Similar stretch reflexes and behavioral patterns are expressed by the dominant and non-dominant arms during postural control

Limb dominance is evident in many daily activities leading to the prominent idea that each hemisphere of the brain specializes in controlling different aspects of movement. Past studies suggest the dominant arm is primarily controlled via an internal model of limb dynamics that enables the nervous system to produce efficient movements. In contrast, the non-dominant arm may be primarily controlled via impedance mechanisms that rely on the strong modulation of sensory feedback from individual joints to control limb posture. We tested whether such differences are evident in behavioral responses and stretch reflexes following sudden displacement of the arm during posture control. Experiment 1 applied specific combinations of elbow-shoulder torque perturbations (the same for all participants). Peak joint displacements, return times, endpoint accuracy, and the directional tuning and amplitude of stretch reflexes in nearly all muscles were not statistically different between the two arms. Experiment 2 induced specific combinations of joint motion (the same for all participants). Again, peak joint displacements, return times, endpoint accuracy, and the directional tuning and amplitude of stretch reflexes in nearly all muscles did not differ statistically when countering the imposed loads with each arm. Moderate to strong correlations were found between stretch reflexes and behavioral responses to the perturbations with the two arms across both experiments. Collectively, the results do not support the idea that the dominant arm specializes in exploiting internal models and the non-dominant arm in impedance control by increasing reflex gains to counter sudden loads imposed on the arms during posture control.

The impact of percutaneous peripheral interventions on endothelial function

Summary: Background: Treatment of symptomatic peripheral artery disease (PAD) through endovascular interventions is the primary revascularization strategy. Interventions restore perfusion but may cause severe injury to the vascular endothelium, which regulates vascular tone. Endothelial dysfunction is involved in the progression of cardiovascular disease, with higher incidences of vascular events. We aimed to determine the impact of percutaneous interventions on change in endothelial function. Patients and methods: Endothelial function was determined using flow-mediated dilation (FMD) before, the day after lower limb intervention with paclitaxel-coated balloons or stent guided interventions and after a six-month follow-up in the target limb, control limb and the systemic circulation in 42 PAD patients aged 70.2±9 years and 66% men. Additionally, macro- and microvascular function were assessed. Results: In PAD patients aged 70.2±9 years and 66% men, we observed an immediate enhancement of macro-, microvascular and endothelial function after endovascular treatment (FMD of superficial femoral artery (SFA) 3.7±0.2% to 4.1±0.1%, n=42, p=0.02), a sustained long-term improvement after 6-months (FMD SFA 3.7±0.2% to 4.2±0.1%, n=42, p=0.01), and moreover an improved systemic endothelial function (FMD brachial artery 4.3±0.1% to 4.7±0.2, n=42, p=0.01) following peripheral interventions. Subgroup analysis however revealed that following paclitaxel-based percutaneous intervention, the paclitaxel dosage applied was inversely related to the chronic improvement in local endothelial function (r=−0.6, n=22, p=0.005) without evidence for systemic effects (r=−0.25, p=0.27). Conclusions: We demonstrate an improved local and systemic endothelial function after treatment of atherosclerotic peripheral disease with a distinguished response after endovascular intervention with higher dosage of applied paclitaxel restraining the benefits. Further studies have to determine the optimal interventional strategy with respect to different treatment modalities to maintain vessel functions.

Effects of Diacutaneous Fibrolysis on Passive Neuromuscular Response and Mechanosensitivity in Athletes with Hamstring Shortening: A Randomized Controlled Trial

