Age-matched Adults Research Articles

Changes of balance control in individuals with lumbar degenerative spine disease after lumbar surgery: a longitudinal study

Background ContextLumbar degenerative spine disease (DSD) with neurological symptoms is the most common indication requiring lumbar surgery when nonoperative treatment is not effective. Individuals with lumbar DSD have sensory, proprioception, and musculoskeletal system alterations, which may result in balance impairment. However, evidence regarding balance recovery in individuals with lumbar DSD after lumbar surgery is limited. PurposeTo evaluate balance control, pain, and functional activities in individuals with lumbar DSD after lumbar surgery. Study Design/SettingA prospective study with a cross-sectional control group. Patient SampleSeventy individuals with lumbar DSD (DSD group) and 30 age-matched healthy adults (control group) were recruited. Participants in the DSD group were diagnosed by a neurological surgeon and received lumbar surgery according to relevant imaging findings and neurological symptoms. Outcome MeasuresClinical assessments, including a visual analogue scale (VAS), the Oswestry Disability Index (ODI), and the Roland-Morris Disability Questionnaire (RMDQ), were performed in the DSD group only. Balance control was assessed in all participants using the root mean square (RMS) distance of the center of pressure (COP) in anteroposterior and mediolateral directions. MethodsAll participants were instructed to stand in natural stance and Romberg stance with eyes open and eyes closed on a force platform for 35 seconds, respectively. The assessments were performed in the DSD group at four time points: preoperative phase (baseline), 3 months, 6 months, and 12 months postoperatively. In the age-matched healthy control group, only one assessment on the recruitment day was performed. ResultsThe VAS, ODI, and RMDQ scores of the DSD group significantly improved after lumbar surgery (p<.001). The RMS distance of COP in the DSD group significantly decreased after lumbar surgery (p<.017) compared with baseline in most of the testing conditions. However, the RMS distance of the COP in the DSD group after surgery was significantly greater than in the healthy control group (p<.05), especially 6 months and 12 months postoperatively. ConclusionsBalance control, pain, and functional activities of individuals with lumbar DSD showed improvement after lumbar surgery. However, balance control in individuals with lumbar DSD was still less stable than in age-matched healthy adults from 6 to 12 months after surgery. Therefore, individuals with lumbar DSD require fall prevention programs after lumbar surgery, including balance assessments and postoperative balance training.

Current health status and history of traumatic brain injury among Ohio adults

IntroductionLifetime history of traumatic brain injury (TBI) with loss of consciousness (LOC) is prevalent in 21% of adult, non-institutionalised residents of Ohio. Prior history has been associated with lower incomes,...

Cognitive-motor interference in post-stroke individuals and healthy adults under different cognitive load and task prioritization conditions.

[Purpose] We aimed to compare the effects of cognitive load and task prioritization on dual task strategies in patients with stroke and healthy adults in order to clarify the characteristics of cognitive-motor interference. [Participants and Methods] In total, 26 patients with stroke and 26 age-matched healthy adults (controls) performed the Timed Up and Go Test while performing a serial subtraction task from random numbers between 90 and 100. Dual task was measured under four conditions in which two difficulty levels of “3 subtraction” and “7 subtraction” were multiplied by two prioritizing tasks that involved “paying equal attention to both walking and subtraction tasks” (no priority) and “paying attention while mainly focusing on subtraction tasks” (cognitive priority). [Results] Increasing cognitive load and prioritizing cognitive tasks affected motor performance in terms of the amount of time and number of steps required to complete the Timed Up and Go Test in both the patients and controls. However, cognitive load and task prioritization did not affect cognitive performance. [Conclusion] When cognitive load increases and instructions are given to prioritize increases in cognitive load, patients with stroke use the “posture first” strategy to stabilize their gait as effectively as healthy adults do.

Oxidative Stress Parameters, Selenium Levels, DNA Damage, and Phthalate Levels in Plastic Workers.

