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Biomedical subjects

Michiro Otaka

Publications and source records attributed to Michiro Otaka.

36 records · Page 2Linked to original sources
PubMed2005

Gastric small cell carcinoma with marked response to neoadjuvant chemotherapy.

We report a patient with gastric small cell carcinoma (SCC) who showed a marked response to neoadjuvant chemotherapy. The patient was a 72-year-old Japanese man who was admitted because of epigastralgia. Subsequent examination revealed the presence of advanced gastric carcinoma in the lesser curvature of the lower body of the stomach, with multiple abdominal lymph node metastases. Endoscopic biopsy specimens from the tumor revealed SCC with moderately differentiated adenocarcinoma. The patient received neoadjuvant chemotherapy consisting of carboplatin (400 mg/m2, for 1 day), epirubicin (27 mg/m2, for 1 day), etoposide (70 mg/m2, for 3 days), and 5-fluorouracil (330 mg/m2, for 11 days). Clinically, the primary tumor and lymph node metastases were markedly reduced. Subsequently the patient underwent curative surgery and was alive without recurrence for more than 3 years after the surgery.

Aged↗
PubMed2005

Rolipram, a specific type IV phosphodiesterase inhibitor, ameliorates aspirin-induced gastric mucosal injury in rats.

Inhibition of type IV phosphodiesterase (PDE IV) activity reduces the production of various proinflammatory cytokine and suppresses neutrophil activation. Nonsteroidal anti-inflammatory drugs such as aspirin induce gastric mucosal lesions. In the pathogenesis of aspirin-induced gastric mucosal lesion, the contributions, of activated inflammatory cells and proinflammatory cytokine production are critical. The specific PDE IV inhibitor rolipram is known to be a potent inhibitor of inflammation by increasing intracellular cyclic AMP in leukocytes. The aim of the present study was to determine whether rolipram can ameliorate aspirin-induced gastric mucosal lesions in rats and whether the agent can inhibit the inrease in neutrophil accumulation and the production of proinflammatory cytokines. Gastric lesions were produced by administration of aspirin (200 mg/kg) and HCI (0.15 N; 8.0 ml/kg). Rolipram was injected 30 min before aspirin administration. The tissue myeloperoxidase concentration in gastric mucosa was measured as an indicat or of neutrophil infiltration. The gastric mucosal concentrations of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) were determined by ELISA. The intragastric administration of aspirin induced multiple hemorrhagic erosions in rat gastric mucosa. Gastric mucosal lesions induced by aspirin were significantly inhibited by treatment with rolipram. The mucosal myeloperoxidase concentration was also suppressed by rolipram. Increases in the gastric content of TNF-alpha and IL-1beta after aspirin administration were inhibited by pretreatment with rolipram. We demonstrated that the specific type IV PDE inhibitor, rolipram, could have a potent antiulcer effect, presumably mediated by its anti-inflammatory properties.

Animals↗
PubMed2005

Oncogenic potential of MEK1 in rat intestinal epithelial cells is mediated via cyclooxygenase-2.

BACKGROUND & AIMS: The mitogen-activated protein kinase/extracellular signal-regulated protein kinase kinase (MEK) pathway plays an important role in the regulation of cell growth and differentiation. Constitutively active components of the MEK signaling cascade can induce oncogenic transformation in many cell systems. Downstream MEK signaling also plays an important role in the regulation of cyclooxygenase-2 (COX-2), which is known to be involved in colorectal cancer. Therefore, we determined the role of COX-2 on the oncogenic potential of MEK1 in nontransformed rat intestinal epithelial cells. METHODS: Constitutively active MEK1 (CA-MEK) mutant transfected rat intestinal epithelial cells were established and tested for their ability to grow in soft agar and form tumors in vivo. The effect of CA-MEK on sodium butyrate (NaB)-induced apoptosis was evaluated by the Annexin V assay. The transcriptional activity and posttranscriptional stability of the COX-2 gene was determined by transient transfection with COX-2 reporter variants and by Northern analysis. To address the role of COX-2 in tumor growth in vivo, xenografted mice were treated with celecoxib (100 mg/kg) or vehicle. RESULTS: CA-MEK transfected RIE-1 and IEC-6 cells formed colonies in soft agar and tumors in nude mice. These cells showed resistance to NaB-induced apoptosis and cell cycle arrest. MEK activation led to increased expression of COX-2, Bcl-X(L), Mcl-1, and phosphorylated Bad and decreased expression of Bak. Along with elevated COX-2 levels, PGI(2) and PGE(2) levels were also increased. Pharmacologic inhibition of COX-2 inhibited MEK-induced tumor growth in vivo through enhanced apoptosis. CONCLUSIONS: COX-2 and its bioactive lipid products may play an important role in MEK-induced transformation.

