Altitude

The possible effects of blue light during acute hypoxia and the circadian rhythm on several physiological and cognitive parameters were studied. Fifty-seven volunteers were randomly assigned to 2 groups: nocturnal (2200-0230 hours) or diurnal (0900-1330 hours) and exposed to acute hypoxia (4000 m simulated altitude) in a hypobaric chamber. The participants were illuminated by blue LEDs or common artificial light on 2 different days. During each session, arterial oxygen saturation (Spo2), blood pressure, heart rate variability, and cognitive parameters were measured at sea level, after reaching the simulated altitude of 4000 m, and after 3 hours at this altitude. The circadian rhythm caused significant differences in blood pressure and heart rate variability. A 4% to 9% decrease in waking nocturnal Spo2 under acute hypoxia was observed. Acute hypoxia also induced a significant reduction (4%-8%) in systolic pressure, slightly more marked (up to 13%) under blue lighting. Women had significantly increased systolic (4%) and diastolic (12%) pressures under acute hypoxia at night compared with daytime pressure; this was not observed in men. Some tendencies toward better cognitive performance (d2 attention test) were seen under blue illumination, although when considered together with physiological parameters and reaction time, there was no conclusive favorable effect of blue light on cognitive fatigue suppression after 3 hours of acute hypobaric hypoxia. It remains to be seen whether longer exposure to blue light under hypobaric hypoxic conditions would induce favorable effects against fatigue.

ACUTE MOUNTAIN SICKNESS (AMS) is a syndrome encoun- tered by travelers to high altitude who ascend too high too fast (7, 19). Symptoms include headache, nausea, malaise, dizziness, and difficulty sleeping. AMS has been well described for several hundred years, but the pathophysiology is unresolved. Surprisingly, the role of exercise in the pathogenesis of AMS has not been systematically studied. Our personal observations, an- ecdotal reports by others (5, 13, 16), and one prelimi- nary study (4) suggest that overexertion, independent of prior physical condition (11), may be related to the development of AMS. This notion is supported by the finding that the incidence of AMS is lower when subjects passively ascend to high altitude (as in an altitude chamber or by helicopter ascent on mountains) or actively ascend, but slowly (7), compared with active and rapid ascent (14). However, because passive trans- port to high altitude can occur within minutes, and climbing to the same altitude...

Polychlorobiphenyls (PCBs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and DDT were examined in the muscle of brown trout (Salmo trutta) from a high mountain lake located in the Pyrenees (Catalonia, Spain) that was used as a model of these lacustrine environments. Results indicate that fish age is the main factor of variability among specimens in this population that is subjected to atmospheric inputs of the organochlorine compounds (OC). Increases of 2- and 20-fold between fish aged 1 year and 15 years old are found. The observed pattern cannot be explained in terms of fish size, condition factor, or muscle lipid content. Higher molecular weight compounds (higher lipophilicity) are better correlated with fish age than low molecular weight compounds. A transformation from 4,4′-DDT to 4,4′-DDE occurs in fish after ingestion; this results in amplified age-dependent signals, especially in male specimens. In contrast, PCB congener #180 has lower age dependence than the general OC group, which could be due to its high hydrophobicity (log Kow > 7). In any case, selective accumulation of hydrophobic compounds is already observed among younger fish (age, 1 year). Due to this effect, the relative OC composition does not reflect the main OC pollutants in the lake waters.

Upon ascending above 2500 meters sea level, the human body undergoes a series of physiological changes that have been studied during years. These changes undertake various systems including gastrointestinal tract, with diverse clinical manifestations, most mild and therefore little reported and are underdiagnosed. Two pediatric patients who atended to the Pediatric Unit of Gastroenterolog, Hepatolog and Nutrition (Gastronutriped) in Bogota, in whose we documented symptoms affecting gastrointestinal tract associated with high altitude.Regarding to these cases, a review of the available literature focusing on physiolog, clinical manifestations and feasible treatment was made. The final aim of this article is to sensitize to health care professionals working in cities located at high altitudes, to consider this entity as a differential diagnosis in children from places with lower altitude.