Limb Placement Research Articles

Reducing trailing limb collisions in older adults through targeted leading limb placement after obstacle crossing: effect of closer foot placement

IntroductionOlder adults experience a higher frequency of collisions with obstacles when stepping over obstacles, particularly with the trailing limb. We recently demonstrated that placing the leading limb closer to an obstacle after crossing effectively increases the toe height of the trailing limb, resulting in reduced collision. This study investigated whether the intervention of placing the leading limb closer to the obstacle is effective in reducing trailing limb collisions in healthy older adults.MethodsTwenty-one older individuals (11 males, 10 females; mean age 75.7 years) participated. Participants were allocated to one of two groups: a closer placement group, instructed to place the leading limb on a square target positioned on their walking path after crossing an obstacle, and a control group, instructed to cross the obstacle naturally. The target in the closer group was set at 0.5 times the leading limb's foot placement distance, as determined in a pre-test for each participant. The experimental design included a pre-test, intervention, and post-test.Results and discussionThe collision rate for the trailing limb in the closer group was significantly lower in the post-test than that in the pre-test. Furthermore, the variability in toe height and walking speed of the trailing limb in the closer group decreased significantly in the post-test compared to the pre-test. These findings suggest that the intervention of placing the leading limb foot closer to the obstacle after crossing may improve obstacle avoidance by the trailing limb in healthy older adults.

Modified torso vs distal limb electrode placement for performing ECGs in children: A method comparison study

BackgroundThe electrocardiogram (ECG) is routinely performed in children with the limb electrodes positioned on the torso, but few studies have investigated the effects of this modification on the pediatric ECG. Our objective was to assess the agreement between the standard limb lead configuration and a modified torso electrode configuration in normal, healthy children, and to assess the effect of height on that agreement. Methods185 children aged 5–18 years underwent two consecutive 12‑lead ECGs, one with standard distal limb lead placement and one with the limb leads placed on the torso. Agreement was assessed for 17 ECG parameters (intervals, axes, and amplitudes) using Bland-Altman plots, height-dependent mean error, and false positive rates. ResultsThe torso configuration systematically biased the QRS and P wave axes rightwards (towards aVF). Adequate agreement was observed for PR interval and QRS duration, but QTc limits of agreement (±40 ms) were wide. The torso configuration overestimated left-precordial Q, R, and S wave amplitudes and underestimated right-precordial R and S wave amplitudes compared to the distal limb placement. Mean measurement errors increased with the magnitude of the ECG parameter. Mean and variance of measurement errors were more pronounced in shorter children. False positive rates did not differ between the torso and distal limb configurations. ConclusionModified placement of the limb electrodes onto the torso resulted in multiple differences in the pediatric ECG signals. This may lead to misclassification of electrocardiographic abnormalities, particularly in children with measurement values at the upper limits of normal.

КОГНИТИВНЫЙ И НЕВРОЛОГИЧЕСКИЙ СТАТУС КРЫС ПОСЛЕ МОДЕЛИРОВАНИЯ ОСТРОЙ ЧЕРЕПНО-МОЗГОВОЙ ТРАВМЫ НА ФОНЕ ПРИМЕНЕНИЯ РАЗЛИЧНЫХ КОНЦЕНТРАЦИЙ КСЕНОНА

The study aims to evaluate the efficacy of xenon inhalation at various concentrations on neurological and cognitive impairments when simulating open traumatic brain injury (TBI) in rats. Tests were performed on 35 male Wistar rats weighing from 250 to 350 g. After simulating an open traumatic brain injury, the animals received inhalation with a mixture of gases: 5 sham operated animals received only anesthesia without traumatic brain injury and inhalations, a control group with traumatic brain injury + inhalation N2 70 % / O2 30 % (group “TBI”, n = 10); an experimental group with traumatic brain injury + inhalation of xenon-oxygen 70 % / O2 30 % (group “TBI + iXe70”, n = 10), an experimental group with traumatic brain injury + inhalation of xenon-oxygen and nitrogen – Xe 35 % / O2 30 %, nitrogen 35 % (group “TBI + iXe + N2”, n = 10) for 60 minutes. After gas inhalation, the animals were observed for 14 days. On the 3rd, 7th and 14th days, the neurological limb placement test was carried out. The preservation of cognitive functions, such as learning and spatial memory, was assessed using the Morris water maze test with control testing on the 14th day. After testing, on the 14th day of observation, euthanasia was performed, and the brain was collected for research. It was found that the selected xenon concentrations in doses of 0.25 and 0.5 MAC tatistically significantly reduced the severity of both neurological deficit and cognitive impairment in 7 and 14 days, whereas increasing the xenon concentration did not significantly enhance the neuroprotective effect.

