The hydrogen sulfide donor, Lawesson's reagent, prevents alendronate-induced gastric damage in rats

Our objective was to investigate the protective effect of Lawesson's reagent, an H2S donor, against alendronate (ALD)-induced gastric damage in rats. Rats were pretreated with saline or Lawesson's reagent (3, 9, or 27 µmol/kg, po) once daily for 4 days. After 30 min, gastric damage was induced by ALD (30 mg/kg) administration by gavage. On the last day of treatment, the animals were killed 4 h after ALD administration. Gastric lesions were measured using a computer planimetry program, and gastric corpus pieces were assayed for malondialdehyde (MDA), glutathione (GSH), proinflammatory cytokines [tumor necrosis factor (TNF)-α and interleukin (IL)-1β], and myeloperoxidase (MPO). Other groups were pretreated with glibenclamide (5 mg/kg, ip) or with glibenclamide (5 mg/kg, ip)+diazoxide (3 mg/kg, ip). After 1 h, 27 µmol/kg Lawesson's reagent was administered. After 30 min, 30 mg/kg ALD was administered. ALD caused gastric damage (63.35 ± 9.8 mm(2)); increased levels of TNF-α, IL-1β, and MDA (2311 ± 302.3 pg/mL, 901.9 ± 106.2 pg/mL, 121.1 ± 4.3 nmol/g, respectively); increased MPO activity (26.1 ± 3.8 U/mg); and reduced GSH levels (180.3 ± 21.9 µg/g). ALD also increased cystathionine-γ-lyase immunoreactivity in the gastric mucosa. Pretreatment with Lawesson's reagent (27 µmol/kg) attenuated ALD-mediated gastric damage (15.77 ± 5.3 mm(2)); reduced TNF-α, IL-1β, and MDA formation (1502 ± 150.2 pg/mL, 632.3 ± 43.4 pg/mL, 78.4 ± 7.6 nmol/g, respectively); lowered MPO activity (11.7 ± 2.8 U/mg); and increased the level of GSH in the gastric tissue (397.9 ± 40.2 µg/g). Glibenclamide alone reversed the gastric protective effect of Lawesson's reagent. However, glibenclamide plus diazoxide did not alter the effects of Lawesson's reagent. Our results suggest that Lawesson's reagent plays a protective role against ALD-induced gastric damage through mechanisms that depend at least in part on activation of ATP-sensitive potassium (KATP) channels.

Acute toxicity and gastroprotection studies of a new schiff base derived copper (II) complex against ethanol-induced acute gastric lesions in rats

BACKGROUND

Copper is an essential element in various metabolisms. The investigation was carried out to evaluate acute gastroprotective effects of the Copper (II) complex against ethanol-induced superficial hemorrhagic mucosal lesions in rats.

METHODOLOGY/PRINCIPAL FINDINGS

Rats were divided into 7 groups. Groups 1 and 2 were orally administered with Tween 20 (10% v/v). Group 3 was orally administered with 20 mg/kg omeprazole (10% Tween 20). Groups 4-7 received 10, 20, 40, and 80 mg/kg of the complex (10% Tween 20), respectively. Tween 20 (10% v/v) was given orally to group 1 and absolute ethanol was given orally to groups 2-7, respectively. Rats were sacrificed after 1 h. Group 2 exhibited severe superficial hemorrhagic mucosal lesions. Gastric wall mucus was significantly preserved by the pre-treatment complex. The results showed a significant increase in glutathione (GSH), superoxide dismutase (SOD), nitric oxide (NO), and Prostaglandin E2 (PGE(2)) activities and a decrease in malondialdehyde (MDA) level. Histology showed marked reduction of hemorrhagic mucosal lesions in groups 4-7. Immunohistochemical staining showed up-regulation of Hsp70 and down-regulation of Bax proteins. PAS staining of groups 4-7 showed intense stain uptake of gastric mucosa. The acute toxicity revealed the non-toxic nature of the compound.

CONCLUSIONS/SIGNIFICANCE

The gastroprotective effect of the Copper (II) complex may possibly be due to preservation of gastric wall mucus; increase in PGE(2) synthesis; GSH, SOD, and NO up-regulation of Hsp70 protein; decrease in MDA level; and down-regulation of Bax protein.

Involvement of Aquaporin 3 in Helicobacter pylori-related gastric diseases

Background

Gastric cancer is one of the most common and lethal malignant cancers worldwide, and numerous epidemiological studies have demonstrated that Helicobacter pylori (H. pylori) infection plays a key role in the development of gastric carcinomas. Our previous studies showed that aquaporin 3 (AQP3) is overexpressed in gastric carcinoma and promotes the migration and proliferation of human gastric carcinoma cells, suggesting that AQP3 may be a potentially important determinant of gastric carcinoma. However, the role of AQP3 in H. pylori carcinogenesis is unknown.

Methods

The AQP3 protein and H. pylori were detected in human gastric tissues by immunohistochemistry and modified Giemsa staining respectively. AQP3 knockdown was obtained by small interfering (si) RNA. Western blot assays and RT-PCR were used to evaluate the change of AQP3 in the human gastric cancer AGS and SGC7901 cell lines after co-culture with H. pylori. Sprague Dawley rats were orally inoculated with H. pylori to establish a rat model colonized by H. pylori.

Results

The present study found that AQP3 expression correlated with H. pylori infection status in gastric cancer tissues and corresponding normal mucosa, and H. pylori co-culture upregulated AQP3 expression in human gastric adenocarcinoma cells in vitro via the extracellular signal-regulated kinase signaling pathway. H. pylori infection also increased AQP3 expression in gastric mucosa colonized by H. pylori in a Sprague Dawley rat model.

