Oxidative Stress and Inflammation, MicroRNA, and Hemoglobin Variations after Administration of Oxygen at Different Pressures and Concentrations: A Randomized Trial

Consumption of Sylimarin, Pyrroloquinoline Quinone Sodium Salt and Myricetin: Effects on Alcohol Levels and Markers of Oxidative Stress-A Pilot Study

BACKGROUND

Alcohol abuse is one of the most common causes of mortality worldwide. This study aimed to investigate the efficacy of a treatment in reducing circulating ethanol and oxidative stress biomarkers.

METHODS

Twenty wine-drinking subjects were investigated in a randomized controlled, single-blind trial (ClinicalTrials.gov. Identifier: NCT06548503; Ethical Committee of the University of Padova (HEC-DSB/12-2023) to evaluate the effect of the intake of a product containing silymarin, pyrroloquinoline quinone sodium salt, and myricetin (referred to as Si.Pi.Mi. for this project) on blood alcohol, ethyl glucuronide (EtG: marker for alcohol consumption) and markers of oxidative stress levels (Reactive Oxygen Species-ROS, Total Antioxidant Capacity-TAC, CoQ10, thiols redox status, 8-isoprostane, NO metabolites, neopterin, and uric acid). The effects of the treatment versus placebo were evaluated acutely and after 1 week of supplementation in blood and/or saliva and urine samples.

RESULTS

Si.Pi.Mi intake reduced circulating ethanol after 120 min (-33%). Changes in oxidative stress biomarkers, particularly a TAC (range +9-12%) increase and an 8-isoprostane (marker of lipidic peroxidation) decrease (range -22-27%), were observed too.

CONCLUSION

After the administration of Si.Pi.Mi, the data seemed to suggest a better alcohol metabolism and oxidative balance in response to wine intake. Further verification is requested.

Exploring the effects of post operative hyperoxic intermittent stimuli on reticulocyte levels in cancer patients: a randomized controlled study

BACKGROUND

Anemia is common among hospitalized critically ill and surgical oncological patients. The rising incidence of cancer and aggressive treatments has increased the demand for blood products, further strained by a dwindling donor pool. The normobaric oxygen paradox (NOP) has emerged as a potential avenue to increase EPO levels. While some studies support its efficacy, research remains limited in clinical settings. This study aims to assess the effectiveness of a NOP protocol in stimulating erythropoiesis, as measured by changes in reticulocyte counts, in cancer patients undergoing abdominal surgeries.

METHODS

This is a post hoc analysis of a prospective, single-center, controlled, randomized study. A total of 49 patients undergoing abdominal surgery were analyzed at the Institut Jules Bordet. Adult patients admitted to the intensive care unit (ICU) for at least 24 h were enrolled, excluding those with severe renal insufficiency or who received transfusions during the study period. Participants were randomized into two groups: a normobaric oxygen paradox (OXY) group who received 60% oxygen for 2 h on days 1, 3, and 5 post-surgery and a control (CTR) group who received standard care. Data on baseline characteristics, surgical details, and laboratory parameters were collected. Statistical analysis included descriptive statistics, chi-square tests, t-tests, Mann-Whitney tests, and linear and logistic regression.

RESULTS

The final analysis included 33 patients (median age 62 [IQR 58-66], 28 (84.8%) males, with no withdrawals or deaths during the study period. No significant differences were observed in baseline surgical characteristics or perioperative outcomes between the two groups. In the OXY group (n = 16), there was a significant rise (p = 0.0237) in the percentage of reticulocyte levels in comparison to the CTR group (n = 17), with median values of 36.1% (IQR 20.3-57.8) versus - 5.3% (IQR - 19.2-57.8), respectively. The increases in hemoglobin and hematocrit levels did not significantly differ between the groups when compared to their baselines' values.

CONCLUSIONS

This study provides preliminary evidence supporting the potential of normobaric oxygen therapy in stimulating erythropoiesis in cancer patients undergoing abdominal surgeries. While the OXY group resulted in increased reticulocyte counts, further research with larger sample sizes and multi-center trials is warranted to confirm these findings.

TRIAL REGISTRATION

The study was retrospectively registered under NCT number 06321874 on The 10th of April 2024.

Effects of Hyperbaric Oxygen Therapy on Hemogram, Serum Biochemistry and Coagulation Parameters of Dogs Undergoing Elective Laparoscopic-Assisted Ovariohysterectomy

BACKGROUND

This study explored the effects of hyperbaric oxygen therapy (HBOT) on hemogram, serum biochemistry and hemostatic variables in female dogs undergoing laparoscopic-assisted ovariohysterectomy (OVH).

MATERIALS

Thirty adult, mixed-breed, healthy female dogs were randomly divided into the following three groups: HBOT + SURG (exposed to two absolute atmospheres (ATAs) for 45 min followed by laparoscopic-assisted OVH), HBOT (exposed to two ATAs for 45 min) and SURG (laparoscopic-assisted OVH). Blood samples were collected at T0 (at the admission), at T1, 24 h after T0 (immediately after HBOT in the HBOT + SURG and HBOT groups, and immediately before anesthetic premedication in the SURG group), and at T2, 48 h after T0 (24 h after HBOT and anesthetic premedication).

