Normal contractile algorithm of swallowing related muscles revealed by needle EMG and its comparison to videofluoroscopic swallowing study and high resolution manometry studies: A preliminary study

The purpose of this study was to investigate the function and importance of infrahyoid muscles with the suprahyoid muscles during swallowing, and to investigate swallowing sequences using kinematic analysis, high-resolution manometry (HRM) and electromyography (EMG). As a preliminary study, ten healthy subjects were prospectively enrolled. A needle EMG evaluated the onset latency, peak latency and duration of the suprahyoid and infrahyoid muscles. HRM measured the time intervals among the velopharynx, tongue base, and upper esophageal sphincter. We also evaluated hyoid motion using an automated kinematic analysis software® (AKAS). All of these parameters were synchronized with a tilting motion of the epiglottis. In the EMG analysis, the activations of the suprahyoid muscles developed about 300 ms earlier than that of the infrahyoid muscles. There was a significant relationship between the differences of suprahyoid and infrahyoid muscles’ latency and total duration of the hyoid motion (p < 0.05). The interval time of anterior hyoid motion has a significant correlation in the upper esophageal sphincter (UES) opening time. In conclusions, the functions of the infrahyoid muscles are also as important as that of the suprahyoid muscles for prolonged laryngeal elevation and UES opening. Moreover, kinematic analysis of videofluoroscopic swallowing study (VFSS) and HRM studies could reflect results of needle EMG study and replace EMG study.     

Decreased fibularis reflex response during inversion perturbations in FAI subjects

Investigate reflex responses in muscles throughout the lower limb and low back during sudden inversion perturbations in individuals with and without Functional Ankle Instability (FAI) while walking. Forty subjects participated in the study. Surface electromyogram recordings were obtained from the fibularis (FIB), gluteus medius (GM), erector spinae (ES), and sternocleidomastoid (SCM) of the injured/matched side as well as the uninjured/matched contralateral side (FIB_CLS, GM_CLS, or ES_CLS). Latency and amplitude data were collected while subjects were walking on a custom-built perturbation walkway. The onset of the short-latency stretch reflex of the FIB was significantly later in the injured side of the FAI individuals when compared to the control group (P = 0.009). Both the short and long latency reflex amplitude was significantly smaller in the FIB muscle in the FAI group than in the control group (P < 0.008). No significant differences in latency or amplitude reflex responses were identified between the two groups in the GM, ES, FIB_CLS, GM_CLS, or ES_CLS (P > .05). Interpretation of these results indicate that during a dynamic perturbation task individuals with FAI demonstrate longer fibularis muscle latencies on the injured side while no significant changes in the proximal muscle groups. Additionally, short and long latency reflex amplitude was significantly decreased in FAI individuals.     

Surface electromyograph activity of submental muscles during swallowing and expiratory muscle training tasks in Huntington’s disease patients

IntroductionHuntington’s disease (HD) patients have difficulty in swallowing, leading to aspiration pneumonia, which is a major cause of death. It seems possible that submental muscles that are crucial for preventing an escape of a bolus into the airway, are affected by HD, but no previous studies have investigated this.ObjectiveTo assess surface electromyograph (sEMG) activity of submental muscles during swallowing and expiratory muscle training (EMT) tasks in HD patients in comparison to healthy volunteers.MethodssEMG activities of submental muscles during saliva, water swallowing, EMT tasks performed at 25% and 75% of maximum expiratory pressure were recorded and normalised by the sEMG activity during an effortful swallow in 17 early to mid stage HD patients and 17 healthy volunteers.ResultssEMG activity was greater (p < 0.05) during EMT tasks than saliva and water swallowing, but was not significantly different between groups for saliva, water swallowing and EMT at 25%. HD patients had lower sEMG activity for EMT at 75% (p < 0.05).ConclusionDecreases in submental muscle activity were not evident in HD patients except during EMT at 75%. This suggests that relative submental muscle weakness is observed only during a high intensity task in early to mid stage HD patients.     

