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Biomedical subjects

K Aoki

Publications and source records attributed to K Aoki.

At least 343 records · Page 19Linked to original sources
PubMed1997

[Concealed infective endocarditis].

The occurrence of concealed infection or "natural remission" in infective endocarditis was investigated microscopically in 35 consecutive patients (36 valves) with infective endocarditis (between April 1987 and May 1995). Four patients were considered as having concealed or silent infective endocarditis. Preoperative diagnosis of these patients was mitral valve prolapse, rheumatic aortic valve stenosis with insufficiency, aortic valve prolapse and hypertrophic cardiomyopathy, respectively. These patients did not present with any clinical signs of infective endocarditis such as cardiac murmur and ventricular dysfunction. Histological examination of the excised valves revealed valvular perforation, small round cell infiltration, neovascularization, remnants of vascular smooth muscle cells, and organizing vegetations. These findings are consistent with the histological findings of infective endocarditis. Latent infective endocarditis may be present without inflammatory manifestation.

Aortic Valve Insufficiency↗
PubMed1997

[Lung cancer with a sarcoid-like reaction in the primary tumor].

An 80-year-old woman was admitted to the hospital because of a nodular lesion in the right upper lobe of the lung. Transbronchial biopsy was performed and adenocarcinoma of the lung was confirmed by pathological examination. The tumor was resected by right upper lobectomy and was found to be a moderately differentiated tubular adenocarcinoma. Numerous non-caseating epithelioid cell granulomas were also found intermingled with the cancer cells. Metastasis was apparent in several regional lymph nodes but no granulomatous lesions were found in any lymph node, regardless of metastasis. These findings were compatible with a "sarcoid-like reaction" because there was no clinical evidence of generalized sarcoidosis or pulmonary mycobacterial infection. Although sarcoid-like reactions are occasionally associated with cancer, formation of an epithelioid cell granuloma inside the primary tumor is very rare. All the reported cases of a sarcoid-like reaction within the primary lung tumor so far were with adenocarcinoma. The sarcoid-like reaction may be a local immune response to the cancer cells.

Adenocarcinoma↗
PubMed1997

[Mantle cell lymphoma with multiple extranodal involvement].

A 79-year-old male was admitted to our hospital because of general fatigue and night sweat. Physical examination showed generalized superficial lymphadenopathy, marked splenomegaly, and tumors in the conjunctiva and the abdomen. Chest X-ray and computed tomography (CT) revealed pleural effusion and intrathoracic lymphadenopathy. Abdominal ultrasonography and CT showed hepatosplenomegaly and intraperitoneal tumors. Upper gastrointestinal fiberscopy revealed multiple polypoid lesions and ulcers in the duodenum and the stomach. Involvement of relatively small-sized lymphocytes with cleaved nuclei was identified in each biopsied specimen from a cervical lymph node, a tumor in the conjunctiva, gastrointestinal polypoid lesions, and the bone marrow. Surface marker analysis of abnormal lymphocytes in the bone marrow revealed that CD5, CD19, and CD20 were strongly positive, but CD23 was weakly positive. Although (11:14)(q13:q32) translocation was not identified by chromosome analysis of bone marrow cells, Northern blot analysis of bone marrow cells revealed overexpression of the PRAD1 oncogene. Diagnosis of mantle cell lymphoma (MCL) was made. Combination chemotherapy by cyclophosphamide and vincristine was not effective, but etoposide perorally given at a dose of 50 mg per day was effective. In MCL, extranodal involvement of a digestive tract and bone marrow is well known. This case suggests that involvement of multiple organs including lacrimal glands and pleura could be characteristic of MCL cells.

Abdominal Neoplasms↗
PubMed1997

[Mitral valve re-replacement in patients aged 70 years and older: is age alone not operative risk factor?].

We analyzed the risk of mitral valve re-replacement (re-MVR) in patients over 70-year-old. Surgical and late follow-up results were compared between 14 elderly patients over 70-year-old (group I) and 23 patients aged from 60 to 69-year-old (group II) who underwent re-MVR due to primary tissue failure (PTF). Donation of autologous blood and a rate of replaced valve prosthesis (mechanical/biological) were different between the two groups. There were no differences in the other factors such as clinical profile, preoperative organ function, operative characteristics, post operative relating factors. No operative death occurred in both groups. There was one hospital death in group I (a hospital mortality rate of 7.1%). The cause of death was related to massive cerebral infarction due to anticoagulant-related thromboembolic event. 4-64 months after re-MVR, the improvement of a NYHA function class was I-II in the two groups. With improvement in myocardial protection and intraoperative strategies, the operative risk in patients undergoing re-MVR over 70-year-old has been markedly reduced. Surgical results in aged patients were satisfactory and age alone is not a contraindication for this operation. The re-MVR in aged patients should be done at the early stage of PTF before progress of cardiac failure.

