This concludes the feast of reason, and the last speaker is reminiscent of the last man to finish a marathon race.
2 hours ago the race has finished.
The winner is known.
It’s also known to the last speaker, but he’s determined to finish anyway.
I’ll try to remember that 'brevity is the soul of wit'.
Professor Szent, ladies and gentlemen.
The picturesque concept of 'zauberkugel' was introduced by Paul Ehrlich
to describe the effect of aromatics bearing trivalent arsenic on parasites.
Now we shall attempt a pharmacologic dissection of adrenal cortex.
I believe that techniques rule science; that seated at your desk you have no chance.
The maturity of any branch of science depends upon the available techniques.
Cancer research is not done very well, because the techniques have been rather clumsy.
We wanted a rapid and simple method to induce cancer in every experimental animal.
We want to do it quickly and without any work.
We decided we would devote a few months in search of one: the most potent of the polycyclic aromatic carcinogenic hydrocarbons.
Second, we would look for the most susceptible tissue of living creatures.
And third, we would combine A and B and determine the maximum amount tolerable by the animal.
I realise that the emotional tension is terrible.
So I’ll quickly tell what the answers to these questions are.
The most potent of the polycyclic aromatic hydrocarbons is 7,12-dimethylbenz(a)anthracene.
In English this is 7,12-dimethylbenzanthracene.
Let’s abbreviate this and it's 7,12-DMBA.
As you know this has a Chinese meaning, and it is this (writes sign on blackboard).
The sinologists in the audience recognise right away that this is 'dian' or fires; this is 'ba' or 8.
When you give a dose of DMBA you light 8 fires, namely you elicit 8 cancers.
How is this done?
One gives a dose to a young adult rat by mouth, 30 milligrammes dissolved in oil, by stomach tube, and cancer is underway.
The cancer starts within one hour.
And this is fine.
It’s slightly clumsy - slightly clumsy to give a feeding.
This is cancer induced by a single meal of the rat, but it’s a little clumsy.
So what one does now?
This is the 1968 model, the 1969 model is this.
One dissolves the hydrocarbon in oil.
One homogenises the oil in water.
And then one injects intravenously.
Therefore at a given instant of time, at a precisely known instant of time, the cancer has started.
And it’s known that the cancer is underway within 60 minutes.
Because if you take the most sensitive tissue and transplant it to another animal, the animal develops cancer.
Now the most sensitive tissue known in biology is mammary gland of young adult rats, and this is the most sensitive to 2 things:
polycyclic aromatic hydrocarbons and also to radiation.
This is still a fourth way that one can represent DMBA by the methods of calculi.
Now, science is people.
This is Werner Bachmann, 1901 to 1951, a creative chemist
who spent his professional life at the University of Michigan, studying one thing, namely free radicals.
He synthesised first DMBA.
We were busy and happy with the new discovery, producing cancer in every animal.
It was what you call instant cancer.
It was second do-it-yourself.
It was third cancer research without tears, since it was a 'Kinderspiel' and without statisticians, since it was 100%.
So this was quite good.
But a scientist in the lab is this.
All kinds of wonderful things go on in the laboratory that the scientist does not see.
I think that scientific man in the laboratory is rather good at devising experiments,
and not very good at observing that which is going on around him.
This is not Venus de Milo, this is a rat which 50 days ago received a massive intravenous injection of DMBA,
a large tolerable dose we call pulse dose, because at a precise second of time it is introduced into the blood.
50 days ago this animal was injected, and here one sees 4 of the 8 fires which are elicited.
And we studied this.
And the thing about cancer is to cure it, right?
We were doing that and looking at these things.
But one day we found these animals had very large adrenals, which were very hard.
And we thought, well this is great, now this is adrenal cancer.
But we made a section of the adrenal and found that the animals which had received DMBA,
the middle of the adrenal had turned into stone.
What was the incidence of that? - 100%.
And how long had it been going on?
Since the time of the pulse dose.
And it had taken us 3 months to observe this.
So we thought we better study the invariable effect,
the selective destruction, the zauberkugel of DMBA, on middle layer of adrenal cortex.
The adrenal gland from a biochemical standpoint consists of 3 layers:
the outer layer, glomerulosa; the middle layer, fasciculata/reticularis; and the inner is medulla.
Now these are all very long and hard names, and the mind is not a bottomless pit.
So we remember these things in the following way: One of the great chemists of the age, Guy Frederic Marrian.
We will give him an additional name which he does not have: a Richard.
Now he becomes Guy Frederic Richard Marrian.
Let us kill Frederic and Richard and then Guy Marrian will stay alive.
So that’s what we do.
This is adrenal cortex of the rat.
And blood enters the outer layer of glomerulosa.
And then it starts its slow decent down the chromatic graphic columns to the medulla.
Middle layer is this great area.
This is what is destroyed by DMBA.
