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Biomedical subjects

R Iwakiri

Publications and source records attributed to R Iwakiri.

At least 19 recordsLinked to original sources
PubMed2005

Prevention of the rehaemorrhage of bleeding peptic ulcers: effects of Helicobacter pylori eradication and acid suppression.

AIM: This study aimed to investigate the consequences of Helicobacter pylori eradication and acid suppression on rehaemorrhage caused by bleeding peptic ulcers. METHODS: A total of 320 patients who had been diagnosed with bleeding peptic ulcers between January 1994 and December 2001 were included in the study. Cases between 1994 and 1997, prior to the introduction of eradication therapy, were assigned to group A, whereas those between 1998 and 2001, after the eradication therapy, were assigned to group B. RESULTS: Of the 320 cases, 162 were designated as group A (113 gastric ulcers and 49 duodenal ulcers) and 158 as group B (116 and 42, respectively). Rehaemorrhage occurred in 24 cases (15%) and five cases (3%) in groups A and B, respectively, presenting a significantly decreased rate of rehaemorrhage in group B. Among those without eradication, rehaemorrhage was observed in 15 of 128 cases (12%) that received treatment with histamine(2)-receptor antagonist (famotidine), and 14 of 142 cases (10%) treated with proton-pump inhibitors, with no significant difference between the two. CONCLUSIONS: Helicobacter pylori eradication lowered the rates of rehaemorrhage. Treatment with histamine(2)-receptor antagonist or proton-pump inhibitors did not produce a difference in the rate of rehaemorrhage.

Adult↗
PubMed2003

Effects of antioxidative agents on apoptosis induced by ischaemia-reperfusion in rat intestinal mucosa.

BACKGROUND AND AIM: We have previously demonstrated that ischaemia-reperfusion induces apoptosis in the intestinal mucosa. To evaluate that reactive oxygen species enhanced intestinal apoptosis after ischaemia-reperfusion, we examined whether antioxidants reduced apoptosis. METHODS: Rats were infused through a duodenal tube with antioxidative agents, glutathione, rebamipide and dymethylsulfoxide during 2 h before an ischaemic insult. The superior mesenteric artery was occluded for 60 min, followed by 60 min reperfusion. Apoptosis was evaluated by percentage fragmented DNA (fragmented DNA/total DNA) and immunochemical staining. RESULTS: Increase in apoptosis in the intestinal mucosa after ischaemia-reperfusion was attenuated by intraduodenal infusion of antioxidative agents, but was not completely abolished. CONCLUSION: Scavenging effects of the antioxidative agents attenuated increases in intestinal apoptosis, indicating that oxidative stress after ischaemia-reperfusion plays an important role in induction of apoptosis in the intestinal mucosa.

Alanine↗
PubMed2002

Exogenous cysteine and cystine promote cell proliferation in CaCo-2 cells.

Previous studies have shown that intracellular glutathione, a ubiquitous intracellular thiol, is related to cell proliferation and that cysteine or its disulphide form, cystine, also induces cell proliferation. Cysteine is a thiol containing amino acid and a rate-limiting precursor of glutathione. Therefore, it is still unresolved as to whether the proliferative effect of cysteine or cystine is entirely mediated by a change in the intracellular glutathione status. The objective of this study was to delineate the relationship among cysteine/cystine (thereafter referred to as cyst(e)ine), intracellular glutathione and cell proliferation in the human colon cancer CaCo-2 cell line. CaCo-2 cells were cultured in cyst(e)ine-free Dulbecco's Modified Eagle Medium without serum, and treated with 200 microm cysteine and/or 200-400 microm cystine for 24 h. In the presence of DL-buthionine-[S, R]-sulfoximine (BSO), a glutathione synthesis inhibitor, exogenously administered cyst(e)ine did not change the intracellular glutathione content, but increased the intracellular cysteine as well as cystine level. Addition of exogenous cyst(e)ine following 5 mm BSO treatment significantly increased cell proliferation as measured by 3H-thymidine incorporation and protein content. Cell cycle analyses revealed that cyst(e)ine promoted cell progression from the G1 phase to the S phase. Correspondingly, cyst(e)ine treatment induced expression of cyclin D1 and phosphorylation of retinoblastoma protein (Rb). In conclusion, these data indicate that both cysteine and cystine have proliferative effects in CaCo-2 cells independent of an increase in intracellular glutathione. Induction of cyclin D1, phosphorylation of Rb, and subsequent facilitation of G1-to-S phase transition were involved in the proliferative effect of exogenous cyst(e)ine.

Antimetabolites↗
PubMed2001

Apoptosis induced by ischemia-reperfusion and fasting in gastric mucosa compared to small intestinal mucosa in rats.

