Authors' response

Author's Response to H.M. Heneghan, N. Miller, M.J. Kerin, Systemic microRNAs: novel biomarkers for colorectal and other cancers?, 2010, v. 59 n. 7, p. 1002-1004postprin

Evaluation of the string test for the detection of Helicobacter pylori

Aim: Helicobacter pylori can be diagnosed by invasive or non-invasive tests but to obtain bacteria for culture and antibiotic susceptibility testing, an upper GI endoscopy is often required. The string test may be a minimally-invasive alternative method of obtaining H. pylori samples. This study evaluates the sensitivity and specificity of the string test in the diagnosis of H. pylori in comparison with endoscopic means of diagnosis. Methods: This was a prospective open comparative study of patients with dyspepsia with endoscopy-based tests as gold standard (defined as a positive CLO test and antral histology). Fasting patients swallowed the encapsulated-string (Entero-test Hp), which was withdrawn after 1 hour. The gastric juice from the string was plated onto H. pylori-selective media for culture. Helicobacter pylori was identified by typical colony morphology, gram stain and biochemical test results. Results: Thirty dyspeptic patients were recruited of whom 21 (70 %) were positive for H. pylori according to the gold standard. The sensitivity, specificity, positive predictive value, and negative predictive value for the string test were 38 %, 100 %, 100 % and 41 % respectively, and for endoscopic biopsies 81 %, 100 %, 100 %, 69 % respectively (P=0.004). Logistic regression showed that only abundant growth density from endoscopic biopsy cultures to be a predictor of a positive string test (P=0.018). Conclusion: The string test is an alternative method to endoscopy in obtaining H. pylori but has a low sensitivity compared to endoscopic biopsies.published_or_final_versio

Effect of oral erythromycin on gastric and small bowel transit time of capsule endoscopy

Aim: To determine the effect of oral erythromycin on gastric and small bowel transit time of capsule endoscopy. Methods: Consecutive patients who underwent capsule endoscopy during the 16-mo study period were either given 250 mg oral erythromycin, 1 h prior to swallowing the capsule endoscope or nothing. The gastric and small bowel transit time, and the small bowel image quality were compared. Results: Twenty-four patients received oral erythromycin whereas 14 patients were not given any prokinetic agent. Patients who received erythromycin had a significantly lower gastric transit time than control (16 min vs 70 min, P = 0.005), whereas the small bowel transit time was comparable between the two groups (227 min vs 183 min, P = 0.18). Incomplete small bowel examination was found in three patients of the control group and in one patient of the erythromycin group. There was no significant difference in the overall quality of small bowel images between the two groups. A marked reduction in gastric transit time was noted in two patients who had repeat capsule endoscopy after oral erythromycin. Conclusion: Use of oral erythromycin significantly reduces the gastric transit time of capsule endoscopy. © 2005 The WJG Press and Elsevier Inc. All rights reserved.published_or_final_versio

Follow up of serial urea breath test results in patients after consumption of antibiotics for non-gastric infections

Aim: The widespread use of antibacterial therapy has been suggested to be the cause for the decline in the prevalence of Helicobacter pylori infection. This study examine the serial changes of urea breath test results in a group of hospitalized patients who were given antibacterial therapy for non-gastric infections. Methods: Thirty-five hospitalized patients who were given antibacterial therapy for clinical infections, predominantly chest and urinary infections, were studied. Most (91 %) patients were given single antibiotic of either a penicillin or cephalosporin group. Serial 13C-urea breath tests were performed within 24 hours of initiation of antibiotics, at one-week and at six-week post-therapy. H. pylori infection was diagnosed when one or more urea breath tests was positive. Results: All 35 patients completed three serial urea breath tests and 26 (74 %) were H. pylori-positive. Ten (38 %) H. pylori-infected patients had at least one negative breath test results during the study period. The medium delta 13C values were significantly lower at baseline (8.8) than at one-week (20.3) and six-week (24.5) post-treatment in H. pylori-positive individuals (P=0.022). Clearance of H. pylori at six-week was only seen in one patient who had received anti-helicobacter therapy from another source. Conclusion: Our results suggested that one-third of H. pylori-infected individuals had transient false-negative urea breath test results during treatment with antibacterial agent. However, clearance of H. pylori infection by regular antibiotic consumption is rare.published_or_final_versio

Clinical significance of hepatic derangement in severe acute respiratory syndrome

Aim: Elevation of alanine aminotransferase (ALT) level is commonly seen among patients suffering from severe acute respiratory syndrome (SARS). We report the progression and clinical significance of liver derangement in a large cohort of SARS patient. Methods: Serial assay of serum ALT was followed in patients who fulfilled the WHO criteria of SARS. Those with elevated ALT were compared with those with normal liver functions for clinical outcome. Serology for hepatitis B virus (HBV) infection was checked. Adverse outcomes were defined as oxygen desaturation, need of intensive care unit (ICU) and mechanical ventilation and death. Results: Two hundred and ninety-four patients were included in this study. Seventy (24%) patients had elevated serum ALT on admission and 204 (69%) patients had elevated ALT during the subsequent course of illness. Using peak ALT >5×ULN as a cut-off and after adjusting for potential confounding factors, the odds ratio of peak ALT >5× ULN for oxygen desaturation was 3.24 (95%CI 1.23-8.59, P = 0.018), ICU care was 3.70 (95%CI 1.38-9.89, P = 0.009), mechanical ventilation was 6.64 (95%CI 2.22-19.81, P = 0.001) and death was 7.34 (95%CI 2.28-24.89, P = 0.001). Ninety-three percent of the survived patients had ALT levels normalized or were on the improving trend during follow-up. Chronic hepatitis B was not associated with worse clinical outcomes. Conclusion: Reactive hepatitis is a common complication of SARS-coronavirus infection. Those patients with severe hepatitis had worse clinical outcome. © 2005 The WJG Press and Elsevier Inc. All rights reserved.published_or_final_versio

