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.     

A compensation of angular displacements of the hip joints and lumbosacral spine between subjects with and without idiopathic low back pain during squatting

Low back pain (LBP) is one of the most common symptoms reported in adults. However, the contribution of postural control on the lumbar spine and hips during squatting has not been carefully investigated in individuals with LBP. The aim of this study was to compare three-dimensional kinematic changes of the lumbar spine and hips between subjects with and without idiopathic chronic LBP during squatting activities. In total, 30 subjects enrolled in the study (15 control subjects and 15 subjects with idiopathic chronic LBP). All participants were asked to perform squatting activities five times repeatedly while holding a load of 2 kg in a basket. The outcome measures included the Oswestry Disability Index (ODI) and kinematic angular displacement for the hips and lumbar spine. The LBP group demonstrated increased range of motion (ROM) in flexion of the dominant (T = ?2.14, p = 0.03) and non-dominant (T = ?2.11, p = 0.03) hips during squatting. The lumbar spine flexion ROM significantly decreased (T = 2.20, p = 0.03). The kinematic changes demonstrated interactions with region × group (F = 5.56, p = 0.02), plane × group (F = 4.36, p = 0.04), and region × plane (F = 2292.47, p = 0.001). The ODI level demonstrated significant interaction on combined effects of body region and plane (F = 4.91, p = 0.03). Therefore, the LBP group utilized a compensation strategy to increase hip flexion with a stiffened lumbar spine in the sagittal plane during squatting. This compensatory kinematic strategy could apply to clinical management used to enhance lumbar spine flexibility in subjects with idiopathic chronic LBP.     

Kinematic analyses of trunk stability in one leg standing for individuals with recurrent low back pain

This prospective study examined normalized stability differences based on dominance side and visual feedback. Subjects with low back pain (LBP) (n = 26; 9 men, 17 women) and without LBP (n = 28; 11 men, 17 women) participated in this study. All subjects were asked to maintain single leg standing balance with the contralateral hip flexed 90° for 25 s. The outcome measures included normalized holding duration and stability. The combined rotation (R_xyz) was also calculated to compare the upper and lower thorax and lumbar axes relative to the core spine axis. The holding duration was significantly different between groups (T = ?2.21, p = 0.03). The subjects without recurrent LBP (control group) demonstrated longer hold duration times (24.60 ± 4.2 s) than the subjects with recurrent LBP (21.2 ± 7.1 s). For the normalized hold duration, there was a significant difference between groups based on visual input (F = 7.13, p = 0.009). There was also a significant difference in standing stability based on visual input (F = 93.93, p = 0.0001) and trunk area (F = 101.51, p = 0.0001). In addition, the normalized stability was significantly different based on dominance and visual input (F = 11.28, p = 0.002). Therefore, trunk stability could prompt an uncoordinated bracing effect with poor proprioception from injury to passive structures or due to interference of pain during central processing of information in subjects with recurrent LBP.     

Altered preparatory pelvic control during the sit-to-stance-to-sit movement in people with non-specific low back pain

People with non-specific low back pain (LBP) show hampered performance of dynamic tasks such as sit-to-stance-to-sit movement. However, the underlying mechanisms remain obscure. Therefore, the aim of this study was to assess if proprioceptive impairments influence the performance of the sit-to-stance-to-sit movement.First, the proprioceptive steering of 20 healthy subjects and 106 persons with mild LBP was identified during standing using muscle vibration. Second, five sit-to-stance-to-sit repetitions on a stable support and on foam were performed as fast as possible. Total duration, phase duration, center of pressure (COP) displacement, pelvic and thoracic kinematics were analyzed.People with LBP used less lumbar proprioceptive afference for postural control compared to healthy people (P < 0.0001) and needed more time to perform the five repetitions in both postural conditions (P < 0.05). These time differences were determined in the stance and sit phases (transition phases), but not in the focal movement phases. Moreover, later onsets of anterior pelvic rotation initiation were recorded to start both movement sequences (P < 0.05) and to move from sit-to-stance on foam (P < 0.05).Decreased use of lumbar proprioceptive afference in people with LBP seemed to have a negative influence on the sit-to-stance-to-sit performance and more specifically on the transition phases which demand more control (i.e. sit and stance). Furthermore, slower onsets to initiate the pelvis rotation to move from sit-to-stance illustrate a decrease in pelvic preparatory movement in the LBP group.     

