Prevention of water immersion stress-induced gastric lesions through the enhancement of nitric oxide synthase activity in rats

Efficacy of triple therapy plus cetraxate for the Helicobacter pylori eradication in partial gastrectomy patients

In the present study, we aimed to establish an additional standardized protocol with a higher H. pylori eradication rate in the remnant stomach. Fifty-five H. pylori-positive patients were randomly allocated to one of three regimens: LAC--lansoprazole, amoxicillin, and clarithromycin b.i.d. for 7 days (n = 17); LAC+CET--LAC b.i.d. plus cetraxate q.i.d. for 7 days (n = 20); and LEFT--LAC for 7 days in a horizontal body position on the left side for 30 min (n = 18). Patient compliance and side effects were checked via interviews. H. pylori eradication was successful in 75, 72, and 41% in LAC+CET, LEFT, and LAC, respectively. The eradication rate was significantly higher in LAC+CET than in LAC (P = 0.024) but not in LEFT (P = 0.058). Adverse events that occurred in each group were almost all mild ones. Cetraxate plus LAC for 1 week is a safe and effective regime for the eradication of H. pylori in patients after partial gastrectomy.

DA-9601 for erosive gastritis: Results of a double-blind placebo-controlled phase III clinical trial

AIM: To determine the efficacy and safety of DA-9601 on erosive gastritis versus cetraxate as a standard drug by gastrointestinal endoscopy.

METHODS: Five hundred and twelve patients with erosive gastritis were divided into three groups. The groups received 180 mg or 360 mg of DA-9601, or 600 mg of cetraxate (Neuer^TM) t.i.d. for 2 wk, respectively. Endoscopic observations were performed before and 2 wk after the treatment, and the cure and improvement rates were investigated.

RESULTS: Of the 512 intention-to-treat (ITT) population, 457 patients comprised the per protocol (PP) analysis. Endoscopic cure rate was significantly higher in the DA-9601 group than in the cetraxate group in both the PP (56%, 58% vs 36%; DA-9601 180 mg, 360 mg and cetraxate, respectively) and ITT (52%, 51% vs 35%) populations. Two DA-9601 groups (180 and 360 mg) had significantly higher endoscopic improvement rates than the cetraxate group in both the PP (67%, 65% vs 46%) and ITT (63%, 58% vs 45%) populations. The percentage of symptom relief over the 2 wk was found not significantly different between groups. During the study, both DA-9601 and cetraxate produced no treatment-associated adverse events.

CONCLUSION: From these results, it appears that DA-9601 has excellent efficacy on erosive gastritis. This study also confirms the safety profile of DA-9601.

Of blood and guts: association between Helicobacter pylori and the gastric microcirculation

The relative importance of acid in Helicobacter pylori (H. pylori) ulcer pathogenesis is in doubt, with possibilities existing that other contributing factors may be involved. Vascular insufficiency may lead to the development of ischemic lesions or ulcers within the gastric mucosa. H. pylori produces a striking inflammatory response following infection and one of the major components of gastrointestinal inflammation is alterations in the vascular structure and function. This suggests that the microcirculation may be a key target of H. pylori-released factors. Recent evidence has accumulated to suggest that H. pylori can affect a number of microcirculatory variables including blood flow, leukocyte activity and also induce changes in the endothelial lining of the vessels themselves. The majority of these findings have been described by employing the technique of fluorescent in vivo microscopy, which allows direct, dynamic and real time observations of the microcirculation to be made. A universal feature of these experimental studies has been the formation of circulating or adherent platelet aggregates. It is now recognized that platelets participate in the inflammatory response by acting as a potent source of inflammatory mediators and modulating the activity of other inflammatory cells. Circulation of platelet emboli may be of cause for concern, especially as a number of studies have demonstrated an association between H. pylori infection and coronary heart disease. The present review highlights the major findings from these studies and proposes an important role for the gastric microcirculation in the pathophysiology of H. pylori-induced injury.

