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We investigated whether central or peripheral limitations to oxygen uptake elicit different respiratory sensations and whether dyspnea on exertion (DOE) provokes unpleasantness and negative emotions in patients with heart failure with preserved ejection fraction (HFpEF). 48 patients were categorized based on their cardiac output (Q̇c)/oxygen uptake (V̇O 2 ) slope and stroke volume (SV) reserve during an incremental cycling test. 15 were classified as centrally limited and 33 were classified as peripherally limited. Ratings of perceived breathlessness (RPB) and unpleasantness (RPU) were assessed (Borg 0-10 scale) during a 20 W cycling test. 15 respiratory sensations statements (1-10 scale) and 5 negative emotions statements (1-10) were subsequently rated. RPB (Central: 3.5±2.0 vs. Peripheral: 3.4±2.0, p=0.86), respiratory sensations, or negative emotions were not different between groups (p>0.05). RPB correlated (p<0.05) with RPU (r=0.925), "anxious" (r=0.610), and "afraid" (r=0.383). While DOE provokes elevated levels of negative emotions, DOE and respiratory sensations seem more related to a common mechanism rather than central and/or peripheral limitations in HFpEF., Competing Interests: Declaration of Competing Interest No conflicts of interest, financial or otherwise, are declared by the authors., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objectives: Psychological stress has been linked to common cold symptoms. Nitric oxide (NO) is part of the first line of epithelial defense against pathogens, and beetroot juice is a source of dietary nitrate that increases NO availability. We therefore tested whether beetroot juice protects against cold symptoms in a period of sustained acute stress., Design: Seventy-six students, 16 of these with asthma, were randomly assigned to seven daily doses of beetroot juice or no supplementation control during their final exams., Methods: Participants completed stress ratings, a cold symptom questionnaire, and exhaled NO measurements at a low-stress period and two periods during their final exams, with one questionnaire follow-up assessment seven days after finals., Results: Beetroot juice was associated with reduced symptoms of cold and sickness during and following finals. Those with asthma showed the greatest benefits. Higher exhaled NO was concurrently and prospectively associated with reduced symptomatology., Conclusion: Beetroot juice during periods of psychological stress protects against cold symptoms. Preliminary evidence suggests particular benefits in asthma, which could translate into reduced asthma exacerbations due to respiratory infections. Clinical Trial ID: NCT03159273., (Copyright © 2019. Published by Elsevier Inc.)

