Comparison of endoscopic band ligation and endoclip closure of colonic perforation: technical feasibility and efficacy in an ex vivo pig model.

BACKGROUND AND AIM: Recent reports have indicated several instances of successful treatment of bowel perforation by using endoscopic band ligation (EBL) when treatment with endoclipping is unsuccessful, but this salvage method has not been investigated in any prospective model. Herein we aimed to compare the technical feasibility and efficacy of EBL and endoclip use in intraluminal closure of colon perforation, in an ex vivo model. METHODS: Standardized colonic perforations were created using fresh porcine colon and subsequently closed by full-thickness interrupted sutures, endoclip (QuickClip2(TM)), or EBL. Each closure site was tested with compressed air by using a digital pressure monitor for evaluating leak pressure. RESULTS: No significant differences were noted between the endoclip and EBL in leak pressures. Mean (± SD) pressures for air leakage from the perforations closed using the different devices were as follows: normal colon samples, 52.0 ± 13.2 mmHg; perforations closed with hand-sewn sutures, 32.3 ± 8.3 mmHg; perforations closed with endoclipping, 53.5 ± 22.7 mmHg; and perforations closed with EBL, 50.4 ± 12.5 mmHg. Time taken for closure by EBL was significantly less than that for closure by endoclipping (3.2 ± 1.7 min vs 6.8 ± 1.3 min, P < 0.01). Further, the number of devices used to achieve complete closure in the EBL group was lower than that with endoclipping (1.6 ± 0.5 vs 3.7 ± 0.8, P < 0.01). CONCLUSION: Endoluminal closure of a 1.5-cm colon perforation with EBL decreased procedure time and was not inferior in leak pressure compared with endoclipping in this ex vivo porcine model.

H2 Receptor-Mediated Relaxation of Circular Smooth Muscle in Human Gastric Corpus: the Role of Nitric Oxide (NO).

This study was designed to examine the effects of histamine on gastric motility and its specific receptor in the circular smooth muscle of the human gastric corpus. Histamine mainly produced tonic relaxation in a concentration-dependent and reversible manner, although histamine enhanced contractility in a minor portion of tissues tested. Histamine-induced tonic relaxation was nerve-insensitive because pretreatment with nerve blockers cocktail (NBC) did not inhibit relaxation. Additionally, K(+) channel blockers, such as tetraethylammonium (TEA), apamin (APA), and glibenclamide (Glib), had no effect. However, N(G)-nitro-L-arginine methyl ester (L-NAME) and 1H-(1,2,4)oxadiazolo (4,3-A) quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase (sGC), did inhibit histamine-induced tonic relaxation. In particular, histamine-induced tonic relaxation was converted to tonic contraction by pretreatment with L-NAME. Ranitidine, the H2 receptor blocker, inhibited histamine-induced tonic relaxation. These findings suggest that histamine produced relaxation in circular smooth muscle of human gastric smooth muscle through H2 receptor and NO/sGC pathways.

A case of idiopathic colonic varices: a rare cause of hematochezia misconceived as tumor.

Colonic varices are a very rare cause of lower gastrointestinal bleeding. Fewer than 100 cases of colonic varices, and 30 cases of idiopathic colonic varices (ICV) have been reported in the English literature. Among these 30 cases of ICV, 19 cases were diagnosed by angiography, and 7 operated cases were diagnosed later as ileocecal vein deficit, hemangioma, and idiopathic in 1, 1, 5 cases, respectively. We report the case of a 24-year-old man who suffered from multiple episodes of hematochezia of varying degree at the age of 11 years. He had severe anemia with hemoglobin of 21 g/L. On colonoscopy, tortuously dilated submucosal vein and friable ulceration covered with dark necrotic tissues especially at the rectosigmoid region were seen from the rectum up to the distal descending colon. It initially appeared to be carcinoma with varices. Mesenteric angiographic study suggested a colonic hemangioma. Low anterior resection was done due to medically intractable and recurrent hematochezia. Other bowel and mesenteric vascular structures appeared normal. Microscopic examination revealed normal colonic mucosa with dilated veins throughout the submucosa and serosa without representing new vessel growth. Taken all of these findings together, the patient was diagnosed as ICV. His postoperative course was uneventful.

Expression of human Calbindin-D(9k) correlated with age, vitamin D receptor and blood calcium level in the gastrointestinal tissues.

