Effect of prior instructions on preprogrammed reactions of trunk muscles in individuals with and without chronic low back pain

The late component of the stretch reflex occurring in humans within a 40 to 120 msec interval following a loading perturbation is qualified as a preprogrammed muscle reaction (PPR). The PPR size can be significantly modulated with prior instructions. These modifications are significantly influenced by a number of factors, in particular by the presence of pain syndromes. The objective of our study was to compare the effect of prior instructions on the PPR amplitude in the trunk muscles in individuals with chronic low back pain (LBP) compared to healthy controls. LBP is a widespread syndrome, especially in athletes. Surface EMGs were recorded from superficial trunk muscles, rectus abdominis (RA) and erector spinae (ES), in athletes suffering from chronic LBP (n = 24) and asymptomatic (healthy) athletes (n = 25). Loading perturbations (induced by dropping a weight, application of 3 kg force, ≈ 30 N, to the outstretched hand from a 8 cm height) were introduced in standing at a known time with prior instructions to “let go” for the induced perturbation or to “resist” it. The root mean square (RMS) of the EMG amplitudes within the reaction duration were compared between the two groups. Statistically significant differences were obtained when the mean PPR EMG amplitudes were compared between the LBP and control groups for the above two task instructions; this was found for both examined muscles, RA and ES (P < 0.05). Therefore, individuals with chronic LBP exhibit poorly modulated PPR amplitudes according to prior task instructions. Changes in the networks controlling automatically regulated movements and excitability of the spinal pathways could be responsible for this specificityПізній компонент стретч-рефлексу, що розвивається у людей в інтервалі 40–120 мс після пертурбації (навантаження), кваліфікується як м’язова препрограмована реакція (ППР). Величина ППР може істотно модулюватися під дією попередніх інструкцій. На ці модифікації істотно впливають численні фактори, зокрема наявність больових синдромів. Ціллю нашого дослідження було порівняння амплітуд ППР м’язів тулуба в осіб, що страждали на біль у попереку (БП), та здорових контрольних тестованих. БП є виключно широко розповсюдженим синдромом, особливо у спортсменів. Ми відводили ЕМГ від поверхневих м’язів тулуба – rectus abdominis (RA) та erectror spinae (ES) – у спортсменів із синдромом хронічного БП (n = 24) та спортсменів без такого розладу (здорових, n = 25). Силові пертурбації (прикладання ваги 3 кгс до витягнутої руки з висоти 8 см) вводились у певний момент до тестованого в положенні стоячи з попередніми інструкціями «не опиратися» введеному навантаженню або «опиратися» йому. Порівнювалися значення RMS для амплітуд ЕМГ у межах реакції, що спостерігалася в двох групах. Було виявлено, що середні амплітуди ППР-ЕМГ у групах БП та контролю при двох вказаних вище попередніх інструкціях вірогідно відрізнялися; це було властиве для обох обстежених м’язів – RA та ES (P < 0.05). Таким чином, особи, що страждають на хронічний БП, демонструють обмежену модуляцію амплітуди ППР відповідно до попередніх інструкцій. Зміни в нейронних мережах, що контролюють автоматично регульовані рухи та збудливість спінальних шляхів, вірогідно є відповідальними за таку специфіку

Intersubband spin-density excitations in quantum wells with Rashba spin splitting

In inversion-asymmetric semiconductors, spin-orbit coupling induces a k-dependent spin splitting of valence and conduction bands, which is a well-known cause for spin decoherence in bulk and heterostructures. Manipulating nonequilibrium spin coherence in device applications thus requires understanding how valence and conduction band spin splitting affects carrier spin dynamics. This paper studies the relevance of this decoherence mechanism for collective intersubband spin-density excitations (SDEs) in quantum wells. A density-functional formalism for the linear spin-density matrix response is presented that describes SDEs in the conduction band of quantum wells with subbands that may be non-parabolic and spin-split due to bulk or structural inversion asymmetry (Rashba effect). As an example, we consider a 40 nm GaAs/AlGaAs quantum well, including Rashba spin splitting of the conduction subbands. We find a coupling and wavevector-dependent splitting of the longitudinal and transverse SDEs. However, decoherence of the SDEs is not determined by subband spin splitting, due to collective effects arising from dynamical exchange and correlation.Comment: 10 pages, 4 figure

Common variants near MC4R are associated with fat mass, weight and risk of obesity.

To identify common variants influencing body mass index (BMI), we analyzed genome-wide association data from 16,876 individuals of European descent. After previously reported variants in FTO, the strongest association signal (rs17782313, P = 2.9 x 10(-6)) mapped 188 kb downstream of MC4R (melanocortin-4 receptor), mutations of which are the leading cause of monogenic severe childhood-onset obesity. We confirmed the BMI association in 60,352 adults (per-allele effect = 0.05 Z-score units; P = 2.8 x 10(-15)) and 5,988 children aged 7-11 (0.13 Z-score units; P = 1.5 x 10(-8)). In case-control analyses (n = 10,583), the odds for severe childhood obesity reached 1.30 (P = 8.0 x 10(-11)). Furthermore, we observed overtransmission of the risk allele to obese offspring in 660 families (P (pedigree disequilibrium test average; PDT-avg) = 2.4 x 10(-4)). The SNP location and patterns of phenotypic associations are consistent with effects mediated through altered MC4R function. Our findings establish that common variants near MC4R influence fat mass, weight and obesity risk at the population level and reinforce the need for large-scale data integration to identify variants influencing continuous biomedical traits