Di(2-ethylhexyl)phthalate (DEHP) is the most widely used phthalate. DEHP is highly used in PVC floorings and PVC windows and carpeting. The objective of this study was to determine sex hormone levels, oxidative stress parameters, selenium levels, DNA damage, and phthalate levels in plastics workers (n = 24, age = 20-58 years) working in the production of rubber mechanical goods and exposed to DEHP in workplace. The control group (n = 29, age = 25-54, all male) was selected from age-matched healthy adults. Antioxidant parameters and DNA damage were determined by spectrophotometry. Selenium levels were determined by atomic absorption spectroscopy. Plasma hormone levels were measured by chemiluminescence microparticle immunoassay. Plasma phthalate levels were determined by high-pressure liquid chromatography. Plastic workers had lower serum testosterone and free T4 levels and higher follicle-stimulating hormone levels vs. controls. Liver enzyme activities were markedly higher in workers vs. controls. There were also increases in plasma glutathione peroxidase levels and marked decreases in plasma selenium and erythrocyte total glutathione levels in plastics workers (P < 0.05 vs. control). Plasma 8-hydroxy-2'-deoxyguanosine levels were 14-fold higher in plastics workers than in controls. Plasma DEHP and mono(2-ethylhexyl)phthalate were also markedly higher in workers vs. controls. The results of this study show that occupational exposure to DEHP may lead to disturbances in sex hormones, increased liver problems, higher oxidative stress and DNA damage levels, and lower trace element concentrations in workers. More comprehensive and mechanistic studies with higher numbers of subjects are needed to show the unwanted effects of occupational exposure to DEHP.

Hearing loss and verbal memory assessment among older adults.

Research has found that adults with hearing loss perform worse on cognitive testing than adults without hearing loss; however, heavy emphasis on tests involving auditory stimuli may overdiagnose cognitive impairment among individuals with hearing loss. This study compared visual- and auditory-verbal memory tests among adults with and without hearing loss. Forty-one adults with hearing loss (HL) and 41 age-matched adults with normal hearing (NH) completed a neuropsychological battery that included auditory and visual versions of the Hopkins Verbal Learning Testing-Revised (HVLT-R). A natural auditory condition presented HVLT-R stimuli at normal speaking volume. A crossed auditory condition presented HVLT-R stimuli to individuals with hearing loss with amplified acoustic intensity and to individuals with normal hearing under hearing loss simulation. Mixed-model ANOVA indicated significant group (HL vs. NH) by condition (visual, natural auditory, crossed auditory) interactions for HVLT-R performance, with large effect sizes. The HL group performed significantly worse than the NH group on the natural auditory version; however, the NH group performed significantly worse than the HL group on the crossed condition. The groups were equivalent on the visual condition and all other cognitive tests, showing small effect sizes. Moreover, for the HL group, visual HVLT-R correlated with other cognitive tests whereas auditory versions did not. Cognitively intact older adults with hearing loss appeared impaired on auditory-verbal memory assessment under typical administration conditions. Visual assessment of verbal memory showed evidence of superior validity and is a viable alternative method to assess memory function especially in older populations. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Reliability of the Maximal Step Length Test and Its Correlation with Motor Function in Chronic Stroke Survivors.

Objective This study aimed to (1) investigate the interrater, intrarater, and test-retest reliabilities, as well as the minimal detectable change, of the Maximal Step Length test (MSL) in stroke survivors, (2) examine the concurrent validity of MSL with other stroke-specific impairment measurements in stroke survivors, and (3) compare the MSL performances of stroke survivors and those of age-matched healthy older adults in different directions. Design Cross-sessional study. Setting University-based research laboratory. Participants Stroke survivors (n = 48) and age-matched healthy older adults (n = 39). Methods Stroke survivors were assessed with MSL, lower limb muscle strength, Limits of Stability (LOS) Test, Berg Balance Scale (BBS), 5-meter walk test, and Activities-specific Balance Confidence (ABC) scale by two trained assessors in 1 session. Their performance on MSL was reassessed 1 week later to establish the test-retest reliability. Healthy older adults were assessed with MSL only. Intraclass correlation coefficient (ICC) was used to assess the reliability of MSL and Spearman's rho was used to quantify the strength of correlations between MSL and secondary outcomes. Between-group differences of MSL were assessed with the independent t-test. Results The MSL exhibited excellent intrarater, interrater, and test-retest reliabilities [ICC: 0.885–1.000]. Significant correlations (ρ: 0.447–0.723) were demonstrated between MSLs in most directions and muscle strengths of the affected legs, BBS scores, and walking speeds. The step lengths differed significantly between stroke survivors and healthy older adults in the forward, backward, and sideways directions on both the affected and less affected sides. Conclusions The MSL is a reliable, valid, and easily administered test of the stepping capabilities of stroke survivors. Stroke survivors had significant shorter MSLs in all directions than the age-matched healthy older adults.

