5,660 research outputs found

    Identifying consistent biomechanical parameters across rising-to-walk subtasks to inform rehabilitation in practice: A systematic literature review

    Get PDF
    © 2020 Elsevier B.V. Background: :The best approach to rehabilitate the control of everyday whole-body movement (e.g. rise-to-walk) after pathology remains unclear in part because the associated controlled performance variables are not known. Rise-to-walk can be performed fluidly (sit-to-walk) or non-fluidly (sit-to-stand, proceeded by gait-initiation). Biomechanical variables that remain consistent in health regardless of how rise-to walk is performed represent controlled performance variable candidates which could monitor rehabilitative change. Research Question: :To determine if any biomechanical parameters remain consistent across rising-to-walk (RTW) subtasks (sit-to-stand, gait-initiation, and sit-to-walk) in healthy adults for purposes of movement control assessment in clinical practice. Methods: :Data sources included Medline, Cinahl, and Scopus databases, and the grey literature. Study selection was based on eligibility criteria and must have reported spatiotemporal, kinematic and/or kinetic biomechanical parameters featuring >1 RTW subtask. Data extraction and synthesis; standardised-mean-differences (SMDs) were calculated (pooled if replicated in >1 study) for each parameter. Consistency was determined if SMD95 %CIs included the zero-effect line. Results: :Nine studies (n = 99) were included (40 ± 7.5yrs). Seven parameters were replicated in >1 study and subjected to meta-analysis (fixed-effect model). Two were consistent between sit-to-stand and sit-to-walk: flexion-momentum time (M(95 %CI) = 0.055(-0.423 to 0.533); p = 0.823) and peak whole-body-centre-of-mass vertical velocity (M(95 %CI)= -0.415(-0.898 to 0.069); p = 0.093); and centre-of-pressure to whole-body-centre-of-mass distance at toe-off (M(95 %CI)= -0.137(-0.712 to 0.439); p = 0.642) between gait-initiation and sit-to-walk. Another 20 parameters were consistent based on single-study SMDs. Significance: :Consistent parameters might exist across RTW subtasks. However, the evidence is based on few studies with small samples and variable RTW protocols. Future studies designed to confirm consistency using a standardised RTW protocol are needed

    Discrepancies in autologous bone marrow stem cell trials and enhancement of ejection fraction (DAMASCENE): weighted regression and meta-analysis

    Get PDF
    Objective To investigate whether discrepancies in trials of use of bone marrow stem cells in patients with heart disease account for the variation in reported effect size in improvement of left ventricular function. Design Identification and counting of factual discrepancies in trial reports, and sample size weighted regression against therapeutic effect size. Meta-analysis of trials that provided sufficient information. Data sources PubMed and Embase from inception to April 2013. Eligibility for selecting studies Randomised controlled trials evaluating the effect of autologous bone marrow stem cells for heart disease on mean left ventricular ejection fraction. Results There were over 600 discrepancies in 133 reports from 49 trials. There was a significant association between the number of discrepancies and the reported increment in EF with bone marrow stem cell therapy (Spearman’s r=0.4, P=0.005). Trials with no discrepancies were a small minority (five trials) and showed a mean EF effect size of −0.4%. The 24 trials with 1-10 discrepancies showed a mean effect size of 2.1%. The 12 with 11-20 discrepancies showed a mean effect of size 3.0%. The three with 21-30 discrepancies showed a mean effect size of 5.7%. The high discrepancy group, comprising five trials with over 30 discrepancies each, showed a mean effect size of 7.7%. Conclusions Avoiding discrepancies is difficult but is important because discrepancy count is related to effect size. The mechanism is unknown but should be explored in the design of future trials because in the five trials without discrepancies the effect of bone marrow stem cell therapy on ejection fraction is zero

    DNMTs are required for delayed genome instability caused by radiation

    Get PDF
    This is an open-access article licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. The article may be redistributed, reproduced, and reused for non-commercial purposes, provided the original source is properly cited - Copyright @ 2012 Landes Bioscience.The ability of ionizing radiation to initiate genomic instability has been harnessed in the clinic where the localized delivery of controlled doses of radiation is used to induce cell death in tumor cells. Though very effective as a therapy, tumor relapse can occur in vivo and its appearance has been attributed to the radio-resistance of cells with stem cell-like features. The molecular mechanisms underlying these phenomena are unclear but there is evidence suggesting an inverse correlation between radiation-induced genomic instability and global hypomethylation. To further investigate the relationship between DNA hypomethylation, radiosensitivity and genomic stability in stem-like cells we have studied mouse embryonic stem cells containing differing levels of DNA methylation due to the presence or absence of DNA methyltransferases. Unexpectedly, we found that global levels of methylation do not determine radiosensitivity. In particular, radiation-induced delayed genomic instability was observed at the Hprt gene locus only in wild-type cells. Furthermore, absence of Dnmt1 resulted in a 10-fold increase in de novo Hprt mutation rate, which was unaltered by radiation. Our data indicate that functional DNMTs are required for radiation-induced genomic instability, and that individual DNMTs play distinct roles in genome stability. We propose that DNMTS may contribute to the acquirement of radio-resistance in stem-like cells.This study is funded by NOTE, BBSRC and the Royal Society Dorothy Hodgkin Research Fellowship

    Outcomes Following eHealth Weight Management Interventions in Adults With Overweight and Obesity From Low Socioeconomic Groups: Protocol for a Systematic Review.

