Acceleration of gastric ulcer healing by omeprazole in portal hypertensive rats. Is its action mediated by gastrin release and the stimulation of epithelial proliferation?

BACKGROUND: Gastric ulcer healing is delayed in patients with portal hypertension (PHT) and often responds poorly to histamine H(2) blockers. Although proton pump inhibitors are more effective anti-ulcer agents, there is little information regarding their efficacy for gastric ulcer in cases of PHT. Therefore, we investigated the effects of a proton pump inhibitor, omeprazole, on the healing of acetic-acid-induced gastric ulcer in PHT rats. METHODS: Animals studied were 80 male Sprague-Dawley rats aged 7 weeks, of which half underwent two-staged portal vein ligation (PHT rats) and half underwent a sham operation (SO rats). Gastric ulcers were induced by acetic acid. Starting from day 4 after ulcer induction, rats received omeprazole or vehicle orally (50 mg/kg) for 5 or 10 days. Ulcer area, proliferating cell nuclear antigen labelling index (PCNA LI), and serum gastrin levels were recorded. RESULTS: PHT significantly inhibited epithelial cell proliferation and delayed gastric ulcer healing as indicated by a decreased PCNA LI at the ulcer margin and almost 2-fold larger ulcer area in PHT versus SO rats 14 days after ulcer induction. Ten-day treatment with omeprazole (vs. vehicle) significantly accelerated ulcer healing to a similar extent in both PHT and SO rats. Serum gastrin levels were significantly higher in PHT rats than in SO rats following treatment with omeprazole. Omeprazole (vs. vehicle) restored the decreased PCNA LI at the ulcer margin in PHT rats to that noted in SO rats. CONCLUSIONS: In PHT rats, omeprazole accelerates gastric ulcer healing, stimulates epithelial cell proliferation at the ulcer margin, and increases serum gastrin levels. Since gastrin is a potent stimulator of gastric epithelial cell proliferation, increased serum gastrin levels may be an important factor in omeprazole-induced stimulation of epithelial cell proliferation and acceleration of gastric ulcer healing in conditions of PHT.

Expression of serum response factor in normal rat gastric mucosa.

Serum response factor (SRF) is a transcription factor that is involved in cell proliferation, muscle and neuron development and maintenance. Its expression in gastric mucosa remains unknown. In this study we demonstrated that SRF is expressed in normal rat gastric tissue as two isoforms and localized mainly to smooth muscle cells of muscularis mucosae and its extensions into the lamina propria, to muscularis propria, and musculature of the vascular system. To a lesser extent, SRF is also expressed in the gastric epithelium of the mucosal neck area (proliferative zone) and in the endothelial cells of microvessels. These data suggest that the main role of SRF in normal gastric tissue is to maintain muscular support and contraction and possibly epithelial regeneration.

Effects of carbon dioxide pneumoperitoneum on hemodynamics in cirrhotic rats.

BACKGROUND: The aim of our study was to investigate the effect of carbon dioxide pneumoperitoneum on systemic and splanchnic hemodynamics in cirrhotic rats. METHODS: Sprague-Dawley rats (n = 80) were used in this study. Liver cirrhosis was induced by thioacetamide administration intraperitoneally (200 mg/kg body weight, twice a week for 16 weeks). The radioactive microsphere method was used to measure systemic and regional hemodynamic parameters before, 1 h after the start, and 1 h after the release of pneumoperitoneum. RESULTS: Splanchnic blood flow and cardiac index were significantly depressed during pneumoperitoneum in liver cirrhosis and control groups, but no significant differences were seen between the two groups. In both groups, portal venous inflow decreased and hepatic arterial blood flow increased significantly during pneumoperitoneum. However, during pneumoperitoneum, total hepatic blood flow as a percentage of its value before pneumoperitoneum was lower in cirrhotic rats (71.0%) than in control rats (91.9%) (p <0.05, Mann-Whitney U-test). CONCLUSIONS: Carbon dioxide pneumoperitoneum markedly decreases total hepatic blood flow in cirrhotic rats due to the impaired hepatic arterial buffer response. Liver function should be carefully controlled in cirrhotic patients after laparoscopic surgery with pneumoperitoneum.