The eccentric,concentric strength relationship of the hamstring muscles in chronic low back pain

ObjectiveThe objective of this study was to measure hamstring muscle eccentric and concentric strength in individuals with and without low back pain (LBP). Two composite scores for the relative balance of eccentric to concentric strength at the different movement velocities were calculated (the DEC and SEC), to determine whether or not self perceived pain, disability, or fear avoidance measures were associated with hamstring strength characteristics.DesignCross-sectional repeated measures design.SettingUniversity laboratory.ParticipantsFifteen individuals with chronic LBP and 15 matched controls.Main outcome measuresIsokinetic eccentric and concentric strength at 30° s^?1 and 120° s^?1_. Composite scores (DEC and SEC) based on peak torque were calculated to evaluate the relationship between the different muscle actions across the test velocities. Self report measures included the Oswestry disability index, general health and well being, fear avoidance, and pain.ResultsEccentric/concentric strength ratio at 30° s^?1 was higher for the LBP group (F(1,58) = 4.81, p = 0.032). The SEC was also higher for the LBP (F(1,58) = 5.97, p = 0.018). Fear avoidance beliefs and mental well-being were significantly associated with the SEC only in the LBP group (adjusted r² = 0.26, (F(2,27) = 5.8, p = .008). For the control group both the DEC and SEC were associated with self report measures. Matched differences between groups’ for the SEC were best explained by fear avoidance beliefs about work (adjusted r² = 0.12, F(1,28) = 5.1, p = 0.03).ConclusionReduced concentric relative to eccentric strength is best identified by the SEC. The SEC was significantly associated with impaired self report measures of fear avoidance and mental well being in individuals with LBP. Differences between groups for the SEC were best explained by fear avoidance beliefs about work.     

Excited state properties of dinaphthyl ditelluride

Di-1-naphthyl ditelluride (Te₂naphthyl₂) is characterized by two low-energy excited states. The corresponding electronic transitions nTe → σ¹ Te–Te and nTe → π¹ naphthyl CT give rise to absorptions at λ_max = 403 and 311 nm, respectively. In solution nTe → σ¹ excitation leads to the cleavage of the Te–Te bond. In contrast to Te₂naphthyl₂ in the dissolved state the solid compound shows a luminescence (λ_max = 576 nm) which originates from nTe → π¹ naphthyl CT triplet.     

The role of trunk muscles in sitting balance control in people with low back pain

The purpose of this study was to examine the muscular activities and kinetics of the trunk during unstable sitting in healthy and LBP subjects. Thirty-one healthy subjects and twenty-three LBP subjects were recruited. They were sat on a custom-made chair mounted on a force plate. Each subject was asked to regain balance after the chair was tilted backward at 20°, and then released. The motions of the trunk and trunk muscle activity were examined. The internal muscle moment and power at the hip and lumbar spine joints were calculated using the force plate and motion data. No significant differences were found in muscle moment and power between healthy and LBP subjects (p > 0.05). The duration of contraction of various trunk muscles and co-contraction were significantly longer in the LBP subjects (p < 0.05) when compared to healthy subjects, and the reaction times of the muscles were also significantly reduced in LBP subjects (p < 0.05). LBP subjects altered their muscle strategies to maintain balance during unstable sitting, but these active mechanisms appear to be effective as trunk balance was not compromised and the internal moment pattern remained similar. The changes in muscle strategies may be the causes of LBP or the result of LBP with an attempt to protect the spine.     

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.     

The effect of heel lifts on trunk muscle activation during gait: A study of young healthy females

Heel lifts are a treatment option for low back pain (LBP), whilst high-heeled shoes have been linked to LBP development. This study evaluated the effects of in-shoe 20 mm high bilateral heel lifts on trunk muscle activity. Activity of the erector spinae (ErSp), internal oblique and external oblique muscles was evaluated using surface electromyography in 15 young (20.7 ± 0.9 years) healthy female participants. Measures were taken during overground gait, both immediately and following two days habituation to the heel lifts. Immediately following the addition of the heel lifts, levels of ErSp muscle activity in the 5% epoch following heel strike increased by 19.2% (p < 0.05). Following habituation, levels of ErSp muscle activity in the 5% epoch prior to heel strike increased by 24.1% (p < 0.05), and a 14 ms (p < 0.001) earlier onset of ErSp muscle activity prior to heel strike was observed. These results indicate the heel lifts altered muscle activity reactively around heel strike (i.e. greater activity after heel strike) immediately after application and proactively (i.e. earlier onsets and greater activity prior to heel strike) after short term habituation. When put in context of previous research on trunk muscle activity in LBP populations, these changes may be important considerations for the aetiology, treatment and prevention of LBP.     

