Movements Of Hind Legs Research Articles

Short Communication - Possible aetiology of the posterior presentation in Perosomus elumbis

The aetiology of foetal presentation in cattle is still unresolved. The hind legs are the main source of propulsive movement in cattle, which provides changes in foetal presentation. The assumption is that in the absence of hind leg movements of the foetus, as in the case of the congenital malformation, Perosomus elumbis, the incidence of the anterior and posterior presentation will be the same. The Scopus database, the world wide web (www), and the list of article references were searched using the keyword, Perosomus elumbis. Manuscripts with data about the foetal presentation were included and 21 cases in 16 articles were identified. There were 11 cases of anterior presentation and 10 of posterior presentation. The Chi-square test didn't show a statistically significant difference between the incidence of anterior and posterior presentation. This finding supports the assumption that the posterior presentation is the result of the random occupying of the intrauterine space with the same probability of anterior and posterior presentation. To confirm or exclude at random the occupant of the intrauterine space with the same probability for anterior and posterior presentation as a general mechanism for posterior presentation in cattle foetuses, it is necessary to determine the incidence of foetal presentation at birth in various veterinary entities accompanied by an increased incidence of posterior presentation. The aim of the paper was to investigate the incidence of posterior and anterior presentation in Perosomus elumbis.

Jumping in lantern bugs (Hemiptera, Fulgoridae).

ABSTRACTLantern bugs are amongst the largest of the jumping hemipteran bugs, with body lengths reaching 44 mm and masses reaching 0.7 g. They are up to 600 times heavier than smaller hemipterans that jump powerfully using catapult mechanisms to store energy. Does a similar mechanism also propel jumping in these much larger insects? The jumping performance of two species of lantern bugs (Hemiptera, Auchenorrhyncha, family Fulgoridae) from India and Malaysia was therefore analysed from high-speed videos. The kinematics showed that jumps were propelled by rapid and synchronous movements of both hind legs, with their trochantera moving first. The hind legs were 20–40% longer than the front legs, which was attributable to longer tibiae. It took 5–6 ms to accelerate to take-off velocities reaching 4.65 m s−1 in the best jumps by female Kalidasa lanata. During these jumps, adults experienced an acceleration of 77 g, required an energy expenditure of 4800 μJ and a power output of 900 mW, and exerted a force of 400 mN. The required power output of the thoracic jumping muscles was 21,000 W kg−1, 40 times greater than the maximum active contractile limit of muscle. Such a jumping performance therefore required a power amplification mechanism with energy storage in advance of the movement, as in their smaller relatives. These large lantern bugs are near isometrically scaled-up versions of their smaller relatives, still achieve comparable, if not higher, take-off velocities, and outperform other large jumping insects such as grasshoppers.

Observation and analysis of diving beetle movements while swimming

The fast swimming speed, flexible cornering, and high propulsion efficiency of diving beetles are primarily achieved by their two powerful hind legs. Unlike other aquatic organisms, such as turtle, jellyfish, fish and frog et al., the diving beetle could complete retreating motion without turning around, and the turning radius is small for this kind of propulsion mode. However, most bionic vehicles have not contained these advantages, the study about this propulsion method is useful for the design of bionic robots. In this paper, the swimming videos of the diving beetle, including forwarding, turning and retreating, were captured by two synchronized high-speed cameras, and were analyzed via SIMI Motion. The analysis results revealed that the swimming speed initially increased quickly to a maximum at 60% of the power stroke, and then decreased. During the power stroke, the diving beetle stretched its tibias and tarsi, the bristles on both sides of which were shaped like paddles, to maximize the cross-sectional areas against the water to achieve the maximum thrust. During the recovery stroke, the diving beetle rotated its tarsi and folded the bristles to minimize the cross-sectional areas to reduce the drag force. For one turning motion (turn right about 90 degrees), it takes only one motion cycle for the diving beetle to complete it. During the retreating motion, the average acceleration was close to 9.8 m/s2 in the first 25 ms. Finally, based on the diving beetle's hind-leg movement pattern, a kinematic model was constructed, and according to this model and the motion data of the joint angles, the motion trajectories of the hind legs were obtained by using MATLAB. Since the advantages of this propulsion method, it may become a new bionic propulsion method, and the motion data and kinematic model of the hind legs will be helpful in the design of bionic underwater unmanned vehicles.

