ВЛИЯНИЕ ФАКТОРОВ «ВЕРТИКАЛЬНОСТЬ», «УСТОЙЧИВОСТЬ» И «ОПОРА ТЕЛА» НА ФЕНОМЕН КОНШТАММА В ДЕЛЬТОВИДНЫХ МЫШЦАХ ЧЕЛОВЕКА

Postactivation effect (PAE, postactivation phenomenon) is a specific type of involuntary muscle tone (tonic automatism) which is generated in the “tonogenic” structures of the brain, presumably without the “sensory copy” and “motor command” mechanisms. In this regard, the electromyogram (EMG) signal of PAE may have a simpler temporal signal structure compared to PAE-inducing voluntary activity. The purpose of this work is to characterize the temporal structure and complexity of surface EMG (sEMG) of the human deltoid and biceps brachii muscles using fractal (D) and correlation dimensions (Dc). It was found that in deltoid muscles the value of D was 1.78–1.81 both during PAE and voluntary effort (p 0.05). Dc (approximately 4.0–4.2) also did not differ between PAE and voluntary effort, although the average frequency of the sEMG spectrum during PAE was 15–16 Hz (p 0.05) higher compared to voluntary effort. In biceps brachii muscles, the D value was 1.8 during PAE and 1.62 during voluntary effort (p 0.05). Dc values did not differ between PAE and voluntary contraction (4–4.8). Thus, despite the supposed difference in the central organization of PAE and voluntary effort, the temporal structure of their sEMG did not differ, indicating that isometric voluntary effort and involuntary tone in the form of PAE share a common principle of sEMG signal generation. At the same time, the differences in the frequency of the sEMG spectrum indicate that the organization of sEMG signal during PAE is specific on the level of the motoneuron pool.

Facilitation of motor evoked potentials by postcontraction response (Kohnstamm phenomenon)

Postactivation Effect in the Deltoid Muscle of Healthy Young Subjects after a Short-Term “Dry” Immersion

Neuromodulation plays a central role in human movement control. An imbalance of neurotransmitters, especially dopamine and serotonin, can be associated with various neurological disorders causing tremors or spasms. Specifically, serotonin was shown to scale motoneuron excitability following intense muscle contractions, affecting short-latency reflexes. Likely, it may also influence motoneuron modulation in prolonged contractions, although this lacks experimental evidence. An intriguing test case for this hypothesis is presented by the Kohnstamm phenomenon, where sustained muscle contractions lead to prolonged amplified EMG activity and involuntary motions, aligning with the timescale of serotonergic amplification. The suspected serotonin influence on this effect was tested in a placebo-controlled human user study with 14 participants, where half were administered the serotonin antagonist Cyproheptadine and the other half a placebo. Comparing EMG and force responses after inducing the Kohnstamm phenomenon in the deltoid muscles revealed statistically significant faster EMG decay with the serotonin antagonist, while decay remained consistent in the placebo group compared to the response of the same participant group without medication. The force measurements showed the same trend, although no significance. This provides new data-based evidence that serotonin contributes to long-term motoneuron modulation, extending previous findings about the dedicated role and influence of this neurotransmitter. Additionally, the work suggests the phenomenon as an interesting test case to investigate the dedicated involvement of different neurocontrol mechanisms such as Persistent Inward Currents.

Context: Stature or height in upright position has an important role in medico-legal practice. In many tragic events or in crime scenes, direct identification of the victims is difficult because only mutilated, decomposed and amputed body fragments may be found. In such situations estimation of stature helps in establishing the biological profile of the victims through examination of the dismembered body parts remain.This study was aimed to investigate the correlation between stature and foot lengths, to derive regression equations for stature estimation from foot lengths and to make comparison with previous studies on other populations. Materials & Methods: This cross-sectional study was carried out at the Anatomy Department of Sir Salimullah Medical College, Dhaka, Bangladesh from January 2017 to December 2017 on 50 male medical and dental students aged between 21 and 26 years. Full foot length (FFL) and truncated foot length (TFL) were measured by MB ruler software. Relationships between stature and foot lengths were obtained by Pearson’s correlation coefficient test. Results: Both FFL and TFL showed significant positive correlation with stature (r = 0.709 and 0.618 respectively). The linear regression equation for stature estimation derived from FFL and TFL were 60.954 + 4.571FFL and 81.687 + 4.915TFL respectively. The linear regression equations derived from FFL have larger correlation coefficient (R), coefficient of determination (R2), adjusted coefficient of determination (adj R2) and smaller standard error of estimation (SEE) than those derived from TFL. Bangladesh Journal of Anatomy January 2019, Vol. 17, No. 1, pp. 5-9