Spondylarthropathies (including psoriatic arthritis): 244. Validity of Colour Doppler and Spectral Doppler Ultrasound of Sacroilicac Joints Againts Physical Examination as Gold Standard

Background: Sacroiliac joints (SJ) involvement is a distinctive and charasteristic feature of Spondyloarthritis (SpA) and x-ray is the test routinely used to make a diagnosis. However, x-ray reveals late structural damage but cannot detect active inflammation. The objective of this study was to assess the validity of Doppler ultrasound in SJ. Methods: Prospective blinded and controlled study of SJ, in which three populations were compared. We studied 106 consecutive cases, who were divided into three groups: a) 53 patients diagnosed with SpA who had inflammatory lumbar and gluteal pain assessed by a rheumatologist; b) 26 patients diagnosed with SpA who didn't have SJ tenderness and had normal physical examination; c) control group of 27 subjects (healthy subjetcs or with mechanical lumbar pain). All patients included that were diagnosed with SpA met almost the European Spondyloarthropathy Study Group (ESSG) classification criteria. Physical examination of the SJ included: sacral sulcus tenderness, iliac gapping, iliac compression, midline sacral thrust test, Gaenslen's test, and Patrick s test were used as gold standard. Both SJ were examined with Doppler ultrasound (General Electric Logiq 9, Wauwatosa WI, USA) fitted with a 9-14 Mhz lineal probe. The ultrasonographer was blinded to clinical data. Doppler in SJ was assessed as positive when both Doppler colour and resistance index (RI) < 0.75 within the SJ area were present. Statistical analysis was performed estimating sensitivity and specificity against gold standard. The Kappa correlation coefficient was used for reliability study. Results: 106 cases (53 female, 55 male; mean age 36 10 years) were studied. There were no statistical differences between groups related to age or sex. Physical examination of SJ was positive in 38 patients (59 sacroiliac joints). US detected Doppler signal within SJ in 37 patients (58 SJ): 33 of them were symptomatic SpA (52 SJ), one of them were asymptomatic SpA (1 SJ) and one was a healthy control (1 SJ). The accuracy of US when compared to clinical data as gold standard at subject level in the overall group was: sensitivity of 68.6% and specificity of 85.7%, positive predictive value of 70.5% and negative predictive value of 84.5%. A positive likelihood ratio of 4.8, a negative likelihood ratio of 0.36 and a kappa coefficient of 0.55 were achieved. Conclusions: Doppler US of SJ seems to be a valid method to detect active SJ inflammation. Disclosure statement: The authors have declared no conflicts of interes

Prevalence of Frailty in European Emergency Departments (FEED): an international flash mob study

Introduction Current emergency care systems are not optimized to respond to multiple and complex problems associated with frailty. Services may require reconfiguration to effectively deliver comprehensive frailty care, yet its prevalence and variation are poorly understood. This study primarily determined the prevalence of frailty among older people attending emergency care. Methods This cross-sectional study used a flash mob approach to collect observational European emergency care data over a 24-h period (04 July 2023). Sites were identified through the European Task Force for Geriatric Emergency Medicine collaboration and social media. Data were collected for all individuals aged 65 + who attended emergency care, and for all adults aged 18 + at a subset of sites. Variables included demographics, Clinical Frailty Scale (CFS), vital signs, and disposition. European and national frailty prevalence was determined with proportions with each CFS level and with dichotomized CFS 5 + (mild or more severe frailty). Results Sixty-two sites in fourteen European countries recruited five thousand seven hundred eighty-five individuals. 40% of 3479 older people had at least mild frailty, with countries ranging from 26 to 51%. They had median age 77 (IQR, 13) years and 53% were female. Across 22 sites observing all adult attenders, older people living with frailty comprised 14%. Conclusion 40% of older people using European emergency care had CFS 5 + . Frailty prevalence varied widely among European care systems. These differences likely reflected entrance selection and provide windows of opportunity for system configuration and workforce planning

Novel Loci for Adiponectin Levels and Their Influence on Type 2 Diabetes and Metabolic Traits : A Multi-Ethnic Meta-Analysis of 45,891 Individuals

J. Kaprio, S. Ripatti ja M.-L. Lokki työryhmien jäseniä.Peer reviewe

Effects of eye position on the vestibular evoked myogenic potential

Conclusion: The position of a subject's eyes during vestibular evoked myogenic potential (VEMP) recording significantly alters the magnitude of the response. This change is largely due to an alteration in the tonicity of the sternocleidomastoid muscle (SCM) caused by variations in the position of the eye. However, even if electromyographic (EMG) normalization is conducted effects of eye position remain.Objective: To determine if eye position has a significant effect on the magnitude of the VEMP.Subjects and methods: VEMPs were collected from 32 ears measured on 16 healthy subjects. The recordings were made unilaterally using the head turn method. The acoustic stimuli were 500 Hz air-conduction short tone bursts. VEMPs were measured in three recording conditions: (i) eyes in the same direction as head turn, (ii) eyes straight ahead, (iii) eyes in the opposite direction to head turn.Results: All 32 ears tested showed a VEMP response with eyes in all three positions. Repeated measures analysis of variance (RM-ANOVA) verified an overall significant effect of eye position (p&lt;0.001). Post hoc paired t tests revealed statistically significant differences between the eyes opposite and the other two conditions (p&lt;0.001). Normalization of the VEMP magnitude using pre-stimulus EMG reduced the effect; however, some variability remained