Defective mitogen-activated protein kinase (ERK2) signaling in gastric mucosa of portal hypertensive rats: potential therapeutic implications.

Portal hypertensive (PHT) gastropathy is a frequent, serious complication of liver cirrhosis. PHT gastric mucosa has numerous abnormalities such as reduced mucosal potential differences, reduced surface oxygenation, and increased susceptibility to injury caused by alcohol, aspirin, and other noxious factors. Because such mucosal injury is initially mediated by oxygen free radicals, and because mitogen-activated protein (MAP) kinase (ERK2) protects against cellular stress and induces cell proliferation, we postulated that oxidative stress-induced ERK2 activation is defective in PHT gastric mucosa. Here we show that in PHT gastric mucosa, ERK2 activation by oxidative stress is impaired. This impairment is mediated by overexpression of MAP kinase phosphatase-1 (MKP-1), which results from the underlying and continual oxidative state associated with portal hypertension, and is ameliorated by inhibiting MKP-1. Furthermore, we found that supplementing vitamin E, a free radical scavenger, reduces the oxidative state in PHT gastric mucosa, normalizes MKP-1 expression, and thereby reverses impairment of oxidative stress-induced ERK2 activation. Finally, we show that orally administered vitamin E completely reverses the increased susceptibility of PHT gastric mucosa to alcohol injury. Our findings point to a new molecular and mechanistic basis for PHT gastropathy and provide a new therapeutic modality for protection of PHT gastric mucosa.

Gene therapy for gastric ulcers with single local injection of naked DNA encoding VEGF and angiopoietin-1.

BACKGROUND & AIMS: Angiogenesis, formation of new capillary blood vessels, is crucial for gastroduodenal ulcer healing because it enables delivery of oxygen and nutrients to the healing site. Because angiogenesis is stimulated by vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang1), we studied whether local gene therapy with nonviral DNA encoding VEGF and/or Ang1 into the ulcer base could accelerate ulcer healing through enhanced angiogenesis. METHODS: Gastric ulcers were induced in rats by acetic acid applied to the serosal surface of the stomach, and the site around the ulcer was injected with nonviral plasmid-encoding full-length complementary DNA (cDNA) of human recombinant (rh) VEGF165, rhAng1, or their combination. For some studies, neutralizing anti-VEGF antibody was administered. RESULTS: Single local injection of plasmids encoding VEGF165 and Ang1 significantly increased neovascularization and accelerated ulcer healing. A neutralizing anti-VEGF antibody significantly reduced the acceleration of ulcer healing resulting from the treatment. Coinjection of both plasmids encoding rhVEGF165 and rhAng1 resulted in formation of more mature vessels and to more complete restoration of gastric glandular structures within the ulcer scar. However, this did not result in further reduction of ulcer size. CONCLUSIONS: VEGF and Ang1 gene therapy, with limited duration of target gene expression, significantly accelerates gastric ulcer healing. Coinjection of both plasmids leads to more complete structural restoration. Inhibition of accelerated healing by a neutralizing anti-VEGF antibody indicates an essential role for VEGF and enhanced angiogenesis in ulcer healing.

NSAIDs inhibit the activation of egr-1 gene in microvascular endothelial cells. A key to inhibition of angiogenesis?

