Search

Acute mountain sickness (AMS) occurs when there is failure of acclimatisation to high altitude. The aim of this study was to describe the relationship between physiological variables and the incidence of AMS during ascent to 5300 m. A total of 332 lowland‐dwelling volunteers followed an identical ascent profile on staggered treks. Self‐reported symptoms of AMS were recorded daily using the Lake Louise score (mild 3–4; moderate‐severe ≥5), alongside measurements of physiological variables (heart rate, respiratory rate (RR), peripheral oxygen saturation (SpO2) and blood pressure) before and after a standardised Xtreme Everest Step‐Test (XEST). The overall occurrence of AMS among participants was 73.5% (23.2% mild, 50.3% moderate–severe). There was no difference in gender, age, previous AMS, weight or body mass index between participants who developed AMS and those who did not. Participants who had not previously ascended >5000 m were more likely to get moderate‐to‐severe AMS. Participants who suffered moderate‐to‐severe AMS had a lower resting SpO2 at 3500 m (88.5 vs. 89.6%, p = 0.02), while participants who suffered mild or moderate‐to‐severe AMS had a lower end‐exercise SpO2 at 3500 m (82.2 vs. 83.8%, p = 0.027; 81.5 vs. 83.8%, p 5000 m (OR 2.740, p‐value 0.003) predicted the development of moderate‐to‐severe AMS. The Xtreme Everest Step‐Test offers a simple, reproducible field test to help predict AMS, albeit with relatively limited predictive precision., We evaluated the performance of a simple exercise challenge at altitude (the Xtreme Everest Step‐Test) in predicting acute mountain sickness (AMS) on a trek to Everest Base Camp (5300 m). The overall occurrence of AMS during the trek was high (73.5%). Lower peripheral oxygen saturation (SpO2) following the Xtreme Everest Step‐Test at 3500 m and no previous exposure to altitude >5000 m predicted the development of moderate to severe AMS (Lake Louise score ≥5) during the trek. The Xtreme Everest Step‐Test offers a simple, reproducible field test to contribute towards the prediction of AMS, albeit with relatively limited predictive precision.

Myeloid cell leukemia-1 (MCL-1) is an anti-apoptotic BCL-2 protein that is up-regulated in several human cancers. MCL-1 is also highly expressed in myocardium, but its function in myocytes has not been investigated. We generated inducible, cardiomyocyte-specific Mcl-1 knockout mice and found that ablation of Mcl-1 in the adult heart led to rapid cardiomyopathy and death. Although MCL-1 is known to inhibit apoptosis, this process was not activated in MCL-1-deficient hearts. Ultrastructural analysis revealed disorganized sarcomeres and swollen mitochondria in myocytes. Mitochondria isolated from MCL-1-deficient hearts exhibited reduced respiration and limited Ca2+-mediated swelling, consistent with opening of the mitochondrial permeability transition pore (mPTP). Double-knockout mice lacking MCL-1 and cyclophilin D, an essential regulator of the mPTP, exhibited delayed progression to heart failure and extended survival. Autophagy is normally induced by myocardial stress, but induction of autophagy was impaired in MCL-1-deficient hearts. These data demonstrate that MCL-1 is essential for mitochondrial homeostasis and induction of autophagy in the heart. This study also raises concerns about potential cardiotoxicity for chemotherapeutics that target MCL-1.

The optical counterpart of the new transient X-ray source, GRS 1121-68, Nova Muscae 1991, has been identified. The optical position, the optical lightcurve, and two early-stage flux calibrated spectra are reported. The available data support the binary nature of Nova Muscae 1991. Similarity with A0620-00 in its early evolutionary stages suggests that Nova Muscae 1991 is a possible black hole candidate.