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Role of Intestinal Microbiota in Ulcerative Colitis

Role of Intestinal Microbiota in Ulcerative Colitis

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samples for all primer sets. Analysis <strong>of</strong> the standard curves allowed verification <strong>of</strong> PCR efficiency<br />

for the chosen PCR conditions. Additionally, all primers were tested to confirm sensitivity and<br />

specificity us<strong>in</strong>g DNA from pure bacterial species.<br />

Statistical analysis<br />

Statistical analysis <strong>of</strong> the qPCR data was performed with SAS JMP s<strong>of</strong>tware (version 6.0.2; SAS<br />

Institute Inc., Cary, North Carol<strong>in</strong>a, USA). Data was analyzed by a mixed model ANOVA, where<br />

microbiota source (healthy, UC patients <strong>in</strong> remission and UC patients <strong>in</strong> relapse) and community<br />

(lumen and mucus) were used as fixed effects, while <strong>in</strong>dividual subjects were entered as random<br />

effects. The ANOVA was used to determ<strong>in</strong>e significant differences among the two communities.<br />

Pair‐wise t‐test was used to compare significant difference between the two communities for each<br />

microbiota source. The PCR measurements were log transformed before statistical analysis to<br />

obta<strong>in</strong> normal distribution <strong>of</strong> the data. Normal distribution was assessed us<strong>in</strong>g D'Agost<strong>in</strong>o &<br />

Pearson omnibus normality test. Univariate ANOVA was used to analyze difference <strong>in</strong> the age <strong>of</strong><br />

the three groups us<strong>in</strong>g GraphPad Prism s<strong>of</strong>tware (version 5.03; GraphPad S<strong>of</strong>tware Inc., La Jolla,<br />

California, USA). Tests were considered statistically significant if P‐values lower than 0.05 were<br />

obta<strong>in</strong>ed. Pr<strong>in</strong>cipal Component Analysis (PCA) was carried out us<strong>in</strong>g SAS JMP s<strong>of</strong>tware (version<br />

6.0.2) on the qPCR data to <strong>in</strong>vestigate the difference between lum<strong>in</strong>al and mucosal community<br />

and to address which bacterial taxa may be important for colonization.<br />

Results<br />

Microbial community analysis us<strong>in</strong>g DGGE<br />

Comparison <strong>of</strong> DGGE pr<strong>of</strong>iles conta<strong>in</strong><strong>in</strong>g 16S ribosomal genes amplified from lum<strong>in</strong>al and mucosal<br />

samples <strong>of</strong> healthy subjects and UC patients after 42h colonization revealed a dist<strong>in</strong>ct difference<br />

between the lum<strong>in</strong>al and mucosal environment <strong>in</strong> terms <strong>of</strong> bacterial composition (Figure 2). The<br />

dendrogram from the Dice cluster analysis showed three clusters with five lum<strong>in</strong>al samples <strong>in</strong><br />

cluster I (53.89% similarity), all mucosal samples <strong>in</strong> cluster II (54.61% similarity) and seven lum<strong>in</strong>al<br />

samples <strong>in</strong> cluster III (41.15% similarity). Cluster<strong>in</strong>g did not occur accord<strong>in</strong>g to the health status <strong>of</strong><br />

the human subjects (healthy, UC <strong>in</strong> remission and UC <strong>in</strong> relapse).<br />

8

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