Endotoxin-induced cerebral pathophysiology: differences between fetus and newborn

Developmental priming of early cerebrovascular ageing: Implications across a lifetime

INTRODUCTION

Neurological conditions such as Alzheimer's disease and stroke represent a substantial health burden to the world's ageing population. Cerebrovascular dysfunction is a key contributor to these conditions, affecting an individual's risk profile, age of onset, and severity of neurological disease. Recent data shows that early-life events, such as maternal health during pregnancy, birth weight and exposure to environmental toxins can 'prime' the vascular system for later changes. With age, blood vessels can become less flexible and more prone to damage. This can lead to reduced blood flow to the brain, which is associated with cognitive decline and an increased risk of stroke and other cerebrovascular diseases. These in turn increase the risk of vascular dementia and Alzheimer's disease.

OBJECTIVES

We aim to explore how early life factors influence cerebrovascular health, ageing and disease.

METHODS

We have reviewed recently published literature from epidemiological studies, clinical cases and basic research which explore mechanisms that contribute to cerebrovascular and blood-brain barrier dysfunction, with a particularly focus on those that assess contribution of early-life events or vascular priming to subsequent injury.

RESULTS

Perinatal events have been linked to acute cerebrovascular dysfunction and long-term structural reorganisation. Systemic disease throughout the lifetime that produce inflammatory or oxidative stress may further sensitise the cerebrovasculature to disease and contribute to neurodegeneration.

CONCLUSIONS

By identifying these early-life determinants and understanding their mechanisms, scientists aim to develop strategies for preventing or mitigating cerebrovascular ageing-related issues.

Mechanism Underlying the Regulation of Mucin Secretion in the Uterus during Pregnancy

The function of endometrial epithelial cells is to secrete various substances that are rich in growth factors and nutrients. These substances support both embryo implantation and its subsequent development into a fetus. A vast number of mucins are expressed in endometrial epithelial cells, and they play an important role in regulating the processes of embryo implantation, pregnancy, and parturition. Previous studies have shown that mucin forms a mucus layer covering endometrial epithelial cells, which helps resist damage from foreign bacteria and their toxins. Therefore, this article aims to investigate the location of mucins in the endometrium, the mechanism of mucin secretion by the endometrium, and the regulation of mucins in the uterine epithelium by reproductive hormones, as well as the role of mucins in the protection of the epithelium's structure. This research aims to provide a foundational understanding for future studies on the role and mechanism of endometrial mucins throughout the pregnancy cycle.

ATP-binding cassette (ABC) drug transporters in the developing blood-brain barrier: role in fetal brain protection

The blood-brain barrier (BBB) provides essential neuroprotection from environmental toxins and xenobiotics, through high expression of drug efflux transporters in endothelial cells of the cerebral capillaries. However, xenobiotic exposure, stress, and inflammatory stimuli have the potential to disrupt BBB permeability in fetal and post-natal life. Understanding the role and ability of the BBB in protecting the developing brain, particularly with respect to drug/toxin transport, is key to promoting long-term brain health. Drug transporters, particularly P-gp and BCRP are expressed in early gestation at the developing BBB and have a crucial role in developmental homeostasis and fetal brain protection. We have highlighted several factors that modulate drug transporters at the developing BBB, including synthetic glucocorticoid (sGC), cytokines, maternal infection, and growth factors. Some factors have the potential to increase expression and function of drug transporters and increase brain protection (e.g., sGC, transforming growth factor [TGF]-β). However, others inhibit drug transporters expression and function at the BBB, increasing brain exposure to xenobiotics (e.g., tumor necrosis factor [TNF], interleukin [IL]-6), negatively impacting brain development. This has implications for pregnant women and neonates, who represent a vulnerable population and may be exposed to drugs and environmental toxins, many of which are P-gp and BCRP substrates. Thus, alterations in regulated transport across the developing BBB may induce long-term changes in brain health and compromise pregnancy outcome. Furthermore, a large portion of neonatal adverse drug reactions are attributed to agents that target or access the nervous system, such as stimulants (e.g., caffeine), anesthetics (e.g., midazolam), analgesics (e.g., morphine) and antiretrovirals (e.g., Zidovudine); thus, understanding brain protection is key for the development of strategies to protect the fetal and neonatal brain.

Intrapartum fetal heart rate patterns and perinatal outcome in chorioamnionitis at or beyond 34 weeks of gestation

AIM

To investigate intrapartum fetal heart rate (FHR) patterns in women with chorioamnionitis at or beyond 34 weeks of gestation in relation to neonatal outcome and to compare clinical and subclinical chorioamnionitis.

METHODS

A retrospective questionnaire survey on deliveries during 2015 was conducted by the Perinatology Committee of the Japan Society of Obstetrics and Gynecology from 2016 to 2018. A total of 498 singleton births complicated by chorioamnionitis delivered at ≥34 weeks of gestation without major congenital malformations were included. The subjects were divided into clinical and subclinical chorioamnionitis groups based on Lencki's criteria. Poor perinatal outcome was defined as death or brain damage. We analyzed clinical features, FHR patterns in the last 2 h before delivery, gestational age, birthweight, Apgar score, umbilical arterial blood gas analysis, and infant's outcome.

RESULTS

Incidence of chorioamnionitis at ≥34 weeks of gestation was 0.59% (522/87827). Clinical and subclinical chorioamnionitis comprised 240 and 258 cases, respectively. Abnormal FHR patterns (late deceleration or decreased baseline variability) were significantly associated with poor perinatal outcome. Combined late deceleration and decreased variability showed low positive predictive value (12.8%) and high negative predictive value (99.5%), and was significantly associated with long-term poor outcome in clinical chorioamnionitis only (odds ratio: 29.4, p < 0.01). Poor perinatal outcome showed no significant difference between the clinical and subclinical chorioamnionitis groups.

CONCLUSIONS

Combined late deceleration and decreased variability could predict poor perinatal outcome in clinical chorioamnionitis. Poor perinatal outcome occurred in infants born to mothers with clinical and subclinical chorioamnionitis.