METHODS

Assessments included erythrogram, leukogram, thrombogram, renal and hepatic serum biochemistry, prothrombin time (PT), activated partial thromboplastin time (APTT), buccal mucosal bleeding time (BMBT) and bloodstain area (BA) on hygroscopic paper collected at the BMBT.

RESULTS

Both the HBOT + SURG and SURG groups presented neutrophilia (p ≤ 0.0039) at T2 and an increase of ALP at T2 (p ≤ 0.0493), the SURG group presented an increase in leukocyte count at T2 (p = 0.0238) and the HBOT + SURG group presented a reduction in lymphocyte count at T2 (p = 0.0115). In the HBOT + SURG group, there was a reduction in PT and APTT in relation to the baseline value (p ≤ 0.0412).

CONCLUSIONS

A session of HBOT at two ATAs for 45 min did not cause changes in the BMBT or BA in healthy female dogs. Some blood parameters investigated (neutrophil and lymphocyte count, ALP, PT and APTT) were affected by the use of HBOT.

Effect of Alpha-1 Antitrypsin and Irisin on Post-Exercise Inflammatory Response: A Narrative Review

Physical activity has a positive effect on human health and emotional well-being. However, in both amateur and professional athletes, training poses a risk of acute or chronic injury through repetitive overloading of bones, joints, and muscles. Inflammation can be an adverse effect of intense exercise caused by several factors including oxidative stress. The present narrative review summarizes current knowledge on inflammatory markers induced by physical exercise. Post-exercise recovery may reduce inflammatory responses and is key to effective training and adaptation of muscle tissues to sustained physical exertion.

Pulsed Hyperoxia Acts on Plasmatic Advanced Glycation End Products and Advanced Oxidation Protein Products and Modulates Mitochondrial Biogenesis in Human Peripheral Blood Mononuclear Cells: A Pilot Study on the "Normobaric Oxygen Paradox"

The "normobaric oxygen paradox" (NOP) describes the response to the return to normoxia after a hyperoxic event, sensed by tissues as an oxygen shortage, up-regulating redox-sensitive transcription factors. We have previously characterized the time trend of oxygen-sensitive transcription factors in human PBMCs, in which the return to normoxia after 30% oxygen is sensed as a hypoxic trigger, characterized by hypoxia-induced factor (HIF-1) activation. On the contrary, 100% and 140% oxygen induce a shift toward an oxidative stress response, characterized by NRF2 and NF-kB activation in the first 24 h post exposure. Herein, we investigate whether this paradigm triggers Advanced Glycation End products (AGEs) and Advanced Oxidation Protein Products (AOPPs) as circulating biomarkers of oxidative stress. Secondly, we studied if mitochondrial biogenesis was involved to link the cellular response to oxidative stress in human PBMCs. Our results show that AGEs and AOPPs increase in a different manner according to oxygen dose. Mitochondrial levels of peroxiredoxin (PRX3) supported the cellular response to oxidative stress and increased at 24 h after mild hyperoxia, MH (30% O2), and high hyperoxia, HH (100% O2), while during very high hyperoxia, VHH (140% O2), the activation was significantly high only at 3 h after oxygen exposure. Mitochondrial biogenesis was activated through nuclear translocation of PGC-1α in all the experimental conditions. However, the consequent release of nuclear Mitochondrial Transcription Factor A (TFAM) was observed only after MH exposure. Conversely, HH and VHH are associated with a progressive loss of NOP response in the ability to induce TFAM expression despite a nuclear translocation of PGC-1α also occurring in these conditions. This study confirms that pulsed high oxygen treatment elicits specific cellular responses, according to its partial pressure and time of administration, and further emphasizes the importance of targeting the use of oxygen to activate specific effects on the whole organism.

Hyperoxia: Effective Mechanism of Hyperbaric Treatment at Mild-Pressure

HBOT increases the proportion of dissolved oxygen in the blood, generating hyperoxia. This increased oxygen diffuses into the mitochondria, which consume the majority of inhaled oxygen and constitute the epicenter of HBOT effects. In this way, the oxygen entering the mitochondria can reverse tissue hypoxia, activating the electron transport chain to generate energy. Furthermore, intermittent HBOT is sensed by the cell as relative hypoxia, inducing cellular responses such as the activation of the HIF-1α pathway, which in turn, activates numerous cellular processes, including angiogenesis and inflammation, among others. These effects are harnessed for the treatment of various pathologies. This review summarizes the evidence indicating that the use of medium-pressure HBOT generates hyperoxia and activates cellular pathways capable of producing the mentioned effects. The possibility of using medium-pressure HBOT as a direct or adjunctive treatment in different pathologies may yield benefits, potentially leading to transformative therapeutic advancements in the future.

