A single impact caused temporal and spatial changes to in situ chondrocyte viability with cell shrinkage occurring in the majority of cells. However, chondrocyte shrinkage by raising medium osmolarity at the time of impact protected the cells from injury, whereas swollen chondrocytes were markedly more sensitive. These data showed that chondrocyte volume could be an important determinant of the sensitivity and response of in situ chondrocytes to mechanical stress.

Unpressurized aircraft routinely operate at altitudes where hypoxia may be of concern. A systematic literature review was conducted regarding hypoxic impairment, including mental functions, sensory deficits, and other pertinent research findings that may affect aviation-related duties at moderate altitude (8000 to 15,000 ft/2438 to 4572 m). The results of this review suggest that cognitive and psychomotor deficits may include learning, reaction time, decision-making, and certain types of memory. However, results are difficult to quantify and reliably reproduce. Inconsistency of results may be related to the subtlety of deficits compared to high altitude, differences among individual compensatory mechanisms, variation in methodology or sensitivity of metrics, presence or absence of exercise, heterogeneous neuronal central nervous system (CNS) response, and interindividual variation. Literature regarding hypoxic visual decrements is more consistent. Rod photoreceptors are more susceptible to hypoxia; visual degradation has been demonstrated at 4000 to 5000 ft (1219 to 1524 m) under scotopic and 10,000 ft (3048 m) under photopic conditions. Augmented night vision goggle resolution demonstrates more resilience to mild hypoxic effects than the unaided eye under starlight conditions. Hypocapnia enhances visual sensitivity and contrast discrimination. Hyperventilation with resulting respiratory alkalosis and cerebral vasoconstriction may confound both cognitive/ psychomotor and visual experimental results. Future research should include augmentation of validated neuropsychological metrics (surrogate investigational end points) with actual flight metrics, investigation of mixed gas formulations, contribution of hypocapnic vasoconstrictive effects on hypoxic performance, and further investigation into cellular- and systems-level approaches for heterogeneous CNS response. Research is also required into the contribution of mild-moderate hypoxia in human factors- and spatial disorientation-related mishaps.

Space medicine is fundamental to the human exploration of space. It supports survival, function and performance in this challenging and potentially lethal environment. It is international, intercultural and interdisciplinary, operating at the boundaries of exploration, science, technology and medicine. Space medicine is also the latest UK specialty to be recognized by the Royal College of Physicians in the UK and the General Medical Council. This review introduces the field of space medicine and describes the different types of spaceflight, environmental challenges, associated medical and physiological effects, and operational medical considerations. It will describe the varied roles of the space medicine doctor, including the conduct of surgery and anaesthesia, and concludes with a vision of the future for space medicine in the UK.Space medicine doctors have a responsibility to space workers and spaceflight participants. These 'flight surgeons' are key in developing mitigation strategies to ensure the safety, health and performance of space travellers in what is an extreme and hazardous environment. This includes all phases from selection, training and spaceflight itself to post-flight rehabilitation and long-term health. The recent recognition of the speciality provides a pathway to train in this fascinating field of medicine and is a key enabler for the UK Government's commercial spaceflight ambition.