The effect of ischemia-reperfusion and 48-hr fasting on apoptosis was characterized in rat gastric mucosa and compared to small intestinal mucosa. Under halothane anesthesia, the celiac artery or superior mesenteric artery in the rat was occluded for 60 min followed by reperfusion. Occlusion of the celiac artery reduced blood flow in the stomach and occlusion of the mesenteric artery reduced blood flow in the small intestine. Additional rats were fasted for 48 hr to evaluate the effect of fasting on mucosal apoptosis. The ratios of fragmented DNA to total DNA, electrophoresis, and immunohistochemical staining were examined after ischemia-reperfusion or fasting. Apoptosis was not induced significantly in the gastric mucosa after ischemia-reperfusion, although it increased dramatically in the intestinal mucosa after ischemia-reperfusion. Further, after 48 fasting, apoptosis was induced in the small intestine, but not in the stomach. These results indicate that rat gastric mucosa is not as sensitive as small intestinal mucosa to ischemia-reperfusion or fasting-induced apoptosis.

Animals↗
PubMed2001

Suppression of apoptosis is responsible for increased thickness of intestinal mucosa in streptozotocin-induced diabetic rats.

Intestinal mucosal growth is a common, but uncharacterized, observation associated with diabetes mellitus. Epithelial homeostasis is balanced by regulation of cell proliferation and cell death. To determine the contribution of apoptosis to the overall maintenance of intestinal growth, we examined intestinal apoptosis in the well-characterized streptozotocin (STZ)-induced diabetes rat model. Rats were injected with STZ (75 mg/kg body weight), thereafter they were allowed free feeding or restricted feeding for 3 weeks. Food intake and intestinal mucosal height were evaluated. In a second experiment, additional groups of animals were injected with STZ and were fed ad libitum for 1 or 3 weeks. Ornithine decarboxylase (ODC) activity, ratio of fragmented DNA to total DNA, electrophoresis of fragmented DNA, and Western blot analysis of caspase-3 were examined. Food intake gradually increased in free-feeding rats after induction of diabetes. Intestinal mucosal height in free-feeding diabetic rats was approximately 25% longer than controls, but this increase in mucosal height was not observed in restricted-fed diabetic rats (25 g/d). ODC activity in intestinal mucosa in diabetic rats did not differ from that of control rats. Percent fragmented DNA of diabetic rats 1 week after STZ injection was significantly lower than that of control rats, and this decrease returned to the control level 3 weeks after STZ treatment. Active form of caspase-3 was attenuated 1 week after drug treatment. Attenuated effect of diabetic rats on intestinal apoptosis did not affect increased apoptosis after ischemia-reperfusion. Suppression of apoptosis in the early days of STZ-induced diabetes was responsible for the increased mucosal height in the small intestine in STZ-induced diabetic animals.

Animals↗
PubMed2001

Programmed cell death in rat intestine: effect of feeding and fasting.

BACKGROUND: The regulation of intestinal cell death by luminal factors is poorly understood. The objectives of this study were to determine whether a diurnal rhythm of intestinal apoptosis exists, and to determine the role that feeding and fasting play in this process. METHODS: Mucosal apoptotic death was measured in fed and 24-h fasted rats and at various times after feeding by DNA fragmentation and in situ immunohistochemical staining (TUNEL). RESULTS: In 24-h fasted rats, 32% of total mucosal DNA was fragmented as compared to 9% in fed animals. In both jejunal and ileal segments, the fragmented DNA exhibited characteristic apoptotic DNA ladders on agarose gels. Immunohistochemical staining revealed significant location of apoptotic cells at the upper third of the intestinal villus. In the duodenum, DNA fragmentation at 6-12 h post feeding was 20% and decreased to 4% at 24 h. In comparison, DNA fragmentation in the jejunum and ileum was low from 0 to 6 h post feeding (2%-9%) and significantly increased at 12 h (18% versus 12%) and 24 h (30% versus 32%), respectively. These results are consistent with a temporal relationship between percent fragmented DNA and time after feeding with greater cell death at longer fasting period. A postprandial rhythm of DNA fragmentation was evident in the jejunum and ileum, in which fragmentation was at a peak between 0900 h and 1200 h. CONCLUSION: Collectively, the data show that initiation of apoptosis in apical enterocytes is coincident with cessation of feeding and commencement of fasting, and is consistent with a rhythm of programmed cell death in these cells that parallels the cyclical pattern of feeding and fasting.

Animals↗
PubMed2001

Induction of mild intracellular redox imbalance inhibits proliferation of CaCo-2 cells.

