Oxygen

With humans living longer and the median age of the population increasing, there is an ever-increasing demand for better biomedical implants. Titanium implants have a long history of successful use, but their naturally forming amorphous oxide surfaces are not ideal to promote bone growth. Therefore, titanium surfaces are often modified to improve bioactivity through electrochemical processes such as anodization which can crystallize the oxide into more bioactive titanium oxide phases, form hierarchical micro- and nano-scale roughness profiles, and incorporate beneficial bone chemistry into the oxide layer to improve interactions with bone cells. We have recently developed three innovative anodization electrolytes based on combinations of citrus fruit juices and commercially available calcium compounds. Anodization in these electrolytes produced citrus-based oxides exhibiting surface Ca/P ratios within the range of human bone, unique cauliflower-like hierarchical micro- and nano-scale surface roughness profiles, and the formation of titanate compounds which have been shown to be precursors for subsequent apatite formation. Thus, our titanate-containing citrus-based oxides show much promise for improving future osseointegration. Full article

The biology literature addresses two puzzles: (i) the increase in specific metabolic rate of organs (SOrMR, W/kg of organ) with a decrease in body mass (M_B) of biological species (BS), and (ii) how the organs recognize they are in a smaller or larger body and adjust metabolic rates of the body (${\dot{q}}_B$) accordingly. These puzzles were answered in the author’s earlier work by linking the field of oxygen-deficient combustion (ODC) of fuel particle clouds (FC) in engineering to the field of oxygen-deficient metabolism (ODM) of cell clouds (CC) in biology. The current work extends the ODM hypothesis to predict the whole-body metabolic rates of 114 BS and demonstrates Kleiber’s power law {${\dot{q}}_B = a {M_B}^b$}. The methodology is based on the postulate of Lindstedt and Schaeffer that “150 ton blue whale. and the 2 g Etruscan shrew.. share the same.. biochemical pathways” and involve the following steps: (i) extension of the effectiveness factor relation, expressed in terms of the dimensionless group number G (=Thiele Modulus²), from engineering to the organs of BS, (ii) modification of G as G_OD for the biology literature as a measure of oxygen deficiency (OD), (iii) collection of data on organ and body masses of 116 species and prediction of SOrMR_k of organ k of 114 BS (from 0.0076 kg Shrew to 6650 kg elephant) using only the SOrMR_k and organ masses of two reference species (Shrew, 0.0076 kg: RS-1; Rat Wistar, 0.390 kg: RS-2), (iv) estimation of ${\dot{q}}_B$ for 114 species versus M_B and demonstration of Kleiber’s law with a = 2.962, b = 0.747, and (v) extension of ODM to predict the allometric law for maximal metabolic rate (under exercise, {${\dot{q}}_{B,MMR} = a_{MMR} {M_B}^{b_{MMR}}$}) and validate the approach for MMR by comparing b_MMR with the literature data. A method of detecting hypoxic condition of an organ as a precursor to cancer is suggested for use by medical personnel Full article

In a previous Arabidopsis investigation, three ovule-specific cell-wall peroxidases decreased seed abortion rates. These peroxidases were expressed in soybean plants. Because cell wall peroxidases alter extensibility, possible effects on seed size and plant yield were evaluated. Since the effects of these peroxidases in Arabidopsis were dependent on environmental stress, soybean plants were grown in controlled environment greenhouse rooms under four temperature treatments; the daily temperature averages were 26, 30, 34, and 38 °C. In this experiment in vivo oxygen levels during seed growth were 25-fold below ambient, which could affect peroxidase activities. Consequently, soybeans were grown at atmospheric (21%) and elevated (32%) O₂ to evaluate peroxidase activities at higher O₂. Chambers were maintained at 700 ppm CO₂ in an attempt to minimize photorespiration in elevated O_2. Individual seed weight decreased with increasing temperature to zero at 38 °C. In elevated O₂ rooms, the oxygen concentration in developing seeds increased, but, due to leaf photorespiration, plant biomass and seed yield decreased. Seed size and shelling percentage declined equally with temperature at both O₂ concentrations. Expression of all three cell-wall peroxidases reduced seed abortion; however, that did not increase yields at ambient or elevated O₂. While O₂ concentration is less than 1% in developing seeds, increased O₂ levels in seeds were not beneficial for soybean reproduction. Full article

