Helicobacter pylori infection: several studies on epidemiology, eradication and gastric epithelial cell turnover Liu, W.

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1 UvA-DARE (Digital Academic Repository) Helicobacter pylori infection: several studies on epidemiology, eradication and gastric epithelial cell turnover Liu, W. Link to publication Citation for published version (APA): Liu, W. (1999). Helicobacter pylori infection: several studies on epidemiology, eradication and gastric epithelial cell turnover General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam ( Download date: 18 Jan 2018

2 CHAPTER 1 General Introduction Wen-Zhong Liu Shanghai Institute of Digestive Disease, Shanghai Second Medical University, Shanghai

3 INTRODUCTION Helicobacter pylori was brought to the world attention in 1983 when Warren and Marshall, two Australian investigator, reported isolation of spiral organisms from mucosal biopsy specimens of patients with chronic active gastritis and pepetic ulcer disease(l). Now the organism is accepted as the causative agent of gastritis, peptic ulcer disease, gastric adenocarcinoma and gastric B-cell lymphoma (MALT lymphoma). H. pylori infection may also play a role in some cases of nonulcer dyspepsia. H. pylori-related diseases are among the most prevalent in the world. This chapter will review the literature of H, pylori infection in the epidemiology, eradication and its relation with gastric epithelial cell turnover. EPIDEMIOLOGY H. pylori infects more than half the people in the world. The prevalence of infection varies among countries and among different groups within the same country (2-11). In developing countries the infection rates are much higher, compared with those of developed countries. In all areas of the world the infection rate increases with age. In developed countries less than 10% of the children are infected with H. pylori; the prevalence of infection increases to approximately 60% at the age of 60 or above. In developing countries about 50% of the children are infected with H. pylori and infection rate increases with age up to 70-80% in adulthood. The highest rates of infection are associated with low socio-economic status, crowding, poor sanitation and unclean water supplies (5-7,11). Although H. pylori has been isolated from cats (12) and non-human primates (13), these animals do not seem to be a natural reservoir (14). Most data suggest that the organism is transmitted from person to person. Support for this concept comes from studies that infection rates are higher in institutions (15,16) and H pylori strains within families are closely related (17-20). The exact means by which H. pylori is transmitted

4 among individuals is uncertain (21) and arguments can be made for and against each possibility. The first possibility is fecal-oral transmission. H. pylori has been detected in stool by polymerase chain reaction (PCR) (22) and culture (23, 24). Unfortunately, culture of H. pylori from stool has proved to be extremely difficult, and detection by PCR does not ensure that the organisms are living. Further evidence against fecal-oral transmission comes from studies in mice infected with H. felis, in which infection could not be transmitted from infected mice to coprophageous uninfected mice. A second possibility is oral-oral routes, for which evidence of H. pylori in dental plaque and saliva has been found by culture (25,26) and PCR (27). Evidence against oral-oral transmission is that couples without children have a low prevalence of concordance of H. pylori infection (28) and dental staff are not at increased risk of infection (29). A third mean of transmission is gastro-oral (30). Evidence to support such a model include well-described epidemics of Hpylori gastritis in volunteers undergoing gastric intubation experiments (31-33), transmission of infection from one patient to another by inadequately disinfected endoscopes (34,35) and a higher-than-expected prevalence of H pylori among gastroenterologists (36-40), especially those who had not worn gloves in the past. It appears that any mechanism that allows H. pylori enter the stomach of an uninfected host probably is a route of transmission. ERADICATION OF HELICOBACTER PYLORI INFECTION Treatment of H. pylori infection is recommended in patients with peptic ulcer disease, MALT lymphoma, gastritis with severe abnormalities and post early gastric cancer resection (41-43). Cure of H. pylori infection is not easy, and requires combinations of one or two antibiotics with one or two nonantibiotic adjunctive agents. Single agents are ineffective. Cure of infection is defined as absence of the organism by tests performed no sooner than 4 weeks after cessation of antimicrobial therapy (44). Because proton pump inhibitors (PPIs) alone can suppress the infection, PPI therapy

5 should be discontinued for at least 1 week before evaluation of effectiveness of therapy. Although a cure rate of 80% was once considered acceptable, rates of 90% or higher are now achievable, especially if the organism is susceptible to the antibiotics used. Antibiotics Used in Regimens to Eradicate H. pylori Amoxicillin H. pylori is very sensitive in vitro to this antibiotic (45), but in vivo it has little effect when used as monotherapy (46). This may be a result of relative inactivity of the antibiotic at acidic ph. Better results are achieved if antisecretory agents are given with amoxicillin-containing regimens (47). Resistance to amoxicillin has been observed, but is rare. The most common side effects are rash, candidiasis, and diarrhea. Tetracycline Tetracycline is effective in vitro against H. pylori and is active at low ph, and resistance has not yet reported. It is quite useful as a part of triple therapy with bismuth and metronidazole (48) but is contraindicated in children because of the staining of teeth. Metronidazole Metronidazole is actively secretory into gastric juice and saliva, and whose activity is independent of ph. Primary resistance of H. pylori to metronidazole is generally associated with a reduction in cure rates (49) This is important, because the frequency of primary resistance to metronidazole is increasing substantially throughout the world (50-53). Side effects of metronidazole include a metallic taste, diarrhea, and nausea, the latter occurring primarily at doses over lg/day. Tinidazole, a nitroimidazole, produces results that are comparable with those of metronidazole. Clarithromycin This antibiotic is a macrolide with an antibacterial spectrum similar to that of erythromycin but is more acid stable, better absorbed, and more active against H.