CNS-oxygen toxicity and blood glucose levels in MnSOD enzyme knockdown mice

Many studies have been conducted in the search for the mechanism underlying CNS-oxygen toxicity (OT), which may be fatal when diving with a closed-circuit apparatus. We investigated the influence of hyperbaric oxygen (HBO) on blood glucose level (BGL) in Mn-superoxide dismutase (SOD2) knockdown mice regarding CNS-OT in particular under stress conditions such as hypoglycemia or hyperglycemia. Two groups of mice were used: SOD2 knockdown (Heterozygous, HET) mice and their WT family littermates. Animals were exposed to HBO from 2 up to 5 atmosphere absolute (ATA). Blood samples were drawn before and after each exposure for measurement of BGL. The mice were sacrificed following the final exposure, which was at 5 ATA. We used RT-PCR and Western blot to measure levels of glucose transporter 1 (GLUT1) and hypoxia inducible factor (HIF)1a in the cortex and hippocampus. In the hypoglycemic condition, the HET mice were more sensitive to oxidative stress than the WT. In addition, following exposure to sub-toxic HBO, which does not induce CNS-OT, BGL were higher in the HET mice compared with the WT. The expression of mRNA of GLUT1 and HIF-1a decreased in the hippocampus in the HET mice, while the protein level decreased in the HET and WT following HBO exposure. The results suggest that the higher BGL following HBO exposure especially at SOD2 HET mice is in part due to reduction in GLUT1 as a consequence of lower HIF-1a expression. This may add part to the puzzle of the understanding the mechanism leading to CNS-OT.

Hyperbaric Oxygen Therapy Counters Oxidative Stress/Inflammation-Driven Symptoms in Long COVID-19 Patients: Preliminary Outcomes

Long COVID-19 patients show systemic inflammation and persistent symptoms such as fatigue and malaise, profoundly affecting their quality of life. Since improving oxygenation can oppose inflammation at multiple tissue levels, we hypothesized that hyperbaric oxygen therapy (HBOT) could arrest inflammation progression and thus relieve symptoms of COVID-19. We evaluated oxy-inflammation biomarkers in long COVID-19 subjects treated with HBOT and monitored with non-invasive methods. Five subjects (two athletes and three patients with other comorbidities) were assigned to receive HBOT: 100% inspired O2 at 2.4 ATA in a multiplace hyperbaric chamber for 90 min (three athletes: 15 HBOT × 5 days/wk for 3 weeks; two patients affected by Idiopathic Sudden Sensorineural Hearing Loss: 30 HBOT × 5 days/wk for 6 weeks; and one patient with osteomyelitis: 30 HBOT × 5 days/wk for week for 6 weeks and, after a 30-day break, followed by a second cycle of 20 HBOT). Using saliva and/or urine samples, reactive oxygen species (ROS), antioxidant capacity, cytokines, lipids peroxidation, DNA damage, and renal status were assessed at T1_pre (basal level) and at T2_pre (basal level after treatment), and the results showed attenuated ROS production, lipid peroxidation, DNA damage, NO metabolites, and inflammation biomarker levels, especially in the athletes post-treatment. Thus, HBOT may represent an alternative non-invasive method for treating long COVID-19-induced long-lasting manifestations of oxy-inflammation.

Effects of hyperbaric oxygen therapy on human psychomotor performance: A review

Psychomotor performance is the coordination of a sensory or ideational (cognitive) process and a motor activity. All sensorimotor processes involved in planning and execution of voluntary movements need oxygen supply and seem to be significantly disrupted in states of hypoxia. Hyperbaric oxygen therapy has become a widely used treatment in routine medicine and sport medicine due to its beneficial effects on different aspects of human physiology and performance. This paper presents state-of-the-art data on the effects of hyperbaric oxygen therapy on different aspects of human psychomotor function. The therapy's influence on musculoskeletal properties and motor abilities as well as the effects of hyperbaric oxygenation on cognitive, myocardial and pulmonary functions are presented. In this review the molecular and physiological processes related to human psychomotor performance in response to hyperbaric oxygen are discussed to contribute to this fast-growing field of research in integrative medicine. Please cite this article as: Olex-Zarychta D. Effects of hyperbaric oxygen therapy on human psychomotor performance: A review. J Integr Med. 2023; 21(5): 430-440.

Oxidative Stress Response Kinetics after 60 Minutes at Different (1.4 ATA and 2.5 ATA) Hyperbaric Hyperoxia Exposures

Hyperbaric oxygen therapy (HBOT) is a therapeutical approach based on exposure to pure oxygen in an augmented atmospheric pressure. Although it has been used for years, the exact kinetics of the reactive oxygen species (ROS) between different pressures of hyperbaric oxygen exposure are still not clearly evidenced. In this study, the metabolic responses of hyperbaric hyperoxia exposures for 1 h at 1.4 and 2.5 ATA were investigated. Fourteen healthy non-smoking subjects (2 females and 12 males, age: 37.3 ± 12.7 years old (mean ± SD), height: 176.3 ± 9.9 cm, and weight: 75.8 ± 17.7 kg) volunteered for this study. Blood samples were taken before and at 30 min, 2 h, 24 h, and 48 h after a 1 h hyperbaric hyperoxic exposure. The level of oxidation was evaluated by the rate of ROS production, nitric oxide metabolites (NOx), and the levels of isoprostane. Antioxidant reactions were assessed through measuring superoxide dismutase (SOD), catalase (CAT), cysteinylglycine, and glutathione (GSH). The inflammatory response was measured using interleukine-6, neopterin, and creatinine. A short (60 min) period of mild (1.4 ATA) and high (2.5 ATA) hyperbaric hyperoxia leads to a similar significant increase in the production of ROS and antioxidant reactions. Immunomodulation and inflammatory responses, on the contrary, respond proportionally to the hyperbaric oxygen dose. Further research is warranted on the dose and the inter-dose recovery time to optimize the potential therapeutic benefits of this promising intervention.

