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Sample A: Cover Page of Thesis, Project, or Dissertation Proposal

Sample A: Cover Page of Thesis, Project, or Dissertation Proposal

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Discussion<br />

In this chapter we have presented latent structure associated with the genes in our candidate<br />

ProbeSet list when BaFL-provided values are used, based upon c<strong>or</strong>relation <strong>of</strong> the disease samples<br />

(Figures 4.1-3). This is the reverse <strong>of</strong> the n<strong>or</strong>mal strategy, in which an analyst uses gene<br />

c<strong>or</strong>relations to expl<strong>or</strong>e the structure between samples. There is an improvement in the<br />

Bhattacharjee data model when the BaFL pipeline is implemented to supply the Probeset values<br />

as compared to the RMA and dCHIP methods.<br />

The impact <strong>of</strong> osteopontin expression levels (Figure 4.4-7) is a well known feature in the<br />

progression <strong>of</strong> lung cancer, as is the difference among lung cancer sub-types [19, 20, 22, 23].<br />

However, a novel result <strong>of</strong> the analysis is the demonstration that the significance <strong>of</strong> the<br />

expression levels is not stage specific (Figures 4.6-7), but rather pathology specific, f<strong>or</strong> BaFL-<br />

supplied values. This change in perspective suggests why our data fails to demonstrate the same<br />

survival rates as the Donati study which suggested long term survival <strong>of</strong> stage I patients with<br />

elevated levels <strong>of</strong> opsteopontin [20]. An attempt to contact this group to obtain supplementary<br />

data in <strong>or</strong>der to determine whether their stage I sub-population had a significant prop<strong>or</strong>tion <strong>of</strong> low<br />

grade tum<strong>or</strong> patients has been unsuccessful. Osteopontin is under development as a potential<br />

biomarker, and eff<strong>or</strong>ts have been made to improve the perf<strong>or</strong>mance <strong>of</strong> the biomarker by coupling<br />

it with other biomarker results [ref]. Our results suggest that an additional element leading to<br />

success would be to inc<strong>or</strong>p<strong>or</strong>ate the tum<strong>or</strong> grade clinical data into the test.<br />

In earlier chapters the multiple-test problem was ign<strong>or</strong>ed (leading to the candidate list <strong>of</strong> 325<br />

ProbeSets described above). The Bonferroni c<strong>or</strong>rection was implemented f<strong>or</strong> its low tolerance f<strong>or</strong><br />

108

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