Detection of cow hind-leg activity during milking by using a 3-dimensional accelerometer attached to the milking cluster

Hind-leg activity in dairy cows during milking is considered an indicator of a stressful situation or discomfort. Automatic detection of cow hind-leg activity during milking could be used to monitor deficiencies at the cow, milking machine, or human level. We assumed that the milking cluster follows cow hind-leg movements during milking. Therefore, the aim of our study was to estimate the ability of a 3-dimensional (3D) accelerometer attached to the claw's hook of the milking cluster to indirectly measure cow hind-leg activity during milking. The behavior of 45 dairy cows during 1 morning and 1 evening milking in a 2 × 3 auto tandem milking parlor was monitored by using direct visual observations and a 3D accelerometer attached directly to the hook of each milking claw. We recorded when hind-leg foot-lifting or stepping (undifferentiated) and kicking behaviors occurred. Detected activities were obtained after applying a standard deviation filter (over a sliding window of 1 s) on the x (left/right lateral) acceleration axis only. We set the detection threshold at 0.13 g (i.e., 1.27 m·s−2), based on the visual evaluation of 10 “reference” graphs (from 5 randomly chosen cows). Periods of activity were created for each observed or detected activity (and for consecutive activities that were less than 3 s apart) to take into account the milking cluster's rocking motion resulting from a single movement. Observed and detected periods of activity were considered matching when they occurred simultaneously (with a 2-s delay acceptance in the visual observations). In total, 472 periods of hind-leg activity were observed. The detection of hind-leg activity by using a 3D accelerometer attached to the milking cluster was found to have 69% sensitivity, 99% specificity, 75% positive predictive value, 98% negative predictive value, and an overall accuracy of 97%. On average, cows were observed being active 0.94 times per minute and being detected active 0.86 times per minute. The observed and detected periods of activity were found to be correlated (r = 0.657). Therefore, the use of a 3D accelerometer attached to the milking cluster seems promising for reliably estimating cow hind-leg activity during milking. Nevertheless, further investigations are necessary to clarify whether other factors can cause variations in milking cluster movements, regardless of cow hind-leg activity, and to generalize our method to better identify deficiencies in cow–machine–human interactions.

The relationship between water buffalo cow temperament and milk yield and quality traits

The aims of this study were to assess the relationship between reactivity during milking and daily distances traveled by lactating water buffalo cows and to assess the association of these behavioral traits with milk yield and quality traits. Reactivity during milking was measured as a 4-point milking reactivity score (MRS, N=114 cows) where 1=stands quietly, 2=slight hind leg movements, 3=vigorous hind leg movements, and 4=continual vigorous hind leg movements or the stockperson ties the animal. Cows were classified according to their consistency for MRS within each month as 1) inconsistent (same MRS in fewer than 50% of observations), 2) moderately consistent (same MRS in 50–74.9% of observations), or 3) consistent (same MRS in at least 75% of observations). GPS collars were used to calculate the average daily distance traveled (DDT) by each cow (N=36). Milk yield and quality traits (fat, protein and lactose content, as well as somatic cell count) were measured once a month during the three months of the study. Results showed that DDT was not related to MRS (F=0.78, P=0.47). Furthermore, MRS was negatively associated with milk yield (F2,66=3.75; P=0.02), fat content (F2,71=3.34; P=0.04), and linear somatic cell score (LSCS) (F2,69=4.06; P=0.02). Reactive cows (MRS 3+4) had lower daily milk yield than MRS 1 cows, with lower fat content and higher LSCL than MRS 2 cows. On the other hand, DDT was not associated with milk yield or any quality traits (P>0.05) other than LSCS (R2=0.60; P<0.05). Since MRS and DDT were not correlated, we conclude that these traits reflect distinct aspects of water buffalo cows’ temperament. Milk yield and quality were not related to DDT, indicating that only MRS was associated with the productive traits in lactating water buffalo cows.