Background: Hydrogen sulfide (H 2 S) is the third gasotransmitter recently discovered after nitric oxide (NO) and carbon monoxide. Both NO and H 2 S are involved in multiple physiological functions. Whereas NO has been shown to vary with psychological stress, the influence of stress on H 2 S and the relationship between H 2 S and NO are unknown. We therefore examined levels of salivary H 2 S and NO in response to a stressful final academic exam period., Methods: Measurements of stress, negative affect, and fraction of exhaled NO (FE NO ), were obtained from students (N=16) and saliva was collected at three time points: low-stress period in the semester, early exam period, and late exam period. Saliva was immediately analyzed for H 2 S with the fluorescent probe Sulfidefluor-4., Results: H 2 S increased significantly during the early exam period and FE NO decreased gradually towards the late exam period. H 2 S, FE NO , negative affect, and stress ratings were positively associated with each other: as stress level and negative affect increased, values of H 2 S increased; in addition, as FE NO levels decreased, H 2 S also decreased. Asthma status did not modify these associations., Conclusion: Sustained academic stress increases H 2 S and these changes are correlated with NO and the experience of stress and negative affect. These findings motivate research with larger samples to further explore the interaction and function of H 2 S and FE NO during psychological stress., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Both individuals with asthma and depression show signs of a dysregulated hypothalamus-pituitary-adrenal axis. However, little is known about the cortisol response to stress in the context of co-occurring asthma and depressive mood. Thirty-nine individuals with asthma and 41 healthy controls underwent a combined speech and mental arithmetic stressor. During the course of the laboratory session, salivary cortisol was collected 5 times, with 1 sample at 0min before the stressor and 4 samples at 0, 15, 30 and 45min after the stressor. Depressive mood in the past week was assessed with the Hospital Anxiety and Depression Scale at the beginning of the session. Depressive symptoms moderated cortisol response to the acute stressor, but only among asthmatic patients. Higher depressive mood was associated with a significant increase in cortisol, whereas low depressive mood was associated with no cortisol response. In healthy participants, depressive mood had no substantial effect on cortisol response to the stressor. These findings suggest that depressive mood and chronic inflammatory diseases such as asthma can interact to augment cortisol response to stress., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Exposure to feared stimuli in blood-injection-injury (BII)-phobia is thought to elicit a diphasic response pattern, with an initial fight-flight-like cardiovascular activation followed by a marked deactivation and possible fainting (vasovagal syncope). However, studies have remained equivocal on the importance of such patterns. We therefore sought to determine the prevalence and clinical relevance of diphasic responses using criteria that require a true diphasic response to exceed cardiovascular activation of an emotional episode of a negative valence and to exceed deactivation of an emotionally neutral episode. Sixty BII-phobia participants and 20 healthy controls were exposed to surgery, anger and neutral films while measuring heart rate, blood pressure, respiratory pattern, and end-tidal partial pressure of carbon dioxide (as indicator of hyperventilation). Diphasic response patterns were observed in up to 20% of BII-phobia participants and 26.6% of healthy controls for individual cardiovascular parameters. BII-phobia participants with diphasic patterns across multiple parameters showed more fear of injections and blood draws, reported the strongest physical symptoms during the surgery film, and showed the strongest tendency to hyperventilate. Thus, although only a minority of individuals with BII phobia shows diphasic responses, their occurrence indicates significant distress. Respiratory training may add to the treatment of BII phobia patients that show diphasic response patterns., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Previous research suggests that acute stress can increase the release of immune-relevant proteins in saliva. However, no attempts have been made to examine a wider range of salivary proteins in response to stress. In this study, we identified and quantified changes in the pattern of salivary protein release in a 45 min time period following the Trier Social Stress Test (TSST) in 12 asthmatic and 13 healthy participants. Proteins were separated using sodium dodecyl sulfate polyacrylamide gel electrophoresis. The relative protein amounts were quantified using the Image J software (NIH), and identified and characterized using mass spectroscopy. Negative affect was increased immediately after stress in both groups. The results showed that alpha amylase, cystatin S and light chain IgA were increased after the TSST and significant increases in glutathione S-transferase and prolactin inducible protein were also observed. Asthma patients showed responses similar to healthy controls, but had a tendency toward overall lower alpha amylase levels. Our findings suggest that a variety of proteins relevant to mucosal immunity are elevated following acute psychosocial stress, including glutathione S-transferase and prolactin inducible protein, which had not been characterized in this context before., (Copyright © 2011 Elsevier Inc. All rights reserved.)

This article describes results on using steered molecular dynamics (SMD) simulations and experimental single molecule force spectroscopy (SMFS) to investigate the relationship between hydrogen bonding and mechanical stability of a series of homodimeric β-sheet mimics. The dimers consisting of 4, 6, and 8 H-bonding sites were modeled in explicit chloroform solvent and the rupture force was studied using constant velocity SMD. The role of solvent structuring on the conformation of the dimers was analyzed and showed no significant contribution of chloroform molecules in the rupture event. The simulated stability of the dimers was validated by force data obtained with atomic force microscopy (AFM)-based SMFS in toluene. The computational model for the 8H dimer also offered insight into a possible mismatched dimer intermediate that may contribute to the lower than expected mechanical stability observed by single molecule AFM force studies. In addition, atomic level analysis of the rupture mechanism verified the dependence of mechanical strength on pulling trajectory due to the directional nature of chemical bonding under an applied force. The knowledge gained from this basic study will be used to guide further design of modular polymers having folded nanostructures through strategic programming of weak, non-covalent interactions into polymer backbones.

Hyperventilation has numerous theoretical and empirical links to anxiety and panic. Voluntary hyperventilation (VH) tests have been applied experimentally to understand psychological and physiological mechanisms that produce and maintain anxiety, and therapeutically in the treatment of anxiety disorders. From the theoretical perspective of hyperventilation theories of anxiety, VH is useful diagnostically to the clinician and educationally to the patient. From the theoretical perspective of cognitive-behavior therapy, VH is a way to expose patients with panic disorder to sensations associated with panic and to activate catastrophic cognitions that need restructuring. Here we review panic disorder treatment studies using breathing training that have included VH. We differentiate the roles of VH in diagnosis, education about symptoms, training of breathing strategies, interoceptive exposure, and outcome measurement--discussing methodological issues specific to these roles and VH test reliability and validity. We propose how VH procedures might be standardized in future studies.