    Get PDF
    BACKGROUND: Obesity is a complex health condition with multiple associated comorbidities and increased economic costs. People from low socioeconomic status (SES) backgrounds are more likely to be overweight and obese and are less successful in traditional weight management programs. It is possible that eHealth interventions may be more successful in reaching people from low SES groups than traditional face-to-face models, by overcoming certain barriers associated with traditional interventions. It is not yet known, however, if eHealth weight management interventions are effective in people living with overweight and obesity from a low SES background. OBJECTIVE: The primary aim of this study is to evaluate the efficacy of eHealth weight management interventions for people with overweight and obesity from low SES groups. METHODS: A systematic review on relevant electronic databases (MEDLINE, Embase, Emcare, and CINAHL) will be undertaken to identify eligible studies published in English up until May 2021. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement to guide the systematic review, two reviewers will independently screen, select, and extract data and complete a risk of bias assessment of search results according to predefined criteria. Studies that have investigated an eHealth weight management intervention within a low SES population will be included. Primary outcomes include weight, BMI, and percentage weight change compared at baseline and at least one other time point. Secondary outcomes may include a range of anthropometric and physical fitness and activity measures. If sufficient studies are homogeneous, then we will pool results of individual outcomes using meta-analysis. RESULTS: Searches have been completed, resulting in 2256 studies identified. Once duplicates were removed, 1545 studies remained for title and abstract review. CONCLUSIONS: The use of eHealth in weight management programs has increased significantly in recent years and will continue to do so; however, it is uncertain if eHealth weight management programs are effective in a low SES population. The results of this systematic review will therefore provide a summary of the evidence for interventions using eHealth for people living with overweight and obesity and from a low SES background. TRIAL REGISTRATION: PROSPERO International Prospective Register of Systematic Reviews CRD42021243973; https://tinyurl.com/2p8fxtnw. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/34546

    Role of the mesoamygdaloid dopamine projection in emotional learning

    Get PDF
    Amygdala dopamine is crucially involved in the acquisition of Pavlovian associations, as measured via conditioned approach to the location of the unconditioned stimulus (US). However, learning begins before skeletomotor output, so this study assessed whether amygdala dopamine is also involved in earlier 'emotional' learning. A variant of the conditioned reinforcement (CR) procedure was validated where training was restricted to curtail the development of selective conditioned approach to the US location, and effects of amygdala dopamine manipulations before training or later CR testing assessed. Experiment 1a presented a light paired (CS+ group) or unpaired (CS- group) with a US. There were 1, 2 or 10 sessions, 4 trials per session. Then, the US was removed, and two novel levers presented. One lever (CR+) presented the light, and lever pressing was recorded. Experiment 1b also included a tone stimulus. Experiment 2 applied intra-amygdala R(+) 7-OH-DPAT (10 nmol/1.0 A mu l/side) before two training sessions (Experiment 2a) or a CR session (Experiment 2b). For Experiments 1a and 1b, the CS+ group preferred the CR+ lever across all sessions. Conditioned alcove approach during 1 or 2 training sessions or associated CR tests was low and nonspecific. In Experiment 2a, R(+) 7-OH-DPAT before training greatly diminished lever pressing during a subsequent CR test, preferentially on the CR+ lever. For Experiment 2b, R(+) 7-OH-DPAT infusions before the CR test also reduced lever pressing. Manipulations of amygdala dopamine impact the earliest stage of learning in which emotional reactions may be most prevalent

    Mud-dominated basin margin progradation: processes and implications

    Get PDF
    The accretion of coarse-grained material at the shelf-edge rollover has been emphasized in studies of basin margin progradation, despite fine grained sediment (clay and silt) representing a volumetrically more significant component of subaqueous clinothems. The timing and processes of fine-grained sediment transport across the shelf and onto the slope remains an understudied facet of sedimentary basin stratigraphy. Three exhumed basin margin-scale clinothems of the Permian Waterford Formation, in the Karoo Basin, South Africa, offer outcrop examples of margin development through the accretion of mud during flooded shelf conditions. The progradation of wave/storm-influenced sandy shelf topset deposits over a thick mudstone succession and beyond a previously established sand-rich shelf-edge rollover suggests that some periods of basin margin progradation took place exclusively via dilute mud-rich gravity flows. Detailed outcrop and core study of offshore mudstones reveals a high content of organic debris and mica. Individual beds show normal and inverse grading, internal erosion surfaces and moderate to low bioturbation, reflecting relatively stressed conditions in frequently supplied outer shelf to upper slope regions. The estimated low gradient (<0.7º) of the Karoo Basin margin and prevailing wave/storm conditions facilitated prolonged suspension of fluid mud and transport across the shelf and beyond the shelf-edge rollover in sediment gravity flows. This study represents a rare example of mudstone-dominated shelf-edge rollover deposits documented at outcrop and core, and demonstrates how fine-grained sediment accretion can play a significant role in basin margin progradation. Conventional depositional models do not adequately account for progradation of basin margins in the absence of sand supply, which implies potential risks in the identification of shelf edge rollover positions and application of trajectory analysis in strongly progradational margins