Enhanced activity of immobilized pepsin nanoparticles coated on solid substrates compared to free pepsin

In the present work nanoparticles (NPs) of pepsin were generated in an aqueous solution using high-intensity ultrasound, and were subsequently immobilized on low-density polyethylene (PE) films, or on polycarbonate (PC) plates, or on microscope glass slides. The pepsin NPs coated on the solid surfaces have been characterized by HRSEM, TEM, FTIR, XPS and DLS. The amount of enzyme introduced on the substrates, the leaching properties, and the catalytic activity of the immobilized enzyme on the three surfaces are compared. Catalytic activities of pepsin deposited onto the three solid surfaces as well as free pepsin, without sonication, and free pepsin NPs were compared at various pH levels and temperatures using a hemoglobin assay. Compared to native pepsin, pepsin coated onto PE showed the best catalytic activity in all the examined parameters. Pepsin immobilized on glass exhibited better activity than the native enzyme, especially at high temperatures. Enzyme activity of pepsin immobilized on PC was no better than native enzyme activity at all temperatures at pH 2, and only over a narrow pH range at 37 °C was the activity improved over the native enzyme. A remarkable observation is that immobilized pepsin on all the surfaces was still active to some extent even at pH 7, while free pepsin was completely inactive. The kinetic parameters, K_m and V_max were also calculated and compared for all the samples. Relative to the free enzyme, pepsin coated PE showed the greatest improvement in kinetic parameters (K_m = 15 g/L, V_max = 719 U/mg versus K_m = 12.6 g/L and V_max = 787 U/mg, respectively), whereas pepsin coated on PC exhibited the most unfavorable kinetic parameters (K_m = 18 g/L, V_max = 685 U/mg). The values for the anchored enzyme-glass were K_m = 19 g/L, V_max = 763 U/mg.     

Changes in muscle activation patterns and subjective low back pain ratings during prolonged standing in response to an exercise intervention

BackgroundLow back pain (LBP) development has been associated with occupational standing. Increased hip and trunk muscle co-activation is considered to be predisposing for LBP development during standing in previously asymptomatic individuals. The purpose of this work was to investigate muscle activation and LBP responses to a prescribed exercise program. Pain-developing (PD) individuals were expected to have decreased LBP and muscle co-activation following exercise intervention.MethodsElectromyography (EMG) data were recorded from trunk and hip muscle groups during 2-h of standing. An increase of >10 mm on visual analog scale (VAS) during standing was threshold for PD categorization. Participants were assigned to progressive exercise program with weekly supervision or control (usual activity) for 4 weeks then re-tested.ResultsForty percent were categorized as PD on day 1, VAS = 24.2 (±4.0) mm. PD exercisers (PDEX) had lower VAS scores (8.93 ± 3.66 mm) than PD control (PDCON) (16.5 ± 6.3 mm) on day 2 (p = 0.007). Male PDEX had decreased gluteus medius co-activation levels (p < 0.05) on day 2.DiscussionThe exercise program proved beneficial in reducing LBP during standing. There were changes in muscle activation patterns previously associated with LBP. Predisposing factors for LBP during standing were shown to change positively with appropriate exercise intervention.     

Iodine binding property of a ternary complex consisting of starch,protein, and free fatty acids

A ternary complex consisting of amylose, whey protein, and free fatty acids (FFA) has been identified in our previous investigations, and its iodine binding properties were investigated. After reaction with iodine solution, an absorption peak (λ_max) at 620 nm was shown for pure amylose whereas the λ_max decreased to 510 nm when amylose was first complexed with FFA. Interestingly, a λ_max of 550 nm with an intermediate absorbance was observed for the ternary complex indicating its intermediate spectrophotometric property. Consistently, the amount of iodine bound by the ternary complex was between free amylose and typical amylose–FFA complex from potentiometric titration indicating the amylose–FFA complex within the ternary complex is less compact and more space is left for iodine binding. This in-between property of the ternary complex suggests it can be used as a molecular carrier to accommodate a forth component in addition to its functional lipids carrying capability in food product development.     

