Trunk postural control during unstable sitting among individuals with and without low back pain: A systematic review with an individual participant data meta-analysis.

INTRODUCTION: Sitting on an unstable surface is a common paradigm to investigate trunk postural control among individuals with low back pain (LBP), by minimizing the influence lower extremities on balance control. Outcomes of many small studies are inconsistent (e.g., some find differences between groups while others do not), potentially due to confounding factors such as age, sex, body mass index [BMI], or clinical presentations. We conducted a systematic review with an individual participant data (IPD) meta-analysis to investigate whether trunk postural control differs between those with and without LBP, and whether the difference between groups is impacted by vision and potential confounding factors. METHODS: We completed this review according to PRISMA-IPD guidelines. The literature was screened (up to 7th September 2023) from five electronic databases: MEDLINE, CINAHL, Embase, Scopus, and Web of Science Core Collection. Outcome measures were extracted that describe unstable seat movements, specifically centre of pressure or seat angle. Our main analyses included: 1) a two-stage IPD meta-analysis to assess the difference between groups and their interaction with age, sex, BMI, and vision on trunk postural control; 2) and a two-stage IPD meta-regression to determine the effects of LBP clinical features (pain intensity, disability, pain catastrophizing, and fear-avoidance beliefs) on trunk postural control. RESULTS: Forty studies (1,821 participants) were included for the descriptive analysis and 24 studies (1,050 participants) were included for the IPD analysis. IPD meta-analyses revealed three main findings: (a) trunk postural control was worse (higher root mean square displacement [RMSdispl], range, and long-term diffusion; lower mean power frequency) among individuals with than without LBP; (b) trunk postural control deteriorated more (higher RMSdispl, short- and long-term diffusion) among individuals with than without LBP when vision was removed; and (c) older age and higher BMI had greater adverse impacts on trunk postural control (higher short-term diffusion; longer time and distance coordinates of the critical point) among individuals with than without LBP. IPD meta-regressions indicated no associations between the limited LBP clinical features that could be considered and trunk postural control. CONCLUSION: Trunk postural control appears to be inferior among individuals with LBP, which was indicated by increased seat movements and some evidence of trunk stiffening. These findings are likely explained by delayed or less accurate corrective responses. SYSTEMATIC REVIEW REGISTRATION: This review has been registered in PROSPERO (registration number: CRD42021124658).

Evacuation solutions for individuals with functional limitations in the built environment: a scoping review protocol.

BACKGROUND: Whether due to aging, disability, injury, or other circumstances, an increasing number of Canadians experience functional limitations that reduce their ability to participate in activities of daily life. While the built environment has become increasingly accessible, existing Canadian evacuation guidelines lack comprehensive strategies for evacuating individuals with functional limitations from buildings during emergencies. To inform guideline revisions, a map of existing solutions for evacuating such individuals is required. Therefore, this scoping review aims to provide an account of solutions that have been reported to safely evacuate individuals with functional limitations from the built environment. METHODS: We will conduct a scoping review using the Arksey and O'Malley methodological framework. To identify potentially relevant studies, comprehensive searches (from January 2002 onwards) of the CINAHL, Ei Compendex, Inspec, Embase, MEDLINE, KCI, RSCI, SciELO CI, Web of Science Collection, and Scopus databases will be performed. Using a set of inclusion and exclusion criteria, two reviewers will independently (1) classify identified studies as relevant, irrelevant, or maybe relevant by evaluating their titles and abstracts and (2) classify the relevant and maybe relevant studies as included or excluded by evaluating their full-text. From each included study, data on publication information, study purpose, methodological details, evacuation information, and outcomes will be extracted using a set of data extraction items. We will present a numerical summary of the key characteristics of the included studies. For each evacuation activity, reported evacuation solutions will be summarized, and citations provided for functional limitations that are targeted by a given evacuation solution. To inform Canadian evacuation guideline revisions, we will tabulate evacuation activities common to different types of buildings and emergencies. DISCUSSION: To our knowledge, this will be the first scoping review to identify the state and use of solutions for evacuating individuals with functional limitations from the built environment. Identifying solutions that enable all individuals to safely evacuate from different types of buildings will allow us to inform recommendations for the revision of evacuation guidelines in Canada and other jurisdictions. The findings of this scoping review will be published in a peer-reviewed journal, presented at relevant conferences, and made publicly available on the internet. SYSTEMATIC REVIEW REGISTRATION: Open Science Framework: osf.io/jefgy.