Conclusions

These findings provide further information to understand the mechanism of H. pylori carcinogenesis and a potential strategy for the treatment of H. pylori-associated gastric carcinoma.

Acrylonitrile-induced gastric toxicity in rats: the role of xanthine oxidase

BACKGROUND

Acrylonitrile (ACN) is an extensively produced aliphatic nitrile. The gastrointestinal tract is an important target organ for ACN toxicity. The objective of the present study was to investigate the role of xanthine oxidase (XO) in ACN-induced gastric toxicity in rats.

MATERIAL/METHODS

We assessed the effect of ACN on oxidative stress parameters as xanthine oxidase (XO) and total xanthine dehydrogenase (XD)/ XO activity, superoxide anion (O(2)(.-)) production, reduced glutathione (GSH) levels and lipid peroxidation in gastric tissues.

RESULTS

A single oral dose of ACN (25 mg/kg) caused a significant enhancement in XO activity. ACN also caused a significant depletion of GSH levels, enhanced O(2)(.-) production and increased lipid peroxidation in the time-course experiment. In the dose-response experiment, ACN accelerated the conversion of XD to XO, with a significant depletion of gastric GSH in a dose-related manner. A strong negative correlation existed between the levels of GSH and the percentage enhancement in XO activity (r =-0.997). (O(2)(.-)) production and malondialdehyde (MDA) formation were significantly elevated in a dose-related manner. Pretreatment with allopurinol (50 mg/kg) significantly protected against ACN-induced rise in XO activity, depletion of GSH, and elevated production of (O(2)(.-)). However, pretreatment with diethyl maleate (DEM; 100 mg/kg) significantly aggravated the ACN-induced GSH depletion and rise in XO activity. Furthermore, DEM significantly enhanced (O(2)(.-)) and MDA production.

CONCLUSIONS

The present study indicates that enhancement of XO activity could be implicated in ACN-induced gastric damage in rats.

Lysozyme overexpression in fundic gland polyps

Backgroud: Helicobacter pylori (Hp) rarely proliferates in patients with fundic gland polyps (FGPs). We recently found that FGPs express lysozyme, one of the natural defence substances against infection. We aimed to assess the degree of lysozyme expression in a cohort of consecutive FGPs.

MATERIALS AND METHODS

A total of 153 gastric biopsies were investigated: 93 with FGPs, 30 with normal mucosa (Nm), 15 with Hp-induced chronic gastritis (Hp-gastritis) and 15 with chronic gastritis without Hp infection (non-Hp-gastritis). Sections were stained with anti-lysozyme (muramidase).

RESULTS

Lysozyme was slightly to moderately expressed in the surface and foveolar pits, being markedly expressed in the neck glands in Nm, in non-Hp and Hp-gastritis. The ratio of lysozyme neck glands-foveoli was higher in non-Hp than in Nm and even higher in Hp-gastritis. In FGPs, lysozyme was markedly expressed in the surface, the foveolar pits and the cells that partly or entirely covered the microcysts.

DISCUSSION AND CONCLUSION

While the moderate expansion of the lysozyme-producing cells of the neck glands in Hp-gastritis might be insufficient to eradicate these bacteria, the overproduction of lysozyme in the epithelium covering FGP could be an explanation for the lack of Hp proliferation in these patients.

Role of endothelial nitric oxide synthase in aggravation of indomethacin-induced gastric damage in adjuvant arthritic rats

The role of nitric oxide synthase (NOS) isozymes in the aggravation of indomethacin-induced gastric damage in adjuvant arthritic rats was investigated. Two weeks after injection of Freund's complete adjuvant, the animals were given indomethacin, and the stomach was examined for damage 4 h later. Indomethacin caused hemorrhagic lesions in the normal rat stomach, and these lesions were markedly aggravated in arthritic rats. Pretreatment with L-NAME (a nonselective inhibitor of NOS) and aminoguanidine (a relative selective inhibitor of iNOS) did not affect the ulcerogenic response in normal rats but dose-dependently prevented the aggravation of lesions in arthritic rats, but the effect of aminoguanidine was apparently less than that of L-NAME. The increased ulcerogenic response in arthritic rats was significantly suppressed by 1400 W (a selective inhibitor of iNOS) and L-NIO (a selective inhibitor of eNOS) but not by L-NPA (a selective inhibitor of nNOS). The concurrent administration of 1400 W and L-NIO almost totally abolished the aggravation of damage in arthritic rats. The expressions of eNOS and iNOS but not nNOS in the gastric mucosa were clearly enhanced in arthritic rats. Mucosal levels of non-protein sulfhydryls were significantly lower in arthritic rats than those in normal rats. The aggravation of damage in arthritic rats was significantly prevented by glutathione. These results suggest that the increased ulcerogenic response to indomethacin in arthritic rat stomachs is mediated by NO derived from eNOS in addition to iNOS. It is assumed that eNOS/NO may act harmfully on the gastric mucosa of arthritic rats with mucosal SH deficiency.

[Clinical and morphological characteristics and some mechanisms of portal gastroduodenopathy in liver cirrhosis]

We have found out the clinical presentations and peculiarities of endoscopic and morphologic view of pathologies of mucous membrane of gastroduodenal zone caused by liver cirrhosis. We have examined 74 patients with liver cirrhosis of viral and nonviral etiology using the clinical, endoscopic, morphologic and immunohistochemical methods.We have found that during liver cirrhosis morphometric rates of epithelial cells of mucous coat of stomach that produce somatostatin and endothelin-1 decrease and morphometric rates of epithelial cells that produce nitrogen oxide synthase increase. We have also found out that during liver cirrhosis proliferate activity decrease and apoptosis of epithelial cell of mucous coat of stomach increase.