While exoskeleton technology is becoming more and more common for gait rehabilitation in children with neurological disorders, evaluation of gait performance still faces challenges and concerns. The reasoning behind evaluating the spinal locomotor output is that, while exoskeleton's guidance forces create the desired walking kinematics, they also affect sensorimotor interactions, which may lead to an abnormal spatiotemporal integration of activity in particular spinal segments and the risk of abnormalities in gait recovery. Therefore, traditional indicators based on kinematic or kinetic characteristics for optimizing exoskeleton controllers for gait rehabilitation may be supplemented by performance measures associated with the neural control mechanisms. The purpose of this study on a sample of children was to determine the basic features of lower limb muscle activity and to implement a method for assessing the neuromechanics of spinal locomotor output during exoskeleton-assisted gait. To this end, we assessed the effects of a robotic exoskeleton (ExoAtlet Bambini) on gait performance, by recording electromyographic activity of leg muscles and analyzing the corresponding spinal motor pool output. A slower walking setting (about 0.2 m/s) was chosen on the exoskeleton. The results showed that, even with slower walking, the level of muscle activation was roughly comparable during exoskeleton-assisted gait and normal walking. This suggests that, despite full assistance for leg movements, the child's locomotor controllers can interpret step-related afferent information promoting essential activity in leg muscles. This is most likely explained by the active nature of stepping in the exoskeleton (the child was not fully relaxed, experienced full foot loading and needed to maintain the upper trunk posture). In terms of the general muscle activity patterns, we identified notable variations for the proximal leg muscles, coactivation of the lumbar and sacral motor pools, and weak propulsion from the distal extensors at push-off. These changes led to the lack of characteristic lumbosacral oscillations of the center of motoneuron activity, normally associated with the pendulum mechanism of bipedal walking. This work shows promise as a useful technique for analyzing exoskeleton performance to help children develop their natural gait pattern and to guide system optimization in the future for inclusion into clinical care.

To compare the safety of haemophilus influenzae type b (Hib) vaccine vaccination on vastus lateralis muscle and deltoid muscle of infant. A total of 408 3-4 months old infants were divided into vastus lateralis muscle group and deltoid muscle group in Beijing, 2014. They were divided into the vastus lateralis muscle group (204) and deltoid muscle group (204) by extracting random number. Each observation object was given 3 doses of Hib vaccine according to the program. Collected systemic and local reactions after vaccination and calculated the incidence of adverse reactions. A total of 61 infants were quitted during the study, 1 132 doses were observed. The total reactions incidence of Vastus lateralis muscle group and Deltoid muscle group were 33.0% (186/564) and 27.6% (157/568) with no statistical differences (χ² = 3.818, P = 0.059). The two groups incidence at the same day of vaccination (day 0) which the highest were 23.2% (131/564) and 20.6% (117/568), then declined with time (linear trend test vastus lateralis muscle group χ² = 36.600, P < 0.001,deltoid muscle group χ² = 29.947, P < 0.001), day 1 were 20.4% (115/564) and 17.6% (100/568), day 2 were 16.0% (90/564) and 13.4% (76/568), day 3 were 10.3% (58/564) and 10.6% (60/568), day 4-7 were 11.2% (63/564) and 11.3% (64/568). No serious adverse events (SAE) were reported during the study. The local reactions incidence of two groups were 7.1% (40/564) and 7.7% (44/568)with no statistical differences (χ² = 0.176, P = 0.675). The systemic reactions incidence of two groups were 25.9% (146/564) and 20.6% (117/568) with obvious statistical differences (χ² = 4.437, P = 0.035). The fever incidence of vastus lateralis muscle group (11.5% (65/564)) was higher than Deltoid muscle group (4.4% (25/568)) with obvious statistical differences (χ² = 4.868, P = 0.027). The 1st dose incidence of fever and abnormal crying of vastus lateralis muscle group (fever 11.3% (23/204), abnormal crying 19.1% (39/204)) was higher than deltoid muscle group (fever 4.4% (9/204), abnormal crying 11.8% (24/204)) and the 2nd dose of diarrhea of deltoid muscle group (11.6% (22/190)) was higher than vastus lateralis muscle group (5.9% (11/187)) with obvious statistical differences (fever χ² = 15.288, P < 0.001, abnormal crying χ² = 4.224, P = 0.040, diarrhea χ² = 3.829, P = 0.046). Both vastus lateralis muscle group and deltoid muscle group had lower incidence of adverse reactions after vaccination. No serious adverse events were associated with vaccination. Vastus lateralis muscle vaccination as well as deltoid muscle vaccination demonstrated safe.