Positive Neuroprotective Effect of Argon Inhalation after Photochemically Induced Ischemic Stroke Model in Rats.

We studied the effect of 2-h inhalation of argon-oxygen mixture (Ar 70%/O2 30%) after photochemically induced stroke and on days 2 and 3 after stroke modeling on the severity of neurological deficit and brain damage (by MRI data) in Wistar rats. Neurological deficit was assessed within 14 days using the limb placement test. MRI and histological study of the brain with an assessment of the size of damage were performed on day 14 after ischemia. Significant differences were obtained in limb placement scores on days 3, 7, and 14, as well as in the volume of ischemic focus by MRI in comparison with the control (ischemia+N2 70%/O2 30%). Inhalation of argon-oxygen mixture for 2 h a day over 3 days after photoinduced stroke decreased the volume of brain damage by 2 times and reduced the severity of neurological deficit.

Experimental Study of Neuroprotective Properties of Inhaled Argon-Oxygen Mixture in a Photoinduced Ischemic Stroke Model

Acute ischemic stroke is a serious problem for healthcare systems worldwide. Searching for the optimal neuroprotector is a contemporary challenge. Various studies have demonstrated neuroprotective properties of argon in ischemic brain damage models. However, the published data are inconsistent.The aim of the study was to evaluate the effect of 24-hour argon-oxygen mixture (Ar 70%/O₂ 30%) inhalation on the severity of neurological deficit and the extent of brain damage in rats after a photoinduced ischemic stroke. Material and methods. The experiments were carried out on male Wistar rats weighing 430–530 g (N=26). Focal ischemic stroke was modeled in the sensorimotor cortex of the rat brain using photochemically induced vascular thrombosis. The animals were randomly divided into 3 groups: sham procedure + N₂ 70%/O₂ 30% inhalation (SP, N=6); stroke + N₂ 70%/O₂ 30% inhalation (Stroke, N=10); Stroke + Ar 70%/O₂ 30% inhalation (Stroke+iAr, N=10). The limb placement test (LPT) was used for neurological assessment during 14 days. Additionally, on day 14 after the stroke, brain MRI with lesion size morphometry was performed. Summarized for days 3,7 and 14 LPT scores were lower in the Stroke and Stroke + iAr groups as compared to the SP group.Results. Statistically significant differences in LPT scores between SP, Stroke, and Stroke+iAr groups were revealed on day 3 post-stroke: (scores: 14 (13; 14), 6.5 (4; 8), and 5 (3; 8), respectively, P=0.027). However, there was no statistical difference between the Stroke and Stroke+iAr groups.Conclusion. 24-hour inhalation of argon-oxygen mixture (Ar 70%/O₂ 30%) after stroke does not reduce the extent of brain damage or the severity of neurological deficit.

Evaluation of lower limb and pelvic marker placement precision among different evaluators and its impact on gait kinematics computed with the Conventional Gait Model

BackgroundGait analysis relies on the accurate and precise identification of anatomical landmarks to provide reliable and reproducible data. More specifically, the precision of marker placement among repeated measurements is responsible for increased variability in the output gait data. Research questionThe objective of this study was to quantify the precision of marker placement on the lower limbs by a test-retest procedure and to investigate its propagation to kinematic data. MethodsThe protocol was tested on a cohort of eight asymptomatic adults involving four evaluators, with different levels of experience. Each evaluator performed, three repeated marker placements for each participant. The standard deviation was used to calculate the precision of the marker placement, the precision of the orientation of the anatomical (segment) coordinate systems, and the precision of the lower limb kinematics. In addition, one-way ANOVA was used to compare the intra-evaluator marker placement precision and kinematic precisions among the different levels of the evaluator’s experience. Finally, a Pearson correlation between marker placement precision and kinematic precision was analyzed. ResultsResults have shown a precision of skin markers within 10 mm and 12 mm for intra-evaluator and inter-evaluator, respectively. Analysis of kinematic data showed good to moderate reliability for all parameters apart from hip and knee rotation that demonstrated poor intra- and inter-evaluator precision. Inter-trial variability was observed reduced than intra- and inter-evaluator variability. Moreover, experience had a positive impact on kinematic reliability since evaluators with higher experience showed a statistically significant increase in precision for most kinematic parameters. However, no correlation was observed between marker placement precision and kinematic precision which indicates that an error in the placement of one specific marker can be compensated or enhanced, in a non-linear way, by an error in the placement of other markers.

