Biomedical subjects

T Ikeno

Publications and source records attributed to T Ikeno.

At least 19 recordsLinked to original sources

PubMed2003

Duodenogastric reflux and Helicobacter pylori infection synergistically increase gastric mucosal cell proliferative activity in Mongolian gerbils.

BACKGROUND: Helicobacter pylori and duodenogastric reflux (DGR) are both recognized as aetiological factors in chronic gastritis and gastric carcinogenesis. In this study, a Mongolian gerbil (MG) model was used to investigate the histopathological changes in the gastric mucosa resulting from DGR and/or H. pylori infection. METHODS: One-hundred-and-eleven 7-week-old, specific-pathogen-free, male MGs were divided into four groups: normal controls, gerbils with surgically induced DGR, and H. pylori-infected gerbils with and without DGR. Gerbils were killed 4, 12 and 26 weeks after DGR surgery, their stomachs removed and sections prepared. Sections were fixed immediately in 20% phosphate-buffered formalin and subjected to haematoxylin and eosin staining, Alcian blue at pH 2.5/periodic acid-Schiff staining, and immunostaining for smooth muscle cells, H. pylori and 5'-bromo-2'-deoxyuridine (BrdU). RESULTS: The gastric mucosa of H. pylori-infected gerbils showed chronic active gastritis irrespective of DGR throughout the experimental period. The gastric mucosa of H. pylori-infected gerbils with DGR demonstrated higher BrdU labelling than in the other groups. CONCLUSIONS: In MGs, DGR and H. pylori infection synergistically increased gastric mucosal cell proliferative activity. DGR and H. pylori infection may be involved synergistically in gastric carcinogenesis by increasing cell proliferative activity.

Animals↗

PubMed2001

Highly chemo-, diastereo-, and enantioselective reduction of 1,2-dialkyl-3-aryl-1,3-diketones for preparation of aldol-type compounds.

[reaction: see text]. Highly chemo-, diastereo-, and enantioselective borohydride reduction of 2-substituted-1,3-diketones was achieved in the presence of the optically active beta-ketoiminato cobalt complex catalysts to afford the optically active 2-substituted-3-hydroxyketones. The present catalytic and enantioselective reduction could provide an alternative potential for preparation of optically active anti-aldol-type compounds.

Journal Article↗

PubMed2001

Reductive desymmetrization of 2-alkyl-1,3-diketones catalyzed by optically active beta-ketoiminato cobalt complexes.

[reaction: see text] The reductive desymmetrization of acyclic 1,3-diketones was achieved for the first time by catalytic borohydride reduction in the presence of optically active beta-ketoiminato cobalt(II) complex catalysts. In this reaction, various 2-substituted-1,3-diaryl-1,3-propanediones were converted into the corresponding optically active 2-substituted-1,3-diaryl-3-hydroxypropanone in good-to-high yields with excellent diastereo- and enantioselectivities and high catalytic efficiencies.

Journal Article↗

PubMed2001

Optically active beta-ketoiminato cationic cobalt(III) complexes: efficient catalysts for enantioselective carbonyl-ene reaction of glyoxal derivatives.

[see reaction]. Optically active beta-ketoiminato cationic cobalt(III) complexes were synthesized as effective Lewis acid catalysts for the enantioselective carbonyl-ene reaction. In the presence of a catalytic amount of cobalt(III) hexafluoroantimonate derived from the optically active 1,2-diphenyl-1,2-ethanediamine, the carbonyl-ene reaction with a variety of alkenes and glyoxal derivatives smoothly proceeded to afford the corresponding homoallylic alcohols in good-to-high yields with high enantioselectivities.

Journal Article↗

PubMed2001

Molecular design of a new class of spin-labeled ribonucleosides with N-tert-butylaminoxyl radicals.

