Prevalence and risk factors of adverse birth outcomes in the Pacific Island region: a scoping review protocol

Introduction

Fetal growth restriction, preterm birth, low birth weight and stillbirth are adverse birth outcomes that are prevalent in low-income and middle-income settings such as the Pacific Island region. It is widely accepted that the excess burden of adverse birth outcomes is attributable to socioeconomic and environmental factors that predispose families to excess risk. Our review seeks to determine the prevalence of adverse birth outcomes in the Pacific Island region and to identify the risk factors of adverse birth outcomes in the Pacific Island region.

Methods

This scoping review will follow the five-staged Arksey and O’Malley’s framework and consultation with Solomon Islands’ health stakeholders. A preliminary literature review was undertaken to understand the scope of the review. We will use Medical Subject Heading and keyword terms for adverse birth outcomes to search CINAHL, Medline, Scopus, ProQuest and Springer Link databases for articles published from 1 January 2000. The subsequent searches will be undertaken via Google Scholar and the internet browser to world health organisation and regional health organisations for published and unpublished reports on non-indexed studies. All articles retrieved will be managed with EndNote software. Eligible studies will be screened using Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow chart for final selection. In the charting phase, we will extract the data into Excel spreadsheets. The results will be presented as numerical and thematic summaries that map risk factors and prevalence to the population and cultures of the Pacific Island region.

Ethics and dissemination

Formal ethical approval is not required as primary or administrative data will not be collected. However, we will seek ethics approval for the stakeholder consultation from the Research Office of Curtin University and the Solomon Islands. The findings of this study will be published in peer-reviewed journals and presented in national and regional conferences and disseminated to stakeholders.

Ethics approval

There will be no direct contact with human or patients in the case of the scoping review; therefore, no ethics will be required. However, we will seek ethical approval from the Research Ethics Office of Curtin University and the Health Research and Ethics Committee in the Solomon Islands for stakeholder consultation. Dissemination will be made through regional conferences and publication in peer-reviewed journals.

Establishment and cryptic transmission of Zika virus in Brazil and the Americas

Transmission of Zika virus (ZIKV) in the Americas was first confirmed in May 2015 in northeast Brazil. Brazil has had the highest number of reported ZIKV cases worldwide (more than 200,000 by 24 December 2016) and the most cases associated with microcephaly and other birth defects (2,366 confirmed by 31 December 2016). Since the initial detection of ZIKV in Brazil, more than 45 countries in the Americas have reported local ZIKV transmission, with 24 of these reporting severe ZIKV-associated disease. However, the origin and epidemic history of ZIKV in Brazil and the Americas remain poorly understood, despite the value of this information for interpreting observed trends in reported microcephaly. Here we address this issue by generating 54 complete or partial ZIKV genomes, mostly from Brazil, and reporting data generated by a mobile genomics laboratory that travelled across northeast Brazil in 2016. One sequence represents the earliest confirmed ZIKV infection in Brazil. Analyses of viral genomes with ecological and epidemiological data yield an estimate that ZIKV was present in northeast Brazil by February 2014 and is likely to have disseminated from there, nationally and internationally, before the first detection of ZIKV in the Americas. Estimated dates for the international spread of ZIKV from Brazil indicate the duration of pre-detection cryptic transmission in recipient regions. The role of northeast Brazil in the establishment of ZIKV in the Americas is further supported by geographic analysis of ZIKV transmission potential and by estimates of the basic reproduction number of the virus.

Gene expression of T3-regulated genes in a mouse model of the human thyroid hormone resistance

AIMS

To understand how thyroid hormone (TH) regulates tissue-specific gene expression in patients with the syndrome of resistance to TH (RTHβ), we used a mouse model that replicates the human RTHβ, specifically the ∆337T mutation in the thyroid hormone receptor β (THRβ).

MAIN METHODS

We investigated the expression of key TH target genes in the pituitary and liver of TRβ^∆337T and wild type THRβ mice by qPCR before and after a T₃ suppression test consisting of the administration of increasing concentrations of T₃ to hypothyroid mice.

KEY FINDINGS

Pituitary Tshb and Cga expression decreased and Gh expression increased in TRβ^∆337T mice after T₃ suppression. The stimulation of positively regulated TH genes was heterogeneous in the liver. Levels of liver Me1 and Thsrp were elevated in TRβ^∆337T mice after T₃ administration. Slc16a2 and Gpd2 did not respond to T₃ stimulation in the liver of TRβ^∆337T mice whereas Dio1 response was lower than that observed in WT mice. Moreover, although Chdh and Upd1 genes were negatively regulated in the liver, the expression of these genes was elevated after T₃ suppression. We did not observe significant changes in THRα expression in the liver and pituitary, while THRβ levels were diminished in the pituitary and increased in the liver.

SIGNIFICANCE

Using a model expressing a THRβ unable to bind T3, we showed the expression pattern of liver negative and positive regulated genes by T3.

Thyroid hormone and estradiol have overlapping effects on kidney glutathione S-transferase-α gene expression

α-Class GST (Gsta) represents an essential component of cellular antioxidant defense mechanisms in both the liver and the kidney. Estrogens and thyroid hormones (TH) play central roles in animal development, physiology, and behavior. Evidence of the overlapping functions of thyroid hormones and estrogens has been shown, although the molecular mechanisms are not always clear. We evaluated an interaction between TH and estradiol in regulating kidney Gsta expression and function. First, we observed that female mice expressed greater amounts of Gsta compared with males and showed an opposite pattern of expression in TRβ knock-in mice. To further investigate these sex differences, hypothyroidism was induced by a 5-propyl-2-thiouracil diet, and hyperthyroidism was induced by daily T₃ injections. Hypothyroidism increased kidney Gsta expression in male mice but not in female mice, indicating that sex hormones could be influencing the regulation of Gsta by thyroid hormones. To analyze this hypothesis, ovariectomized females were subjected to hypo- and hyperthyroidism, which led to a male profile of Gsta expression. When hypo- or hyperthyroid ovariectomized mice were treated with 17β-estradiol benzoate, we were able to confirm that estradiol was interfering with TH modulation; Gsta expression is increased by T₃ when estradiol is present and decreased by T₃ when estradiol is absent. Using proximal tubule cells, we also showed that estradiol and T₃ worked together to modulate Gsta expression in an overlapping fashion. In summary, 1) the sex difference in the basal expression of Gsta impacts the detoxification process, 2) kidney Gsta expression is regulated by TH in males and females but in opposite directions, and 3) T₃ and estradiol interact directly in renal proximal cells to regulate Gsta expression in females.