Risk of perforation during dilation for esophageal strictures after endoscopic resection in patients with early squamous cell carcinoma.

BACKGROUND AND STUDY AIMS: Growing evidence suggests that esophageal stricture frequently develops after endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD) in early esophageal cancer patients, with an incidence proportional to the greater extent of mucosal defects resulting from improved EMR/ESD techniques. There seems to be a potential risk of perforation during bougienage in such patients. PATIENTS AND METHODS: 648 stricture dilations for 78 lesions in 76 patients were consecutively included. The outcomes after combined use of Maloney and Savary wire-guided bougienage for esophageal strictures after EMR/ESD were analyzed in a single-institute retrospective case series study. The perforation rate was determined and risk factors for perforation were identified. RESULTS: Patients underwent a median of 5.0 dilation procedures performed over a median 3.0 months for post-EMR/ESD strictures. Initial dilation was done a median 14 days following endoscopic resection. Perforations developed in seven patients (7/648 dilation procedures, 1.1%), all in the lower esophagus, and bleeding occurred in one patient (0.1% dilations). Two independent risk factors for development of perforation during dilation therapy for post-EMR/ESD stricture were identified: multiple dilations (odds ratio [OR] 1.2; P=0.012), and lower site of stricture (OR 12.8; P=0.043). Dysphagia was ameliorated by the dilations, and no patient required surgery. CONCLUSIONS: A specific emerging risk of perforation in dilation therapy for post-EMR/ESD strictures was identified. Carefully planned treatment is necessary in patients with severe post-EMR/ESD strictures especially strictures requiring multiple dilations or located in the lower esophagus.

Proposal for a new clinical entity, IgG4-positive multiorgan lymphoproliferative syndrome: analysis of 64 cases of IgG4-related disorders.

BACKGROUND: Mikulicz's disease (MD) has been considered as one manifestation of Sjögren's syndrome (SS). Recently, it has also been considered as an IgG(4)-related disorder. OBJECTIVE: To determine the differences between IgG(4)-related disorders including MD and SS. METHODS: A study was undertaken to investigate patients with MD and IgG(4)-related disorders registered in Japan and to set up provisional criteria for the new clinical entity IgG(4)-positive multiorgan lymphoproliferative syndrome (IgG(4)+MOLPS). The preliminary diagnostic criteria include raised serum levels of IgG(4) (>135 mg/dl) and infiltration of IgG(4)(+) plasma cells in the tissue (IgG(4)+/IgG+ plasma cells >50%) with fibrosis or sclerosis. The clinical features, laboratory data and pathologies of 64 patients with IgG(4)+MOLPS and 31 patients with typical SS were compared. RESULTS: The incidence of xerostomia, xerophthalmia and arthralgia, rheumatoid factor and antinuclear, antiSS-A/Ro and antiSS-B/La antibodies was significantly lower in patients with IgG(4)+MOLPS than in those with typical SS. Allergic rhinitis and autoimmune pancreatitis were significantly more frequent and total IgG, IgG(2), IgG(4) and IgE levels were significantly increased in IgG(4)+MOLPS. Histological specimens from patients with IgG(4)+MOLPS revealed marked IgG(4)+ plasma cell infiltration. Many patients with IgG(4)+MOLPS had lymphocytic follicle formation, but lymphoepithelial lesions were rare. Few IgG(4)+ cells were seen in the tissue of patients with typical SS. Thirty-eight patients with IgG(4)+MOLPS treated with glucocorticoids showed marked clinical improvement. CONCLUSION: Despite similarities in the involved organs, there are considerable clinical and pathological differences between IgG(4)+MOLPS and SS. Based on the clinical features and good response to glucocorticoids, we propose a new clinical entity: IgG(4)+MOLPS.

Gain-of-function mutations of c-kit in human gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the human digestive tract, but their molecular etiology and cellular origin are unknown. Sequencing of c-kit complementary DNA, which encodes a proto-oncogenic receptor tyrosine kinase (KIT), from five GISTs revealed mutations in the region between the transmembrane and tyrosine kinase domains. All of the corresponding mutant KIT proteins were constitutively activated without the KIT ligand, stem cell factor (SCF). Stable transfection of the mutant c-kit complementary DNAs induced malignant transformation of Ba/F3 murine lymphoid cells, suggesting that the mutations contribute to tumor development. GISTs may originate from the interstitial cells of Cajal (ICCs) because the development of ICCs is dependent on the SCF-KIT interaction and because, like GISTs, these cells express both KIT and CD34.