Design, Implementation and Analysis of 3D Printed Grasshopper Robot for Jumping Mechanism

This scientific paper consists of the analysis of the grasshopper jumping mechanism through literature studies, manufacturing, analysis and experimentation to enhance the knowledge to the manufacturing and analyzing of the artificially developed grasshopper-like robots. The first step involved the understanding of the actual grasshopper mechanisms which was carried out by the dissection of actual grasshopper bodies to analyze the hind leg movements, actuating muscles and structured sizes of the involved organs. The next step involved the development structural of the prototype consisted of design of the grasshopper jumping robot and the durability of the structure was checked at the critical locations. The results indicated that the strains produced in the tibia (immediately before and immediately after the jump) and femur of the designed structure was 2.5.10-5, 3.2.10-5 and 634.10-5 respectively. Whereas, the maximum allowable strain of the material during elastic deformation is 660.10-5, so the design of the structure could satisfy the strength requirements. The structural strength of the tibia and femur with the vertical printing were also in line with the stress requirements. Fabrication and jumping test was carried out which indicated 5 times higher jumps for the designed and fabricated grasshopper like jumping robot. This result is very helpful in robotic industry for the smooth movements of the robots for carrying out the intended function on rough terrains.

MP28-13 URETHRAL AND DETRUSOR DYSFUNCTION ARE DETERMINED BY THE SEVERITY OF A CONTUSION-SCI IN FEMALE RATS

You have accessJournal of UrologyBladder & Urethra: Anatomy, Physiology & Pharmacology I1 Apr 2016MP28-13 URETHRAL AND DETRUSOR DYSFUNCTION ARE DETERMINED BY THE SEVERITY OF A CONTUSION-SCI IN FEMALE RATS Timothy Boone, Carolina Rivera, and Alvaro Munoz Timothy BooneTimothy Boone More articles by this author , Carolina RiveraCarolina Rivera More articles by this author , and Alvaro MunozAlvaro Munoz More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.1063AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Rodent models for the study of neurogenic bladder dysfunction (NBD) after spinal cord injury (SCI) are difficult to standardize, mainly due to the reproducibility of partial cord transections, or the severity of a complete transection. The purpose of this study was to characterize the degree of NBD associated with a highly reproducible, contusion-induced, SCI in female rats METHODS We used an infinite horizon impactor to create a contusion SCI with a targeted magnitude of either 100 (102+/-0.75; 100kDy group) or 200 (204+/-1.5; 200kDy group) kDynes at the Th8/Th9 region of SD rats. Rats were video recorded to evaluate locomotion with the BBB scale that varies from 0 (no hind-leg movement) to 21 (normal function). After 4 weeks, cystometry (CMG) was performed via a suprapubic catheter in under urethane anesthesia. SCI severity was assessed by determining the presence of microglia, and MAP-2 expression. Data were analyzed with unpaired t-tests. Values represent mean+/-SEM and p<0.05 was significantly different RESULTS The BBB score at 3 days after SCI was 9.2+/-2.9 and 2.0+/-0.6, while at 4 weeks was 19.7+/-0.6 and 12.0+/-4.5 in the 100kDy and 200kDy groups, respectively. Microglia infiltrates the injury zone without affecting gray matter in the 100kDy group. Major tissue damage was observed in the other group. During CMG we saw increased intercontractile intervals in the 100kDy group, while 200kDy showed clear detrusor-sphincter dyssynergia with irregular voiding intervals and non-voiding contractions (NVC). We found a significantly high frequency of NVC in both SCI groups (23.4+/-6.9 in 100kDy, and 30.0+/-7.8 NVC/h in 200kDy). The duration of intraluminal pressure high frequency oscillations was increased (2.1+/-0.2s in intact, 4.9+/-0.7s in 100kDy, and 6.0+/-2.1s in the 200kDy rats). Micturition volume was significantly reduced in 200kDy SCI group (0.37+/-0.05ml in intact, 0.52+/-0.11ml in 100kDy, and 0.09+/-0.02ml in the 200kDy rats). The flow rate was significantly impaired in the 200kDy group (0.18+/-0.04ml/s in intact, 0.11+/-0.03ml/s in 100kDy, and 0.02+/-0.01ml/s in the 200kDy rats) CONCLUSIONS Our results suggest that a computer-controlled contusion SCI creates a reproducible urethral and bladder dysfunction that is proportional to the applied force. This NBD model simulates the human condition where traumatic SCI are more frequent, and results suggest that even minor changes in the microenvironment of the SCI region can affect bladder function © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e376 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Timothy Boone More articles by this author Carolina Rivera More articles by this author Alvaro Munoz More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Leg mechanics contribute to establishing swing phase trajectories during memory-guided stepping movements in walking cats: a computational analysis.

