Studies On The Plasma DNA Quantification And The Gene Expression Profiles Of Patients With Acute Pancreatitis

Part 1: Quantitative analysis of plasma DNA from patients with acute pancreatitis and its potential clinical valueObjective To quantify the plasma DNA from patients with acute pangreatitis and evaluate its potential clinical significance. Methods Blood samples collected from 40 patients with mild acute pancreatitis(MAP), 20 with severe acute pancreatitis(SAP), and 50 healthy controls were extracted for plasma DNA using"genomic DNA extraction kit". The quantitation of plasma DNA was performed by real-time fluorescence quantitative PCR assay. The clinical association of DNA level with acute pancreatitis was analyzed. Screening performance of the assay was calculated through the receiver operating characteristic(ROC)curve. Results The median concentration of circulating plasma DNA in SAP group was 24.84ng/ml, which was significantly higher than that in MAP group (7.60ng/ml, P=0.006) and the healthy controls (5.23ng/ml, P=0.000). The median concerntration of plasma DNA in patients with acute pancreatitis was higher than in healthy controls (P=0.006). However, there was no significant difference between MAP group and healthy controls (P=0.322). The area under the ROC curve performed by the plasma DNA from SAP and MAP groups was 0.881(95%CI, 0.773～0.989). With a cutoff value of 11.20ng/ml, the overall sensitivity was 95% and specificity was 72.5%. Plasma DNA level was found to be associated with APACHE-Ⅱscore (P=0.001), Ranson score (P=0.013), serum Ca2+ level (P=0.000), and CRP levels (P=0.001), but not to length of hospitalization and leucocyte counts. Conclusion Plasma DNA level correlates with the extent of pancreatitis. It can be used in monitoring the development of acute pancreatitis and may be a potential marker for early diagnosis of severe acute pancreatitis. Part 2: Study on the gene expression profiles of peripheral blood monocyte(PBMC) from patients with acute pancreatitisObjective To initially survey the changes of peripheral blood monocyte from patients with acute pancreatitis, and to explore the mechanism of SAP. Methods PBMC from patients with acute pancreatitis and healthy controls were envolved in this study. The total RNA of them was extracted. Hybridization with Human Genome Array was performed. Gene sets shared in two independent comparisons(SAP vs MAP, SAP vs healthy control) were selected in our study by bioinfomatic and literature mining methods. They were thought to be SAP associated genes. Results By the comparison between SAP and healthy controls, we observed 2574 alternatives(above two fold), which included 1193 up-regulated genes and 1381 down-regulated genes. Similarly, by the comparison between SAP and MAP, 755 differently expressed genes were found, including 480 up-regulated ones and 275 down-regulated ones. SAM analysis was performed to identify the most discriminating genes. 413 genes were extracted as gene expression patern of SAP,including 305 up-regulated genes and 108 down-regulated ones. The functions of these related genes were involved in biological regulation, response to stimulus, signaling process, immune response, cell death, cell adhension and so on. Conclusion The differently expressed genes between SAP and healthy controls were initially identified by the gene chip, which was the basement of further exploration. The gene sets shared in two independent comparisons(SAP vs MAP, SAP vs healthy control) may be related with the biological behavior of SAP.