Association of myeloperoxidase -463 G/A polymorphism with clinical outcome of Helicobacter pylori infection in Iranian patients with gastrointestinal diseases

BACKGROUND

Polymorphisms in the immune related genes are important in the clinical outcome of Helicobacter pylori infection. Myeloperoxidase -463 G/A polymorphism has been shown to reduce enzyme expression and activity.

OBJECTIVE

the aim of the present study is to investigate the association of myeloperoxidase G-463A polymorphism with clinical outcome of Helicobacter pylori infection.

METHODS

two hundred and eighty five patients with positive culture of Helicobacter pylori from their gastric biopsies are included in this study. Human leukocyte DNA was extracted using salting out method and myeloperoxidase G-463A polymorphism was investigated by PCR-RFLP. All clinicopathological data were collected from individual records.

RESULTS

When the patients were categorized according to the high (GG) and low + intermediate (AG+AA) genotypes of myeloperoxidase producers, there was a significant association between myeloperoxidase G-463A genotypes and clinical outcome of Helicobacter pylori infection (p=0.006). In search for combined effect of cagA status and myeloperoxidase genotypes on clinical presentations, only in cagA- Helicobacter pylori infected patients a significant association between myeloperoxidase genotypes and clinical outcome was found (p=0.0001). Also this association was found only in patients infected with vacA s1m1 genotype (p=0.008).

CONCLUSIONS

Our findings suggest that the myeloperoxidase G-463A polymorphism is a host genetic factor which determines the clinical outcome of Helicobacter pylori infection. Moreover, the combination of host and bacterial genetics could provide a better understanding of clinical outcome after infection with Helicobacter pylori.

Gastric graft-versus-host disease revisited: does proton pump inhibitor therapy affect endoscopic gastric biopsy interpretation?

Accurate diagnosis of gastrointestinal graft-versus-host disease (GvHD) is important, as it contributes significantly to postallogeneic stem cell transplant (SCT) morbidity and mortality. To test the hypothesis that proton pump inhibitor (PPI) therapy may interfere with histologic evaluation of gastric GvHD by inducing apoptosis, we evaluated epithelial apoptotic body counts in antral and fundic biopsies from SCT recipients and control patients, both taking and not taking PPIs at the time of endoscopic biopsy. Hematoxylin and eosin-stained slides of gastric biopsies from 130 patients (75 allogeneic SCT with GvHD on clinical and histologic grounds, and a comparison group of 55 age- and sex-matched nontransplant patients with histologically normal gastric biopsies) were reviewed. The groups were further stratified into patients taking (PPI+) and not taking PPIs (PPI-) at the time of biopsy. Apoptotic bodies (AB)/10 (400 x) high power fields (HPF) were quantified for each case. Mean apoptotic body counts were then calculated for each case group. Seventy antral cases (31 control and 39 transplant) were also evaluated via gastrin immunohistochemistry, and the mean number of gastrin positive cells/400 x HPF calculated. In the PPI- groups, apoptosis was increased in biopsies from transplant patients, compared with controls, both in antral and fundic mucosa. In PPI+ patients, there was significantly more apoptosis in the gastric body in transplant patients than in controls. However, comparing antral biopsies from control and transplant PPI+ patients, there was no significant difference in AB quantitation. More apoptosis was seen in antral biopsies from PPI+ control patients when compared with PPI- control patients (P = 0.009). Mean numbers of gastrin positive cells/400 x HPF were increased in both control and transplant patients taking PPIs (85 and 58, respectively) compared with samples from those patients not taking PPIs (48 and 51, respectively). PPI therapy is associated with increased apoptosis in antral biopsies and may interfere with the evaluation of GvHD in biopsies from this site. A similar increase in apoptosis was not seen in fundic biopsies; biopsy of the gastric fundus rather than antrum may be preferable for the diagnosis of upper gastrointestinal GvHD.

Histochemical and histopathological study of the gastric mucosa in the portal hypertensive gastropathy

It has been studied "in situ" the action of NADH2-cytochrome C reductase, an aerobe oxidative enzyme, in comparison to lactate dehydrogenase, a glycolitic enzyme in the gastric mucosa and with portal hypertensive gastropathy (PHG) accompanied by morpho-pathological observations. In the normal gastric mucosa, the aerobe oxidative metabolism is predominant over the anaerobe one in all types of cells, but in different intensities (medium in the surface epithelium and low in the vascular endothelium, weak, medium, intense and very intense in fibroblasts and in secretory cells of fundic glands and macrophages). In the portal hypertensive gastropathy, this type of metabolism decreases and the anaerobe metabolism increases, tending to equal the first, especially in the glandular cells. The oxidative activity decreases in the surface epithelium and in the vascular endothelium, increases in cells of the inflammatory infiltrate and in fibroblasts and mast cells.

Effect of different organic acids (citric, malic and ascorbic) on intragastric urease activity

BACKGROUND

The mechanism of citric acid-enhanced Helicobacter pylori urease activity remains unclear.

AIM

To compare ascorbic, citric and malic acid given at the same concentration and pH on intragastric urease activity.

METHODS

Volunteers received 40 mg of famotidine the evening prior to breath testing. After an overnight fast volunteers were randomized to receive 100 mL of water or 100 mm citric, malic, or ascorbic acid, pH 2.3 containing 75 mg of 13C-urea. At 15 min a second 100 mL solution of one of the test solutions was taken without added urea.