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, indomethacin (IND), ibuprofen and newer cyclooxygenase-2 selective NSAIDs (e.g. celecoxib) delay gastric ulcer healing partly through the inhibition of angiogenesis, but the molecular mechanisms involved are not fully elucidated. Effective angiogenesis is required for ulcer healing to supply oxygen and nutrients to the healing site. The early growth response factor (Egr-1) is a transcription factor, which is rapidly activated by a variety of extracellular signals or tissue injury and is important for angiogenesis to occur. This study aimed to determine whether indomethacin (IND) and/or the selective COX-2 inhibitor, NS-398, interfere with egr-1 gene expression in human microvascular endothelial cells (HMVEC) in response to vascular endothelial growth factor (VEGF) stimulation. HMVEC were treated with 0.5 mM IND or 100 microM NS-398 for 16 h, and then VEGF (10 ng/ml) or vehicle was added. Egr-1 mRNA and protein expression levels were determined by RT-PCR and Western-blotting, respectively. VEGF treatment caused a significant elevation of Egr-1 mRNA (261+/-21%, P<0.001) and protein expression (174+/-15%, P<0.01) vs. vehicle. IND pre-treatment significantly inhibited VEGF-induced Egr-1 mRNA expression by 29+/-4% (P<0.01) and protein expression by 41+/-8% (P<0.05). NS-398 inhibited VEGF-induced Egr-1 mRNA and protein expression by 23+/-3% and 35+/-4%, respectively (both P<0.01). Since transcriptional activation of egr-1 is responsible for expression of proteins involved in proliferation of endothelial cells essential for angiogenesis, these results provide a new mechanism for NSAIDs' interference with angiogenesis.

Despite activation of EGF-receptor-ERK signaling pathway, epithelial proliferation is impaired in portal hypertensive gastric mucosa: relevance of MKP-1, c-fos, c-myc, and cyclin D1 expression.

Portal hypertensive (PHT) gastric mucosa has increased susceptibility to injury and impaired mucosal healing. Our previous study demonstrated increased ERK activation and MAP kinase phosphatase-1 (MKP-1) overexpression in PHT gastric mucosa. However, it remains unknown which tyrosine kinase receptors are involved in ERK activation and whether ERK activation results in increased cell proliferation. We examined whether EGF receptor (EGF-R) is involved in ERK activation and whether ERK activation triggers epithelial proliferation in PHT gastric mucosa. In gastric mucosa of PHT and sham-operated (SO) rats we studied: (1) EGF-R mRNA and protein expression as well as phosphorylation and membrane protein tyrosine kinase (PTK) activity; (2) ERK2 phosphorylation and activity; (3) MKP-1 mRNA and protein; (4) c-fos, c-myc and cyclin D1 mRNAs, and gastric epithelial proliferation. In PHT gastric mucosa: (1) EGF-R mRNA, protein and phosphorylation and membrane PTK activity were all significantly increased by 38%, 49%, 43% and 49%, respectively; (2) ERK2 phosphorylation and activity were significantly increased by 40% and 50 %, respectively; (3) MKP-1 mRNA and protein expression were significantly increased by 27% and 34%, respectively. In contrast, (4) c-fos, c-myc, and cyclin D1 mRNAs expression were all significantly decreased in PHT gastric mucosa by 36%, 33%, and 49%, respectively, and cell proliferation was significantly lower that in SO rats (11% in PHT vs. 18% in SO). These results suggest that in PHT gastric mucosa, ERK activation is mediated through EGF-R upregulation, but the gastric epithelial proliferation is impaired, possibly by MKP-1 overexpression, leading to reduction of c-fos, c-myc and cyclin D1.

Activation of hypoxia inducible factor-1alpha in gastric mucosa in response to ethanol injury: a trigger for angiogenesis?

Gastric mucosal injury triggers angiogenesis and activation of VEGF expression, but the mechanism(s) of VEGF gene activation are not known. In some tissues (e.g. myocardium), hypoxia triggers activation of hypoxia-inducible factor-1alpha (HIF-1alpha), a transcription factor known to activate VEGF gene expression. This study was aimed to determine whether hypoxia and/or alcohol injury may induces HIF-1alpha in gastric mucosa. Normal rat gastric tissue was incubated in organ culture under either hypoxic or normoxic conditions for 6hrs. Rats received, intragastrically, either saline or alcohol and gastric mucosa bordering necrosis was obtained at 1-24hrs. HIF-1alpha mRNA and protein were determined by RT-PCR and Western-blot analysis. HIF-1alpha and VEGF proteins were localized by immunostaining. Incubation of normal gastric mucosa under hypoxia caused a significant elevation of HIF-1alpha mRNA (20+/-2%, p<0.05) and protein (262+/-15%, p<0.005) vs. normoxia. Following alcohol injury, gastric mucosa bordering necrosis demonstrated a significant increase in HIF-1alpha mRNA at 3 and 6hrs (40+/-4%, 19+/-2%; p<0.05), and protein (>300+/-16%; p<0.02 at all time points; highest at 1-3hrs). HIF-1alpha signal was detected in regenerating mucosal microvessels, where it co-localized with VEGF. Since HIF-1alpha initiates transcription of VEGF mRNA, HIF-1alpha activation by ethanol-induced injury is likely responsible for activation of VEGF gene and induction of angiogenesis.

