1,623 research outputs found

    The Mediating Role of Processing Speed in Reading-Related White Matter Tracts and Word Reading Skills of Adult Survivors of Childhood Brain Tumor

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    The purpose of this study was to investigate the relationship between word reading and white matter (WM) integrity in the reading system and test a theory-based moderated mediation model such that relationship of WM integrity with word reading is mediated by processing speed and indirect effect is moderated by group. Thirty-seven adult survivors of childhood brain tumor and typically developing adults participated (mean age=24.19(4.51) years, 62% female). Tractography identified the WM tract for three reading system connections. Fractional anisotropy of the IFOF and PT-OT tracts were significantly correlated with word reading in survivors (r=.55, .46, respectively;

    Corpus Callosum and Word Reading in Adult Survivors of Childhood Posterior Fossa Tumors

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    Adult survivors of childhood posterior fossa tumors can experience reading difficulties related to white matter integrity. Previously, reading was shown to be related to cortical white matter tracts, however information transfer across the corpus callosum (CC) may also play a role in reading. The current study used both macro- and microstructural measures of the WM structure of the corpus callosum. The current study examined how white matter volume and fractional anisotropy (FA) in five divisions of the CC was related to degree of neurological risk and reading skill, and tested two mediation models predicting reading. Participants included 20 adult survivors of childhood posterior fossa tumor and 23 healthy controls. Volume and FA were measured in five divisions of the mid-sagittal corpus callosum. Total intracranial vault was used as a covariate in volume analyses. FA was reduced in CC1 and volume was reduced in each subregion in survivors. Volume but not FA was related to degree of neurological risk. Results identified that reduced volume in CC1 and CC5, and FA in CC5 appear to be specifically related to reading skill in line with the cortical reading regions that connect in these subregions of the CC. Mediation models indicate that processing speed is the mechanism by which volume is related to reading skill. These findings have implications for addressing processing speed in reading interventions in survivors and provide insight into the interhemispheric connections in the reading network

    Reading Skill in Adult Survivors of Childhood Brain Tumor: A Theory-Based Neurocognitive Model

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    Objective: This study investigated the relationship between word reading and white matter (WM) integrity within a neuroanatomical-based reading system comparing adult survivors of childhood brain tumors and controls. It was predicted that the association between WM integrity and word reading would be mediated by processing speed, and this indirect effect would be moderated by group. Method: Thirty-seven adult survivors of childhood brain tumor and typically developing adults participated (age M=24.19±4.51 years, 62% female). DTI Tractography identified the WM tract for three of the reading system connections: inferior fronto-occipital fasciculus (IFOF), arcuate fasciculus (AF), and parietotemporal-occipitotemporal connection (PT-OT). Results:Fractional anisotropy values (FA) of the PT-OT tract were significantly correlated with word reading in survivors and controls (r=.45, .58, respectively; p Conclusion: Results suggest the tracts emerging from the occipitotemporal area are a critical component of the reading system in adults. The finding that processing speed was the mechanism by which WM was associated with reading in survivors is in alignment with the developmental cascade model. Current findings bolster the existing theory-based models of reading using innovative diffusion tensor imaging and moderated mediation statistical neurodevelopmental model, establishing the role of processing speed and specific WM pathway integrity in word reading skill

    The Importance of the Northeastern Gulf of Mexico to Foraging Loggerhead Sea Turtles

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    Identification of high-use foraging sites where imperiled sea turtles are resident remains a globally-recognized conservation priority. In the biodiverse Gulf of Mexico (GoM), recent telemetry studies highlighted post-nesting foraging sites for federally threatened loggerhead turtles (Caretta caretta). Our aim here was to discern loggerhead use of additional northern GoM regions that may serve as high-use foraging sites. Thus, we used satellite tracking and switching state-space modeling to show that the Big Bend region off the northwest Florida coast is a coastal foraging area that supports imperiled adult female loggerhead turtles tracked from different nesting subpopulations. From 2011 to 2016, we satellite-tagged 15 loggerheads that nested on four distinct beaches around the GoM: Dry Tortugas National Park, FL; Everglades National Park, FL; St. Joseph Peninsula, FL; and Gulf Shores, AL. Turtles arrived at their foraging ground in the Big Bend region between June and September and remained resident in their respective foraging sites for an average of 198 tracking days, where they established mean home ranges (95% kernel density estimate) 232.7 km2. Larger home ranges were in deeper water; 50% kernel density estimate centroid values were a mean 26.4 m deep and 52.7 km from shore. The Big Bend region provides a wide area of suitable year-round foraging habitat for loggerheads from at least 3 different nesting subpopulations. Understanding where and when threatened loggerheads forage and remain resident is key for designing both surveys of foraging resources and additional protection strategies that can impact population recovery trajectories for this imperiled species