RESULTS

Twelve volunteers were studied (eight men, four women, age 19-57, median 50.7) in a randomized-crossover study. The mean breath test result at 30 min with ascorbic (17.5 +/- 5), malic (25.8 +/- 5) and citric acid (29.5 +/- 5) were all significantly greater than with water (9.5 +/- 3). Citric and malic acid were similar (P = 0.699) and significantly greater than ascorbic acid (P < 0.02). When the ascorbic acid was followed by citric acid, the result was similar to that with citrate alone (25.8 +/- 4) and greater than with ascorbic then ascorbic (P = 0.026).

CONCLUSIONS

Enhancement of H. pylori urease activity is not strictly a function of the pH. We propose the effect is related to differential effects of the availability of nickel, which is required for urease activity. Citric acid and malic acid were essentially equivalent such that malic acid could substitute for citric acid in the UBT; ascorbic acid would be a poor choice.

Gastroprotection by pentoxyfilline against stress-induced gastric damage. Role of lipid peroxidation, antioxidizing enzymes and proinflammatory cytokines

Impairment of blood perfusion in gastric mucosa results in the formation of erosions and ulcers. Nitric oxide (NO), produced via activity of NO-synthase (NOS), appears to be a one of major factors, involved in the regulation of the gastric blood flow (GBF). Inhibition of this enzyme by N-nitro-L-arginine (L-NNA) results in local decrease of NO production, reduces GBF and impairs gastric mucosal integrity, the effects that can be reversed by the pretreatment with L-arginine, the NOS substrate. However, little information is available regarding the contribution of reactive oxygen species (ROS)-induced lipid peroxidation and NO to the mechanism of gastric mucosal integrity. Therefore, the aim of our present study was to determine the action of pentoxyfilline (PTX), an inhibitor of tumor necrosis factor alpha (TNFalpha) with or without NOS inhibition by L-NNA administration in rats with water immersion and restraint stress (WRS)-induced gastric lesions. Experiments were carried out on 100 male Wistar rats. The gastric blood flow (GBF) was measured using laser Doppler flowmeter. The area of gastric lesions was determined by planimetry and the levels of proinflammatory cytokines (IL-1beta and TNFalpha) were measured by ELISA. Colorimetric assays were employed to determine gastric mucosal levels of lipid peroxidation products, such as malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) and antioxidant enzymes including superoxide dismutase (SOD) activity, as well as tissue concentration of reduced glutathione (GSH). Administration of PTX significantly attenuated the gastric lesions, induced by 3.5 h of WRS and this was accompanied by the rise in the GBF and a significant decrease in plasma proinflammatory cytokines (IL-1beta and TNFalpha) levels, as well as the reduction of lipid peroxidation. Exposure of rats to WRS suppressed the SOD and GSH activities and these effects were reversed by PTX. The protective and hyperemic effects of PTX, as well as an increase in mucosal SOD activity and GSH concentration were counteracted by pretreatment with L-NNA, but restored by the pretreatment with L-arginine, a NOS substrate. We conclude that PTX exerts beneficial, gastroprotective effect against WRS-induced gastric lesions due to enhancement in gastric microcirculation, possibly mediated by the enhanced NOS activity as well as local action of NO and by the attenuation of oxidative metabolism and generation proinflammatory cytokines.

PAR-2: structure, function and relevance to human diseases of the gastric mucosa

PAR-2 (protease-activated receptor 2), a G-protein-coupled receptor activated by certain serine proteases such as trypsin and tryptase, is now considered a physiologically important molecule and also a novel target for drug development. PAR-2 is widely distributed in the mammalian body, especially throughout the alimentary system. PAR-2 plays various roles in the alimentary, circulatory, respiratory and neuronal systems. In the gastric mucosa, PAR-2 modulates multiple functions and exerts mucosal cytoprotection mainly by activating sensory neurons. Thus, PAR-2 would appear to be a therapeutic target for treatment of gastric mucosal injury. Agonists and/or antagonists for PAR-2 might also be applicable to the clinical treatment of patients with inflammatory diseases in other organs.

Prevalence and clinical characterization of gastric Helicobacter species infection of dogs and cats in Korea

This study was carried out to evaluate the prevalence and clinical characterizations of gastric Helicobacter spp. infection of dogs and cats in Korea. The prevalence of Helicobacter spp. infection of dogs and cats determined by urease test was 78.4% and 64%, respectively, although Helicobacter genus-specific PCR assay showed that it was 82.3% and 84%. Urease mapping results based on urease test showed that total positive rate of tested tissues from clinically abnormal dogs was significantly higher than that from clinically normal dogs (p=0.0018; Odds ratio = 6.118; 95% Confidence Interval = 1.96-19.103). These findings were consistent with the results of Helicobacter genus-specific PCR assay which showed that positive rate of the fundus (100%) and the antrum (100%) of clinically abnormal dogs was significantly higher than that of same gastric regions of clinically normal dogs (77.5 and 67.5% respectively). In comparison of gastric regions between clinically normal dogs and abnormal dogs, positive rate of urease test for the fundus (100%) and body (90.9%) in clinically abnormal dogs was significantly higher than that of abnormal dogs (72.5% and 57.5% respectively; p<0.05). The results of urease mapping in dogs and cats also indicated that Helicobacter colonization in the fundus was more dense compared with the density in the body and antrum. In Helicobacter species-specific PCR assay for dogs, 32 of 42 fundic tissues (76.2%) were positive for H. heilmannii and two (4.8%) were positive for H. felis. In cats, 18 of 21 fundic tissues (85.7%) were positive for H. heilmannii and 2 (9.5%) were positive for H. felis. Gastritis scores of fundic tissues from clinically abnormal infected dogs were similar to that from noninfected dogs and evidence of upregulation of IL-1beta, IL-8, and TNF-alpha mRNA was not detected in gastric fundic tissues from clinically abnormal infected dogs. This study suggested that Helicobacter spp. infection in domestic dogs including private owned pet dogs and cats is highly prevalent usually with no clinical sign but high density of colonization can be related to gastrointestinal signs

Molecular resistance testing of Helicobacter pylori in gastric biopsies

OBJECTIVE

To evaluate simultaneous diagnosis of infection and molecular resistance testing of Helicobacter pylori.

