Next step of invasion: the Asian clam Corbicula fluminea (O. F. Müller, 1774) (Bivalvia: Cyrenidae) colonises smaller sandy rivers in Poland

This contribution presents a new observation of Corbicula fluminea (O. F. Müller) in Poland, found in 2021 in the Nida River, 40 km north of the nearest known locations. No species of the genus Corbicula has been previously recorded in the Nida, continuously explored for freshwater mussels since 2019. Live specimens were found in 20% of the collected sediment samples. The presence of young clams suggests that the population may be expanding rapidly through active movement or passive downstream drift. The clam was most likely introduced to the Nida by anglers as bait, but other possible pathways (e.g. transfer by kayaks or waterfowl, releases by aquarists) and the species’ impact on invaded ecosystems and native bivalves are discussed.

Mowing in agri-environmental schemes (AES) and rare species of Vertigo snails: hope for grasslands but a threat to snails

Four Vertigo species are covered by special forms of protection under Annex II of the Habitats Directive. The habitats of these snails are currently rare in Europe. Since typical conservation practices are ineffective for this ecosystem, support mechanisms for measures maintaining biodiversity have been incorporated into agriculture in the form of agri-environmental schemes (AES). However, an inappropriately designed AES may threaten the survival of populations of globally endangered species such as Vertigo moulinsiana (Dupuy) as mowing and swath removal dates coincide with the snails’ activity period in the upper parts of the mown plants, the majority of their population will be removed from the area along with the harvested swath. In addition, mowing instantaneously and radically alters the habitat’s microclimate. The policy of mowing the total area thus leads to unprecedented habitat homogenisation across the landscape, especially when machine mowers are used. In the case of V. moulinsiana, the best approach would be not to mow the whole area but to leave a part unmown where these snails could live unhindered. Instead of machines, traditional mowing could be implemented, which entails cutting at a greater height above the sedge clump level. This would not destroy the tussock structure and would allow the habitat to recreate itself. In combination with the designation of unmown refuges, the effects of this approach could be quite beneficial to the snails.

Blood parasites shape extreme major histocompatibility complex diversity in a migratory passerine

Pathogens are one of the main forces driving the evolution and maintenance of the highly polymorphic genes of the vertebrate major histocompatibility complex (MHC). Although MHC proteins are crucial in pathogen recognition, it is still poorly understood how pathogen-mediated selection promotes and maintains MHC diversity, and especially so in host species with highly duplicated MHC genes. Sedge warblers (Acrocephalus schoenobaenus) have highly duplicated MHC genes, and using data from high-throughput MHC genotyping, we were able to investigate to what extent avian malaria parasites explain temporal MHC class I supertype fluctuations in a long-term study population. We investigated infection status and infection intensities of two different strains of Haemoproteus, that is avian malaria parasites that are known to have significant fitness consequences in sedge warblers. We found that prevalence of avian malaria in carriers of specific MHC class I supertypes was a significant predictor of their frequency changes between years. This finding suggests that avian malaria infections partly drive the temporal fluctuations of the MHC class I supertypes. Furthermore, we found that individuals with a large number of different supertypes had higher resistance to avian malaria, but there was no evidence for an optimal MHC class I diversity. Thus, the two studied malaria parasite strains appear to select for a high MHC class I supertype diversity. Such selection may explain the maintenance of the extremely high number of MHC class I gene copies in sedge warblers and possibly also in other passerines where avian malaria is a common disease.

On the reintroduction of the endangered thick-shelled river mussel Unio crassus: The importance of the river's longitudinal profile

Freshwater mussels of the order Unionida provide important ecosystem functions and services. Unfortunately, some previously widespread species are now seriously endangered. To restore the historical range of the population of Unio crassus in the Biała River, southern Poland, the species was reintroduced into a series of 'stepping stones' joining two remnant populations. During the first phase of the study, the relationships between the abundance of U. crassus, physical habitat, and water quality were studied to assess reintroduction potential. In general, chemical water quality improved upstream from the existing population, favouring the decision for reintroduction, whereas morphological variables worsened. Mussel abundance was correlated negatively with the elevation and slope of channel, organic matter contents, and pH (exceeding 8.0), but positively with silt presence, water conductivity, and concentrations of HCO₃^-, Ca²⁺, and NO₃^-. During the second phase, adult individuals were introduced into one type of functional habitat-marginal channel sectors with still water and fine sediment. Despite the initial very high rate of reproduction in some parts of the upper reach of the river, the juveniles were ultimately recruited only in the lower part of the restored range, resulting in a very rapid change in recruitment at a channel slope of 1.8‰. Recruitment was positively related to silt content, conductivity, and Ca²⁺ and HCO₃^- ions, negatively to channel elevation and slope, and water pH. The host fish species showed no correlation with abiotic habitat features within the studied reach. These results imply that most of the habitat traits related to U. crassus occurrence depended on the river's longitudinal profile, not on the chemical water quality, and that final success of introduction should be evaluated after several years.

Extreme MHC class I diversity in the sedge warbler (Acrocephalus schoenobaenus); selection patterns and allelic divergence suggest that different genes have different functions

Background

Recent work suggests that gene duplications may play an important role in the evolution of immunity genes. Passerine birds, and in particular Sylvioidea warblers, have highly duplicated major histocompatibility complex (MHC) genes, which are key in immunity, compared to other vertebrates. However, reasons for this high MHC gene copy number are yet unclear. High-throughput sequencing (HTS) allows MHC genotyping even in individuals with extremely duplicated genes. This HTS data can reveal evidence of selection, which may help to unravel the putative functions of different gene copies, i.e. neofunctionalization. We performed exhaustive genotyping of MHC class I in a Sylvioidea warbler, the sedge warbler, Acrocephalus schoenobaenus, using the Illumina MiSeq technique on individuals from a wild study population.

Results

The MHC diversity in 863 genotyped individuals by far exceeds that of any other bird species described to date. A single individual could carry up to 65 different alleles, a large proportion of which are expressed (transcribed). The MHC alleles were of three different lengths differing in evidence of selection, diversity and divergence within our study population. Alleles without any deletions and alleles containing a 6 bp deletion showed characteristics of classical MHC genes, with evidence of multiple sites subject to positive selection and high sequence divergence. In contrast, alleles containing a 3 bp deletion had no sites subject to positive selection and had low divergence.

Conclusions

Our results suggest that sedge warbler MHC alleles that either have no deletion, or contain a 6 bp deletion, encode classical antigen presenting MHC molecules. In contrast, MHC alleles containing a 3 bp deletion may encode molecules with a different function. This study demonstrates that highly duplicated MHC genes can be characterised with HTS and that selection patterns can be useful for revealing neofunctionalization. Importantly, our results highlight the need to consider the putative function of different MHC genes in future studies of MHC in relation to disease resistance and fitness.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-017-0997-9) contains supplementary material, which is available to authorized users.

Prostaglandins in stallion semen

The purpose of the experiment was to obtain preparatory information about the presence of prostaglandins in semen collected from various types of horses after different periods of sexual rest. Semen was collected with an artificial vagina. Prostaglandin-like activity was estimated by the bioassay procedure described by Vane (1). Results are expressed in ng/ml PGE(2) of seminal plasma. The total concentration of prostaglandins in the full ejaculate averaged 43.73 +/- 4.93 ng/ml of plasma while the total amount of prostaglandins in the ejaculate was 1076 ng. Taking into consideration the period of sexual rest in the stallion, statistically significant differences were found in the prostaglandin level in the semen of all the stallions.

Basal and postprandial gut peptides affecting food intake in lean and obese pregnant women

Maternal obesity has been reported as a risk factor for various maternal and fetal complications. The aim of the present study was to examine the patterns of basal and postprandial plasma concentrations of certain gut hormones affecting food intake such as acylated ghrelin, peptide YY(3-36) (PYY(3-36)), cholecystokinin (CCK), insulin and glucose in pregnant women with varying body mass gain during physiological pregnancy. The study included 34 women with singleton pregnancies in the 2(nd) trimester of gestation. The examined pregnant women were divided into 4 groups; I. control pregnancy (CP) with weight gain below 0.5 kg/week; II. overweight low weight gain <1 kg/week (OLWG), III. overweight high weight gain >1 kg/week (OHWG); morbidly obese pregnant with weight gain >1.5 kg/week (MOP). The basal acylated-ghrelin levels in MOP subjects were significantly higher than those in CP and no usual suppression of acylated ghrelin after the meal observed in CP as well as in OLWG and OHWG was found in MOP women. Basal PYY(3-36) plasma levels were similar in CP, OLWG and OHWG but in MOP was significantly reduced and no significant increase in hormone level, typically observed in CP, was detected after a meal in overweight or obese women studied. The fasting CCK and C-reactive protein (CRP) levels in MOP subjects were significantly higher than those in CP and other overweight women. In conclusion, we found that pregnant women with overweight and obesity exhibit significant changes in fasting and postprandial gut hormones affecting food intake such as acylated ghrelin, PYY(3-36) and CCK as well as in CRP and these changes might contribute, at least in part, the development of obesity in pregnancy.

Variable effect of ghrelin administration on pancreatic development in young rats. Role of insulin-like growth factor-1

Ghrelin, an endogenous ligand of the growth hormone secretagogue receptor, has been primarily isolated from the human and rat stomach. Ghrelin has been shown to stimulate appetite and fat deposition in adult rats and humans. The aim of this study was to investigate the effect of ghrelin administration on pancreatic growth in suckling, weaned and peripubertal seven week old rats. Rats were treated with saline or ghrelin (4, 8 or 16 nmol/kg/dose) intraperitoneally twice a day: suckling rats were treated for 7 or 14 days starting from the first postnatal day, three week old weaned rats and seven weeks old rats were treated for 5 days. Treatment with ghrelin did not affect animal weight in suckling or weaned rats, whereas in young seven week old rats, ghrelin caused a significant increase in body weight. Ghrelin decreased food intake in weaned rats; whereas in seven week old rats, food intake was enhanced. In suckling rats, ghrelin decreased the pancreatic weight, pancreatic amylase content, DNA synthesis and DNA content. In contrast, ghrelin increased pancreatic weight, DNA synthesis, DNA content and amylase content in weaned or young seven week old rats. Pancreatic blood flow was not affected by ghrelin in any group of rats tested. Ghrelin increased serum level of growth hormone in all rats. This effect was weak in suckling rats, higher in weaned and the highest in seven week old animals. Ghrelin did not affect serum level of insulin-like growth factor-1 (IGF-1) in suckling rats. In weaned and in seven week old rats, treatment with ghrelin caused increase in serum level of IGF-1. We conclude that ghrelin reduces pancreatic growth in suckling rats; whereas in weaned and young seven week old animals, treatment with ghrelin increases pancreatic growth. This biphasic effect of ghrelin in young animals on pancreatic growth seems to be related to age-dependent changes of the release of anabolic IGF-1.

