Effects of Exercise Intensity on Acute Circulating Molecular Responses Poststroke.

Background. Exercise intensity can influence functional recovery after stroke, but the mechanisms remain poorly understood. Objective. In chronic stroke, an intensity-dependent increase in circulating brain-derived neurotrophic factor (BDNF) was previously found during vigorous exercise. Using the same serum samples, this study tested acute effects of exercise intensity on other circulating molecules related to neuroplasticity, including vascular-endothelial growth factor (VEGF), insulin-like growth factor-1 (IGF1), and cortisol, with some updated analyses involving BDNF. Methods. Using a repeated-measures design, 16 participants with chronic stroke performed 3 exercise protocols in random order: treadmill high-intensity interval training (HIT-treadmill), seated-stepper HIT (HIT-stepper), and treadmill moderate-intensity continuous exercise (MCT-treadmill). Serum molecular changes were compared between protocols. Mediation and effect modification analyses were also performed. Results. VEGF significantly increased during HIT-treadmill, IGF1 increased during both HIT protocols and cortisol nonsignificantly decreased during each protocol. VEGF response was significantly greater for HIT-treadmill versus MCT-treadmill when controlling for baseline. Blood lactate positively mediated the effect of HIT on BDNF and cortisol. Peak treadmill speed positively mediated effects on BDNF and VEGF. Participants with comfortable gait speed ≥0.4 m/s had significantly lower VEGF and higher IGF1 responses, with a lower cortisol response during MCT-treadmill. Conclusions. BDNF and VEGF are promising serum molecules to include in future studies testing intensity-dependent mechanisms of exercise on neurologic recovery. Fast training speed and anaerobic intensity appear to be critical ingredients for eliciting these molecular responses. Serum molecular response differences between gait speed subgroups provide a possible biologic basis for previously observed differences in training responsiveness.

Functional Reach, Depression Scores, and Number of Medications Are Associated With Number of Falls in People With Chronic Stroke.

BACKGROUND: Falls are a common adverse event among people with stroke. Previous studies investigating risk of falls after stroke have relied primarily on retrospective fall history ranging from 6-12 months recall, with inconsistent findings. OBJECTIVES: To identify factors and balance assessment tools that are associated with number of falls in individuals with chronic stroke. DESIGN: Secondary analysis of a randomized clinical trial. SETTING: Multisite academic and clinical institutions. PARTICIPANTS: Data from 181 participants with stroke (age 60.67 ± 11.77 years, post stroke 4.51 ± 4.78 years) were included. METHODS: Study participants completed baseline testing and were prospectively asked about falls. A multivariate negative binomial regression was used to identify baseline predictive factors predicting falls: age, endurance (6 minute walk test), number of medications, motor control (Fugl-Meyer lower extremity score), depression (Patient Health Questionnaire-9), physical activity (number of steps per week), and cognition (Mini Mental Status Exam score). A second negative binomial regression analysis was used to identify baseline balance assessment scores predicting falls: gait velocity (comfortable 10 Meter Walk), Berg Balance Scale (BBS), Timed Up and Go (TUG), and Functional Reach Test (FRT). Receiver operating characteristic (ROC) and area under the curve (AUC) were used to determine the cutoff scores for significant predictors of recurrent falls. MAIN OUTCOME MEASUREMENT: The number of falls during the 42-week follow-up period. RESULTS: Baseline measures that significantly predicted the number of falls included increased number of medications, higher depression scores, and decreased FRT. Cutoff scores for the number of medications were 8.5 with an AUC of 0.68. Depression scores differentiated recurrent fallers at a threshold of 2.5 scores with an AUC of 0.62. FRT differentiated recurrent fallers at a threshold of 18.15 cm with an AUC of 0.66. CONCLUSIONS: Number of medications, depression scores, and decreased FRT distance at baseline were associated with increased number of falls. Increased medications might indicate multiple comorbidities or polypharmacy effect; increased depression scores may indicate psychological status; and decreased functional reach distance could indicate dynamic balance impairments. LEVEL OF EVIDENCE: II.

HRCT/CT and associated spirometric effects of low Libby amphibole asbestos exposure.