Because soybean is sensitive to salt stress, it is necessary to improve their stress tolerance. Titanium-oxide nanoparticles (TiO₂ NPs) enhanced the growth of soybean under salt stress. To elucidate the promotive effects of TiO₂ NPs on soybean growth under salt stress, a gel-free/label-free proteomic analysis was carried out. The principal component analysis of proteins showed that TiO₂ NPs affected proteins in roots grown under salt stress. The differentially changed proteins were associated with protein metabolism and transport in the biological process, the nucleus in the cellular component, and nucleic acid binding activity in the molecular function. Proteins identified with proteomics were verified using immunoblot analysis. The abundance of V-ATPase decreased in soybean under salt stress and increased with additional TiO₂ NPs under stress, whereas xyloglucan endotransglucosylase/hydrolase did not change with any treatment. The abundance of peroxiredoxin increased under salt stress but decreased with additional TiO₂ NPs under stress. These results suggest that TiO₂ NPs confer salt tolerance in soybean plants at the early growth stage by regulating vacuole transport and reactive oxygen scavenging systems. Full article

Pharyngocutaneous fistulas (PCF) are a common postoperative complication following head and neck surgery, particularly after total laryngectomy. These types of fistulas represent a challenge for both patients and clinicians due to their persistence and resistance to conventional healing methods. Hyperbaric Oxygen Therapy (HBOT) has been proposed as an adjunctive treatment to enhance healing and closure of PCF. While many studies report positive outcomes, the results are not universally consistent. This comprehensive review aimed to examine the clinical evidence supporting the efficacy of HBOT in the management of pharyngocutaneous fistulas, focusing on fistula closure rates, infection control, and overall healing improvement. All publications without the restriction of time and published in the English language were included. Searches were performed in the PubMed, MEDLINE, Scopus, and Embase databases. Ten articles were included in this review. The evaluation of our clinical experience with this method of treating PCF showed results comparable to those found in the literature and analyzed among the studies reviewed. Several studies indicate that HBOT promotes fistula closure, reduces healing time, and enhances the local immune response, but further investigation is required to optimize protocols and patients’ selections. Full article

Photodynamic therapy (PDT) is an effective method of preventing the progression of cancer. The PDT method guarantees localized generation of singlet oxygen (¹O₂), which is toxic to the cells. Therefore, this treatment, also called light-activated chemotherapy, is particularly useful for tumors whose location is difficult to access but needs to be known. Therefore, PDT may be an alternative method to the surgical removal of the tumor by replacing the scalpel tool with three factors, i.e., light, a photosensitizer and oxygen, to generate singlet oxygen in the cell. Herein, primary brain tumors that probably originate from neuroglial stem or progenitor cells are discussed. In this review, we have included current information on the use of PDT in the treatment of gliomas in the context of genetics. We have mainly focused on the study of the use of PDT in patients with genetic syndromes that are associated with an increased risk of glioma. The review also uses information on genetic syndromes that are important for the diagnosis and treatment of patients with glioma. We discuss the association between brain tumors and a few genetic abnormalities. In this review, we highlight the molecular mechanism of human cell response to PDT based on the literature data. In treated samples, significant changes in gene expression were noted after PDT. Full article

Previous studies indicate that individuals at high altitudes have a lower pain threshold than those living at sea level. This study evaluates the differences in pain perception among young people living at an altitude of 3800 m and after acute exposure to a severe hypoxic environment at more than 5100 m. Fourteen people (BMI of 22.6 ± 1.2 and age of 23.3 ± 1.9 years) residing in the city of Puno (3825 m) participated in an ascent to the Populated Center of La Rinconada (>5100 m). The unilateral ischemia pain provocation test was used, applying pressure with a manual sphygmomanometer to generate transient ischemia in the arm while the patient opens and closes their hand. Onset, peak, and resolution times of pain, heart rate, and oxygen saturation were recorded. At their residence altitude of 3828 m, the mean hemoglobin was 16.16 ± 2.29, while at 5100 m, mean hemoglobin increased to 17.57 ± 1.74. The average time to pain onset in the right arm was 30.43 s ± 14.15 at 3828 m, whereas at 5100 m above sea level, the pain perception was at 31.00 s ± 19.01. At 3828 m, the average time until pain sensation in the left arm was 19.93 s ± 9.44 and increased to 23.07 s ± 10.83 at 5100 m. During exposure to a severe hypoxic environment, the pain perception threshold was similar between 3828 m and 5100 m above sea level. Full article