Association of the presence of Helicobacter pylori in the oral cavity and in the stomach

Helicobacter pylori is a gram-negative, microaerophilic rod-shaped bacteria that lives beneath the gastric mucous layer, on the surface of epithelial cells. Stomach infection with this organism causes inflammation of the gastric mucosa, which can lead to gastritis, duodenal or gastric ulcer and even in rare cases to gastric carcinoma or MALT lymphoma. Approximately 50% of the world's population is believed to be infected with H. pylori. Most infections is probably acquired in childhood, but the exact route of transmission is unknown. It has been speculated that dental plaque might harbour Helicobacter pylori and, therefore, might be a source of gastric infection. In order to address this issue we studied the relationships between oral and gastric infections with H. pylori in 100 subjects.

METHODS

Gastric H. pylori infection was determined by (13)C-urea breath test (UBT) and the presence of the bacteria in oral cavity was monitored by the culture from the saliva and from dental plaque.

RESULTS

H. pylori was found in the stomach in 51% of studied individuals, while oral H. pylori was found in 54% (in saliva) and in 48.3% (in gingival pockets), the difference was not statistical significant (p=NS). Interestingly, anti-Hp IgA was found in 84% of studied individuals. No relationship was found between the presence of the bacteria in the oral cavity and the H. pylori gastric infection. 54.9% of subjects with stomach infection showed concomitant presence of H. pylori in saliva. 52.3% of examined subjects with negative UBT-test revealed the presence of H. pylori in culture from the saliva. The X(2) value of relationship between UBT and culture H pylori in saliva was 0.029 (p=0.9). Similarly, no relationship was found between the presence of H. pylori in the stomach and in the dental plaque (X2=0.6); p=0.4). As expected, the presence of H. pylori in the dental plaque was significantly correlated with the presence of bacteria in the saliva (X2=18.4; p=0.0002). We also compared the presence of H. pylori in the saliva of patients with and without teeth. The cultured H. pylori was found in 63.7% of patients without teeth and in 52.9% of patients with teeth. This indicates that the presence of teeth does not seem to affect the occurrence of H. pylori in saliva. We conclude that oral activity contamination with of H. pylori occurs at similar degree to that in the stomach. However, there was no significant correlation between the occurrence of H. pylori in the stomach and in the oral cavity indicating that other factors, like susceptibility to infection due to acid environment in the stomach may be the major factor in gastric infection with that bacteria, while oral cavity may serve only as transient food-related contamination without clear relation to gastric infection.

Helicobacter pylori, non-steroidal anti-inflammatory drugs and smoking in risk pattern of gastroduodenal ulcers

BACKGROUND

Helicobacter pylori, NSAID and cigarette smoking are major risk factors for gastroduodenal ulcers. However, the results of studies on the interaction between these factors on ulcerogenesis are controversial. This study was designed to examine the association between gastroduodenal ulcers and H. pylori infection, NSAID use, smoking and age.

METHODS

5967 dyspeptic patients underwent 13C-urea breath test (UBT) and upper endoscopy, while age and dyspeptic symptoms were reported.

RESULTS

Out of 5967 patients, 31.8% were ulcerated; 9.2% had gastric, 17.2% duodenal and 5.4% both gastric and duodenal ulcers. H. pylori was found in 72.5% of gastric ulcer patients, in 83.6% of duodenal ulcer patients, in 76.9% of gastroduodenal ulcer patients and in 64.8% of dyspeptic patients. The gastric, duodenal and gastroduodenal ulcers were related to H. pylori significantly and the respective ORs were: 1.44, 2.77 and 1.81. NSAID alone was used by 6.2%-12.7% of ulcer patients, tending to raise only the risk of gastric ulcer but reducing that of duodenal and gastroduodenal ulcers. The H. pylori prevalence was significantly higher in smokers (76%) than in non-smokers (67%) and the ulcer risk was also significantly higher in smokers than in non-smokers. About 20% of ulcers were 'idiopathic', i.e. without NSAID and H. pylori and the ratio of these ulcers to all ulcers significantly increased during the 5 years of the study.

CONCLUSIONS

Based on multivariable logistic regression analysis we conclude that: 1) H. pylori infection, NSAID use, smoking and age play major roles in the pathogenesis of peptic ulcerations; 2) there is a negative interaction between H. pylori and NSAID on duodenal ulcers, suggesting that H. pylori reduces the development of these ulcers in NSAID users, and 3) about 20% of peptic ulcers in the Polish population are unrelated to H. pylori and NSAID use (idiopathic ulcers).

Molecular basis of colorectal cancer - role of gastrin and cyclooxygenase-2

BACKGROUND

Tumors arising in the colorectal area have worldwide distribution and concern mostly older population being attributed to genetic, dietary and hormonal factors but most recently also to infection with Helicobacter pylori (HP). Both, HP discovery and molecular biology of colorectal cancer have been recently considered as two of ten greatest advances of gastroenterology at the dawn of 3rd millenium but little information is available regarding the relationship between the HP and colorectal cancer. Since HP infection is usually accompanied by an increase in plasma level of gastrin, which is also recognized as a trophic hormone for the colonic epithelium and a potent mitogen capable to induce cyclooxygenase-2 (COX-2), we decided 1) to compare the seroprevalence of HP, its cytotoxic protein, CagA, and cytokines (TNFalpha, IL-1beta and IL-8) in colorectal cancer patients, before and after removal of cancer, with those in age- and gender-matched controls; 2) to determine the gene expression of gastrin and gastrin receptors (CCK(B)-R) in colorectal cancer tissue, 3) to assess the plasma levels and tumor tissue contents of gastrin, 4) to examine the mRNA expression of cyclooxygenase COX-1 and COX-2 cancer tissue and intact colonic mucosa.

MATERIAL AND METHODS

The trial material included 80 patients with colorectal cancers and 160 age- and gender-matched controls. Anti-HP IgG, anti-CagA IgG seroprevalence and cytokine levels were estimated by ELISA tests. Gene expressions of gastrin, CCK(B)-R, COX-1, COX-2 and Bax and Bcl2 was examined using RT-PCR, while gastrin was measured by RIA.

RESULTS

The HP IgG seroprevalence, especially that expressing CagA, was significantly higher in colorectal cancer patients than in controls and did not change one week after tumor resection while plasma cytokines were significantly reduced after this operation. Gastrin and CCK(B)-R mRNA were detected in the cancer tissue and the resection margin and similarly COX-2 mRNA was expressed in most of cancers and their resection margin but not in intact colonic mucosa where only COX-1 was detected. The colorectal cancer tissue contained several folds more immunoreactive gastrin than cancer resection margin and many folds more than the intact colonic mucosa.

CONCLUSIONS

1) Colorectal carcinoma and its resection margin overexpress gastrin and receptors for gastrin (CCK(B)-R), and COX-2; 2) here, we propose that an increased plasma level of gastrin should be considered as suitable biomarker of colorectal cancer, 3) HP infection may contribute to colonic cancerogenesis by enhancing expression of gastrin and COX-2, they may account for stimulation of the tumor growth, angiogenesis and reduction in apoptosis as evidenced an increased ratio of mRNA expression for anti-apoptotic Bcl2 over proapoptotic Bax proteins and 4) HP positive patients who develop colorectal cancer should be subjected to the HP eradication; this is expected to reduce hypergastrinemia and to attenuate COX-2 expression. Our final conclusion would be: treatment of patients with colorectal cancer with COX-2 selective inhibitors now gained a strong support as a preventive measure.

Leptin in the control of gastric secretion and gut hormones in humans infected with Helicobacter pylori

BACKGROUND

Leptin, a protein product of obese gene expressed primarily by adipocytes, provides feedback information on the size of energy stores to central OB receptors controlling the food intake, energy expenditure and body weight homeostasis. It has recently been detected in the rat stomach, especially after cholecystokinin (CCK) administration and in human stomach infected with Helicobacter pylori, but its role in gastric secretory functions in humans has not been revealed. This study was designed to determine the involvement of leptin in the control of basal, CCK- and meal-induced gastric H+ secretion and plasma gastrin and CCK levels in humans before and after an eradication of H. pylori.

METHODS

Two groups (A and B) of subjects were used; group A (n = 7), for comparison of the effects of CCK and leptin on basal gastric H+ and plasma hormone (leptin, gastrin and CCK) levels, and group B (n = 6), for studies on the involvement of leptin in gastric secretory and plasma hormonal responses to vagal stimulation and gastric peptone meal before and after H. pylori eradication.

RESULTS

In H. pylori-positive subjects, CCK (12-200 pmol kg(-1) h(-1)) given i.v. caused a dose-dependent increase of gastric H+ accompanied by a dose-dependent rise in plasma CCK and leptin levels. In contrast, leptin administered i.v. in graded doses (5-80 pmol kg(-1) h(-1)) resulted in a gradual inhibition of basal gastric H+ secretion and in adose-dependent increment in plasma leptin accompanied by an increase in plasma gastrin without alteration of plasma CCK level. Following eradication of H. pylori by 1-week triple therapy in group B patients, the infusion of CCK produced a significantly smaller increase in gastric H+ secretion and significantly smaller rise in plasma leptin as compared to those before the eradication. Cephalic phase stimulation of gastric secretion induced by modified sham-feeding in group B H. pylori-positive subjects increased gastric H+ secretion to about 40% of pentagastrin maximum without affecting plasma leptin, gastrin, or CCK level, while gastric peptone meal resulted in the increase in gastric H+ response reaching about 70% of pentagastrin maximum accompanied by a marked rise in plasma leptin, gastrin and CCK. The treatment with a standard dose of leptin (20 pmol kg(-1) h(-1)) failed to affect sham-feeding-induced gastric H+ secretion but reduced significantly the peptone meal-stimulated H+ secretion, while raising plasma gastrin in response to this meal. Plasma CCK under basal conditions and after sham-feeding was not affected, but plasma CCK response to gastric meal was significantly reduced by leptin infusion. Eradication of H. pylori did not affect basal or sham-feeding-induced H+ secretion but resulted in a significant fall in gastric meal-induced H+ and plasma leptin, gastrin and CCK levels.