METHODS

Gastric biopsies were obtained from 26 rapid urease-positive and 51 rapid urease-negative test kits used to diagnose H pylori infection. Following glass bead-assisted DNA isolation, amplification of H pylori 16S ribosomal DNA (rDNA), glmM, and 23S rDNA target genes was performed.

RESULTS

Helicobacter pylori DNA was successfully amplified from 100% (26/26) of urease-positive and 3.9% (2/51) of urease-negative gastric biopsies. Subsequent restriction enzyme-mediated digestion of 23S rDNA amplification products revealed that 17% (4/24) of urease-positive and H pylori DNA-positive biopsy specimens contained point mutations (A2142G or A2143G) associated with clarithromycin resistance. Helicobacter pylori DNA from gastric biopsies was successfully amplified 8 weeks following rapid urease testing.

CONCLUSION

Helicobacter pylori genotyping may be used to detect macrolide-resistant H pylori in individuals prior to initiation of therapy or in patients refractory to anti-H pylori therapy. Two urease-negative specimens yielded Helicobacter DNA distinct from that of H pylori and indicated the need for further investigations of Helicobacter species present in the human stomach.

Insulin restores neuronal nitric oxide synthase expression and function that is lost in diabetic gastropathy

Gastrointestinal dysfunction is common in diabetic patients. In genetic (nonobese diabetic) and toxin-elicited (streptozotocin) models of diabetes in mice, we demonstrate defects in gastric emptying and nonadrenergic, noncholinergic relaxation of pyloric muscle, which resemble defects in mice harboring a deletion of the neuronal nitric oxide synthase gene (nNOS). The diabetic mice manifest pronounced reduction in pyloric nNOS protein and mRNA. The decline of nNOS in diabetic mice does not result from loss of myenteric neurons. nNOS expression and pyloric function are restored to normal levels by insulin treatment. Thus diabetic gastropathy in mice reflects an insulin-sensitive reversible loss of nNOS. In diabetic animals, delayed gastric emptying can be reversed with a phosphodiesterase inhibitor, sildenafil. These findings have implications for novel therapeutic approaches and may clarify the etiology of diabetic gastropathy.

Gastropathy and defense mechanisms in common bile duct ligated portal hypertensive rats

Portal hypertensive gastropathy is associated with a broad spectrum of gastric mucosal damage inspite of decreased gastric acid secretion, suggestive of compromised endogenous protective mechanisms. To determine the mechanisms of damage in portal hypertensive gastropathy we measured lipid peroxidation, glutathione, antioxidant and lysosomal enzymes in gastric mucosal homogenates from male Wistar rats with elevated intrasplenic pulp pressure, eighteen days after common bile duct ligation. Thiobarbituric acid-reactive substances and lysosomal enzymes (beta-glucuronidase and acid phosphatase) were increased in the common bile duct ligated group as compared to the sham-operated group. The levels of antioxidant defense enzymes, superoxide dismutase, glutathione peroxidase, catalase and glutathione were decreased as compared to the sham-operated controls. Pre-operative vitamin E administration decreased mucosal lipid peroxidation increased the levels of antioxidant defense enzymes and lowered the lysosomal enzymes. The plasma vitamin E levels in this group were lower when compared to animals receiving it post-operatively. In conclusion, free radical and lysosomal enzyme mediated damage may play a role in portal hypertensive gastropathy.

Phenotype 2 of deoxyribonuclease I may be used as a risk factor for gastric carcinoma

BACKGROUND

Human deoxyribonuclease I (DNase I) (EC3.1.21.1) is one of the candidate nucleases that acts in mammalian cells during apoptosis. Genetic polymorphism of DNase I has been classified into 15 phenotypes controlled by 5 autosomal codominant alleles. The purpose of this study was to determine whether DNase I polymorphism is closely related to the incidence of gastric carcinoma.

METHODS

The phenotype distribution was examined using urine samples obtained from unrelated Japanese patients with gastric carcinoma (n = 97) and benign gastric diseases (n = 76). Phenotyping was performed using isoelectric focusing electrophoresis in thin polyacrylamide gel and immunoblotting with an antihuman DNase I antibody.

RESULTS

A close statistical association was found between patients with gastric carcinoma and a high frequency of DNase I phenotype 2. However, there was no significant difference in the phenotype distribution between the group of patients with benign gastric diseases and the controls.

CONCLUSIONS

The findings of the current study suggest that DNase I phenotype 2 may be a marker for gastric carcinoma. Therefore, compared with other phenotypes, DNase I phenotype 2 may have potential for identifying patients who are at risk of harboring or developing gastric carcinoma.

[Character of changes in indicators of proteinase and proteinase inhibitor activity in gastroenterological pathology in children]

The aim of this study was to determine trypsin-lake proteinase activity, chymotrypsin-like proteinase activity, trypsin, alpha 1-antitrypsin and alpha 2-macroglobulin levels in blood serum at the children with gastroenterological pathology. These parameters did not chang at the children with functional disorder of stomach and duodenum. The stable balance between proteinases and inhibitors was determined only at the duration of the disease not more 5 years. The absence of normal levels these enzymes after traditional treatment was explain the necessity to continue the therapy at home with control of enzymes' levels.

