Re: Contributions to the historical record

["Bjorn Cedervall" <bcradsafers@hotmail.com>]

Sorry about a delayed response here.

>From: Jim Muckerheide <jmuckerheide@delphi.com>
>Subject: Re: Contributions to the historical record
>Date: Thu, 13 Apr 2000 09:07:42 -0500 (CDT)
>
> > Jim, I don't mind the references you are giving
>
>That's a great relief. Have you read them? I don't see their hisorical 
>context having a relationship to your "but" below:

I read the papers by Ehrenberg et al. (around 1961-1963) in 1975. And I have 
seen some of the works by P. Lambin and others (and we even have a few works 
together on DSB rejoining in human colorectal cell lines). The DNA is the 
same but the cellular response differs in many ways. The papers by Ehrenberg 
et al. were about mutations. I have not read the papers you mention. I only 
have a few points: First, there seems to be a strong correlation between 
cell killing and chromosomal aberrations (which in turn arise from DSBs). 
Second, that before going from observation to interpretation it may be good 
to also consider these other findings that go in the "opposite" direction. I 
just want to see a consistent theory.

There are sometimes _many_ relevance problems with cell culture experiments: 
The cells are disturbed, the atmosphere may be/is different, extracellular 
agents (biomolecules, proteins...) are missing, contact inhibition is often 
lacking or different in character, blast cells (like lymphocytes in culture) 
have by definition a disturbed p53 function (to make them divide) - usually 
a state achieved by a virus type of transformation. Many cells are 
radiolabeled in culture and there are other things that may happen.
There are also differences between species, between individuals of the same 
species, and between tissues of the same individual.

I will check out the references given (by Jim) later on. Right now I have to 
focus on 5-6 grant applications over the next weeks and then some vacation 
in Calif. (SJ/SF area).

It may be mentioned that about 75% of the published DSB data (from the PFGE 
method) have been based on the wrong mathematical function (DNA mass instead 
of DNA DSBs) - formally a violation of the chain rule for derivatives - one 
of these examples can be found in Science. Most of these DSB studies concern 
radiosensitivity aspects.

My own thoughts only,

Bjorn Cedervall   bcradsafers@hotmail.com

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