6 pylori (54,55). When given as monotherapy in a dose of 2000mg/day, clarithromycin cured H. pylori infection in about 50% of patients(56). As with metronidazole, H. pylori can become resistant to clarithromycin, although primary resistance to clarithromycin is found less frequently than resistance to metronidazole (57,58). Its main side effect is taste perversion. Furazolidone Furazolidone, a nitrofuran, is an old drug with clinical use for over 40 years. It was used in China for the treatment of peptic ulcer disease long before H. pylori was discovered as an causative agent in this disease(59, 60). In the last decade, furazolidone has been found to be effective for eradication of H. pylori (61-69). When given as monotherapy in a dose of 300mg/day for 3 weeks, furazolidone cured H. pylori infection in about 50% of patients (62). This results is comparable with that of clarithromycin. Resistance to furazolidone has not yet been observed in vitro serial passage and in vivo studies(62, 70). Side effects include dizziness, rash and nausea.. Adjunctive Agents Used in Regimens to Treat H. pylori Infection Bismuth. Bismuth compounds are topical antimicrobial agents that act directly on bacterial cell walls to disrupt their integrity by accumulating in the periplasmic spaces and along membranes(71). Bismuth is available as bismuth subsalicylate.(united States) and colloidal bismuth subcitrate (elsewhere ). Side effects with these two bismuth compounds are minimal, although blackening of the stool may occur. Proton-pump Inhibitors. Omeprazole may be used as a model for all PPIs. Although omeprazole has bacteriostatic activity against H. pylori both in vitro and in vivo (72,73), it is especially useful as part of combination therapy with antimicrobial agents to cure H. pylori infection (74-77). One major activity is related to increasing intragastric ph, which

7 may enhance the effectiveness of the local immune response, reduce the washout of antibiotics from the mucosa, and improve the minimal inhibitory concentrations of phsensitive antibacterial agents. The decrease in gastric juice volume that results from these antisecretory drugs may also increase intragastric concentration of antibacterial agents. H 2 Receptor Antagonists. This class of drugs has long been used to promote healing of peptic ulcers. They have no effect by themselves against H. pylori, but they have been used in some studies instead of PPIs in combination with antibiotics(78). Ranitidine Bismuth Citrate (RBC). This is a novel compound with characteristics of both ranitidine and bismuth. RBC is useful when combined with antibiotics, such as clarithromycin (79,80). Side effects are minimal. Therapeutic Regimens to Treat H. pylori Infection Dual Therapy This combination consists of an antibiotic plus a PPI or RBC. The regimen initially touted was amoxicillin plus omeprazole. Initial studies suggested that infection was cured in over 80% of patients (81) and one study involving a very high dose of omeprazole reported over 95% cured (82). However, such good results have not been confirmed (83-85) and this regimen can no longer be recommended. Although more consistent results have been achieved with clarithromycin plus omeprazole or RBC with cure rates after 14 days of therapy of about %(86-88), they do not achieve the goal of a 90% cure rate. Triple Therapy Traditional bismuth triple therapy consisting of bismuth, metronidazole and tetracycline produces cure rates of 85% to 90%, especially with organisms sensitive to 10

8 metronidazole(49,89). Amoxicillin should be substituted for tetracycline in children to avoid staining of teeth. Depending on the dose of metronidazole, over 30% of patients taking this regimen report some side effect (i.e., nausea, sore mouth, taste disturbance, diarrhea, and Candida infection), which results in cessation of treatment in about 5% of patients (90). These side effects and the increasing prevalence of H. pylori strains resistant to metronidazole make this otherwise excellent regimen less desirable. More recent studies have combined two antibiotics with a PPI (PPI-based triple therapy) with generally good results so far. One early study found that a combination of clarithromycin, tinidazole and omeprazole for 1 week cured H. pylori infection in 95% patients (91). A large European trial compared five different regimens containing two antibiotics plus omeprazole given for 7 days (76). Best results were achieved with combinations containing clarithromycin plus either amoxicillin or metronidazole. Two antibiotics plus RBC is be more effective than clarithromycin alone plus RBC, with the results comparable with PPI-based triple therapies (88, 92). Short-term triple therapies containing furazolidone, clarithromycin plus either bismuth or PPI give high cure rates of Helicobacter pylori Infection, furazolidone may become an efficacious alternative to metronidazole in light of a world-wide increase in H. pylori resistance to metronidazole (68,69). Quadruple Therapy Several studies have added an antisecretory agent to traditional bismuth triple therapy. Early studies of traditional bismuth triple therapy with omeprazole (PPI quadruple therapy) have shown cure rates of over 95% after only 7 days of therapy(93). It has also been suggested that results with such a regimen may be only minimally affected by metronidazole-resistant organism (94). Therapeutic Strategy The important factors in selecting therapy are efficacy of eradication, prevention 11