Nanoparticles are a mainstay of heterogeneous catalysis. This is in part due to their mesoscopic structure; they can be grown to have large available surface areas which can be both regenerative and durable in reaction. Their utility is possible by the alloys used in their production—however, analysis of their operation is generally at the DFT or molecular dynamics level. This review will present an overview of the post-DFT methods relevant to materials supporting the ORR and OER reactions. Pt-bearing alloys will then be highlighted with a focus on their application in heterogeneous catalysis and the ORR/OER reactions. The current computational approaches to accurately predicting the band properties of the alloys will then be discussed and both the fundamental and applied importance of this modelling will be highlighted. Full article

Alterations in cellular energy metabolism are a hallmark of cancer and lactate dehydrogenase (LDH) enzymes are overexpressed in many cancers regardless of sufficient oxygen and functional mitochondria. Further, L-lactate plays signaling roles in multiple cell types. We evaluated the effect of singlet oxygen and hypochlorous acid (HOCl) on pig heart LDH-B, which shares 97% homology with human LDH-B. Singlet oxygen was generated photochemically using methylene blue or the chlorophyll metabolites, pheophorbide A and chlorin e6. Singlet oxygen induced protein crosslinks observed by SDS-PAGE under reducing conditions and inhibited LDH-B activity. Ascorbate, hydrocaffeic acid, glutathione and sodium azide were employed as singlet oxygen scavengers and shown to protect LDH-B. Using fluorescein-modified maleimide, no changes in cysteine availability as a result of singlet oxygen damage were observed. This was in contrast to HOCl, which induced the formation of disulfides between LDH-B subunits, thereby decreasing LDH-B labeling with fluorescein. HOCl oxidation inhibited LDH-B activity; however, disulfide reduction did not restore it. LDH-B cysteines were resistant to millimolar H₂O₂, chloramines and Angeli’s salt. In the absence of pyruvate, LDH-B enhanced NADH oxidation in a chain reaction initiated by singlet oxygen that resulted in H₂O₂ formation. Once damaged by either singlet oxygen or HOCl, NADH oxidation by LDH-B was impaired. Full article

Noble gases are a valuable but overlooked source of effective and safe therapeutics. Being monoatomic and chemically inert, they nonetheless have a surprisingly wide range of biochemical and medically valuable properties. This mini review briefly summarizes these properties for the most widely used noble gases and focuses and research gaps and missed opportunities for wider use of these intriguing ‘atomic’ drugs. The main research gaps and opportunities lie firstly in the application of advanced computational modelling methods for noble gases and recent developments in accurate predictions of protein structures from sequence (AlphaFold), and secondly in the use of very efficient and selective drug delivery technologies to improve the solubility, efficacy, and delivery of noble gases to key targets, especially for the lighter, poorly soluble gases. Full article

Bacteria-related infections remain a leading cause of dental implant failures. Despite the successful history of titanium implants, naturally forming oxides lack antibacterial properties. Crystalline oxides, modified through anodization processes, have shown photocatalytic-induced antibacterial properties when exposed to sufficient energy sources such as UVA light. Chemically doping these oxides with some metallic and non-metallic elements has been shown to enhance their photocatalytic activity (PCA). The present study’s objectives were to assess the relative UVA and violet-light-irradiated PCA levels, bacterial attachment levels, and pre-osteoblast early cell viability levels of phosphorus-doped and phosphorus-and-silver-doped anatase-phase oxides. Each oxide revealed similar surface topographies and surface porosity levels. However, the phosphorus-and-silver-doped oxides exhibited significantly higher PCA levels compared to the phosphorus-doped oxide counterpart after irradiation with 365 nm UVA (p < 0.0001) or 410 nm violet (p = 0.007 and 0.03) light. The phosphorus-doped oxides and phosphorus-and-silver-doped oxides revealed similar Staphylococcus aureus attachment levels after 60 min of UVA irradiation. The phosphorus-and-silver-doped oxides exhibited significantly increased 7-day cell viability compared to their phosphorus-doped oxide counterparts. Thus, it was concluded that the silver doping additions to the oxides show much promise for biomaterials applications and warrant further exploration. Full article

