Oxygen, Volume 2, Issue 1 (March 2022) – 4 articles

Although there has been some controversy surrounding exactly when oxygen was first discovered, it is likely that that accolade should go to Carl Wilhelm Scheele, who isolated oxygen in 1772, or even a year earlier. Others since then have been given the credit for the instrumental work leading to the discovery including Joseph Priestley in 1774 and Antoine-Laurent Lavoisier. Oxygen, a paramagnetic, diradical gaseous (at room temperature) molecule, is instrumental to life as we know it. It is also crucial to some medical therapies, used in multiple industries and has even been found on other planets. The importance of oxygen cannot be overplayed. Now, 250 years since oxygen was discovered, it is timely to revisit some of the history, the controversies and look at how oxygen has evolved during that time. Here, a few of the highlights in oxygen research are discussed. Full article

Mammalian cell culture is widely used for discovery and development. Recently, increasing attention has been paid to the importance of maintaining physiologically-relevant conditions in cell culture. Although oxygen level is a particularly important consideration, it is rarely regulated by experimentalists. The atmospheric O₂ levels commonly used in cell culture are significantly higher than those experienced by most mammalian cells in vivo, leaving cells susceptible to oxidative damage, senescence, transformation, and otherwise aberrant physiology. A barrier to incorporating O₂ regulation into most cell culture workflows has been the expense of investing in new equipment, as the vast majority of laboratory CO₂ incubators do not regulate O₂. Here, we describe an inexpensive (<CAD 1000), portable and user-friendly O₂/CO₂ incubator that can establish and maintain physiological O₂, CO₂, and temperature values within their physiological ranges. We used an Arduino-based approach to add O₂ and CO₂ control to a temperature-regulating egg incubator. Our incubator was tested against a commercial laboratory O₂/CO₂ incubator. Using Presens OxoDish technology, we demonstrate that at a setpoint value of 5% gas-phase incubator O₂, media O₂ averaged 5.03 (SD = 0.03) with a range of 4.98–5.09%. MCF7, LNCaP and C2C12 cell lines cultured in the incubator displayed normal morphology, proliferation, and viability. Culture for up to one week produced no contamination. Thus, our incubator provides an inexpensive means of maintaining physioxia in routine mammalian cell culture. Full article

Uterine transplantation may be a solution for infertility of uterine origin. Nevertheless, only three pregnancies with a live birth have so far been possible involving a uterine transplant from a brain-dead donor. Particularly, the impact of ischemia needs a better understanding. Analysis of mitochondrial respiration and production of reactive oxygen species (ROS) in muscle are of interest since they are pertinent markers of the harmful effects of ischemia. We therefore studied both uterine fundus and horn muscle mitochondrial use of oxygen and ROS production in eight women needing hysterectomy. High resolution respirometry and electron paramagnetic resonance allowed the determination of, respectively, myometrium oxidative capacity, hydrogen peroxide, mitochondrial free radical leak and superoxide anion production early (2 and 7 h) and late (24 h) following surgery. Mitochondrial oxygen consumption of the uterine fundus and horn tended to decrease with time but this was not statistically significant. Concerning ROS production, globally, we observed no significant change for H₂O₂, superoxide anion and free radical leak. In conclusion, a long period of cold ischemia did not impair myometrium mitochondrial respiration, only generating a transient H₂O₂ increase in uterine fundus. These data support that cold ischemia, even when prolonged, does not significantly alter uterine muscle oxidative capacity. Full article

Background: Infertility, defined as the failure to conceive after one year of regular, unprotected intercourse, affects 50–80 million people worldwide. A male factor is involved in approximately 20–30% of cases. In the etiology of male infertility, the association between poor semen quality and oxidative stress (OS) is well known. High levels of reactive oxygen species (ROS) allow the oxidation of DNA, proteins, and lipids of sperm cells, modifying their vitality, motility, and morphology. Methods: To evaluate the effects of antioxidants on sperm in infertile men, we queried the MEDLINE database (via the PubMed interface) for published studies in the last 10 years (2011–2021). The following keywords were used: “infertility” and -“inositol”, -“alpha-lipoic acid”, -“zinc”, -“folate”, -“coenzyme Q10”, -“selenium”, and -“vitamin”. Results: Inositol regulates OS levels in sperm cells thanks to its role in mitochondrial reactions and is involved in several processes favoring sperm–oocyte interactions. Alpha-lipoic acid (ALA) reduces ROS damage and improves semen parameters in terms of spermatozoa’s motility, morphology, and count. Poor zinc nutrition may be related to low quality of sperm. Supplementation of folate plus zinc has a positive effect on the sperm concentration and morphology. Supplementation with CoQ10 increases sperm concentration, total and progressive motility. Selenium (Se) supplementation improves the overall semen quality and is related to a higher ejaculated volume. Among vitamins, only vitamin B12 shows a positive effect on semen quality; it increases sperm count and motility and reduces sperm DNA damage. Conclusions: In men showing low-quality semen, diet supplementation with antioxidants may improve the sperm quality by alleviating OS-induced sperm damage and enhancing hormone synthesis and spermatozoa concentration, motility, and morphology. Future clinical trials should be focused on the possible association of several antioxidants to take advantage of combined mechanisms of action. Full article