Animals↗
PubMed2005

Activation of A2A adenosine receptor attenuates intestinal inflammation in animal models of inflammatory bowel disease.

BACKGROUND & AIMS: Adenosine has been implicated as an important regulator of the inflammatory response. Four subtypes of adenosine receptors (A 1 , A 2A , A 2B , and A 3 ) have been described, of which A 2A potentially inhibits inflammation. The aim of this study was to investigate the role of A 2A in mucosal inflammation by administering a selective A 2A agonist (ATL-146e) to experimental models of inflammatory bowel disease. METHODS: The anti-inflammatory effects of ATL-146e were studied in the acute and chronic rabbit formalin-immune complex models of colitis and the SAMP1/YitFc mouse model of spontaneous ileitis. RESULTS: ATL-146e significantly reduced the acute inflammatory index and tissue necrosis compared with vehicle ( P < .01) in the acute model of rabbit immune colitis. In the chronic rabbit immune colitis model, ATL-146e significantly suppressed inflammatory cell infiltration into the colonic mucosa ( P < .05) and prevented mortality. The administration of ATL-146e significantly decreased the chronic inflammatory index ( P < .01) and villus distortion index ( P < .01) in the ileum of SAMP1/YitFc mice, and ameliorated adoptively transferred ileitis in severe combined immunodeficient mice injected with CD4 + T cells from SAMP1/Yit mice ( P < .05). Tumor necrosis factor, interferon gamma, and interleukin 4 concentrations were significantly suppressed by ATL-146e treatment in supernatants from cultures of mesenteric lymph node cells of SAMP1/YitFc mice ( P < .05 vs vehicle-treated mice). CONCLUSIONS: A 2A adenosine receptor activation by ATL-146e significantly reduced inflammation in the intestinal mucosa. This effect was associated with decreased leukocyte infiltration and inhibition of proinflammatory cytokines. Activation of A 2A by selective agonism may therefore serve as a novel therapy for the treatment of inflammatory bowel disease.

Acute Disease↗
PubMed2005

Specific type IV phosphodiesterase inhibitor ameliorates thioacetamide-induced liver injury in rats.

BACKGROUND AND AIMS: Rolipram is a specific type IV phosphodiesterase inhibitor that suppresses the activity of immune cells and the production of pro-inflammatory cytokines. In this study, we assessed the effect of rolipram on acute liver injury using thioacetamide (TAA)-induced liver injury in rats as a model. METHODS: Rats were treated with rolipram (0.5-5 mg/kg, intraperitoneally) or vehicle and injected 30 min later with TAA (100 mg/kg, subcutaneously). Serum transaminase concentrations and tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta) and growth related oncogene/cytokine-induced neutrophil chemoattractant-1 (GRO/CINC-1) levels were measured and livers were examined for microscopic changes. Dose-dependent protection against TAA liver injury was based on transaminase levels and inflammatory cytokine production, and was measured 9 h after TAA when the peak release of cytokines occurred. RESULT: Rolipram suppressed liver injury based on serum aspartate transaminase (AST), alanine transaminase (ALT) and histology and reduced TNF-alpha, IL-1beta and GRO/CINC-1 levels. Rolipram, at doses of 0.5-5 mg/kg, suppressed serum transaminase and TNF-alpha production in a dose-dependent manner, and these effects were significant at doses of 2.5 and 5 mg/kg. CONCLUSION: In our rodent model of acute liver injury, rolipram clearly reduced liver damage and inhibited pro-inflammatory cytokine production. These results suggest that specific type IV phosphodiesterase inhibitors, such as rolipram, have potent hepatoprotective effects that are associated with suppressing inflammatory cytokine production.

