This foundation has worked very well for physics and chemistry. We can easily define an ion's concentration as a function of pH, or a particle's position as a function of time and force. As such, we are tempted by conditioning to apply the same principles to biomedical science, such as physiology.
The focus of this note is to demonstrate that we are wrong when we try to force biological systems, systems of multiple dimensions, into the single dimension systems that give us such great comfort in physical and chemical systems.
Homeostasis is a fundamental concept in physiology. In simple terms, components of complex systems feed back into each other to keep vital variables at physiological levels. Each component of these systems has both positive and negative response elements. An M.D. intuitively looks at vital variables not only to see if they are at best levels, but to see if the components of a system are responding properly to perturbations of the system of interest.
All of this seems very rational, even obvious. The aforementioned discussion seems to be relatively intuitive for a century at least. So how can top scientists still reduce multidimensional functionality in a system down to a single largely non-relevant value? This seems to happen in the discussion of telomerase (hTERT), a gene system responsible for maintenance of the ends of chromosomal DNA. As I have discussed in a previous post detailing a system I call the Rattle Snake Hypothesis expression of telomerase is a double edge sword. On one hand, cells known as stem cells need to express telomerase as a component of the stem cells ability to continue producing a relatively infinite number of new cells. A good example is bone marrow where blood cells are produced. On the other hand, differentiated cells, or somatic cells ( of the body ) always seem to have telomerase repressed by being blocked epigenetically.
It has long been observed these somatic cells can only divide a limited number of times and then become senescent. This observation has been attributed to Hayflick , and as a result is known as the Hayflick Limit. The Hayflick limit is generally regarded as a cells first line of defense against cancer.
In cancer cells, the Hayflick Limit has always been defeated either by expression of telomerase or acitvity of the ALT pathway which accomplishes the same purpose.
The Hayflick limit is by no means the last line of defense against cancer. The immune system is an important next level of defense against cancer. As a conceptual model, we have introduced this level of defense as the Rattlesnake Hypothesis.
So what then is the best expression level for telomerase? The answer depends upon the physiological function of the particular cell in question. None the less, the question continually seams to come up, not only for telomerase, but for all genes, each of which has an appropriate expression level depending upon the physiological function of the particular cell.
The "it depends" answer never seems to be sufficient as an answer in science. In todays assignment, Tom Cech describes the best gene expression level for telomerase. Hey says at 1:01:46 :
It's on a knife edge, you don't want two times too much or two times to little, it has to be like Goldy Locks, it has to be just right. And so that could be, that is an issue with the people with too little.So my point is that on a large discussion of a cutting edge issue on a critical topic related to cancer, regulation of telomerase, it always has to be reduced at some point to a single dimension. This seems to be a compulsory requirement of people, not physical or biological systems.
With that point made, I would like to thank Tom Cech for placing this video online for the science education community, and for people interested in cancer research at the molecular level. Since Mr. Cech already has a Nobel Prize and a successful laboratory, I believe he will survive the accusation of "dimension reduction" by a blogger. Hopefully in the end, students will be encouraged to think in more dynamic terms about dynamic systems in equilibrium.