Showing papers by "S J Konturek published in 2001"

Expression of hepatocyte growth factor, transforming growth factor alpha, apoptosis related proteins Bax and Bcl‐2, and gastrin in human gastric cancer

Abstract: Background: Gastric cancer is one of the most frequent neoplasms and a leading cause of the death world-wide. In recent years, epidemiological and animal studies demonstrated a link between gastric cancer and chronic infection with H. pylori. The exact mechanism responsible for the development of gastric cancer in H. pylori-infected patients still remains unclear. There is evidence that the up-regulation of certain growth factors could play an important role in the promotion of the gastric carcinogenesis. Aims: The present study was designed to determine the gene expression of major known growth factors such as transforming growth factor alpha (TGFα), hepatocyte growth factor (HGF) and gastrin in the gastric cancer tissue, the surrounding mucosa and, for comparison, in the normal gastric mucosa. Furthermore, the luminal and plasma levels of gastrin in patients with gastric cancer were determined. In addition, the gene and protein expressions of apoptosis-related proteins such as Bax and Bcl-2 were investigated by reverse transcription-polymerase chain reaction and Western blot. Twenty-five gastric cancer patients and 40 age- and gender-matched control subjects hospitalized with non-ulcer dyspepsia were included into this study. Results: An overall H. pylori-seropositivity among gastric cancer patients was about 72% and was significantly higher than in the controls (56%). The prevalence of CagA-positive strains was also significantly higher among gastric cancer patients than in controls (56% vs. 32%). The gene expression of HGF and TGFα was detected more frequently in gastric cancer tissue samples than in normal gastric mucosa (52% vs. 12% for HGF and 48% vs. 24% for TGFα). The extent of protein expression in Western blotting analysis for HGF and TGFα correlated with the mRNA expression of these factors. Gene expression of gastrin was detected in the antrum of all tested patients and in the majority (84%) of gastric cancer patients. The median plasma and luminal concentrations of gastrin in gastric cancer patients were significantly higher than in controls. The gene expression of bcl-2 was detected in all (100%) and that of proapoptotic bax only in 56% of gastric cancer samples. In comparison to the surrounding non-tumorous tisssue, the gene expression of bax was significantly down-regulated and the gene expression of bcl-2 was up-regulated in gastric cancer tissue. At the protein level, Bax was not detectable and Bcl-2 was seen in 80% of gastric cancer samples. Conclusions: It is concluded that the patients infected with H. pylori, especially with CagA-positive strains, are at a higher risk of developing a gastric cancer. An increased production and release of gastrin, as well as an over-expression of growth factors such as HGF and TGFα, might contribute to the gastric carcinogenesis. In addition, a dysregulation of the Bax/Bcl-2 system with significant up-regulation of Bcl-2 is observed in gastric cancer.

Brain-gut axis in gastroprotection by leptin and cholecystokinin against ischemia-reperfusion induced gastric lesions.