Neuromuscular and psychological influences on range of motion recovery in anterior cruciate ligament reconstruction patients

To identify distinguishing characteristics for knee surgery patients who experience a protracted recovery process, we sought to determine if there is an association between the neuromuscular stretch reflex and psychological factors of pain perception and anxiety on the range of motion (ROM) recovery rate of post-operative anterior cruciate ligament reconstruction (ACLR) rehabilitation patients. The ACLR participants were categorized into a slow recovery group (SRG: >6 weeks to recover 0–125° knee flexion [n = 10]) and a normal recovery group (NRG: <6 weeks to recovery 0–125° knee flexion [n = 12]). Control participants (n = 22) were age, gender and activity-level matched to the surgical participants. Neuromuscular testing consisted of sagittal plane video kinematics of the Wartenberg Pendulum Test for determining lower limb stiffness indices and electromyography-monitored patellar tendon tap reflex responses. Psychological and health status assessments consisted of the State–Trait Anxiety Inventory and SF-36? Health Survey. Data revealed that neuromuscular reflex profiles, lower limb stiffness indices, pain, anxiety and SF-36? indices of function were not significantly different between the two surgical groups (SRG and NRG). The surgical groups exhibited significantly greater pain (2.67 ± 2.27 SRG, 1.49 ± 1.15 NRG) than the control group (p ? .05). SF-36? indices were significantly lower for the surgical groups for total score (546.55 ± 94.70 SRG, 577.57 ± 125.58 NRG), function 69.00 ± 20.24 SRG, 67.08 ± 19.12 NRG), role physical (53.75 ± 22.85 SRG, 53.12 ± 23.15 NRG), social (76.24 ± 25.31 SRG, 65.62 ± 27.24 NRG), and emotional (82.49 ± 19.81 SRG, 81.38 ± 23.02 NRG) subscales (p ? .05). These results suggest that neuromuscular reflex responses, visual analogue scale (VAS) pain, and anxiety are not distinguishing factors for ROM recovery rate between the SRG and NRG. Decreased SF-36? indices, including pain as it influences function, though clinically relevant factors, were not statistically associated with post-operative ROM recovery rate.     

Role of vision and task complexity on soleus H-reflex gain

There exists extensive evidence supporting the presence of reflex modulation in humans during a variety of motor tasks. The soleus H-reflex has been shown to be modulated during static and dynamic balance conditions as well as during various motor tasks. The purpose of this study was to examine the effects of two different stance positions and visual conditions on soleus H-reflex gain in 15 apparently healthy adults (mean age = 30.27 ± 6.92 yrs). The soleus H-reflexes were examined in two experimental stance conditions: two-legged (stable) and one-leg (unstable), and two visual conditions: eyes open and eyes closed. To assess the reflex gain, subjects performed ten trials under each of the four conditions and a soleus H-reflex was elicited during the performance of each trial. For each condition the peak-to-peak amplitude of the H-reflex and the EMG activity 50 ms prior to the stimulus was recorded. Differences in the peak-to-peak amplitudes of the soleus H-reflex for the experimental conditions were compared with a 2 × 2 (Stance × Vision) repeated measures ANOVA. The level of significance was p < 0.05. Results demonstrated significant differences in reflex gain for both the vision (F_l,15 = 4.87, p < 0.05) and the stance condition (F_l,15 = 14.86, p < 0.05). Although both the stance condition and vision significantly affected the H-reflex gain, there was no interaction between these two variables (F_l,15 = 0.17). From these results, we conclude that H-reflex gain was decreased both as stance complexity increased and as visual inputs were removed. Consistent with previous reports, it may be speculated that changes in presynaptic inhibition to the soleus Ia fibers regulate these gain changes. We propose that vision and stability of stance affect soleus H-reflex gain, but do so without any interactive effects.     

Surface electromyography reveals males have a slower patellar reflex than females

In humans the cross sectional area of spinal motor neurons at L3 is larger in males than in females. Since these contribute to the control of the quadriceps femoris muscle group and are involved in the patellar reflex (PR), gender differences in the PR are expected. We have investigated this possibility using a group of 28 young subjects (14 male and 14 female) aged 20–22 years. The PR was quantified by the muscle compound action potential (MCAP) from the surface electromyogram (sEMG) of the vastus lateralis muscle. We found that the PR latency in females (17 ± 0.19 ms), was significantly (p < 0.001) faster than in males (21 ± 0.37 ms). This 4 ms difference in latency could not be ascribed to differences in stature or thigh length. In conclusion, for the age range tested females posses a significantly faster patellar reflex than males. We suggest that the slower PR latency of male subjects may arise in part from their larger α-motorneurons: such that longer integration times are required for the summation of postsynaptic excitation to be sufficient to excite α-motorneurons.     

