Hypoxia, Brain

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.

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.

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.