Middle layer then consists of the chromatographic columns that carry the blood and of hormone sequatory cells.
And when you destroy either one or the other - and you can destroy either the chromatographic columns
or the hormone sequatory cells - when you destroy one or the other, then both die.
And that gives place to adrenal apoplexy.
This is a great vivid display of nature reminiscent of red lights in the dark.
The chromatographic columns are lined with sinusoidal endothelium which can phagocytise particulate matter.
This is a demonstration of the lining of the chromatographic columns.
Thorium dioxide has been injected, and it has been ingested.
And these are little mirrors which reflect the light and show that this is sinusoidal endothelium which can phagocytise particles.
Here is the effect of adrenal apoplexy.
3 days ago there was injection of DMBA.
And for 24 hours nothing happens.
And then at 30 hours the adrenal gland bleeds - here the control.
Here we see the 3 layers of adrenal.
The outer layer with the anastomosing capillaries, where aldosterone is formed.
Here is one of the chromatographic columns which is still open - the others have died.
And here is the adrenal apoplexy which is reminiscent of red lights in the dark.
Histology.
The outer layer is perfect and undamaged.
The medulla is perfect and undamaged.
Middle layer is killed by zauberkugel, namely (writes on the board).
And here on the 9th day you see adrenal medulla; and you see here the adrenal gland has turned into stone.
And this is a permanent mark.
This stone in the middle of the adrenal calcification of the necrotic tissue - this is the necrotic tissue –
these are adrenal glands from 6 rats.
Each one received a pulse dose 9 days ago.
And this stone means X days ago this animal was exposed to DMBA or one of its congeners.
Now, this susceptibility of the adrenal gland is ACTH-dependent.
It can be produced by a meal - namely 30 milligrammes of 7,12 - or by injection.
The young animal can tolerate more of it than the old animal.
The young animal at age 25 days received 30 milligrammes and at 45 days 30 milligrammes:
at 25 days no adrenal apoplexy, at 45 days 10 out of 10.
But: the hormone that it depends on is corticotrophin.
You start at 21 days in one of these animals and give corticotrophin for 4 days,
then a single feeding of the corticolytic agent, and then you have adrenal apoplexy.
So we’ve been interested in this observation which is... really it's kinderspiel to do.
All you need to know is, can you tell the difference between red and white?
- If you're colour-blind, select another experiment.
Here we have the base pairs.
This is a wonderful thing.
This is steric relationship.
This is thymine and adenine.
And one makes a little box to surround the base pairs.
In this little box fits 7,12-dimethylbenzanthracene.
It has the same steric size as the base pairs, guanine-cytosine or adenine-thymine.
So this little box is a simple way to judge steric relationships.
Here again is the Pandora box, constructed to hold the base pairs.
And in this fits well cortisol.
So here we see 3 things that fit in this box: the base pairs, the most powerful polycyclic aromatic hydrocarbons,
and the active sex hormones and corticotrophic hormones.
This is the dimethylbenzanthracene.
And Boylan found that it readily undergoes hydroxylation.
This very powerful carcinogen differs from most polycyclic aromatic hydrocarbons.
They undergo hydroxylation in the ring structure.
But 7,12 undergoes hydroxylation in the methyl groups preferentially to form 7-hydroxymethyl-12-methylbenzanthracene
or 12-hydroxymethyl-7-methylbenzanthracene or 7,12-dihydroxybenzanthracene.
Only this one is corticolytic; these do not destroy the adrenal cortex of the rat.
In this region if you want to get ahead sometimes what you do is twist the formula around.
And that’s what has been done here.
This is 7-hydroxymethyl-12-methylbenzanthracene related to cortisol, and you can see there is a considerable similarity.
This is buckled and this is flat.
This is not carcinogenic.
This is a weak carcinogen.
Without hydroxymethyl it is the strongest one that is known.
Now we know the molecular structure of the corticolytic hydrocarbon.
They are derivatives of benzanthracene.
It is obligatory that a methyl group be present at position 12.
It is also obligatory that an additional alkyl or hydroxyalkyl group be present at position 7.
This is a bifunctional effect of one of the functions,
namely that at position 12 being required to be a methyl group - with an ethyl group es geht nicht (it doesn't work).
This must be methyl.
Here you have a considerable leeway.
For example with the following groups we’ve made...
these derivatives are synthesised in our laboratory with a methyl group 7,12-DMBA.
This is corticolytic.
7-hydroxymethyl, 12-methyl (corticolytic), 7-formyl-12-methyl.
We’ll assume in the next minute that all of the groups are derivatives of 12-methylbenzanthracene:
1-hydroxyethyl, 2-hydroxyethyl, n-propyl, 1-hydroxy-n-propyl.
So the corticolytic agent which selectively destroys... massively destroys adrenal cortex
consists of derivatives of benzanthracene, 12-methylbenzanthracene with an oxygen… (end of recording).