Corticospinal responses of resistance-trained and un-trained males during dynamic muscle contractions

Little is known regarding the modulation and the plasticity of the neural pathway interconnecting elements of the central nervous system and skeletal muscle in resistant-trained individuals. The aim of the study was to compare corticospinal and spinal responses measured during dynamic muscle contractions of the tibialis anterior in resistance trained (RT) and un-trained (UT) males. Nine UT and 10 RT male volunteers reported to the laboratory 24 h following a familiarisation session. Motor evoked potentials (MEPs) and the cortical silent period were evoked using transcranial magnetic stimulation at a range of contraction intensities and was delivered as the ankle passed 90° during shortening and lengthening contractions. The Hoffmann reflex (H-reflex) and V-waves were evoked with peripheral nerve stimulation. Despite the RT group being significantly stronger during shortening (28%; P = 0.023: CI = 1.27–15.1 N m), lengthening (25%; P = 0.041: CI = 0.27–17.0 N m) and isometric muscle actions (20%; P = 0.041; CI = 0.77–14.9 N m), no differences between the groups existed for corticospinal or spinal variables. Lack of detectable differences between RT and UT individuals may be linked to minimal exposure to task specific, isolated high intensity resistance training of the TA muscle.     

Neural control of leg stiffness during hopping in boys and men

The purpose of the study was to investigate whether boys and men utilise different control strategies whilst hopping. Eleven boys (11–12 yr old) and ten men completed hopping at 1.5 Hz, 3.0 Hz and at their preferred frequency. A footswitch measured contact and flight times, from which leg stiffness was calculated. Simultaneously, surface electromyograms (EMGs) of selected lower limb muscles were recorded and quantified for each 30 ms period during the first 120 ms post-ground contact. At 1.5 Hz there were no differences between the groups in relative stiffness or muscle activity. At 3.0 Hz men had significantly shorter contact times (P = 0.013), longer flight times (P = 0.002), greater relative stiffness (P = 0.01) and significantly greater soleus (P = 0.012) and vastus lateralis (P < 0.001) activity during the initial 30 ms post-ground contact. At the preferred frequency men hopped significantly faster than the boys (P = 0.007), with greater leg stiffness (P < 0.01) and with more extensor activity in most time periods. Boys and men demonstrated similar control strategies when hopping at a slow frequency, but when hopping frequency increased men were able to better increase feedforward and reflex muscle activity to hop with greater relative stiffness.     

Temporal and spatial expression of the four Igf ligands and two Igf type 1 receptors in zebrafish during early embryonic development

The insulin-like growth factor (Igf) family is an evolutionarily conserved system essential for normal growth and development in vertebrates. Unlike mammals, four distinct Igf ligands (Igf1, Igf2a, Igf2b and Igf3) and two Igf type 1 receptors (Igf1ra and Igf1rb) are present in zebrafish. However, the localization of these multiple ligands and receptors especially the recently discovered igf3 during early development of zebrafish is poorly understood. In this study, detailed expression patterns of these components of the Igf system during embryogenesis of zebrafish were analyzed. It was found that igf1 is specifically expressed in the trigeminal ganglia region from 18 hpf to 72 hpf, while igf2a is restricted to the caudal regions of the notochord from 14 hpf to 18 hpf as well as in the midbrain, dorsal hind brain and otic vesicle at 24 hpf. On the other hand, igf2a is highly expressed in the midbrain and pharyngeal arch region at 48 hpf, followed by its appearance in the liver and brain at 72 hpf, while igf2b is restricted to the floor plate and hypochord from 12 hpf to 18 hpf, and strong expression is also detected in the midbrain and dorsal hind brain at 24 hpf. The teleost specific igf3 is highly expressed in the pharyngeal arch region before 24 hpf, but is then restricted to the sternohyoideus after 48 hpf. The receptor subtype igf1ra is ubiquitously expressed before 24 hpf but is confined to the brain at 72 hpf. However, igf1rb is widely expressed before 10 hpf, but is more confined to the brain region at 24 hpf and 72 hpf. This dynamic temporal-spatial expression during embryogenesis of zebrafish, together with the unique and overlapping expression patterns of the Igf ligands and receptors suggest the coordination of the divergent functions of the Igf system during early development in zebrafish.     