[An overview of acetic acid ulcer models and their utility for drug screening]

Since Takagi et al. reported an experimental chronic gastric ulcer model [acetic acid ulcers induced by submucosal injection of acetic acid (Type 1)], we further modified the methodology and subsequently devised three more models. The second model involves inducing ulcers by serosal application of an acetic acid solution (Type 2) and the third model achieves ulcer induction by intragastric application of an acetic acid solution (Type 3). The forth model was modification of the third model by giving the acetic acid solution and the same volume of air to make one ulcer in the stomach (Type 4). In general, animals accepted the procedures without problems and no undesirable effects were noticed. More importantly, this experimental animal model allows production of ulcers that highly resemble human ulcers in terms of both pathology and healing. Indeed, relapse is even endoscopically observed for 360 days after ulceration. The ulcers produced not only respond well to various anti-ulcer medications, such as antisecretory and mucosal protective drugs and growth factors, but also demonstrate appropriate responses to ulcerogenic agents such as NSAIDs. In addition, we have recently demonstrated that H. pylori infection resulted in delayed ulcer healing and recurrence of healed acetic acid ulcers induced in Mongolian gerbils. The present article gives a brief summary of the ulcer history before establishment of acetic acid ulcers and characteristic features of acetic acid ulcer, including both their merits and shortcomings.

Influence of Helicobacter pylori infection and cetraxate on gastric mucosal blood flow during healing of endoscopic mucosal resection-induced ulcers

BACKGROUND AND AIM

Helicobacter pylori (H. pylori) infection is known to affect the gastric microcirculation, and cetraxate is reported to accelerate gastric ulcer healing, possibly by augmenting gastric mucosal blood flow (MBF). The aim of this study is to clarify the effect of H. pylori infection and cetraxate on MBF during gastric ulcer healing.

METHODS

Forty-two patients who had undergone endoscopic mucosal resection (EMR) were studied. Mucosal blood flow was measured by the use of a laser Doppler flowmeter in the surrounding mucosa and at the ulcer margin, before, 1 day, 1 week and 4 weeks after EMR. Helicobacter pylori infection was confirmed by the use of bacterial culture and histology. After EMR, patients were randomly assigned to receive 30 mg lansoprazole (u.i.d; L-regimen) or 30 mg lansoprazole (u.i.d.) with 200 mg cetraxate (q.i.d; LC-regimen) for 4 weeks.

RESULTS

The MBF ratio (MBF at ulcer margin/MBF in surrounding mucosa) 1 week after EMR was significantly lower than that before or 4 weeks after EMR only in H. pylori-positive patients treated with the L-regimen. No such decrease in MBF was observed after 1 week in H. pylori-positive patients treated with the LC-regimen or in H. pylori-negative patients.

CONCLUSION

A transient decrease in MBF was detected at the ulcer margin during healing of EMR-induced ulcers in H. pylori-infected patients. Cetraxate seemed to prevent this decrease in MBF.

Nitric oxide: relation to integrity, injury, and healing of the gastric mucosa

Nitric oxide (NO) plays a multifaceted role in mucosal integrity. The numerous functions of NO and the double-edged role played by NO in most of them provide a great complexity to the NO action. The three enzymatic sources of NO, neuronal NO-synthase (nNOS), endothelial NOS (eNOS), and inducible NOS (iNOS), have been characterised in the gastrointestinal tract. The protective properties of the NO derived from constitutive NO-synthases (eNOS and nNOS) have already been well established. Less clear is the role assigned to iNOS. The simplistic initial view of low levels of NO synthesised by constitutive NOS being protective while exaggerated NO levels after iNOS induction leading irremediably to cytotoxicity is being questioned by new evidence. As initially reported for constitutive NOS, iNOS activity may be associated to reduced leukocyte-endothelium interaction and platelet aggregation as well as protection of mucosal microcirculation. Moreover, iNOS activity may be important to resolve inflammation by increasing apoptosis in inflammatory cells. It is entirely possible that a low level of expression of iNOS will reflect a positive host-defense response to challenge, but that exaggerated or uncontrolled expression of iNOS itself becomes detrimental. There is no doubt about the protective role of NO in physiological conditions. However, when the mucosa is threatened, the role of NO becomes multiple and the final effect will probably depend on the nature of the insult, the environment involved, and the interaction with other mediators.

