Hypoxia, Brain

Traumatic brain injury (TBI) and other conditions that reduce blood flow to the brain - such as cardiac arrest (CA) - are life-threatening medical emergencies. When brain cells are damaged, they release specific proteins into the bloodstream. These proteins, called neurobiomarkers, can be measured in blood samples and may help doctors assess the severity of brain injury, guide treatment, and predict patient outcomes. A major gap in current knowledge is how these neurobiomarkers behave during the very first minutes and hours after injury - the so-called "hyperacute" phase - especially when patients are still being treated by paramedics or have just arrived at the emergency department (ED). It is not yet clear whether biomarker levels rise immediately at the moment of injury or gradually over time, and how quickly they can be reliably detected. The CHARON study investigates the time-dependent kinetics of key neurobiomarkers - including S100B, glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), neurofilament light chain (NFL), and Tau proteins- during the hyperacute phase of acute brain injury. In addition to these proteins, microRNAs, polar metabolites, and lipid metabolites are also examined as potential biomarkers. The study enrolls three groups of participants: * Patients with severe traumatic brain injury and/or polytrauma treated in the prehospital setting and admitted to the ED with T1 (highest priority) triage classification. * Patients with CA treated (resuscitated) in the prehospital setting. * Patients with severe traumatic brain injury enrolled at hospital (ED) admission. Serial blood samples are collected at multiple time points, beginning during prehospital care and continuing through the first 24 hours of hospital admission. No experimental treatments are given - all participants receive standard medical care. By analyzing biomarker concentration and kinetics across all three groups and correlating findings with neurological outcome at 30 days, the investigators aim to identify the most clinically effective neurobiomarkers for early diagnosis and prognosis of acute brain injury. The study is a prospective multi-center investigation conducted at emergency departments, intensive care units, and ambulance services across Hungary.

This study will evaluate the sensitivity and specificity of low field portable MRI (pMRI) for detection of hypoxic ischemic brain injuries in pediatric patients compared to clinically obtained neuroimaging to define pediatric diagnostic limitations and to determine the diagnostic capabilities of this neuroimaging modality following optimization of image acquisition. The results of this study will help determine optimal clinical implementation opportunities in pediatric patients.

High-grade gliomas (HGGs) are the most common type of brain cancer in adults. Life expectancy for patients with HGGs is low. Radiotherapy aims to cure the tumour, but this is hard because HGGs are resistant to treatment. Among the possible causes of resistance may be tumour cells with low-oxygen levels (hypoxia). The investigators know that hypoxia reduces tumour sensitivity to radiotherapy. Using a special imaging technique called oxygen-enhanced MRI (OE-MRI), the investigators can try to identify areas of the tumour with hypoxia. The investigators could then give those areas a higher dose of radiotherapy. This might improve tumour control. This study aims to see if OE-MRI can find low-oxygen areas in HGGs. The study will also assess whether higher radiotherapy doses can be simulated in these regions. Project summary: 1. Set up the OE-MRI process at Leeds Cancer Centre (LCC). OE-MRI settings will be tested on healthy volunteer participants to ensure the images are as good as possible. 2. Participant Imaging. Patient participants with HGG will be recruited to take part. OE-MRI will be used to image participants during their treatment and track low-oxygen areas before treatment, halfway through treatment and 3 months after treatment has finished. 3. Dose Escalation Assessment. Computer programs will be used to design radiotherapy treatments to test if higher radiation doses to the tumour's low-oxygen areas can better control the cancer. This will help understand if this targeted approach has potential benefits. This is modelling and will not alter routine clinical patient participant management.

The goal of this study is to investigate whether prospective memory, i.e., memory for delayed intentions, is impaired at moderate altitude (4,000m). It will also allow to study the effect of air and oxygen administration during hypoxia exposure. The main questions it aims to answer are: * Does moderate acute hypoxia impair prospective memory ? * If so, does air or oxygen adminsitration induce a restoration of prospective memory? Researchers will compare cognitive performance during normobaric hypoxia exposure to cognitive performance during normoxia (control situation). Participants will: * Session S0. Perform a battery of neuropsychological tests and questionnaires). EEG will be recorded during tests. A cheek swab will be performed. * Sessions S1 and S2. Perform several cognitive tasks while exposed to hypoxia and to normoxia (2 different sessions, randomized order) in a normobaric chamber. These are standardized cognitive tests administered on a computer and cognitive tests embedded in a flight simulator scenario. Various questionnaires will be performed on a regular basis. Several physiological measurements will be performed continuously: EEG, ECG, SpO2 and breathing rate. Blood pressure will be measured at the beginning and at the end of hypoxia/normoxia exposure. A blood sample will also be performed. At last, participants will inhale air or oxygen through a mask while making a cognitive task in the chamber.

A prospective double blind, placebo-controlled, randomized cross-over trial to evaluate the effect of lowering cerebral blood flow on the ventilatory chemoreflexes (acute hypoxic and hypercapnic ventilatory responses).

To provide detailed information on long-term outcomes in relation to potential neuroprotection and improvements in recovery for different targets of sedation, temperature, and pressure management in post out of hospital cardiac arrest survivors at 6 and 12 months. In addition, the impact of caring for a post OHCA survivor will be explored.