    Sit-to-walk and sit-to-stand-and-walk task dynamics are maintained during rising at an elevated seat-height independent of lead-limb in healthy individuals

    Get PDF
    © 2016 Elsevier B.V.Introduction: Sit-to-walk (STW) is a common transitional motor task not usually included in rehabilitation. Typically, sit-to-stand (STS), pause, then gait initiation (GI) before walking is used, which we term sit-to-stand-and-walk (STSW). Separation between centre-of-pressure (COP) and whole-body centre-of-mass (BCOM) during GI is associated with dynamic postural stability. Rising from seats higher than knee-height (KH) is more achievable for patients, but whether this and/or lead-limb significantly affects task dynamics is unclear. This study tested whether rising from seat-heights and lead-limb affects STW and STSW task dynamics in young healthy individuals. Methods: Ten (5F) young (29 ± 7.7 years) participants performed STW and STSW from a standardised position. Five trials of each task were completed at 100 and 120%KH leading with dominant and non-dominant legs. Four force-plates and optical motion capture delineated key movement events and phases with effect of seat-height and lead-limb determined by 2-way ANOVA within tasks. Results: At 120%KH, lower peak vertical ground-reaction-forces (vGRFs) and vertical BCOM velocities were observed during rising irrespective of lead-limb. No other parameters differed between seat-heights or lead-limbs. During GI in STSW there was more lateral, and less posterior, COP excursion than expected. Conclusion: Reduction in vGRFs and velocity during rising at 120%KH is consistent with reduced effort in young healthy individuals and is likely therefore to be an appropriate seat-height for patients. Lead-limb had no effect upon STSW or STW parameters suggesting that normative data independent of lead-limb can be utilised to monitor motor rehabilitation should differences be observed in patients. STSW should be considered an independent movement transition

    Proof Relevant Corecursive Resolution

    Full text link
    Resolution lies at the foundation of both logic programming and type class context reduction in functional languages. Terminating derivations by resolution have well-defined inductive meaning, whereas some non-terminating derivations can be understood coinductively. Cycle detection is a popular method to capture a small subset of such derivations. We show that in fact cycle detection is a restricted form of coinductive proof, in which the atomic formula forming the cycle plays the role of coinductive hypothesis. This paper introduces a heuristic method for obtaining richer coinductive hypotheses in the form of Horn formulas. Our approach subsumes cycle detection and gives coinductive meaning to a larger class of derivations. For this purpose we extend resolution with Horn formula resolvents and corecursive evidence generation. We illustrate our method on non-terminating type class resolution problems.Comment: 23 pages, with appendices in FLOPS 201

    Parameters that remain consistent independent of pausing before gait-initiation during normal rise-to-walk behaviour delineated by sit-to-walk and sit-to-stand-and-walk.

    Get PDF
    BACKGROUND: Rising-to-walk is an everyday transitional movement task rarely employed in gait rehabilitation. Sit-to-walk (STW) and sit-to-stand-and-walk (STSW), where a pause separates sit-to-stand and gait-initiation (GI) represent extremes of rising-to-walk behaviour. Delayed GI can indicate pathological impairment but is also observed in healthy individuals. We hypothesise that healthy subjects express consistent biomechanical parameters, among others that differ, during successful rising-to-walk task performance regardless of behaviour. This study therefore sought to identify if any parameters are consistent between STW and STSW in health because they represent normal rise-to-walk performance independent of pause, and also because they represent candidate parameters sensitive enough to monitor change in pathology. METHODS: Ten healthy volunteers performed 5 trials of STW and STSW. Event timing, ground-reaction-forces (GRFs), whole-body-centre-of-mass (BCoM) displacement, and centre-of-pressure (CoP) to extrapolated BCoM (xCoM) distance (indicator of positional stability) up to the 3rd step were compared between-tasks with paired t-tests. For consistent parameters; agreement between-tasks was assessed using Bland-Altman analyses and minimal-detectable-change (MDC) calculations. RESULTS: Mean vertical GRFs, peak forward momentum and fluidity during rising; CoP-xCoM separation at seat-off, upright, GI-onset, and steps1-2; and forward BCoM velocity were all significantly greater in STW. In contrast, peak BCoM vertical momentum, flexion-momentum time, and 3rd step stability were consistent between tasks and yielded acceptable reliability. CONCLUSION: STW is a more challenging task due to the merging of rising with GI reflected by greater CoP-xCoM separation compared to STSW indicative of more positional instability. However, BCoM vertical momentum, flexion-momentum time, and step3 stability remained consistent in healthy individuals and are therefore candidates with which to monitor change in gait rehabilitation following pathology. Future studies should impose typical pause-durations observed in pathology upon healthy subjects to determine if the parameters we have identified remain consistent
    • …
    corecore