Microsatellite instability typing in serum and tissue of patients with colorectal cancer: comparing real time PCR with hybridization probe and high-performance liquid chromatography.

Allelic variation of BAT-25 (a 25-repeat quasimonomorphic poly T) and BAT-26 (a 26-repeat quasimonomorphic polyA) loci as two mononucleotide microsatellite markers, were analyzed with high-performance liquid chromatography (HPLC) compared with Real-Time PCR using hybridization probes. BAT-26 and BAT-25 markers were used to determine an appropriate screening technique with high sensitivity and specificity to diagnose microsatellite instability (MSI) status in patients with colorectal cancer (CRC). One of the pathways in colorectal tumor genesis is microsatellite instability (MSI+). MSI is detected in about 15% of all CRCs; 3% are of these are associated with Lynch syndrome and the other 12% are caused by sporadic. Colorectal tumors with MSI have distinctive features compared with microsatellite stable tumors. Due to the high percentage of MSI+ CRC in Iran, screening of this type of CRC is imperative. Two markers were analyzed in tissues and sera of 44 normal volunteers and tumor and matched normal mucosal tissues as well as sera of 44 patients with sporadic CRC. The sensitivity and specificity of BAT-26 with real time PCR method (Hybridization probe) were 100% in comparison with sequencing method as the gold standard, while HPLC had a lower sensitivity and specificity. According to HPLC data, BAT-26 was more sensitive than BAT-25 in identifying MSI tumors. Therefore, MSI typing using the BAT-26 hybridization probe method compared to HPLC could be considered as an accurate method for diagnosing MSI in CRC tumors but not in serum circulating DNAs.

Symptom association probability and symptom sensitivity index: preferable but still suboptimal predictors of response to high dose omeprazole.

BACKGROUND: Twenty four hour oesophageal pH monitoring is frequently used to quantify the association between a patient's symptom and gastro-oesophageal reflux. Three indices (symptom association probability (SAP), symptom index (SI), and symptom sensitivity index (SSI)) are used to quantify and establish this relation. AIMS: The aim of the present study was to compare these indices against the omeprazole test (OT) as an objective indicator of reflux induced symptoms. METHODS: Fifty two patients with a predominant symptom of heartburn were enrolled from gastroenterology and primary care clinics. Baseline symptom score was calculated at the fist visit. All patients underwent 24 hour oesophageal pH monitoring, and symptom-reflux association indices were calculated. All patients were placed on high dose omeprazole (40 mg in the morning, 20 mg at night) after completion of pH monitoring and symptom score was recorded again after one week. RESULTS: Thirty eight patients completed the study. All three indices were significantly related to each other (p<0.001). SAP and SSI (with a new cut off of 1.3, but not with the commonly used 5%) had statistically significant relations with OT (p<0.05 for both). SSI had the highest positive and negative predictive values and sensitivity. The specificity of SSI and SAP was equal and lower than SI. Areas under the receiver operating characteristic (ROC) curve for the three indices were not significantly different from each other or from a hypothetical non-discriminating test. Per cent time pH <4, sex, and age had no relation to OT and no effect on its correlation with association indices. No cut off point could be found at which the results of SI could be related significantly to the OT results. CONCLUSION: SAP and SSI are significantly related to symptomatic response to high dose omeprazole; however, they are far from perfect, with a significant number of discordant cases as well as relatively small areas under the ROC curves. We suggest that the new cut off of 1.3 be used for SSI in the future. Further research is needed to identify possible methods to improve the discrimination power of these indices or to identify possible patient characteristics that may affect this relation.

Effect of Helicobacter pylori eradication or of ranitidine plus metoclopramide on Helicobacter pylori-positive functional dyspepsia. A randomized, controlled follow-up study.

BACKGROUND: A definitive treatment for functional dyspepsia (FD), and the role of Helicobacter pylori eradication on the course of this disease are controversial. AIM: To investigate the effect of a combination of acid-suppressing and prokinetic drugs or eradication therapy on the course of H. pylori-positive FD. METHOD: A total of 157 patients with endoscopically-proven H. pylori-positive FD and no response to 4 weeks of antacid therapy were randomly divided into 2 groups. 84 were placed on bismuth subnitrate plus metronidazole and amoxicillin (group A) and 73 received ranitidine and metoclopramide for 4 weeks (group B). The severity of symptoms (7 items) were assessed on a 6-point categorical scale. Group B patients who failed to respond to their medication underwent eradication therapy after 3 months. All patients were followed and assessed for 9 months after the end of therapy by the same clinicians who initiated the therapy. RESULTS: At the end of the medication period, symptom's score decreased significantly, and to the same extent. At 3-month follow-up moderate or complete response was achieved in 27.4% (group A) and 19.2% (group B) by intention-to-treat analysis. 34 patients of group B, not responding to treatment, underwent eradication therapy and followed as group A. Eradication of H. pylori was successful in 60 of 110 controlled patients (54%). After 9-month follow-up, complete or moderate response was observed in only 30% of 60 patients in whom H. pylori had been eradicated (intention-to-treat analysis), compared to 38% in 50 noneradicated cases (p > 0.05, 95% CI: 19-43 vs. 24-52). CONCLUSION: Eradication therapy with bismuth compound is effective as ranitidine plus metoclopramide in a subgroup of patients with FD not responding to antacid therapy. There is no difference in improvement between patients cured or not cured from H. pylori infection. This suggests that bismuth compounds were effective in FD when used in the eradication regimen. Combination therapy with acid-suppressing drugs plus prokinetic and bismuth seems to hold promise for FD.