We designed a new type of spin-labeled nucleosides with an N-tert-butylaminoxyl radical which is introduced to the nucleobase directly. Purine and pyrimidine ribonucleosides containing the aminoxyl radical such as 1a-d, 2, 3, and 4 were synthesized to investigate the stability and behavior of the N-tert-butylaminoxyl radical on a nucleobase. Lithiation of tri-O-silylated 6-chloropurine ribonucleoside (5) followed by reaction with 2-methyl-2-nitrosopropane (MNP) gave the key compound 6a, which was further converted to 6b-d. Oxidation of the obtained 6a-d and their triols (7a-d) with Ag(2)O led to formation of the corresponding stable spin-labeled nucleosides (8a-d and 1a-d), which were confirmed by EPR spectroscopy. Similarly, the precursors of spin-labeled pyrimidines (13, 20, and 23) were synthesized by site-selective lithiation of tri-O-protected pyrimidine derivatives (9, 18, and 21) followed by the reaction with MNP and deprotection. An EPR study showed that the aminoxyl radicals (2, 3, and 4) were stable and that their hyperfine structures were dependent on the position of the radical. Electron densities of pyrimidine also affected hyperfine structures.

Butylamines↗

PubMed2001

Paradoxical role of Helicobacter pylori infection: protective effect against ethanol-induced gastric mucosal injury in Mongolian gerbils.

We investigated the effect of ethanol (a representative necrotizing agent) on gastritis induced by Helicobacter pylori infection in Mongolian gerbils. Seventy-eight gerbils were used. Four and 12 weeks after H. pylori inoculation, 30% ethanol was administered into the stomach. The stomachs were removed after 30 min, the intramucosal prostaglandin (PG) E2 concentration was measured, and histopathology was recorded. H. pylori infection caused chronic active gastritis, gastric erosion, hypersecretion of mucin from gland mucus cells, and a rise in the activity of intramucosal PGE2. After ethanol administration, gastric erosion was significantly less in animals infected with H. pylori than in uninfected animals. In conclusion, in the early stage of H. pylori infection, accentuation of intramucosal PGE2 and hypersecretion of mucin from gland mucus cells have a protective effect against gastric mucosal injury induced by necrotizing agents.

Animals↗

PubMed2001

Synthesis and properties of a new class of nucleosides with spin source.

Novel spin-labeled ribonucleosides 1-5 were synthesized to investigate stability and behavior of N-tert-butyl aminoxyl radical on nucleobase. Site selective lithiation of tri-O-protected ribonucleosides followed by the reaction with 2-methyl-2-nitrosopropane (MNP) resulted in introduction of N-tert-butylhydroxylamino group into various positions of purine or pyrimidine nucleus. Oxidation of the obtained hydroxylamines with Ag2O led to formation of 1-5. EPR study showed that the unpaired electron of the aminoxyl radical was delocalized into the nucleobase and hyperfine structures were dependent on the position of the radical.

Electron Spin Resonance Spectroscopy↗

PubMed2001

Serum immunoglobulin G immune response to Helicobacter pylori antigens in Mongolian gerbils.

The Mongolian gerbil model for Helicobacter pylori infection is an animal model that mimics human disease. We examined the serum immune response to H. pylori infection in gerbils by enzyme-linked immunosorbent assay (ELISA) and Western blotting, both with whole-cell (H. pylori) extracts. A total of 66 7-week-old specific-pathogen-free male gerbils were inoculated orogastrically with H. pylori strain ATCC 43504. Sera were collected 1, 2, 4, 8, 12, 26, 38, and 52 weeks after H. pylori inoculation. Sixty-nine noninfected gerbils and their sera were used as controls. The specificity of the ELISA was 95.7%. The frequency of seropositivity increased over time: 2 of 10 (20%), 7 of 10 (70%), and 7 of 7 (100%) samples of sera from inoculated gerbils were positive for H. pylori at 2, 4, and 8 weeks postinoculation, respectively. Western blot assays showed that the primary immunoglobulin G (IgG) response against low-molecular-mass (25-, 30-, and 20-kDa) proteins appeared after a lag period of 2 to 8 weeks after inoculation. Antibodies against 160-, 150-, 110-, 120-, 80-, 66-, and 63-kDa proteins were observed 12 weeks after inoculation. The early reactive 30-kDa protein was identified as a urease alpha subunit by N-terminal amino acid sequencing. After 26 weeks, two groups of animals could be distinguished: one group developed ulcers (n = 5), and the other developed hyperplastic polyps without ulcers (n = 19). Gerbils in the gastric ulcer group showed significantly higher serum anti-H. pylori IgG levels than did gerbils in the hyperplastic group (P = 0.001) as measured by ELISA. Furthermore, a higher proportion of animals developed antibodies to H. pylori proteins of 26, 25, and 20 kDa in the ulcer group than those animals with hyperplastic polyps (75 to 100% versus 17 to 50%) in Western blot assays. These results highlight the importance of the immune response of the host in the development of H. pylori-related gastric lesions.

