Nature Article: Apoptosis

Dr. Sydney Shall sydney.shall at kcl.ac.uk
Tue Jan 4 12:12:09 EST 2000



"Paul S. Brookes." wrote:

> The assumption by everyone has been that what they're measuring is
> apoptosis.  What they in fact measure is cell viability by Trypan Blue
> exclusion.

I should like to make a very strong comment here, which does NOT affect
the comment by Paul Brookes, but he has provoked me.  The case is worse
than he says, because dye exclusion does NOT measure cell viability.
Dye exclusion measures membrane integrity. Sometimes this correlates
with cell viability positively, but sometimes negatively.  This means
that a cell that will become apoptotic will exclude trypan blue as will
a living cell. By contrast, a cell on the path to necrosis will not
exclude trypan blue.

This whole issue is complicated by the fact that in essence, dye
exclusion measures very indirectly the energy state of the cell.  If the
cell loses its energy state, then it cannot maintain the integrity of
the membranes, and nor can it complete apoptosis!

Enough said!



> No TUNEL staining, DNA laddering, or caspase activation.  The WT cells
> shown in Fig 2C don't look particularly apoptotic.   Thus it could be
> apoptosis, necrosis, or anything on the spectrum in between.The notion
> that "apoptosis is something to be prevented in order to prolong
> lifespan" is certainly not proven by this paper.  What they have
> neatly shown is that prevention of cell death and prolonged lifespan
> are linked, which isn't exactly a great leap of faith for anyone.By
> the way .... do MEF's have many mitochondria?PSB
>
> _________________________________________
> Dr. Paul S. Brookes.            (brookes at uab.edu)
> UAB Department of Pathology,   G004 Volker Hall
> 1670 University Blvd., Birmingham AL 35294 USA
> Tel (001) 205 934 1915     Fax (001) 205 934 1775
> http://peir.path.uab.edu/brookes
>
> The quality of e-mails can go down as well as up

Cheers,

Sydney Shall

-- Dr. Sydney Shall, Department of Molecular Medicine, King's College
School of Medicine & Dentistry, The Rayne Institute, 123 Coldharbour
Lane, LONDON, SE5 9NU, TEL: 01 71 346 3126; FAX: 01 71 733 3877, E-Mail:
sydney.shall at kcl.ac.uk
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