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Biomedical subjects

S Okamoto

Publications and source records attributed to S Okamoto.

At least 307 records · Page 17Linked to original sources
PubMed1996

Monoclonal antibody against the fusion junction of a deletion-mutant epidermal growth factor receptor.

A mouse monoclonal antibody (IgG2b), 3C10, was produced against the truncated epidermal growth factor receptor (EGFR), encoded by the (type III) in-frame deletion mutation of 801 nucleotides of EGFR affecting the external domain, known to be expressed in some human glioblastoma. As this mutation newly generates a glycine residue at the fusion point, a 14 amino acid peptide around the fusion junction including this glycine was chemically synthesised and used for immunisation of (B6 x DBA/2) F1 mice. Flow cytometric analysis showed 3C10 antibody staining of a mouse NIH/3T3 transfectant (ERM5) with the type III EGFR deletion-mutant gene, but not one with wild-type EGFR. The antibody immunoprecipitated the truncated EGFR protein with a molecular mass of approximately 140 kDa from ERM5 cells. Immunostaining of glioblastomas revealed binding in the case with the type III EGFR mutation, the five other specimens without the mutation being negative despite overexpression of EGFR in some cases.

3T3 Cells↗
PubMed1996

Serial quantification of minimal residual disease of t(8;21) acute myelogenous leukaemia with RT-competitive PCR assay.

The chromosomal translocation (8;21)(q22;q22) in the AML M2 subtype according to the FAB classification, results in the production of a novel fusion gene AML1/ETO. The chimaeric AML1/ETO transcript is useful for the detection of minimal residual disease (MRD). Recently, several studies on the detection of AML1/ETO transcripts in t(8;21) AML have been reported. However, the clinical significance of a small number of AML1/ETO transcripts by a reverse transcription-polymerase chain reaction (RT-PCR) remains to be elucidated. We have developed a novel quantitative RT-competitive PCR assay and evaluated the clinical usefulness of this method by the monitoring of MRD in eight patients with t(8;21) AML. In four patients in first continuous complete remission (CR) the value of MRD was always < 0.1 fg of the competitor dose throughout their courses, whereas in four relapsed patients there was an increase in the value of MRD to > 0.1 fg of the competitor dose before cytogenetic relapse. We conclude that the detection of the presence of cells with AML1/ETO fusion transcripts by our RT-competitive PCR assay may be useful to monitor disease progression and to predict subsequent relapse.

Aged↗
PubMed1996

Characterization of the purified cytosolic thymidine kinase from murine ehrlich ascites tumor: interconversion of two different relative molecular weight forms.

Cytosolic thymidine kinase was purified 18,000-fold of the homogenate from murine Ehrlich ascites tumor, using the [p-aminophenyl 3' -dTMP]-CH-Sepharose affinity column. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme showed a single protein band of molecular weight 26,000. Two different forms, relative molecular weight 50,000 and 70,000, were found by gel filtration, depending on the existence of dithiothreitol, ATP and other nucleotides. These agents also stabilize and stimulate the enzyme activity. The existence of two forms was also manifested by DEAE-Sephacel column chromatography, where the 50,000 form was eluted by 50 mM NaCl and the 70,000 form by 400 mM NaCl.

Adenosine Triphosphate↗
PubMed1996

Isolation of a new superantigen with potent mitogenic activity to murine T cells from Streptococcus pyogenes.

A mitogenic substance on murine lymphocytes was detected in the culture supernate of Streptococcus pyogenes type 12 strain. This substance had a molecular weight of 28,000 and pI 9.2, and was designated as S. pyogenes mitogen (SPM). The proliferative response of C3H/HeN spleen cells began at 1 ng ml-1 and reached a maximal response at 100 ng ml-1 of SPM for 4 days culture. Anti-Thy 1.2 mAb and complement-treated spleen cells abrogated the proliferative response to any dose of SPM. Although the anti-major histocompatibility complex class 1 mAbs had no blocking effect on proliferation by SPM, this proliferation was substantially inhibited by the addition of either anti-I-A or anti-I-E mAb, and complete inhibition was produced by the addition of both mAbs. Fixed antigen-presenting cells still induced T cell proliferation by SPM. A significant expansion of T cells bearing V beta 13 T-cell receptor was observed up to 73% among the Thy 1.2+ cells in cultures stimulated with SPM, indicating expansion in a V beta-specific manner. Immunoblotting of IEF-separated proteins showed that anti-streptococcal pyrogenic exotoxin (SPE) C reacted with a protein of pI 6.9 and anti-SPEB did not show any reactivity. SPEA was reported to expand V beta 8.1 and 8.2 bearing murine T cells, and SPM did not. SPM also exhibited potent mitogenic activity on human T cells and V beta 21+ T cells were selectively expanded. These results lead to the conclusion that SPM was neither SPEA, B nor C, but a new protein belonging to a group of streptococcal superantigens with activity on not only human but also murine lymphocytes.