Transvenous sclerotherapy for huge oesophagogastric varices using open injection sclerotherapy.

BACKGROUND: The optimum procedure for long-term management of oesophagogastric varices when endoscopic sclerotherapy or ligation fails is yet to be established. This report describes a new procedure for treating huge oesophagogastric varices by open injection sclerotherapy. METHODS: Twenty-three patients with huge oesophagogastric varices underwent laparotomy and devascularization of the upper stomach with splenectomy. The left gastric vein was catheterized for repeated injection of 5 per cent ethanolamine oleate during the postoperative period. RESULTS: In all patients, the varices were eradicated after a mean of 3 sessions of sclerotherapy. There were no deaths or major complications during the mean follow-up period of 41 months. Small recurring varices in two patients were treated successfully by endoscopic sclerotherapy and interventional radiology. CONCLUSION: Open injection sclerotherapy is an effective and safe procedure for the treatment of huge oesophagogastric varices.

The efficacy of laparosonic coagulating shears for arterial division and hemostasis in porcine arteries.

BACKGROUND: Recently, the laparosonic coagulating shears (LCS) have been used widely in laparoscopic surgery. In the current study, the usefulness of LCS for arterial division and hemostasis was examined in porcine arteries. METHODS: Porcine arteries of several diameters (1, 3, and 5 mm) were removed and divided using LCS with different blade modes: shear, blunt, and flat. The division time and bursting pressure were registered. Additionally, divided sections stained by the Azan-Mallory method were observed microscopically. RESULTS: The division time was dependent on the blade modes used. With the flat mode, the bursting pressure of 5-mm arteries was significantly higher than the bursting pressure with shear and blunt modes. Histologically, cavitation and mild degeneration of the vessel walls occurred adjacent to the cutting edge. CONCLUSION: The LCS is a safe and useful device for arterial division and hemostasis for 5-mm arteries if an adequate blade mode is used.

Delayed healing of acetic-acid-induced gastric ulcer in portal hypertensive rats.

The aim of the present study was to determine the effect of portal hypertension on the healing of gastric ulcers in rats. Portal hypertension was induced by staged portal vein ligation. Sham-operated (SO) rats served as controls. Gastric ulcers were induced by application of acetic acid to the serosal surface of the stomach. Healing was assessed by determining the ulcer area on days 3, 7, and 10 after ulcer induction. Epithelial proliferation at the ulcer margin was assessed by evaluating the proliferating cell nuclear antigen labeling index. On days 3 and 7, the proliferating cell nuclear antigen labeling index was lower in portal hypertensive (PHT) rats than in SO rats. On day 10, the ulcer area in PHT rats was nearly twice that in SO rats (4.13 +/- 0.29 vs. 2.28 +/- 0.22 mm(2), p < 0.05). These results suggest that portal hypertension may delay gastric ulcer healing. Furthermore, the inhibition of epithelial proliferation at the ulcer margin may be involved in the delayed healing in portal hypertension.

The role of nitric oxide in the inhibition of gastric epithelial proliferation in portal hypertensive rats.

