Wednesday, June 30, 2010

Pneumococcal capsule,Hyaluronan,Penicillin like electron, proton and neutron to Dawson

I have said that Martin Henry Dawson's roughly 20 year career as a medical scientist can be divided into three parts based on three types of streptococcus bacteria: s pneumococcus, s pyogenes and s viridans.

Another way to look at the three phases is to look at the key substance he was studying in each phase and contrast how our body felt about each of them.

The pneumococcus flourish in the blood stream and in our liquid-oriented parts of our body by wearing a sugar-coated capsule around themselves, to evade the non-adaptive part of our immune system.

But humans also have an adaptive immune system and it can learn to recognize the sugar capsule and kill the bacteria inside it.

To survive, the pneumococcus have learned, in their own counter defense, to make a 100 different capsules (or to wear no capsule at all !). When this in turn doesn't work, they trade the various capsules around by HGT - horizontal gene transfer - the only reason we humans could begin play around with DNA.

So Dawson's pioneering work on DNA is obviously still hot stuff.

In terms of the body's immune system, these sugar capsules are highly anti-genic : the body sees them as the enemy and goes into warp overdrive to deal with them.

Dawson then flipped 180 degrees and dealt with the capsule of the deadly GAS bacteria - a bug that can still kill humans in dozens of different ways.

Their trick is to have a capsule made out of something only animals make - this chemical hyaluronan is used all through the animal body in dozens of quite different applications.

We humans now use it ,in medicine, for dozens of additional uses.

Our body regards it as 100% gen, ie  "us" - the very us-ness of us.

Sometimes however the body in attacking the bacteria inside the hyaluronan capsule, thinks the capsule is also somehow non-human and then goes off attacking parts of the human body that look just like it.

This is called 'molecular mimicry' and it lies behind auto immune diseases like Rheumatic Fever that Dawson works so hard to cure.

Because so many of the diseases we are likely to get today are considered to be auto immune diseases, this also remains hot stuff in the area of medicine and science.

Finally Dawson flipped yet again ,180 degrees ,to take up the cause of penicillin in 1940 when it interested no one.

It is, at best, an okay killer of bacteria - when just viewed in its killing aspects. From the viewpoint of working doctors or pharma executives in 1940, its killing disadvantages far outweighed its moderate killing abilities.

Dawson saw beyond this, to grasp the one thing about penicillin which remains unique about it even today when there have been thousands and thousands of antibiotics tested
for their usefulness in fighting disease.

Some individuals are allergic to penicillin - very very few seriously.

But broadly speaking only some of us are allergic to something , while if it is toxic, it is toxic to all of us.

Penicillin isn't toxic to us - at all . The salt it is wrapped around, chemically speaking, can be toxic if we don't watch our fluid levels, but that is about it.

Our body regards this small molecule as basically invisible - it does not regard it as gen ( part of itself) or antigen (part of a pathogen) nor  even as a potential food - it passes quickly through our body, our liver above all, as invisible and as harmless as water.

Most doctors - Alexander Fleming above all - only saw the fact that penicillin passed quickly through the body as its prime disadvantage.

But Dawson had devoted just 15 years to substances that hung about the body only too well and his mind was 'prepared'  (in the Pasteurique sense of that word) to see the advantages of any substance that our body regarded as neither genic or antigenic or as food.

Penicillin was the neutron of the human immune system and Dawson put that neutron to work......


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