Effects of Phase-Locking Deficits on Speech Recognition in Older Adults With Presbycusis.

Objective: People with presbycusis (PC) often report difficulties in speech recognition, especially under noisy listening conditions. Investigating the PC-related changes in central representations of envelope signals and temporal fine structure (TFS) signals of speech sounds is critical for understanding the mechanism underlying the PC-related deficit in speech recognition. Frequency-following responses (FFRs) to speech stimulation can be used to examine the subcortical encoding of both envelope and TFS speech signals. This study compared FFRs to speech signals between listeners with PC and those with clinically normal hearing (NH) under either quiet or noise-masking conditions.Methods: FFRs to a 170-ms speech syllable /da/ were recorded under either a quiet or noise-masking (with a signal-to-noise ratio (SNR) of 8 dB) condition in 14 older adults with PC and 13 age-matched adults with NH. The envelope (FFRENV) and TFS (FFRTFS) components of FFRs were analyzed separately by adding and subtracting the alternative polarity responses, respectively. Speech recognition in noise was evaluated in each participant.Results: In the quiet condition, compared with the NH group, the PC group exhibited smaller F0 and H3 amplitudes and decreased stimulus-response (S-R) correlation for FFRENV but not for FFRTFS. Both the H2 and H3 amplitudes and the S-R correlation of FFRENV significantly decreased in the noise condition compared with the quiet condition in the NH group but not in the PC group. Moreover, the degree of hearing loss was correlated with noise-induced changes in FFRTFS morphology. Furthermore, the speech-in-noise (SIN) threshold was negatively correlated with the noise-induced change in H2 (for FFRENV) and the S-R correlation for FFRENV in the quiet condition.Conclusion: Audibility affects the subcortical encoding of both envelope and TFS in PC patients. The impaired ability to adjust the balance between the envelope and TFS in the noise condition may be part of the mechanism underlying PC-related deficits in speech recognition in noise. FFRs can predict SIN perception performance.

Comparing Balance Performance on Force Platform Measures in Individuals with Parkinson's Disease and Healthy Adults.

Introduction Postural instability is a known contributing factor to balance dysfunction and increased fall risk in those with Parkinson's disease (PD). Computerized posturography employing a force platform system provides objective, quantitative assessments of postural control impairments. This study examines balance performance as measured by force platform (FP) tests in persons with PD compared to age-matched healthy adults. Secondarily, we examine if these FP measures provide diagnostic and clinically meaningful information about the underlying balance impairments in the PD population. Methods Participants—42 individuals with PD (Hoehn and Yahr stage = 2.33 ± 0.77) and 55 age-matched healthy adults—were assessed on three standardized balance measures on a computerized force platform system. Between groups, comparisons of FP performance were analyzed using independent t-test. Within the group, comparisons for the PD cohort were analyzed using ANOVA for comparing disease stage and Mann–Whitney U test for PD subtypes. Results The PD cohort demonstrated significantly greater postural instability on the sensory organization test (SOT) measures (P=0.013, CI-95% = 1.286 to 10.37) and slower movement velocity on the limits of stability (LOS) test (P=0.001, CI-95% = 0.597 to 1.595) than the healthy cohort, suggesting that these tests were sensitive to detect sensory integration and voluntary postural control deficits in the PD cohort. Within the PD group, the SOT differentiated between H&Y stages 1–3. The motor control test (MCT) detected changes in reactive postural control mainly in later disease stages. All three FP tests distinguished between PD subtypes, with the Posture Gait Instability subtype demonstrating poorer balance performance than Tremor Dominant subtype. Conclusion These findings suggest FP measures provide clinically meaningful, diagnostic information in the examination of balance impairments in individuals with PD. FP measures may inform clinicians regarding intrinsic balance deficits and guide them in designing targeted balance interventions to reduce fall risk in persons with PD.

Attention-Related Brain Activation Is Altered in Older Adults With White Matter Hyperintensities Using Multi-Echo fMRI.

