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Author(s): Juanita Kay Miller Berry [sup.1] , Peter D. Drummond [sup.1] Author Affiliations: (1) School of Psychology and Exercise Science, Murdoch University, 0000 0004 0436 6763, grid.1025.6, , 6150, Perth, [...], Psychological stress triggers headaches, but how this happens is unclear. To explore this, 38 migraine sufferers, 28 with tension-type headache (T-TH) and 20 controls rated nausea, negative affect, task-expectancies and headache at 5-min intervals during an aversive 20-min mental arithmetic task with a fixed failure rate. Blood pressure and pulse rate were measured every 3 min and salivary cortisol was sampled before and after the task. Multiple regression analysis indicated that irritation, anxiety and the absence of sluggishness (i.e., alertness) independently predicted increases in headache intensity during the task (p < .001), but increases in headache were unrelated to changes in cardiovascular activity or cortisol. Changes that preceded headache onset were explored in repeated measures ANOVAs, comparing those who developed headache with those who did not. In general, nausea, negative affect and self-efficacy expectancies were higher in participants who went on to develop headache than in those who remained headache-free (p < .05 to p < .001). Together, these findings suggest that headache developed when participants overextended themselves during a stressful task, adopting an information processing style which impeded emotional adjustment to changing situational demands. Learning to modify perceptions of threat, and adopting a more flexible, less outcome-dependent processing style, might help to prevent headache from spiralling upward.

Introduction Antioxidants are reducing chemicals that are able to inhibit or prevent oxidation processes and/or to interrupt radical chain reactions. Such compounds may be produced within the human body or [...], Oxidative stress is considered to be critically involved in the normal aging process but also in the development and progression of various human pathologies like cardiovascular and neurodegenerative diseases, as well as of infections and malignant tumors. These pathological conditions involve an overwhelming production of reactive oxygen species (ROS), which are released as part of an anti-proliferative strategy during pro-inflammatory immune responses. Moreover, ROS themselves are autocrine forward regulators of the immune response. Most of the beneficial effects of antioxidants are considered to derive from their influence on the immune system. Due to their antioxidant and/or radical scavenging nature, phytochemicals, botanicals and herbal preparations can be of great importance to prevent oxidation processes and to counteract the activation of redox-regulated signaling pathways. Antioxidants can antagonize the activation of T-cells and macrophages during the immune response and this anti-inflammatory activity could be of utmost importance for the treatment of above-mentioned disorders and for the development of immunotolerance. Herein, we provide an overview of in vitro assays for the measurement of antioxidant and antiinflammatory activities of plant-derived substances and extracts, by discussing possibilities and limitations of these methods. To determine the capacity of antioxidants, the oxygen radical absorbance capacity (ORAC) assay and the cell-based antioxidant activity (CAA) assay are widely applied. To examine the influence of compounds on the human immune response more closely, the model of mitogen stimulated human peripheral blood mononuclear (PBMC) cells can be applied, and the production of the inflammatory marker neopterin as well as the breakdown of the amino acid tryptophan in culture supernatants can be used as readout to indicate an immunomodulatory potential of the tested compound. These two biomarkers of immune system activation are robust and correlate with the course of cardiovascular, neurodegenerative and malignant tumor diseases, but also with the normal aging process, and they are strongly predictive. Thus, while the simpler ORAC and CAA assays provide insight into one peculiar chemical aspect, namely the neutralization of peroxyl radicals, the more complex PBMC assay is closer to the in vivo conditions as the assay comprehensively enlights several properties of immunomodulatory test compounds. Keywords: Cell-based antioxidant activity (CAA) Immunomodulation Inflammation In vitro test systems Oxidative stress Oxygen radical absorbance capacity (ORAC) assay Peripheral blood mononuclear cells Reactive oxygen species