Metabolism of ethanol and some associated adverse effects on the liver and the stomach

Current knowledge of alcohol oxidation and its effects on hepatic metabolism and its toxicity are summarized. This includes an evaluation of the relationship of the level of consumption to its interaction with nutrients (especially retinoids, carotenoids, and folate) and the development of various stages of liver disease. Ethanol metabolism in the stomach and its link to pathology and Helicobacter pylori is reviewed. Promising therapeutic approaches evolving from newly gained insight in the pathogenesis of medical complications of alcoholism are outlined. At present, the established approach for the prevention and treatment of alcoholism are outlined. At present, the established approach for the prevention and treatment of alcoholic liver injury is to control alcohol abuse, with the judicial application of selective antioxidant therapy, instituted at early stages, prior to the social or medical disintegration of the patient, and associated with antiinflammatory agents at the acute phase of alcoholic hepatitis. In addition, effective antifibrotic therapy may soon become available.

Role of granulocyte elastase in indomethacin-induced gastric mucosal lesion formation in rats

To investigate whether granulocyte elastase may be involved in indomethacin-induced gastric mucosal injury, we examined the effects of the granulocyte elastase inhibitors ONO-5046 and L-658,758 on gastric mucosal lesion formation in rats given indomethacin. Both gastric mucosal lesion formation and gastric mucosal vascular damage were markedly attenuated in animals with leukocytopenia and in those given granulocyte elastase inhibitors. The administration of indomethacin significantly increased gastric myeloperoxidase activity, a measure of leukocyte accumulation, 3 hours after the administration of indomethacin compared with activity in animals receiving saline solution. The administration of ONO-5046 or L-658,758 significantly prevented this increase. Histologic examinations revealed submucosal edema and marked infiltration by leukocytes, as well as widespread necrosis with loss of surface epithelium. ONO-5046 and L-658,758 markedly prevented these histologic changes. Although cimetidine significantly prevented mucosal lesion formation, it did not inhibit either granulocyte elastase release from activated neutrophils in vitro or gastric accumulation of leukocytes in vivo. These results suggest that granulocyte elastase as well as gastric acid may play an important role in the pathologic process by which indomethacin induces gastric mucosal lesions.

Cytochrome P4502E1 (CYP2E1) genetic polymorphism in a case-control study of gastric cancer and liver disease

Cytochrome P4502E1 (CYP2E1) activates carcinogenic N-nitrosamines, benzene, urethane and other low molecular weight compounds. This enzyme is also inducible by ethanol, and metabolizes alcohol. A restriction fragment length polymorphism (RFLP) using the Rsa I restriction enzyme has been identified in the CYP2E1 transcription regulatory region; recent studies suggest that this polymorphism may affect gene expression. We investigated the frequency of the Rsa I RFLP in a Japanese population in relation to gastric cancer and liver disease susceptibility. The frequency of this polymorphism was determined in 150 gastric cancer, 16 hepatocellular cancer, 48 liver cirrhosis and 203 benign gastric disease (controls) patients. This preliminary study shows no association of the specific genotype with gastric cancer in all subjects (odds ratio = 1.04, 95% CI = 0.74-3.08 for the heterozygote and 0.57, 95% CI = 0.22-1.50 for the homozygous rare allele, respectively). To further confirm this lack of association, an age and gender matched case-control study should be performed. Separately, there was no association of the Rsa I RFLP with hepatocellular carcinoma (p = 0.911), but there was a suggested difference between the non-viral associated liver cirrhosis patients and control patients. Thus, this polymorphism may be related to ethanol metabolism and consequential liver diseases in a Japanese population.

The pharmacology of the gastric acid pump: the H+,K+ ATPase

The gastric H+,K+ ATPase--the gastric acid pump--is the molecular target for the class of antisecretory drugs called the proton-pump inhibitors (PPIs). These compounds--omeprazole, lansoprazole, and pantoprazole--contain, as their core structure, 2-pyridyl methylsulfinyl benzimidazole. The H+,K+ ATPase is a heterodimer composed of a 1034-amino acid catalytic alpha peptide and a glycosylated 291-amino acid beta subunit. The alpha subunit probably contains 10 membrane-spanning sequences; the beta, a single transmembrane segment. The PPIs have a pKa of about 4.0; hence they accumulate only in the acidic secretory canaliculus of the stimulated parietal cell. Here they undergo conversion to a cationic sulfenamide, which then reacts with available cysteines on the extracytoplasmic face of the alpha subunit. Omeprazole reacts and forms disulfide bonds with cys813(822) and cys892; lansoprazole, with cys813(822), cys892, and cys321; and pantoprazole, with cys813 and -822. The antisecretory effect of the drugs reflects their short plasma half-life (approximately 60 min), the number of active pumps during that time, and the recovery of pumps following biosynthesis and reversal of inhibition. These drugs also show synergism with either amoxicillin or clari- thromycin in eradicating Helicobacter pylori, an organism shown to be important in duodenal and gastric ulcer disease. Their action is probably due to elevation of pH in the environment of the organism, rather than to any direct action.

[Antioxidant enzyme activity in the gastric mucosa in precancerous conditions]

BACKGROUND

The primary defense against oxidation damage of tissues are anti-oxidant enzymes, e.g. superoxide dismutase, catalase and glutathione peroxidase. Some non-enzymatic substances have a significant anti-oxidant action (e.g. vitamin C, E, beta-carotene and others). The objective of the present work was to follow up the Cu/Zn superoxide dismutase activity, catalase and glutathione peroxidase (anti-oxidant enzymes of the gastric mucosa) in subjects with the risk of developing gastric cancer, e.g. those suffering from atrophic gastritis, hyperplastic polyps and gastric adenoma.