Chelation Therapy Associated with Antioxidant Supplementation Can Decrease Oxidative Stress and Inflammation in Multiple Sclerosis: Preliminary Results

An imbalance of oxy-inflammation status has been involved in axonal damage and demyelination in multiple sclerosis (MS). The aim of this study was to investigate the efficacy of an antioxidant treatment (calcium disodium ethylenediaminetetracetic acid-EDTA) chelation therapy associated with a micronutrient complex in MS patients. A total of 20 MS patients and 20 healthy subjects, enrolled as a control group (CTR), were recruited. We measured the plasma ROS production and total antioxidant capacity (TAC) by a direct assessment using Electron Paramagnetic Resonance; activities of the antioxidant system (thiols' redox status and enzymes); and the urinary presence of biomarkers of oxidative stress by immunoenzymatic assays. We also evaluated the levels of inflammation by plasmatic cytokines (TNFα, IL-1β, and IL-6) and assessed the sICAM levels, as well as the nitric oxide (NO) catabolism and transthyretin (TTR) concentration. Comparing CTR and MS, in the latter ROS production, oxidative damage, inflammatory biomarkers, and NO metabolite concentrations results were significantly higher, while TAC was significantly lower. Treatment in MS induced significant (p < 0.05) down-regulating of pro-inflammatory sICAM1, TNF-α, IL6, as well as biomarkers of lipid peroxidation and DNA damage production. The protective effect exhibited may occur by decreasing ROS production and increasing antioxidant capacity, turning into a more reduced thiols' status.

Oxidative Stress Response Kinetics after 60 Minutes at Different Levels (10% or 15%) of Normobaric Hypoxia Exposure

In this study, the metabolic responses of hypoxic breathing for 1 h to inspired fractions of 10% and 15% oxygen were investigated. To this end, 14 healthy nonsmoking subjects (6 females and 8 males, age: 32.2 ± 13.3 years old (mean ± SD), height: 169.1 ± 9.9 cm, and weight: 61.6 ± 16.2 kg) volunteered for the study. Blood samples were taken before, and at 30 min, 2 h, 8 h, 24 h, and 48 h after a 1 h hypoxic exposure. The level of oxidative stress was evaluated by considering reactive oxygen species (ROS), nitric oxide metabolites (NOx), lipid peroxidation, and immune-inflammation by interleukin-6 (IL-6) and neopterin, while antioxidant systems were observed in terms of the total antioxidant capacity (TAC) and urates. Hypoxia abruptly and rapidly increased ROS, while TAC showed a U-shape pattern, with a nadir between 30 min and 2 h. The regulation of ROS and NOx could be explained by the antioxidant action of uric acid and creatinine. The kinetics of ROS allowed for the stimulation of the immune system translated by an increase in neopterin, IL-6, and NOx. This study provides insights into the mechanisms through which acute hypoxia affects various bodily functions and how the body sets up the protective mechanisms to maintain redox homeostasis in response to oxidative stress.

Mitochondrial Metabolism and EV Cargo of Endothelial Cells Is Affected in Presence of EVs Derived from MSCs on Which HIF Is Activated

Small extracellular vesicles (sEVs) derived from mesenchymal stem cells (MSCs) have attracted growing interest as a possible novel therapeutic agent for the management of different cardiovascular diseases (CVDs). Hypoxia significantly enhances the secretion of angiogenic mediators from MSCs as well as sEVs. The iron-chelating deferoxamine mesylate (DFO) is a stabilizer of hypoxia-inducible factor 1 and consequently used as a substitute for environmental hypoxia. The improved regenerative potential of DFO-treated MSCs has been attributed to the increased release of angiogenic factors, but whether this effect is also mediated by the secreted sEVs has not yet been investigated. In this study, we treated adipose-derived stem cells (ASCs) with a nontoxic dose of DFO to harvest sEVs (DFO-sEVs). Human umbilical vein endothelial cells (HUVECs) treated with DFO-sEVs underwent mRNA sequencing and miRNA profiling of sEV cargo (HUVEC-sEVs). The transcriptomes revealed the upregulation of mitochondrial genes linked to oxidative phosphorylation. Functional enrichment analysis on miRNAs of HUVEC-sEVs showed a connection with the signaling pathways of cell proliferation and angiogenesis. In conclusion, mesenchymal cells treated with DFO release sEVs that induce in the recipient endothelial cells molecular pathways and biological processes strongly linked to proliferation and angiogenesis.