Abstract: Leptin, a product of ob gene controlling food intake, has recently been detected in the stomach and shown to be released by CCK and implicated in gastroprotection against various noxious agents but it is unknown whether centrally applied leptin influences ischemia-reperfusion (I/R)-induced gastric erosions that progress into deeper gastric ulcerations. In this study we compared the effects of leptin and CCK-8 applied intracerebroventricularly (i.c.v.) or intraperitoneally (i.p.) on gastric mucosal lesions induced by I/R and topical application of 75% ethanol. Several major series of Wistar rats were used to examine the effects of leptin and CCK applied centrally on gastroprotection against I/R and ethanol in rats with A) vagotomy by cutting of vagal nerves, B) suppression of NO-synthase with L-NNA (20 mg/kg i.p.), C) inactivation of sensory nerves by capsaicin (125 mg/kg s.c.) and D) inhibition of CGRP receptors with CGR(8-37) (100 microg/kg i.p.) applied with or without the i.c.v. pretreatment with leptin or CCK-8. Rats were anesthetized 1 h after ethanol administration or at 3 h and 3 days upon the end of ischemia to measure the gastric blood flow (GBF) and then to determine the area of gastric lesions by planimetry. Blood was withdrawn for the measurement of plasma leptin and gastrin levels by radioimmunoassay (RIA). Leptin (0.1-20 microg/kg i.p.) dose-dependently attenuated gastric lesions induced by 75% ethanol and I/R; the dose reducing these lesions by 50% (ED50) was 8 microg/kg and 6 microg/kg, respectively and this protective effect was similar to that obtained with CCK-8 applied in a standard dose of 10 microg/kg i.p. This protective effect of leptin was accompanied by a significant increase in GBF and plasma gastrin levels whereas CCK-8 increased plasma leptin levels but failed to affect plasma gastrin levels. Leptin and CCK-8 applied i.c.v. in a dose of 625 ng/rat reduced significantly the area of I/R induced gastric lesions and raised the GBF and plasma leptin levels with the extent similar to those achieved with peripheral administration of leptin or CCK-8 (10 microg/kg i.p.). The protective and hyperemic effects of centrally administered leptin or CCK-8 (625 ng/rat i.c.v.) were completely abolished by vagotomy and significantly attenuated by sensory denervation with capsaicin or by CGRP antagonist, CGRP(8-37). The pretreatment with L-NNA to inhibit NO-synthase activity attenuated significantly the protective and hyperemic effects of CCK but not those of leptin while capsaicin denervation counteracted leptin-induced protection and rise in the GBF but attenuated significantly those of CCK. We conclude that: 1) central leptin exerts a potent gastroprotective activity against I/R-induced gastric erosions that progress into deeper gastric lesions and this protection depends upon vagal activity and sensory nerves and involves hyperemia probably mediated by NO and 2) leptin mimics the gastroprotective effect of CCK and may be implicated in the protective and hyperemic actions of this peptide against mucosal damage evoked by I/R.

Pancreatic damage and regeneration in the course of ischemia-reperfusion induced pancreatitis in rats.

Abstract: The objective of this study was to assess the biochemical and histological signs of pancreatic damage development and pancreatic recovery in the course of ischemia-reperfusion induced pancreatitis. Acute pancreatitis was induced in rats by limitation of pancreatic blood flow (PBF) in inferior splenic artery for 30 min using microvascular clips, followed by reperfusion. Rats were sacrificed at the time: 1 h, 12 h, 24 h, and 2, 3, 5, 7, 10, 14, 21 and 28 days after ischemia. PBF was measured using laser Doppler flowmeter. Plasma amylase, interleukin 1beta (IL-1beta) and interleukin 10 (IL-10) concentration, pancreatic DNA synthesis, as well as, morphological features of pancreatic damage were examined. Ischemia with reperfusion caused acute necrotizing pancreatitis followed by pancreatic regeneration. After removal of microvascular clips, PBF was reduced and the maximal fall of PBF was observed 24 h after ischemia, then PBF grew reaching the control value at 28th day. Plasma amylase activity was increased between 12th h and 3rd day with maximum at 24 h after ischemia. Also plasma IL-1beta and IL-10 were elevated with maximal value at the first and second day after ischemia, respectively. DNA synthesis was maximally reduced at the first day (by 70%) and from second day the reversion of this tendency was observed with full restoration of pancreatic DNA synthesis within four weeks. Morphological features of pancreatic tissue showed necrosis, strongly pronounced edema and leukocyte infiltration. Maximal intensity of morphological signs of pancreatic damage was observed between first and second day of reperfusion. During pancreatic regeneration between second and tenth day after ischemia the temporary appearance of chronic pancreatitis-like features such as fibrosis, acinar cell loss, formation of tubular complexes and dilatation of ducts was observed. The regeneration was completed within four weeks after pancreatitis development. We conclude that partial and temporary pancreatic ischemia followed by reperfusion causes acute necrotizing pancreatitis with subsequent regeneration within four weeks. Pancreatic repair after necrotizing pancreatitis is connected with the increase in plasma IL-10 concentration and transitory formation of tubular complexes.