Objective To analyze characteristic changes of shoulder muscles by investigating surface electromyographic regularity changes before and after the treatment of Frozen shoulders. Methods 7 cases of frozen shoulders were selected, surface electromyography (sEMG) before and after treatment were recorded by AMT-8 EMG recorder. The collected data was processed using MATLAB software integrated EMG (IEMG) value were obtained. Then the IEMG data were statistically analyzed using Stata11.0 software and compared. Results ①The differences of abduction deltoid and infraspinatus muscle IEMG values before and after treatment were statistically significant (P ＜0.05), while IEMG values changes of biceps, triceps, pectoralis major, latissimus dorsi and trapezius before and after treatment were not statistically significant (P＞0.05); changes of adduction IEMG values of all muscles were not statistically significant (P＞0.05). ②Changes of flexion IEMG values of biceps before and after treatment were statistically significant (P＜0.05), while IEMG values changes of pectoralis major, infraspinatus muscle, latissimus dorsi, trapezius, deltoid, triceps before and after treatment were not statistically significant (P＞0.05). Changes of extension IEMG values of triceps before and after treatment were statistically significant (P＜0.05), while those of pectoralis major, infraspinatus muscle, latissimus dorsi, trapezius, deltoid and biceps were not statistically significant (P＞0.05). ③IEMG values of all the muscles during external rotation, internal rotation before and after treatment IEMG were not significantly different. Conclusion ①After treatment, the outreach functions of infraspinatus and deltoid muscles were improved, while adduction functions of all muscles were not improved. ②Flexion function of biceps was improved significantly after treatment as well as extension function of triceps.③Extemal rotation, internal rotation functions of all muscles were not improved significantly. Key words: Frozen shoulder, Three-dimensional motion; Surface electromyography; Integrated EMG analysis; Functional evaluation

Balance disorders are a risk factor for falls in the elderly population. Balance control involving the complex interaction among nervous, muscular, and sensory systems should be maintained to keep an upright posture and prevent falls. Vestibular sensation is one of the main senses essential for postural control. Noisy galvanic vestibular stimulation (nGVS) is a noninvasive stimulation method for vestibular organs. Recently, it has received increasing attention for the treatment of balance disorders. However, the effect of balance disorders on stimulus effect during the implementation of nGVS remains unknown. Therefore, this study aimed to determine the effects of different floor surface and visual conditions on the stimulus effects of the nGVS intervention. In this study, two experiments were conducted with 24 participants (12 each for Experiments 1 and 2). In Experiment 1, nGVS (0.4 mA; 0.1–640 Hz) was performed in the open-eyes standing position on a solid surface (nGVS condition) and in the closed-eye standing position on a foam rubber (nGVS + foam rubber condition). In Experiment 2, sham stimulation was performed under the same conditions as in Experiment 1, except for nGVS. Center of pressure (COP) sway was measured in all participants with them standing with open eyes at Pre and Post-1 (immediately after the intervention) and Post-2 (10 min after the measurement of post-1). In Experiment 1, under the nGVS condition, COP sway was significantly reduced in Post-1 and Post-2 compared with Pre. However, no significant difference was observed among Pre, Post-1, and Post-2 under the nGVS + foam rubber condition. Furthermore, the intervention effect was significantly greater in the nGVS condition than in the nGVS + foam rubber condition. In contrast, in Experiment 2, the COP sway did not significantly differ among Pre, Post-1, and Post-2 under either condition. Based on the results of this study, nGVS was found to be effective with open-eyes standing on a solid surface.

