Publications by authors named "Amy C Barrett"

5 Publications

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Increased Ephrin-B2 expression in pericytes contributes to retinal vascular death in rodents.

Vascul Pharmacol 2020 08 22;131:106761. Epub 2020 Jun 22.

Department of Biomedical Sciences, School of Medicine, Mercer University, Savannah, GA, USA. Electronic address:

Aims: Diabetes-induced retinal vascular cell death aggravates diabetic retinopathy (DR) to the proliferative stage and blindness. Pericytes play a crucial role in retinal capillaries survival, stability, and angiogenesis. Ephrin-B2 is a tyrosine kinase that regulates pericytes/endothelial cells communication during angiogenesis; yet, its role in DR is still unclear. We hypothesize that diabetes increases Ephrin-B2 signaling in pericytes, which contributes to inflammation and retinal vascular cell death.

Methods: Selective inhibition of the Ephrin-B2 expression in the retinal pericytes was achieved using an intraocular injection of adeno-associated virus (AAV) with a specific pericyte promotor. Vascular death was determined by retinal trypsin digest. Pathological angiogenesis was assessed using the oxygen-induced retinopathy model in pericyte-Ephrin-B2 knockout mice, wild type, and wild type injected with AAV. Angiogenic properties, inflammatory, and apoptotic markers were measured in human retinal pericytes (HRP) grown under diabetic conditions.

Key Finding: Diabetes significantly increased the expression of Ephrin-B2, inflammatory, and apoptotic markers in the diabetic retinas and HRP. These effects were prevented by silencing Ephrin-B2 in HRP. Moreover, Ephrin-B2 silencing in retinal pericytes decreased pathological angiogenesis and acellular capillaries formation in diabetic retinas.

Significance: Increased Ephrin-B2 expression in the pericytes contributed to diabetes-induced retinal inflammation and vascular death. These results identify pericytes-Ephrin-B2 as a therapeutic target for DR.
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http://dx.doi.org/10.1016/j.vph.2020.106761DOI Listing
August 2020

The Use of Eye Tracking as a Biomarker of Treatment Outcome in a Pilot Randomized Clinical Trial for Young Children with Autism.

Autism Res 2019 05 20;12(5):779-793. Epub 2019 Mar 20.

Department of Counseling, Clinical, and School Psychology, University of California Santa Barbara, Santa Barbara, California.

There is a pressing need for objective, quantifiable outcome measures in intervention trials for children with autism spectrum disorder (ASD). The current study investigated the use of eye tracking as a biomarker of treatment response in the context of a pilot randomized clinical trial of treatment for young children with ASD. Participants included 28 children with ASD, aged 18-48 months, who were randomized to one of two conditions: Pivotal Response Intervention for Social Motivation (PRISM) or community treatment as usual (TAU). Eye-tracking and behavioral assessment of developmental functioning were administered at Time 1 (prior to randomization) and at Time 2 (after 6 months of intervention). Two well-established eye-tracking paradigms were used to measure social attention: social preference and face scanning. As a context for understanding relationships between social attention and developmental ability, we first examined how scanning patterns at Time 1 were associated with concurrent developmental functioning and compared to those of 23 age-matched typically developing (TD) children. Changes in scanning patterns from Time 1 to Time 2 were then compared between PRISM and TAU groups and associated with behavioral change over time. Results showed that the social preference paradigm differentiated children with ASD from TD children. In addition, attention during face scanning was associated with language and adaptive communication skills at Time 1 and change in language skills from Time 1 to Time 2. These findings highlight the importance of examining targeted biomarkers that measure unique aspects of child functioning and that are well-matched to proposed mechanisms of change. Autism Research 2019, 12: 779-793. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Biomarkers have the potential to provide important information about how and why early interventions effect positive change for young children with ASD. The current study suggests that eye-tracking measures of social attention can be used to track change in specific areas of development, such as language, and points to the need for targeted eye-tracking paradigms designed to measure specific behavioral changes. Such biomarkers could inform the development of optimal, individualized, and adaptive interventions for young children with ASD.
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http://dx.doi.org/10.1002/aur.2093DOI Listing
May 2019

A Pilot Randomized Clinical Trial of an Enhanced Pivotal Response Treatment Approach for Young Children with Autism: The PRISM Model.

