Entering edit mode
Larry
▴
10
@larry-57
Last seen 9.6 years ago
This is a multi-part message in MIME format.
------=_NextPart_000_0025_01C236DB.74C991A0
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
Greetings Dr. Irizarry and Dr. Gautier,
I have a question regarding the affy procedures that I am hoping you
can =
help me with. I am in the process of exploring use of affy analysis
as =
an alternative to using the Affymetrix expression values and in doing
so =
I am trying to understand the process for generating expression
values. =
Specifically, the medianpolish default procedure used by the express =
function. =20
As I understand it, in calculating expression values for multiple
chips, =
medianpolish does not treat the chips independently. It runs through
=
this process of removing row and column medians for all the chips then
=
generates an overall value for all the chips with corrections for each
=
chip. The expression value generated is then calculated from these
two =
values. Does this then mean that I should expect different results =
depending on the number of chips I am analyzing?=20
For example, I've run a subset of data through the process, using
chips =
hybridized with extract from untreated cells and cells exposed to =
various treatment. I then analyzed the cells using 2 chips, 3 chips,
4 =
chips and 5 chips (ie. untreated + 1-4 treatments), and the results I
=
obtained were different each time. Below is the values generated for
10 =
genes in for the untreated condition only.
gene 2 chips 3chips 4chips 5chips=20
untreated 203307_at 8.47863 8.42976 8.213314 8.44459=20
205793_x_at 9.063024 9.022368 8.84279 9.022368=20
209168_at 7.840245 7.743475 7.584038 7.817369=20
210260_s_at 10.42869 10.37537 10.02658 10.42127=20
210373_at 8.373434 8.366322 8.076776 8.366322=20
214692_s_at 8.729106 8.765005 8.457484 8.769177=20
215294_s_at 6.884695 6.95363 6.691277 6.849249=20
216017_s_at 8.90209 8.637539 8.472341 8.830136=20
217431_x_at 7.288174 7.246028 6.960451 7.288174=20
59437_at 7.960958 8.008521 7.547648 7.834895=20
I recognize that the values don't vary greatly, but I am concerned
that =
having a treatment that causes profound effects to expression of
certain =
genes may affect my results considerably (with respect to not having
=
had done that treatment). =20
I hope my question is clear and would very much appreciate your
comments =
on this.
Regards
Larry Heisler
Dept of Laboratory Medicine and Pathobiology
Program in Proteomics and Pathobiology
University of Toronto
Toronto, Ontario Canada
l.heisler@rogers.com
------=_NextPart_000_0025_01C236DB.74C991A0
Content-Type: text/html;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
<html><head>
<meta http-equiv="3DContent-Type" content="3D"text/html;" =="" charset="3Diso-8859-1"">
<meta content="3D"MSHTML" 6.00.2600.0"="" name="3DGENERATOR">
<style></style>
</head>
<body bgcolor="3D#ffffff">
<font face="3DArial" size="3D2">Greetings Dr. Irizarry and Dr.=20
Gautier,</font>
<font face="3DArial" size="3D2"></font>
<font face="3DArial" size="3D2">I have a question regarding the affy
=
procedures=20
that I am hoping you can help me with. I am in the process
=
of=20
exploring use of affy analysis as an alternative to using the
Affymetrix =
expression values and in doing so I am trying to understand the
process =
for=20
generating expression values. Specifically, the medianpolish default =
procedure=20
used by the express function. </font>
<font face="3DArial" size="3D2"></font>
<font face="3DArial" size="3D2">As I understand it, in calculating =
expression=20
values for multiple chips, medianpolish does not treat the
chips=20
independently. It runs through this process of removing row and column
=
medians=20
for all the chips then generates an overall value for all the chips
with =
corrections for each chip. The expression value generated
is=20
then calculated from these two values. Does this then mean
=
that I=20
should expect different results depending on the number of chips
I =
am=20
analyzing? </font>
<font face="3DArial" size="3D2"></font>
<font face="3DArial" size="3D2"> For example, I've run a subset
of =
data=20
through the process, using chips hybridized with extract from
untreated =
cells=20
and cells exposed to various treatment. I then analyzed the
cells =
using 2=20
chips, 3 chips, 4 chips and 5 chips (ie. untreated + 1-4 treatments),
=
and the=20
results I obtained were different each time. Below is the values
=
generated=20
for 10 genes in for the untreated condition only.</font>
<font face="3DArial" size="3D2"></font>
<colgroup>
<col style="3D"WIDTH:" 48pt"="" span="3D6" width="3D64">
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" width:="" 48pt;="" border-bottom:="" #c0c0c0;="" height:="" 12.75pt;="BACKGROUND-COLOR:" transparent"="20" width="3D64" height="3D17">