Exacerbatory mechanism responsible for water immersion stress-induced gastric lesions in aged rats compared with young rats

1. The present study was designed to investigate whether or not ageing affects the development of water immersion stress-induced gastric lesions in rats. Effects of cetraxate, an anti-ulcer drug, were also examined. 2. Gastric lesions were induced by 6 h water immersion stress in rats. Gastric mucosal blood flow was determined by the hydrogen gas clearance technique and nitric oxide synthase (NOS) activity was measured enzymatically. 3. Early development of gastric lesions was observed in aged rats and exacerbation of gastric lesions was also found. Lowering of gastric mucosal blood flow and reduced NOS activity were observed in aged rats. 4. Cetraxate mitigated the development of gastric lesions in young rats and also increased gastric mucosal blood flow and NOS activity. However, these favourable effects were diminished in aged rats. 5. Decreased NOS activity may be an important exacerbatory factor to the development of gastric lesions in aged rats. 6. Effects of cetraxate differed between young rats and aged rats. 7. These results may explain the refractoriness and drug resistance in gastric ulcers encountered by elderly individuals.

Gastric mucosal integrity: gastric mucosal blood flow and microcirculation. An overview

The stomach is in a state of continuous exposure to potentially hazardous agents. Hydrochloric acid together with pepsin constitutes a major and serious threat to the gastric mucosa. Reflux of alkaline duodenal contents containing bile and pancreatic enzymes are additional important injurious factors of endogenous origin. Alcohol, cigarette smoking, drugs and particularly aspirin and aspirin-like drugs, and steroids are among exogenous mucosal irritants that can inflict mucosal injury. The ability of the stomach to defend itself against these noxious agents has been ascribed to a number of factors constituting the gastric mucosal defense. These include mucus and bicarbonate secreted by surface epithelial cells, prostaglandins, sulfhydryl compounds and gastric mucosal blood flow. The latter is considered by several researchers to be of paramount importance in maintaining gastric mucosal integrity. The aim of this paper is to review the experimental and clinical data dealing with the role of mucosal blood flow and in particular the microcirculation in both damage and protection of the gastric mucosa.

Role of nitric oxide synthase inhibitor in experimental colitis induced by 2,4,6-trinitrobenzene sulphonic acid in rats

1. The present study was designed to investigate the role of nitric oxide (NO) in modulating 2,4,6-trinitrobenzene sulphonic acid (TNBS)-induced colitis in rats. 2. Damage scores and NO synthase (NOS) activity were measured. 3. The damage scores and NOS activity reached a peak on the 4th day after administration of TNBS solution (day 0), thereafter gradually decreasing, and were significantly higher than in the group treated with saline throughout the experimental period. 4. Subsequently, we divided the stage of colitis into two groups, one from day 0 to day 3 after induction of colitis, and the other from day 4 onwards. We evaluated the effects of the NOS inhibitor N(G)-monomethyl-L-arginine (L-NMMA), on TNBS-hapten-induced colitis and colonic mucosal blood flow. Two different methods of L-NMMA administration, from day 0 to day 3, and from day 4 onwards, were undertaken. 5. The damage score in the early L-NMMA treatment group was significantly higher than in the group without L-NMMA on day 14. In contrast, the damage score in the late L-NMMA treatment group was not significantly different from the group without L-NMMA. Colonic mucosal blood flow in the early L-NMMA treatment group was not significantly different from that in the late L-NMMA treatment group. 6. These data suggest that NO is important for inhibiting inflammation during the early stages.

