The effect of plasma cortisol on hippocampal atrophy and clinical progression in mild cognitive impairment.

Introduction: Both elevated cortisol and hippocampal volume have been linked to an increased risk for the development of Alzheimer's disease (AD). This longitudinal study assessed the effects of plasma cortisol on hippocampal atrophy and clinical progression rates in patients with mild cognitive impairment (MCI). Methods: Patients with amnestic MCI (n = 304) were selected from the Alzheimer's Disease Neuroimaging Initiative (ADNI) based on availability of baseline plasma cortisol and hippocampal volume measures, assessed at baseline and during follow-ups. We investigated associations between plasma cortisol, hippocampal volume, and risk of clinical progression to AD over a study period of up to 100 months (mean follow-up time 36.8 months) using linear mixed models, Cox proportional hazards models, and Kaplan-Meier estimators. Results: Plasma cortisol predicted greater hippocampal atrophy, such that participants with higher cortisol showed faster decline in hippocampal volume over time (interaction: ß = -0.15, p = 0.004). Small hippocampal volume predicted a higher risk of clinical progression to AD (haard ratio [HR] = 2.15; confidence in terval [CI], 1.64-2.80; p < 0.001). A similar effect was not found for cortisol (HR = 1.206; CI, 0.82-1.37; p = 0.670) and there was no statistical evidence for an interaction between hippocampal volume and cortisol on clinical progression (HR = 0.81; CI, 0.57-0.17; p = 0.260). Discussion: Our findings suggest that higher cortisol predicts higher hippocampal atrophy, which in turn is a risk factor for progression to AD. Regulation of the hypothalamic-pituitary-adrenal axis through stress-reducing lifestyle interventions might be a protective factor against hippocampal degeneration at the prodromal stage of AD.

Correlative light and electron microscopy of intermediate stages of meiotic spindle assembly in the early Caenorhabditis elegans embryo.

This chapter is an update of the previously published book chapter "Correlative Light and Electron Microscopy of Early C. elegans Embryos in Mitosis" (Müller-Reichert, Srayko, Hyman, O'Toole, & McDonald, 2007). Here, we have adapted and improved the protocol for the isolated meiotic embryos, which was necessary to meet the specific challenges a researcher faces while investigating the development of very early Caenorhabditis elegans embryos ex-utero. Due to the incompleteness of the eggshell assembly, the meiotic embryo is very fragile and much more susceptible to changes in the environmental conditions than the mitotic ones. To avoid phototoxicity associated with wide-field UV illumination, we stage the meiotic embryos primarily using transmitted visible light. Throughout the staging and high-pressure freezing, we incubate samples in an isotonic embryo buffer. The ex-utero approach allows precise tracking of the developmental events in isolated meiotic embryos, thus facilitating the comparison of structural features between wild-type and mutant or RNAi-treated samples.