sincere smile (Duchenne) pattern among readers of same political affiliation relative to happiness expressions of outgroup politicians. Results showed that verbs encoding facial actions at different levels of abstraction elicited differential facial muscle activity (Study 1). Furthermore, political affiliation significantly modulated facial activation triggered by emotion verbs as participants showed more congruent and enhanced facial activity towards ingroup politicians’ smiles and frowns compared to those of outgroup politicians (Study 2). Participants facially responded with a more sincere smile pattern towards verbs expressing smiles of ingroup compared to outgroup politicians (Study 3). Altogether, results showed that the role of political affiliation in modulating automatic facial effects passes also through verbal channels and is revealed at a fine-grained level by inducing quantitative and qualitative differences in automatic facial reactions of readers.

Influence of optic flow on postural control

The study of optic flow on postural control may explain how self-motion perception contributes to postural stability in young males and females and how such function changes in the old falls risk population. Study I: The aim was to examine the optic flow effect on postural control in young people (n=24), using stabilometry and surface-electromyography. Subjects viewed expansion and contraction optic flow stimuli which were presented full field, in the foveral or in the peripheral visual field. Results showed that optic flow stimulation causes an asymmetry in postural balance and a different lateralization of postural control in men and women. Gender differences evoked by optic flow were found both in the muscle activity and in the prevalent direction of oscillation. The COP spatial variability was reduced during the view of peripheral stimuli which evoked a clustered prevalent direction of oscillation, while foveal and random stimuli induced non-distributed directions. Study II was aimed at investigating the age-related mechanisms of postural stability during the view of optic flow stimuli in young (n=17) and old (n=19) people, using stabilometry and kinematic. Results showed that old people showed a greater effort to maintain posture during the view of optic flow stimuli than the young. Elderly seems to use the head stabilization on trunk strategy. Visual stimuli evoke an excitatory input on postural muscles, but the stimulus structure produces different postural effects. Peripheral optic flow stabilizes postural sway, while random and foveal stimuli provoke larger sway variability similar to those evoked in baseline. Postural control uses different mechanisms within each leg to produce the appropriate postural response to interact with extrapersonal environment. Ageing reduce the effortlessness to stabilize posture during optic flow, suggesting a neuronal processing decline associated with difficulty integrating multi-sensory information of self-motion perception and increasing risk of falls.

Implementation of a VLSI amplifier interfaced with biomedical sensors for ultra wide band data transmission

This thesis presents a CMOS Amplifier with High Common Mode rejection designed in UMC 130nm technology. The goal is to achieve a high amplification factor for a wide range of biological signals (with frequencies in the range of 10Hz-1KHz) and to reject the common-mode noise signal. It is here presented a Data Acquisition System, composed of a Delta-Sigma-like Modulator and an antenna, that is the core of a portable low-complexity radio system; the amplifier is designed in order to interface the data acquisition system with a sensor that acquires the electrical signal. The Modulator asynchronously acquires and samples human muscle activity, by sending a Quasi-Digital pattern that encodes the acquired signal. There is only a minor loss of information translating the muscle activity using this pattern, compared to an encoding technique which uses astandard digital signal via Impulse-Radio Ultra-Wide Band (IR-UWB). The biological signals, needed for Electromyographic analysis, have an amplitude of 10-100μV and need to be highly amplified and separated from the overwhelming 50mV common mode noise signal. Various tests of the firmness of the concept are presented, as well the proof that the design works even with different sensors, such as Radiation measurement for Dosimetry studies.

Effect of selective dorsal rhizotomy on gait in children with bilateral spastic paresis: kinematic and EMG-pattern changes

Selective dorsal rhizotomy (SDR) is an effective treatment for reducing spasticity and improving gait in children with spastic cerebral palsy. Data concerning muscle activity changes after SDR treatment are limited.

