Akira Nakahara

Deletion of nuclear factor-E2-related factor-2 leads to rapid onset and progression of nutritional steatohepatitis in mice.

Oxidative stress is a critical mediator in liver injury of steatohepatitis. The transcription factor Nrf2 serves as a cellular stress sensor and is a key regulator for induction of hepatic detoxification and antioxidative stress systems. The involvement of Nrf2 in defense against the development of steatohepatitis remains unknown. We aimed to investigate the protective roles of Nrf2 in nutritional steatohepatitis using wild-type (WT) and Nrf2 gene-null (Nrf2-null) mice. WT and Nrf2-null mice were fed a methionine- and choline-deficient (MCD) diet for 3 and 6 wk, and the liver tissues were analyzed for pathology and for expression levels of detoxifying enzymes and antioxidative stress genes via the Nrf2 transcriptional pathway. In WT mice fed an MCD diet, Nrf2 was potently activated in the livers, and steatohepatitis did not develop over the observation periods. However, in Nrf2-null mice fed an MCD diet, the pathological state of the steatohepatitis was aggravated in terms of fatty changes, inflammation, fibrosis, and iron accumulation. In the livers of the Nrf2-null mice, oxidative stress was significantly increased compared with that of WT mice based on the increased levels of 4-hydroxy-2-nonenal and malondialdehyde. This change was associated with the decreased levels of glutathione, detoxifying enzymes, catalase, and superoxide dismutase activity. Correlating well with the liver pathology, the mRNA levels of factors involved in fatty acid metabolism, inflammatory cytokines, and fibrogenesis-related genes were significantly increased in the livers of the Nrf2-null mice. These findings demonstrate that Nrf2 deletion in mice leads to rapid onset and progression of nutritional steatohepatitis induced by an MCD diet. Activation of Nrf2 could be a promising target toward developing new options for prevention and treatment of steatohepatitis.

Rebamipide Significantly Inhibits Indomethacin-Induced Mitochondrial Damage, Lipid Peroxidation, and Apoptosis in Gastric Epithelial RGM-1 Cells

Nonsteroidal antiinflammatory drugs (NSAIDs) cause complications such as gastrointestinal injury. NSAIDs were recently reported to cause mitochondrial injury: to dissipate the mitochondrial transmembrane potential (MTP), and to induce mitochondrial permeability transition pore (PTP), which liberates cytochrome c. This enzyme generates reactive oxygen species (ROS) thereby triggers caspase cascade and cellular lipid peroxidation, resulting in cellular apoptosis. However, the mechanism of this NSAID-induced MTPs role in cellular apoptosis remains unknown. Rebamipide, an antiulcer drug, is reported to scavenge ROS and to show the protective effects on indomethacin-induced tissue peroxidations. Since cytochrome c and its generation of ROS are involved in indomethacin-induced cellular apoptosis, rebamipide may attenuate mitochondrial damage. The aim of this study was to elucidate whether indomethacin induces both the MTP decrease and cellular apoptosis, and the effect of rebamipide on these phenomena. We examined the effect of rebamipide on 1) MTP change, 2) lipid peroxidation, 3) apoptosis, and 4) caspase activation using gastric mucosal epithelial cell-line treated with indomethacin. With a specially designed fluorescence analyzing microscope system, MTP change, cellular lipid peroxidation, and cellular apoptosis were investigated with the ⋆ following fluorescent dyes, MitoRed, DPPP, and Hoechst 33258, respectively. Indomethacin treatment decreased MTP but increased both cellular lipid peroxidation and cellular apoptosis via caspase 3 and 9 activation. Rebamipide clearly inhibited these phenomena {in vitro}. We demonstrated that fluorescent dyes such as MitoRed, DPPP, and Hoechst 33258 are useful indicators for detecting oxidative cellular injuries in living cells. Rebamipide exerts a protective effect on mitochondrial membrane stability in gastric epithelial cells.

Pancreaticoduodenal artery aneurysms associated with celiac axis stenosis due to compression by median arcuate ligament and celiac plexus

Abstract: Celiac axis stenosis is frequently associated with pancreaticoduodenal artery aneurysms. Although the cause of stenosis was not clear in most of the reported cases, compression of the median arcuate ligament of the diaphragm was found to be responsible for the stenosis in 7 of 42 reported cases of this type of aneurysm. We report a case of aneurysm caused by compression of the median arcuate ligament of the diaphragm and celiac plexus. An asymptomatic 43-year-old Japanese man was admitted with a low echoic lesion in the uncus of pancreas. Computed tomographic scan and angiogram revealed stenosis of the celiac axis and two aneurysms in the inferior posterior pancreaticoduodenal artery. The celiac plexus and median arcuate ligament were divided surgically and normal flow was reestablished in the celiac axis. One of the aneurysms was resected and the afferent artery of the other aneurysm was ligated. In the setting of pancreaticoduodenal artery aneurysm associated with celiac axis stenosis, management of stenosis should be considered in addition to local treatment of the aneurysm. In this context, division of median arcuate ligament and celiac plexus or aorto-celiac bypass may normalize the flows in the pancreaticoduodenal arcade and could be effective in preventing aneurysm reformation.