Introduction. Diacutaneous Fibrolysis is defined as specific instrumental intervention to normalize function in the musculoskeletal system. It is considered a treatment method for the mechanical alterations of the locomotor system, and it is widely used in sports for therapeutic and preventive purposes. Despite the clinical benefits observed in different musculoskeletal conditions, the action mechanism of diacutaneous fibrolysis remains uncertain. There are no studies evaluating the neuromuscular response on the posterior muscular chain of the lower extremity in athletes, where overload, stiffness, and injury incidence are high. Objective. To evaluate the immediate, and 30 min post treatment effects of a single diacutaneous fibrolysis session on passive neuromuscular response and mechanosensitibity on hamstring and gluteus in athletes with shortening. Design. A randomized within participant clinical trial. Methods. Sixty-six athletes with hamstring shortening were included (PKE < 160). The lower limbs were randomized between the experimental limb and control limb, regardless of dominance. A single session of diacutaneous fibrolysis was applied to the posterior gluteus maximus, biceps femoris, and semitendinosus of the experimental lower limb whereas the control limb was not treated. Viscoelastic muscle properties (myotonometry), contractile muscle properties (tensomiography), and mechanosensitivity (algometry) were tested before treatment (T0), after treatment (T1), and 30 min post treatment (T2). Results. Regarding viscoelastic properties, in the intra-group analysis we found statistically significant differences in the experimental limb at T1, decreasing muscle stiffness in gluteus maximus (p < 0.042), in biceps femoris (p < 0.001) and in semitendinosus (p < 0.032). We also observed statistically significant differences in Tone decrease (p < 0.011) and relaxation increase (p < 0.001) in biceps femoris. At T2, the decrease in stiffness in all tested muscles was maintained (p < 0.05). There were statistically significant inter-groups differences in stiffness on gluteus (p < 0.048) and biceps femoris (p < 0.019) and in tone on biceps femoris (p < 0.009) compared to the control limb. For contractile properties, we only found statistically significant differences on maximal radial displacement (Dm) in gluteus, both control and experimental at T2 (p < 0.05) and in biceps femoris control (p < 0.030). No changes were found in the mechanosensitivity. Conclusions. A single session of diacutaneous fibrolysis produces changes in some parameters related to viscoelasticity properties of the biceps femoris and gluteus. There were no changes on contractile properties on semitendinosus. Only small changes on the contractile properties on the gluteus maximus and biceps femoris were found. No effect was found on the mechanosensitivity of the posterior chain muscles in athletes with hamstring shortening.

Talar and Subtalar T1ρ Relaxation Times in Limbs with and without Chronic Ankle Instability

Objective The primary aim was to determine differences in talocrural and subtalar joint (STJ) articular cartilage composition, using T1ρ magnetic resonance imaging (MRI) relaxation times, between limbs in individuals with unilateral chronic ankle instability (CAI) and compare with an uninjured control. Our secondary purpose was to determine the association between talocrural and STJ composition in limbs with and without CAI. Design T1ρ MRI relaxation times were collected on 15 CAI (11 females, 21.13 ± 1.81 years, body mass index [BMI] = 23.96 ± 2.74 kg/m2) and 15 uninjured control individuals (11 females, 21.07 ± 2.55 years, BMI = 24.59 ± 3.44 kg/m2). Talocrural cartilage was segmented manually to identify the overall talar dome. The SJT cartilage was segmented manually to identify the anterior, medial, and posterior regions of interest consistent with STJ anatomical articulations. For each segmented area, a T1ρ relaxation time mean and variability value was calculated. Greater T1ρ relaxation times were interpreted as decreased proteoglycan content. Results Individuals with CAI demonstrated a higher involved limb talocrural T1ρ mean and variability relative to their contralateral limb ( P < 0.05) and the healthy control limb ( P < 0.05). The CAI-involved limb also had a higher posterior STJ T1ρ mean relative to the healthy control limb ( P < 0.05). In healthy controls ( P < 0.05), but not the CAI-involved or contralateral limbs (p>0.05), talocrural and posterior STJ composition measures were positively associated. Conclusions Individuals with CAI have lower proteoglycan content in both the talocrural and posterior STJ in their involved limbs relative to the contralateral and a healthy control limb. Cartilage composition findings may be consistent with the early development of posttraumatic osteoarthritis.

Effect of intentional restriction of venous return on tissue oxygenation in a porcine model of acute limb ischemia