Transcutaneous spinal cord stimulation improves postural stability in individuals with multiple sclerosis.

BACKGROUND: Widespread demyelination in the central nervous system can lead to progressive sensorimotor impairments following multiple sclerosis, with compromised postural stability during standing being a common consequence. As such, clinical strategies are needed to improve postural stability following multiple sclerosis. The objective of this study was therefore to investigate the effect of non-invasive transcutaneous spinal stimulation on postural stability during upright standing in individuals with multiple sclerosis. METHODS: Center of pressure displacement and electromyograms from the soleus and tibialis anterior were recorded in seven individuals with multiple sclerosis during standing without and with transcutaneous spinal stimulation. Center of pressure and muscle activity measures were calculated and compared between no stimulation and transcutaneous spinal stimulation conditions. The relationship between the center of pressure displacement and electromyograms was quantified using cross-correlation analysis. RESULTS: For transcutaneous spinal stimulation, postural stability was significantly improved during standing with eyes closed: the time- and frequency-domain measures obtained from the anterior-posterior center of pressure fluctuation decreased and increased, respectively, and the tibialis anterior activity was lower compared to no stimulation. Conversely, no differences were found between no stimulation and transcutaneous spinal stimulation when standing with eyes open. CONCLUSION: Following multiple sclerosis, transcutaneous spinal stimulation improved postural stability during standing with eyes closed, presumably by catalyzing proprioceptive function. Future work should confirm underlying mechanisms and explore the clinical value of transcutaneous spinal stimulation for individuals with multiple sclerosis.

Spatial and temporal relation of kinematics and muscle activity during unstable sitting.

Recent work suggests that kinematics-based electrical stimulation may restore dynamic trunk stability following spinal cord injury. However, to ensure fatigue-resistant control, knowledge of the relation between body motion and the activity of relevant muscles during non-impaired, unstable sitting may be beneficial. Therefore, our objective was to quantify the spatial and temporal relationships between (1) characteristic angular kinematics (i.e., the kinematics characterizing trunk stabilization) and (2) trunk and upper leg muscle activity in unstable sitting as elicited via a wobble board. Wobble board motion and bilateral electromyograms from fourteen trunk and upper leg muscles were recorded in fifteen non-disabled participants (i.e., individuals with no history of neurological or musculoskeletal impairments or pain, gait or balance difficulties, or use of a walking aid) sitting on a wobble board. The relationship between wobble board tilt and the electromyograms was quantified using cross-correlation analysis. During unstable sitting, the trunk was stabilized through direction-specific activation of the trunk and upper leg muscles, preceding wobble board displacement by 110-230 ms. Direction-specific activation implies the presence of active neural control, while preceding activation may be needed to account for known torque generation time delays. Furthermore, the specific muscles activated for each direction of wobble board displacement suggest the use of stiffness control in the anterior-posterior, but not medial-lateral direction. Future work will use the gained insights in defining the muscle stimulation patterns of kinematics-based neuroprostheses that can restore trunk stability following impairment.

A kinematics recommendation for trunk stability and control assessments during unstable sitting.

Trunk control has been commonly studied via an unstable sitting paradigm, with the majority of analyses using angular kinematics-based, posturographic measures. However, considerable variability in the choice of kinematics exists. Furthermore, the kinematics capturing the completion of this task are unknown. The purpose of this study was to characterize the kinematics in unstable sitting by quantifying and comparing the angular motion of the base of support, pelvis, and trunk as elicited via a commonly used wobble board (WB) paradigm. WB, pelvis, and trunk motion was recorded in fifteen non-disabled participants sitting on a wobble board. Posturographic measures were calculated and compared between corresponding WB and pelvis, and between WB and trunk angles. The trunk was stabilized through relatively large WB motion, with the trunk adopting a quasi-static pose. For all measures, angles, and conditions, the WB measure values were significantly larger than their corresponding pelvis or trunk values. Our findings demonstrate that the WB-human system is stabilized by regulating WB motion. Future work utilizing an unstable sitting surface and kinematics-based analyses to investigate trunk control should include the analysis of base of support kinematics.