Endoscopic classification of chronic gastritis based on a pilot study by the research society for gastritis

Background: Various types of classification of gastritis have been proposed, but no plausible classification has been available until now. The Research Society for Gastritis performed a pilot study to establish an endoscopic classification, taking into consideration the following: (i) ease of use; (ii) permitting everyone the common image; and (iii) presence of histopathological evidence.

Clinical Results of Proton-Beam Therapy for Locoregionally Advanced Esophageal Cancer

Purpose:To evaluate the efficacy and safety of proton-beam therapy for locoregionally advanced esophageal cancer.Patients and Methods:The subjects were 51 patients with esophageal cancer who were treated between 1985 and 2005 using proton beams with or without X-rays. All but one had squamous cell carcinoma. Of the 51 patients, 33 received combinations of X-rays (median 46 Gy) and protons (median 36 GyE) as a boost. The median total dose of combined X-rays and proton radiation for these 33 patients was 80 GyE (range 70–90 GyE). The other 18 patients received proton-beam therapy alone (median 79 GyE, range 62–98 GyE).Results:Treatment interruption due to radiation-induced esophagitis or hematologic toxicity was not required for any patient. The overall 5-year actuarial survival rate for the 51 patients was 21.1% and the median survival time was 20.5 months (95% confidence interval 10.9–30.2). Of the 51 patients, 40 (78%) showed a complete response within 4 months after completing treatment and seven (14%) showed a partial response, giving a response rate of 92% (47/51). The 5-year local control rate for all 51 patients was 38.0% and the median local control time was 25.5 months (95% confidence interval 14.6–36.3).Conclusion:The results suggest that proton-beam therapy is an effective treatment for patients with locally advanced esophageal cancer. Further studies are required to determine the optimal total dose, fractionation schedules, and best combination of proton therapy with chemotherapy.ZusammenfassungZiel:Evaluierung der Wirksamkeit und Sicherheit der Protonenstrahlentherapie bei lokoregionar fortgeschrittenem Speiserohrenkrebs.Patienten und Methodik:Es handelte sich um 51 Patienten mit Speiserohrenkrebs, die zwischen 1985 und 2005 mit Protonenstrahlen allein oder kombiniert mit Linac-Photonen behandelt wurden. Bis auf eine Ausnahme hatten alle Patienten ein Plattenepithelkarzinom. Von den 51 Patienten erhielten 33 eine Kombination von Photonen (median 46 Gy) und Protonen (median 36 GyE) als Boost. Die mediane Gesamtdosis der kombinierten Rontgen- und Protonenstrahlung betrug 80 GyE (Spanne 70–90 GyE). Die anderen 18 Patienten wurden ausschlieslich mit Protonenstrahlentherapie behandelt (median 79 GyE, Spanne 62–98 GyE).Ergebnisse:Bei keinem Patienten war eine Behandlungsunterbrechung aufgrund strahleninduzierter Osophagitis oder hamatologischer Toxizitat erforderlich. Die aktuarische Gesamtuberlebensrate der 51 Patienten lag bei 21,1% in 5 Jahren und die mediane Uberlebenszeit 20,5 Monate (95%-Konfidenzintervall 10,9–30,2). Von den 51 Patienten erreichten 40 (78%) innerhalb von 4 Monaten nach Behandlungsende eine komplette Remission und sieben (14%) eine partielle Remission, was eine Ansprechrate von 92% (47/51) ergibt. Die lokale Kontrollrate nach 5 Jahren betrug bei allen 51 Patienten 38,0% und das mediane lokalrezidivfreie Intervall 25,5 Monate (95%-Konfidenzintervall 14,6–36,3).Schlussfolgerung:Die Protonenstrahlentherapie ist eine wirksame Behandlung fur Patienten mit lokal fortgeschrittenem Speiserohrenkrebs. Weitere Studien sind notwendig, um optimale Gesamtdosis, Fraktionierung und die beste Kombination von Protonenstrahlen- mit Chemotherapie zu ermitteln.