Animals↗
PubMed1996

Expression of Salmonella typhimurium rpoS and rpoS-dependent genes in the intracellular environment of eukaryotic cells.

Adaptation to the intracellular environment of host cells is crucial for the pathogenesis of Salmonella infections. The alternative sigma factor RpoS is a global regulator of gene expression during starvation and stress conditions and is required for virulence in Salmonella spp. We have used lacZ reporter fusions to rpoS and rpoS-dependent genes to study rpoS regulation after entry of Salmonella typhimurium into macrophages and epithelial cells. The results demonstrate that expression of an rpoS::lacZ translational fusion increases rapidly in S. typhimurium after phagocytosis. Activity of RpoS also increases after bacterial entry into both macrophages and epithelial cells, as demonstrated by the induction of the rpoS-regulated genes katE and spvB. A control rpoS-independent promoter for neomycin resistance does not show significant induction after cell entry. These results demonstrate that the regulatory system mediated by RpoS in S. typhimurium is activated by the intracellular environment of eukaryotic cells.

Animals↗
PubMed1996

Induction of actinorhodin production by rpsL (encoding ribosomal protein S12) mutations that confer streptomycin resistance in Streptomyces lividans and Streptomyces coelicolor A3(2).

A strain of Streptomyces lividans, TK24, was found to produce a pigmented antibiotic, actinorhodin, although S. lividans normally does not produce this antibiotic. Genetic analyses revealed that a streptomycin-resistant mutation str-6 in strain TK24 is responsible for induction of antibiotic synthesis. DNA sequencing showed that str-6 is a point mutation in the rpsL gene encoding ribosomal protein S12, changing Lys-88 to Glu. Gene replacement experiments with the Lys88-->Glu str allele demonstrated unambiguously that the str mutation is alone responsible for the activation of actinorhodin production observed. In contrast, the strA1 mutation, a genetic marker frequently used for crosses, did not restore actinorhodin production and was found to result in an amino acid alteration of Lys-43 to Asn. Induction of actinorhodin production was also detected in strain TK21, which does not harbor the str-6 mutation, when cells were incubated with sufficient streptomycin or tetracycline to reduce the cell's growth rate, and 40 and 3% of streptomycin- or tetracycline-resistant mutants, respectively, derived from strain TK21 produced actinorhodin. Streptomycin-resistant mutations also blocked the inhibitory effects of relA and brgA mutations on antibiotic production, aerial mycelium formation or both. These str mutations changed Lys-88 to Glu or Arg and Arg-86 to His in ribosomal protein S12. The decrease in streptomycin production in relC mutants in Streptomyces griseus could also be abolished completely by introducing streptomycin-resistant mutations, although the impairment in antibiotic production due to bldA (in Streptomyces coelicolor) or afs mutations (in S. griseus) was not eliminated. These results indicate that the onset and extent of secondary metabolism in Streptomyces spp. is significantly controlled by the translational machinery.

Alleles↗
PubMed1996

Lactate distribution and metabolism during and after anoxia in the turtle, Chrysemys picta bellii.