Photodynamic therapy inhibits cell adhesion without altering integrin expression

Adhesion is a primordial cell function that, among others, regulates inflammation, metastasis, and tissue repair. To understand how these events could be affected by photodynamic therapy (PDT), we studied the effects of PDT on human foreskin fibroblast (HFF) adhesion to bovine collagen type I, human vitronectin or fibronectin. PDT, using benzoporphyrin derivative monoacid ring A (verteporfin) as the photosensitizer, inhibited cell adhesion in a drug dose-dependent manner, with no significant difference among matrices. The drug dose that killed 90% of cells within 20 h post-treatment inhibited HFF adhesion by 55%–68%. However, 45 min following PDT, a time period corresponding to that of the adhesion assay, HFF membrane integrity remained unaltered. In addition, cell surface expression of integrins was not modified for at least 2 h following PDT. Western blots of cell lysates, using the anti-phosphotyrosine 4G10 monoclonal antibody, revealed that PDT prevented the adhesion-induced phosphorylation of 110–130 kDa proteins. Immunoblots of cell lysates immunoprecipitated with antibodies to focal adhesion kinase suggested that its phosphorylation was suppressed by PDT. These results demonstrate that PDT inhibits cell adhesion and affects integrin signalling without modifying cell membrane integrity or integrin expression.     

Loading and knee flexion after stroke: Less does not equal more

It is believed that force feedback can modulate lower extremity extensor activity during gait. The purpose of this research was to determine the role of limb loading on knee extensor excitability during the late stance/early swing phase of gait in persons post-stroke. Ten subjects with chronic hemiparesis post-stroke participated in (1) seated isolated quadriceps reflex testing with ankle loads of 0–0.4N m/kg and (2) gait analysis on a treadmill with 0%, 20% or 40% body weight support. Muscle reflex responses were recorded from vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) during seated testing. Knee kinematics and quadriceps activity during late stance/early swing phase of gait were compared across loading conditions. Although isolated loading of the ankle plantarflexors at 0.2 N m/kg reduced VM prolonged response (p = 0.04), loading did not alter any other measure of quadriceps excitability (all p > 0.08). During gait, the use of BWS did not influence knee kinematics (p = 0.18) or muscle activity (all p > 0.17) during late stance/early swing phase. This information suggests that load sensed at the ankle has minimal effect on the ipsilateral quadriceps of individuals post-stroke during late stance. It appears that adjusting limb loading during rehabilitation may not be an effective tool to address stiff-knee gait following stroke.     

Early liraglutide treatment is better in glucose control, β-cell function improvement and mass preservation in db/db mice

Glucagon-like peptide-1 (GLP-1) has been proved to have effects of anti-hyperglycemia and β-cell preservation. However, it is still unclear whether there are differences between early and late GLP-1 intervention in type 2 diabetes mellitus (T2DM). We divided the mice into 5 groups: early treated group (n = 7, 8-week old, fasting glucose > 10 mmol/l), late treated group (n = 7, 10-week old, fasting glucose > 20 mmol/l), early control group (n = 7), late control group (n = 7) and wild type group (n = 7). Treated group was injected with liraglutide (a GLP-1 analog) 300 μg/kg bid for 4 weeks, while control group was given saline at the same time. The results showed that compared with control group, food intake and body weight gain were reduced in both early and late treated group (p < 0.05), and there was no significance between the two treated groups. Early liraglutide intervention showed better improvements in glucose control, acute insulin response to glucose (AIRg) and disposition index (before vs. after treatment, AIRg 1.01 ± 0.53 vs. 2.98 ± 0.63, disposition index 10.81 ± 0.89 vs. 27.4 ± 2.15) than late intervention (AIRg 0.99 ± 0.02 vs. 1.41 ± 0.32, disposition index 3.47 ± 0.38 vs. 6.43 ± 1.62, p = 0.001). The histopathology of the pancreas showed the estimated β-cell mass (BCM) was increased more in early treated group than that in late one (0.03 vs. 0.01 g). Expressions of the proliferation related genes PDX-1, MafA and GLP-1 receptor (GLP-1R) in early treated group were 1.81, 2.57 and 1.59 times as much as that in late treated group. In conclusion, early liraglutide intervention was better in glucose control, β-cell function improvement and β-cell mass preservation.     