Endurance training modulates the muscular transcriptome response to acute exercise

We hypothesized that in untrained individuals (n=6) a single bout of ergometer endurance exercise provokes a concerted response of muscle transcripts towards a slow-oxidative muscle phenotype over a 24-h period. We further hypothesized this response during recovery to be attenuated after six weeks of endurance training. We monitored the expression profile of 220 selected transcripts in muscle biopsies before as well as 1, 8, and 24 h after a 30-min near-maximal bout of exercise. The generalized gene response of untrained vastus lateralis muscle peaked after 8 h of recovery (P=0.001). It involved multiple transcripts of oxidative metabolism and glycolysis. Angiogenic and cell regulatory transcripts were transiently reduced after 1 h independent of the training state. In the trained state, the induction of most transcripts 8 h after exercise was less pronounced despite a moderately higher relative exercise intensity, partially because of increased steady-state mRNA concentration, and the level of metabolic and extracellular RNAs was reduced during recovery from exercise. Our data suggest that the general response of the transcriptome for regulatory and metabolic processes is different in the trained state. Thus, the response is specifically modified with repeated bouts of endurance exercise during which muscle adjustments are established.

Anxiety trait modulates psychophysiological reactions, but not habituation processes related to affective auditory stimuli

BACKGROUND: It is well known that there are specific peripheral activation patterns associated with the emotional valence of sounds. However, it is unclear how these effects adapt over time. The personality traits influencing these processes are also not clear. Anxiety disorders influence the autonomic activation related to emotional processing. However, personality anxiety traits have never been studied in the context of affective auditory stimuli. METHODS: Heart rate, skin conductance, zygomatic muscle activity and subjective rating of emotional valence and arousal were recorded in healthy subjects during the presentation of pleasant, unpleasant, and neutral sounds. Recordings were repeated 1 week later to examine possible time-dependent changes related to habituation and sensitization processes. RESULTS AND CONCLUSION: There was not a generalized habituation or sensitization process related to the repeated presentation of affective sounds, but rather, specific adaptation processes for each physiological measure. These observations are consistent with previous studies performed with affective pictures and simple tones. Thus, the measures of skin conductance activity showed the strongest changes over time, including habituation during the first presentation session and sensitization at the end of the second presentation session, whereas the facial electromyographic activity habituated only for the neutral stimuli and the heart rate did not habituate at all. Finally, we showed that the measure of personality trait anxiety influenced the orienting reaction to affective sounds, but not the adaptation processes related to the repeated presentation of these sounds.

Cellular and network mechanisms of rhythm generation in spinal cord circuits

The generation of rhythmic electrical activity is a prominent feature of spinal cord circuits that is used for locomotion and also for circuit refinement during development. The mechanisms involved in rhythm generation in spinal cord networks are not fully understood. It is for example not known whether spinal cord rhythms are driven by pacemaker neurons and if yes, which neurons are involved in this function. We studied the mechanisms involved in rhythm generation in slice cultures from fetal rats that were grown on multielectrode arrays (MEAs). We combined multisite extracellular recordings from the MEA electrodes with intracellular patch clamp recordings from single neurons. We found that spatially restricted oscillations of activity appeared in most of the cultures spontaneously. Such activity was based on intrinsic activity in a percentage of the neurons that could activate the spinal networks through recurrent excitation. The local oscillator networks critically involved NMDA, AMPA and GABA / glycine receptors at subsequent phases of the oscillation cycle. Intrinsic spiking in individual neurons (in the absence of functional synaptic coupling) was based on persistent sodium currents. Intrinsic firing as well as persistent sodium currents were increased by 5-HT through 5-HT2 receptors. Comparing neuronal activity to muscle activity in co-cultures of spinal cord slices with muscle fibers we found that a percentage of the intrinsically spiking neurons were motoneurons. These motoneurons were electrically coupled among each other and they could drive the spinal networks through cholinergic recurrent excitation. These findings open the possibility that during development rhythmic activity in motoneurons is not only involved in circuit refinement downstream at the neuromuscular endplates but also upstream at the level of spinal cord circuits.