When quadrupeds stop walking after stepping over a barrier with their forelegs, the memory of barrier height and location is retained for many minutes. This memory is subsequently used to guide hind leg movements over the barrier when walking is resumed. The upslope of the initial trajectory of hind leg paw movements is strongly dependent on the initial location of the paw relative to the barrier. In this study, we have attempted to determine whether mechanical factors contribute significantly in establishing the slope of the paw trajectories by creating a four-link biomechanical model of a cat hind leg and driving this model with a variety of joint-torque profiles, including average torques for a range of initial paw positions relative to the barrier. Torque profiles for individual steps were determined by an inverse dynamic analysis of leg movements in three normal cats. Our study demonstrates that limb mechanics can contribute to establishing the dependency of trajectory slope on the initial position of the paw relative to the barrier. However, an additional contribution of neuronal motor commands was indicated by the fact that the simulated slopes of paw trajectories were significantly less than the observed slopes. A neuronal contribution to the modification of paw trajectories was also revealed by our observations that both the magnitudes of knee flexor muscle EMG bursts and the initial knee flexion torques depended on initial paw position. Previous studies have shown that a shift in paw position prior to stepping over a barrier changes the paw trajectory to be appropriate for the new paw position. Our data indicate that both mechanical and neuronal factors contribute to this updating process, and that any shift in leg position during the delay period modifies the working memory of barrier location.

Jumping mechanisms and strategies in moths (Lepidoptera).

To test whether jumping launches moths into the air, take-off by 58 species, ranging in mass from 0.1 to 220 mg, was captured in videos at 1000 frames s(-1). Three strategies for jumping were identified. First, rapid movements of both middle and hind legs provided propulsion while the wings remained closed. Second, middle and hind legs again provided propulsion but the wings now opened and flapped after take-off. Third, wing and leg movements both began before take-off and led to an earlier transition to powered flight. The middle and hind legs were of similar lengths and were between 10 and 130% longer than the front legs. The rapid depression of the trochantera and extension of the middle tibiae began some 3 ms before similar movements of the hind legs, but their tarsi lost contact with the ground before take-off. Acceleration times ranged from 10 ms in the lightest moths to 25 ms in the heaviest ones. Peak take-off velocities varied from 0.6 to 0.9 m s(-1) in all moths, with the fastest jump achieving a velocity of 1.2 m s(-1). The energy required to generate the fastest jumps was 1.1 µJ in lighter moths but rose to 62.1 µJ in heavier ones. Mean accelerations ranged from 26 to 90 m s(-2) and a maximum force of 9 G: was experienced. The highest power output was within the capability of normal muscle so that jumps were powered by direct contractions of muscles without catapult mechanisms or energy storage.

Evaluation of serum anti-Müllerian hormone (AMH) in a Persian queen cat with bilateral cystic ovarian disease

Measurement of anti-Mullerian hormone (AMH) is applied to diagnose polycystic ovary syndrome in human. A 7-year-old female Persian cat was presented for persistent expression of behavioural oestrus. In response to examination of spines, the queen exhibited treading movements of hind legs. Trans-abdominal ultrasonography revealed a multicystic appearance of both ovaries. Oestradiol in the queen with prolonged oestrus (145 pg/ml) was higher than that in normal oestrous cats (50.8 ± 7.41 pg/ml). However, AMH concentration in the cat with prolonged oestrus (1.8 ng/ml) was within the range of AMH concentration in normal oestrous queens (3.5 ± 0.81 ng/ml; range, 1.2–5.8 ng/ml). The queen was diagnosed with cystic ovarian disease and was subjected to ovariohysterectomy. Excision and histopathology confirmed cystic ovarian disease as well as uterine hyperplasia. In conclusion, it seems that AMH could not serve as a diagnostic indicator of cystic ovarian disease in cat.