Abstract TP211: Recombinant Growth Differentiation Factor 11 Treatment Improves Functional Outcome In A Rat Permanent Ischemia Model Of Subacute Stroke

Introduction: GDF11 is a pleiotropic circulating blood factor and member of the transforming growth factor β (TGFβ) superfamily. In animal models of stroke, GDF11 is linked to regeneration and recovery through neovascularization, neurogenesis, and anti-inflammatory effects, among other potential mechanisms. Methods: Focal cerebral infarcts were made by permanent occlusion of the proximal right middle cerebral artery (MCA) by microbipolar coagulation, following a modification of the method of Tamura et al. rGDF11 or vehicle was delivered via multiple routes of administration to male Sprague Dawley Rats at single and multiple doses ranging from 0.1 - 4 mg/kg per dose. Dosing started ~24 hours following injury. Behavioral assessments (e.g., limb placement and body swing) were captured at days 3, 5, 7, 14, 21, and 28 post-injury. Results: Dose-dependent improvements in all behavioral assessments were seen at all animals receiving any dose level or frequency of rGDF11. Vehicle vs. rGDF11 comparisons yielded statistically significant improvements (p < 0.05) in all 3 behavioral assessments at several post-injury timepoints, including follow-up days 14 & 28. No major tolerability events were observed, and no animals were lost during the study. Histologic and serum markers indicated rGDF11’s beneficial effects on neovascularization, neurogenesis, and inflammation. Conclusions: Treatment of pMCAO rats with rGDF11 ~24hrs post-injury resulted in dose-dependent, durable improvements in motor function-focused behavioral assessments. These data support continued development of the potential clinical therapeutic application of rGDF11 in stroke and related disorders.

Pre-clinical efficacy evaluation of human umbilical cord mesenchymal stem cells for ischemic stroke.

This study explored the underlying therapeutic mechanism of human umbilical cord mesenchymal stem cells (hUCMSCs) for ischemic stroke (IS), and determined the optimal administration time windows and dose-effect relationship. The levels of SDF-1α, IL-10, IL-6, TNF-α, BDNF, IL-1β, and VEGF-A factors in serum and brain tissue lysate were measured by ELISA. The pathological status of brain tissues was evaluated by Hematoxylin-Eosin (HE) staining, and apoptosis of nerve cells was detected by tunel. The protein expression of CXCR-4, NeuN, and Nestin in the brain tissues was assessed through immunofluorescence. The balance beam, forelimb muscle strength, and limb placement were tested on MCAO rats at different time points and doses. The infarct area of the rat brain tissues was measured at the end of the experiment. The hUCMSC treatment during the acute phase of MCAO significantly reduced the secretion of IL-6, TNF-α, IL-1β but increased IL-10 in serum, and the levels of SDF-α and BDNF in serum and brain tissues lysate were also increased. The pathological results showed that there were more neurons in the treatment group compared to the model group. Immunofluorescence assays showed that the expression of CXCR4、Nestin、NeuN was relatively higher than that in the model group. The d4 and d7 treatment significantly improves the motor function, promotes the recovery of forelimb muscle strength, increases the forelimb placement rate and reduces the scope of cerebral infarction, but the d14 treatment group has less therapeutic effect compared to the d4 and d7 treatment. The 2×107/kg treatment showed the best therapeutic effect, followed by the 1×107/kg treatment, and the worst is 0.5×107/kg treatment from the test of balance beam, forelimb muscle strength, limb placement and the infarct area of the rat brain tissues. The hUCMSCs can inhibit the infiltration of inflammatory cells in the brain tissue, and promote the repair of brain tissue structure and function. Early intervention by injecting high-dose of hUCMSCs can significantly improve the recovery of neurological/motor function and reduce the size of cerebral infarction in rats.

