Random Thoughts: Exercise, aging, systems biology, medical systems engineering

The Wall Street Journal published an interesting and informative article today (http://online.wsj.com/article/SB10001424052748704350304574638331243027174.html?mod=WSJ_hps_MIDDLEThirdNews) extolling and explaining (to some extent), the benefits of moderate exercise on health and particularly on reducing the effects of aging. This is, of course, good news to people of my age! As a chemical engineer, there were a couple of interesting issues that generalize beyond this particular article.

First is that an obviously systemic activity (it is hard for just the cells lining your aorta to go for a walk) can be linked to specific molecular consequences, e.g., the lengthening of telomeres -- the strands of DNA at the tips of chromosomes. While I think that there is still some speculation occurring, it is good to see that science can determine the molecular processes that affect important aspects of human health. A second example in the article was reduction in sickness in people who exercise -- presumably by some enhancement of the immune system that occurs due the the elevated blood flow, respiration and physical stresses of exercise. These examples show how both Systems Biology and Molecular biology will be important in the future of human health. To these I see "systems engineering" as a field that can also make significant contributions as I will describe below. (Note that there are researchers working on this strategy right now so I am not claiming originality of these thoughts.)

The second point of interest for me was the complete lack of quantification of effects -- not just that (moderate exercise is walking for some number of minutes, some number of times per week) as compared to more vigorous exercise -- but that results are given statistically as a "X %" reduction in the chances of being stricken with a specific disease. In aggregate, I don't doubt that the statistics are superficially true (well maybe I doubt these a bit), but presenting the results this way makes it appear that the mechanisms and processes involved in both exercise and its effect on disease are stochastic with the outcome a random process with a certain probabilistic value. If I might speculate, I would think that in some cases, there is nothing random at all. A specific deterministic event has to occur for either the disease to take hold or for the prevention mechanism to be effective. Thus certain people are almost certainly going to receive the full value of preventions and others are almost certainly not. Resolving both the correctness of my assertion and producing a useful prediction tool may not occur soon, but is at the crux of what only engineers can bring to health care.

I say regularly, "it is not engineering until we provide numbers!" Well it is also not engineering until the numbers are accurate enough to be useful! Systems biology provides the start of the calculations necessary to provide deterministically-based medical advice, but systems engineering will be necessary to really make a difference to people. The models must be "tuned" to explain medical studies and a synergism developed to suggest the need for additional medical trials.

Let's take the need a bit further. Two older (than me) men who I know well have recently had major, lower abdominal, surgeries for cancers affecting different organs. Both appear to have had all of the cancerous cells removed (along with otherwise useful organs) but unfortunately both contracted post-operative infections. One has fully recovered and I trust the other will as well. However, given the danger of the surgery per-se and the life changing consequences of the operation, a question that would really deserve an answer is if the cancers would have spread and been the ultimate cause of their death at some future date? This is too much to ask right now, but we could again speculate that while there could be some randomness to this process, it would take a very specific deterministic event to occur, for the cancer to spread. Biology, transport phenomena, chemical kinetics and perhaps thermodynamics might be needed to get this ultimate answer -- but a really useful answer it would be!

In addition to the cancer question, these two men were in the X% of surgery patients who contracted post-op infections. It is recognized (and been so since the days of Joseph Lister) that an infection is caused by specific microbes getting into vulnerable tissue. Again, while there is some randomness (say, in the air flow around an open wound or the exact placement and depth of the sutures), this is also largely a deterministic process. Thus in principle the chances of infection for a specific person could be predicted, and, better yet, prevented! Note that the infection rates at medical institutions are different and are publicly available. (e.g., http://www.dhss.delaware.gov/dph/dpc/files/hai_report_2008_final.pdf)

So where does this random thought leave us?

Chemical engineers have very useful, detailed, accurate predictive models of how their chemical processes behave. Million dollar decisions are made daily on buying a tanker of oil that could be needed to "sweeten" a stream at a particular refinery. While now these have considerable fundamental basis, this was developed only through decades of research and comparison with plant performance to verify all of the subcomponents of the computer codes. The earliest models were based on only the mass and energy balances but were still useful for operation and design because of the prudential judgement of the engineers who used them.

We could see the same pathway toward developing useful human process systems models. The fundamental science, molecular, cellular and systems biology is advancing daily. Now is the perfect time for chemical engineers to get moving to make their contributions to this important enterprise!