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236 Kohlmann et al.<br />

symbol, and cytogenetic bands. The static information for each probe set details<br />

the probe sequences, accession numbers, and textual description, and describes<br />

what the probes were designed to interrogate. The static probe set data<br />

are also depicted graphically.<br />

3.4.7. Software<br />

Software packages from Affymetrix (www.affymetrix.com/support/) are<br />

used for principal data acquisition (MAS5), storage (MicroDB), and analysis<br />

(DMT). Individual gene expression profiles can also be prepared as Microsoft<br />

Excel tables.<br />

The following packages can be applied for identification of differentially<br />

expressed genes and classification:<br />

SAM (Stanford University; www-stat.stanford.edu/~tibs/SAM/index.html)<br />

Bioconductor (open source; www.bioconductor.org)<br />

q-value (University of Washington; faculty.washington.edu/~jstorey/qvalue/)<br />

LIBSVM (National Taiwan University; www.scie.ntu.edu.tw/~cjiln/libsvm/).<br />

SAM is available as a Microsoft Excel Add-in. Bioconductor is an open<br />

source and open development software project for the analysis and comprehension<br />

of genomic data (22). Bioconductor packages provide statistical and<br />

graphical methodologies for analyzing genomic data. LIBSVM (Version 2.6)<br />

is a software solution for SVM-based classification. The q-value software takes<br />

a list of p-values resultling from the simultaneous testing of many hypotheses<br />

and estimates their q-values (13). In addition, further third-party software packages<br />

can be used for statistical analyses and data visualization:<br />

SPSS (SPSS Inc.; www.spss.com/)<br />

Pathways Analysis (Ingenuity Systems; www. Ingenuity.com)<br />

GeneMaths (Applied Maths, Inc.; www.applied-maths.com)<br />

J-Express (MolMine AS; www. molmine.com/).www.applied-maths.com<br />

4. Notes<br />

1. The whole sample target preparation procedure can be performed in two working<br />

days, taking the assay’s safe stopping points into account. Day 1 includes isolation<br />

of total RNA, synthesis of ds cDNA, cleanup of ds cDNA, and ethanol precipitation<br />

overnight. The IVT reaction, cRNA cleanup, quantification, and<br />

fragmentation are performed on day 2. After a hybridization cocktail has been<br />

prepared, it is either subsequently hybridized to a probe array, or can be stored at<br />

–20°C for later use. Throughout all steps, powder-free gloves should be worn.<br />

All steps to minimize the introduction of exogenous nucleases should be taken.<br />

Water used in the protocols has to be molecular-biology grade. All steps should<br />

be performed in nuclease-free 1.5-mL reaction tubes.

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