Animals↗
PubMed2005

Selective adenosine A receptor agonist, ATL-146e, attenuates stress-induced gastric lesions in rats.

BACKGROUND: Activation of adenosine A(2A) receptors reduces the production of various pro-inflammatory cytokines and suppresses neutrophil activation. Water-immersion restraint is well known to cause gastric mucosal lesions due to stress. The pathogenesis of stress-induced gastric mucosal lesions is characterized by activation of inflammatory cells and production of inflammatory cytokines. Agonists of adenosine A(2A) receptors are known to be anti-inflammatory, but the effects of these compounds on the development of gastric mucosal lesions has not been reported. In the present study, the effect of a potent and selective adenosine A(2A) receptor agonist, ATL-146e, on water-immersion stress-induced gastric mucosal lesions was studied. METHODS: Rats were subjected to water-immersion stress with or without pretreatment with a single intraperitoneal injection of a potent and selective agonist of the adenosine A(2A) receptor. The gastric concentrations of myeloperoxidase (MPO), as an index of neutrophil accumulation, and the pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta), were measured. RESULTS: The total length of gastric erosions (ulcer index) in control rats was 21.6 +/- 3.23 mm and was reduced by 86% to 3.1 +/- 0.83 mm by pretreatment with 5.0 microg/kg ATL146e (P < 0.001). The gastric content of MPO, TNF-alpha and IL-1beta were all increased after water-immersion stress and reduced to near normal levels by ATL-146e. CONCLUSION: A specific adenosine A(2A) agonist inhibits stress-induced gastric inflammation and damage. A(2A) agonist compounds may be useful for preventing ulcers and appear to act by blocking gastric inflammation.

Adenosine A2 Receptor Agonists↗
PubMed2004

73-kDa molecular chaperone HSP73 is a direct target of antibiotic gentamicin.

Although gentamicin (GM) has been used widely as an antibiotic, the specific binding protein of the drug has not yet been understood sufficiently. Here we show that GM specifically associates with the 73-kDa molecular chaperone HSP73 and reduces its chaperone activity in vitro. In the present study, we investigated GM-specific binding proteins using a GM-affinity column and porcine kidney cytosol. After washing the column, only the 73-kDa protein was eluted from the column by the addition of 10 mm GM. None of the other proteins were found in the eluant. Upon immunoblotting, the protein was identical to HSP73. Upon CD spectrum analysis, the binding of GM to HSP73 resulted in a conformational change in the protein. Although HSP73 prevents aggregation of unfolded rhodanese in vitro, the chaperone activity of HSP73 was suppressed in the presence of GM. Using limited proteolysis of HSP73 by TPCK-trypsin, the GM binding site is a COOH-terminal for one third of the protein known to be a peptide-binding domain. During immunohistochemistry, HSP73 and GM were co-localized in enlarged lysosomes of rat kidneys with GM-induced acute tubular injury in vivo. Our results suggest that the specific association between HSP73 and GM may reduce the chaperone activity of HSP73 in vitro and/or in vivo, and this may have an interaction with GM toxicity in kidneys with GM-induced acute tubular injury.

Acetylglucosaminidase↗
PubMed2004

Expression of a 72-kDa heat shock protein, and its cytoprotective function, in gastric mucosa in cirrhotic rats.