НЕЙРОПРОТЕКТИВНЫЕ ЭФФЕКТЫ КРИПТОНА ПРИ ФОТОИНДУЦИРОВАННОМ ИШЕМИЧЕСКОМ ИНСУЛЬТЕ У КРЫС

The study aims to assess the effect of a two-hour inhalation with a krypton and oxygen mixture following the photo-induced cerebral infarction simulation on the manifestation of neurological deficits and the degree of brain injury in rats. The tests were conducted on male Wistar rats weighting 250 to 300 g (n = 20). Following photo-induced cerebral infarction simulation, the rodents underwent inhalation with a nitrogen and oxygen mixture N2 70%/O2 30% (group Nitrogen; n = 10) or a krypton and oxygen gas mixture Kr 70%/O2 30% (group Krypton; n = 10) for two hours. For the next 14 days, the rats were examined. On the 3rd, 7th, and 14th days, the authors performed a neurological test Limb placement, as well as euthanasia and brain removal for histological and mmunohistochemical examinations. It was determined that a two-hour inhalation with a krypton and oxygen gas mixture substantiated more prominent rehabilitation of rats’ neurological states by the seventh day, as well as increased the reparation and regeneration of their injured brains.

Effects of Feedback of Fingertip Force Information with Temporal Coded Vibration Stimulation on Precision Grasping Tasks

Tactile information plays an important role in human manipulation of objects; however, prosthetic limb placement or teleoperation requires the manipulation of alternative bodies in the absence of tactile sensations. To provide an alternative to tactile sensation, this study proposes and assesses a continuous feedback scheme with temporally coded vibration. This scheme was designed to provide discrete intended tactile information in response to changing object-controlled situations by repetitively presenting time-coded vibration patterns. The effects of the proposed scheme on an object with acatch-and-hold task in virtual reality were confirmed. Compared to the control feedback scheme that provides vibration only when the balance of the virtual grip force and object position is changed, the proposed feedback scheme has a better effect in terms of the success rate of holding on to the object with an appropriate holding force during the task. The effect is larger, especially in the invisible task condition, suggesting that the increased amount of information with coded vibration patterns can be used without any special training, especially without visual information. Considering the existing studies that show the effect of a feedback scheme in response to motion events, the continuous feedback scheme proposed in this study may be more suitable for movements that require sequential coordination and passive responses than stimulation methods based on motion events. This feedback scheme has potential applications not only in tele-technology but also in healthcare, such as rehabilitation.

Inhibition of the LRRC8A channel promotes microglia/macrophage phagocytosis and improves outcomes after intracerebral hemorrhagic stroke.

Promoting microglial/macrophage (M/Mφ) phagocytosis accelerates hematoma clearance and improves the prognosis of intracerebral hemorrhagic stroke (ICH). Cation channels such as Piezo1 modulate bacterial clearance by regulating M/Mφ. Whether LRRC8A, an anion channel, affects M/Mφ erythrophagocytosis and functional recovery after ICH was investigated here. We found that LRRC8A is highly expressed on M/Mφ in the perihematomal region of ICH mice. Conditional knockout of Lrrc8a in M/Mφ or treatment with an LRRC8A channel blocker accelerated hematoma clearance, reduced neuronal death, and improved functional recovery after ICH. Mechanistically, the LRRC8A channel inhibition promoted M/Mφ phagocytosis by activating AMP-activated protein kinase (AMPK), thereby inducing nuclear translocation of nuclear factor-erythroid 2 related factor 2 (Nrf2) and increasing Cd36 transcription. Our findings illuminate the regulation of M/Mφ phagocytosis by the LRRC8A channel via the AMPK-Nrf2-CD36 pathway after ICH, suggesting that LRRC8A is a potential target for hematoma clearance in ICH treatment.

Estimation of skeletal kinematics in freely moving rodents

Forming a complete picture of the relationship between neural activity and skeletal kinematics requires quantification of skeletal joint biomechanics during free behavior; however, without detailed knowledge of the underlying skeletal motion, inferring limb kinematics using surface-tracking approaches is difficult, especially for animals where the relationship between the surface and underlying skeleton changes during motion. Here we developed a videography-based method enabling detailed three-dimensional kinematic quantification of an anatomically defined skeleton in untethered freely behaving rats and mice. This skeleton-based model was constrained using anatomical principles and joint motion limits and provided skeletal pose estimates for a range of body sizes, even when limbs were occluded. Model-inferred limb positions and joint kinematics during gait and gap-crossing behaviors were verified by direct measurement of either limb placement or limb kinematics using inertial measurement units. Together we show that complex decision-making behaviors can be accurately reconstructed at the level of skeletal kinematics using our anatomically constrained model.