Influence of Bacterial Lipopolysaccharide on Healing of Chronic Experimental Ulcer in Rat

Abstract: Background: Lipopolysaccharides (LPS) are major components of the outer membrane of Gramnegative bacteria, which play a central role as potent endotoxins in the pathogenesis of the Gram-negative septicaemia. Although it is well known that large amounts of endotoxin may produce haemorrhagic lesions in the stomach, the effect of LPS on ulcer healing has not been fully clarified. The aim of the present study was to examine the effect of parenteral injection of LPS at different doses on the course of ulcer healing in rats. Methods: Gastric ulcers were induced in Wistar rats by serosal application of an acetic acid area. After ulcer induction, vehicle (saline) or E. coli -LPS was injected at various doses (0.1, 1 and 5 mg/kg i.p.) for 7 days. The animals were sacrificed on day 8 after ulcer induction and the following parameters were analysed; ulcer area (planimetry), gastric blood flow (GBF) (H 2 gas clearance method), gastric secretion, plasma levels of proinflammatory cytokines such as IL-1 β and TNF α , mu...

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

Abstract: SUMMARY 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 (TGFα) 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 TGFα 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 α-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.

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

Abstract: 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, gastrointestinal and stress hormones in response to exercise in fasted or fed subjects and before or after blood donation.

Abstract: Leptin, an ob gene product of adipocytes, plays a key role in the control of food intake and energy expenditure but little is known about leptin response to strenuous exercise in fasted and fed subjects or before and after blood donation This study was designed to determine the immediate effects of strenuous exercise in healthy volunteers under fasting or fed conditions and before and one day after blood donation (450 ml) on plasma levels of leptin and gut hormones [gastrin, cholecystokinin (CCK), pancreatic polypeptide (PP) and insulin], as well as on "stress" hormones (cortisol, catecholamines and growth hormone Two groups (A and B) of healthy non-smoking male volunteers were studied All subjects performed incremental exercise tests until exhaustion (up to maximal oxygen uptake--VO2max), followed by 2 h of rest session Group A perfomed the tests on a treadmill, while group B on a cycloergometer In group A, one exercise was performed under fasting conditions and the second following ingestion of a standard liquid meal In group B, one exercise test was performed as a control test and the second 24 h after blood donation (450 ml) Blood samples were withdrawn 5 min before the start of the test, at the VO2max, and 2 h after finishing the exercise No significant change in plasma teptin were observed both immediately and 2 h after the exercise in fasted subjects, but after the meal the plasma leptin at VO2max and 2 h after the test was significantly higher, while after blood donation was significantly reduced The postprandial rise in plasma leptin was accompanied by a marked increment in gut hormones; gastrin, CCK and PP and stress hormones such as norepinephrine, cortisol and GH These hormonal changes could contribute to the postprandial rise in plasma leptin concentrations, while the fall of leptin after blood donation could be attributed to the inadequate response of stress hormones and autonomic nervous system to exhausting exercise We conclude that strenuous physical exercise; 1) fails to affect plasma leptin level but when performed after meal but not after blood withdrawal it results in an increase and fall in plasma leptin, and 2) the release of gut hormones (gastrin, CCK and PP) and stress hormones (norepinephrine, cortisol, GH) increase immediately after exercise independently of feeding or blood donation and 3) following blood donation the strenuous exercise resulted in a marked reduction in the plasma leptin, cortisol and GH concentrations, possibly due to the impairment in the autonomic nervous control of these hormones

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

Abstract: 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.

Effect of sensory nerves and CGRP on the development of caerulein-induced pancreatitis and pancreatic recovery.