BACKGROUND/AIM: Portal hypertension is associated with inhibition of gastric epithelial proliferation and increased gastric nitric oxide synthase activity. Whether the nitric oxide inhibits gastric epithelial proliferation is unclear. METHODS: Portal vein ligation was performed to induce portal hypertension in rats. The rats were treated for 7 days with either vehicle or N(G)-nitro-L-arginine methyl ester (L-NAME) at 5 mg/kg or 25 mg/kg doses (gastric gavage, twice a day). Sham-operated rats treated with vehicle served as controls. Hemodynamic parameters were measured using radiolabeled microspheres in anesthetized animals. Gastric epithelial proliferation was assessed by evaluating the proliferative cell nuclear antigen labeling index. RESULTS: The cardiac index and gastric fundic blood flow were higher, and the gastric fundic proliferative cell nuclear antigen labeling index was lower in the portal hypertensive rats than in the controls. In portal hypertensive rats, the 5 mg/kg dose of L-NAME decreased the cardiac index and increased the gastric fundic proliferative cell nuclear antigen labeling index to levels similar to those found in the controls, but did not affect gastric fundic blood flow significantly. The 25 mg/kg dose of L-NAME further decreased both the cardiac index and the gastric fundic blood flow, but did not affect the gastric proliferative cell nuclear antigen labeling index significantly. CONCLUSIONS: In portal hypertensive rats, the correction of systemic hyperdynamic circulation by NO inhibition is associated with normalization of gastric epithelial proliferation. Excessive nitric oxide may inhibit gastric epithelial proliferation in portal hypertension.

Impaired adaptive cytoprotection to ethanol-induced damage in gastric mucosa of portal hypertensive rats.

Portal hypertension predisposes gastric mucosa to increased damage by noxious agents. Adaptive cytoprotection has not been studied in portal hypertensive gastric mucosa. We evaluated adaptive cytoprotection in the gastric mucosa of portal hypertensive rats by exposure to ethanol. The injury index (percent gross lesions) was significantly higher in portal hypertensive rats than in sham-operated rats. The ratio of adaptive cytoprotection, calculated as the degree of decrease in the injury index caused by pre-absolute-ethanol administration of 20% ethanol, was significantly impaired in portal hypertensive rats. Basal levels of gastric mucosal hexosamine were lower in portal hypertensive rats than in controls, and a blunted response to 20% ethanol was associated with portal hypertension. Nitric oxide inhibition (L-NAME, 5 mg/kg) reduced the ratio of adaptive cytoprotection in sham-operated but not in portal hypertensive rats. These results suggest that impaired adaptive cytoprotection in portal hypertensive gastric mucosa may be caused by blunted mucus production.

Laparoscopic resection of a pancreatic mucinous cystadenoma using laparosonic coagulating shears.

A 71-year-old woman with a solitary mucinous cystic neoplasm of the pancreatic tail complained of back pain. A laproscopic distal pancreatectomy was performed. Laparosonic coagulating shears (LCS) were employed for dissection of the surrounding tissue and transection of the pancreas. The main pancreatic duct was clipped. There was no evidence of bleeding or pancreatic leakage from the transection surface. Pathologic examination showed the tumor to be a mucinous cystadenoma. The postoperative course was uneventful. The LCS was effective in this application.

Laparoscopic cholecystectomy using the abdominal wall lift in a cardiac patient.

We present a case report of a patient with impaired cardiac function after aortic valve replacement and open mitral commissurotomy who underwent a laparoscopic cholecystectomy for cholecystolithiasis. In preventing reduced cardiac output due to pneumoperitoneum, the laparoscopic operative procedure was performed using the abdominal wall lift. Cardiac function was continuously evaluated by transesophageal echocardiographic examination and remained stable during the surgery. Because of the patient's co-existing chronic atrial fibrillation and prosthetic aortic valve, perioperative anticoagulation management was carried out. The patient's post-operative course was uneventful, and he was discharged on the 7th post-operative day.

Laparoscopic enucleation of a pancreatic insulinoma: report of a case.

We report herein the case of a 48-year-old Japanese woman in whom a pancreatic insulinoma was successfully treated by laparoscopic enucleation. The patient presented after developing episodic neurohypoglycemic symptoms, and an insulinoma in the pancreatic tail, 1.0 cm in diameter, was diagnosed by the results of biochemical and radiological examinations. A laparoscopic intraoperative ultrasonogram demonstrated a solitary hypoechogenic tumor in the pancreatic tail. After the tail and body of the pancreas with the spleen were mobilized, laparoscopic enucleation was performed without any complications. The total operative time was 225min and the estimated blood loss was 20 ml. Serial blood sugar measurements demonstrated a sharp rise in blood sugar levels at the time of enucleation. The patient's postoperative course was uneventful, and she was discharged on the seventh postoperative day. She has remained well for 33 months following surgery without any hypoglycemic symptoms.