Cetraxate, a mucosal protective agent, combined with omeprazole, amoxycillin, and clarithromycin increases the eradication rate of helicobacter pylori in smokers

BACKGROUND

Our previous study demonstrated that Helicobacter pylori eradication was less effective in smokers than in non-smokers. Cetraxate is an anti-ulcer drug that increases gastric mucosal blood flow.

AIM

To evaluate the effect of cetraxate combined with new triple therapy for the eradication of H. pylori in smokers.

METHODS

This study had a single-centre, double-blind, randomized non-placebo design. A total of 106 consecutive H. pylori-positive smoking patients were randomly allocated to one of two regimens: one group received omeprazole (20 mg), amoxycillin (1500 mg), and clarithromycin (600 mg) for 7 days (OAC, n=55). The other group recieved OAC plus cetraxate (600 mg) for 7 days (OAC + CET, n=51). The success of H. pylori eradication was evaluated by histology and the 13C-urea breath test at 4 weeks after completion of treatment.

RESULTS

By intention-to-treat analysis, the H. pylori eradication rate was 55% in the OAC group and 92% in the OAC + CET group (P<0.01). By per protocol analysis, the H. pylori eradication rate was 58% in the OAC group and 94% in the OAC + CET group (P<0.01).

CONCLUSION

Cetraxate combined with new triple therapy increases the eradication of H. pylori in smokers.

Mediators of stress effects in inflammatory bowel disease: not the usual suspects

Empirical efforts to prove or disprove an association between stress and the course of inflammatory bowel disease (IBD) have had inconsistent results. Direct study of mediators of stress-related physiological processes may clarify this important area.

METHODS

candidate mediators were selected based on evidence that they have a role in the pathophysiology of IBD. Medline searches for original articles addressing each putative mediator and psychological stress were conducted. Articles were reviewed with goals of synthesis and hypothesis generation.

RESULTS

there is evidence that substance P (SP), vasoactive intestinal protein (VIP), tumour necrosis factor alpha (TNFalpha), oxidant molecules, endogenous glucocorticoids and heat shock proteins (HSPs) are involved in the stress response.

DISCUSSION

two principles emerge which should inform efforts to investigate stress in IBD. First, stress effects are regulated by highly interdependent systems. Second, the effects of mediators are highly specific to the location of their activity, and so, investigations in IBD are likely to require direct investigation of inflamed and unaffected gut tissue.

Direct measurement of nitric oxide release in gastric mucosa during ischemia-reperfusion in rats

Nitric oxide (NO) generation in the rat gastric mucosa during ischemia-reperfusion was measured using an NO-sensitive electrode. Under pentobarbital sodium anesthesia, an electrode was inserted into the submucosa from the serous membrane side in the fundus. After steady-state baseline recording, the celiac artery was clamped for 30 min, and then ischemia-reperfusion was achieved by removing the clamp. The clamping of the celiac artery caused a decrease in blood flow and an increase in NO level in the gastric tissue. Just after the removal of the clamp, the NO level rapidly fell and returned to the baseline level. Administration of NG-nitro-L-arginine methyl ester (an NO synthase inhibitor, 30 mg/kg i.p.) before ischemia significantly attenuated both the increase in NO level during ischemia and the formation of acute gastric mucosal lesions observed after 60 min reperfusion. Administration of superoxide dismutase (a superoxide radical scavenger, 10,000 U/kg i.v.) at the end of ischemia inhibited both the rapid decrease in NO level during the reperfusion and the gastric mucosal erosions. Because NO and superoxide radical produce a highly reactive peroxynitrite, it can be argued that NO has an important pathological role in acute gastric mucosal injury induced by ischemia-reperfusion. Our conclusion was strongly supported by immunohistochemical staining of nitrotyrosine residues, an indication of peroxynitrite formation.