Antibody Labelling of Resilin in Energy Stores for Jumping in Plant Sucking Insects

The rubbery protein resilin appears to form an integral part of the energy storage structures that enable many insects to jump by using a catapult mechanism. In plant sucking bugs that jump (Hemiptera, Auchenorrhyncha), the energy generated by the slow contractions of huge thoracic jumping muscles is stored by bending composite bow-shaped parts of the internal thoracic skeleton. Sudden recoil of these bows powers the rapid and simultaneous movements of both hind legs that in turn propel a jump. Until now, identification of resilin at these storage sites has depended exclusively upon characteristics that may not be specific: its fluorescence when illuminated with specific wavelengths of ultraviolet (UV) light and extinction of that fluorescence at low pH. To consolidate identification we have labelled the cuticular structures involved with an antibody raised against a product of the Drosophila CG15920 gene. This encodes pro-resilin, the first exon of which was expressed in E. coli and used to raise the antibody. We show that in frozen sections from two species, the antibody labels precisely those parts of the metathoracic energy stores that fluoresce under UV illumination. The presence of resilin in these insects is thus now further supported by a molecular criterion that is immunohistochemically specific.

Pre–emptive meloxicam for postoperative analgesia in piglets undergoing surgical castration

ObjectiveTo investigate the effect of preoperative meloxicam administration on postoperative stress and pain induced by surgical castration in piglets. Study designProspective, blinded, randomized clinical trial. AnimalsOne hundred and eighty male piglets of <1 week of age. MethodsCastration was performed on 150 piglets which had received either an intramuscular injection of 0.4 mg kg−1 meloxicam or a placebo 10–30 minutes before the procedure. Blood cortisol and ACTH concentrations were determined at 30 minutes post–castration and haptoglobin was measured at 24 hours post–castration. Presence or absence of foreleg movements, hind leg movements, urine or faeces emission, tremors or other body movements were recorded during the castration procedure. Scores for presence or absence of prostration, tremors, tail movements and isolation were recorded at 30 minutes, and at 1, 2, 4 and 24 hours post–castration and combined in a global behaviour score (GBS). Blood samples were taken from a further 30 piglets which did not undergo castration. ResultsMean blood cortisol and ACTH concentrations at 30 minutes post–castration were both significantly lower in the meloxicam group than in the placebo group (p ≤ 0.01). The mean haptoglobin concentration at 24 hours was not significantly reduced (p = 0.178). The distribution of the GBS during castration was similar in both groups. There were significant differences in the GBS after castration at both 2 and 4 hours post–castration with a greater proportion of piglets in the meloxicam group showing no behavioural alterations (82.7%versus 68.0% at both time points). The score distribution was similar in both groups at 30 minutes, 1 and 24 hours after castration. Conclusion and clinical relevanceThis study suggests that pre–emptive administration of meloxicam is able to produce some postoperative analgesia after surgical castration of young piglets.

Energy storage and synchronisation of hind leg movements during jumping in planthopper insects (Hemiptera, Issidae)

The hind legs of Issus (Hemiptera, Issidae) move in the same plane underneath the body, an arrangement that means they must also move synchronously to power jumping. Moreover, they move so quickly that energy must be stored before a jump and then released suddenly. High speed imaging and analysis of the mechanics of the proximal joints of the hind legs show that mechanical mechanisms ensure both synchrony of movements and energy storage. The hind trochantera move first in jumping and are synchronised to within 30 micros. Synchrony is achieved by mechanical interactions between small protrusions from each trochantera which fluoresce bright blue under specific wavelengths of ultra-violet light and which touch at the midline when the legs are cocked before a jump. In dead Issus, a depression force applied to a cocked hind leg, or to the tendon of its trochanteral depressor muscle causes a simultaneous depression of both hind legs. The protrusion of the hind leg that moves first nudges the other hind leg so that both move synchronously. Contractions of the trochanteral depressor muscles that precede a jump bend the metathoracic pleural arches of the internal skeleton. Large areas of these bow-shaped structures fluoresce bright blue in ultraviolet light, and the intensity of this fluorescence depends on the pH of the bathing saline. These are key signatures of the rubber-like protein resilin. The remainder of a pleural arch consists of stiff cuticle. Bending these composite structures stores energy and their recoil powers jumping.

