One of the most important tools used to evaluate kidney function in the context of chronic kidney disease or other renal function related pathologies is the exploration of glomerular filtration rate (GFR). Iohexol is up to this moment a good candidate molecule for the GFR assessment since it exhibits minimum protein binding rates and minimum extra-renal clearance, being neither secreted nor reabsorbed at the tubular level. This study proposes and evaluates a new LC-MS/MS method for the iohexol determination from capillary blood, prelevated using volumetric absorbative microsampling (VAMS) systems. As an alternative to VAMS, a brand new HemaPEN ® device for micro-prelevation was also tested. A new high throughput sample preparation protocol adapted for iohexol quantification from whole blood VAMS samples was developed. The medium term stability study of iohexol in dried whole blood VAMS samples that was conducted showed a good stability of this molecule for up to 12 days. By collecting only 10 μL of blood, iohexol can be analyzed from dried whole blood VAMS samples for concentration ranges between 1 and 250 μg/mL. Due to the analyte stability in VAMS for up to 12 days, this approach might be successfully applied for GFR assessment for clinical cases allowing minimum invasiveness and even delayed analysis.

We aimed at assessing whether a head-mounted light therapy device, enriched in blue wavelengths, suppresses melatonin secretion and improves vigilant attention in the late evening hours. We also assessed whether using such light device is associated with discomfort and physiological stress. Seventeen healthy young participants (eight females) participated in a counterbalanced within-subject design during which they were exposed for 2 hr before habitual sleep time to a blue-enriched light (1500 lx) or to a lower intensity red-light (150 lx) control condition, using a new-generation light emitting diode (LED) head-mounted device. Compared to the red light control condition, blue-enriched light significantly reduced melatonin secretion and reaction times during a psychomotor vigilance task while no significant differences were detected in discomfort and cortisol levels. These results suggest that, compared to a control condition, blue-enriched light, delivered by a new-generation head-mounted device, elicits typical non-visual responses to light without detectable discomfort and physiological stress. They suggest that such devices might constitute an effective alternative to standard light boxes.

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Growing epidemiological evidence points toward an association between fragmented 24‐h rest–activity cycles and cognition in the aged. Alterations in the circadian timing system might at least partially account for these observations. Here, we tested whether daytime rest (DTR) is associated with changes in concomitant 24‐h rest probability profiles, circadian timing and neurobehavioural outcomes in healthy older adults. Sixty‐three individuals (59–82 years) underwent field actigraphy monitoring, in‐lab dim light melatonin onset assessment and an extensive cognitive test battery. Actimetry recordings were used to measure DTR frequency, duration and timing and to extract 24‐h rest probability profiles. As expected, increasing DTR frequency was associated not only with higher rest probabilities during the day, but also with lower rest probabilities during the night, suggesting more fragmented night‐time rest. Higher DTR frequency was also associated with lower episodic memory performance. Moreover, later DTR timing went along with an advanced circadian phase as well as with an altered phase angle of entrainment between the rest–activity cycle and circadian phase. Our results suggest that different DTR characteristics, as reflective indices of wake fragmentation, are not only underlined by functional consequences on cognition, but also by circadian alteration in the aged.