High altitude medicine and biology in China (p. 1)

There has been a tremendous burgeoning of research on high altitude medicine and biology in China. In fact it is probable that there is more research in this country than anywhere else in the world. Nevertheless there are some worrying trends.

Sightings, Edited by Peter Bärtsch and Erik Swenson (p. 3)

Clinician's Corner, Edited by Andrew Luks

Hormonal contraceptives and travel to high altitude

Linda Keyes (p. 7) provides an authoritative update on this important topic for women.

Exaggerated hypoxic pulmonary vasoconstriction without susceptibility to high altitude pulmonary edema

It has been known for some time that patients who develop high altitude pulmonary edema (HAPE) have an increased hypoxic pulmonary vasoconstriction response and elevated pulmonary artery pressures at high altitude. Dehnert and colleagues (p. 11) studied 33 subjects who had hypoxic pulmonary vasoconstriction and ascended within 24 hours to 4559 m. However the incidence of HAPE was significantly lower than that observed in HAPE-susceptible subjects. They concluded that while a high pulmonary artery pressure is necessary for the development of HAPE, it is not sufficient. Some other factor is involved. Presumably this is unevenness of the vasoconstrictor response within the lung

Cerebral water and ion-balance remains stable when humans are exposed to acute hypoxic exercise

Avnstorp et al. (p. 18) note that one hypothesis for the pathogenesis of acute mountain sickness is cerebral edema. In this study, subjects exercised on a cycle ergometer for 30 minutes during air breathing or 10% oxygen. Cerebral net water and homeostasis of sodium and potassium ions remained stable.

Association between serum concentrations of hypoxia-inducible factor responsive proteins and excessive erythrocytosis in high altitude Peru

Chronic mountain sickness is a serious problem for permanent residents of high altitude. It is characterized by excessive erythrocytosis which may be influenced by overrepresentation of variants of the EPAS1 gene that codes for hypoxia-inducible factor (HIF)-2α. In this study by Painschab and colleagues (p. 26), plasma levels of four HIF-responsive proteins were measured in 20 people with excessive erythrocytosis and 20 age-matched controls. In addition the investigators looked for an association between these proteins and pulmonary artery systolic pressure. No significant correlations were found between the levels of the proteins and excessive erythrocytosis. However the levels of soluble vascular endothelial growth factor (VEGF) receptor 1 and erythropoietin were associated with an increased pulmonary artery systolic pressure.

A genetic predisposition score associates with reduced aerobic capacity in response to acute normobaric hypoxia in lowlanders

Possible associations between genetic factors and high altitude disease is a hot topic at the present time. In this study Masschelein and coworkers (p. 34) looked for a genetic basis for variations in the reduction of maximal oxygen uptake when subjects were exposed to acute normobaric hypoxia. They found that a subset of single-nucleotide polymorphisms in a series of genes had a positive association with a reduced maximal oxygen uptake.

The effects of Portulaca Oleracea on hypoxia-induced pulmonary edema in mice

Portulaca Oleracea has anti-oxidant and anti-inflammatory properties. Yue and others (p. 43) studied whether this substance reduced the pulmonary edema of mice exposed to acute hypobaric hypoxia at a simulated altitude of 7000 m. They found that there was a reduction in transvascular leakage and pro-inflammatory cytokines. However the relevance of this to high altitude pulmonary edema is not clear.

Hypobaric hypoxia induces depression-like behavior in female Sprague-Dawley rats, but not in males

There are several studies indicating that depression and suicide are higher in people who live at high altitude compared with near sea level. In this novel study, Kanekar and coworkers (p. 52) tested for depression-like behavior in rats using a forced swim test. They report that female rats displayed more depression-like behavior at simulated high altitude than at sea level, but this was not the case for male rats.

Acute normobaric hypoxia reduces body temperature in humans

It is known that many animals decrease their body temperature in response to acute exposure to hypoxia. Here DiPasquale and colleagues (p. 61) studied this response in adult humans who were exposed to air, 14%, and 12% oxygen, and found that for every 1% decrease in the arterial oxygen saturation measured by pulse oximeter, the rectal temperature decreased by 0.15°C.

Diffuse alveolar hemorrhage from systemic lupus erythematosus misdiagnosed as high altitude pulmonary edema

Usually high altitude pulmonary edema (HAPE) is not difficult to diagnose based on the patient's history, symptoms, and physical signs. However Yuliang and colleagues (p. 67) report on a 26-year-old woman who developed dyspnea and cough at an altitude of 3650 m that was initially thought to be HAPE. It transpired that she had systemic lupus erythematosus although it is interesting that this revealed itself at high altitude.

Longest survival in a crevasse

Pasquier and Cauchy (p. 71) note that a recent article described a man who survived six days in a crevasse. However they point out that in 1934, a 27-year-old man fell 20 meters into a crevasse and he survived for eight days with minimal food and clothing before he was found by rescuers.