    Stable isotopes used to infer trophic position of green turtles (Chelonia mydas) from Dry Tortugas National Park, Gulf of Mexico, United States

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    Evaluating resource use patterns for imperiled species is critical for understanding what supports their populations. Here we established stable isotope (δ13C, δ15N) values for the endangered green sea turtle (Chelonia mydas) population found within the boundaries of Dry Tortugas National Park (DRTO), south Florida, USA. There is little gene flow between turtles sampled at DRTO and in other rookeries in Florida, underscoring the need to study this distinct population. Between 2008 and 2015 we collected multiple sample types (skin [homogenized epidermis/dermis], whole blood, red blood cells, plasma, carapace) from 151 unique green turtles, including 43 nesting females and 108 in-water captures; some individuals were resampled multiple times across years to evaluate consistency of isotope signatures. Isotopic ratios ranged from -27.3 to -5.4 for δ13C and 3.7 to 10.6 for δ15N. Using linear mixed models, we evaluated covariates (sample type, turtle size and year) that best explained the isotope patterns observed in turtle tissues. Predictions from the top model for δ13C indicated a slight decrease over time and for δ15N a slight increase in the middle sampling years (2010–2012); results indicated that turtle size appeared to be the driver behind the range in δ13C and δ15N observed in turtle skin. We found a pattern in stable carbon isotope values that are indicative of an ontogenetic change from an omnivorous diet in smaller turtles to a seagrass-based diet in larger turtles. When we compared the stable carbon and nitrogen isotope values of the samples collected from turtles with that of seagrasses found in DRTO, we found that turtles \u3e 65 cm SCL had similar stable carbon isotope values to the seagrass species present. Results of this study suggest stable isotope analysis coupled with data for available resources can be useful for tracking and detecting future changes in green turtle resource shifts in DRTO

    Variability of Urinary Phthalate Metabolite and Bisphenol A Concentrations before and during Pregnancy

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    Background: Gestational phthalate and bisphenol A (BPA) exposure may increase the risk of adverse maternal/child health outcomes, but there are few data on the variability of urinary biomarkers before and during pregnancy

    Organizational culture and climate as moderators of enhanced outreach for persons with serious mental illness: results from a cluster-randomized trial of adaptive implementation strategies

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    Abstract Background Organizational culture and climate are considered key factors in implementation efforts but have not been examined as moderators of implementation strategy comparative effectiveness. We investigated organizational culture and climate as moderators of comparative effectiveness of two sequences of implementation strategies (Immediate vs. Delayed Enhanced Replicating Effective Programs [REP]) combining Standard REP and REP enhanced with facilitation on implementation of an outreach program for Veterans with serious mental illness lost to care at Veterans Health Administration (VA) facilities nationwide. Methods This study is a secondary analysis of the cluster-randomized Re-Engage implementation trial that assigned 3075 patients at 89 VA facilities to either the Immediate or Delayed Enhanced REP sequences. We hypothesized that sites with stronger entrepreneurial culture, task, or relational climate would benefit more from Enhanced REP than Standard REP. Veteran- and site-level data from the Re-Engage trial were combined with site-aggregated measures of entrepreneurial culture and task and relational climate from the 2012 VA All Employee Survey. Longitudinal mixed-effects logistic models examined whether the comparative effectiveness of the Immediate vs. Delayed Enhanced REP sequences were moderated by culture or climate measures at 6 and 12 months post-randomization. Three Veteran-level outcomes related to the engagement with the VA system were assessed: updated documentation, attempted contact by coordinator, and completed contact. Results For updated documentation and attempted contact, Veterans at sites with higher entrepreneurial culture and task climate scores benefitted more from Enhanced REP compared to Standard REP than Veterans at sites with lower scores. Few culture or climate moderation effects were detected for the comparative effectiveness of the full sequences of implementation strategies. Conclusions Implementation strategy effectiveness is highly intertwined with contextual factors, and implementation practitioners may use knowledge of contextual moderation to tailor strategy deployment. We found that facilitation strategies provided with Enhanced REP were more effective at improving uptake of a mental health outreach program at sites with stronger entrepreneurial culture and task climate; Veterans at sites with lower levels of these measures saw more similar improvement under Standard and Enhanced REP. Within resource-constrained systems, practitioners may choose to target more intensive implementation strategies to sites that will most benefit from them. Trial registration ISRCTN: ISRCTN21059161 . Date registered: April 11, 2013.https://deepblue.lib.umich.edu/bitstream/2027.42/144775/1/13012_2018_Article_787.pd
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