Systems redox biology in health and disease

A Droplet Microfluidic Sensor for Point-of-Care Measurement of Plasma/Serum Total Free Thiol Concentrations

Total free thiols are an important marker of the whole-body redox state, which has been shown to be associated with clinical outcome in health and disease. Recent investigations have suggested that increased insight may be gained by monitoring alterations of redox state in response to exercise and hypoxia and to monitor redox trajectories in disease settings. However, conducting such studies is challenging due to the requirement for repeated venous blood sampling and intensive lab work. Droplet microfluidic sensors offer an alternative platform for developing a point-of-care testing approach using small sample volumes and automated systems to complement or ultimately replace laboratory testing. Here we developed a small, portable droplet microfluidic sensor that can measure total free thiol concentrations in 20 μL human plasma (or serum) samples, providing a reading in less than 10 min. This system features a novel method to enhance the mixing of reagent and analyte in droplets containing viscous biological fluids. The results in a range of real-world human plasma samples showed equivalence with current standard laboratory assays while reducing sample volume requirements 9-fold and fully automating the process. Micro hematocrit capillaries allowed testing of capillary blood samples collected by fingerprick lancing. The system was used to monitor total free thiols using fingerprick samples in healthy volunteers and revealed significant changes in total free thiols in response to food intake and exercise. This device has the potential to improve our ability to conduct physiological studies of total free thiol level changes and improve our understanding of redox physiology, which may ultimately be applied in redox medicine to improve patient care.

Review of cancer cell volatile organic compounds: their metabolism and evolution

Cancer is ranked as the top cause of premature mortality. Volatile organic compounds (VOCs) are produced from catalytic peroxidation by reactive oxygen species (ROS) and have become a highly attractive non-invasive cancer screening approach. For future clinical applications, however, the correlation between cancer hallmarks and cancer-specific VOCs requires further study. This review discusses and compares cellular metabolism, signal transduction as well as mitochondrial metabolite translocation in view of cancer evolution and the basic biology of VOCs production. Certain cancerous characteristics as well as the origin of the ROS removal system date back to procaryotes and early eukaryotes and share commonalities with non-cancerous proliferative cells. This calls for future studies on metabolic cross talks and regulation of the VOCs production pathway.

Fundamentals of redox regulation in biology

Oxidation-reduction (redox) reactions are central to the existence of life. Reactive species of oxygen, nitrogen and sulfur mediate redox control of a wide range of essential cellular processes. Yet, excessive levels of oxidants are associated with ageing and many diseases, including cardiological and neurodegenerative diseases, and cancer. Hence, maintaining the fine-tuned steady-state balance of reactive species production and removal is essential. Here, we discuss new insights into the dynamic maintenance of redox homeostasis (that is, redox homeodynamics) and the principles underlying biological redox organization, termed the 'redox code'. We survey how redox changes result in stress responses by hormesis mechanisms, and how the lifelong cumulative exposure to environmental agents, termed the 'exposome', is communicated to cells through redox signals. Better understanding of the molecular and cellular basis of redox biology will guide novel redox medicine approaches aimed at preventing and treating diseases associated with disturbed redox regulation.

Dysregulation of mood, energy, and social rhythms syndrome (DYMERS): A working hypothesis

A syndrome centered on the dysregulation of behavioral rhythms (DBR) is discussed. Recent pandemic brought to observe: (1) Having a DBR affecting sleep patterns, eating habits, and social interactions, before the lockdown period, was a determinant for depressive episodes during the lockdown; (2) In tighter lockdowns, DBR triggered depressive episodes in bipolar patients; (3) DBR in healthcare workers under pressure was a determinant of burnout; (4) DBR influenced the course of chronic diseases by altering immune responses. In addition, it was found that scoring positive on the Mood Disorder Questionnaire (MDQ) was closely associated with the dysregulation of sleep rhythms. MDQ is a screening tool for bipolar disorder (BD), criticized for detecting too many false positives. Studies showed that positivity to the MDQ implied a severe impairment of quality of life even in people without psychiatric diagnoses. According to this evidence, three different hyperactivation levels could be proposed (from normality to pathology): firstly, an adaptive increase in energy (e.g. athletes performing well); secondly, a DBR determined from the continuous stimulation of stress hormones, with possible positive scores on the MDQ without a diagnosis of bipolar disorder, like in burnout syndromes and, thirdly, hyperactivity during manic episodes. The Dysregulation of Mood, Energy, and Social Rhythms Syndrome (DYMERS), the second level of the scale, is proposed as a working hypothesis. DYMERS is also seen as a vulnerable condition that may evolve in other disorders (including BD) according to the individual susceptibility (including genetic predisposition) and the specific nature/level of the stressor.

Salivary Redox Homeostasis in Human Health and Disease

Homeostasis is a self-regulatory dynamic process that maintains a stable internal environment in the human body. These regulations are essential for the optimal functioning of enzymes necessary for human health. Homeostasis elucidates disrupted mechanisms leading to the development of various pathological conditions caused by oxidative stress. In our work, we discuss redox homeostasis and salivary antioxidant activity during healthy periods and in periods of disease: dental carries, oral cavity cancer, periodontal diseases, cardiovascular diseases, diabetes mellitus, systemic sclerosis, and pancreatitis. The composition of saliva reflects dynamic changes in the organism, which makes it an excellent tool for determining clinically valuable biomarkers. The oral cavity and saliva may form the first line of defense against oxidative stress. Analysis of salivary antioxidants may be helpful as a diagnostic, prognostic, and therapeutic marker of not only oral, but also systemic health.