9 of resistance, avoidance or minimization of adverse effects, patient compliance, and cost. The most effective regimens for curing H. pylori infection are combinations of two antibiotics and one or two adjunctive agents taken for 7 to 14 days. Dual therapies are not recommended. Triple or quadruple regimens are more likely to eradicate H pylori and less likely to generate resistant strains among surviving organisms. Antibiotic resistance is an important consideration in choosing therapy, resistance to metronidazole or clarithromycin may lead to reduced efficacy with either antibiotic. When treatment fails, antibiotic combinations should not be repeated. Compliance is important for successful cure of the infection. Thus regimens should be designed so that side effects that may reduce compliance are minimized. H. PYLORI INFECTION AND GASTRIC EPITHELIAL TURNOVER Although International Agency for Research on Cancer has classified H. pylori as a class I carcinogen in 1994(95), some investigator still feel that this conclusion has been based on simple association rather than a true causal link, they dispute the quality of epidemiological evidence in its favor. One of main criticism that has been raised concerns the paradoxically low gastric cancer rates found in some populations with high rates of infection (96, 97). Another arises from the low incidence of gastric cancer among patients with duodenal ulcer (98, 99), a disease known to be caused by H. pylori infection. Many hypothesis have been advanced to explain theses discrepancies. The virulence differences between various strains of H. pylori, genetic makeup of host, diet, immunological status ( ), and age (105 at the time of infection have all been proposed as factors potentially capable of influencing the outcome of H. pylori infection in different geographical area and in different individuals. From biological point of view, malignancy is known to be the results of an accumulation of genetic alterations and mutations that are responsible for the different phenotypes within the carcinogenic cascade. Up to now there has been no evidence that H. pylori directly 12

10 induces any sort of irreversible DNA damage. Disturbances in cell turnover in the gastrointestinal tract are believed to predispose to cancer development, and increased cell proliferation was considered to be a marker of increased gastric cancer risk(106,107). Recently cumulative evidence strongly suggest that H. pylori infection alters the kinetic pattern of gastric epithelium( ), The homeostasis of gastric epithelial cells is maintained by the balance between cell proliferation and apoptosis. Alterations of these physiological cellular events result in chronic pathological conditions of the stomach (121,122). An increase in the total number of epithelial proliferating cells and an abnormal distribution of the latter are frequently observed in chronic gastritis, gastric atrophy, intestinal metaplasia, gastric dysplasia and gastric cancer(113,114). Conversely, apoptosis has been found to be impaired in intestinal metaplasia, gastric dysplasia and cancer (123). Helicobacter pylori infection is associated with changes in epithelial-cell turnover. An increase in overall epithelial cell proliferation and the upward shift of replicating cells toward the superficial part of the gastric pits are patterns usually observed during Helicobacter pylori infection and these changes can be reversed by successful eradication of the infection ( ). However, it seems that this reversibility will be lost during progression through the steps of gastric carcinogenesis, such as intestinal metaplasia and dysplasia (113,114), probably representing the phenotypic expression of the true initiating phase of the carcinogenetic process. The influence of Helicobacter pylori infection on gastric epithelial apoptosis in humans is still controversial. Moss et al(l 16) reported that gastric epithelial apoptosis was clearly enhanced in duodenal ulcer patients with H. pylori infection, and this was later confirmed by others (117,118).But in some studies no such association was found (124). It seems that in vivo situation the status of H. pylori caga influences the effect of Helicobacter pylori on epithelial apoptosis. In patients infected with caga+ strains of H pylori gastric epithelial cell 13

11 proliferation was not accompanied by a parallel increase in apoptosis ( ). Increased cell proliferation in the absence of a corresponding increase in apoptosis may explain the heightened risk for gastric carcinoma. The mechanisms underlying the altered proliferation by H. pylori infection are thought to be caused by an increase in the mucosal content of ammonia, known to be a strong stimulus of cell proliferation (127,128), provoked by the bacterium itself. H. pylori infection associated hypergastrinemia is also believed to play a role in increasing epithelial cell turnover (129). Whether the hyperproliferation is also related to inflammatory infiltrate is controversial (130). As for the mechanisms involving the possible effects of H. pylori infection on gastric epithelial apoptosis, several recently finding may be relevant, including up-regulating expression of the CD95 (or apo-1 FAS) (131, 132,133), altered expression of bcl-2 family (134,135), immune activation and nitric oxide (136). H. pylori lipopolysaccharide as a virulence factor is responsible for the induction of gastric epithelial cell apoptosis (137). 14

12 REFERENCES 1. Warren JB, Marshall B. Unidentified curved bacilli on gastric epithelium in active chronic gastritis. Lancet 1983; I: Megraud F, Brassens-Rabbe M, Denis F, et al. Seroepidemiology of Campylobacter pylori infection in various populations. J Clin Microbiol 1989; 27: Dooley CP, Cohen H, Fitzgibbons PL, et al. Prevalence of Helicobacter pylori infection and histologic gastritis in asymptomatic persons. N Engl J Med 1989; 321 : Mitchell HM, Lee A, Berkowicz J, et al. The use of serology to diagnose active Campylobacter pylori infection. Med J Austral 1988;149: Ramirez-Ramos A, Leon-Banxa R, Gilman RH, et al. Helicobacter pylori and gastritis in Peruvian patients: relationship to socioeconomic level, age, and sex. Am J Gastroenterol 1990; 85: Graham DY, Malaty HM, Evans DG, et al. Epidemiology of Helicobacter pylori in an asymptomatic population in the United States. Effect of age, race, and socioeconomic status. Gastroenterology 1991; 100: Malaty HM, Kim JG, Kin SF, et al. Prevalence of Helicobacter pylori infection in Korean children: inverse relation to socioeconomic status despite a uniformly high prevalence in adults. Am J Epidemiol 1996; 143: Mitchell HM, Li YY, Hu PJ, et al. Epidemiology of Helicobacter pylori in southern China: identification of early childhood as the critical period for acquisition. J Infect Dis 1992;166: Li YY, Hu PJ, Du GG, et al. The prevalence of Helicobacter pylori infection in the Peoples Republic of China. Am J Gastroenterol 1991;86: Pan ZJ, Xiao SD, Jian S J, et al. Seroprevalence of Helicobacter pylori infection in urban and rural area of Shanghai. Chinese Journal of Digestion 15