Cognitive decline is often undetectable in the early stages of accelerated vascular aging. Attentional processes are particularly affected in older adults with white matter hyperintensities (WMH), although specific neurovascular mechanisms have not been elucidated. We aimed to identify differences in attention-related neurofunctional activation and behavior between adults with and without WMH. Older adults with moderate to severe WMH (n = 18, mean age = 70 years), age-matched adults (n = 28, mean age = 72), and healthy younger adults (n = 19, mean age = 25) performed a modified flanker task during multi-echo blood oxygenation level dependent functional magnetic resonance imaging. Task-related activation was assessed using a weighted-echo approach. Healthy older adults had more widespread response and higher amplitude of activation compared to WMH adults in fronto-temporal and parietal cortices. Activation associated with processing speed was absent in the WMH group, suggesting attention-related activation deficits that may be a consequence of cerebral small vessel disease. WMH adults had greater executive contrast activation in the precuneous and posterior cingulate gyrus compared to HYA, despite no performance benefits, reinforcing the network dysfunction theory in WMH.

An altered spatiotemporal gait adjustment during a virtual obstacle crossing task in patients with diabetic peripheral neuropathy

This study investigates spatiotemporal gait adjustments that occur while stepping over virtual obstacles during treadmill walking in people with/without diabetic peripheral neuropathy (DPN). Eleven adults with Type 2 diabetes mellitus, ten DPN, and 11 age-matched healthy adults (HTY) participated in this study. They stepped over forthcoming virtual obstacles during treadmill walking. Outcomes such as success rate, spatiotemporal gait characteristics during obstacle crossing, and correlations between these variables were evaluated. The results partially supported our hypotheses that when comparing with HTY and DM, people with DPN adopted a crossing strategy which decreased obstacle crossing success rate and maximal toe elevation, and increased stride time and stance time during virtual obstacle crossing. This might be due to the compromised somatosensory functions of their lower extremity which may increase the risk of falling. This study also found an inter-leg relationship which may be applied to future stepping or obstacle crossing training that incorporates both legs as a means for improving outcomes of the trailing leg during daily obstacle negotiation.

Acute and chronic effects of soccer game on the retinal vessel diameters in middle-aged adults.

Although changes in retinal vessel diameter is a new biomarker for the evaluation of cardiovascular risk factors, limited information is available regarding the effects of endurance exercises on retinal microcirculation. Thus, we aimed to evaluate both chronic and acute effects of soccer game on the diameters of retinal vessels in middle-aged players. Retinal vessel diameters were measured in 12 middle-aged amateur players (44.4±7.0 years of age) with more than four years of soccer playing experience and 12 age-matched sedentary adults (49.7±7.1 years of age). In soccer players, diameters were also measured immediately after the soccer game. Cardiovascular risk profiles (anthropometry and body composition and blood pressure [BP]) and physical activity levels were also measured. Soccer players had wider retinal vessels than controls (P<0.05), resulting in greater arteriolar-to-venular diameter ratio (AVR) (P<0.05). Greater sports-related physical activity, lower body mass index (BMI) and fat mass were observed for soccer players compared to the controls (P<0.05), whereas BP did not differ. Physical activity level correlated positively with temporal retinal arteriolar (TRA) diameter and with AVR (P<0.05), whereas TRA diameter correlated negatively with BMI and fat mass (P<0.05). A significant correlation between temporal retinal venule (TRV) diameter and TRA diameter (P<0.05) was observed. The acute soccer game increased BP (P<0.05) and induced TRV dilatation (P<0.05). In middle-aged amateur soccer players, improvement of the retinal microcirculation was observed. Cardiovascular risk factors and physical inactivity were associated with adverse retinal microvascular alterations. In terms of acute effects, soccer play causes venular, but not arteriolar dilatation for middle-aged adults.

Determinants of the 6-minute pegboard and ring test as an unsupported upper-extremity exercise capacity measure in older adults with chronic obstructive pulmonary disease