CONCLUSIONS

1) The gastric meal and CCK enhance the release of leptin in H. pylori-positive patients and this leptin is capable of inhibiting basal and meal-stimulated gastric H+ secretion, while raising plasma gastrin and reducing the plasma CCK levels, and 2) the eradication of H. pylori reduces the postprandial gastric H+ and plasmagastrin responses as well as the release of leptin in response to CCK and meal.

Cancerogenesis in Helicobacter pylori infected stomach--role of growth factors, apoptosis and cyclooxygenases

BACKGROUND

Epidemiological and animal studies demonstrated a link between gastric cancer (GC) or mucosal associated lymphoid tissue (MALT) lymphoma and chronic infection with Helicobacter pylori (H. pylori). The exact mechanism responsible for the development of GC and MALT-lymphoma in H. pylori-infected patients still remains obscure. This report is designed to overview the molecular biology, especially the gene expression and histochemical manifestation of gastrin and other growth factors such as transforming growth factor alpha (TGF alpha) and hepatocyte growth factor (HGF) in the GC before and after eradication of H. pylori. Furthermore, gene expression of cyclooxygenase-1 (COX-1) and COX-2 and apoptosis-related proteins such as Bax and Bcl-2 are discussed.

MATERIAL AND METHODS

The findings originate from two series of patients; Series I involving 337 GC patients and 400 age- and gender-matched controls and series 2 including 20 MALT-lymphoma patients and 40 matched controls.

RESULTS

An overall H.pylori-seropositivity reached about 80% in GC and about 90% in MALT-lymphoma, significantly higher than in non-cancer controls (60%). The prevalence of CagA-positive strains was about twice as high (about 70%) in GC and MALT-lymphomas as in sex- and age-matched controls. Expression of gastrin was detected in antrum of all tested patients but also in majority (90%) of GCs and MALT-lymphomas tumor tissue. HGF and TGF alpha were expressed more frequently in GC tissue than in normal fundic mucosa. COX-1 was similarly expressed in GC and MALT as in intact mucosa, while COX-2 mRNA was detected only in tumor tissue, being attenuated by H.pylori eradication in GC and abolished by this therapy in MALT-lymphoma. The plasma levels of alpha-amidated gastrin in GC and MALT were several folds higher than in controls. Gene expression of bcl-2 was detected in all, while bax--only in about 50% of GC samples.

CONCLUSIONS

Infection with H. pylori, especially that expressing CagA-positivity, is primum movens in developing GC and MALT-lymphoma and the upregulation of growth factors, particularly of gastrin, and COX-2 and dysregulation of the Bax/Bcl-2 system seem to contribute to gastric cancerogenesis.

Comparison of nitric oxide-releasing NSAID and vitamin C with classic NSAID in healing of chronic gastric ulcers; involvement of reactive oxygen species

BACKGROUND

Nonsteroidal anti-inflammatory drugs such as aspirin (ASA) are known to induce gastric mucosal damage including bleeding, ulceration and perforation in humans and experimental animals. These adverse effects of ASA were originally attributed to the inhibition of cyclooxygenase and the deficiency of endogenous prostaglandins induced by this drug but the role of reactive oxygen species (ROS), lipid peroxidation and antioxidizing mechanism in the pathogenesis of ASA damage has been little studied. New class of nitric oxide (NO)-releasing nonsteroidal anti-inflammatory drugs was shown to inhibit cyclooxygenase and prostaglandin generation without causing mucosal damage but it remains unknown whether these agents affect the healing process of chronic gastric ulcers.

MATERIAL AND METHODS

In this study the effect of NO-releasing aspirin (NO-ASA) and was compared with that of native aspirin applied with or without vitamin C on the healing of acetic acid ulcers. The area of gastric ulcer was determined by planimetry, the gastric blood flow (GBF) at ulcer margin was measured by H2 gas clearance method and mucosal release of ROS was quantified by measuring the chemiluminescence before and after the treatment with ASA or NO-ASA alone and ASA combined with vitamin C. The plasma antiinflammatory cytokine such as IL-1b and oxygen radical-mediated lipid peroxidation was measured in the ulcerated gastric mucosa of ASA and NO-ASA-treated animals.

RESULTS

ASA delayed significantly ulcer healing and this effect was accompanied by a marked increase in the chemiluminescence, lipid peroxidation and the fall in the GBF at ulcer margin. Vitamin C attenuated significantly both the ASA-induced gastric damage and accompanying fall in the GBF at ulcer margin and the rise in the chemiluminescence and reversed the ASA-induced lipid peroxidation. In contrast, NO-ASA failed to affect healing of gastric ulcers and failed to produce the rise in the plasma IL-1b levels and the increase of lipid peroxidation as compared to those recorded in ASA-treated animals.

CONCLUSIONS

1) ROS-induced enhancement in lipid peroxidation plays an important role in the mechanism of gastric damage induced by ASA, 2) vitamin C attenuates the deleterious effect of ASA on ulcer healing due to its antioxidizing activity by mechanism involving preservation of gastric microcirculation and attenuation of lipid peroxidation and cytokine release and 3) coupling of NO to aspirin fails to delay the ulcer healing suggesting that NO might compensate for prostaglandin deficiency induced by NSAID.

Involvement of cyclooxygenase-derived prostaglandin E2 and nitric oxide in the protection of rat pancreas afforded by low dose of lipopolysaccharide

Prostaglandins (PG), the products of arachidonate metabolism through cyclooxygenase (COX) pathway, protect the pancreas from the acute damage. The existence of two isoforms of COX was documented including: COX-1, present in normal tissues and COX-2, expressed at the site of inflammation, such as induced by bacterial lipopolysaccharide (LPS). Pretreatment with low dose of LPS and activation of nitric oxide (NO) synthase (NOS) has been shown to prevent the injury caused by caerulein-induced pancreatitis (CIP) in the rat. The aim of this study was to investigate the role of COX-1 and COX-2 in the LPS-induced protection of the pancreas against CIP and the involvement of NOS in the activation of COX-PG system in the rats with CIP. CIP was produced by subcutaneous (s.c.) infusion of caerulein (5 microg/kg-h for 5 h) to the conscious rats. Protective dose of LPS, from Escherichia coli, (1 mg/kg) was given intraperitoneally (i.p.) 15 min prior to the start of CIP. Nonselective inhibitor of COX; indomethacin (5 or 10 mg/kg), selective inhibitor of COX-1: resveratrol, or a highly selective inhibitors of COX-2: rofecoxib or NS-398 (2 or 10 mg/kg) were injected i.p. 15 min prior to the administration of LPS. COX-1 or COX-2 mRNA was determined by reverse transcription-polimerase chain reaction (RT-PCR) in the pancreatic tissue. Pancreatic blood flow (PBF) was measured by a laser Doppler flowmetry. PGE2 content in the pancreas was measured by radioimmunoassay. CIP was manifested by an increase of pancreatic weight and plasma amylase activity (by 500% and 700%, respectively) and it was confirmed by histological examination. CIP slightly increased pancreatic PGE2 generation (by 12%) and diminished PBF (by about 40%). LPS (1 mg/kg i.p.), given prior to the start of CIP, increased PGE2 generation in the pancreas (by 45%), reversed the histological manifestations of pancreatitis, reduced the rise in amylase blood level and improved PBF. Administration of nonselective inhibitor of COX; indomethacin (5 or 10 mg/kg i.p.) prior to the injection of LPS abolished its protective effects on CIP and reduced pancreatic PGE2 generation. Selective inhibitor of COX-1; resveratrol (10 mg/kg i.p.) given prior to the injection of LPS reversed its protective effects against CIP. Pretreatment with a selective inhibitors of COX-2: rofecoxib or NS-398 (10 mg/kg) attenuated LPS-induced pancreatic protection in the CIP rats. COX-1 expression was detected in the intact pancreas and was not significantly changed by CIP, LPS, indomethacin, NS-389 and their combination, while COX-2 mRNA expression appeared in the pancreas of ratssubjected to CIP and was significantly increased after LPS injection to these rats. Addition of selective COX-2 inhibitor; NS-389, or nonselective inhibitor of COX; indomethacin, enhanced COX-2 mRNA expression in the rats with CIP pretreated with LPS. Pretreatment of the rats with inhibitor of NOS; L-NNA (20 mg/kg i.p.), given together with LPS, 15 min prior to the start of caerulein overstimulation, resulted in complete reversion of LPS-induced pancreatic protection and decreased PGE2 generation stimulated by LPS. Addition to L-NNA of the substrate for NOS; L-arginine (100 mg/kg i.p.), restored pancreatic protection afforded by low dose of LPS and increased pancreatic PGE2 level in the rats with CIP. We conclude that: 1. increased pancreatic PGE2 generation, induced by low dose LPS pretreatment, contributes to the pancreatic resistance to acute damage produced by caerulein overstimulation and 2. the NO-system is involved in above stimulation of PGE2 generation and pancreatic protection against acute damage.

Water extracts of Helicobacter pylori suppress the expression of histidine decarboxylase and reduce histamine content in the rat gastric mucosa

BACKGROUND

Acute Helicobacter pylori (Hp) infection in humans may be associated with markedly reduced gastric acid secretion, but the mechanism of this hypochlorhydria has not been fully explained.

AIMS

This study was designed to investigate how water extracts (WE) of Hp applied on rat gastric mucosa affect gastric secretion and mucosal histamine concentration as well as the gene expression for histamine decarboxylase (HDC), the key enzyme converting histidine to histamine and for interleukin-1beta (IL-1beta), the important proinflammatory cytokine.

