RE: radon - DNA damage - yeast - input from the biologists

["Jim Muckerheide" <jmuckerheide@cnts.wpi.edu>]

Bjorn, Cancer doesn't "start from a cell" as in the statement: "cancer

is a problem of cell society" in clarifying this problem in the nature

of carcinogenesis in the biology and medicine community. Mitchel and

Kondo seemed to make that clear. You are right in radiation

damage/response context, but that doesn't address the biological

responses of the tissue, organ, or organism, nor of the mechanisms that

provide for enhanced immune response, enzymatic repair, and expression

of proteins and genes, cell cycle delay, etc. When low dose radiation

REDUCES cancer incidence, you may still find increases in chromosome

aberrations and DNA damage in the tumors that do exist! :-) The

biophysics of DNA damage is NOT the biology of whole organisms

considered by the biologists. (Note also that the infamous 'bystander

effect' is intrinsic to stumulatory responses from very low doses

hitting very few cells. The misrepresentation of the relationship

between "response" in non-hit cells and that "rad damage is more than we

thought and increase rad risks" is used to get the media to fear-monger

about radiation by those committed to support the LNT / rad protection

costs/funds that make the "science" disingenuous.)

 

Regards, Jim

========



	-----Original Message----- 

	From: Bjorn Cedervall 

	Sent: Wed 16-Jan-02 12:50 PM 

	To: radsafe@list.vanderbilt.edu 

	Cc: 

	Subject: RE: radon - DNA damage - yeast - input from the

biologists

	

	



	>irrelevant chromosome aberrations, which can indeed be

'markers' of

	radiation exposure, but are of no real significance to health

effects

	since the issue of producing cancer is DNA repair/mis-repair,

not the

	dead ends of permanently damaged chromosomes :-)

	---------

	I cannot agree with this - the cancer cells start somewhere.

Those which do

	not die due apoptosis and other phenomena undergo a successively

increasing

	amount of lost alleles, point mutations, DNA frameshifts, and

messed up

	karyotypes (disturbed spindle functions) - often it begins with

a

	duplication of all chromosomes (to make them tetraploid) - then

followed by

	some lost chromosomes resulting in hypotetraploid cells.

	

	To make this more clear: Most cells can remain functional in

many respects

	while they are having translocations etc. The critical events

may occur when

	you get breakpoints in promotor regions of DNA or destroy the

function of

	genes regulating the cell cycle, the integrity of DNA (repair

and structure)

	or signaling systems (from membrane level to the nucleus and

promotors).

	

	Specific translocations are wellknown for the Philadelphia

chromosome,

	Burkitt's lymphoma (G. Klein et al.) and other contexts. For a

lost Rb

	function - see the papers by Nordenskiold et al. (Karolinska

Institutet). In

	addition, you should study DNA rearrangements in tumors as they

have been

	described in leading journals like Cancer Research.

	

	I don't know if you mean to imply something about biologists or

	technologists (good or bad?) - I belong to both categories. The

findings

	(messed up DNA in tumor cells) are all there - lots of them - if

it is a

	math person or biologist who points at them should be quite

irrelevant.

	

	Bjorn Cedervall    bcradsafers@hotmail.com

	http://www.geocities.com/bjorn_cedervall/

	

	

	

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