Eccentric endurance training in subjects with coronary artery disease: a novel exercise paradigm in cardiac rehabilitation?

This study evaluated the effects of 8 weeks of eccentric endurance training (EET) in male subjects (age range 42-66 years) with coronary artery disease (CAD). EET was compared to concentric endurance training (CET) carried out at the same metabolic exercise intensity, three times per week for half an hour. CET ( n=6) was done on a conventional cycle ergometer and EET ( n=6) on a custom-built motor-driven ergometer. During the first 5 weeks of the training program the metabolic load was progressively increased to 60% of peak oxygen uptake in both groups. At this metabolic load, mechanical work rate achieved was 97 (8) W [mean (SE)] for CET and 338 (34) W for EET, respectively. Leg muscle mass was determined by dual-energy X-ray absorptiometry, quadriceps strength with an isokinetic dynamometer and muscle fibre composition of the vastus lateralis muscle with morphometry. The leg muscle mass increased significantly in both groups by some 3%. Strength parameters of knee extensors improved in EET only. Significant changes of +11 (4.9)%, +15 (3.2)% and +9 (2.5)% were reached for peak isometric torque and peak concentric torques at 60 degrees s(-1) and 120 degrees s(-1), respectively. Fibre size increased significantly by 19% in CET only. In conclusion, the present investigation showed that EET is feasible in middle-aged CAD patients and has functional advantages over CET by increasing muscle strength. Muscle mass increased similarly in both groups whereas muscle structural composition was differently affected by the respective training protocols. Potential limitations of this study are the cautiously chosen conditioning protocol and the restricted number of subjects.

Stair climbing - An insight and comparison between women with and without joint hypermobility: A descriptive study.

Generalized joint hypermobility (GJH) is a frequent entity in rheumatology with higher prevalence among women. It is associated with chronic widespread pain, joint dislocations, arthralgia, fibromyalgia and early osteoarthritis. Stair climbing is an important functional task and can induce symptoms in hypermobile persons. The aim of this study was to compare ground reaction forces (GRF) and muscle activity during stair climbing in women with and without GJH. A cross-sectional study of 67 women with normal mobility and 128 hypermobile women was performed. The hypermobile women were further divided into 56 symptomatic and 47 asymptomatic. GRFs were measured by force plates embedded in a six step staircase, as well as surface electromyography (EMG) of six leg muscles. Parameters derived from GRF and EMG were compared between groups using t-test and ANOVA. For GRF no significant differences were found. EMG showed lower activity for the quadriceps during ascent and lower activity for hamstrings and quadriceps during descent in hypermobile women. For symptomatic hypermobile women these differences were even more accentuated. The differences in EMG may point towards an altered movement pattern during stair climbing, aimed at avoiding high muscle activation. However, differences were small, since stair climbing seems to be not demanding.

Oxygen consumption while standing iwth and unstable shoe design

This study explored the effects of unstable shoe design on oxygen consumption. Methods. Oxygen consumption (VO2) and heart rate (HR) were measured in 16 individuals while barefoot, wearing unstable shoes (Masai Barefoot Technology) and wearing conventional sport shoes while standing and walking on a treadmill and for 5 individuals while walking around a 400 m track. Results. When wearing the MBT shoes, a significant (p < 0.01) increase of 9.3 ± 5.2% in VO2 was measured while standing quietly for 6 min. No differences in VO2 and HR were observed between the MBT shoes or weight-adjusted conventional shoes (to match the weight of the MBT shoes) while walking on a treadmill. However, significant increases (p < 0.01) in VO2 (4.4 ± 8.2%) and HR (3.6 ± 7.3%) were observed for the MBT shoes compared with being barefoot. No significant differences in VO2 and HR were recorded while walking around a 400 m track either with MBT shoes, weight-adjusted conventional shoes or barefoot. Nonetheless, a comparison of the MBT shoes with barefoot revealed a tendency for VO2 to be higher when wearing the MBT shoes (7.1 ± 6.5%, p < 0.1) although HR was not significantly affected. Conclusions. The unstable shoe design predominantly effects oxygen consumption while standing, most likely due to increased muscle activity of the lower extremities.