Acridin-3,6-dialkyldithiourea hydrochlorides as new photosensitizers for photodynamic therapy of mouse leukemia cells

Acridin-3,6-dialkyldithiourea hydrochlorides (AcrDTUs) have been evaluated as a new group of photosensitizers (PSs) for photodynamic antitumor therapy (PDT). Mouse leukemia cells L1210 were used for testing of AcrDTUs as the new PSs. The irradiation (UV-A light (365 nm), 1.05 J/cm²) increased cytotoxicity of all derivatives against L1210 cells more than ten times. The highest photocytotoxicity was found for propyl-AcrDTU with IC₅₀ = 0.48 ± 0.03 μM after 48 h incubation. A generation of the superoxide radical anion upon UV-A irradiation of propyl-AcrDTU was confirmed by in situ photochemical EPR experiments. To explain a mechanism of photocytotoxic action of AcrDTUs, an intracellular distribution of propyl-AcrDTU has been studied. It was found that AcrDTU in non-irradiated cells was not present in their nucleus but in the lysosomes and partly in the mitochondria, and sequestration of propyl-AcrDTU was dependent on pH in lysosomes. After irradiation, the cell death was induced by oxidative damage of lysosomal and mitochondrial membranes. Concerning the cell cycle, flow cytometry after PDT with propyl-AcrDTU showed a significant increase of the cells in the subG₀ phase. Observed signs of necrosis, apoptosis, and autophagy indicate that PDT/AcrDTU leads to multiple cell death types (caspase independent apoptosis, necrosis, and autophagy).     

Interlimb symmetry of dynamic knee joint stiffness and co-contraction is maintained in early stage knee osteoarthritis

Individuals with knee OA often exhibit greater co-contraction of antagonistic muscle groups surrounding the affected joint which may lead to increases in dynamic joint stiffness. These detrimental changes in the symptomatic limb may also exist in the contralateral limb, thus contributing to its risk of developing knee osteoarthritis. The purpose of this study is to investigate the interlimb symmetry of dynamic knee joint stiffness and muscular co-contraction in knee osteoarthritis.Muscular co-contraction and dynamic knee joint stiffness were assessed in 17 subjects with mild to moderate unilateral medial compartment knee osteoarthritis and 17 healthy control subjects while walking at a controlled speed (1.0 m/s). Paired and independent t-tests determined whether significant differences exist between groups (p < 0.05).There were no significant differences in dynamic joint stiffness or co-contraction between the OA symptomatic and OA contralateral group (p = 0.247, p = 0.874, respectively) or between the OA contralateral and healthy group (p = 0.635, p = 0.078, respectively). There was no significant difference in stiffness between the OA symptomatic and healthy group (p = 0.600); however, there was a slight trend toward enhanced co-contraction in the symptomatic knees compared to the healthy group (p = 0.051).Subjects with mild to moderate knee osteoarthritis maintain symmetric control strategies during gait.     

Development to the blastocyst stage of immature pig oocytes arrested before the metaphase-II stage and fertilized in vitro

In vitro fertilization (IVF) and embryonic development of mature and meiotically arrested porcine oocytes were compared in the present study. After in vitro maturation (IVM) of cumulus-oocyte complexes for 48 h, 75.4% of them extruded a visible polar body (PB). Most of the oocytes with a first polar body (PB+ group) were at the metaphase-II (M-II) stage (91.4%). Most of the oocytes without a visible polar body (PB− group) appeared to be arrested at the germinal vesicle (GV) (41.6%) and metaphase-I (M-I) (34.0%) stages. After IVF of oocytes (day of IVF = Day 0), there was no difference between PB⁺ and PB⁻ groups in rates of sperm penetration, mono-spermy, however oocyte activation rate after penetration was greater in the PB+ than in the PB− group (P < 0.05). On Day 2, there was no difference between rates of embryos cleaved at the 2–4 cell stages in PB+ and PB− groups (42.1 ± 48.8% and 33.6 ± 2.1%, respectively). On Day 4, the rate of PB+ embryos developing beyond the 4-cell stage was greater than that of PB− embryos (P < 0.05, 31.7 ± 3.9% and 14.1 ± 1.5%, respectively), and PB+ embryos had more cells than the PB− embryos (P < 0.05, 8.3 ± 0.4 and 6.0 ± 0.8 cells, respectively). On Day 6, a greater proportion of PB+ embryos developed to the blastocyst stage than did PB− embryos (P < 0.05, 34.6 ± 2.4% and 20.7 ± 2.8%, respectively). However, when the GV oocytes of the PB− group were not included in recalculations, there was no difference in blastocyst rates between M-I arrested and M-II oocytes (35.3 and 34.6%, respectively). The number of blastomere nuclei in embryos obtained from the PB+ group (52.0 ± 2.5) was greater than that from the PB− group (P < 0.05, 29.1 ± 2.8). The proportion of degenerated parts in the blastocysts, as determined by morphological appearance, was the same in the PB+ and PB− groups. Although the quality of PB+ embryos was enhanced as compared with that of the PB− group, the proportion of inner cell mass and trophectoderm cells in PB+ and PB− blastocysts did not differ (1:1.9 and 1:2.2, respectively). Chromosome analysis revealed that PB+ blastocysts had more diploidy (P < 0.05, 69.7%) than did PB− blastocysts (44.0%), whereas PB− blastocysts had more triploid cells (P < 0.05, 34.0%) than did PB+ oocytes (8.4%). These results indicate that pig oocytes arrested before the M-II stage (M-I oocytes) undergo cytoplasmic maturation during maturation culture and have the same ability to develop to blastocysts after IVF as M-II oocytes, but some of them resulted in degeneration or delayed development with poor embryo quality.     