We report a case of a progressive bilateral C5 palsy (C5P) following multilevel posterior cervical decompression and fusion surgery that was successfully treated with conservative management. A 58-year-old female patient with ossification of the posterior longitudinal ligament and resulting spinal canal stenosis underwent surgery in August 2015. Weakness in her both deltoid and biceps muscles was immediately detected after surgery and gradually deteriorated to severe paresis in the following 2 days. Postoperative magnetic resonance imaging showed sufficient decompression of the spinal cord with posterior shifting. However, residual neuroforaminal bilateral stenosis at levels C4/5 and C5/6 was found on postoperative computed tomography. After discussion of the therapeutic options, we decided to start conservative management including physical therapy and to follow the patient closely including clinical and neurophysiological examinations for the next 12 months. After 3 months, improvement of bilateral paresis was already evident. Muscle strength in the right biceps and the right deltoid muscles recovered completely within a year, but Grade 4 muscle weakness remained in the left deltoid and biceps muscles. Repetitive electromyography also showed continuous improvement of the interference patterns of the deltoid and biceps muscles. Although a standard management protocol for the treatment of postoperative C5P has not yet been established, a conservative therapy may be warranted even for severe and bilateral C5P.

Small drops adhering to a ceiling under a gravitational field are found in many industrial and natural situations. This work investigates a novel scheme to rapidly remove these pendent drops from a solid surface by vibrating the drop. In the experiments, a water drop pendent from a solid surface is vibrated at a fixed frequency while increasing the vibration amplitude. Upon repeating the experiments using different frequencies, it is revealed that there exist resonant frequencies at which the minimum vibration amplitudes inducing a fall-off of the pendent drops are remarkably less than the detaching amplitudes at neighboring frequencies. These frequencies are supposed to correspond to the resonant frequencies of different drop oscillation modes. They are compared with the resonant frequencies predicted by relatively simple analyses, and the factors causing discrepancy between them are discussed.

A free dense body in a vibrating cavity with an incompressible fluid executes vibrations under the action of an oscillating force. The hydrodynamic interaction of the vibrating body with the fluid creates a lift force, which depends strongly on the character of the vibration. In the presence of the translational vibrations of the cavity, motion is induced in the fluid by body vibrations (in the absence of the body or when the densities of the body and fluid are equal to each other, the fluid is at rest in the cavity reference frame). High-frequency vibrations have traditionally been considered. In this case, the viscous boundary layer near the solid surface is negligibly narrow and viscosity can be disregarded when describing the vibrational motion of the fluid. The mean force appears due to the breaking of the symmetry of the pulsation velocity field and pressure field on the body surface. This scenario is realized when the body vibrates at a certain distance from the wall of the cavity (it is attracted to the wall) or near another body [1‐3]. This interaction decreases rapidly when the distance increases. Another mechanism is manifested in the case of combined, translational‐rotational vibrations of the cavity, such as pendulum vibrations. Here, the rotational vibration component induces vibrations of the fluid with respect to the cavity that are not associated with the presence of the body, and the intense translational component generates synchronous vibrations of the body. In this case, the resulting lift force is manifested over the entire cavity volume and is so strong that it can ensure the flotation of the heavy body in the gravitational field [4, 5]. The above problems refer to the high frequency limiting case. When the viscosity of the fluid is substantial, i.e., when the size of the body or the distance between bodies is comparable with the thickness of Stokes layers, the vibrational interaction between bodies becomes complicated and the direction of mean forces is often opposite, which is demonstrated in both physical experiments [5] and numerical calculations [6]. In this work, we carry out an experimental study on the lift force acting on the dense spherical body in the viscid incompressible fluid near the wall of the cavity that executes longitudinal vibrations. Measurement of the vibrational lift force acting on a body is based on comparisons with the gravitational force: quasi-stationary suspended states are studied when the lift force is in balance with the weight of the body, more precisely, with its component perpendicular to the boundary. A procedure for reducing the effective action of the gravitational force is used [5]; i.e., the interaction of the body with the lateral wall of the cavity, which is inclined at a small angle α to the vertical line, is studied. The body vibrates along this wall, being continuously supported in the plane to which the wall is perpendicular. In the equilibrium suspended state, when the body does not touch the lateral wall, the vibrational force perpendicular to this wall is in balance with the tangent component of the gravitational force P n . This component can vary over a wide range due to variation in the angle α . Using small angles, one can measure even weak vibrational forces under normal gravitational conditions.