Introduction A sufficient oxygen supply to ischemic limb tissue is the most important requirement for wound healing and limb salvage. We investigated whether partial venous occlusion in the common iliac vein (CIV) causes a further increase of venous oxygenation in a porcine model of acute hindlimb ischemia. Materials and methods In 7 pigs, the model of acute hindlimb ischemia was created with intra-vascular embolization of the common iliac artery (CIA). The arterial and venous oxygen saturation was evaluated at different moments. Oxygen saturation was evaluated at baseline (T0), just after the arterial embolization (T1), at 10 minutes (T2), at 20 minutes (T3), and at 40 minutes (T4). Next, an intentional partial venous occlusion was achieved by inflating the vascular balloon at the level of the right CIV. Then, blood sampling was repeated at 5 minutes (T5), at 15 minutes (T6), and at 25 minutes (T7). Results The arterial oxygen saturation in the right SFA was similar during all phases. In contrast, after arterial embolization, an immediate reduction of venous oxygen saturation was observed (from 85.57 ± 1.72 at T0 to 71.86 ± 7.58 at T4). After the partial venous occlusion, interestingly, the venous oxygen saturations (T5-T7) were significantly increased, again. The venous oxygen saturations evaluated in the hindlimb ischemia with partial venous occlusion and in the control limb (without partial venous occlusion) were significantly over time. Venous oxygen saturations in the experimental limbs were higher than those in the control limbs (79.28 ± 4.82 vs 59.00 ± 2.82, p-value <0.001, 79.71 ± 4.78 vs 60.00 ± 4.24 at T7, p-value <0.001). Conclusions Partial venous occlusion results in an increase of venous oxygen saturation in the ischemic limb, while significant changes in venous oxygen saturation are not observed in the control limb. An explanation for this may be that the oxygen consumption in the limb tissue is increased because it gets congested with the partial venous occlusion in the right CIV.

Effect of diacutaneous fibrolysis on the muscular properties of gastrocnemius muscle

Diacutaneous fibrolysis is a noninvasive technique that has been shown to be effective in the treatment of musculoskeletal disorders such as shoulder pain, lateral epicondylalgia, patellofemoral pain syndrome and carpal tunnel syndrome. However, while diacutaneous fibrolysis is applied to soft tissue, its effects on muscular properties are unknown. The purpose of the present study was to evaluate the effects of diacutaneous fibrolysis on muscle properties as measured by tensiomyography and myotonometry in asymptomatic subjects. An analytical descriptive study was performed. A single session of diacutaneous fibrolysis on the gastrocnemius muscle was applied to one limb (treated limb group) and the other limb was the control (control limb group). Subjects were assessed with tensiomyography and myotonometry before treatment (T0), after treatment (T1) and 30 minutes later (T2). The primary outcomes were tensiomyography and myotonometry variables. The treated limb group showed a statistically significant increase (p<0.05) in tensiomyography parameters. A decrease in rigidity and increase in relaxation was also observed on myotonometry at T1, with some of the effects being maintained at T2. Rigidity and relaxation at T1 were statistically significant between groups (p<0.05). A single session of diacutaneous fibrolysis to the gastrocnemius muscle of asymptomatic subjects produced immediate changes in muscle properties. These changes were maintained 30 minutes after the application of the technique.

In vivo deuterated water labeling allows tumor visualization via deuterium magnetic resonance spectroscopic imaging of cholesterol

Water is an essential component of many biochemical reactions. Deuterated water (D2O) has been used to study cell kinetics, protein synthesis, and metabolism. We hypothesized that rapidly proliferating cancer cells would become preferentially labeled with deuterium due to high metabolic activity, thus allowing imaging of biosynthetically labeled metabolites within tumors in vivo. We initiated systemic D2O labeling in two established tumor xenograft models, HT-29 and MiaPaCa-2 and imaged mice by deuterium magnetic resonance spectroscopic imaging (dMRSI). After 14 days of tumor growth and 7 days of in vivo labeling, a clear contrast was demonstrated between the xenograft and the contralateral control limb in both models. The origin of the contrast was traced to an aliphatic peak at 1.8 ppm, which was identified by ex vivo NMR analysis to originate from cholesterol and cholesterol esters. Cholesterol is important for tumor cell proliferation, signaling, and malignant transformation, while current methods to monitor cholesterol synthesis and accumulation are limited. This deuterated water labeling-imaging approach could complement current cancer imaging techniques, allowing not only imaging of uptake but also synthesis of cholesterol to elucidate effects on tumor cholesterol metabolism in vivo.

