Genetic changes in the high altitude native Tibetan population

Cynthia Beall (p. 101) contributes an editorial on the special topic of this issue which is certainly one of the most exciting developments in high altitude medicine and biology in the last 12 months. Dr. Beall has been one of the leaders in this area.

Sightings, Edited by John W. Severinghaus (p. 105)

High Altitude Web, Edited by Thomas E. Dietz (p. 107)

Clinician's Corner, Edited by Andrew Luks

Pulse oximetry at high altitude

Luks and Swenson (p. 109) discusses the value and pitfalls of measuring arterial oxygen saturation by pulse oximetry at high altitude. This has become a common practice by many people including those whose knowledge of the physiological background is limited.

Pro and Con, Edited by Erik R. Swenson

Most climbers develop subclinical interstitial pulmonary edema

Annalisa Cogo and Giuseppe Miserocchi (p. 121) takes the pro position while Erik Swenson takes the opposite tack. This is a highly controversial issue at the present time.

’ome on the range: altitude adaption, positive selection and Himalayan genomics

MacInnis and Rupert (p. 133) provide a general overview of the fascinating work done on this topic in the last 12 months.

Peopling the Tibetan Plateau: insights from archaeology

Aldenderfer (p. 141) tackles one of the most controversial issues which is whether the genomic changes in Tibetans have occurred during the last 3000 years. Proponents have argued that the split between Tibetans and Han Chinese occurred no more than 2750 years ago but the author contends that this is implausible based on studies of population biology.

Rapid recent human evolution and the accumulation of balanced genetic polymorphisms

Wills (p. 149) gives a general account of the rapidity of genetic changes in human populations. One of the reasons why the assertion of a rapid change in Tibetans is so interesting is that if it were true it would possibly be the fastest human genetic change that has been described so far.

Hypoxia: adapting to high altitude by mutating HIF-2α

Tissot van Patot and Gassmann (p. 157) discuss the physiological consequences of up-regulation of Hypoxia Inducible Factor. This is thought to be one of the most important features of the genomic changes in Tibetans.

Dexamethasone improves maximal exercise capacity of individuals susceptible to high altitude pulmonary edema at 4559 m

Siebenmann and colleagues (p. 169) note that dexamethasone improves maximum oxygen uptake in subjects who are susceptible to high altitude pulmonary edema, immediately after a climb to 4559 m. They now show that this effect extends for a longer duration, and they suggest that the result can be explained by increases in cardiac output and lung diffusion.

Hemodynamics and metabolism at low versus moderate altitudes

Cabrera de Léon and colleagues (p. 179) note that people living at moderate altitudes apparently have a lower mortality than populations near sea level. To determine the reasons for this they carried out an extensive study of over 6000 people living in the Canary Islands at four medium altitude ranges concentrating on blood cholesterol, triglycerides, glucose, and leptins. They found that people residing at moderate altitudes have a lower heart rate and lower serum concentrations of total leptin and free leptin than people living lower and suggest that this may explain in part the lower mortality of moderate altitude dwellers.