13 1992;12: Malaty HM, Paykov V, Bykova O, et al. Helicobacter pylori and socioeconomic factors in Russia. Helicobacter 1996; 1: Handt LK, Fox JG, Dewhirst FE, et al. Helicobacter pylori isolated from the domestic cat: public health implications. Infect Immun 1994; 62: Baskerville A, and Newell DG. Naturally occurring chronic gastritis and C. pylori infection in the Rhesus monkey: a potential model for gastritis in man. Gut 1988; 29: Webb, PM, Kinght T, Elder JB, et al. Is Helicobacter pylori transmitted from cats to human? Helicobacter 1996;1: Berkowicz J, Lee A. Person-to-person transmission of Campylobacter pylori. Lancet 1987;2: Vincent P, Gottrand F, Pemes P, et al. High prevalence of Helicobacter pylori infection in cohabiting children. Epidemiology of a cluster, with special emphasis on molecular typing. Gut 1994; 35: Drumm B, Perez-Perez GI, Blaser MJ, et al. Intrafamilial clustering of Helicobacter pylori infection. N Engl J Med 1990; 322: Bamford KB, Kickley J, Collins JSA, et al. PCR identification of Helicobacter pylori in feces from gastritis patients. Lancet 1993;341: van der Ende A, Rauws EA, Feller M, et al. Heterogeneous Helicobacter pylori isolates from members of a family with a history of peptic ulcer disease. Gastroenterology 1996; 111: Miehlke S, Genta RM, Graham DY, et al. Molecular relationships of Helicobacter pylori strains in a family with gastroduodenal disease. Am J Gastroenterol 1999;94: Sahay P, Axon ATR. Reservoirs of Helicobacter pylori and mode of transmission. Helicobacter 1996;1:

14 22. Mapstone NP, Lynch DAF, Lewis FA, et al. PCR identification of Helicobacter pylori in feces from gastritis patients. Lancet 1993; 342: Thomas JE, Cibson GR, Darboe MK, et al. Isolation of Helicobacter pylori from human feces. Lancet 1993;340: Kelly SM, Pitcher MCL, Farmery SM, et al. Isolation of Helicobacter pylori from feces of patients with dyspepsia in the United Kingdom. Gastroenterology 1994;107: Krajden S, Fuksa M, Anderson J, et al. Examination of human stomach biopsies, saliva and dental plaque for Campylobacter pylori. Clin Microbiol. 1989;27: Ferguson DA, Li C, Patel NR, et al. Isolation of Helicobacter pylori from saliva. J Clin Microbiol 1993;31: Nguyen AH, Engstrand L, Genta RM, et al. Detection of Helicobacter pylori in dental plaque by reverse transcription-polymerase chain reaction. J Clin Microbiol 1993;31: Perez-Perez GI, Witkin SS, Decker MD, et al. Seroprevalence of Helicobacter pylori infection in couples. J Clin Microbiol 1991;29: Malaty HM, Evans DJ, Afranoritch K et al. Helicobacter pylori infection in dental workers: A seroepidemiolgy study. Am J Gastroenterol. 1992;87: Axon ATR. Review article: Is Helicobacter pylori transmitted by the gastro-oral route? Aliment. Pharmacol Ther 1995;9: Ramsey EJ, Carey KV, Peterson WL, et al. Epidemic gastritis with hypochlorhydria. Gastroenterology 1979;76: Gedhill T, Leicester RJ, Addis B, et al. Epidemic hypochlorhydria. BMJ 1985;76: Harford W, Bamett C,. Lee E, et al. Epidemic gastritis with hypochlorhydria: 10 17

15 year follow up [abstract]. Gastroenterology 1991;100:A Langenberg W, Rauws EAJ, Oudbier JH, et al. Patient-to-patient-transmission of Campylobacter pylori infection by fiberoptic gastroduodenoscopy and biopsy. J Infect Dis 1990;161: Tytgat GNJ. Endoscopic transmission of Helicobacter pylori. Aliment Pharmacol Ther 1995; 9:(Suppl 2): Mitchell HM, Lee A, Canick J. Increased incidence of Campylobacter pylori infection in gastroenterologists: Further evidence to support person-to-person transmission of C. pylori. Scand J Gastroenterol 1989;24: Lin SK, Lambert JR, Schembri MA, et al. H. pylori prevalence in endoscopy and medical staff. J Gastroenterol Hepatol 1994;9: Chong J, Marshall BJ, Barkin JS, McCallum RW, Reiner DK, Hoffman SR, et al. The occupational exposure to Helicobacter pylori for the endoscopy professional: a sera epidemiological study. Am J Gastroenterol 1994;89: Liu WZ, Xiao SD, Jiang SJ, et al. Seroprevalence of Helicobacter pylori infection in medical staff in Shanghai. Scand J Gastroenterol 1996;31: Potts LF, Lewis S J, Mountford RA. Prevalence of Helicobacter pylori in respiratory physician performing bronchoscopy: A comparison with gastroenterologists using the carbon 13 urea breath test. Helicobacter 1997; 2: NIH Consensus Development Panel. H. pylori in peptic ulcer disease. JAMA 1994;272: The European H. pylori Study Group. Current European concepts in management of H. pylori infection. The maastricht Consensus Report. Gut 1997; 41: Lam SK, Talley NJ. Report of the 1997 Asia pacific consensus conference on the management of H. pylori infection. J Gastroenterol Hepatol 1998;13: Marshall BJ. Helicobacter pylori. Am J Gastroenterol 1994;89(suppl):S116-18