Abstract: The function of primary sensory neurons is to receive and transmit information from external environment and these neurons are able to release neuromediators from the activated peripheral endings. The aim of this study was to determine the influence of sensory nerves and administration of their mediator--calcitonin gene related peptide (CGRP) on the course of acute pancreatitis (AP). Ablation of sensory nerves was performed by neurotoxic dose of capsaicin (100 mg/kg). Single or repeated episodes of AP were induced by caerulein infusion (10 microg/kg/h for 5 h). Five repeated AP were performed once a week. Capsaicin at the dose which stimulates sensory nerves (0.5 mg/kg/dose) or CGRP (10 microg/kg/dose) was administrated before and during or after single induction of AP, as well as, after each induction of repeated AP. Rats were killed at the time 0, 3 or 9 h after single induction of AP or two weeks after last induction of repeated AP. Ablation of sensory nerves aggravated pancreatic damage in caerulein-induced AP. Treatment with stimulatory doses of capsaicin or CGRP before and during single induction of AP attenuated the pancreatic damage in morphological examination. This effect was also manifested by partial reversion of AP evoked drop in DNA synthesis and pancreatic blood flow (PBF). Administration of CGRP after single AP induction aggravated histologically manifested pancreatic damage. The further decrease in PBF and DNA synthesis was also observed. Animals with five episodes of AP showed almost full pancreatic recovery two weeks after last induction of AP concerning all parameters tested. In stimulatory doses of capsaicin treated rats, we observed the decrease in pancreatic amylase and fecal chymotrypsin activity, as well as, the drop in DNA synthesis. Similar but less pronounced effects were observed after treatment with CGRP. We conclude that effect of sensory nerves and CGRP on AP is two-phase and time dependent. Stimulation of sensory nerves or the administration of CGRP during development of AP exhibits protective effects against pancreatic damage induced by caerulein overstimulation. After induction of AP, persistent activity of sensory nerves and presence of CGRP aggravate pancreatic damage and lead to functional insufficiency typical for chronic pancreatitis.

Effect of local injection with basic fibroblast growth factor (BFGF) and neutralizing antibody to BFGF on gastric ulcer healing, gastric secretion, angiogenesis and gastric blood flow.

Abstract: Exogenous administration of bFGF was shown to accelerate tissue repair predominantly due to an increase in the formation of new microvessels (angiogenesis) suggesting that bFGF plays an important role in healing of gastric ulcer This study was designed: 1) to examine the effect of local application of bFGF with or without neutralizing antibody (NA) to bFGF and 2) to determine the role of gastric secretion, gastric blood flow (GBF) at the ulcer margin and angiogenesis during gastric ulcer healing with or without local application of NA, bFGF or the combination of NA and bFGF Chronic gastric ulcers were induced in Wistar rats by subserosal application of acetic acid (ulcer area 28 mm2) and gastric secretion during ulcer healing was assessed using animals additionally equipped with chronic gastric fistulas The bFGF without or with NA to bFGF (10 ng/100 microl]), irrelevant antibodies (rabbit IgG; 10 microg/100 microl) or vehicle (saline) were locally injected into the subserosa immediately upon ulcer induction (day 0) and at day 2 Rats with acetic acid ulcers without subserosal injections served as controls At day 11, all animals were anaesthetized and GBF was determined at the ulcer base, ulcer margin as well as in intact mucosa using the H2-gas clearance technique and the area of gastric ulcers was measured by planimetry Gastric mucosa with ulcer was excised and the percentage of area covered with blood vessels, the number of fibroblasts and the percentage of connective tissue at the ulcer edge was assessed by histology The gastric ulcers were healed spontaneously in control vehicle-treated rats at day 11 and this was accompanied by the significant increase in the GBF and number of microvessels in the ulcer area The gastric secretion was suppressed immediately after ulcer induction and increased significantly at day 2 and day 11 but failed to return to that recorded in intact animals In contrast, local application of bFGF inhibited gastric acid and pepsin outputs at each study time intervals tested and this effect was reversed by addition of NA to bFGF Locally applied bFGF accelerated significantly ulcer healing and this was accompanied by the greater rise in the GBF of ulcer margin and more marked increase in number of microvessels as compared to those in vehicle-treated rats Subserosal application of NA to bFGF prolonged significantly the ulcer healing and this effect was accompanied by a significant fall in the GBF at the ulcer margin and a decrease in number of capillaries in ulcer bed without significant alteration in gastric acid and pepsin outputs The ulcer healing effect of bFGF and accompanying increase in the GBF at ulcer margin and in thenumber of microvessels as well as inhibition of gastric acid secretion evoked by bFGF were significantly attenuated by the addition of NA to bFGF The number of fibroblasts and the distribution of connective tissue did not differ between groups studied We conclude that; 1) depletion of endogenous bFGF at the ulcer area by specific NA to bFGF delays healing of gastric ulcers, reduces angiogenesis of ulcer bed and impairs the microcirculatory effect of this growth factor at the ulcer margin indicating that the availability of bFGF in the ulcer area plays a crucial role in the ulcer healing through induction of angiogenesis; 2) this prominent antiulcer effect of locally applied bFGF depends, at least in part, upon the inhibition of acid secretion by this peptide

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

Abstract: 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 vag...