Intracellular redox status plays a critical role in cell function, such as proliferation. Oxidative stress, which elicits redox imbalance, also affects cell growth. Therefore, it is often difficult to distinguish the effects of redox imbalance from those of oxidative stress. The objective of this study was to determine the role of redox imbalance independent of reactive oxygen species (ROS) production, in proliferation of human colonic CaCo-2 cells. Low concentrations of diamide plus 1,3-bis(2 chloroethyl)-1-nitrosourea (BCNU) increased intracellular GSSG and decreased GSH and the GSH:GSSG ratio. These changes occurred within 30 min, which preceded a decrease in thymidine incorporation at 6 and 24 h. ROS formation was not detected under these conditions. This suppression of cell proliferative activity was attenuated by N-acetyl cysteine, in parallel with restoration of the intracellular GSH redox status. dl-buthionine-[S, R]-sulfoximine (BSO) decreased intracellular GSH level, but did not change the GSH:GSSG ratio. BSO alone had no effect on cell proliferation, but its presence exaggerated the suppressive effect of diamide plus BCNU. Flow cytometric analysis showed that cells were arrested at G1-to-S transition and G2/M phase. Collectively, this study shows that mild intracellular redox imbalance inhibited cell proliferation independent of ROS generation. Moreover, cells with compromised cellular GSH were susceptible to redox imbalance-induced inhibition of proliferation.

Acetylcysteine↗
PubMed2001

Effect of the central nervous system on mucosal growth and apoptosis in the small intestine.

Recently our studies have demonstrated that the central nervous system regulates in part mucosal cell growth and apoptosis in the rat small intestine. Ornithine decarboxylase (ODC) activity is a key enzyme for polyamine synthesis which plays an important role for the intestinal mucosal growth. We have demonstrated that the increase of ODC activity in the duodenum just before the dark period is abolished by truncal vagotomy and that the infusion of 2-deoxy-D-glucose into the third cerebroventricle activates ODC activity in the small intestine. Epithelial homeostasis is balanced by regulation of cell proliferation and cell death. Our preliminary data showed that intestinal mucosal apoptosis decreased in the ventromedial-hypothalamus-lesioned rat. These results indicate that the central nervous system, in addition to local factors, is related to regulation of mucosal homeostasis in the intestinal mucosa.

Animals↗
PubMed2001

Isolation and characterization of Desulfitobacterium sp. strain Y51 capable of efficient dehalogenation of tetrachloroethene and polychloroethanes.

A strict anaerobic bacterium, strain Y51, was isolated from soil contaminated with tetrachloroethene (PCE). Strain Y51 is capable of very efficiently dehalogenating PCE via trichloroethene (TCE) to cis-1,2-dichloroethene (cis-1,2-DCE) at concentrations as high as 960 microM and as low as 0.6 microM. Strain Y51 was gram-negative, motile with some lateral flagella, and curved rod-shaped. On the basis of the 16S rDNA sequence, the organism was identified to be a species within the genus Desulfitobacterium. Strain Y51 also had dehalogenation activities toward polychloroethanes such as hexa-, penta-, and tetrachloroethanes, from which dichloroethenes were produced as the final products. The cell extracts mediated the dehalogenation of PCE with reduced methyl viologen as an electron carrier at the specific rate of 5.0 nmol min(-1) mg cell protein(-1) (pH 7.2, 37 degrees C). Dehalogenation was highly susceptible to air oxidation, and to potential alternative electron acceptors such as nitrite or sulfite.

Bacillaceae↗
PubMed2001

[A case of malignant lymphoma concomitant with multiple myeloma].

A 75-year-old woman was referred to us because of cough, high fever and skin erythema in April 1999. Malignant lymphoma (diffuse mixed cell type) was previously diagnosed in 1990 and she achieved complete remission after treatment with a series of CHOP regimen treatments. In 1998, multiple myeloma (IgG lambda type) was diagnosed and she was treated with a combination of melphalan and prednisolone. On physical examination, superficial lymphadenopathy and skin erythema were noted. Biclonal gammopathy (IgG kappa/lambda) was shown in serum, and Bence Jones protein in urine. Computed tomography showed pleural effusion and swelling of paraaortic lymph nodes. The bone marrow examination showed an increased number of abnormal plasma cells (19.2%) and no evidence of lymphoma. Left axillary lymph node biopsy revealed that she had non-Hodgkin's lymphoma (immunoblastic lymphadenopathy-like T cell lymphoma). She was treated with the CHOP regimen at reduced doses for both diseases. The lymphoadenopathy reduced after 6 courses of CHOP and 4 courses of CHOPE (CHOP + VP16), however, she had bone pain on November 1999 and received treatment with MCNU-VMP (MCNU + VDS + L-PAM + PSL). Her rib pain improved, but she died of systemic infection of herpes zoster virus. We report here a rare case of malignant lymphoma concomitant with multiple myeloma.

Aged↗
PubMed2000

Loss of diurnal variation in ornithine decarboxylase and apoptosis in small intestine of Mongolian gerbils.