First evidence for differential and sequential efferent effects of stimulus relevance and goal conduciveness appraisal.

In the context of a memory task, participants were presented with pictures displaying biological and cultural threat stimuli or neutral stimuli (stimulus relevance manipulation) with superimposed symbols signaling monetary gains or losses (goal conduciveness manipulation). Results for heart rate and facial electromyogram show differential efferent effects of the respective appraisal outcomes and provide first evidence for sequential processing, as postulated by Scherer's component process model of emotion. Specifically, as predicted, muscle activity over the brow and cheek regions marking the process of relevance appraisal occurred significantly earlier than facial muscle activity markers of goal conduciveness appraisal. Heart rate, in contrast, was influenced by the stimulus relevance manipulation only.

The Sensitivity of Physiological Measures to Phobic and Nonphobic Fear Intensity

We investigated whether amygdala activation, autonomic responses, respiratory responses, and facial muscle activity (measured over the brow and cheek [fear grin] regions) are all sensitive to phobic versus nonphobic fear and, more importantly, whether effects in these variables vary as a function of both phobic and nonphobic fear intensity. Spider-phobic and comparably low spider-fearful control participants imagined encountering different animals and rated their subjective fear while their central and peripheral nervous system activity was measured. All measures included in our study were sensitive to variations in subjective fear, but were related to different ranges and positions on the subjective fear level continuum. Left amygdala activation, heart rate, and facial muscle activity over the cheek region captured fear intensity variations even within narrowly described regions on the fear level continuum (here within extremely low levels of fear and within considerable phobic fear). Skin conductance and facial muscle activity over the brow region did not capture fear intensity variations within low levels of fear: skin conductance mirrored only extreme levels of fear, and activity over the brow region distinguished phobic from nonphobic fear but also low-to-moderate and high phobic fear. Finally, respiratory measures distinguished phobic from nonphobic fear with no further differentiation within phobic and nonphobic fear. We conclude that a careful consideration of the measures to be used in an investigation and the population to be examined can be critical in order to obtain significant results.

Proximal Femoral Osteotomies with the Paediatric Hip Plate (LCP): Valgus osteotomy.

OBJECTIVE Proximal femoral osteotomy with stable fixation and sufficient correction. Low complication rates due to exact preoperative planning. INDICATIONS Congenital or traumatic femoral neck pseudarthrosis. Coxa vara. CONTRAINDICATIONS None. In severe deformities, a single femoral osteotomy may not solve the problem; thus, additional correction, e.g., a pelvic osteotomy, is required. SURGICAL TECHNIQUE Correct planning of the correction angle. Lateral approach. Subperiosteal detachment of vastus lateralis muscle. Place guide wire on the femoral neck to judge anteversion. Insert positioning wire 5 mm distal to trochanteric physis. Insert 2.8 mm Kirschner wire in the femoral neck. Osteotomy of the femur after marking the rotation by Kirschner wires or oscillating saw. Slide LC plate over Kirschner wires. Replace Kirschner wires with screws. Reduction of the femoral shaft to the plate with bone forceps. Definitive fixation of the plate to the femoral shaft by cortex or locking screws. Readaptation of vastus lateralis muscle over the plate. POSTOPERATIVE MANAGEMENT Partial weightbearing for 4-6 weeks depending on the age of the patient without any external fixation (e. g. cast) is possible. RESULTS Recent studies support the authors' findings of sufficient correction and stable fixation after proximal femoral osteotomy with the LCP pediatric hip plate. Low complication rates and stable fixation.