Effect of Hyperbaric oxygen on myelin injury and repair after hypoxic-ischemic brain damage in adult rat

INTRODUCTION

Hypoxic-ischemic encephalopathy (HIE) is one of the leading causes of death and neurological disability with limited options for treatment in neonates, children and adults worldwide. The pathogenesis and treatment of white matter (WM) injury in adult patients with HIE remains largely elusive.

METHODS

Sixty male Sprague-Dawley rats were randomly divided into control group, sham-operated group (HBO treatment 6 days after sham operation), and Hypoxia-ischemia (HI) induced brain damage group (receiving left carotid arteries ligation + hypoxia treatment), 1.5ATA hyperbaric oxygen group (HI + 1.5ATA HBOT) and 2.5ATA HBOT group (HI + 2.5ATA HBOT). All the rats were evaluated by water maze before operation, and 6 days after operation, and the function of learning and memory was evaluated; Demyelination in the hippocampus and prefrontal cortex was observed by Luxol fast blue staining (LFB) and MBP immunostaining; the number of Myelin Oligodendrocyte Glycoprotein (MOG),glial fibrillary acidic protein (GFAP), ionic calcium-binding adaptor (Iba-1) and NG2 positive cells in the hippocampus and prefrontal cortex were determined by immunofluorescence staining. The expression of interleukin-1β (IL-1β), IL-6 and tumor necrosis factor (TNF-α), Hypoxia Inducible Factor 1 Subunit Alpha (HIF1-α) and Superoxide dismutase (SOD) in brain and serum of rats were measured by Western Blot method and Enzyme linked immunosorbent assay (ELISA).

RESULTS

Compared with those in the normal control group and sham-operated group, in the HI group, the learning and memory abilities of rats were significantly decreased (P < 0.05), the intensity of LFB and MBP immunostaining in hippocampus and prefrontal cortex was significantly decreased (P < 0.05); the number of MOG positive oligodendrocytes (OLs) significantly decreased (P < 0.05), whereas the number of Iba-1, GFAP, NG2 positive microglias, astrocytes and oligodendrocyte precursors (OPCs) was increased (P < 0.05); the level of IL-1β, IL-6, TNF-α and HIF-1a in brain and serum were significantly increased (P < 0.05), whereas SOD was significantly decreased in brain and increased in serum. Compared with those in the HI group, in both 1.5ATA and 2.5ATA HBOT group, the learning and memory abilities were significantly increased (P < 0.05); the intensity of LFB and MBP immunostaining in the hippocampus and prefrontal cortex was significantly increased (P < 0.05); the number of MOG positive OLs significantly increased (P < 0.05); the number of Iba-1, GFAP, NG2 positive microglias, astrocytes and OPCs was decreased (P < 0.05); the level of IL-1β, IL-6, TNF-α and HIF-1a in brain and serum were significantly decreased (P < 0.05); the level of SOD was significantly increased in brain and decreased in serum. Morever, compared with those in the 1.5ATA group, 2.5ATA provided better treatment results (P < 0.05).

CONCLUSION

In the present study, we demonstrated the mechanism of different pressure HBOT on HI induced brain injury from three levels: (1) On a tissue level, HBOT protects against HI induced myelin injury; (2) On a cellular level, HBOT attenuates HI-induced OL loss, suppresss the reactive activation of astrocyte and microglia, and may promote OPC to differentiate into OL; (3) On a molecular level, HBOT inhibites neuroinflammation, and balances oxidative damage and antioxidant capacity. Among the above effects, 2.5ATA HBOT is better than 1.5ATA HBOT. Ongoing research will continue to seek out the signalling pathways and molecules mechanisms on different pressure of HBOT-related myelin protection, and possibly expand suitable HBOT use in adult HIE clinically.

Playing with Biophysics: How a Symphony of Different Electromagnetic Fields Acts to Reduce the Inflammation in Diabetic Derived Cells

Several factors, such as ischemia, infection and skin injury impair the wound healing process. One common pathway in all these processes is related to the reactive oxygen species (ROS), whose production plays a vital role in wound healing. In this view, several strategies have been developed to stimulate the activation of the antioxidative system, thereby reducing the damage related to oxidative stress and improving wound healing. For this purpose, complex magnetic fields (CMFs) are used in this work on fibroblast and monocyte cultures derived from diabetic patients in order to evaluate their influence on the ROS production and related wound healing properties. Biocompatibility, cytotoxicity, mitochondrial ROS production and gene expression have been evaluated. The results confirm the complete biocompatibility of the treatment and the lack of side effects on cell physiology following the ISO standard indication. Moreover, the results confirm that the CMF treatment induced a reduction in the ROS production, an increase in the macrophage M2 anti-inflammatory phenotype through the activation of miRNA 5591, a reduction in inflammatory cytokines, such as interleukin-1 (IL-1) and IL-6, an increase in anti-inflammatory ones, such as IL-10 and IL-12 and an increase in the markers related to improved wound healing such as collagen type I and integrins. In conclusion, our findings encourage the use of CMFs for the treatment of diabetic foot.