Age Factors↗
PubMed1997

[Clinical results of single-stage mobilization of pectoral muscle flaps and omental transposition for infected mediastinitis after open heart surgery].

The purpose of this study was to retrospectively evaluate the outcome of refractory infected mediastinitis managed primarily with mobilization of pectoral muscle flaps and omental transposition. From January 1992 to December 1995, infected mediastinitis occurred in 11 (2.5%) of 447 consecutive patients. All patients required sternal debridement. The wound was thoroughly irrigated with a solution of 0.5% povidone-iodine in physiological saline after debridement and then the defect was repaired. Reconstruction of the chest wall was attained using pectoral muscle flaps in seven patients and pectoral muscle flaps and omental transposition in four. Antibiotic therapy was provided for 6 weeks or more according to the regimen in North America. No hospital deaths occurred after surgery. Significant early complications occurred in four patients. The reasons for the prolonged hospitalization were a recurrent wound infection, prosthetic valve endocarditis and saphenous vein graft pseudoaneurysm formation caused by Methicillin-resistant Staphylococcus aureus (MRSA) and Methicillin-resistant Staphylococcus epidermidis (MRSE). Length of stay in ICU after surgical treatment was range 1 to 140 days (an average of 11 +/- 3 days in 9 patients without complications in ICU). Duration between surgical treatment and discharge was range 47 to 300 days (an average of 58 +/- 8 days in 7 patients without significant early complications). At the time of this report, the patients are doing well with no signs of recurrence of infection. The mean follow-up was 28.8 months (range 8 to 48 months). We conclude that single-stage mobilization of pectoral muscle flaps together with omental transposition is very usefull for managing refractory infected mediastinitis. But careful follow-up is needed after this procedure in case of MRSA-caused mediastinitis because of its tendency to recur.

Adult↗
PubMed1997

Suppression of Ki-ras p21 levels leading to growth inhibition of pancreatic cancer cell lines with Ki-ras mutation but not those without Ki-ras mutation.

Ki-ras point mutation characteristically occurs frequently in human pancreatic cancer. To clarify the effect of antisense Ki-ras RNA on various pancreatic cancer cell lines, a plasmid expressing an antisense Ki-ras gene fragment (AS-K-ras-LNSX) was transduced into seven human pancreatic cancer cell lines (AsPC-1, MIA PaCa-2, PANC-1, PSN-1, BxPC-3, Hs 700T, and Hs 766T) by liposome-mediated transfection. Western blot analysis showed that transfection of AS-K-ras-LNSX led to a significant reduction in the amounts of Ki-ras p21 protein in all the pancreatic cancer cell lines except BxPC-3. The growth of pancreatic cancer cell lines having Ki-ras point mutations (AsPC-1, MIA PaCa-2, PANC-1, and PSN-1) was suppressed after transduction of AS-K-ras-LNSX, whereas the effect of the antisense construct on the growth was not significant in cell lines with a wild-type Ki-ras gene (BxPC-3, Hs 700T, and Hs 766T). These results suggest that the pancreatic cancer cells with activated Ki-ras depend heavily on a Ki-ras p21-mediated growth signal pathway for their growth because they were far more susceptible to the suppression of the Ki-ras p21 protein than the cells with wild-type Ki-ras. The remarkably increased dependence of the cancer-cell growth circuitry on one or a few crucial regulatory molecules may thus be a common feature of the cancer cells and implies a novel rationale for the targeting of cancer therapy.

Cell Division↗
PubMed1996

Expression of Fos-like immunoreactivity in the brain of quail chick emitting the isolation-induced distress calls.