Histamine in stress ulcer prophylaxis in rats.

Abstract: Background Gastrin and its analogues increase the gastric acid secretion, but also enhance mucosal defense mechanisms. On the other hand, increased formation of histamine leading to an increase in gastric acid secretion is accompanied with gastroprotection and acceleration of gastric ulcer healing. Aim Of this study was to examine the effect of histamine on stress induced gastric ulcers in rats. Methods Male Wistar rats were exposed to water immersion and restrain stress (WRS) for 3.5 h at 23 degrees C. Before WRS rats were pretreated with saline, histamine, ranitidine or omeprazole. Results WRS produces gastric lesions which were strongly reduced by ranitidine or omeprazole. Also treatment with histamine markedly reduced ulcer area evoked by WRS. Addition of histamine to ranitidine or omeprazole caused an additional reduction in ulcer area. Gastroprotective effect of histamine was accompanied with the increase in gastric blood flow (GBF). Administration of omeprazole or ranitidine alone was without significant effect on GBF. Histamine caused an slight decrease in gastric luminal pH, whereas ranitidine or omeprazole significantly increased gastric luminal pH. Plasma interleukin-1beta was significantly reduced after administration of omeprazole, ranitidine, or histamine, however, the effect of histamine was less pronounced. DNA synthesis was increased after administration of omeprazole, ranitidine or histamine when compared with WRS alone. Administration of histamine in combination with ranitidine or omeprazole caused an additional increase in DNA synthesis. Conclusions Histamine exhibits protective effect and increases gastroprotective effect of ranitidine and omeprazole against stress-induced gastric lesions. This effect of histamine seems to be independent on gastric acid secretion but related to the increase in gastric blood flow and the reduction in activation of cytokine cascade.

Eradication of Helicobacter pylori restores the inhibitory effect of cholecystokinin on gastric motility in duodenal ulcer patients.

Abstract: BACKGROUND Increased gastric emptying and defective action of endogenous cholecystokinin (CCK), that is known to inhibit this emptying, have been implicated in the pathogenesis of duodenal ulcer (DU). The aim of this double blind study was to assess whether CCK and somatostatin participate in the impairment of gastric motility in active DU patients before and after Helicobacter pylori eradication. METHODS Tests were undertaken in 10 DU patients without or with elimination of the action of endogenous CCK using loxiglumide, a selective CCK-A receptor antagonist, before and 4 weeks after eradication of H. pylori with 1 week triple therapy that resulted in healing of all DUs tested. The gastric emptying rate after feeding was determined using the 13C-acetate breath test. Before each test, samples of gastric juice were obtained by aspiration using a nasogastric tube for determination of somatostatin using specific radioimmunoassay. RESULTS Prior to H. pylori eradication gastric emptying half-time was 31 +/- 6 min in placebo-treated DU patients and this emptying rate was not significantly affected in tests after pretreatment with loxiglumide (10 mg/kg i.v.). Following eradication of H. pylori, in tests with placebo gastric emptying half-time was significantly longer (48 +/- 9 min) compared to that prior to H. pylori eradication. Pretreatment with loxiglumide in H. pylori eradicated DU patients significantly enhanced the gastric emptying rate with an emptying half-time of only 33 +/- 4 min. Eradication of H. pylori resulted in a significant increase in somatostatin concentration in gastric juice and loxiglumide significantly reduced this luminal somatostatin in H. pylori-eradicated subjects compared to values before anti-H. pylori therapy. CONCLUSIONS 1) H. pylori infection in DU patients is accompanied by enhanced gastric emptying and reduction in luminal release of somatostatin; 2) the failure of loxiglumide to affect gastric emptying in H. pylori-infected DU patients might be attributed, at least in part, to the failure of endogenous CCK to control gastric motility due to deficient release of somatostatin; and 3) H. pylori-infected patients appear to exhibit a deficient somatostatin release by endogenous CCK that can be reversed by the eradication of H. pylori indicating that both CCK and somatostatin may contribute to normalization of gastric emptying following H. pylori eradication in DU patients.