To determine the fate of lactate during and after prolonged anoxia, 14C-labeled lactate was injected into turtles after 2 h of a 6-h submergence at 20 degrees C. 14C activities of plasma and chamber water were tested at intervals during anoxia and also in expired air during 39 h of recovery. Partitioning of label in major body compartments [extracellular fluid (ECF), intracellular fluid (ICF), and shell] and 14C activity and glycogen in selected tissues (heart, liver, and muscle) were measured after anoxia (n = 7) and after recovery (n = 6). Shell 14C and [lactate] were extensively measured on six anoxic turtles. During anoxia all 14C remained in the animal indicating no urine production. At 6 h of anoxia 47% of recovered 14C, presumably still as lactate, was in the ECF, 27% in the ICF, and 30% in the shell. During recovery, plasma [lactate] fell from 35 to 5 meq, but surrounding water and expired air accounted for only 9 and 8%, respectively, of recovered label. The ICF portion grew to 41%, associated with a recovery in tissue glycogen. The shell still had 22% of total label. We conclude that, during recovery from anoxia, lactate is predominantly resynthesized to glycogen, and only a small fraction is directly oxidized. During anoxia, however, lactate is widely distributed in the body, and a surprisingly large and functionally significant fraction resides in the shell.

Animals↗
PubMed1996

Major salivary gland lesions: correlation of MR findings with flow cytometric DNA analysis and prognosis.

OBJECTIVE: We correlated MR imaging findings with those from flow cytometry and determined prognostic factors of patients with major salivary gland lesions. SUBJECTS AND METHODS: DNA ploidy (11 aneuploid, 35 diploid lesions) and S-phase fraction (SPF) (12 high-SPF, 28 low-SPF lesions) percentages as determined by flow cytometric technique in 46 major salivary gland lesions were correlated with MR findings and signal-intensity ratios of lesion to muscle on fast spin-echo T2-weighted images, unenhanced spin-echo T1-weighted images, and gadolinium-enhanced fat-suppressed spin-echo T1-weighted images. SPF percentages were correlated with the three signal-intensity ratios by stepwise regression analysis. Prognostic indicators of disease-free survival were assessed with Cox multivariate analysis (range of follow-up, 2-50 months; mean, 16.6 months). RESULTS: Signal-intensity ratios for all pulse sequences were significantly smaller in aneuploid lesions than in diploid lesions. Incidence of ill-defined margins (p < .001), invasion (p = .014), and hypointensity to the gland on T2-weighted images (p = .047) was significantly higher in aneuploid lesions than in diploid lesions. Of these, signal-intensity ratios on enhanced T1-weighted images were most accurate for predicting aneuploidy. A threshold of 1.55 for signal-intensity ratios on enhanced T1-weighted images yielded the highest accuracy (86%) for aneuploidy. Signal-intensity ratios on T2-weighted images (p = .025) and enhanced T1-weighted images (p < .001) were significantly smaller in high-SPF lesions than in low-SPF lesions. A threshold of 1.73 for signal-intensity ratios on enhanced T1-weighted images yielded 73% accuracy for high-SPF lesions, which was inferior to the prediction possible from ill-defined margins (80% accuracy). Aneuploidy (p = .008), ill-defined margins (p = .036), and signal-intensity ratios on unenhanced T1-weighted images (p = .008), related significantly and negatively to disease-free survival. A signal-intensity ratio of 1.22 or less for unenhanced T1-weighted images indicated a high risk of developing recurrence (100% sensitivity). CONCLUSION: MR findings and signal-intensity ratios can reflect DNA ploidy and SPF status and can predict prognoses for patients with major salivary gland lesions.

Adolescent↗
PubMed1996

Cutaneous chronic graft-versus-host disease localized to the field of total lymphoid irradiation.

A 20-year-old woman with aplastic anemia underwent bone marrow transplantation from an HLA-identical sibling after total lymphoid irradiation (TLI) and cyclophosphamide (CY). The post-transplant course was uneventful. CYA was discontinued on day 221. Three weeks later, the patient developed cutaneous GVHD precisely localized to the field of TLI. No other organs were involved. Immunohistochemical staining of the affected skin was strongly positive for ICAM-1, PECAM-1 and ELAM-1; normal skin was only weakly positive for ICAM-1. CYA was restarted, and the skin lesions disappeared. TLI may contribute to an unusual presentation of cutaneous GVHD associated with specific expression of adhesion molecules.

Adult↗
PubMed1996

[Proposals for the objective indices for evaluating the differentiation of leukemic cells by all-trans retinoic acid in the patients with acute promyelocytic leukemia].