The diffusional dynamics and vibrational spectroscopy of molecular hydrogen (H₂) in myoglobin (Mb) is characterized. Hydrogen has been implicated in a number of physiologically relevant processes, including cellular aging or inflammation. Here, the internal diffusion through the protein matrix was characterized, and the vibrational spectroscopy was investigated using conventional empirical energy functions and improved models able to describe higher-order electrostatic moments of the ligand. Depending on the energy function used, H₂ can occupy the same internal defects as already found for Xe or CO (Xe1 to Xe4 and B-state). Furthermore, four additional sites were found, some of which had been discovered in earlier simulation studies. Simulations using a model based on a Morse oscillator and distributed charges to correctly describe the molecular quadrupole moment of H₂ indicate that the vibrational spectroscopy of the ligand depends on the docking site it occupies. This is consistent with the findings for CO in Mb from experiments and simulations. For H₂, the maxima of the absorption spectra cover ∼20 cm⁻¹ which are indicative of a pronounced Stark effect of the surrounding protein matrix on the vibrational spectroscopy of the ligand. Electronic structure calculations show that H₂ forms a stable complex with the heme iron (stabilized by ∼−12 kcal/mol), but splitting of H₂ is unlikely due to a high activation energy (∼50 kcal/mol). Full article

Skin grafting is a critical procedure for treating skin defects from burns, trauma, and surgical interventions, yet complications such as ischemia, necrosis, and infection can limit graft success. Hyperbaric Oxygen Therapy (HBOT) has emerged as a promising adjunctive treatment that enhances skin graft viability through mechanisms including enhanced oxygenation, angiogenesis, reduced inflammation, and anti-infective effects. This review synthesizes findings from clinical studies, comparative analyses, and case reports to clarify HBOT’s efficacy in improving skin graft outcomes. Methods include a comprehensive analysis of HBOT’s impact on graft take rates, healing times, and complication rates. Results indicate that HBOT significantly improves graft survival by mitigating ischemia and infection, while comparative studies show a reduction in major amputations and improved healing in complex cases, such as diabetic foot ulcers and traumatic injuries. These findings suggest that HBOT can serve as a valuable adjunct to standard grafting procedures, offering a multifaceted approach to improve graft viability, especially in high-risk cases. This review highlights HBOT’s potential for integration into wound management protocols, providing a foundation for further exploration into its efficacy and applications in reconstructive surgery. Full article

The success of heated tobacco products (HTPs) and electronic cigarettes (e-cigs) has been largely attributed to their ability to mimic the gestural experience of traditional cigarette smoking, while being perceived as a safer alternative due to the absence of combustion, as well as to their appeal, particularly among younger populations. Despite the initial idea that these new devices were harmless, recent literature reveals a concerning expanding body of evidence on their potential toxicity. Thus, this literature review aims to elucidate the mechanisms by which reactive oxygen species generated by HTPs and e-cigs induce oxidative stress and inflammation and the subsequent biological and health consequences, in order to raise awareness on the significance of addressing the potential toxicological effects associated with these devices, which are commonly believed to be safe. Full article

Evidence suggests that COVID-19 infection increases the risk of type 1 (T1D) and type 2 diabetes (T2D). Diabetes, in turn, increases COVID-19 susceptibility and contributes to increased COVID-19 morbidity and mortality. Oxidative stress has emerged as a common factor driving the pathogenesis of diabetes and COVID-19 caused by the severe acute respiratory syndrome coronavirus. The mechanistic links between oxidative stress, diabetes, and COVID-19 have primarily been studied in adults and will be summarized in this review. However, we suggest that studying these interconnections in children and young adults is critical since early intervention is optimal for improving outcomes. At the height of the pandemic, COVID-19 was a leading cause of death in children and young people, and people in this age group are as susceptible to COVID-19 as adults and the elderly. Glutathione is the primary water-soluble intracellular antioxidant and can be deficient in both diabetes and COVID-19. Glutathione is a tripeptide containing cysteine, glutamic acid, and glycine. Strategies to increase glutathione levels may be beneficial in helping to manage COVID-19-induced diabetes and diabetes-induced COVID-19 risk. Dietary supplementation with glycine plus n-acetyl-l-cysteine may be optimal since it contains two metabolic glutathione precursors. Full article