A study of effect of tarsal tunnel decompression on sensory improvement in diabetic foot: a prospective randomized control trial

Background: In India approximately, 45000 legs are amputated every year and almost 75% of these amputations are carried out in neuropathic feet which are potentially preventable. Diabetic peripheral nerves are at risk of entrapment neuropathies focally, where these nerves are contained in a closed space. The aim of the study was to find out the effect of decompression of compressed posterior tibial nerve and its branches at tarsal tunnel in restoration of sensation in diabetic foot.Methods: A total of 70 diabetic patients with ulcer foot in one limb (test limb) and with no ulcer on the other limb (control limb) were selected for study. The test limb was subjected to tarsal tunnel release. Sensory recovery was evaluated in the ulcer limb and compared with normal limb in same patient and results were evaluated statistically for significance.Results: Present study shows that following tarsal tunnel decompression surgery on test limb, 65 patients (93%) had sensory gain and 5 patients (7%) had documented no sensory gain on test limb, with statistical significance. After de-compressive surgery on the test limb, 69 patients (98.6%) were documented to have resolving of Tinel sign in the test limb with sensory improvement, suggesting adequate decompression and 1 patient (1.4%) was documented to have persistent Tinel sign suggesting possibility of inadequate decompression with no recovery of sensation, with statistical significance.Conclusions: Present study reveals that decompression of tarsal tunnel in diabetic ulcer foot patients leads to definite improvement in sensation of foot which will prevent further ulcer formation and resultant complications ending in amputations.

Tarsal tunnel decompression: an effective method for prevention of foot complications in diabetic patients with compressive neuropathy at tarsal tunnel

Background: Diabetic foot is one of the most devastating complications of diabetes with 15% lifetime risk of developing ulcer foot. About 80% of diabetic foot is neuropathic in origin, revealing the importance of sensory sensation in preventing the development of diabetic ulcer. This study is aimed to identify the efficiency of tarsal tunnel decompression surgery in diabetic patients in ulcer healing and in the prevention of development of new diabetic related foot complications.Methods: About 70 diabetic patients with ulcer in one foot, acting as test limb and contralateral foot having no ulcer, acting as control limb was included in the study. Tarsal tunnel decompression surgery was done in the test limb and the status of ulcer in the test limb, in terms of diameter/ progress of ulcer healing was observed. In both the study limb and the control limb foot was examined for onset of any new diabetes related foot changes/complications during the follow up period for 18 months.Results: Postoperatively, at 6 weeks, 20 patients (28.6%) had their ulcers fully healed. At 3rd month postoperative follow up 90.48% of ulcers in the test limb showed complete healing following decompression surgery and 9.52% of ulcers showed partial healing. Following decompression surgery in the test limb, only 2 patients (3.28%) developed new diabetes related foot changes/complications as compared to control limb, where 15 patients (24.59%) developed new diabetes related foot changes/complications.Conclusions: Present study firmly proves that following tarsal tunnel decompression surgery, there is improvement in healing of the ulcer with conservative measures and there is a definitive role of tarsal tunnel decompression in prevention of development of new diabetes related foot changes/complications in patients.

Addition of blood flow restriction to passive mobilization reduces the rate of muscle wasting in elderly patients in the intensive care unit: a within-patient randomized trial

Objective: To evaluate the addition of blood flow restriction to passive mobilization in patients in the intensive care unit. Design: The study was a within-patient randomized trial. Setting: Two intensive care units in Belém, from September to October 2017. Subjects: In total, 34 coma patients admitted to the intensive care unit sector, and 20 patients fulfilled the study requirements. Interventions: All participants received the passive mobilization protocol for lower limbs, and blood flow restriction was added only for one side in a concurrent fashion. Intervention lasted the entire patient’s hospitalization time. Main outcome measurement: Thigh muscle thickness and circumference. Results: In total, 34 subjects were enrolled in the study: 11 were excluded for exclusion criteria, 3 for death, and 20 completed the intervention (17 men and 3 women; mean age: 66 ± 4.3 years). Despite both groups presented atrophy, the atrophy rate was lower in blood flow restriction limb in relation to the control limb (–2.1 vs. –2.8 mm, respectively, in muscle thickness; P = 0.001). In addition, the blood flow restriction limb also had a smaller reduction in the thigh circumference than the control limb (–2.5 vs. –3.6 cm, respectively; P = 0.001). Conclusion: The use of blood flow restriction did not present adverse effects and seems to be a valid strategy to reduce the magnitude of the rate of muscle wasting that occurs in intensive care unit patients.