Выраженность когнитивных и неврологических нарушений у крыс после ишемического инсульта на фоне применения ксенона 0,5 МАК

The majority of stroke patients have cognitive symptoms and about 50% of them live with neurological deficits that critically limit social adaptation capacities even in the absence of significant motor impairments. The aim of this study was to select the optimal length of 0.5 MAC xenon exposure in order to alleviate the neurological and cognitive impairments in experimental stroke. The focal ischemia-reperfusion injury was modeled in rats (n = 70) ising Longa method. The intervention was immediately followed by inhalation of 0.5 MAC xenon for 30, 60 or 120 min. The neurological deficit was assessed using a 'Limb placement' seven-test battery and the cognitive functionalities were assessed by the Morris water maze test. A 30 min 0.5 MAC xenon exposure provided a 40% increase in the limb placement scores and a 17.6% decrease in the Morris water maze test latency compared with the control group (р = 0.055 and р = 0.08, respectively). With a longer 60 min exposure, the trends became significant, the scores improving 2-fold and by 44.4% compared with the control group (р = 0.01 and р = 0.04, respectively), whereas 120 min exposures afforded 2-fold improvements in both tests (р = 0.01). We conclude that, although 30 min post-stroke inhalations provide negligible benefits in terms of neurological status and learning capacity, prolonged exposure times of 60–120 min afford significant improvement in neurological and cognitive indicators and largely alleviate the deteriorating ischemic damage.

Evaluation of Lower Limb and Pelvic Marker Placement Precision Among Different Evaluators and its Impact on Gait Kinematics

Evaluation of Lower Limb and Pelvic Marker Placement Precision Among Different Evaluators and its Impact on Gait Kinematics

Trihydroxyethyl Rutin Provides Neuroprotection in Rats With Cervical Spinal Cord Hemi-Contusion.

Objective: To investigate the neuroprotective effects of trihydroxyethyl rutin in rats with cervical spinal cord hemi-contusion.Methods: Adult male Sprague–Dawley rats were subjected to hemi-contusion at a stroke depth of 1.2 mm, and then intraperitoneally injected with 50 or 100 mg/kg trihydroxyethyl rutin per day for 12 weeks (T50 and T100 groups, respectively). Changes in somatosensory evoked potentials (SEPs), motor evoked potentials (MEPs), and behavior were continuously monitored. At 12 weeks post-injury, immunohistochemical staining was performed to assess changes in cervical spinal cord microvascular morphology. Magnetic resonance imaging (MRI) scans were performed to examine end-stage injury in the cervical spinal cord, and Eriochrome cyanine-stained slices of spinal cord tissue were evaluated for injury.Results: There were no significant differences in biomechanical parameters among the spinal cord injury, T50 and T100 rat groups. At 3 days-post-injury, there was a significant decrease in grip strength. At 12 weeks post-injury, grip strength recovery was significantly better in the T50 and T100 groups than in the injury group. Compared with the injury group, the total limb placement frequency was significantly higher in the T50 group at 2, 4, 6, 10, and 12 weeks post-injury and in the T100 group at 2, 6, 8, and 10 weeks post-injury. Ipsilateral SEPs and MEPs were dynamic, increasing in latency and decreasing in amplitude in the injury compared with sham group. MRI scanning demonstrated that the coronal, sagittal, and transversal lesion areas were smaller in the T50 and T100 groups than in the injury group. Microvascular density showed a greater reduction in the injury group compared with the T50 and T100 groups. Eriochrome cyanine staining showed that the ipsilateral side, residual parenchyma, and gray matter areas were larger in the T50 and T100 groups than in the injury group.Conclusion: Trihydroxyethyl rutin exhibits robust neuroprotective effects, improving limb motor function and nerve electrophysiological parameters after spinal cord injury, maintaining microvascular density, and reducing the area of injury and degree of demyelination.

