Effects of intrauterine exposure to synthetic glucocorticoids on fetal, newborn, and infant hypothalamic-pituitary-adrenal axis function in humans : a systematic review

BACKGROUND: Synthetic glucocorticoids are commonly used in reproductive medicine. Fetal organ systems are highly sensitive to changes in the intrauterine environment, including overexposure to glucocorticoids. Structural and functional alterations resulting from such changes may persist throughout life and have been associated with diverse diseases. One system that could be particularly sensitive to fetal glucocorticoid overexposure is the hypothalamic-pituitary-adrenal (hpa) axis. Many human studies have investigated this possibility, but a systematic review to identify consistent, emergent findings is lacking. METHODS: We systematically review 49 human studies, assessing the effects of intrauterine exposure to synthetic glucocorticoids on fetal, neonate, and infant hpa function. RESULTS: Study quality varied considerably, but the main findings held true after restricting the analyses to higher-quality studies: intrauterine exposure to synthetic glucocorticoids reduces offspring hpa activity under unstimulated conditions after pain but not pharmacological challenge. Although reduced unstimulated hpa function appears to recover within the first 2 wk postpartum, blunted hpa reactivity to pain is likely to persist throughout the first 4 months of life. There is some evidence that the magnitude of the effects is correlated with the total amount of glucocorticoids administered and varies with the time interval between glucocorticoid exposure and hpa assessment. CONCLUSIONS: This systematic review has allowed the demonstration of the way in which intrauterine exposure to various regimens of synthetic glucocorticoids affects various forms of hpa function. As such, it guides future studies in terms of which variables need to be focused on in order to further strengthen the understanding of such therapy, whilst continuing to profit from its clinical benefits

Formation of Colloidal Nanocellulose Glasses and Gels

Nanocellulose (NC) suspensions can form rigid volume-spanning arrested states (VASs) at very low volume fractions. The transition from a free-flowing dispersion to a VAS can be the result of either an increase in particle concentration or a reduction in interparticle repulsion. In this work, the concentration-induced transition has been studied with a special focus on the influence of the particle aspect ratio and surface charge density, and an attempt is made to classify these VASs. The results show that for these types of systems two general states can be identified: glasses and gels. These NC suspensions had threshold concentrations inversely proportional to the particle aspect ratio. This dependence indicates that the main reason for the transition is a mobility constraint that, together with the reversibility of the transition, classifies the VASs as colloidal glasses. If the interparticle repulsion is reduced, then the glasses can transform into gels. Thus, depending on the preparation route, either soft and reversible glasses or stiff and irreversible gels can be formed