Geranylgeranylacetone Protects the Human Gastric Mucosa from Diclofenac-Induced Injury via Induction of Heat Shock Protein 70

Background/Aim: Geranylgeranylacetone (GGA) enhances gastric mucosal protection against nonsteroidal anti-inflammatory drugs by upregulating mucosal heat shock proteins (HSP), but the effects of GGA on the human gastric mucosa have not been well examined. This study was conducted to determine whether a clinical dose of GGA protects the human gastric mucosa from diclofenac (DIC)-induced gastric mucosal injury. Methods: The study group comprised 40 healthy volunteers: 20 subjects were randomly assigned to take either placebo (lactose 1.5 g/day) or GGA (150 mg/day) for 2 weeks (study 1), and 20 subjects were assigned to take DIC (75 mg/day) plus placebo (lactose 1.5 g/day) or DIC (75 mg/day) plus GGA (150 mg/day) for 2 weeks (study 2). In both studies, gastroscopic biopsy specimens were obtained before and after treatment. Mucosal HSP70 expression and DNA damage were analyzed by measuring the levels of HSP70 and 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-OHdG), respectively. Results: In study 1, GGA increased the mucosal HSP70 expression without increasing the 8-OHdG production. In study 2, DIC treatment increased the 8-OHdG production, whereas the combination of GGA and DIC enhanced the HSP70 expression and attenuated the increase in 8-OHdG induced by DIC. Conclusion: The clinical dose of GGA enhanced the gastric mucosal HSP70 expression and inhibited the DIC-induced gastric mucosal damage in humans.

Role of the nrf-2 gene in protection and repair of gastric mucosa against oxidative stress

Helicobacter pylori infection, as well as NSAIDs induce oxidative stress on gastric mucosa, thereby causing mucosal damage and retarding mucosal repair. Cells can survive against chronic oxidative stress by enhancing activities of anti-oxidant enzymes, thereby protecting cells from DNA damage. Recent studies have clearly shown that the gene encoding Nrf-2 (NF-E2 p45-related factor-2) plays an important role in the induction of antioxidant enzymes against oxidative stress. In this paper, we will describe the cellular mechanisms by which the nrf-2 gene stimulates anti-oxidant enzyme activities during exposure to oxidative stress. Secondly, we will also mention the beneficial effects of sulforaphane, an isothiocyanate family which is abundantly included in broccoli sprouts, on gastric mucosa. Sulforaphane stimulates nrf-2 gene-dependent anti-oxidant enzyme activities, thereby protecting cells from oxidative injury. Finally, we will state our perspective on the efficacy of sulforaphane in protection and repair of gastric mucosa against oxidative stress during H. pylori infection.

Neoplastic transformation and induction of H+,K+-adenosine triphosphatase by N-methyl-N′-nitro-N-nitrosoguanidine in the gastric epithelial RGM-1 cell line

N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) induces gastric cancer in animal models. We established an MNNG-induced mutant of the rat murine RGM-1 gastric epithelial cell line, which we named RGK-1, that could be used as an in vitro model of gastric cancer. This cell line showed signs of neoplasia and transformation, in that it lost contact inhibition and formed tumors in nude mice. The mutant cells also expressed parietal cell-specific H+,K+-adenosine triphosphatase (H+,K+-ATPase), which parent RGM-1 did not. The results suggested that parent RGM-1 cells were gastric progenitor cells. This mutant RGK-1 cell line will contribute to future investigation on gastric carcinogenesis and to the development of other pathophysiologic fields.

Expression of human telomerase catalytic subunit gene in cancerous and precancerous gastric conditions

Background and Aims : Telomerase activity is thought to be necessary for cellular immortality and carcinogenesis. The mRNA that encodes the telomerase catalytic subunit (hTERT) has recently been identified, and expression of hTERT mRNA is thought to regulate activation of telomerase. To determine at what stage of carcinogenesis cells begin to express hTERT, we analysed hTERT mRNA expression in gastric carcinoma and precancerous conditions, focusing on chronic gastritis with or without intestinal metaplasia.

Bosentan, a novel synthetic mixed-type endothelin receptor antagonist, attenuates acute gastric mucosal lesions induced by indomethacin and HCl in the rat: Role of endogenous endothelin-1

Endothelin-1 has been reported to be responsible for gastric mucosal damage in various experimental models. We evaluated the role of endogenous endothelin-1 in the pathogenesis of gastric mucosal damage induced by indomethacin and HCl in the rat. Rats were given indomethacin (25 mg/kg) subcutaneously, and 15 min later, 0.2N HCl intragastrically. Gastric mucosal damage, gastric endogenous endothelin-1, and gastric mucosal hemodynamics were measured. The effects of bosentan, a mixed endothelin receptor antagonist, on gastric mucosal integrity and hemodynamics were assessed. Gastric endogenous endothelin-1 was significantly elevated at 20min, gastric mucosal blood flow began to decrease significantly at 25 min, and gastric damage occupied 52.2% of the total glandular mucosa at 135 min after injection of indomethacin. Intragastric pretreatment with bosenthan (5, 10, 30, and 60 mg/kg) significantly attenuated gastric damage, to 26.1%, 7.7%, 3.6%, and 1.6%, respectively, of the total glandular mucosa. Bosentan (60 mg/kg) prevented the initial decrease of blood flow and, even at 135 min, improved blood flow and hemoglobin oxygen saturation significantly. We suggest that indomethacin-induced endogenous endothelin-1 diminishes gastric mucosal blood flow and tissue oxygenation and ultimately causes gastric damage. Endogenous endothelin-1 may play an important role in the pathogenesis of the acute gastric mucosal lesions induced by indomethacin and HCl.