Legalized Cannabis in Colorado Emergency Departments: A Cautionary Review of Negative Health and Safety Effects.

Cannabis legalization has led to significant health consequences, particularly to patients in emergency departments and hospitals in Colorado. The most concerning include psychosis, suicide, and other substance abuse. Deleterious effects on the brain include decrements in complex decision-making, which may not be reversible with abstinence. Increases in fatal motor vehicle collisions, adverse effects on cardiovascular and pulmonary systems, inadvertent pediatric exposures, cannabis contaminants exposing users to infectious agents, heavy metals, and pesticides, and hash-oil burn injuries in preparation of drug concentrates have been documented. Cannabis dispensary workers ("budtenders") without medical training are giving medical advice that may be harmful to patients. Cannabis research may offer novel treatment of seizures, spasticity from multiple sclerosis, nausea and vomiting from chemotherapy, chronic pain, improvements in cardiovascular outcomes, and sleep disorders. Progress has been slow due to absent standards for chemical composition of cannabis products and limitations on research imposed by federal classification of cannabis as illegal. Given these factors and the Colorado experience, other states should carefully evaluate whether and how to decriminalize or legalize non-medical cannabis use.

A method to estimate inertial properties and force plate inertial components for instrumented platforms.

Kinetic data acquired from force plates embedded in moving platforms naturally contain artifacts due to platform acceleration, called force plate inertial components. While they can be estimated and removed from the measured signals, the system's inertial properties need to be known. Our objective was to: (1) develop a method for estimating the inertial properties and force plate inertial components for any instrumented platform; (2) estimate the inertial properties specifically for the Computer-Assisted Rehabilitation Environment (CAREN); and (3) validate the estimates with new experimental data. Unloaded ramp-and-hold perturbations (for estimation) and unloaded random perturbations (for validation) were executed to obtain the force, moment, and motion of the CAREN platform. Inertial properties were estimated by minimizing the error between the measured and computed inertial forces and moments. Obtained estimates were validated by calculating the coefficient of determination (R2) between the measured and computed forces or moments when keeping the inertial properties fixed. The estimates of the CAREN's inertial properties exhibited low variability across trials, and R2 for the validation trials was 0.90 ± 0.08 (mean ± standard deviation). The developed method can be used for removing inertial components from force plate signals, yielding reliable estimates of ground reactions in dynamic biomechanical research and clinical assessments.

Comparison of Transesophageal and Transthoracic Echocardiographic Measurements of Mechanism and Severity of Mitral Regurgitation in Ischemic Cardiomyopathy (from the Surgical Treatment of Ischemic Heart Failure Trial).

Mitral regurgitation (MR) is common in ischemic heart disease and contributes to symptoms and mortality. This report compares the results of baseline transesophageal echocardiography (TEE) and transthoracic echocardiography (TTE) imaging of the mechanism and severity of functional MR in patients with ischemic cardiomyopathy in the Surgical Treatment for Ischemic Heart Failure (STICH) trial. Independent core laboratories measured both TTE and TEE images on 196 STICH participants. Common measurements to both models included MR grade, mitral valve tenting height and tenting area, and mitral annular diameter. For each parameter, correlations were assessed using Spearman rank correlation coefficients. A modest correlation was present between TEE and TTE for overall MR grade (n = 176, r = 0.52). For mechanism of MR, modest correlations were present for long-axis tenting height (n = 152, r = 0.35), tenting area (n = 128, r = 0.27), and long-axis mitral annulus diameter (n = 123, r = 0.41). For each measurement, there was significant scatter. Potential explanations for the scatter include different orientation of the imaging planes between TEE and TTE, a mean temporal delay of 6 days between TEE and TTE, and statistically significant differences in heart rate and blood pressure and weight between studies. In conclusion, TEE and TTE measurements of MR mechanism and severity correlate only modestly with enough scatter in the data that they are not interchangeable.