The social isolation intensively induces distress call in neonatal chicks of Japanese quail. The brain regions activated during the isolation were mapped using immunocytochemical detection of c-Fos (the product of immediate early gene c-fos). Fos-like immunoreactivity was observed in a variety of brain regions in isolated chicks that had emitted distress calls. The density of Fos-positive cells in dorso-medial mesencephalic areas (including the intercollicular nucleus and the central gray) was much higher than those of control animals that were kept in groups and emitted very few or no distress calls, whereas the distribution partially overlapped in isolated and control animals. These data, in addition to our lesion and stimulation studies, provide anatomical support for the involvement of the mesencephalic regions in generating distress calls during social isolation.

Animals↗
PubMed1996

Structural characterization of a novel glycoinositolphospholipid from the parasitic nematode, Ascaris suum.

A novel glycosphingolipid containing inositol phosphate as an acidic group has been demonstrated in whole tissues of the porcine roundworm, Ascaris suum. The thin layer chromatographic pattern of the total acidic glycolipid revealed the presence of several components, of which a major component (named AGL) with positive reactions toward both orcinol-sulfuric acid (sugar) and molybdate (phosphate) spray reagents was isolated and purified by the use of successive column chromatography on DEAE-Sephadex and silicic acid (latrobeads). From structural studies including compositional sugar analysis, hydrogen fluoride degradation, methylation analysis, periodate oxidation, proton magnetic resonance spectroscopy and fast atom bombardment mass spectrometry, the structure of AGL was deduced to be Gal alpha 1-2Ins(1-->)-P-Cer. Aliphatic constituents were lignoceric acid and its 2-hydroxy homologue as the principal fatty acids, and octadecasphinganine and branched heptadecasphinganine as the major sphingoids.

Animals↗
PubMed1996

Enzyme-linked immunosorbent assay and latex agglutination inhibition reaction test for morphine in urine.

An enzyme-linked immunosorbent assay (ELISA) and a latex agglutination inhibition reaction test (LAIRT) for morphine have been established. Rabbits were immunized with 3-carboxymethylmorphine-bovine serum albumin (BSA) conjugate to obtain anti-morphine antibody and IgG fraction of the antiserum was used as an antibody. In ELISA, 3-carboxymethylmorphine-alkaline phosphatase (ALP) conjugate and antibody adsorbed on polystyrene microtiter wells were used. The enzyme activity of antibody bound ALP was measured with the enzyme cycling method. The range of morphine measurable by ELISA was 6-600 pg/well and the analysis time for 96 wells was 90 min. In LAIRT, 3-carboxymethylmorphine-rabbit serum albumin (RSA) conjugate and the antibody were bound to latex particles covalently to prepare latex-antigen and latex-antibody reagent, respectively. The agglutination reaction with latex-antigen and latex-antibody reagents was inhibited by 0.2 microgram morphine/ml urine and the analysis time for six samples on one glass slide was 20 min. The urine samples of 47 suspected abusers were analyzed by ELISA and LAIRT and the results were compared with those of the enzyme-multiplied immunoassay technique (EMIT) and gas chromatography/mass spectrometry (GC/MS). Both ELISA and LAIRT for morphine seem to be suitable for the screening of urine samples.

Animals↗
PubMed1996

Forensic immunochemistry.

Immunoassay has been established with polyclonal or monoclonal antibody even for a low molecular weight compound which has no antigenicity. In spite of the cross-reactivities of an antibody and also the difficulty in identification of the compound, an immunoassay is a useful method of choice for the detection of the compound in biological fluids because of the pretreatment simplicity and ability to treat many samples in a short time. Therefore, immunoassay has been established as a sensitive analytical and screening method for use in forensic sciences. In our laboratory, a radioimmunoassay (RIA) and an enzyme immunoassay (EIA) for phenobarbital, and enzyme-linked immunosorbent assays (ELISA) and latex agglutination inhibition reaction tests (LAIRT) for methamphetamine, benzoylecgonine and morphine have been established. These assays are described in addition to the two commercially available immunoassay kits, enzyme multiplied immunoassay technique (EMIT; Syva Co., USA) and Triage Biosite Piagnostics, Inc, USA.

Central Nervous System Agents↗
PubMed1996

Role of bilirubin as an antioxidant in an ischemia-reperfusion of rat liver and induction of heme oxygenase.

