Facilities and Technologies
Hypobaric Chamber
The hypobaric chamber is the centerpiece of ARC’s laboratory. It simulates altitudes from Denver (5,280 feet) to beyond the summit of Mount Everest. An airlock provides access for personnel and equipment without disturbing the atmosphere of the main chamber room. The pressure control is accurate to 0.5%. This enables extremely precise control of the altitude within the chamber.
Near Infrared Spectroscopy Near infrared spectroscopy (NIRS) allows for the assessment of oxygen levels within specific tissues. Light in the near infrared spectrum is absorbed differentially by oxygenated and deoxygenated hemoglobin. By shining this light into a tissue and measuring the amount that emerges, oxygen levels and blood volume within the tissue can be quantified. NIRS has several advantages over other similar techniques. It is portable, it can be used during exercise, and it has a fast sampling rate that allows for study of oxygenation changes with each heart beat.
The lab primarily uses NIRS to study how exercise and altitude impact oxygenation within particular regions of the brain. .
Transcranial Doppler Transcranial Doppler ultrasound (TCD) is used to study brain blood flow noninvasively. It works in much the same way as a radar gun. High pitched sound waves are directed toward specific blood vessels within the brain where they are deflected by bone, blood, and other brain structures. The change in the frequency of waves that return to the probe is used to calculate blood flow velocity.
Since changes in brain blood flow are related to altitude sickness, TCD is extensively used to unravel the mechanisms of acute mountain sickness.
RespirAct A major challenge when studying responses to altitude is separating the influences of oxygen and carbon dioxide. Because the concentrations of these gases are tightly coupled, it is impossible to determine if a physiological effect is the consequence of changes in oxygen, carbon dioxide, or some combination of the two. Manually creating gas mixtures that hold either oxygen or carbon dioxide constant while changing the other is time consuming and imprecise. The RespirAct represents a major innovation in the control of ventilatory gases. It enables investigators to independently manipulate oxygen and carbon dioxide values with a precision of 1 mmHg.
Microarray As science has progressed, the emphasis has shifted from the level of the organism to that of the cell and the molecule. It is now possible to study not only which version of specific genes a person possesses but also which genes are turned on at any particular moment. This allows investigators to quickly determine which genes among tens of thousands are linked to specific diseases or responses, such as altitude illness. Microarrays are particularly useful in identifying genetic targets for future studies and for differentiating groups on a fundamental level.
Magnetic Resonance Imaging ARC researchers make active use of the 3 tesla MRI scanner at the Brain Imaging Center in an adjacent suite. The magnet, dedicated for research-use only, is equipped with high performance gradient coils (maximum gradient amplitude of 43 mT/m and maximum slew rate of 150 T/m/s), a head volume RF coil, an 8-channel phased-array head coil, and a whole body RF coil. The system is also equipped with a BrainWave package for real-time fMRI exams using a gradient-echo echo-planar imaging (EPI) pulse sequence. The system has been recently upgraded with the capability of acquiring MR data using 8 channels simultaneously.

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