Christos Liatsos

Relationship of Helicobacter pylori CagA status to gastric cell proliferation and apoptosis.

Despite the fact that the association ofHelicobacterpylori with an increased risk of gastriccancer is well documented, the exact mechanisms of thisassociation have not been elucidated. Our aim was to shed some light on these mechanisms by studyingThe relationship of H. pylori CagA status to gastriccell proliferation and apoptosis, since both play animportant role in gastrointestinal epithelial cell turnover and carcinogenesis. We studied fiftypatients [32 men, 18 women, median age 39.5 years (range18-67)], referred for upper gastrointestinal endoscopy,from whom antral biopsies were taken. On biopsy specimens gastritis was estimated byscoring the severity of inflammatory infiltrate, and thepresence of atrophy and intestinal metaplasia were alsonoted. The gastric cell proliferation index (PI) was estimated by AgNOR staining, the epithelialapoptotic index (AI) was measured by special stainingfor apoptosis, and CagA status was determinedserologically by immunoblotting the sera of patientsagainst H. pylori antigens. Thirty-eight (76%) of the50 patients were H. pylori (positive) and 12 (24%) H.pylori (negative). Among the 38 H. pylori (+) patients,28 (73.6%) were CagA(+) and 10 (24.6%) CagA(-). In the H. pylori CagA(+) and CagA(-) groups,the PI values [median (ranges)] were 5 (4-7) and 3.7(3.5-5.5), respectively (P < 0.05). In addition thedifference in PI between the H. pylori CagA(+) and H. pylori (-) groups was highly significant (P< 0.001). Concerning apoptosis, in the H. pyloriCagA(+) and CagA(-) groups, the values for AI were 1(1-30) and 5.5 (1-35), respectively (P < 0.05). In addition, the difference in AI between theH. pylori CagA(-) and H. pylori (-) groups, wassignificant (P < 0.05). We conclude that H. pyloriCagA(+) strains induce increased gastric cellproliferation, which is not accompanied by a parallel increasein apoptosis. This might explain the increased risk forgastric carcinoma that is associated with infection byH. pylori CagA(+) strains.

Biliary stenting alone versus biliary stenting plus sphincterotomy for the treatment of post-laparoscopic cholecystectomy biliary leaks: a prospective randomized study.

Objective Although various endoscopic techniques have been proved effective in treating post-cholecystectomy biliary leaks, the choice of the best method remains controversial. The aim of this prospective study was to compare the efficacy and safety of biliary stenting alone with biliary stenting plus sphincterotomy for the treatment of post-cholecystectomy biliary leaks. Methods Patients with post-laparoscopic cholecystectomy leaks were randomized into two groups. The first group included 24 patients who were treated with a 7 Fr biliary stent alone, and the second group included 28 patients who underwent an endoscopic sphincterotomy followed by insertion of a 10 Fr biliary stent. Results Endoscopic therapy was successful in all patients (100%). Clinical improvement was observed after 2–6 days. Patients remained hospitalized for 4–12 days. Stents were removed after 6.7 (6–8) weeks. The overall complication rate was 4.16% for the first group and 10.71% for the second (P=0.615). No complications were recorded during the follow-up period. Conclusions Endoscopic therapy of biliary leaks with a small-diameter biliary stent alone is as effective and safe as endoscopic sphincterotomy followed by insertion of a large-diameter stent.

Endoscopic variceal ligation vs. propranolol for prevention of first variceal bleeding : a randomized controlled trial

Objectives Data in the literature regarding the role of endoscopic variceal ligation for the prevention of first variceal bleeding in cirrhotic patients are controversial. To further explore this issue we have compared ligation and propranolol treatment in a prospective randomized study. Methods Sixty patients with cirrhosis and oesophageal varices with no history but at high risk of bleeding were randomized to ligation treatment (30 patients) or propranolol (30 patients). Patients were followed for approximately 27.5 months. Results Variceal obliteration was achieved in 28 patients (93.3%) after 3±1 sessions. The mean daily dose of propranolol was 60.3±13.3 mg. Two patients (6.7%) in the ligation group and nine patients (30%) in the propranolol group developed variceal bleeding (P=0.043). The actuarial risks of variceal bleeding at 2 years were 6.7% and 25%, respectively. On multivariate analysis, propranolol treatment and grade III varices turned out to be predictive factors for the risk of variceal bleeding. Mortality was not different between the two groups. There were no serious complications due to ligation. Propranolol treatment was discontinued in four patients because of side effects. Conclusions Variceal ligation is a safe and more effective method than propranolol treatment for the prevention of first variceal bleeding in cirrhotic patients with high-risk varices.