The anti-oxidative effect of bilirubin was investigated in an ischemia-reperfusion model of rat liver. The rat portal vessel and liver artery were ligated with a vascular clip, and after reperfusion the urine was collected at intervals. The amount of biopyrrins, the oxidative metabolites of bilirubin, in rat urine reached a maximum 4 hours after reperfusion. Biotripyrrin-a and -b which are biopyrrins isolated from human urine were included in urinary bilirubin oxidative metabolites of rats after reperfusion. The hepatic mRNA level of heme oxygenase-1 (HO-1), the rate limiting enzyme of bilirubin biosynthesis, reached a maximum after 4 hours. Furthermore, the hepatic activity of HO began to rise 4 hours after treatment and remained high until 24 hours posttreatment. These findings suggest that bilirubin acts as a physiological antioxidant in vivo in ischemia-reperfusion and that bilirubin biosynthesis is evoked by oxidative stress.

Animals↗
PubMed1996

Mature T cell reactivity altered by peptide agonist that induces positive selection.

Recent studies have investigated how defined peptides influence T cell development. Using a T cell receptor-transgenic beta2-microglobulin-deficient model, we have examined T cell maturation in fetal thymic organ cultures in the presence of various peptides containing single-alanine substitutions of the strong peptide agonist, p33. Cocultivation with the peptide A4Y, which contains an altered T cell contact residue, resulted in efficient positive selection. Several in vitro assays demonstrated that A4Y was a moderate agonist relative to p33. Although A4Y promoted positive selection over a wide concentration range, high doses of this peptide could not induce clonal deletion. Thymocytes maturing in the presence of A4Y were no longer able to respond to A4Y, but could proliferate against p33. These studies demonstrate that (a) peptides that induce efficient positive selection at high concentrations are not exclusively antagonists; (b) some agonists do not promote clonal deletion; (c) positive selection requires a unique T cell receptor-peptide-major histocompatibility complex interaction; and (d) interactions with selecting peptides during T cell ontogeny may define the functional reactivity of mature T cells.

Amino Acid Sequence↗
PubMed1996

Enzyme-linked immunosorbent assay and latex agglutination inhibition reaction test for cocaine and benzoylecgonine in urine.

An enzyme-linked immunosorbent assay (ELISA) and a latex agglutination inhibition reaction test (LAIRT) for cocaine and benzoylecgonine have been established. In ELISA with polystyrene microtiter wells coated with anti-benzoylecgonine antibody and alkaline phosphatase (ALP)-labeled benzoylecgonine, the activity of antibody-bound ALP was measured with the enzyme cycling method. The range of benzoylecgonine measurable by ELISA was 12 pg-25 ng/well; the analysis time for 96 wells was 90 min. In LAIRT, the agglutination reaction with anti-benzoylecgonine antibody-coated latex and benzoylecgonine-rabbit serum albumin (RSA) conjugate-coated latex was inhibited by 0.1 mu g benzoylecgonine/ml urine; the analysis time for six samples on one glass slide was 20 min. The urine samples of 47 abusers were analyzed by ELISA and LAIRT. From the comparison with results of the enzyme-multiplied immunoassay technique (EMIT) and gas chromatography-mass spectrometry (GC-MS), it was clarified that both ELISA and LAIRT were suitable for the screening method of urine samples.

Animals↗
PubMed1996

Heme oxygenase-1 expression and its relation to oxidative stress during primary culture of cardiomyocytes.

The inducible form of heme oxygenase (heme oxygenase-1) is a heat shock protein 32 (HSP32) whose expression is induced by numerous agents, including heme compounds and heavy metals, and during oxidative stress. The purpose of this study was to examine whether heme oxygenase-1 is induced during primary cell culture of cardiomyocytes and the relation of heme oxygenase-1 expression to oxidative stress levels. Western blot analysis and reverse transcription-polymerase chain reaction analysis showed heme oxygenase-1 expression 12-48 h after isolation of rat neonatal cardiomyocyte for culture. Its expression was barely detected immediately after isolation. Actinomycin D or cycloheximide completely suppressed such expression. Myocardial cells were exposed to oxidative stress during the first 12 h after isolation as assessed by their glutathione redox state; the ratio of reduced glutathione/oxidized glutathione was less than 10. The expression of heme oxygenase-1 was significantly reduced by treatment with reduced glutathione (58% reduction, P < 0.05), but markedly increased by treatment with hydrogen peroxide (65% increase, P < 0.05) 12 h after isolation. Expression of heat shock protein 70 was not significantly changed during primary culture incubation. Results indicate that heme oxygenase-1 is expressed during primary culture of cardiomyocytes. Its expression is closely related to the oxidative stress level of the cultured cells.

Animals↗