Successful ß cells islet regeneration in streptozotocin-induced diabetic baboons using ultrasound-targeted microbubble gene therapy with cyclinD2/CDK4/GLP1.

Both major forms of diabetes mellitus (DM) involve ß-cell destruction and dysfunction. New treatment strategies have focused on replenishing the deficiency of ß-cell mass common to both major forms of diabetes by islet transplantation or ß-cell regeneration. The pancreas, not the liver, is the ideal organ for islet regeneration, because it is the natural milieu for islets. Since islet mass is known to increase during obesity and pregnancy, the concept of stimulating pancreatic islet regeneration in vivo is both rational and physiologic. This paper proposes a novel approach in which non-viral gene therapy is targeted to pancreatic islets using ultrasound targeted microbubble destruction (UTMD) in a non-human primate model (NHP), the baboon. Treated baboons received a gene cocktail comprised of cyclinD2, CDK, and GLP1, which in rats results in robust and durable islet regeneration with normalization of blood glucose, insulin, and C-peptide levels. We were able to generate important preliminary data indicating that gene therapy by UTMD can achieve in vivo normalization of the intravenous (IV) glucose tolerance test (IVGTT) curves in STZ hyperglycemic-induced conscious tethered baboons. Immunohistochemistry clearly demonstrated evidence of islet regeneration and restoration of ß-cell mass.

Anomalous cord from the raphe of a congenitally bicuspid aortic valve to the aortic wall producing either acute or chronic aortic regurgitation.

OBJECTIVES: This report calls attention to an unappreciated cause of both acute and chronic aortic regurgitation (AR). BACKGROUND: Although stenosis develops in most patients with a congenitally bicuspid aortic valve (BAV), in others with this anomaly, pure AR (no element of stenosis) develops, some in the absence of infection or other clear etiology. METHODS: We describe 5 men who underwent aortic valve replacement for pure AR associated with a BAV containing an anomalous cord attaching the raphe of the conjoined cusp near its free margin to the wall of the ascending aorta cephalad to the sinotubular junction. RESULTS: Three of these 5 patients had a history of progressive dyspnea, and the anomalous cord, which was intact at operation, appeared to cause chronic AR by preventing proper coaptation of the 2 aortic valve cusps. The other 2 patients heard a "pop" during physical exertion and immediately became dyspneic, and at operation, the anomalous cord was found to have ruptured. Prolapse of the conjoined aortic valve cusp toward the left ventricular cavity resulted in severe acute AR. CONCLUSIONS: This variant of the purely regurgitant BAV may cause either chronic AR (when the anomalous cord does not rupture) or acute severe AR (when the cord ruptures).

Vehicle-mounted high-power microwave systems and health risk communication in a deployed environment.

Vehicle-mounted high-power microwave systems have been developed to counter the improvised explosive device threat in southwest Asia. Many service members only vaguely comprehend the nature of these devices and the nonionizing radio frequency (RF) radiation they emit. Misconceptions about the health effects of RF radiation have the potential to produce unnecessary anxiety. We report an incident in which concern for exposure to radiation from a high-power microwave device thought to be malfunctioning led to an extensive field investigation, multiple evaluations by clinicians in theater, and subsequent referrals to an Occupational Health clinic upon return from deployment. When acute exposure to RF does occur, the effects are thermally mediated and immediately perceptible--limiting the possibility of injury. Unlike ionizing radiation, RF radiation is not known to cause cancer and the adverse health effects are not cumulative. Medical officers counseling service members concerned about potential RF radiation exposure should apply established principles of risk communication, attend to real and perceived risks, and enlist the assistance of technical experts to properly characterize an exposure when appropriate.

Echocardiographic findings in professional hockey players.