Enhancement of bowel sounds by wavelet-based filtering

This paper evaluates the performance of an automatic method for structural decomposition, noise removal and enhancement of bowel sounds (BS), based on the wavelet transform. The proposed method combines multiresolution analysis with hard thresholding to compose a wavelet transform-based stationary-nonstationary (WTST-NST) filter, for enhanced separation of bowel sounds (BS) from superimposed noise. Quantitative and qualitative analysis of the experimental results, when applying the WTST-NST filter to BS recorded from controls and patients with gastrointestinal dysfunction, prove that the ability of the WTST-NST filter to remove noise and reveal the authentic structure of BS is excellent. By eliminating the need to record a noise reference signal, this method reduces hardware overhead when analysis of BS is the primary aim. The method is independent of subjective human judgement for selection of noise reference templates, is robust to different levels of signal interference, and, due to its simplicity, can easily be used in clinical medicine.

Comparison of two schemes of small bowel preparation for capsule endoscopy with polyethylene glycol: a prospective, randomized single-blind study.

Objective Small bowel preparation for capsule endoscopy remains controversial. This study was conducted to compare the efficacy of 2 and 4 l of polyethylene glycol. Methods One hundred and one patients (group A) received 2 l and 100 (group B) received 4 l in a prospective, randomized single-blind trial. To objectively evaluate enteric preparation, a cleansing coefficient was calculated for each patient. Results The two groups were found comparable regarding age, sex, body mass index, and reason for referral. In 82 patients of group A and in 76 of group B, examination of small bowel was completed (P=0.40). Gastric emptying time and small bowel transit time were found comparable in both groups. Cleansing coefficients, for small bowel as a whole or for proximal or distal separately, were similar among the two groups. However, the cleansing coefficient of the proximal bowel was significantly higher than that of the distal, independently of preparation (group A: P<0.001, group B: P<0.001). Small bowel preparation was related only with the age of the patients and gastric emptying time; the younger the patient or the shorter the gastric emptying time, the higher the cleansing coefficient. Pathological findings were found in 43 (42.6%) patients of group A and in 37 (37.0%) patients of group B (P=0.42). A final positive diagnosis was established in 33 (32.7%) patients of group A and in 29 (29.0%) of group B (P=0.57). Conclusion The two schemes were equal regarding enteric cleansing and completion of the procedure. Therefore, 2 l seems to be an adequate preparation for capsule endoscopy.

The association between CagA status and the development of esophagitis after the eradication of helicobacter pylori

BACKGROUND Strains of Helicobacter pylori with the cytotoxine-associated gene A (cagA) are linked to severe forms of gastroduodenal disease. Although eradication of H. pylori may predispose to the development of reflux esophagitis, the effects of CagA status on risk of esophagitis after successful H. pylori treatment are not known. METHODS We studied 50 consecutive patients without esophagitis in whom H. pylori was eradicated successfully. CagA status was determined by immunoblotting sera from patients against H. pylori antigens. Patients underwent upper gastrointestinal endoscopy before eradication and 6, 12, 18, and 24 months after eradication or when reflux symptoms occurred. Biopsy specimens of the antrum and corpus were evaluated for gastritis before H. pylori eradication and at the end of the study. The sum of the scores for acute and chronic inflammation (both measured on a 0 [absent] to 3 [severe] scale) comprised the total gastritis severity score. RESULTS In a multivariate proportional hazards regression analysis, positive CagA serology (hazard ratio [HR] = 10, 95% confidence interval [CI]: 1.3 to 81) and moderate-to-severe corpus gastritis (total severity score > or =4) before eradication (HR = 2.3, 95% CI: 1.2 to 6.1) were independent risk factors for the development of esophagitis after H. pylori eradication. CONCLUSION Patients infected with strains of H. pylori that are cagA-positive are at increased risk of developing esophagitis after eradication of H. pylori.

Evaluation of four time-saving methods of reading capsule endoscopy videos.

Objective Review of wireless capsule endoscopy recordings is time consuming. The aim of this study was to evaluate four time-saving methods offered with Rapid Software. Methods A total of 100 wireless capsule endoscopy videos with abnormal findings were evaluated using five different ways of viewing: (a) manual mode at a speed of 10 frames per second (fps), (b) manual mode at a speed of 20 fps, (c) manual mode with a simultaneous display of two images at a speed of 20 fps, (d) automatic mode at a speed of 10 fps, and (e) quickview mode at a speed of 3 fps. Then, we calculated the concordance of abnormal findings between each one of the four time-saving methods using method A. Results The mean reading time with time-saving methods was significantly shorter than with method A (method A: 59.8 min, method B: 30 min, method C: 30.2 min, method D: 32.2 min, method E: 16.3 min). The agreement in finding abnormal lesions between method A and the four evaluated methods was excellent and almost perfect (&kgr;>0.8), except for quickview in recognizing polyps. Diagnostic miss rate was 1% for method D, 2% for B and C, and 12% for E. No tumors and cases of celiac or Crohn’s disease were lost by all four methods. Conclusion We conclude that manual mode/20 fps, the simultaneous projection of two images/20 fps, and automatic mode/10 fps have minimal diagnostic miss rates and can safely replace slower modes in clinical practice. The quickview mode is a safe diagnostic tool only when larger or diffuse lesions are suspected, such as Crohn’s or celiac disease.