Animals↗

PubMed2000

Timing of N-methyl-N-nitrosourea administration affects gastric carcinogenesis in Mongolian gerbils infected with Helicobacter pylori.

In Mongolian gerbils, the gastric mucosa shows dramatic changes after Helicobacter pylori inoculation. The influence of the timing of N-methyl-N-nitrosourea (MNU) administration after H. pylori inoculation on gastric carcinogenesis was investigated. Ninety-two gerbils were divided into four groups. One group was given MNU at 24 weeks, and another at 1 week, after H. pylori inoculation. The other groups received only MNU. Stomachs were excised for histological examination 20 weeks after completing the MNU treatment. Carcinomas arose only in animals given MNU 1 week after H. pylori inoculation. In the relationship between H. pylori and gastric carcinogenesis, H. pylori is a promoter rather than an initiator, and other environmental factors (the timing of MNU administration) play important roles.

Adenocarcinoma↗

PubMed2000

CD8-depleted donor leukocyte transfusions for cytomegalovirus antigenemia in patient with acute lymphoblastic leukemia treated with allogeneic CD34(+) cell transplantation.

A 24-year-old man with acute lymphoblastic leukemia received an allogeneic CD34(+) cell transplant from an HLA-mismatched sibling because of refractory disease. The CD34(+) cells were enriched by the immunomagnetic method. One month after the transplant his situation became complicated due to cytomegalovirus (CMV) antigenemia, which was resistant to treatment with ganciclovir. He was treated with CD8(+) cell-depleted donor lymphocyte transfusions (CD8-depleted DLT). After CD8-depleted DLT, the CMV antigenemia disappeared completely. This case report suggested that CD8-depleted DLT was an effective therapy for CMV antigenemia after allogeneic CD34(+) cell transplantation.

Adult↗

PubMed2000

Revascularization using the short gastric vessels of the gastric tube after subtotal esophagectomy for intrathoracic esophageal carcinoma.

BACKGROUND: Maintaining sufficient blood flow to the substitutive organ after esophagectomy is essential to decrease the risk of anastomotic leakage. STUDY DESIGN: Forty-one patients underwent subtotal esophagectomy for intrathoracic esophageal carcinoma and reconstruction using the gastric tube. Additional vascular anastomosis between the short gastric vessels and the vessels in the neck was performed in 15 patients. Tissue blood flow was measured by laser Doppler flowmetry before and after vascular anastomosis. The incidence of anastomotic leakage in the revascularization group was compared with that in the remaining 26 patients. RESULTS: Venous anastomosis was performed in 14 patients and arterial anastomosis in 9. There was a significant increase in tissue blood flow after venous anastomosis alone (mean percent increase: 36%; p < 0.01), and after arterial and venous anastomoses (mean percent increase: 108%; p < 0.01). No anastomotic leakage was observed in the revascularization group; six patients (23.1%) in the control group had leakage (p < 0.05). Patients in the revascularization group started taking a meal 10.0 +/- 0.4 days postoperatively, compared with 15.1 +/- 1.8 days in the control group (p < 0.05). CONCLUSIONS: Additional vascular anastomosis in esophageal reconstruction after subtotal esophagectomy achieved good results. This procedure can reduce the risk of anastomotic leakage and may be useful for esophageal reconstruction.

Aged↗

PubMed1999

Use of the Harmonic Scalpel in open abdominoperineal surgery for rectal carcinoma.

