Distinctive neural correlates of phonological and reading impairment in fetal alcohol-exposed adolescents with and without facial dysmorphology

Unbound Fractions of PFAS in Human and Rodent Tissues: Rat Liver a Suitable Proxy for Evaluating Emerging PFAS?

Adverse health effects associated with exposures to perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a concern for public health and are driven by their elimination half-lives and accumulation in specific tissues. However, data on PFAS binding in human tissues are limited. Accumulation of PFAS in human tissues has been linked to interactions with specific proteins and lipids in target organs. Additional data on PFAS binding and unbound fractions (funbound) in whole human tissues are urgently needed. Here, we address this gap by using rapid equilibrium dialysis to measure the binding and funbound of 16 PFAS with 3 to 13 perfluorinated carbon atoms (ηpfc = 3-13) and several functional headgroups in human liver, lung, kidney, heart, and brain tissue. We compare results to mouse (C57BL/6 and CD-1) and rat tissues. Results show that funbound decreases with increasing fluorinated carbon chain length and hydrophobicity. Among human tissues, PFAS binding was generally greatest in brain > liver ≈ kidneys ≈ heart > lungs. A correlation analysis among human and rodent tissues identified rat liver as a suitable surrogate for predicting funbound for PFAS in human tissues (R2 ≥ 0.98). The funbound data resulting from this work and the rat liver prediction method offer input parameters and tools for toxicokinetic models for legacy and emerging PFAS.

Species-Specific Unbound Fraction Differences in Highly Bound PFAS: A Comparative Study across Human, Rat, and Mouse Plasma and Albumin

Per- and polyfluoroalkyl substances (PFAS) are a diverse group of fluorinated compounds which have yet to undergo comprehensive investigation regarding potential adverse health effects and bioaccumulative properties. With long half-lives and accumulative properties, PFAS have been linked to several toxic effects in both non-clinical species such as rat and mouse as well as human. Although biological impacts and specific protein binding of PFAS have been examined, there is no study focusing on the species-specific fraction unbound (fu) in plasma and related toxicokinetics. Herein, a presaturation equilibrium dialysis method was used to measure and validate the binding of 14 individual PFAS with carbon chains containing 4 to 12 perfluorinated carbon atoms and several functional head-groups to albumin and plasma of mouse (C57BL/6 and CD-1), rat, and human. Equivalence testing between each species-matrix combination showed positive correlation between rat and human when comparing fu in plasma and binding to albumin. Similar trends in binding were also observed for mouse plasma and albumin. Relatively high Spearman correlations for all combinations indicate high concordance of PFAS binding regardless of matrix. Physiochemical properties of PFAS such as molecular weight, chain length, and lipophilicity were found to have important roles in plasma protein binding of PFAS.

The interaction of genetic sex and prenatal alcohol exposure on health across the lifespan

Prenatal alcohol exposure (PAE) can reprogram the development of cells and tissues, resulting in a spectrum of physical and neurobehavioral teratology. PAE immediately impacts fetal growth, but its effects carry forward post-parturition, into adolescence and adulthood, and can result in a cluster of disabilities, collectively termed Fetal Alcohol Spectrum Disorders. Emerging preclinical and clinical research investigating neurological and behavioral outcomes in exposed offspring point to genetic sex as an important modifier of the effects of PAE. In this review, we discuss the literature on sex differences following PAE, with studies spanning the fetal period through adulthood, and highlight gaps in research where sex differences are likely, but currently under-investigated. Understanding how sex and PAE interact to affect offspring health outcomes across the lifespan is critical for identifying the full complement of PAE-associated secondary conditions, and for refining targeted interventions to improve the quality of life for individuals with PAE.

Arcuate fasciculus and pre-reading language development in children with prenatal alcohol exposure

Introduction

Prenatal alcohol exposure (PAE) contributes to widespread neurodevelopmental challenges, including reading, and has been associated with altered white matter. Here, we aimed to investigate whether arcuate fasciculus (AF) development is associated with pre-reading language skills in young children with PAE.

Methods

A total of 51 children with confirmed PAE (25 males; 5.6 ± 1.1 years) and 116 unexposed controls (57 males; 4.6 ± 1.2 years) underwent longitudinal diffusion tensor imaging (DTI), for a total of 111 scans from participants with PAE and 381 scans in the unexposed control group. We delineated the left and right AF and extracted mean fractional anisotropy (FA) and mean diffusivity (MD). Pre-reading language ability was assessed using age-standardized phonological processing (PP) and speeded naming (SN) scores of the NEPSY-II. Linear mixed effects models were run to determine the relationship between diffusion metrics and age, group, sex, and age-by-group interactions, with subject modeled as a random factor. A secondary mixed effect model analysis assessed the influence of white matter microstructure and PAE on pre-reading language ability using diffusion metric-by-age-by-group interactions, with 51 age- and sex-matched unexposed controls.

Results

Phonological processing (PP) and SN scores were significantly lower in the PAE group (p < 0.001). In the right AF, there were significant age-by-group interactions for FA (p < 0.001) and MD (p = 0.0173). In the left AF, there was a nominally significant age-by-group interaction for MD that failed to survive correction (p = 0.0418). For the pre-reading analysis, a significant diffusion-by-age-by-group interaction was found for left FA (p = 0.0029) in predicting SN scores, and for the right FA (p = 0.00691) in predicting PP scores.

Discussion

Children with PAE showed altered developmental trajectories for the AF, compared with unexposed controls. Children with PAE, regardless of age, showed altered brain-language relationships that resembled those seen in younger typically developing children. Our findings support the contention that altered developmental trajectories in the AF may be associated with functional outcomes in young children with PAE.

Frontoparietal and temporal white matter diffusion MRI in children and youth with prenatal alcohol exposure

BACKGROUND

Prenatal alcohol exposure (PAE) is associated with brain alterations and neurocognitive deficits, but relationships between brain alterations and neurocognitive deficits remain unclear.

METHODS

Diffusion tensor imaging (DTI) data were obtained from 31 participants with PAE and 31 unexposed controls aged 7-15 years. Mean diffusivity (MD) and fractional anisotropy (FA) were derived from the genu, body, and splenium of the corpus callosum (CC), bilateral cingulum, and inferior and superior longitudinal fasciculus (ILF, SLF). Participants completed language subtests from the NEPSY-II. Executive functioning was measured using the Behavior Rating Inventory of Executive Functioning (BRIEF-PR) and verbal learning was assessed using the California Verbal Learning Test-Children's Version (CVLT-C) only in children with PAE. Group differences in diffusion metrics and cognitive scores were tested. Principal component analysis was used to reduce redundancy in cognitive and behavior variables; associations between components and brain measures were then assessed.

RESULTS

Children with PAE had lower MD in the right SLF compared with unexposed controls. FA was positively related to age in 6 of 9 tracts and MD negatively related to age in all tracts; there were no significant age-by-group interactions. Participants with PAE scored lower than unexposed peers on the NEPSY-II Comprehension of Instructions and Phonological Processing and above population norms (indicating worse performance) on the BRIEF-PR. Children with PAE had a negative association between a principal component closely associated with Speeded Naming and FA in the left SLF (PAE: p = 0.002) and left ILF (PAE: p = 0.002); unexposed controls showed no significant associations.

CONCLUSION

We found widespread cognitive difficulties in children with PAE, but relatively limited differences in brain metrics and associations with age. Different brain-cognitive relationships were found in children with PAE compared with controls. Overall, the results provide additional evidence that PAE may lead to cognitive difficulties and disrupt typical brain-function relationships.