Dopamine/BDNF loss underscores narcosis cognitive impairment in divers: a proof of concept in a dry condition

PURPOSE

Divers can experience cognitive impairment due to inert gas narcosis (IGN) at depth. Brain-derived neurotrophic factor (BDNF) rules neuronal connectivity/metabolism to maintain cognitive function and protect tissues against oxidative stress (OxS). Dopamine and glutamate enhance BDNF bioavailability. Thus, we hypothesized that lower circulating BDNF levels (via lessened dopamine and/or glutamate release) underpin IGN in divers, while testing if BDNF loss is associated with increased OxS.

METHODS

To mimic IGN, we administered a deep narcosis test via a dry dive test (DDT) at 48 msw in a multiplace hyperbaric chamber to six well-trained divers. We collected: (1) saliva samples before DDT (T0), 25 msw (descending, T1), 48 msw (depth, T2), 25 msw (ascending, T3), 10 min after decompression (T4) to dopamine and/or reactive oxygen species (ROS) levels; (2) blood and urine samples at T0 and T4 for OxS too. We administered cognitive tests at T0, T2, and re-evaluated the divers at T4.

RESULTS

At 48 msw, all subjects experienced IGN, as revealed by the cognitive test failure. Dopamine and total antioxidant capacity (TAC) reached a nadir at T2 when ROS emission was maximal. At decompression (T4), a marked drop of BDNF/glutamate content was evidenced, coinciding with a persisting decline in dopamine and cognitive capacity.

CONCLUSIONS

Divers encounter IGN at - 48 msw, exhibiting a marked loss in circulating dopamine levels, likely accounting for BDNF-dependent impairment of mental capacity and heightened OxS. The decline in dopamine and BDNF appears to persist at decompression; thus, boosting dopamine/BDNF signaling via pharmacological or other intervention types might attenuate IGN in deep dives.

Oxidative Stress Response's Kinetics after 60 Minutes at Different (30% or 100%) Normobaric Hyperoxia Exposures

Oxygen is a powerful trigger for cellular reactions and is used in many pathologies, including oxidative stress. However, the effects of oxygen over time and at different partial pressures remain poorly understood. In this study, the metabolic responses of normobaric oxygen intake for 1 h to mild (30%) and high (100%) inspired fractions were investigated. Fourteen healthy non-smoking subjects (7 males and 7 females; age: 29.9 ± 11.1 years, height: 168.2 ± 9.37 cm; weight: 64.4 ± 12.3 kg; BMI: 22.7 ± 4.1) were randomly assigned in the two groups. Blood samples were taken before the intake at 30 min, 2 h, 8 h, 24 h, and 48 h after the single oxygen exposure. The level of oxidation was evaluated by the rate of reactive oxygen species (ROS) and the levels of isoprostane. Antioxidant reactions were observed by total antioxidant capacity (TAC), superoxide dismutase (SOD), and catalase (CAT). The inflammatory response was measured using interleukin-6 (IL-6), neopterin, creatinine, and urates. Oxidation markers increased from 30 min on to reach a peak at 8 h. From 8 h post intake, the markers of inflammation took over, and more significantly with 100% than with 30%. This study suggests a biphasic response over time characterized by an initial "permissive oxidation" followed by increased inflammation. The antioxidant protection system seems not to be the leading actor in the first place. The kinetics of enzymatic reactions need to be better studied to establish therapeutic, training, or rehabilitation protocols aiming at a more targeted use of oxygen.

Diagnostic Performance of Circulating miRNAs and Extracellular Vesicles in Acute Ischemic Stroke

Background: Increased inflammation activates blood coagulation system, higher platelet activation plays a key role in the pathophysiology of ischemic stroke (IS). During platelet activation and aggregation process, platelets may cause increased release of several proinflammatory, and prothrombotic mediators, including microRNAs (miRNAs) and extracellular vesicles (EVs). In the current study we aimed to assess circulating miRNAs profile related to platelet function and inflammation and circulating EVs from platelets, leukocytes, and endothelial cells to analyse their diagnostic and predictive utility in patients with acute IS. Methods: The study population consisted of 28 patients with the diagnosis of the acute IS. The control group consisted of 35 age- and gender-matched patients on acetylsalicylic acid (ASA) therapy without history of stroke and/or TIA with established stable coronary artery disease (CAD) and concomitant cardiovascular risk factors. Venous blood samples were collected from the control group and patients with IS on ASA therapy (a) 24 h after onset of acute IS, (b) 7-days following index hospitalization. Flow cytometry was used to determine the concentration of circulating EVs subtypes (from platelets, leukocytes, and endothelial cells) in platelet-depleted plasma and qRT-PCR was used to determine several circulating plasma miRNAs (miR-19a-3p, miR-186-5p and let-7f). Results: Patients with high platelet reactivity (HPR, based on arachidonic acid-induced platelet aggregometry) had significantly elevated platelet-EVs (CD62+) and leukocyte-EVs (CD45+) concentration compared to patients with normal platelet reactivity at the day of 1 acute-stroke (p = 0.012, p = 0.002, respectively). Diagnostic values of baseline miRNAs and EVs were evaluated with receiver operating characteristic (ROC) curve analysis. The area under the ROC curve for miR-19a-3p was 0.755 (95% CI, 0.63–0.88) p = 0.004, for let-7f, it was 0.874 (95% CI, 0.76–0.99) p = 0.0001; platelet-EVs was 0.776 (95% CI, 0.65–0.90) p = 0.001, whereas for leukocyte-EVs, it was 0.715 (95% CI, 0.57–0.87) p = 0.008. ROC curve showed that pooling the miR-19a-3p expressions, platelet-EVs, and leukocyte-EVs concentration yielded a higher AUC than the value of each individual biomarker as AUC was 0.893 (95% CI, 0.79–0.99). Patients with moderate stroke had significantly elevated miR-19a-3p expression levels compared to patients with minor stroke at the first day of IS. (AUC: 0.867, (95% CI, 0.74–0.10) p = 0.001). Conclusion: Combining different biomarkers of processes underlying IS pathophysiology might be beneficial for early diagnosis of ischemic events. Thus, we believe that in the future circulating biomarkers might be used in the prehospital phase of IS. In particular, circulating plasma EVs and non-coding RNAs including miRNAs are interesting candidates as bearers of circulating biomarkers due to their high stability in the blood and making them highly relevant biomarkers for IS diagnostics.