J Autism Dev Disord 2019 Jun;49(6):2358-2373

University of California Santa Barbara, Santa Barbara, CA, USA.

The symptoms of autism spectrum disorder are conceptualized to alter the quality of parent-children interactions, exposure to social learning exchanges, and ultimately the course of child development. There is evidence that modifying the procedures of Pivotal Response Treatment (PRT) to explicitly target social motivation enhances child engagement and parent-child synchrony in moment-by-moment exchanges. However, it is unclear if these within session improvements ultimately yield favorable developmental outcomes over time. The current investigation presents feasibility, utility, and preliminary efficacy data of a pilot randomized clinical trial (RCT) of a Pivotal Response Intervention for Social Motivation (PRISM) model. Data on participant factors, treatment protocol acceptability, and outcome variance and effect size are highly favorable and support the pursuit of a future, large scale RCT.
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http://dx.doi.org/10.1007/s10803-019-03909-1DOI Listing
June 2019

Inhibition of Ephrin-B2 in brain pericytes decreases cerebral pathological neovascularization in diabetic rats.

PLoS One 2019 8;14(1):e0210523. Epub 2019 Jan 8.

Biomedical Sciences Department, School of Medicine, Mercer University, Savannah, Georgia, United States of America.

We have previously shown that diabetes causes dysfunctional cerebral neovascularization that increases the risk for cerebrovascular disorders such as stroke and cognitive impairment. Pericytes (PCs) play a pivotal role in the angiogenic process through their interaction with the endothelial cells (EC). Yet, the role of PCs in dysfunctional cerebral neovascularization in diabetes is unclear. In the present study, we tested the hypothesis that the increased proangiogenic Ephrin-B2 signaling in PCs contributes to the dysfunctional cerebral neovascularization in diabetes. Type-II diabetes was induced by a combination of high fat diet and low dose streptozotocin injection in male Wistar rats. Selective in vivo Ephrin-B2 silencing in brain PCs was achieved using the stereotactic injection of adeno-associated virus (AAV) with NG2-promoter that expresses Ephrin-B2 shRNA. Neovascularization was assessed using vascular fluorescent dye stain. Novel object recognition (NOR) test was used to determine cognitive functions. Human brain microvascular pericytes HBMVPCs were grown in high glucose 25 mM and palmitate 200 uM (HG/Pal) to mimic diabetic conditions. Scratch migration and tube formation assays were conducted to evaluate PC/EC interaction and angiogenic functions in PC/EC co-culture. Diabetes increased the expression of Ephrin-B2 in the cerebrovasculature and pericytes. Concomitant increases in cerebral neovascularization parameters including vascular density, tortuosity and branching density in diabetic rats were accompanied by deterioration of cognitive function. Inhibition of Ephrin-B2 expression in PCs significantly restored cerebral vascularization and improved cognitive functions. HG/Pal increased PC/EC angiogenic properties in co-culture. Silencing Ephrin-B2 in PCs significantly reduced PC migration and PC/EC co-culture angiogenic properties. This study emphasizes the significant contribution of PCs to the pathological neovascularization in diabetes. Our findings introduce Ephrin-B2 signaling as a promising therapeutic target to improve cerebrovascular integrity in diabetes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0210523PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6324788PMC
November 2019

A Randomized Controlled Trial of the Social Tools And Rules for Teens (START) Program: An Immersive Socialization Intervention for Adolescents with Autism Spectrum Disorder.

J Autism Dev Disord 2018 03;48(3):892-904

Koegel Autism Center, Department of Counseling, Clinical, and School Psychology, Gevirtz Graduate School of Education, University of California Santa Barbara, Santa Barbara, CA, 93106-9490, USA.

Adolescents with ASD face numerous personal and contextual barriers that impede the development of social motivation and core competencies, warranting the need for targeted intervention. A randomized controlled trial was conducted with 40 adolescents to evaluate the merits of a multi-component socialization intervention that places emphasis on experiential learning. This investigation evaluated the impact of the 20-week START program on the social functioning of adolescents with ASD. Significant Group × Time differences between START and waitlist control groups were found across multiple measures. Secondary analyses of the entire program cohort also yielded significant improvement trends across all measures. These findings may be an important step in identifying optimal strategies to target the complex factors limiting optimal social development in ASD.
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http://dx.doi.org/10.1007/s10803-017-3380-1DOI Listing
March 2018