Introduction Cancer is affecting a growing number of persons. Still, the treatment and survival of cancer is improving. Radiation therapy is used in the treatment of cancer. Late radiation-induced injuries afflict 5-15% of irradiated patients. The urinary bladder and bowel may be affected after irradiation of cancer in the pelvic region. Symptoms can be severe, with impaired health related quality of life (HRQoL). Hyperbaric oxygen therapy (HBOT) involves breathing oxygen at high ambient pressure. HBOT can reverse radiation-induced injuries, alleviate patient-perceived symptoms, and improve HRQoL. We aimed to clarify the effects of HBOT on late radiation-induced injuries in the urinary bladder and bowel, and to clarify some of the underlying mechanisms through which HBOT exerts its effects. Methods A prospective cohort study assessed effects of HBOT on patient-perceived symptoms (Paper I). A rat study assessed reversal of radiation-induced stress with HBOT (Paper II). A methodological experiment assessed reversal of HBOT on cellular death induced by radiation (Paper III). A multi-center, randomized, controlled trial assessed patient-perceived symptoms, HRQoL, and objective clinical outcomes (Paper IV). Result HBOT can alleviate patient-perceived symptoms, reduce objective findings, and improve HRQoL in patients affected by late radiation-induced injuries (Paper I, IV). Oxidative stress and downstream effects, induced by the irradiation, can be reversed by HBOT (Paper II). Paper III outlines a method for studies on urothelial cells exposed to radiation and HBOT. Conclusion HBOT can reduce radiation-induced oxidative stress and inflammatory response. HBOT can reverse injuries induced by radiation therapy to the pelvic region, alleviate patient-perceived symptoms and lead to improved HRQoL.

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IntroductionCOVID-19 may cause severe pneumonitis and trigger a massive inflammatory response that requires ventilatory support. The intensive care unit (ICU)-mortality has been reported to be as high as 62%. Dexamethasone is the only of all anti-inflammatory drugs that have been tested to date that has shown a positive effect on mortality. We aim to explore if treatment with hyperbaric oxygen (HBO) is safe and effective for patients with severe COVID-19. Our hypothesis is that HBO can prevent ICU admission, morbidity and mortality by attenuating the inflammatory response. The primary objective is to evaluate if HBO reduces the number of ICU admissions compared with best practice treatment for COVID-19, main secondary objectives are to evaluate if HBO reduces the load on ICU resources, morbidity and mortality and to evaluate if HBO mitigates the inflammatory reaction in COVID-19.Methods and analysisA randomised, controlled, phase II, open label, multicentre trial. 200 subjects with severe COVID-19 and at least two risk factors for mortality will be included. Baseline clinical data and blood samples will be collected before randomisation and repeated daily for 7 days, at days 14 and 30. Subjects will be randomised with a computer-based system to HBO, maximum five times during the first 7 days plus best practice treatment or only best practice treatment. The primary endpoint, ICU admission, is defined by criteria for selection for ICU. We will evaluate if HBO mitigates the inflammatory reaction in COVID-19 using molecular analyses. All parameters are recorded in an electronic case report form. An independent Data Safety Monitoring Board will review the safety parameters.Ethics and disseminationThe trial is approved by The National Institutional Review Board in Sweden (2020-01705) and the Swedish Medical Product Agency (5.1-2020-36673). Positive, negative and any inconclusive results will be published in peer-reviewed scientific journals with open access.Trial registrationNCT04327505. EudraCT number: 2020-001349-37.

Increased concentrations of tau protein are associated with medical conditions involving the central nervous system, such as Alzheimer's disease, traumatic brain injury and hypoxia. Diving, by way of an elevated ambient pressure, can affect the nervous system, however it is not known whether it causes a rise in tau protein levels in serum. A prospective observational pilot study was performed to investigate changes in tau protein concentrations in serum after diving and also determine their relationship, if any, to the amount of inert gas bubbling in the venous blood. Methods: Subjects were 10 navy divers performing one or two dives per day, increasing in depth, over four days. Maximum dive depths ranged from 52-90 metres' sea water (msw). Air or trimix (nitrogen/oxygen/helium) was used as the breathing gas and the oxygen partial pressure did not exceed 160 kPa. Blood samples taken before the first and after the last dives were analyzed. Divers were monitored for the presence of venous gas emboli (VGE) at 10 to 15 minute intervals for up to 120 minutes using precordial Doppler ultrasound. Results: Median tau protein before diving was 0.200 pg•mL-1 (range 0.100 to 1.10 pg•mL-1) and after diving was 0.450 pg•mL-1 (range 0.100 to 1.20 pg•mL-1 ; P = 0.016). Glial fibrillary acidic protein and neurofilament light protein concentrations analyzed in the same assay did not change after diving. No correlation was found between serum tau protein concentration and the amount of VGE. Conclusion: Repeated diving to between 52-90 msw is associated with a statistically significant increase in serum tau protein concentration, which could indicate neuronal stress.