MATERIALS AND METHODS

Wistar rats were surgically equipped with small cannulas to form gastric fistulas (GF). Four weeks after formation of GF, rats received either saline (control group) or WE obtained from type I Hp strain expressing CagA/VacA proteins and from type II Hp strain negative for CagA/VacA. Hp-WE was applied intragastrically (i.g.) in a volume of 1 ml at days 0, 2, 4 and 6 (total 4 times). At days 7 and 14, the secretory tests were performed during which basal gastric acid and pepsin secretion was examined and acid and pepsin outputs were measured. After secretory tests, the rats were sacrificed, the stomachs removed and the damage to the gastric mucosa was assessed by measuring the lesion area planimetrically and by histology, the gene expression in gastric mucosa for HDC and interleukin-1beta (IL-1beta) was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blot. Additionally, somatostatin concentration in gastric juice, gastric mucosal histamine content and plasma gastrin and IL-1beta levels were determined using radioimmunoassay (RIA).

RESULTS

Administration of Hp-WE failed to induce gross mucosal damage but microscopic examination revealed partial denudation of gastric surface epithelium without causing deep necrosis. In secretory tests, Hp-WE produced marked hypochlorhydria but type I Hp-WE induced significantly stronger inhibition of acid and pepsin secretion than type II Hp-WE, both at days 7 and 14. Both, type I and type II Hp-WE suppressed significantly the gene expression for HDC mRNA and lowered significantly gastric mucosal histamine content as compared to respective values in vehicle-treated control gastric mucosa. Furthermore, Hp-WE, resulted in a significant increase in expression of IL-1beta mRNA and a significant fall in luminal somatostatin concentration as well as a insignificant elevation of plasma gastrin level, the type I Hp-WE being more effective in these alterations than type II Hp-WE.

CONCLUSIONS

(1) Ability of Hp-WE to induce superficial damage, the reduction in HDC mRNA and accompanying fall in gastric histamine release, contribute, at least in part, to marked hypochlorhydria observed in the stomach exposed to repeated Hp-WE treatments, and (2) the deleterious effect of Hp-WE on the gastric mucosa involves an impairment of gastrin-somatostatin link possibly resulting from the action of Hp-derived toxins and the induction in mucosal cells of proinflammatory cytokine such as IL-1beta.

Helicobacter pylori, gastrin and cyclooxygenase-2 in lung cancer

INTRODUCTION

Tumors arising in the lungs are in over 90% bronchogenic carcinomas that have been attributed predominantly to tobacco smoking, asbestos or air pollution but little is known about endogenous factors that could facilitate their development and invasiveness. The lungs originate embryologically from the same endoderm cells which form the epithelia lining the digestive tract, where gastrin is the major proliferative stimulus.

AIMS

Since lung cancer patients were recruited mostly among smokers, who also have been found to exhibit significantly higher infection rate of Helicobacter pylori (HP) infection than non-smokers and, as since the HP-infected subjects show enhanced plasma levels of gastrin, we decided 1) to compare the seroprevalence of HP and the expression of its cytotoxin, CagA, in lung cancer patients with those in the age- and gender-matched controls without cancer: 2) to determine the gene expression for gastrin and its receptors (CCKB-R) in lung cancer, 3) to assess the gastrin levels in plasma bronchial lavage and in tumor tissue and 4) to examine the expression of cyclooxygenase (COX)-1 and COX-2 in cancer tissue resection margin and intact bronchial mucosa.

MATERIAL AND METHODS

The trial material included 50 patients with lung carcinoma and 100 age- and gender-matched controls. Anti-HP and anti-CagA IgG seroprevalence was estimated by specific antisera using ELISA tests. Gene expression of gastrin, CCKB-R, COX-1 and COX-2 was examined using RT-PCR, while gastrin was measured by specific RIA.

RESULTS

The seroprevalence of HP, especially that expressing CagA, is significantly higher in lung cancers than in healthy controls. Both gastrin and CCKB-R mRNA were detected in the cancer tissue and at the resection margin and similarly COX-2 mRNA was expressed in most cancers and resection margin but not in bronchial mucosa where only COX-1 was found. The lung cancer tissue and resection margin contained many folds larger amounts of immunoreactive gastrin than intact bronchial mucosa.

The effects of ammonia on pancreatic enzyme secretion in vivo and in vitro

BACKGROUND

Recent studies clearly demonstrate that Helicobacter pylori (H. pylori) infection of the stomach causes persistent elevation of ammonia (NH3) in gastric juice leading to hypergastrinemia and enhanced pancreatic enzyme secretion.

METHODS

The aim of this study is to evaluate the influence of NH4OH on plasma gastrin level and exocrine pancreatic secretion in vivo in conscious dogs equipped with chronic pancreatic fistulas and on secretory activity of in vitro isolated acini obtained from the rat pancreas by collagenase digestion. The effects of NH4OH on amylase release from pancreatic acini were compared with those produced by simple alkalization of these acini with NaOH.

RESULTS

NH4OH given intraduodenally (i.d.) in increasing concentrations (0.5, 1.0, 2.0, 4.0, or 8.0 mM/L) resulted in an increase of pancreatic protein output, reaching respectively 9%, 10%, 19%, 16% and 17% of caerulein maximum in these animals and in a marked increase in plasma gastrin level. NH4OH (8 x 0 mM/L, i.d.) given during intravenous (i.v.) infusion of secretin (50 pmol/kg-h) and cholecystokinin (50 pmol/kg-h) reduced the HCO3 and protein outputs by 35% and 37% respectively, as compared to control obtained with infusion of secretin plus cholecystokinin alone. When pancreatic secretion was stimulated by ordinary feeding the same amount of NH4OH administered i.d. decreased the HCO3- and protein responses by 78% and 47% respectively, and had no significant effect on postprandial plasma gastrin. In isolated pancreatic acini, increasing concentrations of NH4OH (10(-7)-10(-4) M) produced a concentration-dependent stimulation of amylase release, reaching about 43% of caerulein-induced maximum. When various concentrations of NH4OH were added to submaximal concentration of caerulein (10(-12) M) or urecholine (10(-5) M), the enzyme secretion was reduced at a dose 10(-5) M of NH4OH by 38% or 40%, respectively. Simple alkalization with NaOH of the incubation medium up to pH 8.5 markedly stimulated basal amylase secretion from isolated pancreatic acini, whereas the secretory response of these acini to pancreatic secretagogues was significantly diminished by about 30%. LDH release into the incubation medium was not significantly changed in all tests indicating that NH4OH did not produce any apparent damage of pancreatic acini and this was confirmed by histological examination of these acini.

CONCLUSIONS

1. NH4OH affects basal and stimulated pancreatic secretion. 2. The excessive release of gastrin may be responsible for the stimulation of basal pancreatic enzyme secretion in conscious animals, and 3. The inhibitory effects of NH4OH on stimulated secretion might be mediated, at least in part, by its direct action on the isolated pancreatic acini possibly due to the alkalization of these acini.

Helicobacter pylori and its eradication in rosacea

Rosacea is a common condition of unknown etiology usually accompanied by gastrointestinal symptoms and favorably responding to the treatment with antibiotics. This study was designed to examine the prevalence of gastric Helicobacter pylori (Hp) infection verified by 13C-UTB-test, CLO, Hp culture and serology (IgG) in patients with rosacea. Gastroduodenoscopy was combined with pentagastrin secretory test and antral and fundic biopsy samples were taken for histological evaluation (the Sydney system). Blood samples were also taken for the determination of plasma gastrin using RIA and plasma interleukin (IL)-8 and tumor necrosis factor alpha (TNFalpha) using ELISA. This study was performed in 60 patients, 31-72 year old, with visible papules and pustules associated with erythema and flushing on the face and on 60 age- and gender-matched patients without any skin diseases but with similar as in rosacea gastrointestinal symptoms but without endoscopic changes in gastroduodenal mucosa (non-ulcer dyspepsia - NUD). The Hp prevalence in rosacea patients was about 88 % as compared to 65% in control NUD patients. Among rosacea patients, 67% were cytotoxin associated gene A (CagA) positive, while in NUD patients only 32% were CagA positive. Rosacea patients showed gastritis with activity of about 2.1 in antrum and 0.9 in the corpus of the stomach while those with NUD only mild gastritis with activity of approximately 1.0) confined to the antrum only. Following initial examination, typical 1 wk anti-Hp therapy including omeprazole (20 mg bd.), clarithromycin (500 mg bd.) and metronidazol (500 mg bd.) was carried out. After eradication, 51 out of 53 treated rosacea patients became Hp negative. Within 2-4 weeks, the symptoms of rosacea disappeared in 51 patients, markedly declined in 1 and remained unchanged in 1 other subject. A dramatic reduction in activity of gastritis (to 0.3 in antrum and to 0.1 in corpus) was observed. Basal plasma gastrin decreased from 48 +/- 5 pM before to 17+/-3 pM after eradication, while pentagastrin-induced maximal (MAO) declined, respectively, from about 16.6 +/- 4.2 to 8.5 +/- 1.8 mmol/h. Plasma TNFalpha and IL-8 were reduced after the therapy by 72% and 65%, respectively. We conclude that: 1) Rosacea is a disorder with various gastrointestinal symptoms closely related to gastritis, especially involving the antrum mucosa, with Hp expressing cagA in the majority of cases and elevated plasma levels of TNFalpha and IL-8; 2) The eradication of Hp leads to a dramatic improvement of symptoms of rosacea and reduction in related gastrointestinal symptoms, gastritis, hypergastrinemia and gastric acid secretion; and 3) Rosacea could be considered as one of the major extragastric symptoms of Hp infection probably mediated by Hp-related cytotoxins and cytokines.

Helicobacter pylori associated gastric pathology

Helicobacter pylori (HP), undoubtedly, the most common world-wide infection plays an important role in pathogenesis of peptic ulcer. Proof for a causal role for HP in peptic ulcer rests in two major points; 1) the majority of ulcer patients are HP infected and the prevalence of this infection for both gastric ulcer (GU) and duodenal ulcer (DU) is much higher than for gender- and age-adjusted controls and 2) the cure of HP infection dramatically reduces ulcer recurrence. Conclusions regarding the mechanisms by which HP induces peptic ulcer are restricted mainly to studies observing the consequences of its eradication by antibiotics combined with gastric inhibitors or bismuth agents. Several specific virulence factors such as cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA) as well as other noxious substances including ammonia, lipopolysaccharide (endotoxin), platelet activating factor (PAF), nitric oxide (NO) and others have been implicated in gastritis and were found to be significantly more frequent in gastric cancer than in gender- and age-matched controls, especially in younger generation. Chronic inflammation, atrophic gastritis, intestinal metaplasia, impaired defense mechanisms combined with hypergastrinemia, deficiency of vitamin C in the stomach , excessive oxygen metabolites and epithelial cell proliferation have been associated with gastric cancer. This multi-step pathway originally proposed by Correa and his colleagues, long before the HP was discovered in the stomach, leads to cancer but may be reversed by eradication of HP. This is, however, a controversial issue because gastric atrophy and intestinal metaplasia may be also caused by other factors such as bile reflux, dietary irritants, and autoimmunity. The implication of HP in MALT-lymphoma is based on the observations that eradication of HP in early stage of low-grade of this tumor leads to complete remission. The significance of HP in non-ulcer dyspepsia remains questionable and requires further studies.