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" width:="" 48pt;="" border-bottom:="" #c0c0c0;="" background-color:="transparent"=20" width="3D64"><font face="3DArial" size="3D2">gene</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" width:="" 48pt;="" border-bottom:="" #c0c0c0;="" background-color:="transparent"=20" width="3D64"><font face="3DArial" size="3D2">2 chips</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" width:="" 48pt;="" border-bottom:="" #c0c0c0;="" background-color:="transparent"=20" width="3D64"><font face="3DArial" size="3D2">3chips</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" width:="" 48pt;="" border-bottom:="" #c0c0c0;="" background-color:="transparent"=20" width="3D64"><font face="3DArial" size="3D2">4chips</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" width:="" 48pt;="" border-bottom:="" #c0c0c0;="" background-color:="transparent"=20" width="3D64"><font face="3DArial" size="3D2">5chips</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" height:="" 12.75pt;="" background-color:="transparent"=20" height="3D17"><font face="3DArial" size="3D2">untreated</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"=""><font=20 face="3DArial" size="3D2">203307_at</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.4786296538910708""><font face="3DArial=20" size="3D2">8.47863</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.4297602050965708""><font face="3DArial=20" size="3D2">8.42976</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.2133144444841708""><font face="3DArial=20" size="3D2">8.213314</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.4445901712901907""><font face="3DArial=20" size="3D2">8.44459</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" height:="" 12.75pt;="" background-color:="transparent"=20" height="3D17"><font face="3DArial" size="3D2"></font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"=""><font=20 face="3DArial" size="3D2">205793_x_at</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"9.0630243266422497""><font face="3DArial=20" size="3D2">9.063024</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"9.0223678130284508""><font face="3DArial=20" size="3D2">9.022368</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.8427902051310703""><font face="3DArial=20" size="3D2">8.84279</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"9.0223678130284508""><font face="3DArial=20" size="3D2">9.022368</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" height:="" 12.75pt;="" background-color:="transparent"=20" height="3D17"><font face="3DArial" size="3D2"></font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"=""><font=20 face="3DArial" size="3D2">209168_at</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"7.8402454550732399""><font face="3DArial=20" size="3D2">7.840245</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"7.7434752994981499""><font face="3DArial=20" size="3D2">7.743475</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"7.58403803265095""><font face="3DArial=20" size="3D2">7.584038</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"7.8173686456628202""><font face="3DArial=20" size="3D2">7.817369</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" height:="" 12.75pt;="" background-color:="transparent"=20" height="3D17"><font face="3DArial" size="3D2"></font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"=""><font=20 face="3DArial" size="3D2">210260_s_at</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"10.428687620808001""><font face="3DArial=20" size="3D2">10.42869</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"10.3753653045646""><font face="3DArial=20" size="3D2">10.37537</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"10.026582192965201""><font face="3DArial=20" size="3D2">10.02658</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"10.4212654458644""><font face="3DArial=20" size="3D2">10.42127</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" height:="" 12.75pt;="" background-color:="transparent"=20" height="3D17"><font face="3DArial" size="3D2"></font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"=""><font=20 face="3DArial" size="3D2">210373_at</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.3734340419048507""><font face="3DArial=20" size="3D2">8.373434</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.3663222142458196""><font face="3DArial=20" size="3D2">8.366322</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.0767762976939306""><font face="3DArial=20" size="3D2">8.076776</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.3663222142458196""><font face="3DArial=20" size="3D2">8.366322</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" height:="" 12.75pt;="" background-color:="transparent"=20" height="3D17"><font face="3DArial" size="3D2"></font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"=""><font=20 