Oxygen, Volume 3, Issue 3 (September 2023) – 6 articles

Background: Emerging evidence suggests that the outcomes of hypoxia training may be influenced by various factors, contingent upon the chosen method, such as chamber, tent, or mask. This study aimed to examine how different training methods influence the effects of Repeated Sprints in Hypoxia (RSH) training. Methods: Sixteen well-trained cyclists were divided into two groups, experimental (tent; n = 8) and control (mask; n = 8), and carried out eight RSH sessions for four weeks. Training sessions consisted of three bouts of high-intensity sprints using a cycle ergometer. The indoor ambient conditions (CO₂, temperature, and humidity), performance variables (power and relative power output), arterial oxygen saturation, local muscle oxygen of vastus lateralis, heart rate, core temperature, and physiological variables (perception of effort) were measured in each training session. Results: The experimental group reported significantly higher CO₂ (p < 0.001 ES = 0.784), humidity levels (p < 0.001 ES = 0.750), thermal discomfort (p = 0.003 ES = 0.266), dehydration (p 0.025 ES = 0.097), heart rate (p = 0.017 ES = 0.113), and lower muscle oxygen amplification (p = 0.002 ES = 0.181) than the control group. Conclusion: According to the responses observed, interval training performed under hypoxic conditions inside a chamber induces a more severe physiological response. Full article

The pathogenesis of various gastrointestinal (GI) disorders, including gastritis, ulcers, inflammatory bowel disease (IBD) and cancer, can be linked to oxidative stress. It is known that reactive species carry out a crucial role in the genesis and progression of these pathologies; however, the contribution of ionic channels in their development is still under discussion. The function of ion channels in the gastrointestinal tract influences a variety of cellular processes. Acid-base balance, mucus layer, microbiota and mucosal blood flow are only some of the essential features for maintaining the mucosal integrity of the cellular barrier in the intestine, allowing for the preservation of proper permeability and ensuring tissue homeostasis. As the functional modulation of several ion channels is altered during oxidative stress conditions associated with gastrointestinal inflammation, this review focuses on contributing new insight into the roles of and the relationship between ion channels and oxidative stress in GI diseases. The association between ion channels and oxidative stress conditions could be used in diagnostics and the development of new pharmacological treatments for major gastrointestinal diseases. Full article

Molecular mechanisms based on photo-physical processes involving dietary carotenoids, their radicals, and the role of oxygen are discussed and used to suggest explanations of the poorly understood and often contradictory results related to mainly skin and vision. Differing and conflicting efficiencies of singlet oxygen reactions with carotenoids of biological importance are discussed in environments from ‘simple’ organic solvents to single He La cells. A range of free radical reactions with carotenoids, and the corresponding radicals of the carotenoids themselves, are compared and used to explain the switch from beneficial to deleterious processes involving dietary carotenoids and to unravel their differing functions; of particular interest is a possible role for vitamin C. Full article

Chronic kidney disease (CKD) affects 10% of the population. Fibrosis is the hallmark of CKD, which is marked by the deposit of extracellular matrix (ECM). This response is the final outcome of an unbalanced reaction to inflammation and wound healing and can be induced by a variety of insults, including hypoxia. Vascular damage results in an impaired tissue oxygen supply, inducing immune cell infiltration, tubule injury and the activation of ECM-secreting myofibroblasts. In turn, tubulointerstitial fibrosis development worsens oxygen diffusion. Hypoxia-inducible factor (HIF) is the primary transcriptional regulator of hypoxia-associated responses, such as oxidative stress and metabolic reprogramming, triggering a proinflammatory and profibrotic landscape. In this review, we discuss hypoxia-driven reprogramming in CKD as well as potential therapeutic approaches to target chronic hypoxia. Full article

Atmospheric oxygen is produced and consumed by life on Earth, and the ozone layer protects life on Earth from harmful solar UV radiation. The research on oxygen in the Earth system is of interest to many different geoscientific communities, from paleoclimatology to aeronomy. I provide a brief overview of the research activities and their motivations. In situ measurements and remote sensing of atmospheric oxygen are described. The global evolution, distribution, and trends of atmospheric oxygen are discussed. Full article

The aim of this study was to evaluate the efficiency of successive extraction (using solvents of increasing polarity, namely hexane, ethyl acetate, acetone, ethanol, and water) of polyphenols from Cistus creticus L. The results were compared with the ones obtained from a single-solvent extraction (ethanol, water, and 50% ethanol: water). According to the results, each solvent used for extraction had a significant effect on the yield of extracted polyphenols and the antioxidant activity of the extracts. The highest extraction yield for successive extraction was achieved with ethanol (95.33 mg GAE/g), whereas a comparable amount could also be extracted with 50% ethanol: water mixture single-solvent extraction (96.51 mg GAE/g). The ethanolic and aqueous extracts had the highest antioxidant activity as indicated by their lowest IC₅₀ values in the DPPH assay, specifically 350.99 μg/mL for ethanolic extract of successive extraction and 341.18 μg/mL for 50% ethanol: water mixture of single-solvent extraction, followed by the extract produced using acetone. However, the acetone extract contained more flavonoids than the other two extracts up to 28.03 mg QE/g. The results obtained were in line with those for the single-solvent extraction. It is concluded that using a range of solvents in succession is a more efficient way of extracting higher amounts of antioxidant compounds with varying antioxidant activity. Full article