Role of Helicobacter pylori infection in extragastroduodenal disorders: introductory remarks

Numerous studies initiated by Warren and Marshall in 1982 confirmed the crucial role of H. pylori infection in the pathogenesis of gastritis, peptic ulcer and possibly also gastric cancer leading to reappraisal of fundamental concept of gastric pathophysiology. These topics were covered, in part, by our previous H. pylori-related symposium I (1995), II (1997) and III (1999) organized in Cracow. H. pylori is one of the most frequent causes of gastroduodenal infection worldwide, resulting in the release of various bacterial and host dependent cytotoxic substances including ammonia, platelet activating factor (PAF), cytotoxins and lipopolysaccharides (LPS) as well as cytokines such as interleukins (IL)-1-12, tumor necrosis factor alpha (TNF(alpha), interferon gamma (INFgamma) and reactive oxygen species (ROS). Recently, several extradigestive pathologies have been linked to H. pylori infection including cardiovascular, cutaneous, autoimmune, esophageal and other diseases such as sideropenic anemia, growth retardation, extragastric MALT-lymphoma etc. The potential role of H. pylori infection in the pathogenesis of these extradigestive disorders has been based on facts that 1) local gastric inflammation may exert systemic effects, 2) chronic infection of gastric mucosa induces immune responses that are able to cause the lesions remote to primary site of infection and 3) H. pylori eradication improves the extradigestive disorders. The aim of present III International Symposium is to provide critical reviews based on personal experience and the available literature about extragastric manifestations of H. pylori infection. The ultimate goal of this symposium is to foster interdisciplinary research and exchange of opinion about the possible involvement of H. pylori in extradigestive pathologies.

Epidemiological study on Helicobacter pylori infection and extragastroduodenal disorders in Polish population

An association between Helicobacter pylori (H. pylori) infection and extragastroduodenal disorders (EGDD) is still not clear. The aim of the study was to investigate the relationship between H. pylori infection and the symptoms of coronary artery disease (CAD), facial dermatological changes (FDC), gastroesophageal reflux diseases (GERD), and periodontal diseases (PD) in Polish population. The study was performed between 1996-1999 year on 7,060 adult inhabitants of municipal area of Krakow (aged 18-76, mean 46.3 year; 55.8% female, 44.2% male): 2,204 subjects with EGDD and 4,856 without symptoms of EGDD. Each patient responded to a detailed questionnaire under supervision of medical staff. The H. pylori status was assessed non-invasively using urea breath test (UBT) with capsulated low-dose 13C-UBT (38 mg). Exclusion criteria were: recent H. pylori eradication, treatment with PPI, bismuth and/or antibiotics in the last 4 weeks. Four groups of cases with EGDD symptoms were selected. Within each group exclusively only one of studied symptoms was recorded. The study included 328, 138, 688, and 1,050 patients with CAD, FDC, GERD and PD, respectively. For each studied group an age and sex-matched asymptomatic controls were selected (897, 387, 1,083, and 2,489 control patients).

RESULTS

Overall H. pylori infection rate was 69,9% (in 71.4% of 2,204 cases and in 69.31% of 4,856 controls). In CAD group: 68% of 328 cases were H. pylori (+ve) vs. 70% H. pylori (+ve) of 897 controls. An association was not significant: OR = 0.93 (95% CI, 0.72-1.20). In 138 of FDC cases, 59% were H. pylori (+ve) vs. 71% H. pylori (+ve) in 387 controls showing the lack of positive association; OR = 0.60 (95% CI, 0.42-0.87). In GERD, 69% of 688 cases were H. pylori (+ve) vs. 73% of 1,083 H. pylori (+ve) controls and negative association was observed; OR=0.80 (95% CI, 0.65-1.00). In 1,050 of PD cases 75% were H. pylori (+ve) vs. 68% H. pylori (+ve) of 2,489 controls; positive association was significant; OR = 1.4 (95% CI, 1.16-1.68). We conclude that in the studied Polish population, no positive association exists between H. pylori positivity and CAD, FDC or GERD possibly due very high overall H. pylori infection rate. The only positive link observed between H. pylori infection and periodontal disease may reflect direct "in situ" H. pylori pathological action of H. pylori in oral cavity. It is not excluded that periodontal diseases may facilitate the H. pylori oro-gastric transmission and colonisation of the bacteria in the digestive tract.

Leptin in gastroprotection induced by cholecystokinin or by a meal. Role of vagal and sensory nerves and nitric oxide

Leptin, detected recently in the stomach, is a product of the ob gene released by cholecystokinin (CCK) and plays an important role in the control of food intake but its influence on gastroprotection against the damage caused by noxious agents has not been studied. This study was designed to compare the effects of leptin and cholecystokinin-8 (CCK-8) on gastric mucosal lesions induced by topical application of 75% ethanol or acidified aspirin. Four series of Wistar rats (A, B, C and D) were used to determine the effects of: (A) suppression of prostaglandin biosynthesis by indomethacin (5 mg/kg i.p.); (B) inhibition of nitric oxide (NO)-synthase by nitro-L-arginine methyl ester (L-NAME) (5 mg/kg i.v.); (C) blockade of sensory nerves by capsaicin (125 mg/kg s.c.) and (D) bilateral vagotomy, on the gastric lesions induced by intragastric (i.g.) application of ethanol with or without pretreatment with CCK-8, a known gastroprotective substance or leptin. CCK-8 (1-100 microg/kg i.p.) and leptin (0.1-50 microg/kg i.p.) dose dependently attenuated gastric lesions induced by 75% ethanol; the dose reducing these lesions by 50% being about 10 microg/kg and 8 microg/kg, respectively. The protective effects of CCK-8 and leptin were accompanied by a significant rise in gastric blood flow (GBF) and luminal NO concentration. Leptin was also effective to attenuate aspirin-induced damage and the accompanying fall in the GBF, whereas CCK-8 dose dependently worsened aspirin damage and failed to influence GBF. CCK (1-100 microg/kg i.p.), given in graded doses, produced a dose-dependent increase in the plasma leptin level and a rise of the expression of ob messenger RNA (mRNA) in gastric mucosa, the maximum being reached at a dose of 100 microg/kg. Pretreatment with CCK-8 (10 microg/kg i.p.) or with 8% peptone, that is known to stimulate CCK release, also produced a significant rise in plasma leptin levels and up-regulation of ob mRNA while reducing significantly the gastric lesions induced by 75% ethanol to the same extent as that induced by exogenous leptin (10 microg/kg i.p.). Indomethacin, which suppressed prostaglandin generation by approximately 90%, failed to influence leptin- or CCK-8-induced protection against ethanol, whereas L-NAME attenuated significantly CCK-8- and leptin-induced protection and hyperemia but addition to L-NAME of L-arginine, but not D-arginine, restored the protective and hyperemic effects of both hormones. The ob mRNA was detected as a weak signal in the intact gastric mucosa and in that exposed to ethanol alone but this was further enhanced after treatment with graded doses of CCK-8 or peptone meal applied prior to ethanol. We conclude that: (1) exogenous leptin or that released endogenously by CCK or meal exerts a potent gastroprotective action depending upon vagal activity, and involving hyperemia probably mediated by NO and sensory nerves but unrelated to endogenous prostaglandins; (2) leptin mimics the gastroprotective effect of CCK and probably mediates the protective and hyperemic actions of CCK in the rat stomach.

[Hormonal changes and secretion and stomach mucosal microstructure in the course of H. pylori in patients with duodenal ulcer]

We designed this study to follow exocrine, endocrine and microstructural changes in duodenal ulcer patients with H. pylori infection in the course and after quadruple eradication regimen. Quadruple therapy appeared to be highly effective method of both ulcer healing and H. pylori eradication. We observed enhanced regeneration of gastric mucosa in the course of treatment. Almost immediate decrease of plasma gastrin and increase of plasma somatostatin and EGF concentration in gastric juice were noticed.

[Endocrine and exocrine gastric mucosal secretion in the course of H. pylori eradication in patients with non-ulcer dyspepsia]

Microstructural, endo- and exocrine changes in gastric mucosa of Non-Ulcer Dyspepsia patients with H. pylori infection in the course of eradication has been studied. Before, during and after anti H. pylori therapy plasma gastrin and somatostatin levels, EGF and somatostatin concentration in gastric juice and basal and pentagastrin stimulated gastric acid secretion were measured. Moreover microstructure of gastric mucosa specimens has been studied. Maximal Acid Output initially higher in NUD patients than in healthy volunteers increased slightly in the course of eradication. Plasma gastrin decreased while EGF and somatostatin concentration in gastric juice increased. After treatment the ratio of patients with pronounced features (activity) of gastritis was significantly reduced.

Gastric mucosal expression and luminal release of growth factors in gastric carcinoma and duodenal ulcer patients before and after eradication of Helicobacter pylori

Epidemiological studies have consistently shown an association between infection of Helicobacter pylori (Hp) and duodenal ulcer (DU) and gastric cancer. The mechanism of the ulcerogenic effect of Hp has been related to excessive gastrin release, gastric acid hypersecretion and gastric metaplasia in duodenum. The implication of Hp in gastric carcinogenesis has not been explained. In this study, mucosal expression of EGF and TGF alpha and luminal release of EGF as well as basal and pentagastrin-stimulated acid secretion and plasma gastrin levels have been determined in healthy subjects, gastric carcinoma and DU patients. It was found that Hp positive DU patients show excessive gastrin release and gastric acid secretion combined with increased expression and luminal release of EGF and TGF alpha. These changes returned to normal values two years after the eradication of Hp. Gastric cancer patients also showed increased expression of EGF and TGF alpha and highly increased plasma gastrin but their gastric acid secretion was markedly reduced possibly due to atrophy of oxyntic mucosa. This study indicates that overexpression of growth factors in gastric mucosa may be implicated in the pathogenesis of both duodenal ulcer and gastric cancer and that Hp positive hypochlorhydric and hypergastrinemic patients may be predisposed to development of gastric cancer.