Differential expression of microRNAs in plasma of patients with colorectal cancer: A potential marker for colorectal cancer screening

Objective: MicroRNAs (miRNAs) have been shown to offer great potential in the diagnosis of cancer. We investigated whether plasma miRNAs could discriminate between patients with and without colorectal cancer (CRC). Methods: This study was divided into three phases: (1) marker discovery using real-time PCR-based miRNA profiling on plasma, corresponding cancerous and adjacent non-cancerous colonic tissues of five patients with CRC, along with plasma from five healthy individuals as controls; (2) marker selection and validation by real-time quantitative RT-PCR on a small set of plasma; and (3) independent validation on a large set of plasma from 90 patients with CRC, 20 patients with gastric cancer, 20 patients with inflammatory bowel disease (IBD) and 50 healthy controls. Results: Of the panel of 95 miRNAs analysed, five were upregulated both in plasma and tissue samples. All the five miRNAs were validated on the plasma of 25 patients with CRC and 20 healthy controls. Both miR-17-3p and miR-92 were significantly elevated in the patients with CRC (p<0.0005). The plasma levels of these markers were significantly reduced after surgery in 10 patients with CRC (p<0.05). Further validation with an independent set of plasma samples (n=180) indicated that miR-92 differentiates CRC from gastric cancer, IBD and normal subjects. This marker yielded a receiver operating characteristic curve area of 88.5%. At a cut-off of 240 (relative expression in comparison to RNU6B snRNA), the sensitivity was 89% and the specificity was 70% in discriminating CRC from control subjects. Conclusion: MiR-92 is significantly elevated in plasma of patients with CRC and can be a potential non-invasive molecular marker for CRC screening.published_or_final_versio

microRNA-29b prevents liver fibrosis by attenuating hepatic stellate cell activation and inducing apoptosis through targeting PI3K/AKT pathway

microRNA-29b (miR-29b) is known to be associated with TGF-β-mediated fibrosis, but the mechanistic action of miR-29b in liver fibrosis remains unclear and is warranted for investigation. We found that miR-29b was significantly downregulated in human and mice fibrotic liver tissues and in primary activated HSCs. miR-29b downregulation was directly mediated by Smad3 through binding to the promoter of miR-29b in hepatic stellate cell (HSC) line LX1, whilst miR-29b could in turn suppress Smad3 expression. miR-29b transduction in the liver of mice prevented CCl4 induced-fibrogenesis, concomitant with decreased expression of α-SMA, collagen I and TIMP-1. Ectopic expression of miR-29b in activated HSCs (LX-1, HSC-T6) inhibited cell viability and colony formation, and caused cell cycle arrest in G1 phase by downregulating cyclin D1 and p21cip1. Further, miR-29b induced apoptosis in HSCs mediated by caspase-9 and PARP. miR-29b inhibited its downstream effectors of PIK3R1 and AKT3 through direct targeting their 3'UTR regions. Moreover, knockdown of PIK3R1 or AKT3 suppressed α-SMA and collagen I and induced apoptosis in both HSCs and in mice. In conclusion, miR-29b prevents liver fibrogenesis by inhibiting HSC activation and inducing HSC apoptosis through inhibiting PI3K/AKT pathway. These results provide novel mechanistic insights for the anti-fibrotic effect of miR-29b.published_or_final_versio

Different cell kinetic changes in rat stomach cancer after treatment with celecoxib or indomethacin: Implications on chemoprevention

Aim: Mechanisms underlying the chemopreventive effects of cyclooxygenase (COX) inhibitors remain elusive. We have previously shown that celecoxib but not indomethacin could prevent carcinogen-induced gastric cancer development in Wistar rats. This chemopreventive effect appeared to be independent of COX-2 and prostaglandin (PG) E2 suppression since the lowest PGE2 was obtained in indomethacin group. This study compared the cell kinetic changes in stomachs of rats after treatment with celecoxib (5, 10, 20 mg/(kg·d)) or indomethacin (3 mg/(kg·d)) to gain more insights into the chemopreventive mechanism. Methods: The apoptosis and proliferation indexes in gastric tumor, adjacent non-cancer tissues and normal gastric tissues were determined. Apoptosis was quantified by apoptotic nuclei counting and TUNEL, whereas proliferation was determined by Ki67 immunostaining. Results: Treatment with either celecoxib or indomethacin inhibited gastric tumor proliferation by more than 65% (P<0.02). However, celecoxib caused a dose-dependent increase in apoptosis (P<0.05) which was not seen in indomethacin-treated tumors (P = 0.54). The highest apoptosis to proliferation ratio was seen in tumors treated with celecoxib at 10 mg/(kg·d). Treatment with this dose of celecoxib was associated with the lowest incidence of gastric cancer development. Conclusion: Our findings suggest that the difference in chemopreventive effects of indomethacin and celecoxib in this animal model of gastric carcinogenesis is largely due to the differential cell kinetic changes, which does not correlate with the degree of COX-2 and PG suppression. © 2005 The WJG Press and Elsevier Inc. All rights reserved.published_or_final_versio