Upper extremities play an important role in performing of many activities of daily living. Physical and pathological changes limit upper extremity functions in older adults with chronic obstructive pulmonary disease (COPD). Although the 6-minute pegboard and ring test (6PBRT) is a reliable and commonly used method for the assessment of unsupported upper-extremity exercise capacity in patients with COPD, there is lack of evidence about the possible determinants of the 6PBRT score. The study aimed to investigate the possible determinants of the 6PBRT in older adults with COPD. Fifty-two older adults (age ≥ 65years) with stable COPD and 23 age-matched healthy older adults participated in this study. Demographic characteristics, unsupported upper-extremity exercise capacity, pulmonary function, functional exercise capacity, disease related symptoms, peripheral and respiratory muscle strength were evaluated. Stepwise multiple linear regression analysis was used to investigate the possible determinants of the 6PBRT score. The 6PBRT score was significantly higher in healthy participants compared with those with COPD (p = 0.024). In participants with COPD, shoulder flexor muscle strength, age and functional exercise capacity were significant and independent predictors of the unsupported upper-extremity exercise capacity with explaining 55.4% of the variance. This study suggests that shoulder flexor muscle strength, age and functional exercise capacity are independent determinants of the unsupported upper-extremity exercise capacity assessed by the 6PBRT in older adults with COPD.

Immunopathological Features of Severe Chronic Atopic Keratoconjunctivitis and Effects of Topical Cyclosporine Treatment

ABSTRACTPurpose: To assess differential roles of inflammatory cells in pathophysiology of severe atopic keratoconjunctivitis (AKC) and evaluate immunomodulatory effects of topical cyclosporine A (CsA).Methods: A total of 10 patients with severe, steroid-dependent/resistant chronic active AKC were treated using frequent topical CsA 0.05% as monotherapy for 2 months. Conjunctival biopsy specimens before and after treatment were examined using immunohistochemistry. A total of 10 healthy age-matched adults served as the control group.Results: Baseline AKC samples revealed greater cluster of differentiation 4 (CD4), interferon gamma (IFNγ), human leukocyte antigen–D-related (HLA-DR) positive cell densities compared with healthy controls (P < 0.05), as well as interleukin (IL)-17 (P = 0.08). Topical CsA treatment induced a significant reduction in CD4 and IL-17 expressions (P < 0.05); post-treatment levels were same as normals (P > 0.05). Despite reduction after treatment (P = 0.06), HLA-DR expression remained higher than controls (P < 0.05).Conclusions: AKC-related conjunctival inflammation appears to be mediated by delayed hypersensitivity. In this short-term trial, frequent topical CsA improved conjunctival inflammation.

The Work Disability Functional Assessment Battery (WD-FAB): Development and validation review

Comprehensive, efficient assessment of work-related activity limitations is imperative to government disability programs and clinicians working with patients experiencing work limitations. This article describes the development and initial validation of a newly developed instrument: the Work Disability Functional Assessment Battery (WD-FAB). The WD-FAB characterises physical and mental function across 8 key dimensions related to work: Basic Mobility; Upper Body Function; Fine Motor Function; Community Mobility; Mood & Emotions; Resilience & Sociability; Self-Regulation; and Cognition & Communication. The WD-FAB draws upon a pool of over 300 items to generate scores for all 8 scales in under 15 minutes. WD-FAB scores allow direct comparisons between individuals with self-reported activity limitations and sex- and age-matched adults. Future research with the WD-FAB in both the US and Europe has potential implications for enhancing disability assessment methodologies within the context of disability determination and insurance medicine systems.

Brain-derived neurotrophic factor, insulin like growth factor-1 and inflammatory cytokine responses to continuous and intermittent exercise in patients with type 1 diabetes

AimsType 1 diabetes mellitus (T1DM) is an important risk factor for cognitive decline and motor dysfunction due to progressive muscular atrophy. Chronic hyperglycemia may be responsible for impaired vascular function, loss of muscle mass, and morphological abnormalities in the myocytes. For the proper functioning of the neuromuscular system, two crucial growth factors are necessary: brain-derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1), whose reduced expressions have been implicated in progressive neuropathy and muscle atrophy in patients with T1DM.The aim of the study was to compare the effects of two different exercise regimes (continuous and intermittent) on BDNF, IGF-1, blood glucose and inflammatory cytokine responses in young adults with and without Type 1 diabetes. MethodsFourteen patients (aged: 26.9 years) with T1DM and age-matched adults without diabetes participated in a 40 min continuous exercise (ExC, 50% of lactate threshold) and a high intensity intermittent exercise (ExInt, 120% of lactate threshold). During the study the patients performed self-monitoring of blood glucose levels (SMBG) under glycemic control. The effects of ExC and ExInt on BDNF, IGF-1, insulin like growth factor binding protein (IGFBP-3), insulin (INS), vascular endothelial growth factor (VEGF), transforming growth factor beta (TGF-β) and tumor necrosis factor alpha (TNF-α) were analyzed. ResultsBDNF and IGF-1 baseline serum levels were significantly lower in the T1DM patients compared to the healthy controls, but we found that ExInt and ExC significantly increase the secretion of BDNF and IGF-1 levels. Significant increases in BDNF and TGF-β levels, higher blood glucose decline, and a lower incidence of hypoglycaemia in ExInt compared to ExC were observed. Lower IGFBP-3 concentrations were revealed in T1DM patients in response to ExInt compared to ExC, suggesting a positive effect on IGF-1/IGFBP-3 ratio and the bioavailability of IGF-1. ConclusionsAccording to our results physical exercise has beneficial effects on serum BDNF and IGF-1 levels. A high-intensity intermittent exercise may be more effective at reducing the risk of exercise-induced glycaemic disorders in the T1DM patients as compared to continuous exercise.