New approach to 13C-urea breath test: capsule-based modification with low-dose of 13C-urea in the diagnosis of Helicobacter pylori infection

This study was designed to evaluate a novel modification of the non-invasive capsule-based 13C-urea breath test (13C-UBT). 114 patients were tested for Helicobacter pylori (HP) infection with the use of only 38 mg 13C-urea administrated in solid capsulated form. Obtained results were compared with tissue based methods: histology and rapid urease test (CLOtest). Results of histology and/or CLOtest were considered as the gold standard for each patient. In addition, also capsule-based, micro-dose (37kBq) 14C-urea breath test (14C-UBT) was performed. With a cut-off for delta-over-base values of 5/1000 (i.e., 5 per mil), 13C-UBT results (measured by non-dispersive infrared spectroscopy, NDIRS) correlated highly significant with combined results for invasive methods i.e., CLOtest + histology score. Compared with histology, CLOtest, and the gold standard, the diagnostic values of the test were: sensitivity 97%, specificity 95%, with positive and negative predictive values about 90% and 98% respectively. The modified 13C-UBT test was found to be in full concordance with 14C-UBT; there was 100% agreement in the diagnostic classification of all positive (89) and negative (25) patients. Described modification of 13C-UBT showed that presented modification of 13C-UBT is an excellent, simple, low cost, non invasive, and safe diagnostic tool in HP detection and should be recommended particularly in cases when the use of radioactive urea is contraindicated.

Oral cavity as permanent reservoir of Helicobacter pylori and potential source of reinfection

Recent studies in developed countries showed that neither dental plaques nor dentures are important reservoir for Helicobacter pylori (Hp), whereas studies in developing countries revealed a high prevalence of Hp in dental plaques, though elsewhere the culture of bacterium or its DNA analysis by polymerase chain reaction in the material obtained from oral cavity were not successful. This study was designed to compare the incidence of Hp in oral cavity (saliva, dental plaques and gingival pockets) using Campylobacter-like organism (CLO) test and culture and in the presence of Hp in the stomach using 14C-urea breath test (UBT), CLO-test and culture (antral biopsy specimens). Hundred dyspeptic subjects with endoscopically normal gastro-duodenal mucosa and 55 symptomatic patients with active duodenal peptic ulcer (DU) were tested for the presence of Hp. Thirty of these DU patients were also examined for presence of Hp in oral cavity and the stomach just before the start and 4 weeks after the termination of one week triple therapy (Omeprazole 20 mg bd, Clarithromycin 500 mg bd and Tinidazole 500 mg bd) when the DU was found endoscopically healed. In the group of 100 dyspeptic subjects, the Hp was detected by CLO-test in saliva, dental plaques and gingival pockets in 84%, 100% and 100% of cases and by the culture in 55%, 88% and 100%, respectively. The presence of Hp, as determined by UBT in the stomach in these subjects was 60%. Using CLO-test and culture, all (100%) out of 55 DU patients, were found to be Hp positive in the oral cavity and in 95% in the stomach. Following one week triple therapy in 30 DU patients, the Hp was still detected in oral cavity by CLO-test in all patients (100%) and by culture in 27 patients (90%), whereas in the stomach, the Hp was found by UTB and culture only in one of these patients (97% Hp eradicated). We conclude that the Polish population including dyspeptic and DU patients, the mouth is permanent reservoir of Hp and that the successful Hp eradication from the stomach by systemic therapy fails the Hp status in the oral cavity that might be a potential source of gastric reinfection in these patients.

Microdose 14C-urea breath test in detection of Helicobacter pylori

Etiologic role for Helicobacter pylori (Hp) seems to be well established in gastric pathology. The high urease activity of Hp can be used to detect this bacterium by non-invasive urea breath tests (UBT). We validated the microdose version of the test in which 37 kBq 14C-urea is given orally in capsule. With the cut off value > 100 DPM as positive, UBT results correlated highly significant with combined results for invasive methods i.e. CLOtest + histology score. The reproducibility of the test was 100%. The results obtained for the breath test performed locally were almost identical with that read at remote laboratory. The data found for fasting and fed states of subjects agreed in 87%. When 14C-urea was confined in the mouth of both Hp positive and Hp negative patients UBT showed the presence of urease activity in the mouth cavity. 14C-urea capsule based breath test is highly reliable, safe, and reproducible for detection of Hp in the stomach. Results can be obtained within 15 min if a scintilation counter is nearby, or breath samples can be mailed to a testing laboratory for analysis.

One week treatment with omeprazole, clarithromycin and tinidazole or lansoprazole, amoxicillin and metronidazole for cure of Helicobacter pylori infection in duodenal ulcer patients

We defined optimal Helicobacter pylori (Hp) treatment as Hp eradication rate about 90%, well-tolerated with few side-effects. Two centers carried out randomized trials including 90 patients (74% men, 26% women, ages ranging from 18 to 65, mean age 42 +/- 8) with active duodenal ulcers (DU). Patients were treated with the combination of Omeprazole (O) 20 mg bd + Clarithromycin (C) 250 mg bd + Tinidazole (T) (500 mg bd) or with Lansoprazole (L) 15 mg bd + Amoxicillin (A) 750 mg bd + Metronidazole (M) 500 mg bd administered for one week. The DU healing rate was evaluated by endoscopy and the Hp status by rapid urease CLO-test and 14C-urea breath test (UBT). The healing rate of the DU in a group treated with the combination of O + C + T was 91% and in group treated with L + A + M was 93%. The eradication of Hp in group O + C + T and L + A + M averaged 91% and 87%, respectively. There was no statistically significant difference in the DU healing rate and the Hp eradication rate between these two groups. Both treatments were accompanied by a marked rise in the basal and postprandial plasma gastrin levels and the rise in the intragastric pH but these alterations returned to the pre-treatment values 4 weeks after the termination of the therapy. Both treatments were well tolerated and the only side effect was the taste disturbance observed in few patents treated with O + C + T. None of patients discontinued the treatment because of the adverse events. We conclude that one week treatment using O + C + T or L + A + M are highly and equally effective in the healing of DU and in the eradication of Hp.

Helicobacter pylori infection after gastrectomy and vagotomy in duodenal ulcer patients

The eradication of Helicobacter pylori (Hp) is known to reduce the recurrence rate of duodenal ulcer (DU) to similar extent as gastrectomy but it is not clear what is the prevalence of Hp in DU patients after surgical interventions such as gastrectomy or vagotomy. The purpose of this study was to evaluate the influence of gastrectomy or truncal vagotomy with pyloroplasty on the prevalence of Hp in 51 DU patients just before and 6-8 months after these procedures. Using C14-urea breath test (UTB), rapid CLO-test and histology of the biopsy samples of gastric mucosa obtained during gastroscopy, the Hp was detected in all DU subjects submitted to operation. Following distal gastric resection (antrectomy) with Billroth II anastomosis (N = 32) due to an ulcer resistance to conservative therapy, peptic ulceration was not observed during 6-8 months in any of the examined subjects and the Hp was only rarely observed (only in 3 out of 32 operated patients). Histologically, in antral biopsies taken prior to surgery, all DU patients presented chronic active gastritis. After the surgery, the absence of Hp was confirmed also by histology. Histological evaluation of gastrectomy stump biopsies revealed typical chronic gastritis with concomitant foveolar hyperplasia and focal gland dilation. Following selective vagotomy and pyloroplasty (N = 19), the scarring of duodenal bulb (without active ulcer) was seen in 4 out of 19 operated patients but the Hp was detected in all (100%) cases. Gastric biopsies prior and after vagotomy revealed chronic active gastritis associated with Hp infection. Basal plasma gastrin was reduced after gastrectomy by about 30% and basal and maximal pentagastrin-induced acid secretion was decreased by about 60% and 70%, respectively. Vagotomy did not reduce activity of the mucosal inflammation and the incidence of Hp. Basal plasma gastrin level was increased by about 60%, while basal and pentagastrin induced acid secretion was decreased by 25% and 40%, respectively. Because of the high ulcer recurrence rate after vagotomy as opposed to low recurrence after gastrectomy, it is reasonable to conclude that (1) the disappearance of Hp and reduction in plasma gastrin and gastric acid secretion were probably the major factors responsible for the high efficacy of gastrectomy in prevention of ulcer recurrence, (2) in non-complicated DU, gastric surgery should be avoided and replaced by conservative anti-Hp therapy involving both antisecretory or bismuth agents and antimicrobial drugs which should provide similar therapeutic effects as surgery and (3) vagotomy should be eliminated as the method of treatment of DU because of the high recurrence of peptic ulceration and the failure of this procedure to affect the Hp status.

Eradication of Helicobacter pylori and gastrin-somatostatin link in duodenal ulcer patients

Helicobacter pylori (Hp) infection may be associated with duodenal ulcer (DU) and accompanied by increased release of gastrin and deficiency of somatostatin (S-S) but the mechanisms of these changes in DU patients after eradication of Hp have been little studied. Cholecystokinin (CCK) has been implicated in the feedback control of gastric acid secretion in healthy subjects but its contribution to secretory disorders in DU patients has been little examined. This study, therefore, investigated whether CCK participates in the impairment of postprandial gastrin release and gastric acid secretion in active DU patients. Tests were undertaken in 10 DU patients without or with elimination of the action of endogenous CCK using loxiglumide (LOX), a selective CCK-A receptor antagonist, before and 4 wk. after eradication of Hp with triple therapy (omeprazole, amoxycillin and bismuth). In Hp positive DU patients, the postprandial acid secretion (measured by continuous intragastric pH monitoring) was accompanied by a pronounced increment in plasma gastrin with negligible increase of intraluminal release of S-S. The administration of LOX in these patients did not affect significantly the postprandial pH profile and the rise in plasma gastrin. After eradication of Hp the median postprandial intragastric pH increased to about 4.3 (compared to 3.5 before the Hp eradication); the postprandial gastrin concentration was reduced by about 40%, while luminal release of S-S was increased 2 folds. The administration of LOX resulted in significantly greater decrease in median pH (3.1) and higher rise in postprandial plasma gastrin in these patients. Also the postprandial plasma S-S showed a small, but significant decline (by about 25%) as compared to that in placebo treated patients. This study provides evidence that: (1) Hp infection in DU patients is accompanied by enhanced gastrin release and the reduction in luminal release of S-S; (2) The failure of LOX to affect gastric secretion and plasma gastrin DU Hp infected patients could be attributed, at least in part, to the failure of endogenous CCK to control gastric acid secretion via release of S-S; (3) Hp infected patients appear to exhibit a deficiency of S-S release that can be reversed by the eradication of Hp indicating that both peptides may contribute to the acceleration of the ulcer healing following Hp eradication in DU patients; (4) The test with LOX and gastric luminal S-S assay may be useful in identification of Hp positive DU patients with CCK-mediated impaired feedback control of gastric secretion and deficiency of S-S caused by Hp infection.