Cancer remains one of the leading causes of death despite advancements in research and treatment, with traditional therapies often causing significant side effects and resistance. Oxyhydrogen gas, a mixture of 66% molecular hydrogen (H₂) and 33% molecular oxygen (O₂) has shown exceptional promise as a novel therapeutic agent due to its ability to modulate oxidative stress, inflammation, and apoptosis. H₂, a key component of oxyhydrogen gas, neutralises reactive oxygen and nitrogen species, enhancing existing treatments and reducing harmful oxidative states in cancer cells. H₂ also lowers proinflammatory mediators including chemokines, cytokines, and interleukins, inhibiting cancer cell proliferation and boosting the effectiveness of conventional therapies. Additionally, hydrogen can induce apoptosis in cancer cells by modulating pathways such as MAPK and inhibiting the PI3K/Akt phosphorylation cascade. Preclinical and clinical evidence supports oxyhydrogen gas’s potential in treating various cancers. In lung cancer models, it inhibits cell proliferation, induces apoptosis, and enhances chemotherapy sensitivity. Similar results have been observed in breast cancer, where patients reported improved quality of life. In colorectal cancer, oxyhydrogen gas suppresses tumour growth, induces apoptosis, and improves intestinal microflora dysbiosis. The unique properties of oxyhydrogen gas make it a promising adjunctive or standalone cancer treatment. However, further research is needed to understand H₂s’ mechanisms, optimise treatment protocols, and evaluate long-term safety and efficacy in human patients. Full article

Oxidative stress, characterized by an imbalance between the production of reactive oxygen species and the body’s antioxidant defenses, plays an important role in the pathogenesis of various health conditions, including cancer and neurological disorders. For example, excessive ROS can lead to mutations, genomic instability, and uncontrolled cell proliferation in cancer. In neurological disorders, oxidative stress contributes to neuronal damage, inflammation, and the progression of diseases such as Alzheimer’s and Parkinson’s diseases. Adenosine, a nucleoside involved in energy transfer and signal transduction, is crucial to maintaining cellular homeostasis. Its role extends to modulating oxidative stress. Adenosine receptors are implicated in various physiological processes and in the pathophysiology of diseases. The interplay between oxidative stress and adenosine signaling is complex and critical. Adenosine can modulate oxidative stress responses, providing therapeutic potential for conditions where oxidative stress is a key player. Understanding this connection opens up avenues for novel therapeutic strategies targeting adenosine receptors to mitigate oxidative damage. Full article

This study explored the use of mandarin peels as an important source of health-promoting compounds by utilizing green methods (i.e., pulsed electric field and ultrasound-assisted extraction), along with conventional stirring. The impact of several extraction parameters, such as extraction duration, temperature, and solvent composition, on the recovery of bioactive compounds was evaluated through a response surface methodology. To identify the most effective conditions for all assays, a partial least-squares analysis was implemented. It was revealed that a combination of the above techniques was optimal at 80 °C for 30 min, with 75% v/v of ethanol in water as the extraction solvent. The concentration of bioactive compounds in the optimum extract had a total polyphenol content of 18.69 mg of gallic acid equivalents (GAE) per gram of dry weight (dw), and an ascorbic acid concentration of 18.25 mg/g dw. However, correlation analyses revealed a rather negative relationship between these bioactive compounds. The chromatographic analysis of optimum extracts supported this result by quantifying 20.53 mg/g dw of total individual polyphenols, with hesperidin being the dominant compound (13.98 mg/g dw). The antioxidant assays, including ferric-reducing antioxidant power and DPPH^• inhibition activity, were measured at 123.21 and 65.12 μmol of ascorbic acid equivalents (AAE) per gram of dw, respectively. This research enhances the valorization of mandarin peels as a renewable source of bioactive compounds, providing the opportunity to generate high-added-value products from food waste in the food and pharmaceutical sectors. Full article

This study focuses on post-harvest pest management in agriculture, in particular the transition to modified atmospheres as a sustainable alternative to conventional pesticide methods. Using Computational Fluid Dynamics (CFD) simulations, we analysed the dynamics of oxygen distribution within a pest control chamber. We tested four different configurations of nitrogen inlet and outlet positions to determine the most effective setup. The simulations used the twoLiquidMixingFoam solver in OpenFOAM to model gas mixing and diffusion. Our results show that the configuration with the nitrogen inlet at the top and the outlet at the bottom (Case D) was the most efficient. This configuration reached the target oxygen concentration of 1.5% in 4.4 h, significantly faster than the other configurations. These results highlight the importance of inlet and outlet positioning in improving the efficiency of oxygen reduction and ensuring a consistent low oxygen level throughout the chamber. Optimising the placement of nitrogen inlets and outlets has significant potential to improve the effectiveness of modified atmosphere treatments for pest control. Future research should consider additional environmental factors, different storage conditions and insect mortality models to further refine these methods. Full article