16 S Haas CE, Nix DE, Schentag JJ. In vitro selection of resistant Helicobacter pylori. Antimicrob Agents and Chemother 1990;34: Rauws EAJ, Langenberg W, Houthoff HJ, et al. Campylobacter pyloridis - associated chronic active antral gastritis: A prospective study of its prevalence and the effects of antibacterial and antiulcer treatment. Gastroenterology 1988;94: Collins R, Beattie S, Xia HX, et al. Short report: high dose omeprazole and amoxicillin in the treatment of H pylori associated duodenal ulcer. Aliment Pharmacol Ther 1993;7: Noach LA, bertola MA, Schwartz MP, et al. Treatment of Helicobacter pylori infection: an evaluation of various therapeutic trials. Eur J Gastroenterol Hepatol 1994;6: Boer WAD, Tytgat GNJ. The best therapy for Helicobacter pylori infection: Should efficacy or side effect profile determine our choice. Scand J Gastroenterol 1995;30: Weissfeld AS, Simmon DE, Vance PH, et al. In vitro susceptibility of pretreatment isolates of Helicobacter pylori from two multicenter United State trials [abstract]. Gastroenterology 1996;110:A Noach LA, Langenberg WL, Bertola MA, et al. Impact of metronidazole resistance on the eradication of H. pylori. Scand J Infect Dis 1994;26: Ling TKW, Cheng AFB, Sung JJY, et al. An increase in Helicobacter pylori strains resistant to metronidazole: A five-year study. Helicobacter 1996; 1: Reddy R, Osato M, Gutierrez O, Kim JG, Graham DY. Metronidazole resistance is high in Korea and Colombia and appears to be rapidly increasing in the US. Gastroenterology 1996;110:A

17 54. Malanoski GJ, Eliopoulos GM, Ferraro MJ, et al. Effect of ph variation on the susceptibility of Helicobacter pylori to three macrolide antimicrobial agents and temafloxacin. Eur J Clin Microbiol Infect Dis 1993;12: Nagate T, Numata K, Hanada K, et al. The susceptibility of Campylobacter pylori to antiulcer agents and antibiotics. J Clin Gastroenterol 1990;12 (suppll): S135-S Peterson WL, Graham DY, Marshall B, et al. Clarithromycin as monotherapy for eradication of Helicobacter pylori :A randomized double-blind trial. Am J Gastroenterol 1993;88: Cayla R, Zerbib F, Talbi P, et al. Pre- and post-treatment clarithromycin resistance of H pylori strains: A key factor of treatment failure. Gut 1995;37(suppl2):A Xia HX, Buckley M, Hyde D, keane CT, O'Morain CA. Effects of antibioticresistance on clarithromycin-combined triple therapy for H pylori. Gut 1995;37 (suppl): A Zheng ZT, Wang ZY, Chu YX, et al. Double-blind short term trial of furazolidone in peptic ulcer. Lancet 1985: i: Zheng ZT, Wang YB. Treatment of peptic ulcer disease with furazolidone. J Gastroenterol. Hepatol. 1992;7: Morgan D, Kraft W, Bender M, Pearson A. Nitrofurans in the treatment of gastritis associated with Campylobacter pylori. The Gastrointestinal Physiology Working Group of Cayetano Heredia and The Johns Hopkins Universities. Gastroenterology 1988; 95: Xiao SD, Liu WZ, Xia DH, et al. The efficacy of furazolidone and metronidazole in the treatment of chronic gastritis associated with Helicobacter pylori-a randomized double-blind placebo-controlled clinic trial. Hepat-Gastroenterology 1990;37:

18 63. Segura AM, Gutierrez O, Otero W, et al. Furazolidone, amoxicillin, bismuth triple therapy for Helicobacter pylori infection. Aliment Pharmacol Ther 1997;11: Coelho LG, Passos MC, Chausson Y, et al. Five-day bismuth-free triple therapy for the eradication of Helicobacter pylori and reduction of duodenal ulcer relapse. Am J Gastroenterol 1991;86: Coelho LG, Passos MC, Chausson Y, et al. Duodenal ulcer and eradication of Helicobacter pylori in a developing country. An 18-month follow-up study. Scand J Gastroenterol 1992;27: Goodwin CS. Antimicrobial treatment of Helicobacter pylori infection. Clin Infect Dis 1997;25: Graham DY Klein PD, Opekum AR, et al. In vivo susceptibility of Campylobacter pylori. Am J Gastroenterol 1989; 84: Liu WZ, Shu Dong Xiao SD, Shi Y, et al. Furazolidone-containing short-term triple therapies are effective in the treatment of Helicobacter pylori infection Aliment Pharmacol Ther 1999;13: Xiao SD, Liu WZ, Hu PJ, et al. High cure rate of H. pylori infection using tripotassium dicitrato bismuthate, furazolidone and clarithromycin triple therapy for one week. Aliment Pharmacol Ther 1999; 13: Haas CE, Nix DE, Schentag JJ. In vitro selection of resistant H. pylori. Antimicrob Agents Chemother 1990;34: Marshall BJ,Armstrong JA,Francis GJ, et al. Antimicrobial action of bismuth in relation to Campylobacter pyloridis colonization and gastritis. Digestion 1987;37: Dra MA, Deegan P, Leen E, et al. The effect of omeprazole on Helicobacter pylori and associated gastritis. Aliment Pharmacol Ther 1991;5: Iwahi T, Satoh H, Nako M, et al. Lansoprazole, a novel benzimidazole proton 21