Frequent epigenetic inactivation of SFRP genes and constitutive activation of Wnt signaling in gastric cancer.

Activation of Wnt signaling has been implicated in gastric tumorigenesis, although mutations in APC (adenomatous polyposis coli), CTNNB1 (beta-catenin) and AXIN are seen much less frequently in gastric cancer (GC) than in colorectal cancer. In the present study, we investigated the relationship between activation of Wnt signaling and changes in the expression of secreted frizzled-related protein (SFRP) family genes in GC. We frequently observed nuclear beta-catenin accumulation (13/15; 87%) and detected the active form of beta-catenin in most (12/16; 75%) GC cell lines. CpG methylation-dependent silencing of SFRP1, SFRP2 and SFRP5 was frequently seen among GC cell lines (SFRP1, 16/16, 100%; SFRP2, 16/16, 100%; SFRP5, 13/16, 81%) and primary GC specimens (SFRP1, 42/46, 91%; SFRP2, 44/46, 96%; SFRP5, 30/46, 65%), and treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine rapidly restored SFRP expression. Ectopic expression of SFRPs downregulated T-cell factor/lymphocyte enhancer factor transcriptional activity, suppressed cell growth and induced apoptosis in GC cells. Analysis of global expression revealed that overexpression of SFRP2 repressed Wnt target genes and induced changes in the expression of numerous genes related to proliferation, growth and apoptosis in GC cells. It thus appears that aberrant SFRP methylation is one of the major mechanisms by which Wnt signaling is activated in GC.

Transformation and morphological changes of murine L cells by transfection with a mutated form of beta-catenin.

To shed light on the oncogenic nature of mutant beta-catenin, we introduced a form of the cDNA that lacked an entire exon 3 into L cells derived from murine s.c. tissue. Aberrant beta-catenin protein accumulated in the cytoplasm and nuclei of these cells (designated L-MT), whereas in L cells transfected with wild-type beta-catenin (designated L-N), normal beta-catenin protein was expressed at a level similar to that of parental cells. L-MT cells also changed morphologically from a fibroblast-like appearance to a more cuboidal shape. Their rate of proliferation was the same as that of L cells and L-N cells, but the saturation density of L-MT cells appeared to increase in association with a multilayer growth pattern. Furthermore, L-MT cells required a lower concentration of serum in the growth medium than did parental cells. These alterations in cell growth and morphology suggested that mutated beta-catenin was stabilized in the transfected cells and induced the oncogenic phenotype.

Mutations of the bak gene in human gastric and colorectal cancers.

The Bcl-2 homologue Bak is a potent inducer of apoptosis. We performed PCR-based single-strand conformational polymorphism and sequencing analysis of the entire coding region of the bak gene (exons 2-6) in 24 primary gastric cancers (6 early-stage and 18 advanced-stage cancers) and 20 primary colorectal cancers (6 early-stage and 14 advanced-stage cancers). The data herein demonstrate, for the first time, the mutation of the bak gene in gastric and colorectal cancers. Missense bak gene mutations were observed in 3 of 24 (12.5%) gastric cancers and 2 of 20 (10.0%) colorectal cancers. Sequence alterations without amino acid alteration were observed 1 of 24 (4.2%) gastric cancers and 2 of 20 (10.0%) colorectal cancers. Mutations in the bak gene were observed only in advanced-stage gastrointestinal cancers but not in early-stage cancers. Our observations suggest that mutations in this gene predispose bearers to the development of gastrointestinal malignancies in at least a subset of the cases.

Modulation of apoptosis by endogenous Bcl-xL expression in MKN-45 human gastric cancer cells.