Tissue Doppler imaging was used to evaluate the physiological and morphological response in athletes whose cardiac system must not only adapt to intense cardiovascular demands but also support sudden, transient changes in cardiac output. A total of 45 professional hockey players with a mean age of 24 years underwent a baseline transthoracic echocardiographic protocol after a typical morning workout; 12 healthy age- and gender-matched controls were evaluated as a means of comparison. The athletes in this study possessed larger left ventricular diastolic and systolic dimensions than the control group (5.5 ± 0.4 vs 4.9 ± 0.4 cm and 3.9 ± 0.4 vs 3.3 ± 0.4 cm, P < 0.0001). The increase in athletes' septal and posterior wall thickness was not substantial, nor was there a significant difference in left ventricular ejection fraction. The athletes demonstrated consistently larger left ventricular end-diastolic volume (196 ± 34 vs 136 ± 23 mL, P < 0.001) and end-systolic volume (87 ± 20 vs 57 ± 12 mL, P < 0.0001). They also had lower annular septal and lateral early diastolic and systolic tissue Doppler velocities compared with the control group. Thus, characteristic myocardial changes previously reported in elite athletes were also represented in professional hockey players. The lower left ventricular tissue Doppler velocities was a relatively unique finding and probably a consequence of lower postexertion preload levels compared with controls who were measured at rest.

Screening phosphatidylcholine biomarkers in mouse liver extracts from a hypercholesterolemia study using ESI-MS and chemometrics.

When fed a high-fat, high-cholesterol diet (HFD), homozygous LDL receptor knockout mice exhibit extremely high levels of plasma cholesterol that are expected to influence liver metabolism. One step in the investigation of potential hepatic alterations was the analysis of organic extracts of livers from these and control mice by electrospray mass spectrometry (ESI-MS). Chemometrics (bioinformatics) analysis shows that the sample spectra cluster into two groups: one from mice with plasma cholesterol levels in excess of 900 mg dL(-1) and one from animals with cholesterol levels of 60-250 mg dL(-1). The loadings plot of the first PC in the principal-components analysis (PCA) reveals the chemical basis for clustering, i.e., biomarkers present at different concentrations in the different groups. The exact masses of the key peaks in this loadings plot indicate these species are phosphatidylcholines (PtdChos). This assignment is confirmed by tandem MS. Partial least-squares (PLS) with variable selection shows that the spectra are well correlated with plasma total cholesterol, HDL cholesterol, and triglyceride (TG) levels.

The Short-Term Effect of Whole Body Vibration Training on Sprint Start Performance in Collegiate Athletes.

Whole body vibration (WBV) is characterized by a vibratory stimulus emitted throughout the body through the use of a vibrating platform on which the subject stands. Studies have shown over 30% increases in maximal explosive strength such as maximal speed biceps curl as well as increases in maximum dynamic force such as maximal sitting bench pull as the result of vibration. The purpose of this study was to investigate the effects of short term whole-body vibration on sprint starts among collegiate track athletes. On the first day eleven subjects were randomly assigned to either a non-vibration or vibration group for initial testing. The vibration group used whole body vibration along with their normal warm-up routine while the non-vibration group did not. Force measurements were taken where the starting blocks were placed using a force plate embedded under the track surface following the warm up. One week later the groups alternated. The results were then compared between vibration and non-vibration groups for individual athletes. The vibration protocol occurred for 60 s at 26 Hz with an amplitude of 4mm on a Galileo 2000 platform. Repeated measures analysis of the variance showed peak resultant force was 6% greater when the vibration platform was utilized prior to the start (p=0.013). Further research is needed to determine whether any meaningful differences exist in sprint start velocity as a result of WBV. There were no observed differences in the 30m sprint times.

The heaviest known operatively-excised aortic valve.

A 60-year-old man whose operatively excised stenotic and regurgitant aortic valve weighed nearly 15 g, approximately 30 times the normal weight in an adult, is described. To the investigators' knowledge, this is the heaviest aortic valve ever encountered in a human being.

Clinical application of harmonic power Doppler imaging in the assessment of myocardial perfusion by contrast echocardiography.

Myocardial contrast echocardiography has moved from the research laboratory to clinical echocardiography. As with any emerging technology, background information and understanding the process of image acquisition will help to integrate the technology into everyday practice. Harmonic power Doppler imaging (HPDI) is a high-power, triggered imaging modality used to assess myocardial perfusion. Contrast agents used in echocardiography provide microvascular tracers that enable HPDI to accurately visualize myocardial blood flow. This article aims to provide direction in the clinical performance of myocardial contrast echocardiography by providing background in the theory and physics of HPDI and a guide to the technical acquisition of images and recognition of artifacts that arise during HPDI.