19 pump inhibitor, and its related compounds have selective activity against H. pylori. Antimicrob Agents Chemother 1991;35: Gustavson LE, Kaiser JE, Edmonds AL, et al. Effect of omeprazole on concentration of clarithromycin in plasma and gastric tissue at steady state. Antimicrob Agents Chemother 1995;39: Goddard AF, Jessa MJ, Barrett DA, et al. Effect of omeprazole on the distribution of metronidazole, amoxicillin and clarithromycin in human gastric juice. Gastroenterology 1996:111: Lind T, Veldhuyzen van Zanten S, Unge P, et al. Eradication of Helicobacter pylori using one-week triple therapies combining omeprazole with two antimicrobials: the MACH1 study. Helicobacter 1996:1: Lind T, Megraud F, Unge P, et al. The MACH2 study: role of omeprazole in eradication of Helicobacter pylori with 1-week triple therapies. Gastroenterology 1999; 116: Hentschet E, Brandstatte G, Dragosics, et al. Effect of ranitidine and amoxicillin plus metronidazole on the eradication of Helicobacter pylori and the recurrence of duodenal ulcer. N Engl J Med 1993;328: Bardhan KD, dallaire C, Eisold H, et al. Ranitidine bismuth citrate with clarithromycin for the treatment of duodenal ulcer. Gut 1997;41: Ponder RE, Wyet JW, Duggan AE, et al. Ranitidine bismuth citrate with clarithromycin for the eradication of Helicobacter pylori and for ulcer healing. Helicobacter 1997;2: Labenz J, Oyenes E, Ruhl CH, et al. Omeprazole plus amoxicillin: Efficacy of various treatment regiments to eradicate Helicobacter pylori. Am J Gastroenterol. 1993;88: Bayerdorffer E, Miehlke S, Mannes GA, et al. Double-blind trial of omeprazole and amoxicillin to cure Helicobacter pylori in patients with duodenal ulcers. 22

20 Gastroenterology 1995;108: Laine L, Stein C, Neil G. Limited efficacy of omeprazole-based dual and triple therapy for Helicobacter pylori: A randomized trial employing "optimal' dosing. Am J Gastroenterol 1995; 90: Garaham KS, Malaty HM, El-Zimaity. HMT, et al. Variability with omeprazoleamoxicillin combinations for treatment of Helicobacter pylori infection. Am J Gastroenterol. 1995;90: van der Hulst RWM, Weel JFL, Verheul SB, et al. Treatment of Helicobacter pylori infection with low or high dose omeprazole combined with amoxicillin and the effect of retreatment: A prospective, randomized, double-blind study. Aliment Pharmacol Ther 1996;10: Chiba N, WilkiosonJ, Hunt RH, et al. Omeprazole and clarithromycin in Helicobacter pylori eradication: A meta-analysis [abstract]. Gastroenteroloy 1996;110:A Peterson WL, CiociolaAA, Sykes DL, et al. Ranitidine bismuth citrate plus clarithromycin is effective for healing duodenal ulcer, eradicating H. pylori and reducing ulcer recurrence. Aliment Pharmacol Ther 1996;10: Gisbert JP, Pajares JM, Valle J. Ranitidine bismuth citrate therapy regimens for treatment of Helicobacter pylori infection: A review. Helicobacter 1999;4: Tatgat GNJ. Review article: Treatment that impact favorable upon the eradication of Helicobacter pylori and ulcer recurrence. Aliment Pharmacol Ther 1994;8: Pentson, J. G. Review article: Helicobacter pylori eradication-understandable caution at no excuse for inertia. Aliment. Pharmacol Ther 1994;8: Bazzoli F, Zagari RM, Fossi S, et al. Short term low-dose triple therapy for eradication of Helicobacter pylori. Eur J Gastroenterol Hepatol 1994;6:773-23

21 Hetzel DJ, Dekkers C, Coremans G, et al. Ranitidine bismuth citrate with low dose clarithromycin and metronidazole twice daily for one week gives high rates ofhelicobacter pylori eradication [abstract]. Gut 1997;41(suppl 3):A de Boer WA, Driessen WM, Jansz AR, et al. Effect of acid suppression on efficacy of treatment for Helicobacter pylori infection. Lancet 1995; de Boer WA, Driessen WM, Jansz AR, et al. Quadruple therapy compared with dual therapy for eradication of Helicobacter pylori in ulcer patients: results of a randomized prospective single-centre study. Eur J Gastroenterol Hepatol 1995;7: International Agency for Research on Cancer. I ARC Monographs on the evaluation of carcinogenic risks to humans. Vol 61. Schistosomes, liver flukes and Helicobacter pylori. Lyon: Goldstone ARQuirker P, Dixon MR Helicobacter pylori infection and gastric cancer. J Pathol 1996;179: Hu PJ, Li YY, Zhou MH, et al. Helicobacter pylori associated with a high prevalence of duodenal ulcer disease and a low prevalence of gastric cancer in a developing nation. Gut 1995;36: Lee S, Iida M, Yao T, et al. Risk of gastric cancer in patient with nonsurgical treated peptic ulcer. Scand J Gastroenterol 1990;25: Lewis JH, Woode M. Gastric carcinoma in patients with unoperated duodenal ulcer disease. Am J Gastroenterol 1982;77: Atherton JC, Peek RM, Jr, Tham KT, et al. Clinical and pathological importance of heterogeneity in vaca, the vacuolating cytotoxin gene of Helicobacter pylori. Gastroenterology, 1997, 112: Censini S, Lange C, Xiang ZY, et al. Cag, a pathogenicity island of Helicobacter pylori, encodes type I specific and disease associated virulence factors. Proc Natl 24