Sex-related differences in maximal rate of isometric torque development

Sex-differences in the maximum rate of torque development (dτ/dt_max) may be due to differences in maximum muscle strength, because higher torque values mathematically lead to higher values for the rate of change in torque. The rate of change in the isometric torque-time curve is often normalized to the isometric maximum voluntary contraction (MVC) to evaluate males and females on a relative scale. Normalization eliminates sex-differences in dτ/dt_max in the lower limbs because males and females are more comparable (i.e., differences between the sexes are relatively small) with respect to both muscle size and strength. However, normalization fails to result in parody in dτ/dt_max of the upper limb, leading to the idea that other factors may be involved. This study determined if sex-differences in dτ/dt_max in the upper limb can be attributed to differences in isometric MVC and/or a neural variable related to rate of increase in muscle activation (Q₃₀). Forty-six participants (23 males, 23 females) performed maximal isometric elbow flexion contractions, “as hard and as fast as possible”. Maximum torque (τ_max), dτ/dt_max, and the rate of increase in surface electromyographic (sEMG) activity (Q₃₀) were assessed. Muscle plus bone cross-sectional area (M + B CSA) of the upper arm was calculated to estimate differences in muscle size, only for comparative purposes. Maximum strength (55.5%) and muscle size (41.9%) of the elbow flexors in males were much greater than that of females (p < 0.05). There was a large difference (61.2%) between males and females with respect to dτ/dt_max that was reduced by statistical correction using an analysis of covariance (ANCOVA). The percent differences were reduced to 36.7% (p < 0.05) for τ_max and 54.4% (p < 0.05) for Q₃₀, but was nearly eliminated to 13.8% (p > 0.05) when both variables were used simultaneously as covariates. Since sex-differences in the upper limb dτ/dt_max persist, additional neural or biomechanical factors may be involved.     

Forming nanoparticles of α-amylase and embedding them into solid surfaces

In the current work nanoparticles (NPs) of α-amylase were generated in an aqueous solution using high-intensity ultrasound, and were subsequently immobilized on polyethylene (PE) films, or polycarbonate (PC) plates, or on microscope glass slides. The α-amylase NPs coated on the solid surfaces have been characterized by ESEM, TEM, FTIR, XPS and AFM. The substrates immobilized with α-amylase were used for hydrolyzing soluble potato starch to maltose. The amount of enzyme introduced in the substrates, leaching properties, and the catalytic activity of the immobilized enzyme were compared. The catalytic activity of the amylase deposited on the three solid surfaces was compared to that of the same amount of free enzyme at different pHs and temperatures. α-Amylase coated on PE showed the best catalytic activity in all the examined parameters when compared to native amylase, especially at high temperatures. When immobilized on glass, α-amylase showed better activity than the native enzyme over all pH and temperature values studied. However, the immobilization on PC did not improve the enzyme activity at any pH and any temperature compared to the free amylase. The kinetic parameters, K_m and V_max were also calculated. The amylase coated PE showed the most favorable kinetic parameters (K_m = 5 g L⁻¹ and V_max = 5E−07 mol mL⁻¹ min⁻¹). In contrast, the anchored enzyme-PC exhibited unfavorable kinetic parameters (K_m = 16 g L⁻¹, V_max = 4.2E−07 mol mL⁻¹ min⁻¹). The corresponding values for amylase-glass were K_m = 7 g L⁻¹, V_max = 1.8E−07 mol mL⁻¹ min⁻¹, relative to those obtained for the free enzyme (K_m = 6.6 g L⁻¹, V_max = 3.3E−07 mol mL⁻¹ min⁻¹).     

Standardized activities of daily living in presence of sub-acute low-back pain: A pilot study

The aim of this pilot study was to investigate how sub-acute low-back pain (LBP) patients differed with respect to control in movements and muscle activation during standardized tasks representing daily living activities, and explore relationships between cognition and measured motor performance. Linear and nonlinear parameters were computed from kinetics, kinematics and muscle activity recorded for 12 sub-acute patients and 12 healthy matched controls during trunk flexion, sit-to-stand from a chair and lifting a box. Cognitive variables were collected to explore relationships with biomechanical parameters. For trunk flexion, left external abdominal oblique muscle activity level was lower for patients compared with controls (p < 0.05), whereas sample entropy (complexity) was higher (p < 0.05). Normalized mutual information was lower for patients compared with controls for left and right erector spinae (p < 0.05). Level of activity of left external abdominal oblique correlated negatively with cognitive ignoring and positively with catastrophizing (p ? 0.05), and catastrophizing also correlated positively with functional connectivity of abdominal muscles (p < 0.05). Signs of reorganization in muscle activation pointed towards different synergistic actions in trunk muscles in sub-acute LBP patients compared with controls. The interplay with maladaptive cognition suggested that in the subacute stage of LBP, both biomechanical and cognitive factors should be taken into account.     