Heat shock protein 70 (HSP70) in gastric adaptation to aspirin in Helicobacter pylori infection.

Abstract: We have recently shown that adaptation of gastric mucosa to aspirin (ASA) is disturbed in Helicobacter pylori (H. pylori)-infected human stomach, but can be restored by eradication of the bacterium. The aim of this study was 1) to evaluate the influence of H. pylori on expression of heat shock protein 70 (HSP70) during ASA ingestion in these subjects and in mice model and 2) to evaluate, whether altered HSP70 expression might be associated with different adaptation to ASA in H. pylori-positive and eradicated subjects. The gastric mucosal HSP 70 gene expression was determined by quantitative RT-PCR and Western blot and immunohistochemistry during 14 days of ASA ingestion (1 g bid) in the same 8 subjects before and 3 months after successful eradication of H. pylori. In addition, HSP70 mRNA and protein expression were examined in 30 mice without and with H. pylori infection and eradication. During 14 days of ASA treatment, human H. pylori-infected mucosa revealed a decrease of HSP70 expression, while after eradication a higher expression and further increase of HSP70 expression during ASA ingestion were observed. Mice inoculated with H. pylori also exhibited decreased gastric mucosal HSP70 mRNA expression that was restored after eradication therapy. Decreased basal and ASA-induced expression of HSP70 may partly be responsible for impaired gastric adaptation to ASA in H. pylori-positive subjects. We conclude that 1. The HSP70 gene and protein expression is reduced during infection with H. pylori in men and mice and that gastric adaptation to ASA in H. pylori eradicated subjects is accompanied by increased HSP70 expression; 2. It is reasonable to assume that decreased HSP70 expression might contribute to disturbed gastric adaptation in H. pylori infection in humans and 3. The expression of HSP70 plays an important role in the mechanism of gastric adaptation to ASA and that H. pylori infection interferes with this adaptation due to decrease of HSP70 expression in gastric mucosal cells.

Sensory nerves and calcitonin gene related peptide in the effect of ischemic preconditioning on acute and chronic gastric lesions induced by ischemia-reperfusion.

Abstract: Ischemic preconditioning is considered as the most powerful gastroprotective intervention against mucosal lesions and ulcerations but the mechanism of this phenomenon has been little examined. In this study we tested the effects of inactivation of sensory nerves in new rat model combining acute gastric erosions with subsequent ulcers induced by ischemia-reperfusion (I/R). I/R lesions were produced in rats by clamping the celiac artery for 0.5 h followed b y3ho freperfusion in rats with intact or inactivated sensory nerves by pretreatment with capsaicin for two weeks before the I/R. The animals were killed at 0 and 3 h and 3 days after I/R and the area of gastric lesions was determined planimetrically, the gastric blood flow (GBF) by H2-gas clearance technique and the plasma levels of gastrin by RIA. Gastric mucosal content of calcitonin gene related peptide (CGRP) was assessed by RIA. Following I/R, gastric erosive lesions occurred after 3 h and these erosive lesions then progressed into gastric ulcers within 3 days in all rats. Sensory-inactivation with capsaicin caused several fold increase in the area of early (at 3 h) acute lesions and later (at 3 d) gastric ulcers induced by I/R. This enhancement of acute and then chronic gastric lesions was accompanied by a significant fall in GBF, an elevation of plasma gastrin and a decrease in mucosal expression of CGRP. Ischemic preconditioning markedly reduced acute lesions and chronic ulcerations induced by I/R and attenuated the changes in plasma gastrin and mucosal CGRP contents but these effects were significantly more pronounced in rats with intact sensory nerves but less in capsaicin-inactivated animals. We conclude that: 1) The I/R resulted in the formation of early acute gastric lesions followed 3 days later by chronic gastric ulcers and this gastric injury was accompanied by an impairment of gastric microcirculation, hypergastrinemia and suppression the gastric mucosal CGRP; 2) Gastric ischemic-preconditioning significantly attenuated both acute mucosal damage and chronic ulcers induced by I/R and this was accompanied by a rise in gastric blood flow; 3) The inactivation of sensory nerves with capsaicin enhanced the formation of I/R-induced acute and chronic gastric lesions and strongly attenuated the gastroprotection afforded by I/R possibly due to the decline in mucosal blood flow and the fall in expression of integrity peptides such as CGRP and 4) The excessive release of gastrin may limit the extent of mucosal lesions observed during progression of gastric erosions into ulcers induced by I/R.