Role of endogenous nitric oxide in the control of exocrine and endocrine pancreatic secretion

L-Arginine (L-Arg), that is a substrate for nitric oxide (NO) synthase, stimulates the release of pancreatic islet hormones but the mechanism of this stimulation is unknown. The aim of this study was to determine the role of NO in the control of endocrine and exocrine pancreatic secretion in response to sham feeding (SF), ordinary meat feeding (F), duodenal perfusion with nutrients and i.v. infusion of gastrin releasing peptide (GRP) or urecholine in conscious dogs with chronic pancreatic fistulas. SF1 F, duodenal nutrient and GRP and urecholine resulted in the stimulation of pancreatic secretion reaching, respectively, 50%, 50%, 40%, 85% and 20% of maximal response to caerulein (200 pmol/kg-h i.v.). Infusion of L-Arg (50 mg/kg + 5 mg/kg-h i.v.) almost doubled the basal pancreatic protein secretion and significantly increased the secretory response to SF, F, and duodenal nutrient. After i.v. administration of L-NNA (2.5 mg/kg + 0.5 mg/kg-h), an inhibitor of NO synthase, the pancreatic secretory responses to SF, F, duodenal nutrient, GRP and urecholine were significantly inhibited by about 74%, 70%, 70%, 80% and 30%, respectively. When L-Arg was combined with L-NNA, the reduction in pancreatic secretion induced by L-NNA was significantly attenuated. SF resulted in a marked rise in plasma insulin and glucagon and this response was completely abolished by L-NNA infusion. Insulin and glucagon levels were 2-3 folds increased by F and L-NNA infusion inhibited these responses while the addition of L-Arg partly reversed this inhibition. Duodenal nutrient produced several fold increase in plasma insulin and glucagon levels that were significantly reduced by L-NNA and this reduction was partially reversed by L-Arg. GRP also caused moderate rise in plasma insulin and glucagon levels which were significantly reduced by L-NNA and this was partially restored by L-Arg. We conclude that SF, F, duodenal nutrient, GRP or urecholine stimulate both the exocrine and endocrine pancreatic secretion and that these effects are mediated, at least in part, through the NO pathway.

Solcoseryl in prevention of stress-induced gastric lesions and healing of chronic ulcers

Solcoseryl, a deproteinized extract of calf blood, protects the gastric mucosa against various topical irritants and enhances the healing of chronic gastric ulcerations but the mechanisms of these effects have been little studied. This study was designed to elucidate the active principle in Solcoseryl and to determine the role of prostaglandins (PG) and polyamines in the antiulcer properties of this agent. Using both, the radioimmunoassay and radioreceptor assay, EGF-like material was detected in Solcoseryl preparation. Solcoseryl given s.c. prevented the formation of stress-induced gastric lesions and this was accompanied by an increase in the generation of PGE2 in the gastric mucosa. Similar effects were obtained with EGF. Pretreatment with indomethacin, to suppress mucosal generation of prostaglandins (PG), greatly augmented stress-induced gastric ulcerations and antagonized the protection exerted by both Solcoseryl and EGF. Solcoseryl, like EGF, enhanced the healing of chronic gastro-duodenal ulcerations. This effect was abolished by the pretreatment with difluoromethylornithine, an inhibitor of ornithine decarboxylase, the key enzyme in the biosynthesis of polyamines. The healing effects of Solcoseryl and EGF was also reduced by prednisolone which decreased the angiogenesis in the granulation tissue in the ulcer area. These results indicate that Solcoseryl 1. contains EGF-like material, 2. displays the protective and ulcer healing effects similar to those of EGF and involving both PG and polyamines and 3. acts via similar mechanism as does EGF.

Comparison of organ uptake and disappearance half-time of human epidermal growth factor and insulin

Epidermal growth factor (EGF), which was originally identified in salivary glands and saliva, has been also found in the kidney and urine, suggesting that the kidney may be an alternate source of this peptide. Liver was considered as the major site of the degradation of EGF but the involvement of other organs has been little studied. Therefore, we carried out comparative studies on the organ uptake and the disappearance half-time of EGF and insulin (having similar molecular size) in the same model of anesthetized dog with arterial (from aorta) and venous (from mesenteric, portal, hepatic, renal, femoral and jugular veins) blood sampling from various organs. Basal plasma level of EGF (1.32 +/- 0.33 pmol/l) and insulin (62.1 +/- 13.8 pmol/l) in the aorta was not significantly different from that recorded at various sampling sites. During i.v. infusion of EGF at 41.6 and 166.6 pmol/kg/h, the respective arterial EGF concentrations averaged 103 +/- 21 and 240 +/- 49 pmol/kg/h and the percent reduction in plasma EGF after passage through the head, leg, intestines and liver was about 30-50% and that after passage through the kidney was about 95%. During insulin (6.9 pmol/kg/h) infusion, the arterial hormone level averaged 227 +/- 21 pmol/l and this level was significantly reduced (by 23-42%) after passage through the head, leg, intestine, liver and kidney but no significant difference was found between various venous sampling sites. EGF and insulin appearing in the urine during EGF or insulin infusion accounted for about 40 and 7% of the difference between the entering and leaving renal masses of the peptide. Mean disappearance half time on stopping of EGF and insulin infusion was, respectively, 2.32 +/- 0.58 and 6.88 +/- 1.25 min. We conclude that unlike insulin, which is removed to similar extent by various organs including the kidney and the liver, EGF is taken up mainly by kidney and EGF present in urine originates mainly from renal clearance of peptide.

Gastric acid, gastrin and pancreatic polypeptide responses to modified sham feeding in duodenal ulcer patients before and after highly selective or truncal vagotomy

Gastric acid secretion, as well as gastrin and pancreatic peptide release into the bloodstream before and after TV or HSV were observed in 28 patients following modified sham feeding (MSF) and pentagastrin tests. Prior to surgery the majority of patients showed stimulation of gastric acid secretion and hormone release into the bloodstream as the result of the employed tests. The MSF-induced acid output (SAO) and pentagastrin-induced acid output (PAOpg) values were mainly observed immediately following the stimulus. In the majority of patients MSF triggered an increase in blood gastrin and PP concentrations. Nevertheless, the peak concentration values for the two hormones occurred at different time intervals following the stimulus. For gastrin the peak values appeared later than SAO, whereas for PP they occurred either in the course of or immediately after MSF. Irrespectively of, the type of surgical procedure used and the completeness of vagotomy, the values of BAO, PAO, SAO and PAOpg were significantly lower following the procedure. Blood hormone concentration, however, showed greater variations. The test stimulated gastrin release showed the peak values were greater after, than prior to, the surgery, whereas PP release was markedly inhibited. No correlation was found between gastric acid secretion, blood serum gastrin and PP levels.

Effects of an antral mucosectomy, L-364,718 and atropine on cephalic phase of gastric and pancreatic secretion in dogs

The purpose of this study was to determine the role of gastrin and cholecystokinin in the cephalic phase of gastrin release and gastric and pancreatic secretion in conscious dogs. Sham feeding in intact dogs increased gastric acid output to about 65% of histamine maximum and pancreatic protein to 23% of caerulein maximum. Significant increases in plasma gastrin and pancreatic polypeptide but not cholecystokinin occurred. Similar effects were obtained using insulin hypoglycemia or 2-deoxy-D-glucose glucocytopemia. Atropine eliminated gastric acid response to sham feeding, insulin, or 2-deoxy-D-glucose, significantly reduced the pancreatic protein response by about 60%, and abolished plasma pancreatic polypeptide but not plasma gastrin. Blocking of cholecystokinin receptors by L-364,715 did not affect gastric or pancreatic secretory responses to sham feeding, insulin, or 2-deoxy-D-glucose and failed to influence the accompanying increments in plasma gastrin and pancreatic polypeptide. In antral-mucosectomized dogs, sham feeding-induced acid output reached only 17% of histamine maximum but the increase in pancreatic protein output was similar to that in intact dogs. In these animals, background stimulation with G17I (62 pmol/kg per h) potentiated the gastric acid response to sham feeding but had little effect on pancreatic protein output. This study provides evidence that unlike gastric acid, the pancreatic protein response to physiological or pharmacological cephalic stimulation does not depend on vagally released gastrin but probably on direct vagal stimulation of the pancreas.

