Each oligonucleotide microarray (Affymetrix HG_U133A) contained 22.218 human probesets and in our experiments discovered between 48.1% and 53.7% "present calls" as calculated by the statistical detection algorithm of Affymetrix.
In all cases, fold-change correlation and consistency index improved when only probe sets called as "Present" in 80% or more samples in a group were considered.
For the transcripts, with different probe sets called as "present", we selected the most in 3' UTR of the gene and taking into account the probe set repetitions.
Only probe sets called as "present" on all arrays (n = 18) were further analyzed (110,026 probe sets) by one-way ANOVA and filtered by p value (p ≤0.05) (corresponding to 4,384 probe sets that respond to light).
This increase in detection sensitivity appears to be a reflection of higher signal intensity and lower signal to noise ratio as evidenced by the transformation of an absent call to a present call as shown in Table.
We identified 5 MMPs (MMP-3, MMP-8, MMP-9, MMP-13 and MMP-14), 3 TIMPs (TIMP-1, TIMP-2 and TIMP-3), 11 cathepsins (cathepsins B, C, D, E, F, G, H, K, L, S and Z) and 3 cystatins (cystatins B, F and C) that were highly expressed at the mRNA level in murine joints during AIA and resulted in a present call as a detection signal analyzed by MAS 5.0 (Table 2).
Chronic toxicity tests (both with males and females) and reproductive tests with pregnant females and then with the developing progeny over several generations (none of these steps exist at present) are called as a whole the Toxotest approach (or Risk management test, see "Details on the new suggested Toxotest approach").
One of the most interesting parameters for investigators is probably the percent present calls, defined as the fraction of "expressed" probe sets relative to the total of the array.
The version of structured analysis presented is called as "postmodern" because it combines design approaches from several schools, some of which oppose one another, namely Yourdon-style structured analysis, Jackson System Development, and object-oriented analysis.
We considered a gene detectable if the mean expression in any sample was greater than 50 signal units and the percentage of samples with a Present (P) call as determined by GCOS default settings was greater than or equal to 66%.