22 Acad Sei, 1996, 93: Azuma T, Ito S, Sato F, Yamazaki Y, et al. The role of the HLA-DQAlgene in resistance to atrophic gastritis and gastric adenocarcinoma induced by Helicobacter pylori infection. Cancer, 1998, 82: Ernst P. The role of inflammation in the pathogenesis of gastric cancer. Aliment Pharmacol Ther, 1999, 13(suppl l): Faller G, Steininger H, Appelmelk B, et al. Evidence of novel pathogenic pathways for the formation of antigastric autoantibodies in Helicobacter pylori gastritis. J Clin Pathol, 1998, 51: Blaser MJ, Chyou PH, Nomura A. Age at establishment of Helicobacter pylori infection and gastric carcinoma, gastric ulcer, and duodenal ulcer risk. Cancer Res 1995;55: Yong-ling X, Zhi-tian Z. Cell proliferation kinetics in chronic gastritis and gastric cancer. Chin Med J 1984;97: Biasco G, Paganelli GM, Santucci R, et al. Cell proliferation kinetics as a marker of gastric cancer risk. Ital J Gastroenterol 1991 ;23: Brenes F, Ruiz B, Correa P, et al. Helicobacter pylori causes hyperproliferation of gastric epithelium: pre and post-eradication indices of proliferating cell nuclear antigen. Am J Gastroenterol 1993;88: Fraser AG, Sim R, Sankey EA, et al. Effect of eradication of Helicobacter pylori on gastric epithelial cell proliferation. Aliment Pharmacol Ther 1994;8: Fan XG, Kelleher D, Fan XJ, et al. Helicobacter pylori increases proliferation of gastric epithelial cell. Gut 1996;38: Cahill RJ, Xia H, Kilgallen C, et al. Effect of eradication of Helicobacter pylori infection on gastric epithelial cell proliferation. Dig Dis Sei 1995;40: Lynch DA, Mapstone NP, Clarke AM, et al. Cell proliferation in Helicobacter 25

23 pylori associated gastritis and the effect of eradication therapy. Gut 1995; 36: Cahill RJ, Kilgallen C, Beattie S, et al. Gastric epithelial cell kinetics in progression from normal mucosa to gastric carcinoma. Gut 1996;38: Panella C, Ierarddi E, Polimeno L, et al. Proliferative activity of gastric epithelium in progressive stages of Helicobacter pylori infection. Dig Dis Sei 1996;41: Murakami K, Fujioka T, Kodama R, et al. Helicobacter pylori infection accelerates human gastric mucosal cell proliferation. J Gastroenterol 1997; 32: Moss SF, Calam J, Agarwal B, et al. Induction of gastric epithelial apoptosis by Helicobacter pylori. Gut 1996; 38: Dong QJ, Liu WZ, Zheng X, et al. Effect of Helicobacter pylori infection on gastric epithelial apoptosis. Chin J Gastroenterol 1996; 1: Jones NL, Yeger H, Cutz E, et al. Helicobacter pylori induces apoptosis of gastric epithelial cells in vivo [abstract]. Gastroenterology 1996;110(suppl): A Wagner S, Beil W, Westermann J, et al. Regulation of gastric epithelial cell growth by Helicobacter pylori: evidence for a major role of apoptosis. Gastroenterology 1997; 113: Jones NL, Shannon PT, Cutz E, et al. Increase in proliferation and apoptosis of gastric epithelial cells early in the natural history of Helicobacter pylori infection. Am J Pathol 1997; 151: Watson AJM. Necrosis and apoptosis in gastrointestinal tract. Gut 1995;37: Que FG and Gores GJ. Cell death by apoptosis: Basic concepts and disease relevance for the gastroenterologist. Gastroenterology 1996;110:

24 123. Liu WZ, Dong QJ, Zheng X, et al. Effect of Helicobacter pylori infection on apoptosis of gastric precancerous lesions. Journal of Weifang Medical College 1997; 19: (in Chinese) Peek RM Jr, Moss SF, Tham KT et al. Helicobacter pylori caga+ strains and dissociation of gastric epithelial cell proliferation from apoptosis. J Natl Cancer Inst 1997; 89: Li H, Mellgârd B, Heiander HF. Inoculation of VacA- and CagA- Helicobacter pylori delays gastric ulcer healing in the rat. Scand J Gastroenterol 1997; 32: Rokkas T, Ladas S, Liatsos C, et al. Relationship of Helicobacter pylori CagA status to gastric cell proliferation and apoptosis. Dig Dis Sei 1999; 44: Tsujii M, Kawano S, Tsujii S et al. Cell kinetics of mucosal atrophy in rat stomach induced by long-term administration of ammonia. Gastroenterology 1993;104: Tsujii M, Kawano S, Tsuj S, et al. Mechanism for ammonia-induced promotion of gastric carcinogenesis in rats. Carcinogenesis 1995;16: Axon ATR. Helicobacter pylori. In Pounder R, ed. Recent advances in Gastroenterology. London: Churchill Liveingstone, 1992: Lynch DAF, Axon ATR. Helicobacter pylori, gastric cancer and gastric epithelial kinetics: a review. Eur J Gastroenterol Hepatol 1995;(suppl l):s Fan XJ, Crowe SE, Bamford KB, et al. Fas-mediated apoptosis of gastric epithelial cells [abstract]. Gastroenterology 1997;112(suppl):A Rudi J, Kuck D, Strand S, et al. Involvement of the CD95 (APO-1/Fas) receptor and ligand system in Helicobacter y/ow-induced gastric epithelial apoptosis. J Clin Invest 1998;102: Houghton J, Korah RM, Condon MR, et al. Apoptosis in Helicobacter pyloriassociated gastric and duodenal ulcer disease is mediated via the Fas antigen 27