Effect of central and peripheral actions of histamine and its metabolite n-alpha methyl histamine on gastric secretion and acute gastric lesions

Abstract: N alpha-methylhistamine (N alpha-MH) is one of unusual metabolite of histamine that was found in Helicobacter pylori-infected stomach and is believed to interact with specific histamine H1, H2 and H3-receptors to stimulate gastric acid secretion and gastrin release from isolated G-cells but the effects of N alpha-MH on gastric mucosal integrity have been little studied. This study was designed; 1) to compare the effect of intraperitoneal (i.p.), intracerebroventricular (i.c.v.) and gastric topical (intragastric i.g.) application of exogenous N alpha-MH with that of standard histamine on gastric secretion in rats equipped with gastric fistula (series A) and 2) to compare the effect of i.c.v. administration of histamine and N alpha-MH with that of peripheral (i.p. and i.g.) application of these amines on gastric lesions induced by 100% ethanol (series B) in rats with or without capsaicin-induced deactivation of sensory nerves. The area of gastric lesions was determined planimetrically, gastric blood flow (GBF) was assessed by H2-gas clearance method and venous blood was collected for determination of plasma gastrin levels by RIA. N alpha-MH and histamine (0.1-10 mg/kg i.p. or i.g.) dose-dependently increased gastric acid output (series A); whereas i.c.v. administration of histamine or N alpha-MH inhibited dose-dependently this secretion; the dose attenuating gastric acid output by 50% (ED50) being 4 and 6 microg/kg i.c.v. Both, N alpha-MH and histamine (2 mg/kg i.p. and i.g.) attenuated significantly the area of gastric lesions induced by 100% ethanol (series B) while producing significant rise in the GBF and plasma immunoreactive gastrin increments. Central application of N alpha-MH and histamine (0.01-5 microg/kg i.c.v.) inhibited ethanol-induced gastric damage whereas higher doses ranging from 10-100 microg/kg of histamine and N alpha-MH were significantly less effective. Capsaicin-induced deactivation of sensory nerves by itself augmented significantly ethanol damage and attenuated significantly the protective and hyperemic effects of histamine and its methylated analog applied i.p. but failed to affect significantly those caused by i.c.v. administration of these amines. We concluded that: 1) central histamine and N alpha-MH inhibits gastric acid secretion and exhibits gastroprotective activity against ethanol in similar manner to that afforded by parenteral and topical histamine and N-alphaMH, 2) central N-alphaMH- and histamine-induced protection involve the enhancement in gastric microcirculation unrelated to neuropeptides released from capsaicin-sensitive afferent nerves, and 3) the major difference between central and peripheral histamine and its methylated analog is the influence on gastric acid secretion which does not appear to play any major role in gastroprotective activity of these agents.

Central and peripheral neural aspects of gastroprotective and ulcer healing effects of lipopolysaccharides