OBJECTIVE: Calbindin-D(9k) (CaBP-9k) has been thought to be one of the important factors of calcium absorption and metabolism in the intestine. The understanding of CaBP-9k role in the gastrointestinal tissues is important in human in relation with aging and gender, and whether there is any relationship with mineral homeostasis and risk for the development of age-related calcium disorders such as osteoporosis. DESIGN AND METHODS: The expression of CaBP-9k and vitamin D receptor (VDR) was analyzed in the human gastrointestinal tissues with different ages and gender. In addition, the correlation among CaBP-9k expression, age and calcium concentration in blood was elucidated in these tissues. RESULTS: A significant increase in the expression of CaBP-9k mRNA was observed in the bulb and 2(nd) portion of duodenum over age in both men and women. However, no significant age-associated change in VDR mRNA level was detected in the duodenum. The concentration of blood calcium level decreased with age in both men and women. CONCLUSION: The duodenal CaBP-9k may be not involved in calcium absorption in these tissues. The functional significance of the increase in the intestinal CaBP-9k expression with age is not currently clear and requires further investigation.

High k(+)-induced relaxation by nitric oxide in human gastric fundus.

This study was designed to elucidate high K(+)-induced relaxation in the human gastric fundus. Circular smooth muscle from the human gastric fundus greater curvature showed stretch-dependent high K(+) (50 mM)-induced contractions. However, longitudinal smooth muscle produced stretch-dependent high K(+)-induced relaxation. We investigated several relaxation mechanisms to understand the reason for the discrepancy. Protein kinase inhibitors such as KT 5823 (1 µM) and KT 5720 (1 µM) which block protein kinases (PKG and PKA) had no effect on high K(+)-induced relaxation. K(+) channel blockers except 4-aminopyridine (4-AP), a voltage-dependent K(+) channel (K(V)) blocker, did not affect high K(+)-induced relaxation. However, N(G)-nitro-L-arginine and 1H-(1,2,4)oxadiazolo (4,3-A)quinoxalin-1-one, an inhibitors of soluble guanylate cyclase (sGC) and 4-AP inhibited relaxation and reversed relaxation to contraction. High K(+)-induced relaxation of the human gastric fundus was observed only in the longitudinal muscles from the greater curvature. These data suggest that the longitudinal muscle of the human gastric fundus greater curvature produced high K(+)-induced relaxation that was activated by the nitric oxide/sGC pathway through a K(V) channel-dependent mechanism.

Mechanism of action of cholecystokinin on colonic motility in isolated, vascularly perfused rat colon.

BACKGROUND/AIMS: It is generally believed that cholecystokinin (CCK) stimulates colonic motility, although there are controversial reports. It has also been suggested that postprandial peptide YY (PYY) release is CCK-dependent. Using a totally isolated, vascularly perfused rat colon, we investigated: (1) the roles of CCK and PYY on colonic motility, (2) to determine if CCK modulates PYY release from the colon to influence the motility and (3) to clarify whether the action of CCK and PYY on colonic motility is mediated via the influence of cholinergic input. METHODS: An isolated whole rat colon was used. Luminal pressure was monitored via microtip catheter pressure transducers from proximal and distal colon. After a control period, CCK-8 or PYY was administerd intraarterially with or without an anti-PYY serum, loxiglumide or atropine at 12, 60 and 240 pM. Each dose was given for a period of 15-minute and the contractile response was expressed as % changes over basal. PYY concentration in the portal effluent was determined by radioimmunoassay. RESULTS: Exogenous CCK-8 increased colonic motility which paralleled the increase in PYY release in the portal effluent. Exogenous PYY also significantly increased colonic motility although it was less potent than CCK. The stimulating effect of CCK-8 was significantly inhibited by an anti-PYY serum, and was completely abolished by loxiglumide, and almost completely abolished by atropine. CONCLUSIONS: CCK increases colonic motility via CCK(1) receptor and it is mediated partly by PYY. Cholinergic input is required for the increased motility by either PYY or CCK.

Nitric Oxide-mediated Relaxation by High K in Human Gastric Longitudinal Smooth Muscle.

This study was designed to elucidate high-K(+)induced response of circular and longitudinal smooth muscle from human gastric corpus using isometric contraction. Contraction from circular and longitudinal muscle stripes of gastric corpus greater curvature and lesser curvature were compared. Circular smooth muscle from corpus greater curvature showed high K(+) (50 mM)-induced tonic contraction. On the contrary, however, longitudinal smooth muscle strips showed high K(+) (50 mM)-induced sustained relaxation. To find out the reason for the discrepancy we tested several relaxation mechanisms. Protein kinase blockers like KT5720, PKA inhibitor, and KT5823, PKG inhibitor, did not affect high K(+)-induced relaxation. K(+) channel blockers like tetraethylammonium (TEA), apamin (APA), glibenclamide (Glib) and barium (Ba(2+)) also had no effect. However, N(G)-nitro-L-arginine (L-NNA) and 1H-(1,2,4) oxadiazolo (4,3-A) quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase (sGC) and 4-AP (4-aminopyridine), voltage-dependent K(+) channel (K(V)) blocker, inhibited high K(+)-induced relaxation, hence reversing to tonic contraction. High K(+)-induced relaxation was observed in gastric corpus of human stomach, but only in the longitudinal muscles from greater curvature not lesser curvature. L-NNA, ODQ and K(V) channel blocker sensitive high K(+)-induced relaxation in longitudinal muscle of higher portion of corpus was also observed. These results suggest that longitudinal smooth muscle from greater curvature of gastric corpus produced high K(+)-induced relaxation which was activated by NO/sGC pathway and by K(V) channel dependent mechanism.

