Underlying lung disease and exposure to terrestrial moderate and high altitude: personalised risk assessment

Can acute high-altitude sickness be predicted in advance?

In high-altitude environments, the oxygen and air density are decreased, and the temperature and humidity are low. When individuals enter high-altitude areas, they are prone to suffering from acute mountain sickness (AMS) because they cannot tolerate hypoxia. Headache, fatigue, dizziness, and gastrointestinal reactions are the main symptoms of AMS. When these symptoms cannot be effectively alleviated, they can progress to life-threatening high-altitude pulmonary edema or high-altitude cerebral edema. If the risk of AMS can be effectively assessed before people enter high-altitude areas, then the high-risk population can be promptly discouraged from entering the area, or drug intervention can be established in advance to prevent AMS occurrence and avoid serious outcomes. This article reviews recent studies related to the early-warning biological indicators of AMS to provide a new perspective on the prevention of AMS.

Skeletal and cardiac muscle have different protein turnover responses in a model of right heart failure

Right heart failure (RHF) is a common and deadly disease in aged populations. Extra-cardiac outcomes of RHF such as skeletal muscle atrophy contribute to morbidity and mortality. Despite the significance of maintaining right ventricular (RV) and muscle function, the mechanisms of RHF and muscle atrophy are unclear. Metformin (MET) improves cardiac and muscle function through the regulation of metabolism and the cellular stress response. However, whether MET is a viable therapeutic for RHF and muscle atrophy is not yet known. We used deuterium oxide labeling to measure individual protein turnover in the RV as well as subcellular skeletal muscle proteostasis in aged male mice subjected to 4 weeks of hypobaric hypoxia (HH)-induced RHF. Mice exposed to HH had elevated RV mass and impaired RV systolic function, neither of which was prevented by MET. HH resulted in a higher content of glycolytic, cardiac, and antioxidant proteins in the RV, most of which were inhibited by MET. The synthesis of these key RV proteins was generally unchanged by MET, suggesting MET accelerated protein breakdown. HH resulted in a loss of skeletal muscle mass due to inhibited protein synthesis alongside myofibrillar protein breakdown. MET did not impact HH-induced muscle protein turnover and did not prevent muscle wasting. Together, we show tissue-dependent responses to HH-induced RHF where the RV undergoes hypertrophic remodeling with higher expression of metabolic and stress response proteins. Skeletal muscle undergoes loss of protein mass and atrophy, primarily due to myofibrillar protein breakdown. MET did not prevent HH-induced RV dysfunction or muscle wasting, suggesting that the identification of other therapies to attenuate RHF and concomitant muscle atrophy is warranted.

Pregnancy and Exercise in Mountain Travelers

ABSTRACT

Pregnant women are traveling to high altitude and evidence-based recommendations are needed. Yet, there are limited data regarding the safety of short-term prenatal high-altitude exposure. There are benefits to prenatal exercise and may be benefits to altitude exposure. Studies evaluating maternofetal responses to exercise at altitude found the only complication was transient fetal bradycardia, a finding of questionable significance. There are no published cases of acute mountain sickness in pregnant women, and data suggesting an increase in preterm labor are of poor quality. Current recommendations across professional societies are overly cautious and inconsistent. Non-evidence-based restrictions to altitude exposure can have negative consequences for a pregnant women's physical, social, mental, and economic health. Available data suggest that risks of prenatal travel to altitude are low. Altitude exposure is likely safe for women with uncomplicated pregnancies. We do not recommend absolute restrictions to high altitude exposure, but rather caution and close self-monitoring.

Exploring predisposing factors and pathogenesis contributing to injuries of donor lungs

INTRODUCTION

Lung transplantation (LTx) remains the only therapeutic strategy for patients with incurable lung diseases. However, its use has been severely limited by the narrow donor pool and potential concerns of inferior quality of donor lungs, which are more susceptible to external influence than other transplant organs. Multiple insults, including various causes of death and a series of perimortem events, may act together on donor lungs and eventually culminate in primary graft dysfunction (PGD) after transplantation as well as other poor short-term outcomes.

AREAS COVERED

This review focuses on the predisposing factors contributing to injuries to the donor lungs, specifically focusing on the pathogenesis of these injuries and their impact on post-transplant outcomes. Additionally, various maneuvers to mitigate donor lung injuries have been proposed.

EXPERT OPINION

The selection criteria for eligible donors vary and may be poor discriminators of lung injury. Not all transplanted lungs are in ideal condition. With the rapidly increasing waiting list for LTx, the trend of using marginal donors has become more apparent, underscoring the need to gain a deeper understanding of donor lung injuries and discover more donor resources.