Abstract: Lipopolysaccharides (LPS) are major components of the outer membrane of Gram-negative bacteria playing a central role as potent endotoxins in the pathogenesis of endotoxic shock. Although large amounts of endotoxin may produce hemorrhagic lesions in the stomach, the possible gastroprotective effect of central or peripheral LPS against the acute gastric lesions has not been extensively studied. The aim of the present study was to compare the effect of intracerebroventricular (i.c.v.) and parenteral (i.p.) injection of LPS against gastric lesions induced by 100% ethanol. Male Wistar rats were treated either with a) vehicle (control); b) E-coli-LPS in various concentrations (1—10 g/kg i.c.v or 0.1—40 mg/kg i.p.) followed 30 min later by 100% ethanol. The effects of pretreatment with nonselective inhibitor of nitric oxide synthase (L-NAME, 20 mg/kg i.g.) or selective inhibitor of inducible nitric oxide synthase, L-NIL (30 mg/kg i.g) on the gastroprotection induced by LPS was investigated. One hour after ethanol application, the gastric blood flow (GBF) and the area of gastric lesions were determined. In addition, the mucosal expression of iNOS, cNOS and leptin was assessed using RT-PCR. LPS applied i.c.v. or i.p. dose dependently reduced gastric lesions induced by ethanol and this effect was similar to that observed after the administration of NO donor (SNAP). LPS-induced protection was significantly abolished by L-NAME and significantly attenuated by the selective inhibitor of iNOS (L-NIL). The expression of cNOS was detected in vehicle treated gastric mucosa and did not change after LPS administration. iNOS was not detectable in intact mucosa but its expression dose-dependently increased after the LPS administration. The i.c.v. administration of LPS did not upregulate further the iNOS expression, and dose-dependently inhibited the leptin mRNA expression in gastric mucosa. We conclude that LPS applied centrally or peripherally protects gastric mucosa against ethanol-induced damage through an increase in gastric microcirculation mediated by NO due to overexpression of iNOS. Transcriptional downregulation of leptin in gastric mucosa is probably due to the increased leptin release induced by the intracerebroventricular application of lipopolysaccharide.

Incidence of Chlamydia pneumoniae infection in patients with coronary artery disease subjected to angioplasty or bypass surgery.

Abstract: BACKGROUND Seroepidemiological, pathological and animal studies suggest that chronic infection with Chlamydia pneumoniae (Cp) may directly impact the development or progression of atherosclerosis and coronary heart disease. The aim of the present study was to determine the seroprevalence of Cp infection and markers of systemic inflammation in patients undergoing routine coronary artery examination and prior to heart revascularization. MATERIAL AND METHODS The research involved 76 patients with severe CAD and 81 control patients with normal coronary circulation confirmed by coronary angiography. The presence of serum IgG and IgA antibodies to Cp and plasma interleukin-8 (IL-8) levels was measured by EIA test. Furthermore, the levels of plasma C-reactive protein, fibrinogen, total cholesterol, and triglycerides were measured in all patients. RESULTS Seropositivity to Cp was found in 60.5% for IgG and in 61.8% of cases for IgA with CAD patients, as compared to 26.0% and 29.5% in the controls (p<0.001), respectively. The levels of Interleukin-8, plasma fibrinogen, total cholesterol and triglycerides were significantly higher (p<0.001) in the CAD group, while C-reactive protein tended to have a higher value in patients with atherosclerosis than in the control group, although the difference was not significant. CONCLUSIONS Cp infection significantly increases the risk of CAD, usually requiring coronary bypass surgery or percutaneous coronary intervention as effective measures. It may also modify the levels of serum lipids, CRP and fibrinogen, increasing the risk of atherosclerosis. The strong correlation between the elevated IgG and IgA titers of Cp in patients treated with angioplasty or surgery may impact their follow-up; this issue requires further investigation.

Effects of biofeedback training on esophageal peristaltis in amyotrophic lateral sclerosis [ALS] patients with dysphagia

Abstract: Esophageal manometry (EM) could serve as an objective method for the detection of esophageal peristalsis in patients with amyotrophic lateral sclerosis (ALS). In this group of patients, biofeedback training (BT) using the EM procedure is a promising method for the rehabilitation of swallowing function. A total of 20 ALS patients with clinical evidence of dysphagia and who met WFN criteria were recruited for this study. The standard transnasal EM with solid-state transducers was performed, and swallows with water and saliva were initiated in all subjects and repeated at 30-s intervals. The median upper esophageal contractile amplitude, duration, and velocity results during the wet and dry swallows were evaluated and compared in both the ALS and the control groups. In ALS patients, in contrast to the control, significant abnormalities in all EM parameters were recorded, which implies a specific pattern of esophageal peristalsis. Twelve months after BT, the body mass index (BMI) of ALS patients who underwent BT (ALSBT) was compared to the BMI of those who did not (ALS1)—compared to the ALS1 group, ALSBT patients showed a slightly smaller drop in BMI value. We presume that BT using EM can be a promising tool for the improvement of the swallowing mechanism in ALS patients.