BACKGROUND: Portal hypertensive gastropathy (PHG) is a clinical entity that is observed frequently in patients with liver cirrhosis. In PHG, gastric mucosa is highly susceptible to mucosal injury caused by noxious agents. Many studies, including ours, have reported that a 72-kDa heat shock protein (HSP72) has a crucial cytoprotective function in gastric mucosa. In this study, we investigated the expression and cytoprotective effect of HSP72 on gastric mucosa in portal hypertensive rats. METHODS: PHG was produced by bile duct ligation (BDL) or carbon tetrachloride administration in male Sprague-Dawley rats. The expression of HSP72 in the gastric mucosa was evaluated by Western blotting. Induction of gastric mucosal HSP72 by 6-h water-immersion stress was compared between cirrhotic and control rats. Also, mucosal protective abilities against hydrochloric acid (HCl; 0.6 N) following pretreatment with water-immersion stress to induce HSP72 were studied in both groups. RESULTS: Portal venous pressure was significantly higher in cirrhotic rats compared with control rats ( P < 0.05). Baseline expression (before water-immersion stress) of mucosal HSP72 was significantly lower in cirrhotic rats compared with control rats. HCl-induced gastric mucosal lesions were significantly suppressed in control rats compared with cirrhotic rats, especially when HSP72 was preinduced by water-immersion stress. CONCLUSIONS: These findings suggest that HSP72 in the gastric mucosa plays a crucial role with respect to cytoprotection; the induction of HSP72 may provide therapeutic strategies for protection against mucosal injury in PHG.

Animals↗
PubMed2004

Mechanical stretch induces matrix metalloproteinase 1 production in human hepatic stellate cells.

In increasing portal blood flow, hepatic stellate cells (HSC) may be lengthened in response to mechanical stretch stimulation and their function may be changed. However, little is known about the influence of mechanical stretch on hepatic stellate cells. We examined production of matrix metalloproteinases (MMP), tissue inhibitors of metalloproteinases (TIMP), and extracellular matrix by hepatic stellate cells to investigate the relationship between mechanical stretch and hepatic fibrosis. LI90 cells, human hepatic stellate cells, were stretched cyclically using the Flexer cell strain unit. Concentrations of MMP1, MMP2, TIMP1, TIMP2, type I collagen C-telopeptide (1CTP), procollagen III propeptide (PIIIP), and hyaluronic acid in culture supernatants were determined. MMP1, MMP2, and TIMP1 mRNA expression was measured by reverse transcription-polymerase chain reaction (RT-PCR). In stretched LI90 cells, concentration of MMP1 showed an increase relative to unstretched cells, but concentrations of MMP2, TIMPl, and TIMP2 showed a decrease. MMP1/TIMP1 ratio and MMP1 mRNA expression showed an increase in stretched cells. Our finding suggested that in the early phase of portal hypertension, hepatic stellate cells increase production of MMPl and decrease production of TIMP1 and TIMP2, activated by mechanical stretch.

Journal Article↗
PubMed2004

Induction of a 72-kDa heat shock protein and protection against lipopolysaccharide-induced liver injury in cirrhotic rats.

BACKGROUND AND AIM: A 70-kDa heat shock protein (stress-inducible HSP70, HSP72) has been reported to be a cytoprotectant in a variety of organs. It has been reported that HSP72 protected non-cirrhotic rats against endotoxemia. However, its cytoprotective effect against endotoxemia in cirrhotic rats has not yet been studied. In this study, we investigated the cytoprotective effect of HSP72 on lipopolysaccharide (LPS)-induced liver injury in carbon tetrachloride (CCl(4))-induced cirrhotic rats. METHODS: Liver cirrhosis was produced by an 8-week intraperitoneal injection of CCl(4) in male Sprague-Dawley rats. Expression of HSP72 was investigated using western blot analysis. Cirrhotic rats were given an intraperitoneal injection of LPS (10 mg/kg) with or without hyperthermia (42.5 degrees C, 15 min) preconditioning. Liver injury was assessed biochemically (aspartate transaminase, alanine transaminase, bilirubin, lactate dehydrogenase, creatinine) and histologically. The plasma tumor necrosis factor (TNF)-alpha level was determined. RESULTS: Hyperthermia preconditioning induced a 4-fold increase in HSP72 in the cirrhotic rat liver. Pre-induction of HSP72 prevented LPS-induced liver injury, as evaluated using serum biochemical parameters and histology with reduced TNF-alpha response. CONCLUSION: These findings suggest that pre-induction of HSP72 may provide therapeutic strategies for Gram-negative sepsis-induced liver injury in liver cirrhosis.