The aim of this study was to examine the diurnal variations in ornithine decarboxylase (ODC) activity and apoptosis in the small intestinal mucosa of Mongolian gerbils. First, the feeding, drinking, and ambulatory patterns of the gerbils were recorded. The results indicated that Mongolian gerbils lost diurnal cyclicity in feeding, drinking, and ambulatory patterns. Second, ODC activity and apoptosis in the intestinal mucosa of gerbils were characterized by measurements at four time points (11:00, 17:00, 23:00, and 05:00 h; light period, 08:00-20:00 h). Apoptosis was evaluated in terms of percent fragmented DNA (fragmented DNA/total DNA). Neither ODC activity nor apoptosis showed diurnal variation in the jejunal mucosa of the Mongolian gerbils. In 48-h fasted gerbils, ODC activity in the intestinal mucosa decreased, but this activity increased significantly 2 h after refeeding; percent fragmented DNA increased in the intestinal mucosa, and returned to the control level 2 h after refeeding. These results indicate that postprandial local nutrients are an important factor in regulating diurnal variation in ODC activity and apoptosis in the small intestine of gerbils.

Animals↗
PubMed2000

Endoscopic injection sclerotherapy for esophageal varices prolonged survival of patients with hepatocellular carcinoma complicating liver cirrhosis.

BACKGROUND: A prospective controlled study was performed between 1982 and 1991 to evaluate the efficacy of endoscopic injection sclerotherapy (EIS) in patients with esophageal varices complicated by hepatocellular carcinoma and liver cirrhosis. METHODS: The study included 83 patients with esophageal varices, hepatocellular carcinoma, and liver cirrhosis. Forty-three patients (group 1) underwent prophylactic EIS or emergent EIS for bleeding varices. EIS was performed weekly 4 to 6 times until the varices disappeared. The remaining 40 patients (group 2) underwent conservative therapy and did not undergo EIS. Survival rates were compared between the 2 groups. RESULTS: During the 5-year observational period, all patients who did not undergo EIS died. Sixteen in group 2 (40.0%) died of gastrointestinal bleeding including ruptured esophageal varices. In contrast, patients treated with EIS survived significantly longer (p<0.001). Nine patients (20.9%) treated with EIS experienced gastrointestinal bleeding as a result of which 5 (11.6%) died. EIS prolonged survival in patients classified as Child's A or B but did not affect survival in patients with Child's C hepatic function. EIS was effective in prolonging survival in patients with hepatocellular carcinomas smaller than 5 cm. However, EIS had no effect in patients with hepatocellular carcinomas that were larger than 5 cm. EIS prolonged survival only for patients with nodular hepatocellular carcinoma and had no effect in patients with massive and diffuse hepatocellular carcinoma. Further, EIS prolonged survival only for patients who did not have portal vein thrombosis. CONCLUSION: Based on this prospective study, we concluded that EIS was effective in prolonging the survival period of a select subset of patients with hepatocellular carcinoma.

Aged↗
PubMed2000

Histaminergic effect on apoptosis of rat small intestinal mucosa after ischemia-reperfusion.

This study aimed to examine the relationship between a harmful effect of histamine and apoptosis following ischemia-reperfusion in the rat intestine. The superior mesenteric artery was occluded for 60 min followed by reperfusion for 60 min. Rats were infused with H1-receptor antagonist (chlorpheniramine maleate) or H2-receptor antagonist (cimetidine). Additional rats were pretreated with aminoguanidine (100 mg/kg). Percent apoptosis in the intestinal mucosa increased after reperfusion, but neither H1 nor H2 antagonists had any effect on apoptosis. Aminoguanidine pretreatment inhibited activity of diamine oxidase and increased the plasma histamine concentration. Aminoguanidine attenuated the increase in mucosal apoptosis following reperfusion. Apoptosis induced by an ischemic insult to the intestinal mucosa was not related to an undesirable effect of histamine. Attenuation of increased intestinal apoptosis might be due to increased plasma histamine level and/or other pharmacological action of aminoguanidine, including inhibition of inducible nitric oxide synthase.

Animals↗
PubMed2000

[Simple antireflux measures for management of gastroesophageal reflux disease].

It is widely accepted that proton pump inhibitors are the most effective therapy for management of gastroesophageal reflux disease. H2-receptor antagonists, prokinetic agents, and antacids are used in treatment of gastroesophageal reflux disease. In addition to these medical treatments, beneficial effects of simple anti-reflux measures on management of gastroesophageal disease are evaluated. Simple anti-reflux measures include elevation of the head of the bed, weight loss, reduced food intake, and the avoidance of precipitating foods and drugs. In this chapter, we summarized the utility of these simple anti-reflux measures for management of gastroesophageal reflux disease.

Diet↗