Neuromuscular electrical stimulation attenuates thigh skeletal muscles atrophy but not trunk muscles after spinal cord injury

The current study examined the effects of 12 weeks of surface neuromuscular electrical stimulation (NMES) and ankle weights on the cross-sectional areas (CSAs) of three thigh [Gracilis (Gra), Sartorious (Sar) and Adductor (Add)] as well as two trunk [hip flexor (HF) and back extensor (BE)] muscle groups in men with spinal cord injury (SCI). Seven individuals with chronic motor complete SCI were randomly assigned into a resistance training + diet (RT + diet; n = 4) or diet control (n = 3) groups. The RT + diet group underwent twice weekly training with surface NMES and ankle weights for 12 weeks. Training composed of four sets of 10 repetitions of leg extension exercise while sitting in their wheelchairs. Both groups were asked to monitor their dietary intake. Magnetic resonance images were captured before and after 12 weeks of interventions. Gra muscle CSA showed no change before and after interventions. A significant interaction (P = 0.001) was noted between both groups as result of 9% increase and 10% decrease in the Gra muscle CSA of the RT + diet and diet groups, respectively. Sar muscle CSA increased [1.7 ± 0.4–2.5 ± 0.5 cm²; P = 0.029] in the RT + diet group with no change [2.9 ± 1.4–2.6 ± 1.3 cm²] in the diet group; with interaction noted between both groups (P = 0.002). Analysis of covariance indicated that Add muscle CSA was 38% greater in the RT + diet compared to the diet group (P = 0.025) after 12 weeks; a trend of interaction was also noted between both groups (P = 0.06). HF and BE muscle groups showed no apparent changes in CSA in both groups. The results suggested that surface NMES can delay the process of progressive skeletal muscle atrophy after chronic SCI. However, the effects are localized to the trained thigh muscles and do not extend to the proximal trunk muscles.     

The effect of glucagon-like peptide-2 on arterial blood flow and cardiac parameters

BackgroundGlucagon-like peptide-2 (GLP-2) is known to increase mesenteric blood flow. The aim of the study was to evaluate the effect of GLP-2 on blood flow in different vascular sites, and dynamic changes in cardiac parameters.Methods10 healthy volunteers were given 450 nmol subcutaneous (SC) GLP-2 or isotonic saline (5 subjects) in a single blinded manner. During the following 90 min, blood flow in the superior mesenteric artery (SMA), celiac artery (CA), renal artery (RA), common carotid artery (CCA) was measured using Doppler ultrasound (US), and cardiovascular variables were measured by impedance cardiography and finger plethysmography. Plasma GLP-2 was measured at times 0, 30 and 60 min.ResultsCompared to the placebo group, GLP-2 elicited a 27% decrease in the resistance index (RI) and a 269.4% increase in Time Averaged Maximal Velocity (TAMV) in the SMA (P < 0.01). CA, RA and CCA: There were no significant changes in RI or TAMV in the GLP-2 or placebo group, and no change in CA diameter.Cardiac parameters: GLP-2 increased cardiac output (CO), stroke volume (SV) and heart rate (HR) compared to baseline (respectively: 15.3, 4.81 and 8.2% (P < 0.001, P < 0.01 and P < 0.01)). The CO, SV and HR changes were not significantly different from the placebo group.Mean plasma GLP-2 serum levels in the placebo group at times 0, 30 and 60 min were 22.8, 23.4 and 23.2 pmol/l. In the GLP-2 group 20.3, 1273 and 1725 pmol/l.ConclusionSC GLP-2 increased SMA blood flow, as previously shown, but elicited no changes in other vascular sites. CO and HR increased significantly, presumably due to the increased mesenteric blood flow.     