OBJECTIVE: Evaluate the relationship between cumulative fiber exposure and high-resolution or conventional chest computed tomography (HRCT/CT) changes and spirometry of workers with Libby amphibole asbestos exposure. METHODS: Of the original 1980 cohort (n = 513), 431 were living and asked to participate. Images were evaluated for localized pleural thickening (LPT), diffuse pleural thickening (DPT), and parenchymal changes. RESULTS: A total of 306 participants provided either HRCT/CT scans (n = 191) or chest radiographs (n = 115). Of the 191 with HRCT/CT, 52.9% had pleural changes and 13.1% had parenchymal changes. Those with LPT only, LPT and/or DPT, or DPT and/or parenchymal changes had mean 6.1, 8.0, and 18.0 loss in percent predicted forced vital capacity, respectively. CONCLUSIONS: Exposure to vermiculite containing amphibole fibers is associated with pleural and parenchymal HRCT/CT changes at low cumulative fiber exposure; these changes are associated with spirometric decrements.

Asbestos-related radiographic findings among household contacts of workers exposed to Libby vermiculite: impact of workers' personal hygiene practices.

OBJECTIVE: To explore the potential impact of worker hygiene by determining the prevalence of radiographic changes consistent with asbestos exposure among household contacts of workers exposed to Libby vermiculite that contained amphibole fibers. METHODS: Workers and household contacts had chest radiographs and completed questionnaires regarding hygiene and potential exposure pathways. RESULTS: Participants included 191 household contacts of 118 workers. One household contact (0.5%) had localized pleural thickening, and three (1.6%) had irregular opacities at profusion category 1/0 or greater. Worker radiographs demonstrated pleural changes in 45% and irregular opacities at profusion category 1/0 or greater in 8%. CONCLUSIONS: Libby vermiculite-exposed workers demonstrated an elevated prevalence of pleural and interstitial chest radiographic changes. There was, however, no increased prevalence of similar changes among household contacts, likely because of personal hygiene measures taken by the majority of workers.

Mesothelioma associated with commercial use of vermiculite containing Libby amphibole.

OBJECTIVES: To describe asbestos-related mortality among manufacturing workers who expanded and processed Libby vermiculite that contained amphibole fiber. METHODS: Standardized mortality ratio was calculated for 465 white male workers 31 years after last Libby vermiculite exposure. RESULTS: Two workers died from mesothelioma, resulting in a significantly increased standardized mortality ratio of 10.5 (95% confidence interval, 1.3 to 38.0). These workers were in the upper 10th percentile of cumulative fiber exposure, that is, 43.80 and 47.23 fiber-years/cm, respectively. One additional worker with cumulative fiber exposure of 5.73 fiber-years/cm developed mesothelioma but is not deceased. There were no other significantly increased standardized mortality ratios. CONCLUSIONS: Workers expanding and processing Libby vermiculite in a manufacturing setting demonstrated an increased risk for the development of mesothelioma following exposure to the amphibole fiber contained within this vermiculite ore source.

Cancer risk among firefighters: a review and meta-analysis of 32 studies.

OBJECTIVE: The objective of this study was to review 32 studies on firefighters and to quantitatively and qualitatively determine the cancer risk using a meta-analysis. METHODS: A comprehensive search of computerized databases and bibliographies from identified articles was performed. Three criteria used to assess the probable, possible, or unlikely risk for 21 cancers included pattern of meta-relative risks, study type, and heterogeneity testing. RESULTS: The findings indicated that firefighters had a probable cancer risk for multiple myeloma with a summary risk estimate (SRE) of 1.53 and 95% confidence interval (CI) of 1.21-1.94, non-Hodgkin lymphoma (SRE = 1.51, 95% CI = 1.31-1.73), and prostate (SRE = 1.28; 95% CI = 1.15-1.43). Testicular cancer was upgraded to probable because it had the highest summary risk estimate (SRE = 2.02; 95% CI = 1.30-3.13). Eight additional cancers were listed as having a "possible" association with firefighting. CONCLUSIONS: Our results confirm previous findings of an elevated metarelative risk for multiple myeloma among firefighters. In addition, a probable association with non-Hodgkin lymphoma, prostate, and testicular cancer was demonstrated.