New technique for drug application to the spinal cord of walking mice

With the increasing availability of mutant mice that allow the conditional silencing of specific classes of interneurons in the spinal cord by drug application, a method for easily delivering drugs locally on spinal cord segments in adult animals has the potential for providing insights into the functioning of neuronal networks controlling walking. Here we describe a simple technique for this purpose. The drug is applied in high concentrations in a bath created with Vaseline walls around one to three segments of the spinal cord exposed under general anesthetic (isoflurane) combined with a strong, long-lasting analgesic (buprenorphine). After 20 min of drug application the Vaseline and the drug is removed and skin closed. We first document that the surgery and analgesic have no obvious influences on the kinematics of hind leg movements after recovery from the anesthetic, and that the analgesic enhanced locomotor activity. We then describe the influence of applying a glycine-receptor antagonist onto the lumbar segments of the spinal cord to demonstrate that the method is effective in modifying the functioning of neuronal systems in the spinal cord. Combining this method with kinematic and electromyographic recording techniques allows the detailed investigation of the effects of drugs on the walking behavior in adult mice.

Intrathecal Magnesium Sulfate Administration at the Time of Experimental Ischemia Improves Neurological Functioning by Reducing Acute and Delayed Loss of Motor Neurons in the Spinal Cord

In this study, the authors determined the effect of magnesium sulfate on intrathecal glutamate concentrations, hindlimb motor function, and histopathology after a transient episode of spinal cord ischemia. Fifty-two New Zealand White rabbits underwent spinal cord ischemia for 30 min. Fifteen minutes before ischemia, animals received intrathecal magnesium sulfate (MgSO4) (3 mg/kg) or placebo (artificial cerebrospinal fluid). Intrathecal microdialysis samples were measured for glutamate using high-performance liquid chromatography. Neurologic function and spinal cord histopathology were assessed throughout the recovery period. Intrathecal glutamate levels in placebo-treated animals were higher after spinal cord ischemia compared with sham- and MgSO4-treated animals. MgSO4-treated animals had increased lower extremity motor function compared with the placebo group (64.7% vs 14.3%, P < 0.01). Histologic examination of placebo-treated animals revealed significant motor neuron cell loss at thoracolumbar levels by Day 7 (P < 0.05), whereas lower lumbar regions displayed significant neuron loss on Day 1. Spinal cords from MgSO4-treated animals exhibited less neuronal loss in lumbar regions. Similar effects were present in the thoracolumbar segments on Day 7. A significant correlation existed between diminished neuronal loss and hind leg movement (Tarlov score) and demonstrates that the neurologic outcome after MgSO4 treatment was related to lower lumbar ventral horn cell survival (r2 = 0.812, P < 0.001). These results demonstrate that MgSO4 affords significant spinal cord motor neuron protection by diminishing acute neuronal loss at the foci of the ischemic injury (L3-L6) with delayed neuronal degeneration in adjacent spinal cord regions (T7-L2).

Motor Control of Aimed Limb Movements in an Insect

Limb movements that are aimed toward tactile stimuli of the body provide a powerful paradigm with which to study the transformation of motor activity into context-dependent action. We relate the activity of excitatory motor neurons of the locust femoro-tibial joint to the consequent kinematics of hind leg movements made during aimed scratching. There is posture-dependence of motor neuron activity, which is stronger in large amplitude (putative fast) than in small (putative slow and intermediate) motor neurons. We relate this posture dependency to biomechanical aspects of the musculo-skeletal system and explain the occurrence of passive tibial movements that occur in the absence of agonistic motor activity. There is little recorded co-activation of antagonistic tibial extensor and flexor motor neurons, and there is differential recruitment of proximal and distal flexor motor neurons. Large-amplitude motor neurons are often recruited soon after a switch in joint movement direction. Motor bursts containing large-amplitude spikes exhibit high spike rates of small-amplitude motor neurons. The fast extensor tibiae neuron, when recruited, exhibits a pattern of activity quite different to that seen during kicking, jumping, or righting: there is no co-activation of flexor motor neurons and no full tibial flexion. Changes in femoro-tibial joint angle and angular velocity are most strongly dependent on variations in the number of motor neuron spikes and the duration of motor bursts rather than on firing frequency. Our data demonstrate how aimed scratching movements result from interactions between biomechanical features of the musculo-skeletal system and patterns of motor neuron recruitment.

