Effect of cigarette smoking on the gastric mucosal blood volume index and hemoglobin oxygenation in man

Risk factors for gastrointestinal complications in aspirin users: review of clinical and experimental data

This paper reviews recent clinical evidence that suggests that aspirin prophylaxis against cardiac and cerebral vascular ischemia is associated with significant gastrointestinal complications. The clinical and experimental evidence to confirm the role of risk factors of concomitant use of nonsteroidal anti-inflammatory drugs (NSAID), tobacco cigarette smoking, and alcohol consumption are discussed. The limitations of long-term acid suppression treatment for the prevention of these complications are considered. Future experimental studies to guide the clinical approach to develop novel and potentially cost-effective management strategies are discussed.

Endoscopic reflectance spectrophotometry and visible light spectroscopy in clinical gastrointestinal studies

The use of reflectance spectrophotometry (RS) for mucosal hemodynamic measurement relies on the recognition of changes in indexes of mucosal hemoglobin concentration and oxygen saturation. Endoscopic application in clinical studies has confirmed important observations demonstrated in animal experiments. The vasoconstriction induced by propranolol, vasopressin, glypressin, or somatostatin in the portal hypertensive gastric mucosa and the reduction of gastroduodenal mucosal perfusion by nonsteroidal anti-inflammatory drugs (NSAIDs) or smoking, mesenteric venoconstriction associated with systemic hypoxia, and acid-induced duodenal hyperemia are important examples. Prognostic predictions include the development of stress-induced gastric ulcerations in patients with significant reductions in gastric perfusion after thermal or head injury, or the demonstration of delayed gastric or duodenal ulcer healing when the hyperemia at the ulcer margin fails to materialize. In mechanical-ventilator-dependent patients with sepsis, a significantly reduced gastric mucosal RS measurement portends a grave prognosis (mortality >80%). Recent advances in technology resulted in the construction and validation of instruments for visible light spectroscopy. Measurements focused on tissue oxygen saturation demonstrated epinephrine and vessel-ligation-induced vasoconstriction, the absence of ischemia in radiation-induced rectal telangiectasias, and gut ischemia responsive to revascularization treatment. Endoscopic RS and visible light spectroscopy are suitable for assessing the role of blood flow in conditions with a lesser degree of ischemia and for testing the hypothesis that functional dyspepsia and dysmotility syndromes may be due to gut ischemia.

Relationship between Helicobacter pylori infection and smoking and drinking habits

BACKGROUND

Helicobacter pylori is a major cause of various gastroduodenal diseases. Some risk factors related to H. pylori infection have been reported; however, studies on the relationship between H. pylori infection and smoking or drinking habits have given conflicting results. In the present study, these relationships were investigated by collecting sera and information from 8837 subjects.

METHODS

Serum H. pylori immunoglobulin G antibody was measured by an enzyme-linked immunoassay. In addition to sex and age, information on smoking and drinking habits was collected by questionnaire. Age- and sex-adjusted odds ratios (95% confidence interval) of smoking and alcohol consumption were calculated for H. pylori seropositivity using logistic regression models.

RESULTS

Current smokers had a 0.82 (0.74-0.91)-fold greater risk of H. pylori seropositivity than those who had never smoked. Current cigarette consumption showed a dose-dependently negative association with H. pylori seropositivity, and the association between smoking and H. pylori infection was strong in younger subjects. Current drinkers had a 0.88 (0.79-0.98)-fold greater risk of H. pylori seropositivity than those who had never drunk alcohol. The volume of alcohol consumed showed a negative association with H. pylori seropositivity.

CONCLUSIONS

In the current study, smoking was negatively associated with H. pylori infection. The risk of H. pylori seropositivity decreased linearly with cigarette consumption per day. Increased gastric acidity in the stomach through smoking may be a cause of the dose-dependently negative association between H. pylori and smoking. Drinking was negatively and dose-dependently associated with H. pylori positivity, although the effect of drinking was weaker than that of smoking.

Misoprostol reverses the inhibition of gastric hyperemia and aggravation of gastric damage by tobacco cigarette smoke in the rat

BACKGROUND

Tobacco cigarette smoke attenuates injury-induced hyperemia, aggravates hypertonic saline-induced mucosal damage, inhibits ulcer margin hyperemia, and increases the size of the acetic acid-induced ulcer in the rat stomach. The inhibitory effect of tobacco cigarette smoke on gastric prostaglandin metabolism may be the basis for these observations. We have tested the hypothesis that exogenous prostaglandin (misoprostol) treatment will reverse these effects.

METHODS

Rats with these two types of gastric injury were treated with tobacco cigarette smoke or breathed room air and were given intragastric misoprostol or vehicle. Gastric mucosal blood flow was measured by hydrogen gas clearance, and lesion score or ulcer size was measured by image analysis.

RESULTS

Tobacco cigarette smoke attenuated the hyperemia and significantly aggravated the mucosal lesions and increased ulcer size. Treatment with intragastric misoprostol preserved the hyperemia and significantly attenuated the exacerbation of mucosal damage or increase in ulcer size produced by tobacco cigarette smoke.

CONCLUSION

These data are consistent with the hypothesis that the attenuation of injury-induced or ulcer margin hyperemia by tobacco cigarette smoke is mediated by the inhibition of endogenous prostaglandins.