We previously reported in C2C12 myotubes that a Rhaponticum carthamoides root extract (RCE) was able to significantly stimulate protein synthesis and induce an activation of the Akt/mTOR signalling pathway (induction of Akt and S6K1 phospohrylations), that a Rhodiola rosea root extract (RRE) had also the capacity to induce protein synthesis and to inhibit myostatin gene expression and that the combination of both exhibited inhibition of atrogin gene expression (unpublished). Therefore, we aimed to investigate the effects of RCE or RRE alone or combinations of both on acute muscle protein synthesis stimulation and on performance gain following a 4-week resistance training program in adult rats. Acutely, rats were trained on a ladder making 3 repetitions of 10 climbs with a load that successively reached 0%, 50% and 75% of their body mass and were fed (oral gavage) just after training with either placebo, whey protein (910 mg/kg bw) as a positive control, RRE (43 mg/kg bw), RCE (43 mg/kg) and different doses of a 50:50 combination of both (87, 43, 22 or 9 mg/kg bw). RCE alone but not RRE was able to significantly stimulate protein synthesis as measured by western blot quantitative analysis of puromycin incorporation in the flexor digitorum profondus (FDP) and in comparison to placebo (200% versus 100% for RCE and placebo group respectively). Any doses of the combination was significantly superior to RRE alone (300% versus 150%) or RCE alone (300% versus 200%) and also significantly superior to whey proteins (300% versus 150%). The same results were obtained in the biceps and deltoid muscles. In the second part of the study rats followed a 4-week progressive resistance training program while consuming RRE alone (22 mg/kg), RCE alone (22 mg/kg) and different ratio and doses of the combination (50:50 ratio: 43, 22 or 9 mg/kg bw; 83 RCE:17 RRE ratio: 26 mg/kg; 76 RCE:24 RRE ratio: 28 mg/kg; 70 RCE:30 RRE ratio: 15 mg/kg. Training sessions (19) consisted in one set of 10 repetitions with 2 minutes rest between trials and 5 minutes between each set, were held five times a week with initial load fixed at 50% of the rat body weight and increased progressively until 200% after 4 weeks. Maximal repetition was determined as the maximum weight carried up the exercise ladder by the rats in one climb and performance gain was calculated as delta power (post versus pre resistance training). As shown in Figure 1, RCE alone but not RRE was able to significantly increase performance gain in comparison to placebo after 4 weeks of resistance training (0.66±0.08 versus 0.39±0.08 W respectively, + 65%, p<0.05). A synergistic effect on performance gain was detected for the 50:50 combination but interestingly, the combination ratio 70:30 warranted the best improvement of performance gain with the lower daily dosage (15 mg/kg bw) in comparison to placebo (0.62±0.08 versus 0.39±0.08 W respectively, + 59%, p<0.05). These results clearly demonstrated synergy of the combination of extracts on protein synthesis stimulation in the FDP, deltoid and biceps muscles following acute resistance exercise and an improvement of performance gain following a 4-week resistance training program. Those effects are currently investigated in recreationally active men and histological analysis of muscle fibers are under investigations in rats to understand what could drive the effect on performance.

Objective To observe the origin of the nerves innervating the subscapularis muscle and its anagonistic muscles at brachial plexus root or trunk level, and the blood supply of the subscapularis muscle in order to clarify the mechanism of subscapularis muscle contracture in obstetric brachial plexus palsy (OBPP). Methods 32 sides of adult human cadavers were used. The innervating nerve of the subscapularis muscle and its antagonistic muscles (the infraspinatus muscle, the teres minor muscle, the deltoid muscle and the supraspinatus muscle) were dissected retrogradely to trace its origin at the root and trunk level of the brachial plexus. The nerve fiber external diameter in the corresponding root and/or trunk was measured and the constituent ratios in the root and/or trunk of the brachial plexus were calculated. The nutrient arteries of the subscapularis muscle were observed to compare the number and distribution of the arteries to the upper parts of the subscapularis muscle and the lower parts. Results The nerve fibers innervating the subscapularis muscle mainly originated from the upper and middle trunk. The percentage in the upper trunk was (81.61 ± 6.85)%, while that in the middle trunk was (18.39 ± 6.85)%. The nerve fibers of its antagonistic muscles only originated from the upper trunk. Not only the number but also the diameter of the arteries entering the upper parts of the muscle was larger than those entering the lower parts. Conclusions The difference in the nerve fiber origin between the subscapularis muscle and its antagonistic muscles and the characteristics of the blood supply of the subscapularis muscle were the major causes of subscapularis muscle contracture in obstetric brachial plexus palsy.

Numerical simulation of two-phase droplets on a curved surface using Surface Evolver