Safety of extension of a previous endoscopic sphincterotomy: a prospective study

OBJECTIVES:Data in the literature regarding complication risks after the extension of a previous endoscopic biliary sphincterotomy (repeat endoscopic biliary sphincterotomy) are limited and controversial. To explore this issue, we prospectively studied complications after repeat sphincterotomy and compared them with those of biliary endoscopic sphincterotomy in consecutive patients with choledocholithiasis.METHODS:A total of 250 patients underwent endoscopic biliary sphincterotomy and 81 underwent extension of a previous one. All patients had choledocholithiasis and were enrolled using specific criteria, excluding parameters predisposing to increased postsphincterotomy complications.RESULTS:The overall complication rate was 2.46% in the repeat sphincterotomy and 8.4% in the sphincterotomy group (p > 0.05). Complications for the repeat sphincterotomy and initial sphincterotomy groups, respectively, were as follows: bleeding, 2.46% and 2.8%; pancreatitis, 0% and 4.8% (p < 0.05); cholangitis, 0% and 0.4%; perforation, 0% and 0.4%; and hyperamylasemia, 3.7% and 12.8% (p < 0.05). There were no deaths. Bleeding episodes in the former group occurred when repeat sphincterotomy was performed early after the primary one.CONCLUSIONS:Repeat sphincterotomy is a safe technique for the treatment of patients with choledocholithiasis and seems to be as safe as initial sphincterotomy. It is not associated with increased hemorrhage risk. There is a trend toward a higher risk of hemorrhage when repeat sphincterotomy is performed early. Repeat sphincterotomy is safer than the initial sphincterotomy with respect to pancreatic complications.

Capsule endoscopy image analysis using texture information from various colour models

Wireless capsule endoscopy (WCE) is a novel imaging technique that is gradually gaining ground as it enables the non-invasive and efficacious visualization of the digestive track, and especially the entire small bowel including its middle part. However, the task of reviewing the vast amount of images produced by a WCE examination is a burden for the physicians. To tackle this major drawback, an innovative scheme for discriminating endoscopic images related to one of the most common intestinal diseases, ulceration, is presented here. This new approach focuses on colour-texture features in order to investigate how the structure information of healthy and abnormal tissue is distributed on RGB, HSV and CIE Lab colour spaces. The WCE images are pre-processed using bidimensional ensemble empirical mode decomposition so as to facilitate differential lacunarity analysis to extract the texture patterns of normal and ulcerous regions. Experimental results demonstrated promising classification performance (mean accuracy>95%), exhibiting a high potential towards automatic WCE image analysis.

Predictive factors and prevalence of follicular gastritis in adults with peptic ulcer and nonulcer dyspepsia

Follicular gastritis is an importanthistological entity, because it may progress to overtgastric MALT lymphoma. However, there is no universalagreement on whether there is any correlation offollicular gastritis with histological features of theantral mucosa or on the prevalence of folliculargastritis. To shed further light on these issues, westudied antral biopsies obtained from 735 adultpatients, who had participated in six consecutiveclinical trials. They included 348 patients withduodenal ulcer, 82 with gastric ulcer, and 305 withnonulcer dyspepsia. The Sydney classification system ofgastritis was used, using a score of 0-3 to grade degreeand activity of inflammation, gland atrophy, intestinalmetaplasia, and H. pylori colonization density.Follicular gastritis was defined as prominent lymphoid follicles with no lymphoepithelial lesion. Noneof the H. pylori-negative patients (N = 159) hadfollicular gastritis. Among H. pylori-positive patients,80/340 (23.5%) with duodenal ulcer, 5/77 (6.5%) withgastric ulcer, and 20/159 (12.6% ) with nonulcerdyspepsia had follicular gastritis (P < 0.001).Multivariate discriminant analysis selected thefollowing four significant predictor variables for follicular gastritis (Wilks λ =0.91, x2 = 70.6, df = 4, P < 0.001):gastritis sum score, atrophic gastritis, age of thepatient, and disease. The prevalence of folliculargastritis was linearly correlated (y = 24.55 – 0.98x, r =–0.62, F1,11 = 6.12, P = 0.03) with theage groups of the 576 H. pylori-positive patientsstudied. In conclusion, follicular gastritis is highlycorrelated with H. pylori-caused severe, activegastritis. It is mostly prevalent in the young H.pylori-infected patients with duodenal ulcer.