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Commercial Response

The recent discussions about selecting MP or Confocal for a core imaging
facility have addressed many of the important issues but introduced some
misunderstandings as well.

At Bio-Rad we have always highlighted 3 principal strengths of MP - 1)
Deeper imaging  2) More flexible access to UV probes and autofluorescence
and 3) Extended time study of live cells and tissue.  All of these
advantages have now been demonstrated and you can see some excellent
examples in the image gallery on our WEB site

www.cellscience.bio-rad.com/gallery2.htm

As with any technique it is important that the experiment be well
designed. We emphasize 2 golden rules when MP imaging - 1) Use the lowest
laser power possible and  2) Use the longest wavelength excitation
possible.

There is extensive literature on the biological effects of MP imaging.
General experience shows that toxicity effects increase rapidly above a
certain 'dose' threshold and that toxicity is more severe for shorter
wavelength illuminations than for long.  Many of the problems experienced
in the early days of MP imaging were due to the use of excessive laser
power combined with the use of inappropriate illumination wavelengths.  In
modern systems such as the Radiance2100TM MP these problems are substantially overcome by a) reduction of the
illumination dose, which is made possible by higher sensitivity 'direct
detection' systems and b) improvements in microscope optics for use at
near IR wavelengths.

Bleaching in MP imaging is still not well understood but the same golden
rules and best practices apply if bleaching effects are to be minimized.

If all these precautions are taken then extreme sample damage will only
occur if the sample strongly absorbs at IR wavelengths. Most samples are
transparent to the IR wavelengths of MP but there will always be a few
good stories to tell about samples suffering catastrophic damage.  All one
can say is that these experiences prove that IR absorbers....absorb IR!

Returning to the question about whether one is better off setting up a
core facility with a fully specified, combined confocal/MP system or a
simpler MP-dedicated system, there has always been a tendency for the
stakeholders to ask for every possible option.  Manufacturers have gone to
great lengths to deliver this capability but in truth a simpler system
will have fewer design compromises. We are now beginning to see users who
purchased a combined confocal/MP system for their first exploration into
MP imaging follow up with the purchase of a MP-dedicated system for those
applications for which MP is the proven preferred approach.

Where next?  As the pioneer in development of commercial MP systems
Bio-Rad is obviously pleased that the technique is becoming well accepted.
It is especially interesting to see how much of the research with MP
involves tissue imaging for applications that are at the interface of
research and medical treatment.  Some good examples can be found on the
following web sites: -

http://www.drbio.cornell.edu/MPE/mpe.html
http://www.aecom.yu.edu/aif/intravital_imaging/introduction.htm
http://www.med.harvard.edu/publications/Focus/2001/Mar9_2001/neurology.html
http://www.graylab.ac.uk/groups/advtec/home.html

At Bio-Rad we are enthusiastic about the applications of MP imaging but
are equally enthusiastic about confocal imaging.  We will do all we can to
help users make the right choice for their application.


Bio-Rad Cell Science Division