CCK receptors in release of pancreatic polypeptide (PP) in dogs

Pancreatic polypeptide (PP) is released after ingestion of protein-fat meals and following administration of some gut hormones (CCK and bombesin), but the hormonal contribution to the physiological release of PP has not been elucidated. We used specific and potent CCK-receptor antagonist, L-364,718, administered intravenously in a dose of 0.5 mumol/kg or intraduodenally in a dose of 2 mumol/kg to assess the role of CCK in the release of PP. Exogenous CCK-8 infused intravenously in gradually increasing doses (12.5-400 pmol/kg/hr) caused a dose-dependent increase in plasma PP from basal 28 +/- 4 pM to 136 +/- 18 pM, and this PP increase was completely suppressed by both intravenous and intraduodenal administration of L-364,718. Meat feeding caused a dramatic increase in plasma PP from a basal level of 26 +/- 4 pM to a peak of about 190 +/- 32 pM, and the pretreatment with intravenous or intraduodenal L-364,718 reduced this PP increase by about 60%. Duodenal perfusion with oleate (0.12-4.0 mmol/hr) or L-Trp (0.12-4.0 mmol/hr) also increased plasma PP, reaching, respectively, 180 +/- 28 pM and 76 +/- 6 pM. Pretreatment with intravenous or intraduodenal L-364,718 completely abolished the plasma PP responses to oleate and L-Trp. Bombesin (100 pmol/kg/hr) raised plasma PP to the level similar to that achieved by meat feeding and L-364,718 given intravenously or intraduodenally blocked completely these plasma PP increments.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoneutralization of circulating pancreatic polypeptide and pancreatic secretion

To determine the role of endogenous pancreatic polypeptide (PP) as a physiological inhibitor of pancreatic secretion, normal rabbit serum (control) or rabbit PP-antiserum was administered intravenously to dogs with chronic esophageal, gastric, and pancreatic fistulas. In all dogs tested, sham-feeding and ordinary feed with a meat meal resulted in a marked rise in the plasma level of immunoreactive PP that coincided with an increase in the exocrine pancreatic secretion of HCO3- and protein. After intravenous administration of PP antiserum, endogenous plasma PP was almost completely bound by infused antibodies to PP, whereas no such binding was detected after infusion of normal rabbit serum. In contrast, plasma gastrin remained unchanged both under basal and stimulated conditions. Immunoneutralization of PP, released endogenously, failed significantly to affect gastric acid and pancreatic protein responses to sham-feeding and the pancreatic HCO3- and protein responses to feeding a meat meal in chronic pancreatic fistula dogs. However, the PP antiserum abolished, in part, the inhibitory effect of exogenous PP on pancreatic secretion stimulated by exogenous hormones. We conclude that endogenous PP is not a physiological inhibitor of exocrine pancreatic secretion, as has been suggested previously.

Gastric acid and pancreatic polypeptide responses to modified sham feeding. Effects of truncal and parietal cell vagotomy

The effects of truncal vagotomy and parietal cell vagotomy on gastric acid secretion and plasma gastrin and pancreatic polypeptide release were studied in 28 duodenal ulcer patients under basal conditions and after modified sham feeding and infusion of pentagastrin (2 micrograms/kg/h). Before vagotomy gastric acid output in response to modified sham feeding was significantly higher than basal acid secretion in all subjects tested and reached about 45% of the pentagastrin maximum. No difference in the increase in acid response, or in the pancreatic polypeptide response to modified sham feeding was found between patients with high and low basal secretion. Plasma gastrin concentration was unaltered by modified sham feeding before and after truncal vagotomy or parietal cell vagotomy, although after vagotomy it tended to reach higher values than before this procedure. After truncal vagotomy, basal pancreatic polypeptide concentration was decreased and modified sham feeding-induced pancreatic polypeptide increment was completely eliminated. Four weeks after parietal cell vagotomy, the modified sham feeding-induced increment in plasma pancreatic polypeptide was significantly decreased and observed only in seven of 12 patients. Four to five years after parietal cell vagotomy all subjects responded to modified sham feeding with pancreatic polypeptide increment similar to that before vagotomy and in three of 12 patients acid response to modified sham feeding was seen. This study indicates that truncal vagotomy eliminates gastric acid and plasma pancreatic polypeptide responses to vagal excitation while parietal cell vagotomy abolishes gastric acid response and reduces temporarily the pancreatic polypeptide response to modified sham feeding (possibly because of transient impairment of the vagal innervation of the pancreas). (2) A high ratio of basal to maximal acid output in non-operated duodenal ulcer patients is not associated with a low acid response to modified sham feeding, nor with a high pancreatic polypeptide concentration, and (3) Restitution of the pancreatic polypeptide response to modified sham feeding five years after parietal cell vagotomy does not indication ineffective denervation of the parietal cells.

Role of endogenous prostaglandins in duodenal alkaline response to luminal hydrochloric acid or arachidonic acid in conscious dogs

Duodenal secretion of HCO-3 and luminal release of PGE2 were measured in conscious dogs. The results show that the HCO-3 secretion is closely correlated with the luminal release of PGE2 and that both the HCO-3 and the PGE2 outputs increase dose-dependently after topical application of hydrochloric acid or arachidonic acid. Indomethacin reduced basal HCO-3 and PGE2 release and prevented their increase in response to hydrochloric acid or arachidonic acid. We conclude that mucosal PGE2 plays an important role in the alkaline secretion from the duodenum.

Studies on the localization of secretin release from canine intestine

In conscious dogs with chronic pancreatic fistulas, duodenal perfusion with HCl (16 mmol/h) stimulated pancreatic HCO-3 secretion to a similar degree as exogenous secretin (2 U/kg X h), while meat feeding (500 g) and duodenal perfusion with oleate (16 mmol/h) increased this secretion to about 58 and 43% of the highest response to secretin. Plasma secretin increments with duodenal HCl, feeding and duodenal oleate amounted to about 45, 13 and 8% of that achieved with secretin, producing the highest HCO-3 response. Perfusion of the in situ intestine with HCl at gradually increasing rates produced HCO-3 responses similar to those induced by exogenous secretin in graded doses, but the increments in plasma secretin with duodenal HCl were only about half those obtained with exogenous secretin, producing an equal rate of HCO-3 secretion. HCl perfusion of isolated Thiry loops made of the duodenojejunal portion also stimulated the HCO-3 secretion in a dose-dependent way, but raised plasma secretin only to about half that attained with secretin, producing a similar secretory rate. HCl in the proximal duodenal and distal jejunal loop slightly stimulated the HCO-3 secretion without affecting plasma secretin, and that in the ileal loop was without any effect on the pancreatic or plasma secretin. This study provides evidence that (a) endogenous secretin is released by feeding and duodenal perfusion with HCl and oleate, but only HCl appears to release sufficient amounts of secretin to drive the HCO-3 secretion, and (b) the release of secretin is confined mainly to the distal duodenum and proximal jejunum.

Effects of somatostatin-14 and somatostatin-28 on plasma hormonal and gastric secretory responses to cephalic and gastrointestinal stimulation in man

This study was designed to determine the influence of cephalic and gastrointestinal meal stimulation on plasma levels of somatostatin-like immunoreactivity (SLI) and to compare plasma hormonal and gastric secretory effects of somatostatin-14 (SS-14) and its putative prohormone, somatostatin-28 (SS-28), in humans. Cephalic stimulation induced by modified sham feeding did not affect plasma SLI, whereas a gastric liver extract meal caused a significant increase in SLI. Infusion of SS-28 dose-dependently suppressed gastric acid, serum gastrin, and plasma pancreatic polypeptide (PP) responses to cephalic and gastrointestinal stimulation. SS-28 was equipotent with SS-14 as gastric inhibitor when compared on the basis of molar doses infused but was 4-10 times less potent on the basis of plasma SLI concentrations obtained. A lower and more physiological dose of SS-14 (75 pmol/kg-h) reduced gastric acid and PP responses but failed to affect the serum gastrin response to a meal; whereas a larger, pharmacological dose (500 pmol/kg-h) also suppressed serum gastrin responses. We conclude that meal releases SLI into the circulation and that SS-28 mimics the gastric secretory and plasma hormonal effects of SS-14 but is several times less potent than SS-14 in terms of circulating hormone levels.

Effect of enkephalin and naloxone on gastric acid and serum gastrin and pancreatic polypeptide concentrations in humans

The effects of a synthetic enkephalin analogue with prolonged opioid activity, D-ala-2-enkephalin (ala-enk) and naloxone given alone or in combination, on vagally, pentagastrin- and histamine-induced gastric secretion and plasma hormonal responses to vagal stimulation have been studied in healthy subjects. D-ala-2-enkephalin reduced basal gastric acid and pepsin secretion, and caused a dose-dependent inhibition of gastric secretory responses to modified sham-feeding and pentagastrin but not to histamine. It increased serum gastrin concentration and suppressed plasma pancreatic polypeptide response to modified sham-feeding. Naloxone alone at lower dose levels did not affect gastric secretion and plasma hormonal concentrations but at higher doses it reduced both basal and modified sham-feeding-induced secretion. When combined with ala-enk it reversed in part gastric secretory and plasma hormonal changes induced by this peptide during modified sham-feeding and pentagastrin stimulation. These results indicate that (1) stable enkaphalin analogue inhibits basal and vagally or pentagastrin-induced gastric secretion, and affects plasma hormonal response to vagal stimulation, at least in part, via activation of opioid receptors and (2) endogenous opioid substances may be involved in the stimulation of gastric secretion in man.

Comparison of enkephalin and atropine in the inhibition of vagally stimulated gastric and pancreatic secretion and gastrin and pancreatic polypeptide release in dogs

Enkephalins have been detected in vagal nerves and myenteric plexus neurons but no study has been performed to determine their action on vagally stimulated gastric and pancreatic secretion. In this study we infused IV methionine-enkephalin (Met-enk) alone, naloxone (a pure opiate antagonist) alone, or their combination before, during and after vagal stimulation in 4 dogs with esophageal, gastric and pancreatic fistulas. For the comparison, atropine was given before, during and after vagal stimulation in the same animals. Vagal stimulation was obtained by 15 min sham-feeding, which produced an increase in gastric H+ output to a peak of about 75% of the maximal response to pentagastrin and pancreatic protein secretion amounting to about 71% of the maximal response to caerulein. It was accompanied by a significant rise in serum gastrin and pancreatic polypeptide (PP) levels. Met-enk inhibited significantly both gastric H+ and pancreatic protein secretion and reduced plasma PP but not gastrin levels. Similar effects were obtained after the administration of atropine. The effects of Met-enk were partly reversed by the addition of naloxone. We conclude that (1) enkephalin suppresses vagally stimulated gastric and pancreatic secretion and plasma PP release; (2) these secretory effects of enkephalin seem to be mediated by opiate receptors and could be explained by its inhibitory action on acetylcholine release ("anticholinergic" action) in the stomach and the pancreas.

Organ removal and disappearance half-time of synthetic human pancreatic polypeptide

Human pancreatic polypeptide (HPP) was infused into 6 anesthetized dogs at a constant dose of 1.0 micrograms/kg/h over 60 min. Blood samples for RIA of pancreatic polypeptide were taken repeatedly from a carotid artery, jugular vein, femoral vein, renal vein and mesenteric vein. The calculated tissue removal of HPP in a single passage through these four vascular beds ranged from 24 to 40% and did not differ significantly among them. Mean disappearance half-time on stopping the infusion was 4.5 +/- 0,8 min. The results indicate that HPP is removed at all of the capillary beds tested.