Application of Quality Control Circle Activity in Improving the Accuracy of Good Limb Placement in Hemiplegia Patients

Application of Quality Control Circle Activity in Improving the Accuracy of Good Limb Placement in Hemiplegia Patients

Massive Pontine Hemorrhage by Dual Injection of Autologous Blood.

We provide a protocol to establish a massive pontine hemorrhage model in a rat. Rats weighing about 250 grams were used in this study. One hundred microliters of autologous blood was taken from the tail vein and stereotaxically injected into the pons. The injection process was divided into 2 steps: First, 10 µL of blood was injected into a specific location, anteroposterior position (AP) -9.0 mm; lateral (Lat) 0 mm; vertical (Vert) -9.2 mm, followed by a second injection of the residual blood located at AP -9.0 mm; Lat 0 mm; Vert -9.0 mm with a 20-minute interval. The balance beam test, limb placement test, and the modified Voestch neuroscore were used to evaluate neurological function. Magnetic Resonance Imaging (MRI) was used to assess the volume of hemorrhage in vivo. The symptoms of this model were in line with patients with massive pontine hemorrhage.

Available Sensory Input Determines Motor Performance and Strategy in Early Blind and Sighted Short-Tailed Opossums.

SummaryThe early loss of vision results in a reorganized neocortex, affecting areas of the brain that process both the spared and lost senses, and leads to heightened abilities on discrimination tasks involving the spared senses. Here, we used performance measures and machine learning algorithms that quantify behavioral strategy to determine if and how early vision loss alters adaptive sensorimotor behavior. We tested opossums on a motor task involving somatosensation and found that early blind animals had increased limb placement accuracy compared with sighted controls, while showing similarities in crossing strategy. However, increased reliance on tactile inputs in early blind animals resulted in greater deficits in limb placement and behavioral flexibility when the whiskers were trimmed. These data show that compensatory cross-modal plasticity extends beyond sensory discrimination tasks to motor tasks involving the spared senses and highlights the importance of whiskers in guiding forelimb control.

Establishment of Acute Pontine Infarction in Rats by Electrical Stimulation.

Pontine infarction is the most common stroke subtype in the posterior circulation, while there lacks a rodent model mimicking pontine infarction. Provided here is a protocol for successfully establishing a rat model of acute pontine infarction. Rats weighing about 250 g are used, and a probe with an insulated sheath is injected into the pons using a stereotaxic apparatus. A lesion is produced by the electrical stimulation with a single pulse. The Longa score, Berderson score, and beam balance test are used to assess neurological deficits. Additionally, the adhesive-removal somatosensory test is used to determine sensorimotor function, and the limb placement test is used to evaluate proprioception. MRI scans are then used to assess the infarction in vivo, and TTC staining is used to confirm the infarction in vitro. Here, a successful infarction is identified that is located in the anterolateral basis of the rostral pons. In conclusion, a new method is described to establish an acute pontine infarction rat model.

Performance and Behavioral Flexibility on a Complex Motor Task Depend on Available Sensory Inputs in Early Blind and Sighted Short-Tailed Opossums

The early loss of vision results in a reorganization of visual cortex, which becomes commandeered by the somatosensory and auditory systems. Recent studies in the short-tailed opossum found that the connections and response properties of neurons in somatosensory cortex of blind animals are also altered. While studies in humans and other mammals show that early vision loss leads to heightened abilities on discrimination tasks involving the spared senses, if and how this superior discrimination leads to adaptive sensorimotor behavior has yet to be determined. Moreover, little is known about the extent to which blind animals rely on the spared senses. Here, we tested opossums on a sensorimotor task involving somatosensation. We found that early blind animals had increased limb placement accuracy compared to sighted controls, while showing similarities in crossing strategy. Whisker trimming nullified this advantage, resulting in decreases in limb placement accuracy and more variable forelimb movements in both groups. However, the increased reliance on tactile inputs in early blind animals led to greater deficits in limb placement and behavioral flexibility when the whiskers were trimmed. This data demonstrates that incoming sensory input from the whiskers is processed differently in the brains of early blind compared to sighted opossums, likely due, in part, to the dramatic changes to visual and somatosensory cortex. These results also provide direct evidence for the prevailing theory that the whiskers are critical for skilled forelimb control in whisking mammals, and highlight the importance of studying both performance and strategy when assessing differences in behavior.