Tag Archives: antisense oligonucleotides.

18 at one blow said the molecular biologist

With apologies to the brothers Grimm, molecular biologists may have found a way to treat 18 genetic diseases at one blow [ Cell vol. 170 pp. 899 – 912 ’17 ]. They use adeno-associated virus (AAV) packing a modified enzyme and an RNA to remove repeat expansions from RNA.   The paper give a list of the 18, all but one of which are neurologic.  They include such horrors as Huntington’s chorea, the most common form of familial ALS, 3 forms of spinocerebellar ataxia and 6 forms of spinocerebellar atrophy.

They use Cas9 from Streptococcus Pyogenes, part of the CRISPR system (https://en.wikipedia.org/wiki/CRISPR)  bacteria use to defend themselves against viruses, with a single guide RNA.  Even more interestingly, Cas9 is an enzyme which breaks up RNA, but the Cas9 they used is catalytically dead.  They think that just binding to the aggregated RNA containing the repeats is enough to break up the aggregate.  This is the way antiSense oligoNucleotides are thought to work.

The problem with getting a bacterial enzyme into a human cell is avoided here by using a virus to infect them (AAV).  It did get rid of RNA aggregates in patients’ cells from 4 of the diseases (two myotonic dystrophies, and the familial ALS).

It is almost too fantastic to be true.

Why almost all of these repeat expansion diseases affect the nervous system is anyone’s guess.  As you can image theories abound.  So all we have to do is figure out how to get the therapy into the brain (hardly a small task).

Back from the 50th Med School Reunion

Mostly some social notes from my 50th Med School reunion (Penn), but first some serious science.

I did two years of graduate work in chemistry between college and med school, and one of the guys I taught organic to is an academic research neurologist. He told me that they had some encouraging results using antisense oligonucleotides to remove the excessive repeat CTGs from myotonin, the gene defective in myotonic dystrophy. They were able to get it into cells, and even showed some clinical benefit in animal models. So he’s still using chemistry.

Myotonic dystrophy is one of the few triplet expansion diseases that makes sense to me, because unlike most of them, it affects a wide variety of tissues, not just the nervous system.

Just about everyone had a great time at the reunion. On entering med school I was told, that I’d know my classmates better than my spouse. Well, I certainly spent more time with them in the clinical years.

It was a happy time and yet sad as well, as we all knew that this was probably the last time we’d all see each other.

The previous post https://luysii.wordpress.com/2016/05/11/off-to-the-50th/ had a lot about (the lack of) minority representation back then.

Things have improved, as there is now an office of diversity (so Penn is now doing more than paying hypocritical lip service to it — vide Elizabeth Warren).

Our Nigerian classmate came back. He’d spent 17 years back home in Africa but left because he was unable to fight the corruption there, even as a native son. He hassled a black medical student from Africa, finding that she was of the Yoruba tribe, telling her to go back and serve her country (at least for a while).
So things have improved, but not enough. An an affair Friday night, all 5 or so of the blacks present were sitting at the same table. I barged in saying I was bringing some diversity to their table, and initially got some strange looks. But then I told them a few of the events of the previous post and they warmed up. At least the country is  now getting the benefit of their brains.

We’ll know things have really improved, when black physicians feel comfortable enough to mingle with the crowd.

About 65 of the 125 of us were back. Only 18 people were listed as having died, which seems like a very small number for a group of 125 26 year olds 50 years later. I do know of one unreported death of a classmate from AIDS.

This is actually nothing new — and here are my notes on a study done nearly 30 years ago. My speculation is that, docs get a lot of reinforcement, seeing the effects of negative health choices. I doubt that all of it is due to social or economic class, although some must be.

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[ J. Am. Med. Assoc. vol. 259 p. 3158 ’88 ] This is an overview of the Physicians’ Health study in which 22,000 American physicians took either aspirin or placebo in a double blind study. They were only taking 5 grains of aspirin every other day. Cardiovascular mortality was cut, but overall mortality was not. However the group experienced just 88 deaths when 733 would have been expected. . This may be due to a beneficial life style, or social class. Thus the EIGHTFOLD lower mortality throughout makes the study harder to interpret. Amazingly, the authors of the study don’t really focus on why the study group (even those on placebo) did so well, but whether the aspirin added anything extra. What we need is to reduce mortality in our patients eightfold and then worry about giving aspirin.

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Here is a tale of the bad old days for the feminists among you. There were under 10 women in our class of 125. One very bright woman wanted to be a surgeon. She asked Dr. Everett Koop about it. This was when Koop was basically inventing the specialty of pediatric surgery at Children’s Hospital of Philadelphia (CHOP), and long before he became Surgeon General.

He gave her some very hard and very honest advice (this was Koop after all). He told her that the first rate surgery residencies simply were not accepting women. To rise to the true level of her ability, she’d need to choose something else. She didn’t like this one bit, but did follow his advice, went into another field and became department chair at another Ivy League med school.

Lastly two stories about the All American basketball player in our Class (Jerry Gardner Kansas ’62). He’s about 6′ 2″ now, and using a cane as he’d had hip surgery a few months ago. He did note that back then Freshman weren’t allowed to play, so he still has a year of eligibility left. Jerry went to NIH after graduation and established a lab studying GI hormones.

Further proving that time does not heal all wounds, Jerry reminisced about the two foul shots he missed at the tail end of a game in the NCAA final (or semifinal) which might have won them the game. For further examples of the phenomenon see — https://luysii.wordpress.com/2010/10/25/time-does-not-heal-all-wounds/