Factors influencing reflectance spectrophotometric measurements of gastrointestinal mucosal blood flow

Although the technique of endoscopic reflectance spectrophotometry has been applied in clinical studies, factors that modify the reproducibility of measurements have not been assessed systematically. To determine the limitations of the technique, measurements were made while endoscopic light intensity, systemic oxygen saturation, and orientation of the measuring probe were varied. The effects of hemorrhagic hypotension and exposure of the mucosa to 10% dextrose were also studied. When a large number (n = 480) of measurements in the human colon were considered, endoscopic light significantly decreased the index of oxygen saturation (ISO2) and increased the index of hemoglobin concentration (IHB). The decrease in ISO2, however, was small and unlikely to be of clinical importance despite being statistically significant. In one subject with chronic lung disease and baseline hypoxemia, administration of supplemental oxygen significantly increased oxygen saturation at the finger tip as measured by an oximeter and ISO2 of the buccal mucosa as measured by reflectance spectrophotometry. Varying the angle between the measuring probe and the gastric mucosa in rats from 90 degrees to 60 degrees did not affect ISO2 or IHB measurements. At 45 degrees, however, IHB but not ISO2 was significantly increased. Ischemia subsequent to induction of hemorrhagic hypotension and hyperemia induced by administration of 10% dextrose could be demonstrated reproducibly. We conclude that by lowering the intensity of endoscopic light and providing supplemental oxygen, errors in the measurement of IHB and ISO2, respectively, can be minimized. Minor deviations from the perpendicular orientation do not significantly affect ISO2 and IHB measurements. Attention to these details enhances the accuracy of endoscopic reflectance spectrophotometric recordings of ISO2 and IHB in clinical studies.

Effects of smoking and nicotine on the gastric mucosa: a review of clinical and experimental evidence

Epidemiological and experimental evidence have shown that nicotine has harmful effects on the gastric mucosa. The mechanisms by which cigarette smoking or nicotine adversely affect the gastric mucosa have not been fully elucidated. In this report, clinical and experimental data are reviewed. The effects of nicotine from smoking on gastric aggressive or defensive factors are discussed. Nicotine potentiates gastric aggressive factors and attenuates defensive factors; it also increases acid and pepsin secretions, gastric motility, duodenogastric reflux of bile salts, the risk of Helicobacter pylori infection, levels of free radicals, and platelet-activating factor, endothelin generation, and vasopressin secretion. Additionally, nicotine impairs the therapeutic effect of H2-receptor antagonists and decreases prostaglandin synthesis, gastric mucosal blood flow, mucus secretion, and epidermal growth factor secretion. Although many of the studies provide conflicting results, the bulk of the evidence supports the hypothesis that nicotine is harmful to the gastric mucosa.

Acute effects of smoking during modified sham feeding in duodenal ulcer patients. An analysis of nicotine, acid secretion, gastrin, catecholamines, epidermal growth factor, prostaglandin E2, and bile acids

Smoking is associated with an increased incidence of duodenal ulcer with a high relapse rate, and smokers tend to be slow healers. The etiology responsible for this remains unknown, and there is general disagreement as to whether smoking affects gastric secretion. The aim of the present study was to investigate both aggressive and protective factors in response to vagal stimulation induced by modified sham feeding (MSF) in duodenal ulcer patients when smoking versus not smoking. On smoking days, nicotine concentrations in plasma averaged about 15 ng/ml and were extremely high in saliva and gastric juice (> 1300 and > 800 ng/ml, respectively). MSF induced a significant decrease in intragastric pH during non-smoking (p = 0.01) but not during smoking. Acid output 1 h after MSF was lower on smoking than on non-smoking days (p = 0.02), as was volume secretion (p = 0.02). Plasma gastrin concentrations were significantly increased during MSF on non-smoking days (p = 0.04) but not on smoking days, the concentrations during the whole day being lower on smoking days (p = 0.002). Plasma catecholamine levels were unaffected by MSF, whether smoking or not. However, plasma concentrations of noradrenaline decreased during the smoking of a single cigarette (p = 0.03), whereas those of adrenaline were increased on smoking days (p = 0.02). Epidermal growth factor concentrations were decreased in gastric juice after MSF during non-smoking (p = 0.01) but not during smoking. Although prostaglandin E2 (PGE2) concentrations in gastric juice were unaffected by MSF, PGE2 output increased after MSF whether smoking or not, the increment being non-significantly less during smoking (p = 0.09).(ABSTRACT TRUNCATED AT 250 WORDS)

Does nicotine administration influence intragastric acidity?

Smokers have an increased incidence of duodenal ulcer with a high relapse rate whether they receive maintenance therapy with H2-receptor antagonists or not. They also tend to be slow healers. The etiology behind this is still unknown, and there is general disagreement as to whether smoking affects gastric secretion. In an earlier study we found a small but significant decrease in intragastric pH a short time after smoking a cigarette. The aim of the present investigation was to study whether intragastric pH changed during nicotine administration per se. Nicotine was given as a nasal spray to eight healthy smokers. Nicotine did not induce any acute detectable changes in gastric acidity when the 5-min period before spraying was compared with the 35-min period after spraying (median pH, 1.47 (25-75 percentiles, 1.40-2.32) and 1.55 (25-75 percentiles, 1.42-2.06), respectively). When different time periods during a day with hourly nicotine administration were analyzed, and the results compared with those of a similar day when placebo was given, nicotine was found to impair postprandial gastric neutralization. Median pH during the lunch hour was 1.93 (25-75 percentiles, 1.80-2.37) after nicotine and 2.86 (25-75 percentiles, 2.37-3.70) after placebo; p less than 0.025. Possible explanations for this might be nicotine-mediated effects on gastric motility or gastrin release.