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In a preregistered, cross-sectional study, we investigated whether olfactory loss is a reliable predictor of COVID-19 using a crowdsourced questionnaire in 23 languages to assess symptoms in individuals self-reporting recent respiratory illness. We quantified changes in chemosensory abilities during the course of the respiratory illness using 0-100 visual analog scales (VAS) for participants reporting a positive (C19+; n = 4148) or negative (C19-; n = 546) COVID-19 laboratory test outcome. Logistic regression models identified univariate and multivariate predictors of COVID-19 status and post-COVID-19 olfactory recovery. Both C19+ and C19- groups exhibited smell loss, but it was significantly larger in C19+ participants (mean ± SD, C19+: -82.5 ± 27.2 points; C19-: -59.8 ± 37.7). Smell loss during illness was the best predictor of COVID-19 in both univariate and multivariate models (ROC AUC = 0.72). Additional variables provide negligible model improvement. VAS ratings of smell loss were more predictive than binary chemosensory yes/no-questions or other cardinal symptoms (e.g., fever). Olfactory recovery within 40 days of respiratory symptom onset was reported for ~50% of participants and was best predicted by time since respiratory symptom onset. We find that quantified smell loss is the best predictor of COVID-19 amongst those with symptoms of respiratory illness. To aid clinicians and contact tracers in identifying individuals with a high likelihood of having COVID-19, we propose a novel 0-10 scale to screen for recent olfactory loss, the ODoR-19. We find that numeric ratings ≤2 indicate high odds of symptomatic COVID-19 (4 < OR < 10). Once independently validated, this tool could be deployed when viral lab tests are impractical or unavailable.

Across sensory systems, several stimulus collative characteristics, including intensity, novelty, complexity and perceived dangerousness, are known to elicit high levels of physiological and psychological arousal. It has become apparent that food rejections by both children and adults are frequently linked to such arousal-inducing characteristics. This paper examines how arousal and arousability are important elements in responding to stimuli generally, but specifically to foods, ultimately influencing food preferences and choices. It is clear that responses to sensory properties are subject not just to variations in perceptual sensitivity due to genetics or experience—as in the case of widely rejected qualities such as bitterness or pungency—but also to the arousal potential of those stimuli. Moreover, this is linked to various enduring aspects of personality, suggesting that the impact of arousal on food choices is merely one aspect of a more general sensory sensitivity. The impact of diet on various health outcomes underlines the importance of understanding the relationship of arousal to food choices. This article is part of the theme issue 'Sensing and feeling: an integrative approach to sensory processing and emotional experience'. [ABSTRACT FROM AUTHOR]

Prediabetes is a risk state that defines a high chance of developing diabetes and cardiovascular disease. Oxidative stress mediated by hyperglycemia‐induced production of reactive species could play a crucial role in this context. In the present study, we investigated whether the anion exchange capability mediated by AE1 (SLC4A1), which is sensitive to oxidative stress, was altered in human red blood cells (RBCs) obtained from prediabetic volunteers. In addition, we assessed the precise composition of bioactive compounds and the potential benefits of finger lime juice extract (Citrus australasica, Faustrime cultivar) in counteracting oxidative stress‐related functional alterations. Human RBCs from normal and prediabetic volunteers were incubated with 50 µg/mL juice extract for 2 h at 25°C. Juice extract restored alterations of the anion exchange capability mediated by AE1 and prevented the structural rearrangements of AE1 and α/β‐spectrin in prediabetic RBCs. AE1 functional and structural alterations were not associated with an increase in lipid peroxidation or protein oxidation at the level of the plasma membrane. An increased production of intracellular ROS, which provoked the oxidation of hemoglobin to methemoglobin, both reverted by juice extract, was instead observed. Importantly, juice extract also induced a reduction in glycated hemoglobin levels in prediabetic RBCs. Finally, juice extract blunted the overactivation of the endogenous antioxidant enzymes catalase and superoxide dismutase and prevented glutathione depletion in prediabetic RBCs. These findings contribute to clarifying cellular and molecular mechanisms related to oxidative stress and glycation events that may influence RBC and systemic homeostasis in prediabetes, identify AE1 as a sensitive biomarker of RBC structural and function alterations in prediabetes and propose finger lime juice extract as a natural antioxidant for the treatment and/or prevention of the complications associated with the prediabetic condition. SIGNIFICANCE STATEMENT: The data obtained here reveal that structural and functional alterations related to the increase of oxidative stress and/or glycation events can still be reversible and the early application of bioactive molecules could counteract the majority of derangements in prediabetic RBCs. This study identifies finger lime as an antioxidant/anti‐glycation functional food and suggests that diet supplementation with finger lime might contribute to the prevention or attenuation of pathophysiological events linked to RBC dysfunction during the prediabetic condition. Additionally, our findings proved that measurement of anion exchange capability via AE1 remains a valid tool for monitoring the impact of oxidative stress/glycation on human RBC and systemic homeostasis. [ABSTRACT FROM AUTHOR]

Melatonin is a pleiotropic biofactor and an effective antioxidant and free radical scavenger and, as such, can be protective in oxidative stress‐related brain conditions including epilepsy and aging. To test the potential protective effect of melatonin on brain homeostasis and identify the corresponding molecular targets, we established a new model of oxidative stress‐related aging neuroglia represented by U‐87 MG cells exposed to D‐galactose (D‐Gal). This model was characterized by a substantial elevation of markers of oxidative stress, lipid peroxidation, and protein oxidation. The function of the inward rectifying K+ channel Kir2.1, which was identified as the main Kir channel endogenously expressed in these cells, was dramatically impaired. Kir2.1 was unlikely a direct target of oxidative stress, but the loss of function resulted from a reduction of protein abundance, with no alterations in transcript levels and trafficking to the cell surface. Importantly, melatonin reverted these changes. All findings, including the melatonin antioxidant effect, were reproduced in heterologous expression systems. We conclude that the glial Kir2.1 can be a target of oxidative stress and further suggest that inhibition of its function might alter the extracellular K+ buffering in the brain, therefore contributing to neuronal hyperexcitability and epileptogenesis during aging. Melatonin can play a protective role in this context. [ABSTRACT FROM AUTHOR]