face="3DArial" size="3D2">214692_s_at</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.7291063126486304""><font face="3DArial=20" size="3D2">8.729106</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.7650052646408199""><font face="3DArial=20" size="3D2">8.765005</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.4574843841862002""><font face="3DArial=20" size="3D2">8.457484</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.7691766634891408""><font face="3DArial=20" size="3D2">8.769177</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" height:="" 12.75pt;="" background-color:="transparent"=20" height="3D17"><font face="3DArial" size="3D2"></font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"=""><font=20 face="3DArial" size="3D2">215294_s_at</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"6.8846951379075403""><font face="3DArial=20" size="3D2">6.884695</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"6.9536303939127801""><font face="3DArial=20" size="3D2">6.95363</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"6.6912769974755602""><font face="3DArial=20" size="3D2">6.691277</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"6.8492487027644096""><font face="3DArial=20" size="3D2">6.849249</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" height:="" 12.75pt;="" background-color:="transparent"=20" height="3D17"><font face="3DArial" size="3D2"></font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"=""><font=20 face="3DArial" size="3D2">216017_s_at</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.9020900765987605""><font face="3DArial=20" size="3D2">8.90209</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.6375391095834608""><font face="3DArial=20" size="3D2">8.637539</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.4723405132201997""><font face="3DArial=20" size="3D2">8.472341</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.8301360436540595""><font face="3DArial=20" size="3D2">8.830136</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" height:="" 12.75pt;="" background-color:="transparent"=20" height="3D17"><font face="3DArial" size="3D2"></font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"=""><font=20 face="3DArial" size="3D2">217431_x_at</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"7.2881739681123001""><font face="3DArial=20" size="3D2">7.288174</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"7.2460279805281003""><font face="3DArial=20" size="3D2">7.246028</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"6.9604507213518998""><font face="3DArial=20" size="3D2">6.960451</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"7.2881739681123001""><font face="3DArial=20" size="3D2">7.288174</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" height:="" 12.75pt;="" background-color:="transparent"=20" height="3D17"><font face="3DArial" size="3D2"></font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"=""><font=20 face="3DArial" size="3D2">59437_at</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"7.96095786675121""><font face="3DArial=20" size="3D2">7.960958</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"8.0085213058109801""><font face="3DArial=20" size="3D2">8.008521</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"7.5476482311749402""><font face="3DArial=20" size="3D2">7.547648</font>
<td=20 style="3D"BORDER-RIGHT:" #c0c0c0;="" border-top:="" #c0c0c0;="" border-left:="#c0c0c0;" border-bottom:="" #c0c0c0;="" background-color:="" transparent"="20" align="3Dright" x:num="3D"7.8348951315787199""><font face="3DArial=20" size="3D2">7.834895</font>
<font face="3DArial" size="3D2"></font>
<font face="3DArial" size="3D2">I recognize that the values don't
vary =
greatly, but=20
I am concerned that having a treatment that causes profound effects
to=20
expression of certain genes may affect my results considerably =
(with=20
respect to not having had done that treatment). </font>
<font face="3DArial" size="3D2"></font>
<font face="3DArial" size="3D2"></font>
<font face="3DArial" size="3D2">I hope my question is clear and would
=
very much=20
appreciate your comments on this.</font>
<font face="3DArial" size="3D2"></font>
<font face="3DArial" size="3D2">Regards</font>
<font face="3DArial" size="3D2">Larry Heisler</font>
<font face="3DArial" size="3D2">Dept of Laboratory Medicine and=20
Pathobiology</font>
<font face="3DArial" size="3D2">Program in Proteomics and =
Pathobiology</font>
<font face="3DArial" size="3D2">University of Toronto</font>
<font face="3DArial" size="3D2">Toronto, Ontario Canada</font>
<font face="3DArial" size="3D2"><a=20 href="3D"mailto:l.heisler@rogers.com"">l.heisler@rogers.com</font>
<font face="3DArial" size="3D2"></font>
<font face="3DArial" size="3D2"></font>
</body></html>
------=_NextPart_000_0025_01C236DB.74C991A0--