Effects of hyperoxemia on aneurysmal subarachnoid hemorrhage outcomes: a systematic review and meta-analysis

OBJECTIVE

In recent years, hyperoxemia in the intensive care unit has received attention as potentially contributing to negative outcomes in the setting of cardiac arrest, ischemic stroke, and traumatic brain injury. The authors sought to evaluate whether hyperoxemia contributes to worse outcomes in the setting of aneurysmal subarachnoid hemorrhage (aSAH) and to summarize suggested pathophysiological mechanisms.

METHODS

A systematic literature review was conducted without date restrictions on the PubMed and Web of Science databases on September 15, 2021. All studies that assessed the relationship between patients treated for aSAH and hyperoxemia were eligible independent of the criteria used to define hyperoxemia. All nonclinical studies and studies that did not report outcome data specific to patients with aSAH were excluded. A total of 102 records were found and screened, resulting in assessment of 10 full-text studies, of which 7 met eligibility criteria. Risk of bias was assessed using the Downs and Black checklist. A meta-analysis on the pooled 2602 patients was performed, and forest plots were constructed. Additionally, a review of the literature was performed to summarize available data regarding the pathophysiology of hyperoxemia.

RESULTS

The included studies demonstrated an association between hyperoxemia and increased morbidity and mortality following aSAH. The criteria used to determine hyperoxemia varied among studies. Pooling of univariate data showed hyperoxemia to be associated with poor neurological outcome (OR 2.26, 95% CI 1.66-3.07; p < 0.001), delayed cerebral ischemia (DCI) (OR 1.91, 95% CI 1.31-2.78; p < 0.001), and increased incidence of poor neurological outcome or mortality as a combined endpoint (OR 2.36, 95% CI 1.87-2.97; p < 0.001). Pooling of multivariable effect sizes showed the same relationship for poor neurological outcome (OR 1.28, 95% CI 1.07-1.55; p = 0.01) and poor neurological outcome and mortality as a combined endpoint (OR 1.17, 95% CI 1.11-1.23; p < 0.001). Additionally, review of preclinical studies underlined the contribution of oxidative stress due to hyperoxemia to acute secondary brain injury and DCI.

CONCLUSIONS

Reported outcomes from the available studies have indicated that hyperoxemia is associated with worse neurological outcome, mortality, and DCI. These findings provide a general guideline toward avoiding hyperoxemia in the acute setting of aSAH. Further studies are needed to determine the optimal ventilation and oxygenation parameters for acute management of this patient population.

Potential Advances of Adjunctive Hyperbaric Oxygen Therapy in Infective Endocarditis

Patients with infective endocarditis (IE) form a heterogeneous group by age, co-morbidities and severity ranging from stable patients to patients with life-threatening complications with need for intensive care. A large proportion need surgical intervention. In-hospital mortality is 15-20%. The concept of using hyperbaric oxygen therapy (HBOT) in other severe bacterial infections has been used for many decades supported by various preclinical and clinical studies. However, the availability and capacity of HBOT may be limited for clinical practice and we still lack well-designed studies documenting clinical efficacy. In the present review we highlight the potential beneficial aspects of adjunctive HBOT in patients with IE. Based on the pathogenesis and pathophysiological conditions of IE, we here summarize some of the important mechanisms and effects by HBOT in relation to infection and inflammation in general. In details, we elaborate on the aspects and impact of HBOT in relation to the host response, tissue hypoxia, biofilm, antibiotics and pathogens. Two preclinical (animal) studies have shown beneficial effect of HBOT in IE, but so far, no clinical study has evaluated the feasibility of HBOT in IE. New therapeutic options in IE are much needed and adjunctive HBOT might be a therapeutic option in certain IE patients to decrease morbidity and mortality and improve the long-term outcome of this severe disease.