The neural correlates of perceived energy levels in older adults with late-life depression

Late-life depression is common among older adults. Although white-matter abnormality is highly implicated, the extent to which the corticospinal tract is associated with the pathophysiology of late-life depression is unclear. The current study aims to investigate the white-matter structural integrity of the corticospinal tract and determine its cognitive and functional correlates in older adults with late-life depression. Twenty-eight older adults with clinical depression and 23 healthy age-matched older adults participated in the study. The white matter volume and the white matter hyperintensities (WMHs) of the corticospinal tract, as well as the global WMHs, were measured. Psychomotor processing speed, severity of depression, perceived levels of energy and physical functioning were measured to examine the relationships among the correlates in the depressed participants. The right corticospinal tract volume was significantly higher in depressed older adults relative to healthy controls. Moreover, the right corticospinal tract volume was significantly associated with the overall severity of depression and accounted for 17% of its variance. It further attenuated the relationship between the severity of depression and perceived levels of energy. Our findings suggested that higher volume in the right corticospinal tract is implicated in LLD and may relate to lower perceived levels of energy experienced by older adults with depression.

Altered frequency of Th17 and Treg cells in new‐onset systemic lupus erythematosus patients

T helper 17 (Th17) and regulatory T (Treg) cells play an important role in pathogenesis of systemic lupus erythematosus (SLE). Their imbalance was reported in treated SLE patients, while very little is known about the relationship between Th17 and Treg cells in new-onset untreated SLE patients. To assess the role of Th17/Treg cells in the pathogenesis of new-onset SLE. Thirty-nine new-onset SLE patients and 33 age-matched healthy adults were enrolled. We analysed Th17 and Treg cells in different level, including their frequencies in peripheral blood mononuclear cell, the expression of interleukin-17 A (IL-17A) and forkhead box P3 (FoxP3) proteins, the expression of retinoid-related orphan nuclear receptor γt (RORγt) and FoxP3 genes and plasma level of IL-17A. The frequency of Th17 and Treg cells, the expression of IL-17A among Th17 cell, the plasma level of IL-17A, the expression of RORγt and FoxP3 genes were all significantly higher in SLE patients. Th17 cells were negatively correlated with Treg cells. We also found that plasma level of IL-17A was positively correlated with SLE disease activities index (SLEDAI) scores and an equation among the level of C3, IgA, IL-17A and SLEDAI scores. Results indicate that Th17 and Treg cells take roles in the pathogenesis of SLE. Th17 cells might suppress the differentiation of Treg cells, and feedback effects might exist between them during SLE pathogenesis. The measure of plasma level of IL-17A may be useful for evaluation of disease activity in new-onset SLE patients.

Eye movement control during visual pursuit in Parkinson's disease.

BackgroundPrior studies of oculomotor function in Parkinson’s disease (PD) have either focused on saccades without considering smooth pursuit, or tested smooth pursuit while excluding saccades. The present study investigated the control of saccadic eye movements during pursuit tasksand assessed the quality of binocular coordinationas potential sensitive markers of PD.MethodsObservers fixated on a central cross while a target moved toward it. Once the target reached the fixation cross, observers began to pursue the moving target. To further investigate binocular coordination, the moving target was presented on both eyes (binocular condition), or on one eye only (dichoptic condition).ResultsThe PD group made more saccades than age-matched normal control adults (NC) both during fixation and pursuit. The difference between left and right gaze positions increased over time during the pursuit period for PD but not for NC. The findings were not related to age, as NC and young-adult control group (YC) performed similarly on most of the eye movement measures, and were not correlated with classical measures of PD severity (e.g., Unified Parkinson’s Disease Rating Scale (UPDRS) score).DiscussionOur results suggest that PD may be associated with impairment not only in saccade inhibition, but also in binocular coordination during pursuit, and these aspects of dysfunction may be useful in PD diagnosis or tracking of disease course.