METHODS AND RESULTS

The authors examined 80 subjects (50 men and 30 women) aged 25 - 71 years. In all during endoscopic examination bioptic specimens of the mucosa were taken at standard sites of the gastric corpus and antrum for histological and enzymological examination. Enzymological examination: activity of Cu/Zn-superoxide dismutase (Randox Lab. Ltd. GB kit), catalase activity (modified method of Cavarocchia et al.) and glutathione peroxidase activity (method according to Paglia and Valentine). The Cu/Zn-superoxide dismutase activity was elevated in the group of patients with gastritis after gastrectomy (67%) and with gastric adenoma (35%), the catalase activity in patients with gastritis after gastrectomy (40%) and the glutathione peroxidase activity in patients with the diagnosis of gastritis after gastrectomy (185%), atrophic gastritis (46%) hyperplastic polyp (50%) and gastric adenoma (50%).

CONCLUSIONS

The increased activity of anti-oxidant enzymes was due to a higher concentration of the superoxide anion radical, hydrogen peroxide and organic peroxides (lipoperoxides); the source of active types of oxygen are phagocytic leucocytes in the chronically inflamed gastric mucosa.

O6-alkyltransferase activity in normal and abnormal gastric mucosa

The activity of the DNA repair enzyme O6-alkyltransferase has been studied in a series of stomachs with abnormal gastric mucosa and the activities found compared with those in normal stomachs. Enzyme activities found in stomachs with the macroscopic abnormalities of gastric ulcer, duodenal ulcer or gastric cancer were not significantly different from normal. In those stomachs where there was histological evidence of chronic atrophic gastritis or intestinal metaplasia however enzyme activities (mean 398 fmole/mg) were significantly higher than normal (mean activity 228 fmole/mg activity P < 0.001). We speculate that the conditions which stimulate these histological changes also give rise to induction of O6-alkyltransferase.

The clinical and laboratory studies of superoxide dismutase activity in the human whole blood with early gastric cancer

In this study, we tried to evaluate the usefulness of Superoxide Dismutase (SOD) activity in detecting gastric cancer. SOD was determined according to M. Minami and H. Yoshikawa, a simple and inexpensive assay method. For 11 fibrogastroscopy and pathological proved gastric cancer cases, the average levels of SOD activity was found significantly lower than 30 patients with gastric diseases, 8 patients with atypical hyperplasia and 32 controls.

Helicobacter pylori gastric infection in gnotobiotic beagle dogs

Establishment of infection with Helicobacter pylori and gastritis in nonhuman species is currently only successful in gnotobiotic piglets. This study was designed to determine whether H. pylori will colonize the gastrointestinal tract of gnotobiotic dogs. Gnotobiotic beagle pups were derived by standard methods. Group A (five dogs) was orally challenged with 3 x 10(8) H. pylori at 7 days of age. Group B (two dogs) received only peptone water but was contact-exposed beginning on day 23 postinfection (p.i.). Necropsy was performed on dogs on day 30 p.i. H. pylori colonized the stomach of all dogs (groups A and B). Urease map analysis correlated with the microbiologic findings and indicated that the density of colonization was less than that observed in human tissue. Organisms were also recovered from the pharynx, esophagus, duodenum, and rectum of 1, 2, 2, and 1 dog, respectively. All group A and one group B dog developed serum immunoglobulin G specific for H. pylori by day 30 p.i. Gross lesions were restricted to the stomach and consisted of small (less than 1 mm) lymphoid follicles. Microscopically, there were focal to diffuse lymphoplasmacytic infiltrates with follicle formation and mild to moderate infiltration of neutrophils and eosinophils in the gastric lamina propria. With the Warthin-Starry silver stain, organisms were seen on the surface of the gastric epithelial cells, beneath the mucus layer. We conclude that H. pylori colonizes the stomachs of gnotobiotic dogs for at least 1 month and the lesions resemble those seen in humans. H. pylori is transmissible by contact from infected to noninfected dogs.

[Protein kinase activity and cAMP level in gastric mucosa in non-neoplastic diseases]

Activity of cAMP-dependent and -independent protein kinases as well as content of cAMP were studied in biopsy preparations of gastric mucosal membranes obtained from patients with superficial gastritis, erosion, ulcer, adenomatous polyps and ulcer after treatment with laser irradiation. All the patterns studied were similar in preparations of adenomatous polyps and normal mucosal membrane. Activity of cAMP-independent protein kinases was increased under conditions of erosion, ulcer, gastroduodenal reflux and, especially, in ulcer tissue treated with laser. However, the ratio between cAMP-independent and -dependent phosphorylation was increased only in 50% of ulcerous diseases and in gastroduodenal reflux. The equilibrium of cAMP-dependent and -independent phosphorylation was not altered in the other impairments studied even though benign proliferation was stimulated using laser irradiation.