The Effect of Hyperbaric Oxygen Therapy on Markers of Oxidative Stress and the Immune Response in Healthy Volunteers

Hyperbaric oxygen therapy (HBOT) consists of breathing 100% oxygen under increased ambient pressure. There are indications that HBOT induces oxidative stress and activates immune pathways. However, previous research on immunological effects of HBOT has mainly been established in in vitro experiments and selected patient populations, limiting generalizability and increasing the chances of confounding by comorbidities and specific patient-related factors. More insight into the immunological effects of HBOT would aid investigation and comprehension of potentially novel treatment applications. Therefore, in this study, we investigated the effects of three 110-min HBOT-sessions with 24-h intervals on immunological parameters in healthy, young, male volunteers. Blood samples were obtained before and after the first and third HBOT sessions. We assessed neutrophilic reactive oxygen species (ROS) production, systemic oxidative stress [plasma malondialdehyde (MDA) concentrations] as well as neutrophil phagocytic activity, plasma concentrations of tumor necrosis factor (TNF), interleukin (IL)-6, IL-8, and IL-10, and production of TNF, IL-6, and IL-10 by leukocytes ex vivo stimulated with the Toll-like receptor (TLR) ligands lipopolysaccharide (TLR4) and Pam3Cys (TLR2). We observed decreased neutrophilic ROS production and phagocytosis following the second HBOT session, which persisted after the third session, but no alterations in MDA concentrations. Furthermore, plasma concentrations of the investigated cytokines were unaltered at all-time points, and ex vivo cytokine production was largely unaltered over time as well. These results indicate no induction of systemic oxidative stress or a systemic inflammatory response after repeated HBOT in healthy volunteers but may suggest exhaustion of ROS generation capacity and phagocytosis.

Full-Face Mask Use during SCUBA Diving Counters Related Oxidative Stress and Endothelial Dysfunction

Impaired flow mediated dilation (FMD), an index of vascular stress, is known after SCUBA diving. This is related to a dysfunction of nitric oxide (NO) availability and a disturbance of the redox status, possibly induced by hyperoxic/hyperbaric gas breathing. SCUBA diving is usually performed with a mask only covering “half face” (HF) and therefore forcing oral breathing. Nasal NO production is involved in vascular homeostasis and, as consequence, can significantly reduce NO possibly promoting vascular dysfunction. More recently, the utilization of “full-face” (FF) mask, allowing nasal breathing, became more frequent, but no reports are available describing their effects on vascular functions in comparison with HF masks. In this study we assessed and compared the effects of a standard shallow dive (20 min at 10 m) wearing either FF or a HF mask on different markers of vascular function (FMD), oxidative stress (ROS, 8-iso-PGF2α) and NO availability and metabolism (NO₂, NOx and 3-NT and iNOS expression). Data from a dive breathing a hypoxic (16% O₂ at depth) gas mixture with HF mask are shown allowing hyperoxic/hypoxic exposure. Our data suggest that nasal breathing might significantly reduce the occurrence of vascular dysfunction possibly due to better maintenance of NO production and bioavailability, resulting in a better ability to counter reactive oxygen and nitrogen species. Besides the obvious outcomes in terms of SCUBA diving safety, our data permit a better understanding of the effects of oxygen concentrations, either in normal conditions or as a strategy to induce selected responses in health and disease.

Hyperbaric Oxygen Treatment: Effects on Mitochondrial Function and Oxidative Stress

Hyperbaric oxygen treatment (HBOT)—the administration of 100% oxygen at atmospheric pressure (ATA) greater than 1 ATA—increases the proportion of dissolved oxygen in the blood five- to twenty-fold. This increase in accessible oxygen places the mitochondrion—the organelle that consumes most of the oxygen that we breathe—at the epicenter of HBOT’s effects. As the mitochondrion is also a major site for the production of reactive oxygen species (ROS), it is possible that HBOT will increase also oxidative stress. Depending on the conditions of the HBO treatment (duration, pressure, umber of treatments), short-term treatments have been shown to have deleterious effects on both mitochondrial activity and production of ROS. Long-term treatment, on the other hand, improves mitochondrial activity and leads to a decrease in ROS levels, partially due to the effects of HBOT, which increases antioxidant defense mechanisms. Many diseases and conditions are characterized by mitochondrial dysfunction and imbalance between ROS and antioxidant scavengers, suggesting potential therapeutic intervention for HBOT. In the present review, we will present current views on the effects of HBOT on mitochondrial function and oxidative stress, the interplay between them and the implications for several diseases.

Oxygen: A Stimulus, Not “Only” a Drug

Depending on the oxygen partial pressure in a tissue, the therapeutic effect of oxygenation can vary from simple substance substitution up to hyperbaric oxygenation when breathing hyperbaric oxygen at 2.5–3.0 ATA. Surprisingly, new data showed that it is not only the oxygen supply that matters as even a minimal increase in the partial pressure of oxygen is efficient in triggering cellular reactions by eliciting the production of hypoxia-inducible factors and heat-shock proteins. Moreover, it was shown that extreme environments could also interact with the genome; in fact, epigenetics appears to play a major role in extreme environments and exercise, especially when changes in oxygen partial pressure are involved. Hyperbaric oxygen therapy is, essentially, “intermittent oxygen” exposure. We must investigate hyperbaric oxygen with a new paradigm of treating oxygen as a potent stimulus of the molecular network of reactions.