Animals↗
PubMed2004

[Rolipram, a specific type IV phosphodiesterase inhibitor, ameliorates indomethacin-induced gastric mucosal injury in rats].

Inhibition of type IV phosphodiesterase activity is beneficial in various inflammation mediated by its function to suppress the production of inflammatory cytokines in inflammatory cells. Nonsteroidal anti-inflammatory drugs(NSAIDs) such as indomethacin are well known to develop gastric mucosal lesion. As pathogenesis of indomethacin induced gastric mucosal lesion, activation of neutrophils and inflammatory cytokine production play critical roles. However, the effect of phosphodiesterase inhibitors on development of gastric mucosal lesion has not been reported. In the present study, we examined the effect of specific type IV phosphodiesterase inhibitor(rolipram) on NSAIDs-induced gastric mucosal lesion. Also, we examined the effect of rolipram on tissue prostaglandin E2 production.

Animals↗
PubMed2003

Rolipram, a specific type IV phosphodiesterase inhibitor, ameliorates indomethacin-induced gastric mucosal injury in rats.

Inhibition of type IV phosphodiesterase activity is beneficial in various inflammation mediated by its function to suppress the production of inflammatory cytokines in inflammatory cells. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as indomethacin are well known to develop gastric mucosal lesion. As pathogenesis of indomethacin induced gastric mucosal lesion, activation of neutrophils and inflammatory cytokine production play critical roles. However, the effect of phosphodiesterase inhibitors on development of gastric mucosal lesion has not been reported. In the present study, we examined the effect of specific type IV phosphodiesterase inhibitor (rolipram) on NSAIDs-induced gastric mucosal lesion. Also, we examined the effect of rolipram on tissue prostaglandin E2 (PGE2) production. Indomethacin-induced gastric mucosal injury was produced by the intragastric administration of indomethacin (30 mg/kg). Rolipram was injected to the rats intraperitoneally 30 min before the indomethacin administration. Ulcer index and tissue myeloperoxidase (MPO) activity of the gastric mucosa was evaluated. The gastric concentration of PGE2 was determined by RIA. Gastric mucosal lesion induced by indomethacin was significantly inhibited with treatment of rolipram. Mucosal MPO activity was also suppressed by administration of rolipram. Gastric mucosal PGE2 concentration was not affected by intraperitoneal injection of rolipram. Based on these data, the beneficial effects of rolipram on indomethacin-induced gastric mucosal injury may be attributed to its anti-inflammatory properties.

Journal Article↗
PubMed2002

Induction of a 72-kDa heat-shock protein in cultured rat gastric mucosal cells and rat gastric mucosa by zinc L-carnosine.

An antiulcer drug, zinc L-carnosine (polaprezinc), provides gastric mucosal protection against various irritants. In this study, we evaluated the effects of zinc L-carnosine on expression of 72-kDa heat shock protein (HSP72, stress inducible HSP70), which is known as an endogenous cytoprotectant in a wide variety of cells, including rat gastric mucosa in vitro and in vivo. Expression of HSP72 after exposure to zinc L-carnosine, zinc sulfate, or L-carnosine (1-300 microM) in rat gastric mucosal cells (RGM1) and intragastric administration of zinc L-carnosine, zinc sulfate (30 or 100 mg/kg) and L-carnosine (76 mg/kg) was investigated by western blotting and densitometric analysis. Exposure to zinc L-carnosine and zinc sulfate increased the expression of HSP72 significantly in RGM1 cells. Intragastric administration of zinc L-carnosine and zinc sulfate showed significant increment in HSP72 in rat gastric mucosa also in vivo. The ability to induce HSP72 is significantly higher in zinc L-carnosine compared with zinc sulfate based on molecular concentration in vivo. However, L-carnosine did not increase the expression of HSP72 in vitro and in vivo. Zinc derivatives, especially zinc L-carnosine, could be a strong HSP72 (chaperon) inducer, which has been known to enhance mucosal protective ability.

