At the completion of the warm-up, participants stood quietly on the treadmill for 7 min and were instrumented with the near-infrared spectroscopy (NIRS) probe (Oxymon MKIII, Artinis, Netherlands) to assess changes in the concentrations of total haemoglobin ([DELTA][THb]), oxyhaemoglobin ([DELTA][[O.sub.2]Hb]) and deoxyhaemoglobin
([DELTA][HHb]) in cerebral tissue.
[10-12,24] Oxygenated blood (oxyhaemoglobin) and deoxygenated blood (deoxyhaemoglobin
) differ in their absorption spectra.
The new Cobra VIS models operate at visible wavelengths, leveraging the differential absorption of oxy- and deoxyhaemoglobin
at 500-600nm to provide depthresolved, localised oxygenation mapping concurrently with the acquired OCT image.
In the circulation, there are several pathways by which nitrites can also be reduced to NO including conversion by deoxyhaemoglobin
and cytochrome P450 [10, 12].
The central part contains areas of high signal on T1 and T2WI reflecting oxidised haemoglobin with darker areas on T1weighted images due to deoxyhaemoglobin
. The ring of surrounding hemosiderin appears dark on a T2-weighted image.
Interactions of Porphyromonas gingivalis with oxyhaemoglobin and deoxyhaemoglobin
. Biochem J 2002; 362:239-245.
Lack of oxygen causes the initial change to deoxyhaemoglobin
(blue), followed by the production of haemosederin (bluish-black to brown).
Changes in the concentration of oxyhaemoglobin (Hb[O.SUB.2]) and deoxyhaemoglobin
(HHb), evoked by an appropriate stimulus, are calculated using the modified Lambert-Beer law (MLBL) [2, 3].
Silver, "Interactions of Porphyromonas gingivalis with oxyhaemoglobin and deoxyhaemoglobin
," Biochemical Journal, vol.
The ferrous deoxyhaemoglobin
with its S = 2 spin state is responsible for the paramagnetic behavior of the deoxygenated erythrocytes.
The presence of deoxyhaemoglobin
in the tissue being imaged therefore perturbs the magnetic field, resulting in a signal loss as measured by T2*-weighted MR imaging.
This interference is due to the peak light absorption of PBV (638 nm (22)) and ISB (646 nm (23)) being very close to the 660 nm calibration for deoxyhaemoglobin
. Increased light absorption in this region will be interpreted by the pulse oximeter as deoxyhaemoglobin
, hence a reduced percentage of oxygen saturation will be displayed.