Discrepancies between gastric mucosal and urinary pepsinogen A patterns and in vitro synthesis and secretion of human pepsinogen

The relationship between electrophoretic pepsinogen A (PGA) patterns from urine and gastric mucosa was studied in healthy volunteers and in patients with various gastric disorders. Discrepancies between urinary and gastric PGA patterns were found in 63.3% of the individuals. In 9% of the subjects with these discrepancies, the phenotype class in urine was different from that in gastric mucosa. The differences were found in all diagnostic groups. The highest frequency of differences was found in patients with gastric ulcer. The differences were not related to the serum PGA level. More than 80% of the differences were caused by a lower relative intensity of pepsinogen A fraction 5 (Pg5) in urine than in gastric mucosa. The possible origin of differences in PGA isozymogen patterns was studied by organ culture of gastric biopsies. In vitro synthesis and secretion of pepsinogens were studied by electrophoresis and autoradiography. The synthesis rate of PGA in biopsies of 1-2 mm diameter was 40-100 ng/hr. Posttranslational modification of PGA isozymogens was demonstrated. Pg2 and part of Pg4 probably are secondary products of Pg3 and Pg5, respectively. In some individuals the secretion rate of Pg3 was low compared to the other isozymogens. The conversion of Pg3 into Pg2 and the differential secretion of the isozymogens may explain some of the discrepancies between gastric and urinary PGA patterns.

Sulfation of glycolipids by human gastric mucosa in disease

The activity levels of sulfotransferase enzymes involved in the transfer of sulfate from 3'-phosphoadenosine 5'-phosphosulfate to mucosal membrane and mucus gel glycolipids were studied in fundic and antral mucosal biopsies of patients with severe and chronic gastritis, gastric atrophy, gastric ulcer, and gastric cancer. With sulfotransferase which catalyzes the sulfation of mucus triglucosyl glyceroglucolipid increase in enzyme activity over the control was observed in patients with chronic and severe gastritis, and gastric atrophy, while a decrease in activity was noted in patients with gastric ulcer and gastric cancer. The differences were significant at p less than 0.001 for severe gastritis, gastric ulcer and gastric cancer. The increase in activity of sulfotransferase enzyme involved in the sulfation of membrane galactosylceramide over the control was observed in antral and fundic mucosa of all patients. Significant (p less than 0.001) differences were found in patients with severe gastritis, gastric atrophy and gastric ulcer. The results indicate that considerable changes in the activities of the mucosal sulfotransferase enzymes involved in the synthesis of membrane and secretory sulfolipids occur in gastric disease.

Glutathione and GSH-dependent enzymes in the human gastric mucosa

The gamma-glutamyl-transferase activity, the total glutathione content, the GSH-peroxidase activity, and the GSH S-transferase activity using an aryl substrate were estimated in the S9 fraction of gastric biopsy specimens taken from patients with normal stomach morphology (n = 24), acute gastritis (n = 15), chronic-atrophic gastritis (n = 10), gastric ulcer (n = 9), and carcinoma of the stomach (n = 12). The total glutathione content of normal gastric mucosal specimens was significantly higher than that of human liver biopsy specimens, whereas the GSH-peroxidase and the GSH S-aryltransferase activities were much lower than those found in the liver. Specimens of gastric ulcer had significantly lower enzyme activities of GSH-peroxidase and GSH-aryltransferase, whereas gastric cancer tissue had significantly lower concentrations of total glutathione. The intraindividual comparison of tumorous and non-tumorous tissue showed a consistent decrease of total glutathione as well as of GSH-aryltransferase activity in carcinomatous tissue.

Increased mucosal lysosomal enzyme activity in sepsis-associated gastric lesions

The role of lysosomal enzymes in the pathology of gastric mucosal damage has been demonstrated for stress-, aspirin-, and bile-induced acute gastric erosions. In a septic canine model we measured gastric mucosal beta-N acetylhexosaminidase activity during the evolution of septic-induced acute gastric erosions. In the first septic day bleeding acute gastric erosions developed in the fundus while in the antrum minimal petechiae appeared. During this period beta-N acetylhexosaminidase activity significantly increased in fundic mucosa that was grossly normal but significantly decreased in grossly normal antral mucosa. These experiments thus demonstrate that during the evolution of septic gastric mucosal damage the earliest abnormality is significant increase in mucosal lysosomal enzyme activity.

Immunoperoxidase study of the secretory immunoglobulin system and lysozyme in normal and diseased gastric mucosa

Using an immunoperoxidase technique the distribution of secretory component, IgA, and lysozyme has been investigated in normal, inflamed, dysplastic, and carcinomatous gastric mucosa. Apart from pyloric glands which contain lysozyme, normal gastric mucosa stains negatively for all three antigens. In gastric mucosa neck cells appear to adapt by synthesising secretory component and lysozyme and transporting IgA. Intense staining for the three antigens is seen in dysplastic gastric epithelium and in well-differentiated intestinal type carcinomas. With progressive de-differentiation the tumours lose the ability to synthesise secretory component and lysozyme. Carcinomas of the diffuse type stain positively for secretory component and lysozyme and individual cells appear to take up IgA even in the absence of surrounding IgA containing plasma cells. These functional properties are retained in lymph node metastases. It is suggested that secretory component synthesising malignant cells might take up circulating dimeric IgA and that this could be a reflection of an important physiological mechanism.

LDH isoenzyme pattern of uninvolved gastric mucosa of patients with gastric carcinoma and benign gastric disease

The LDH isoenzyme pattern of the uninvolved mucosa of gastric cancer patients differs as regards the LDH isoenzyme pattern from that of similar tissue of patients with benign gastric disease; the former tissue is characterised by a high M/H ratio of the LDH isoenzymes (M and H sub-units). A high M/H ratio characterises antral mucosa when the latter is compared with fundic mucosa. Mucosa showing superficial and atrophic gastritis also has a higher M/H ratio, whereas the presence of intestinal metaplasia does not appear to influence the M/H ratio. These observations are consistent with the concept that the tissue from which the cancer arose may possess a pre-malignant biochemical lesion.