This study was designed to clarify the role of endogenous Bcl-xL expression in modulating apoptosis of malignant cells. Administration of bcl-x-antisense oligonucleotides decreased Bcl-xL protein levels in the MKN-45 human gastric cancer cell line. The decrease in Bcl-xL protein content resulted in increased cell death induced by serum deprivation or Fas-antibody administration. Flow cytometric analysis revealed that the increased apoptotic cell death was more prominent in bcl-x-antisense-treated cells as compared to control cells, bcl-x-sense-treated cells, or bcl-x-nonsense-treated cells. To inhibit the effect of intrinsic Bcl-xL protein, we overexpressed Bak, which binds Bcl-xL and inhibits the anti-apoptotic effect of Bcl-xL, by transfection into MKN-45 cells. Bak-overexpressing cells showed increased apoptotic cell death induced by Fas-antibody when compared to parent cells and MKN-neo-transfected cells. Bak-overexpressing cells also showed greater sensitization to 5-fluorouracil and cisplatin than parent cells and MKN-neo-transfected cells. In conclusion, we demonstrated that administration of bcl-x-antisense oligonucleotides or overexpression of Bak protein induces sensitization to apoptosis in MKN-45 gastric cancer cells, suggesting that endogenous Bcl-xL expression in cancer cells is an important modulator of apoptosis.

Purification and characterization of a phospholipase A2 from human ileal mucosa.

We purified a phospholipase A2 (PLA2) from human ileal mucosa to homogeneity. Its NH2-terminal amino acid sequence, amino acid composition, molecular weight, and elution behavior on reverse phase high-performance liquid chromatography were identical to those of human group II PLA2 purified from synovial fluid or spleen. The ileal PLA2 preferred anionic phosphatidylglycerol as substrate. On immunoblot analysis, human ileal mucosa gave more intense immunoreactivity with anti-human synovial fluid PLA2 antibody, at the same position as the purified enzyme, than the cecal mucosa. Northern blot analysis also showed that the level of group II PLA2 mRNA in the ileal mucosa was greater than that in the cecal mucosa. The enzyme was rather uniformly distributed over the colonic mucosa, from cecum to sigmoid colon. These results indicate that the ileal mucosa contains group II PLA2, and that its expression in the ileal mucosa was higher than that in the colonic mucosa.

Mucosal interleukin-1 beta production and acid secretion in enlarged fold gastritis.

BACKGROUND: We have previously shown that eradication of Helicobacter pylori increases acid secretion in H. pylori-associated enlarged fold gastritis. AIM: To investigate whether locally produced interleukin-1 beta is possibly involved in the inhibition of acid secretion in H. pylori gastritis. METHODS: IL-1 beta release from the gastric body mucosa was determined by short-term culture of biopsy specimens in 13 patients with enlarged fold gastritis (all H. pylori-positive), five H. pylori-positive and 10 H. pylori-negative patients without enlarged folds. The acid-inhibitory effect of locally produced IL-1 beta was examined by [14C]-aminopyrine uptake assay using isolated rabbit gastric glands. RESULTS: IL-1 beta release was significantly greater in patients with enlarged fold gastritis, significantly correlated with both basal and tetragastrin-stimulated acid outputs in the H. pylori-positive patients (r = -0.591 and r = -0.641, respectively; P < 0.01), and significantly decreased with concomitant increases in acid secretions after eradication of H. pylori. [14C]-aminopyrine uptake was inhibited by IL-1 beta in a dose-dependent manner. CONCLUSIONS: Increased production of IL-1 beta caused by H. pylori infection is possibly involved in the inhibition of acid secretion in enlarged fold gastritis.

Immunoreactive glucagons purified from dog pancreas, stomach and ileum.

Previous studies have shown that pig intestine contains a 69 amino acid glucagon (glicentin) as well as a 37 amino acid glucagon (oxyntomodulin). In pig pancreas the 29 amino acid glucagon predominates. Since glucagon is thought to be expressed from a single gene in mammals, these differences in molecular forms indicate differential posttranslational processing of the glucagon precursor by different tissues. In the current study glucagon immunoreactivity (IR) was separately purified from dog pancreas, stomach mucosa and ileum mucosa. Purification and sequence analysis of the different tissue glucagons show that dog pancreas and stomach mucosa contain glucagon-29 while ileum mucosa contains glucagon-37 and glucagon-69. The latter is the major form present with glucagon-37 accounting for only 10-20% of the total ileum glucagon content. The N-terminal 32 amino acid portion of dog glucagon-69 differs at 6 sites from pig glucagon-69: RSLQDTEEKSRSFSAPQTEPLNDLDQMNEDKR... The C-terminal glucagon-37 is identical to pig oxyntomodulin.