The use of intermittent trunk flexion to alleviate low back pain during prolonged standing

The current study examined of the effect of intermittent, short-term periods of full trunk flexion on the development of low back pain (LBP) during two hours of standing. Sixteen participants completed two 2-h standing protocols, separated by one week. On one day, participants stood statically for 2 h (control day); on the other day participants bent forward to full spine flexion (termed flexion trials) to elicit the flexion relaxation (FR) phenomenon for 5 s every 15 min (experimental day). The order of the control and experimental day was randomized. During both protocols, participants reported LBP using a 100 mm visual analogue scale every 15 min. During the flexion trials, lumbar spine posture, erector spinae and gluteus medius muscle activation was monitored. Ultimately, intermittent trunk flexion reduced LBP by 36% (10 mm) at the end of a 2-h period of standing. Further, erector spinae and gluteus medius muscle quietening during FR was observed in 91% and 65% of the flexion trials respectively, indicating that periods of rest did occurred possibly contributing to the reduction in LBP observed. Since flexion periods do not require any aids, they can be performed in most workplaces thereby increasing applicability.     

Novel oxazolinyl derivatives of pregna-5,17(20)-diene as 17α-hydroxylase/17,20-lyase (CYP17A1) inhibitors

New oxazolinyl derivatives of [17(20)E]-pregna-5,17(20)-diene: 2′-{[(E)-3β-hydroxyandrost-5-en-17-ylidene]methyl}-4′,5′-dihydro-1′,3′-oxazole 1 and 2′-{[(E)-3β-hydroxyandrost-5-en-17-ylidene]methyl}-4′,4′-dimethyl-4′,5′-dihydro-1′,3′-oxazole 2 were evaluated as potential CYP17A1 inhibitors in comparison with 17-(pyridin-3-yl)androsta-5,16-dien-3β-ol 3 (abiraterone). Differential absorption spectra of human recombinant CYP17A1 in the presence of compound 1 (λ_max = 422 nm, λ_min = 386 nm) and compound 2 (λ_max = 416 nm) indicated significant differences in enzyme/inhibitors complexes. CYP17A1 activity was measured using electrochemical methods. Inhibitory activity of compound 1 was comparable with abiraterone 3 (IC₅₀ = 0.9 ± 0.1 μM, and IC₅₀ = 1.3 ± 0.1 μM, for compounds 1 and 3, respectively), while compound 2 was found to be weaker inhibitor (IC₅₀ = 13 ± 1 μM). Docking of aforementioned compounds to CYP17A1 revealed that steroid fragments of compound 1 and abiraterone 3 occupied close positions; oxazoline cycle of compound 1 was coordinated with heme iron similarly to pyridine cycle of abiraterone 3. Configuration of substituents at 17(20) double bond in preferred docked position corresponded to Z-isomers of compounds 1 and 2. Presence of 4′-substituents in oxazoline ring of compound 2 prevents coordination of oxazoline nitrogen with heme iron and worsens its docking score in comparison with compound 1. These data indicate that oxazolinyl derivative of [17(20)E]-pregna-5,17(20)-diene 1 (rather than 4′,4′-dimethyl derivative 2) may be considered as potential CYP17A1 inhibitor and template for development of new compounds affecting growth and proliferation of prostate cancer cells.     

3-(Arylsulfonyl)-1-(azacyclyl)-1H-indoles are 5-HT6 receptor modulators

Novel 3-(arylsulfonyl)-1-(azacyclyl)-1H-indoles 6 were synthesized as potential 5-HT₆ receptor ligands, based on constraining a basic side chain as either a piperidine or a pyrrolidine. Many of these compounds had good 5-HT₆ binding affinity with K_i values <10 nM. Depending on substitution, both agonists (e.g., 6o: EC₅₀ = 60 nM, E_max = 70%) and antagonists (6y: IC₅₀ = 17 nM, I_max = 86%) were identified in a 5-HT₆ adenylyl cyclase assay.