Altered joint kinetic strategies of healthy older adults and individuals with Parkinson’s disease to walk at faster speeds

Individuals with Parkinson’s disease (PD) exhibit poorer walking performance compared to healthy, age-matched adults. Lower extremity joint kinetics may provide insight into this performance deficit but are currently lacking in the PD literature, especially across multiple speeds. The primary purpose of this study was to compare joint kinetics between individuals with PD and healthy older adults at both comfortable and maximal walking speeds. Secondarily, we quantified relationships between joint kinetics and walking speeds within each group. Biomechanical gait analyses were conducted for 13 individuals with PD and 12 age-matched controls during comfortable (CWS) and maximal (MWS) speed walking. Relative contributions to total positive work from the hip, knee, and ankle were compared across groups and speeds. Within each group, relationships between relative joint work and CWS and MWS were also quantified. Significant group by speed interactions indicated that healthy older adults increased hip and decreased ankle relative work at MWS compared to CWS whereas relative work at all joints in PD group remained stable across speeds. In the older group, positive relationships were observed between relative hip work and MWS. In the PD group, negative relationships were observed between relative hip work and CWS and MWS. Healthy older adults disproportionately increased mechanical contributions from the hip at MWS compared to CWS. Individuals with PD did not exhibit similar disproportionate scaling of joint kinetics across speed conditions. Inability to appropriately scale joint kinetics in PD may represent an inflexible neuromuscular system in PD, which may limit walking performance in this population.

Preserved anabolic threshold and capacity as estimated by a novel stable tracer approach suggests no anabolic resistance or increased requirements in weight stable COPD patients

Assessing the ability to respond anabolic to dietary protein intake during illness provides important insight in the capacity of lean body mass maintenance. We applied a newly developed stable tracer approach to assess in one session in patients with chronic obstructive pulmonary disease (COPD) and healthy older adults both the minimal amount of protein intake to obtain protein anabolism (anabolic threshold) and the efficiency of dietary protein to promote protein anabolism (anabolic capacity). We studied 12 clinically and weight stable patients with moderate to very severe COPD (mean±SE forced expiratory volume in 1s: 36±3% of predicted) and 10 healthy age-matched older adults. At 2-h intervals and in consecutive order, all participants consumed a mixture of 0.0, 0.04, 0.10 and 0.30g hydrolyzed casein protein×kg ffm-1×2h-1 and carbohydrates (2:1). We assessed whole body protein synthesis (PS), breakdown (PB), net PS (PS-PB) and net protein balance (phenylalanine (PHE) intake - PHE to tyrosine (TYR) hydroxylation) by IV primed and continuous infusion of L-[ring-2H5]PHE and L-[13C9,15N]-TYR. Anabolic threshold (net protein balance=0) and capacity (slope) were determined on an individual basis from the assumed linear relationship between protein intake and net protein balance. We confirmed a linear relationship between protein intake and net protein balance for all participants (R2 range: 0.9988-1.0, p≤0.0006). On average, the anabolic threshold and anabolic capacity were comparable between the groups (anabolic threshold COPD vs. healthy: 3.82±0.31 vs. 4.20±0.36μmol PHE×kg ffm-1×hr-1; anabolic capacity COPD vs. healthy: 0.952±0.007 and 0.954±0.004). At protein intake around the anabolic threshold (0.04 and 0.10g protein×kg ffm-1×2h-1), the increase in net PS resulted mainly from PB reduction (p<0.0001) whereas at a higher protein intake (0.30g protein×kg ffm-1×2h-1) PS was also stimulated (p<0.0001). The preserved anabolic threshold and capacity in clinically and weight stable COPD patients suggests no disease related anabolic resistance and/or increased protein requirements. ClinicalTrials.gov; No. NCT01734473; URL: www.clinicaltrials.gov.