Biologically realistic walking pattern emulator using linear electro-mechanical actuators with augmented nonlinear control

The hind leg movement of a cat has four basic phases called Stance, Lift off, Swing and Touch down. In this research project, the complete movement of each hind leg in a vertical plane is assumed to be obtained by proper activation of seven muscles. The final target here is to propose suitable design suggestions for a linear electromechanical actuator, which could successfully emulate dynamic properties of a muscle, when augmented with nonlinear behaviours of real muscles using control. This paper will describe the proposed control methodology.

Effects of combination of melatonin and dexamethasone on secondary injury in an experimental mice model of spinal cord trauma

This study investigates the effects of combination therapy with melatonin and dexamethasone on the degree of spinal cord injury caused by the application of vascular clip in mice. Spinal cord injury in mice resulted in severe trauma, characterized by edema, neutrophil infiltration, and apoptosis (measured by terminal deoxynucleotidyltransferase-mediated UTP end labeling staining, and immunoreaction of Bax, Bcl-2, and Fas Ligand). Infiltration of the spinal cord tissue with neutrophils (measured as increase in myeloperoxidase activity) was associated with enhanced immuno- histochemical and functional alterations revealed, respectively, by an increased of tumor necrosis factor (TNF)-alpha immunoreactivity, NOS as well as nitrotyrosine and loss of hind leg movement in spinal cord injury (SCI)-operated mice. In contrast, the degree of neutrophil infiltration at different time points, cytokine expression, histologic damage iNOS expression, apoptosis, was markedly reduced in the tissues obtained from SCI-treated mice with the combination therapy, and the motor recovery was also ameliorated. No anti-inflammatory effect was observed in animals treated with melatonin (10 mg/kg) or with dexamethasone (0.025 mg/kg) alone. This study shows that the combination therapy with melatonin and dexamethasone reduces the degree of secondary damage associated with spinal cord injury in mice, and supports the possible use of melatonin in combination with steroids to reduce the dose and the side effects related with the use of steroids for the management of inflammatory disease.

Behavioral and Electromyographic Characterization of Mice Lacking EphA4 Receptors

EphA4 receptors play an important role in axon guidance during development. Disrupting the expression of these receptors in mice has been shown to modify neuronal connections in the spinal cord and results in the production of a characteristic hopping gait. The EphA4-null mouse has been used in numerous investigations aimed at establishing mechanisms responsible for patterning motor activity during walking. However, there have been no detailed behavioral or electrophysiological studies on adult EphA4-null mice. We used high-speed video recordings to determine the coordination of leg movements during locomotion in adult EphA4-null mice. Our data show that the hopping movements of the hind legs are not always associated with synchronous movements of forelegs. The coupling between the forelegs is weak, resulting in changes in their phase relationship from step to step. The synchronous coordination of the hind legs can switch to an alternating pattern for a short period of time during recovery from isoflurane anesthesia. Comparison of the kinematics of hind leg movements in EphA4-null mice and wild-type animals shows that besides the synchronous coordination in EphA4-null mice, the swing durations and the swing amplitude are shorter. Electromyographic recordings from a knee extensor muscle show double bursting in the EphA4-null animals but single bursts in wild types. This double burst changes to single-burst activity during swimming and when hind legs are stepping in alternation. These observations suggest an influence of sensory feedback in shaping the pattern of muscle activity during locomotion in the mutant animals. Our data give the first detailed description of the locomotor behavior of an adult mouse with genetically manipulated spinal networks.

A functional analysis of how frogs jump out of water

Euphlyctis cyanophlyctis and E. hexadactylus are two common frog species from south-east Asia. Both species have the remarkable ability to leap from a floating position out of the water. Rana esculenta is a European species from the same family that barely manages to do so. The species' morphology, however, looks roughly the same. We studied the unique abilities of the Euphlyctis species by videotaping the three species mentioned above whilst they jumped out of the water. These recordings enabled us to study the hind leg movements and to test several hypotheses. Dif- ferences between the species only became apparent when details of the behaviour were analysed. The three species mainly differed in their slip factor at the start of the propulsive phase, resulting in a difference in slip distance. This difference could be traced back to the difference in web shape by means of a physical model. The Euphlyctis species can prevent their feet from slipping because of their rounded and convex webbing, resulting in a larger take-off veloc- ity and thereby a successful emergence out of the water. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 413-420. ADDITIONAL KEYWORDS: Anura - locomotion - movement analysis - physical model.