All-trans retinoic acid (ATRA) is widely used as a differentiation-inducing agent for acute promyelocytic leukemia (APL). However, one of the problems with this therapy is the difficulty in evaluating the extent of differentiation of leukemic cells. To determine objective indices for differentiation which can be used for judging complete remission, we treated 18 patients with acute promyelocytic leukemia, and performed sequential analysis of bone marrow, karyotype, RAR alpha gene rearrangement and PML-RAR alpha fusion gene transcript. The karyotype, RAR alpha rearrangement and PML-RAR alpha transcript returned to a normal pattern on days 31, 2, 34.8 and 47.6, respectively. We defined and analyzed maturation index (MI) by bone marrow findings as follows; (metamylocyte + band neutrophil + segmented neutrophil) (%)/(myeloblast + promyelocyte + myelocyte) (%). MI increased along with the differentiation of leukemic cells, and the days for MI exceeding 2 well correlated with the normalization of karyotype. These results suggested that MI can be used as an index of differentiation during ATRA therapy.

Adolescent↗
PubMed1996

Granisetron in the prevention of vomiting induced by conditioning for stem cell transplantation: a prospective randomized study.

We conducted a prospective randomized study to compare granisetron, a 5-hydroxytryptamine-3 receptor antagonist with standard anti-emetics (control group) consisting mainly of metoclopramide, in the prophylaxis of emesis induced by conditioning prior to stem cell transplantation. Fifty-eight patients were evaluable for analysis. The number of emetic episodes expressed in terms of patient-days was significantly lower in the granisetron group than in the control group (P < 0.001). During the first 24 h of conditioning, 27 of the 31 patients (87.1%) in the granisetron group achieved control of emesis with less than three emetic episodes (major < or = ) a day compared with 37.0% in the control group (P < 0.001). The same degree of emesis control was maintained throughout the conditioning period in 51.% of patients in the granisetron group compared with 0% in the control group (P < 0.001). Adverse reactions were observed in 11.4% of patients in the granisetron group and in 25.9% in the control group. None of the events were serious. Based on these data, we conclude that granisetron is superior to standard antiemetics in protecting against the vomiting induced by conditioning for stem cell transplantation.

Adolescent↗
PubMed1996

Durable molecular remission in a patient with chronic myelogenous leukemia and host-derived hematopoiesis after allogeneic bone marrow transplantation.

A 44-year-old woman with Ph-positive CML was treated with TBI, splenic irradiation, Ara-C, and CY. She then received unmanipulated marrow cells from her HLA-identical brother. GVHD prophylaxis was FK506 and MTX. WBC counts reached 1000/microliter on day 28 when all metaphases of marrow cells showed 46XY. However, on day 42, 46XX was detected in two of 20 metaphases, and the percentage of cells with female karyotype subsequently increased. On day 519, all metaphases showed female karyotype. BCR-ABL mRNA and Philadelphia chromosome were never detected throughout her post-transplant course. Fluorescence in situ hybridization (FISH) revealed complete recovery of host-derived hematopoiesis in the bone marrow, however, mixed T cell chimerism in the peripheral blood. This suggests that the persistence of donor-derived T cells may prevent disease recurrence through graft-versus-leukemia effect. The patient remains in a molecular complete remission with host-derived hematopoiesis 749 days post-transplant.

Adult↗
PubMed1996

[Bronchiolitis obliterans organizing pneumonia (BOOP) after allogeneic bone marrow transplantation].

We report a patient who underwent allogeneic bone marrow transplantation for ALL. The patient presented low grade fever, cough and dyspnea at day 3 after after bone marrow transplantation. Imaging studies showed bilateral patchy infiltrates on chest X-ray and chest CT. Though treated by antibiotics, chest auscultation recognized marked bilateral inspiratory crackles. Transbronchial lung biopsy performed on day 34 showed bronchiolitis obliterans and an organizing interstitial pneumonia. The patient was treated with methylprednisolone and follow up computed tomography findings improved.

Administration, Oral↗
PubMed1996

[Hypertrophic obstructive cardiomyopathy with ruptured chordae tendineae: a case report].

A 61-year-old man with hypertrophic obstructive cardiomyopathy and ruptured chordae tendineae but subsequent disappearance of the obstruction received mitral valve replacement 4 years after the diagnosis of ruptured chordae tendineae. Chordal rupture should be recognized as one of the important causes of mitral regurgitation in patients with hypertrophic obstructive cardiomyopathy.

Cardiomyopathy, Hypertrophic↗