We describe a technique of open abdominoperineal resection with the use of the Harmonic Scalpel in seven patients. Using this instrument we dissected all pelvic vessels, including the middle hemorrhoidal artery, with no subsequent bleeding. In addition, we divided the levator ani muscles completely in the abdominal procedure alone.

Abdomen↗

PubMed1999

Technetium-99m-tetrofosmin imaging of lung cancer: relationship with histopathology.

Tc-99m-tetrofosmin is an agent to delineate cancer. To elucidate the usefulness of Tc-99m-tetrofosmin scintigraphy, we analyzed the relationship between the uptake of Tc-99m-tetrofosmin and histopathology in patients with lung cancer. SPECT studies were conducted twice: 15 minutes (early scan), and 60 minutes (delayed scan), after intravenous injection of 740 MBq Tc-99m-tetrofosmin. We calculated the retention index in order to evaluate the degree of Tc-99m-tetrofosmin retention in the primary tumor. The retention indices were significantly lower in squamous cell carcinoma than those of small cell carcinoma or adenocarcinoma. As the retention indices of Tc-99m-tetrofosmin were different in each histopathology, the index might play a part as a tumor marker of lung cancer.

Adenocarcinoma↗

PubMed1999

Helicobacter pylori-induced chronic active gastritis, intestinal metaplasia, and gastric ulcer in Mongolian gerbils.

The establishment of persisting Helicobacter pylori infection in laboratory animals has been difficult, but in 1996 Hirayama reported the development of a successful Mongolian gerbil model. The present study was undertaken with two aims: to better characterize the normal histological structure and histochemical properties of the gastric mucosa of the Mongolian gerbil; and to evaluate the progression of the histopathological features of H. pylori-induced gastritis in this animal model for one year after the experimental infection. Seventy-five Mongolian gerbils were used. Mongolian gerbils were sacrificed at 2, 4, 8, 12, 26, 38, and 52 weeks after H. pylori inoculation. Sections prepared from stomachs immediately fixed in Carnoy's solution were stained with hematoxylin and eosin and Alcian blue at pH 2.5/periodic acid-Schiff, a dual staining consisting of the galactose oxidase-cold thionin Schiff reaction and paradoxical Concanavalin A staining, and with immunostaining for H. pylori and BrdU. H. pylori infection induced in the Mongolian gerbil a chronic active gastritis, in which a marked mucosal infiltration of neutrophils on a background of chronic inflammation became detectable 4 weeks after inoculation and continued up to 52 weeks. Intestinal metaplasia and gastric ulcers appeared after 26 weeks in some of the animals, whereas others developed multiple hyperplastic polyps. The Mongolian gerbil represents a novel and useful model for the study of H. pylori-induced chronic active gastritis and may lend itself to the investigation of the epithelial alterations that lead to intestinal metaplasia and gastric neoplasia.

Animals↗

PubMed1999

Additional microvascular anastomosis in reconstruction after total esophagectomy for cervical esophageal carcinoma.

BACKGROUND: Maintaining sufficient blood flow to the substitute organ after total esophagectomy is essential for decreasing the risk of anastomotic leakage. Additional venous, or arterial and venous, anastomoses between the vessels of the gastric tube and the vessels in the neck after total esophagectomy are described for 11 patients with cervical esophageal carcinoma. METHODS: The tissue blood flow was measured by laser Doppler flowmetry before and after anastomosis. Venous anastomosis was performed for all 11 patients, and arterial anastomosis was added for 7 patients. RESULTS: A significant increase in tissue blood flow was observed after venous anastomosis alone (mean, 19%; P < 0.05) and after arterial and venous anastomoses (mean 43%; P < 0.01). There was no anastomotic leakage or hospital death. CONCLUSIONS: This procedure may reduce the risk of anastomotic leakage especially in the case of pharyngogastrostomy following total esophagectomy.

Anastomosis, Surgical↗

PubMed1999

[Primary pleural non-Hodgkin's lymphoma without chronic pyothorax].