Regional Distribution of Interstitial Cells of Cajal (ICC) in Human Stomach.

We elucidated the distribution of interstitial cells of Cajal (ICC) in human stomach, using cryosection and c-Kit immunohistochemistry to identify c-Kit positive ICC. Before c-Kit staining, we routinely used hematoxylin and eosin (HE) staining to identify every structure of human stomach, from mucosa to longitudinal muscle. HE staining revealed that the fundus greater curvature (GC) had prominent oblique muscle layer, and c-Kit immunostaining c-Kit positive ICC cells were found to have typical morphology of dense fusiform cell body with multiple processes protruding from the central cell body. In particular, we could observe dense processes and ramifications of ICC in myenteric area and longitudinal muscle layer of corpus GC. Interestingly, c-Kit positive ICC-like cells which had morphology very similar to ICC were found in gastric mucosa. We could not find any significant difference in the distribution of ICC between fundus and corpus, except for submucosa where the density of ICC was much higher in gastric fundus than corpus. Furthermore, there was no significant difference in the density of ICC between each area of fundus and corpus, except for muscularis mucosa. Finally, we also found similar distribution of ICC in normal and cancerous tissue obtained from a patient who underwent pancreotomy and gastrectomy. In conclusion, ICC was found ubiquitously in human stomach and the density of ICC was significantly lower in the muscularis mucosa of both fundus/corpus and higher in the submucosa of gastric fundus than corpus.

Relaxation patterns of human gastric corporal smooth muscle by cyclic nucleotides producing agents.

To elucidate the mechanism of cyclic nucleotides, such as adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5' -cyclic monophosphate (cGMP), in the regulation of human gastric motility, we examined the effects of forskolin (FSK), isoproterenol (ISO) and sodium nitroprusside (SNP) on the spontaneous, high K(+) and acetylcholine (ACh)-induced contractions of corporal circular smooth muscle in human stomach. Gastric circular smooth muscle showed regular spontaneous contraction, and FSK, ISO and SNP inhibited its phasic contraction and basal tone in a concentration-dependent manner. High K(+) (50 mM) produced sustained tonic contraction, and ACh (10 microM) produced initial transient contraction followed by later sustained tonic contraction with superimposed phasic contractions. FSK, ISO and SNP inhibited high K(+)-induced tonic contraction and also ACh-induced phasic and tonic contraction in a reversible manner. Nifedipine (1 microM), inhibitor of voltage-dependent L-type calcium current (VDCC(L)), almost abolished ACh-induced phasic contractions. These findings suggest that FSK, ISO and SNP, which are known cyclic nucleotide stimulators, inhibit smooth muscle contraction in human stomach partly via inhibition of VDCC(L).

Voltage-dependent Ca Current Identified in Freshly Isolated Interstitial Cells of Cajal (ICC) of Guinea-pig Stomach.

The properties of voltage dependent Ca(2+) current (VDCC) were investigated in interstitial cells of Cajal (ICC) distributed in the myenteric layer (ICC-MY) of guinea-pig antrum. In tissue, ICC-MY showed c-Kit positive reactions and produced driving potentials with the amplitude and frequency of about 62 mV and 2 times min(-1), respectively, in the presence of 1 microM nifedipine. Single ICC-MY isolated by enzyme treatment also showed c-Kit immunohistochemical reactivity. These cells were also identified by generation of spontaneous inward current under K(+) -rich pipette solution. The voltage clamp experiments revealed the amplitude of - 329 pA inward current at irregular frequency. With Cs(+)-rich pipette solution at V(h)=-80 mV, ICC-MY produced voltage-dependent inward currents (VDIC), and nifedipine (1 microM) blocked VDIC. Therefore, we successfully isolated c-Kit positive single ICC from guinea-pig stomach, and found that ICC-MY potently produced dihydropiridine sensitive L-type voltage-dependent Ca(2+) currents (VDCC(L)).

Effects of polyamines on contractility of guinea-pig gastric smooth muscle.