Animals↗
PubMed2002

Characterization of the 105-kDa molecular chaperone. Identification, biochemical properties, and localization.

We have characterized the biochemical properties of the testis and brain-specific 105-kDa protein which is cross-reacted with an anti-bovine HSP90 antibody. The protein was induced in germ cells by heat stress, resulting in a protein which is one of the heat shock proteins [Kumagai, J., Fukuda, J., Kodama, H., Murata, M., Kawamura, K., Itoh, H. & Tanaka, T. (2000) Eur. J. Biochem.267, 3073-3078]. In the present study, we characterized the biochemical properties of the protein. The 105-kDa protein inhibited the aggregation of citrate synthase as a molecular chaperone in vitro. ATP/MgCl2 has a slight influence of the suppression of the citrate synthase aggregation by the 105-kDa protein. The protein possessed chaperone activity. The protein was able to bind to ATP-Sepharose like the other molecular chaperone HSP70. A partial amino-acid sequence (24 amino-acid residues) of the protein was determined and coincided with those of the mouse testis- and brain-specific APG-1 and osmotic stress protein 94 (OSP94). The 105-kDa protein was detected only in the medulla of the rat kidney sections similar to OSP94 upon immunoblotting. The purified 105-kDa protein was cross-reacted with an antibody against APG-1. These results suggested that APG-1 and OSP94 are both identical to the 105-kDa protein. There were highly homologous regions between the 105-kDa protein/APG-1/OSP94 and HSP90. The region of HSP90 was also an immunoreactive site. An anti-bovine HSP90 antibody may cross-react with the 105-kDa protein similar to HSP90 in the rat testis and brain. We have investigated the localization and developmental induction of the protein in the rat brain. In the immunohistochemical analysis, the protein was mainly detected in the cytoplasm of the nerve and glial cells of the rat brain. Although the 105-kDa protein was localized in all rat brain segments, the expression pattern was fast in the cerebral cortex and hippocampus and slow in the cerebellum.

Adenosine Triphosphate↗
PubMed2002

Mammalian HSP60 is quickly sorted into the mitochondria under conditions of dehydration.

There are few reports concerning the sorting mechanisms of mammalian HSP60 into the mitochondria from the cytoplasm. In the present study we investigated the protein import system. Based on immunoblotting and immuno-histochemistry, HSP60 was detected in both the cytoplasm and mitochondria. The purified cytoplasmic HSP60 showed chaperone activity, and the protein was imported into the mitochondria in vitro by a mitochondrial import assay. HSP60 mRNA was increased in the kidney papilla of rats that had been water restricted for three and five days, but no changes in HSP60 mRNA were detected in the cortex or the medulla of the rat kidneys. Upon immunoblotting, HSP60 was detected in both the cytoplasm and the mitochondria of normal rat kidney cortex, medulla, and papilla in almost the same quantity. HSP60 was remarkably decreased in the kidney papilla of rats that were water restricted but the protein was increased in the mitochondria of the rat kidney papilla. We also analysed binding of the protein to the signal sequence of HSP60 using signal sequence-affinity column chromatography. We identified only one protein band with a molecular mass of 70 kDa on SDS/PAGE. The protein was eluted from the affinity column by an excess of signal peptide or by 5 mm ATP. Upon immunoblotting, the 70-kDa protein cross-reacted with an antibody against HSP70. These results suggested that mammalian HSP60 is located both in the cytoplasm as a stable cytoplasmic HSP60 and also in the mitochondria under normal conditions. The cytoplasmic HSP60 is quickly imported into the mitochondria under severe conditions by cytoplasmic HSP70.

Amino Acid Sequence↗