Most cases of primary pleural malignant lymphoma develop following chronic pyothorax. We report a case of primary pleural non-Hodgkin's lymphoma without chronic pyothorax. A 63-year-old woman was referred and admitted to our hospital with a right pleural effusion that was detected during a routine physical checkup. Her liver, spleen, and superficial lymph nodes were not palpable on physical examination. The massive right pleural effusion and a pleural mass were demonstrated on chest X-ray films and thoracic computed tomograms. Diffuse large B-cell non-Hodgkin's lymphoma was diagnosed by needle biopsy from the pleura, and the clinical stage was IE. Pleural effusion specimens contained no identifiable lymphoma cells, and examinations for Mycobacterium species were also negative. Human herpes virus 8 (HIV-8) DNA was detected in lymphocytes from the peripheral blood and pleural effusion. Epstein-Barr virus-encoded small RNAs and HHV-8 DNA were both negative in biopsied tissue from the pleural mass. Although a complete remission was achieved, the lymphoma relapsed about 8 months later. The patient is currently receiving salvage chemotherapy. Cases of primary pleural non-Hodgkin's lymphoma with massive pleural effusion that are not preceded by chronic pyothorax or Kaposi's sarcoma are very rare.

Chronic Disease↗

PubMed1998

Helicobacter pylori infection enhances N-methyl-N-nitrosourea-induced stomach carcinogenesis in the Mongolian gerbil.

No previous report has demonstrated the relationship between Helicobacter pylori (HP) infection and gastric carcinogenesis in an experimental animal model. A total of 170 male Mongolian gerbils (MGs) were divided into nine groups (18 < or = n < or = 20 for each group). MGs of four groups were inoculated with HP before or after continuous N-methyl-N-nitrosourea (MNU) administration via the drinking water. Both intestinal-type and diffuse-type adenocarcinomas, including signet ring-cell carcinomas, were found at 40 weeks after the study commenced, but only in the HP inoculation groups with MNU exposure and not in the MNU alone or HP inoculation alone control groups. The present findings demonstrate that HP infection increases the incidence of MNU-induced adenocarcinoma of the glandular stomach in MGs.

Adenocarcinoma↗

PubMed1998

Induction of glandular stomach cancers in Helicobacter pylori-sensitive Mongolian gerbils treated with N-methyl-N-nitrosourea and N-methyl-N'-nitro-N-nitrosoguanidine in drinking water.

An animal model of stomach carcinogenesis was established using Mongolian gerbils with N-methyl-N-nitrosourea (MNU) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) as the carcinogens. In addition, the sensitivity of these gerbils to Helicobacter pylori (H. pylori) was confirmed. One hundred and sixty specific pathogen-free male MGS/Sea animals, 7 weeks old, were treated with MNU in the drinking water (30 ppm for alternate weeks to give 10 weeks exposure, or 10 ppm or 3 ppm for 20 weeks continuous exposure), or given MNNG in the drinking water at 400 ppm or 200 ppm for 20 weeks, or orally inoculated with ATCC43504 H. pylori (1.7 x 10(8) CFUs/animal). Adenocarcinomas in the glandular stomach were found in 2 out of 12 effective animals (2/ 12) treated with 30 ppm MNU at week 20, although all were dead or moribund by week 30 due to MNU toxicity. At week 50, the incidences of gastric adenocarcinomas in groups treated with 10 ppm MNU, 3 ppm MNU, 400 ppm MNNG, and 200 ppm MNNG were 2/21 (9.5%), 1/23 (4.3%), 7/ 11 (63.6%), and 1/10 (10.0%). The lesions were generally well differentiated, although poorly differentiated adenocarcinoma was also found in a single gerbil in each of the 10 ppm MNU and 400 ppm MNNG groups. In control animals no tumors were found. In the infection study, the animals were killed at week 20, and H. pylori was detected in all cases, causing multiple erosions with marked inflammatory cell infiltration in the lamina propria and submucosa, and frequent formation of lymphoid follicles. Thus, MNU and MNNG in the drinking water induced neoplastic lesions in the glandular stomach epithelium of H. pylori-sensitive gerbils.

Adenocarcinoma↗