Glucagon and insulin metabolism in cirrhotic patients.

BACKGROUND/AIMS: The aim of this study was to investigate glucagon and insulin metabolism in order to clarify the mechanisms that lead to hyperglucagonemia and hyperinsulinemia in cirrhosis. METHODOLOGY: Splanchnic output and metabolic clearance rates were studied in 16 cirrhotic patients and 5 non-cirrhotic controls. Splanchnic glucagon and insulin output into the portal circulation were calculated by the difference between portal venous and systemic arterial concentration multiplied by portal plasma flow. The metabolic clearance rate was calculated as the ratio of output to systemic arterial concentration. Portal blood flow was measured by continuous local thermodilution. RESULTS: Arterial glucagon levels were higher in cirrhotics than in controls. Glucagon output was triple of that found in controls (52.4 +/- 7.0 vs 17.7 +/- 2.9 ng/min, p < 0.05). Both groups exhibited similar metabolic clearance rates of glucagon. Systemic arterial insulin values were higher in cirrhotics than in non-cirrhotics. Insulin output was not significantly different between the two groups. However, metabolic clearance of insulin in cirrhotics was reduced to one half of the rate found in controls (237.0 +/- 39.8 vs. 450.5 +/- 17.5 mL/min, p < 0.05). CONCLUSIONS: Hyperglucagonemia in cirrhotic patients results from increased pancreatic output, while hyperinsulinemia results from decreased insulin clearance.

Laparoscopic cholecystectomy in patients undergoing anticoagulant therapy.

We recently performed a laparoscopic cholecystectomy on three patients receiving preoperative oral anticoagulant therapy. The patients requiring anticoagulants for pre-existing cardiac conditions have the following risks at surgery: thromboembolism, hemorrhage, endocarditis, and cardiopulmonary dysfunction. In patients receiving anticoagulant therapy, one must thus maintain a balanced international normalized ratio of the prothrombin time to prevent thromboembolism or hemorrhage. Warfarin sodium was discontinued preoperatively in all patients. Heparin sodium was individualized according to each patient's risk of thromboembolism. As a result, these patients all underwent a laparoscopic cholecystectomy without complications. Attention was paid to achieve hemostasis in the operative field and the trocar inserted sites during the procedure. The administration of warfarin sodium was resumed on the first postoperative day in all patients. Restarting warfarin sodium early also helps to simplify postoperative management. A broad spectrum of antibiotic therapy was also used to reduce the risk of endocarditis. Each patient's cardiopulmonary function was carefully monitored. The minimal invasion experienced during a laparoscopic cholecystectomy may thus facilitate the management of gallstones in patients receiving systemic anticoagulation treatment based on the findings of this limited series.

Comparison of pneumoperitoneum and abdominal wall lifting as to hemodynamics and surgical stress response during laparoscopic cholecystectomy.

BACKGROUND: Impairments in hemodynamics during pneumoperitoneum (PP) have been noted. This study compared changes in hemodynamics and surgical stress response with PP and abdominal wall lifting (AWL) during laparoscopic cholecystectomy. METHODS: Twenty patients with symptomatic cholecystolithiasis were assigned to PP (n = 10) or AWL (n = 10). Cardiac output (CO), stroke volume (SV), and ejection fraction (%EF) were measured by transesophageal echocardiography. Clearances of para-aminohippurate (CPAH) and sodium thiosulfate (CSTS) were determined as measures of renal function. Levels of interleukin-6, C-reactive protein, white cell count, and neutrophil elastase were evaluated as indicators of surgical stress. RESULTS: In the PP group, CO, SV, and %EF were depressed significantly during pneumoperitoneum. Immediately after and 15 min after insufflation, the CPAH and CSTS were decreased by 78.0% and 73.8%, respectively. None of the hemodynamic parameters changed significantly in the AWL group. Surgical stress response was not different significantly between the two groups. CONCLUSIONS: In contrast to pneumoperitoneum, AWL did not alter cardiac function or renal hemodynamics. AWL may be useful in patients with cardiovascular or renal disorders.