Since the earliest days of the non-invasive technique of in vivo near infra-red spectroscopy (ivNIRS) there has been the potential to monitor the redox state of the important respiratory chain enzyme cytochrome aa3. This has particular relevance to hypoxic-ischaemic insults to brain cells, such as may occur in the fetus during birth, in newborns with unstable cerebral autoregulation, or in adults with many forms of brain injury. However, although the feasibility of monitoring cytaa3 with ivNIRS has been largely proven there is currently no apparent interest in applying the method clinically. This might be a matter of a lack of knowledge in how to use the data collected, or it might well be that equipment is too expensive, or cumbersome or unreliable. Do any clinicians have a view on the clinical value of this method? Do any engineers feel that more needs to be done in refining the technology?
My answer is one of your guesses, namely, the equipment is too expensive, cumbersome, and unreliable. This is because the signals of cytochrome aa3 measured by NIRS is much smaller than those of hemoglobin. In order to obtain accurate signals of cytochrome aa3, the system needs to measure a band of spectrum as
well as to go through an enough penetration depth. Also, one focus in NIRS is to form brain images, so much attention is paid to algorithm development for image reconstruction, rather than to quantifying cytochrome aa3.
I think this is a good question for us who are researchers in the NIRS field. Here is a paper you could read to learn more if you wish:
"Cytochrome c oxidase response to changes in cerebral oxygen delivery in the adult brain shows higher brain-specificity than haemoglobin," by
Christina Kolyva, Arnab Ghosh, Ilias Tachtsidis, David Highton, Chris E. Cooper,
Martin Smith, Clare E. Elwell
NeuroImage, Volume 85, Part 1, 15 January 2014, Pages 234–244
This paper is an open article, so you can download it for free.
Thank you Hanli for your answer. The lack of a lot of answers for this question suggests that not many people know of the NIRS detection of cyt aa3 redox state. The reference you give is very useful and I know of the work quite well, thanks.
NIRS instruments now seem to focus just on tissue oxygenation index which is rather like oxygen saturation,m so the instruments can be very low cost and easier to use. Perhaps later some people will look at cyt aa3 again.
Thanks, Peter, for your feedback. I think this kind of communication is useful.
I would surely hope that NIRS can measure Cyt aa3, but it seems that it is very difficult to do so. Also, some colleagues with bio-chem knowledge are needed. I guess I will keep this desire in my mind and hope I will come across the opportunity.
- Badges
- Science topic