This study was designed to investigate the effects of polyamines on mechanical contraction and voltage-dependent calcium current (VDCC) of guinea-pig gastric smooth muscle. Mechanical contraction and calcium channel current I(Ba) were recorded by isometric tension recording and whole-cell patch clamp technique. Spermine, spermidine and putrescine inhibited spontaneous contraction of the gastric smooth muscle in a concentration-dependent manner. Spermine (2 mM) reduced high K+ (50 mM)-induced contraction to 16+/-6.4% of the control (n=9), and significantly inhibited I(Ba) in a reversible manner (p<0.05; IC50=0.8 mM). Pre- and post-treatment of tissue with spermine (2-5 mM, n=10) also inhibited acetylcholine (10 microM)-induced phasic contraction to 5+/-6.4% of the control. Inhibitory effect of spermine on I(Ba) was observed at a wide range of test potentials of current/voltage (I/V) relationship (p<0.05), and steady-state activation of I(Ba) was shifted to the right by spermine (p<0.05). Spermidine and putrescine (1 mM each) also inhibited I(Ba) to 51+/-5.7% and 81+/-5.3% of the control, respectively. And putrescine (1 mM) inhibited I(Ba) at whole tested potentials (p<0.05) without significant change of kinetics (p<0.05). Finally, 5 mM putrescine also inhibited high K+-induced contraction to 53+/-7.1% of the control (n=4). These findings suggest that polyamines inhibit contractions of guinea-pig gastric smooth muscle via inhibition of VDCC.

Increased expression of sonic hedgehog and altered methylation of its promoter region in gastric cancer and its related lesions.

The hedgehog (Hh) signaling pathway plays an important role in foregut development, and its activity is increased in various tumors, including those of the digestive tract. Our objective in the present study was to determine the pattern and extent of Sonic hedgehog (Shh) expression in gastric cancer and related lesions as well as the methylation status of its promoter region, in an attempt to clarify the regulatory mechanism of Shh expression. A total of 237 gastric cancers and related lesions (89 carcinomas, 22 high-grade dysplasia, 21 low-grade dysplasia, 47 intestinal metaplasia, 38 chronic gastritis, and 20 normal epithelia) were subjected to immunohistochemical analysis with the Shh monoclonal antibody. The methylation status of Shh was determined by methylation-specific PCR (MS PCR), involving bisulfate treatment of DNA from 150 tissues followed by amplification using specific primer pairs designed by our group. Shh was completely absent in the upper part of normal gastric epithelia (gastric pit cells), and no significant differences were observed among the lower parts of normal epithelia, chronic gastritis, and intestinal metaplasia. However, Shh expression was significantly elevated in neoplastic lesions, such as carcinoma and high low-grade dysplasia, compared to non-neoplastic lesions. In carcinomas, Shh expression was associated with clinical stage, direct tumor invasion, and differentiation of tumor cells. Methylation of the Shh promoter region was frequent in normal gastric pit cells (11/18, 61.1%), but very rare in gastritis (0/18), intestinal metaplasia (0/19), dysplasia (0/10), and carcinoma (1/63, 1.6%), and correlated significantly with expression (P<0.001). Our results suggested that the increased and constitutive Shh expression is implicated in gastric carcinogenesis, and that promoter methylation may be an important regulatory mechanism of Shh expression.

Suppression of proliferative cholangitis in a rat model by local delivery of paclitaxel.

BACKGROUND: Proliferative cholangitis (PC) leads to biliary stricture, which is the main cause of hepatolithiasis, recurrent cholangitis, and biliary cirrhosis. The aim of this study was to determine whether local delivery of paclitaxel, which inhibits cell proliferation by overstabilization of microtubules, prevents PC in a rat model. METHODS: PC was induced by introducing a fine nylon thread into the bile duct in a rat. Paclitaxel (100 microl of 10, 100, and 1000 micromol/l) or solvent vehicle was administered into the bile duct for 15 min. One week after treatment, histopathologic examination and 5-bromodeoxyuridine (BrdU) labeling of the bile duct were performed. RESULTS: In comparison with the control, the mean thickness of the bile duct was reduced by 29% in the 1000 micromol/l paclitaxel-treated group (2.61 +/- 0.31 microm vs 3.67 +/- 0.25 micro m, P << 0.05). The luminal area increased ( P << 0.0001) and the grade of epithelial-glandular proliferation was decreased ( P << 0.01) as the dose of paclitaxel increased. Ductal fibrosis and inflammatory cell infiltration were similar in both groups. The BrdU labeling index was significantly lower in the paclitaxel-treated group ( P << 0.05). CONCLUSIONS: Local delivery of paclitaxel suppressed PC in a rat model by the inhibition of epithelial-glandular proliferation and may offer an effective therapeutic option for biliary stricture.