Somatostatin inhibits gastrin-induced histamine secretion and synthesis in the rat.

Somatostatin is a potent inhibitor of gastric acid secretion. However, the effect of somatostatin on gastric histamine secretion and synthesis has not been well understood, despite the fact that histamine plays a key role in the regulation of gastric acid secretion. This study was designed to determine the effect of somatostatin on gastric histamine mobilization and acid secretion in conscious rats. In conscious rats with a gastric fistula, a 4 h intravenous infusion of gastrin-17 I (1 nmol/kg/h) evoked a marked increase in fundic histidine decarboxylase activity (the sole histamine-forming enzyme) and reduced fundic histamine content with a concomitant increase in gastric acid secretion. Somatostatin-14 (10 nmol/kg/h) significantly inhibited gastrin-induced gastric acid secretion and fundic histidine decarboxylase activity and prevented a gastrin-induced decrease in fundic histamine content. In conscious rats with a vesical fistula, somatostatin-14 (10 nmol/kg/h) significantly inhibited the urinary histamine excretion induced by a gastrin-17 I (1 nmol/kg/h) infusion. These findings suggest that the inhibitory action of somatostatin on gastrin-induced acid secretion is mediated by the inhibition of histamine mobilization.

Effect of cholecystokinin receptor antagonists, MK-329 and L-365,260, on cholecystokinin-induced acid secretion and histidine decarboxylase activity in the rat.

To elucidate the regulatory mechanism of acid secretion by cholecystokinin (CCK) in vivo, we compared the effects of CCK and gastrin on acid secretion and histidine decarboxylase (HDC) activity. We also examined the effects of MK-329, a specific antagonist for pancreatic-type CCK receptor, and L-365,260, a specific antagonist for gastrin-type CCK receptor, on the action of CCK. Graded doses of CCK or gastrin were intravenously infused into conscious rats with gastric fistula. Gastrin-17 I infusion up to 10 nmol/kg/h resulted in dose-related increases in acid secretion. CCK-8 infusion also caused an increase in acid secretion. However, it reached a peak with 0.3 nmol/kg/h CCK-8 and attenuated with higher concentrations of CCK-8. This attenuating effect of a higher dose of CCK was reversed by MK-329, but not by L-365,260. Both CCK and gastrin were potent in increasing fundic HDC activity, and the effect of CCK on HDC activity was significantly inhibited by L-365,260, but not by MK-329. Taken together, the present study suggests that CCK and gastrin stimulate histamine formation via a gastrin-type CCK receptor, and the attenuating action of CCK with higher concentrations on acid secretion in vivo is mediated by a pancreatic-type CCK receptor.

Peptide YY-induced alteration of colonic electrolyte transport in the rat.

The effect of peptide YY (PYY) on active electrolyte transport in rat colon was studied under short-circuited conditions. PYY (10(-6) M) decreased the basal short-circuit current (Isc) in both the distal and proximal segments of the colon. The decrease in Isc induced by PYY in the distal colon was about 3 times larger than that in the proximal colon. The response to PYY was inhibited by diphenylamine 2-carboxylate, a specific blocker of the Cl-channel, but not by amiloride, a Na-channel blocker. Unidirectional flux measurements in the distal colon revealed that PYY increased the net Na and Cl absorption and decreased the serosal-to-mucosal Cl flux. PYY inhibited the neurally mediated secretory response to electrical field stimulation in a concentration-dependent manner. PYY was also shown to reduce the direct action of the cholinergic agonist bethanechol on the epithelium. These results suggest that PYY inhibits electrogenic Cl secretion and stimulates electroneutral NaCl absorption via both presynaptic and postsynaptic sites in the distal colon.