genotype-dependent (87.7% of DD, 94.9% of ID and 100% of II individuals p=0.04); I allele
frequency for those reaching the summit was 0.47 compared to 0.21 for those who did not
(p=0.01). The onset of AMS on Day 1 appeared to be dependent on genotype (p=0.003), but with
those heterozygous were less affected and they had only a borderline association with AMS
severity (p=0.045) ACE genotype was not associated either with AMS onset or severity on Day 2.
In conclusion, we have shown that success in reaching the summit of Mont Blanc is influenced by
ACE I/D genotype, but this does not appear to be due to an effect on the onset or severity of
AMS. First author's emails for correspondence agiosgeorgios@hotmail.com
giorgos.tsianos@bio.gla.ac.uk
228.
IMPORTANCE OF NUTRITIONAL STATUS AND REGULATED BREATHING IN
METABOLIC ADAPTATION TO HIGH ALTITUDE. Thuppil Venkatesh
1
, C Vidyasagar
1
.
Department of Biochemistry & Biophysics St. John National Academy of Health Sciences,
Bangalore IND
1
.
Increasing population representing varies genetic background are exposed to high altitude
condition. Genetics seems to play a prominent role in environmental adaptation to high altitude.
Biochemical metabolic regulation at molecular level is found to vary with genetic origin.
Amongst two of the most vulnerable environmental changes to which people are exposed are with
reference to temperature and oxygen. At high altitude both cold and hypoxia coexist. Hypoxic
and hypothermic stress seems to operate independently or in tandem which is well documented.
Hough human performance in hypoxic and hypothermic conditions depends upon many factors,
amongst them duration and intensity of hypoxia, exercise, rest and nutritional status are having a
significant effect. Altered biochemical pathways during acclimatization for energy production
and conservation are also well established. Hormonally regulated arterial oxygen saturation
during the process of acclimatization is reflected with the changes in the levels of hormones in
serum. Limited to oxygen supply to the brain the entire endocrine regulation by the master gland
is also affected during the process of acclimatization. Adequate ideal nutritional status and
regulated breathing are considered to have a role in the process of acclimatization process.
Significant differences during the process of acclimatization in low and high lenders, persons
practicing regulated breathing and animals with good olfactory capacity are noticed. Studies by
the authors on both low and high lenders have indicated the biochemical basis of cold injuries
such as frost bite and hypothermic shock. Role of cryoglobulins on the onset of frost bite and the
significant involvement of antioxidants have opened new windows towards the understanding of
the nutrition and metabolism. Altered blood flow to the brain tissue under hypobaric hypoxia in
contrast to the normobaric hypoxia is differentiated at biochemical and molecular level.
Biochemical and nutritional basis of acclimatization, adaptations and short term physiological
adjustments seems to be significant in minimizing AMS in low lenders exposed to high altitude
conditions. In this regard some of the age old practices with regard to nutrition provide an insight
to the existing problems faced by low lenders looking for academic or recreational activities at
high altitude conditions.
229.
CIRCADIAN VARIATION IN TESTOSTERONE AMONG BOLIVIAN MEN INDIGENOUS
TO HIGH ALTITUDE. Virginia J. Vitzthum
1
, Carol Worthman
2
. Indiana University,
Bloomington, IN, USA
1
, Emory University, Atlanta, GA, USA
2
.
In humans and model animals, controlled exposure to hypoxic conditions disrupts normal
circadian rhythms in thermogenesis and respiration. Analogous responses in high altitude (HA)
residents may contribute to sleep disturbances. In clinical studies at low altitude (LA), sleep
fragmentation and hypoxia appear to modify nocturnal testosterone (T) levels. We tested the
hypothesis that circadian variation in T among free-living men indigenous to HA differs from that
of LA men (who typically exhibit a diurnal decrease where TPM ~ _TAM). AM and PM salivary
samples were collected every other day over 5 days from 65 men (n = 195 AM-PM pairs; mean
age = 33 years), resident in the rural Bolivian altiplano (4000 m). A negative diurnal change (D-)