Kinematic chain reactions on trunk and dynamic postural steadiness in subjects with recurrent low back pain

Although subjects with recurrent low back pain (LBP) demonstrate altered trunk control, the kinematic and kinetic responses of the trunk have not been carefully investigated. This study was conducted to compare the standing time, spine range of motion (ROM), and dynamic postural steadiness index (DPSI) based on visual condition between subjects with and without recurrent LBP during upright one leg standing. Sixty-three individuals participated in the study, including 34 control subjects and 29 subjects with recurrent LBP. The DPSI was a composite of the medio-lateral (MLSI), anterior-posterior (APSI), and vertical steadiness indices (VSI) on a force platform. The control group demonstrated longer standing time (s) during the eyes-open condition than the LBP group (26.82 ± 6.03 vs. 19.87 ± 9.36; t = 2.96, p = 0.01). Regarding spine ROM, visual condition was significantly different between groups (F = 7.09, p = 0.01) and demonstrated interactions with spine region and group (F = 5.53, p = 0.02). For the kinetic measures, there was a significant interaction between visual conditions and indices (F = 25.30, p = 0.001). In the LBP group, the DPSI was significantly correlated with the MLSI (r = 0.59, p = 0.002), APSI (r = 0.44, p = 0.03), and VSI (r = 0.98, p = 0.01) in the eyes-closed condition. Overall, the results of this study indicated that the LBP group decreased thorax and lumbar spine rotations during the eyes-closed condition. The LBP group also demonstrated positive correlations with the kinetic indices, enhancing dynamic postural steadiness in the eyes-closed condition in order to possibly avoid pain or further injury. This dynamic postural steadiness strategy is necessary to improve kinetic and kinematic chain reactions in the LBP group. This compensatory pattern supports the development of optimal postural correction strategies to prevent LBP recurrence and might represent a chain reaction to protect trunk control without visual input.     

Spectral analysis of EMG using intramuscular electrodes reveals non-linear fatigability characteristics in persons with chronic low back pain

Greater fatigability across lumbar extensors has been reported in persons with chronic low back pain (LBP), however, extensor atrophy tends to be local to the site of pain. Therefore, specific ultrasound guided local and remote intramuscular electromyographic recordings were undertaken during an isometric horizontal trunk hold in two carefully matched cohorts; persons with and without LBP. The test was performed to self-determined maximal hold time, and the control group held the horizontal position longer (P < 0.001). A power spectral analysis was performed to calculate the normalized median frequency (NMF) slope for both the first and last 30 s of the fatigue test due to the group difference in hold times. There were no significant group differences in NMF slope at the first 30 s of testing (P = 0.650). The NMF slope for the first and last 30 s was not different in healthy subjects (P = 0.688), but was different in persons with LBP, illustrated by shallowing of the slope at the last 30 s of the test (P = 0.008). A between muscle comparison in the LBP group showed greater non-linear behavior in the deep multifidus (painful region) in contrast to T10 longissimus thoracis (nonpainful region) (P = 0.013). Possible explanations for these findings are discussed.     

Cryotherapy and ankle bracing effects on peroneus longus response during sudden inversion

Cryotherapy and ankle bracing are often used in conjunction as a treatment for ankle injury. No studies have evaluated the combined effect of these treatments on reflex responses during inversion perturbation. This study examined the combined influence of ankle bracing and joint cooling on peroneus longus (PL) muscle response during ankle inversion. A 2 × 2 RM factorial design guided this study; the independent variables were: ankle brace condition (lace-up brace, control), and treatment (ice, control), and the dependent variables studied were PL stretch reflex latency (ms), and PL stretch reflex amplitude (% of max). Twenty-four healthy participants completed 5 trials of a sudden inversion perturbation to the ankle/foot complex under each ankle brace and cryotherapy treatment condition. No two-way interaction was observed between ankle brace and treatment conditions on PL latency (P = 0.283) and amplitude (P = 0.884). The ankle brace condition did not differ from control on PL latency and amplitude. Cooling the ankle joint did not alter PL latency or amplitude compared to the no-ice treatment. Ankle bracing combined with joint cooling does not have a deleterious effect on dynamic ankle joint stabilization during an inversion perturbation in normal subjects.