25 pathway. Dig Dis Sei 1999;44: Chen G, Hansely Z, Ramey W, et al. Apoptosis of in gastric epithelial cells induced by H. pylori is accompanied by altered expression of the Bcl-2 protein family [abstract]. Gut 1997; 41(suppl 1):A Chen G, Sordillo EM, Ramey WG, et al. Apoptosis in gastric epithelial cells is induced by Helicobacter pylori and accompanied by increased expression of BAK. Biochem Biophys Res Commun 1997;239: Mannick EE, Bravo LE, Zarama G, et al. Inducible nitric oxide synthase, nitrotyrosine, and apoptosis in Helicobacter pylori gastritis: effect of antibiotics and antioxidants. Cancer Res 1996; 56: Piotrowski J, Piotrowski E, Skrodzka D, et al. Induction of acute gastritis and epithelial apoptosis by Helicobacter pylori lipopolysaccharide. Scand J Gastroenterol 1997; 32:

26 Outline of This Thesis Since successful isolation of H. pylori from the human stomach by Warren and Marshall in 1983, the study of this microorganism has gained significant impetus. A great deal of research has been done and astonishing amount of papers has appeared in the world literatures over past decade. These research and papers cover a broad spectrum of issues varying from epidemiology, detection of the infection, its relation to gastritis, peptic ulcer disease and gastric malignancies, its virulence factors, its role in disturbance of gastric homeostasis and therapy. Despite this unrivaled scientific exploring and research, many questions remain unsolved. The aim of this thesis is to contribute to the knowledge of : 1. the risk of H. pylori infection in medical staff in area with high infection rates; 2. the role of furazolidone and new non-metronidazole triple regimens in anti-//, pylori therapy; 3. the effects of H. pylori infection on gastric epithelial cell turnover. In chapter 2 the issue whether medical staff, especially endoscopy unit personnel, are at increased risk of infection with H. pylori is investigated. Previous reports of the seroprevalence of H. pylori in endoscopy staff have yielded conflicting results. The risk of H. pylori infection was evaluated through the comparisons of seroprevalence of H. pylori infection between a large group of medical staff and healthy controls with stratification of age. In chapter 3 the efficacy of furazolidone against H. pylori is explored in vitro and in vivo. Furazolidone a nitrofuran in clinical use for over 30 years, was used in China for the treatment of peptic ulcer disease long before H. pylori was discovered as an etiological agent in this disease. The anti-ulcer role of furazolidone might be explained 29

27 by its anti-//: pylori action. In a randomized double-blind placebo-controlled clinical trial the efficacy of furazolidone as monotherapy for anti-//, pylori was assessed and in vitro sensitivity test with MICs for H. pylori was determined. In chapter 4 efficacious furazolidone-containing triple therapies for H. pylori have been explored. Furazolidone has been proved highly efficacious against H. pylori, and resistance of H. pylori to it is not easily emerged. A furazolidone-containing therapeutic regimen for H. pylori infection has attracted special interest in the face of a world-wide rising resistance of K.pylori to metronidazole. In the present study we use furazolidone and clarithromycin in combination with either colloidal bismuth subcitrate (CBS), also called tripotassium dicitrato bismuthate (TDB) or a proton pump inhibitor to evaluate the efficacy of furazolidone as a replacement for metronidazole in standard "triple therapy " regimens currently advocated to eradicate H. pylori. In chapter 5 the efficacy of non-metronidazole bismuth-based triple therapies for H. pylori infection was evaluated. Resistance strains of// pylori to metronidazole, a key antibiotic agent of anti-//, pylori therapy are increasing in frequency worldwide, such resistance will limit the usefulness of metronidazole-containing regimens. This concern has prompted the search for effective, inexpensive, non-metronidazole therapies. Three bismuth-based, non-metronidazole triple regimens were investigated. The therapy consisting of TDB, clarithromycin and furazolidone provides a satisfactory result, and the combination of TDB, josamycin and furazolidone achieved sub-optimal result. In chapter 6, 7 and 8 effects of H. pylori infection on gastric epithelial cell turnover, including cell proliferation and apoptosis, were studied. Chapter 6 elaborates on the effect of//, pylori infection on gastric epithelial apoptosis by comparisons between //. #y/orz-associated chronic gastritis and H. pylori negative normal controls and between 30

28 pre- and post-eradication therapy. H. pylori infection appears to induce gastric epithelial apoptosis in patients with chronic gastritis. In chapter 7 the effect of H. pylori infection on apoptosis of gastric precancerous lesions was investigated. The apoptosis in gastric precancerous lesions is reduced, H. pylori infection apparently has no effect on apoptosis in these lesions. In chapter 8 the effect of H. pylori infection on gastric epithelial proliferation in progression from normal mucosa to gastric carcinoma is studied. H. pylori infection causes increased gastric epithelial cell proliferation in the stages of superficial and mild atrophic gastritis, and may play a part in triggering gastric carcinogenesis. 31

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