Effects of chronic low level lead exposure on brain development and function

Abstract Children with congenital heart disease (CHD) are living longer due to effective medical and surgical management. However, the majority have neurodevelopmental delays or disorders. The role of the placenta in fetal brain development is unclear and is the focus of an emerging field known as neuroplacentology. In this review, we summarize neurodevelopmental outcomes in CHD and their brain imaging correlates both in utero and postnatally. We review differences in the structure and function of the placenta in pregnancies complicated by fetal CHD and introduce the concept of a placental inefficiency phenotype that occurs in severe forms of fetal CHD, characterized by a myriad of pathologies. We propose that in CHD placental dysfunction contributes to decreased fetal cerebral oxygen delivery resulting in poor brain growth, brain abnormalities, and impaired neurodevelopment. We conclude the review with key areas for future research in neuroplacentology in the fetal CHD population, including (1) differences in structure and function of the CHD placenta, (2) modifiable and nonmodifiable factors that impact the hemodynamic balance between placental and cerebral circulations, (3) interventions to improve placental function and protect brain development in utero, and (4) the role of genetic and epigenetic influences on the placenta–heart–brain connection. Impact Neuroplacentology seeks to understand placental connections to fetal brain development. In fetuses with CHD, brain growth abnormalities begin in utero. Placental microstructure as well as perfusion and function are abnormal in fetal CHD.

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L2 acquisition of the bei passive in Mandarin Chinese: A constructionist approach

Chinese as a Second Language Research ◽

10.1515/caslar-2020-0007 ◽

2020 ◽

Vol 9 (2) ◽

pp. 169-198

Author(s):

Chen Chen ◽

Feng-hsi Liu

Keyword(s):

Mandarin Chinese ◽

Choice Task ◽

L2 Acquisition ◽

Low Level ◽

Passive Construction ◽

Form And Function ◽

L2 Learners ◽

Constructionist Approach ◽

High Level ◽

And Function

Abstract A major claim in the constructionist approach to language acquisition is that grammar is learned by pairings of form and function. In this study we test this claim by examining how L2 learners of Mandarin Chinese acquire the bei passive construction, a construction that is associated with the meaning of adversity. Our goal is to find out whether L2 learners make the association between the passive and adversity. Participants performed a sentence choice task under four conditions: an adversative context with an adversative verb, an adversative context with a neutral verb, a neutral context with a neutral verb and a positive context with a neutral verb. In each context participants were asked to select either the bei passive construction or its active counterpart. We found that high-level learners consistently chose the bei passive significantly more in adversative contexts than in non-adversative contexts regardless of the connotations of the verbs, while low-level learners made the distinction half of the time. In addition, while low-level learners did not yet associate adversity with the form of the construction, high-level learners did. We conclude that L2 learners do learn the bei passive construction as a form-meaning pair. The constructionist approach is supported.

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Involvement of Thyroid Hormones in Brain Development and Cancer

Cancers ◽

10.3390/cancers13112693 ◽

2021 ◽

Vol 13 (11) ◽

pp. 2693

Author(s):

Gabriella Schiera ◽

Carlo Maria Di Liegro ◽

Italia Di Liegro

Keyword(s):

Nervous System ◽

Thyroid Hormones ◽

Brain Development ◽

Placental Transfer ◽

Regulation Of Gene Expression ◽

Mammalian Brain ◽

Cancer Proliferation ◽

Fetal Thyroid ◽

Genomic Effects ◽

And Function

The development and maturation of the mammalian brain are regulated by thyroid hormones (THs). Both hypothyroidism and hyperthyroidism cause serious anomalies in the organization and function of the nervous system. Most importantly, brain development is sensitive to TH supply well before the onset of the fetal thyroid function, and thus depends on the trans-placental transfer of maternal THs during pregnancy. Although the mechanism of action of THs mainly involves direct regulation of gene expression (genomic effects), mediated by nuclear receptors (THRs), it is now clear that THs can elicit cell responses also by binding to plasma membrane sites (non-genomic effects). Genomic and non-genomic effects of THs cooperate in modeling chromatin organization and function, thus controlling proliferation, maturation, and metabolism of the nervous system. However, the complex interplay of THs with their targets has also been suggested to impact cancer proliferation as well as metastatic processes. Herein, after discussing the general mechanisms of action of THs and their physiological effects on the nervous system, we will summarize a collection of data showing that thyroid hormone levels might influence cancer proliferation and invasion.

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