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Biomedical subjects

A Okamoto

Publications and source records attributed to A Okamoto.

At least 73 records · Page 4Linked to original sources
PubMed2000

Efficient production of N-terminally truncated biologically active human interleukin-6 by Bacillus brevis.

cDNAs encoding human interleukin 6 (hIL-6) and its variants lacking the N-terminal Pro and Pro-Val-Pro-Pro, respectively, were expressed in Bacillus brevis by using the signal peptide fusion approach. The presence of Pro at the N-terminus of the mature protein hindered the action of the Bacillus brevis signal peptidase. hIL-6 lacking the N-terminal Pro-Val-Pro-Pro was most efficiently secreted in a biologically active form and accumulated in the culture medium to a level of 200 mg per liter, which is the highest level reported for the bacterial secretion of hIL-6.

Amino Acid Sequence↗
PubMed2000

WDX study of resin-dentin interface on wet vs. dry dentin.

The purpose of the present study was to determine the resin-dentin Interface conditions in Wet vs. Dry Dentin. Dentin disks were prepared from extracted human premolars. Sectioned dentin surfaces were used for SEM studies of wet vs. dried acid-etched dentin. These specimens were cut perpendicular to the surface into two equal halves. One-half of the sectioned specimen was observed by SEM in three treatment groups and the other half was observed for micromorphological differences in the resin-dentin interface using Wavelength Dispersive X-ray Spectrometer (WDX). SEM photomicrographs of the dentin surface showed the collapse of collagen fibrils in the demineralized layer and enlargement of the tubule orifices. A collagen rich layer approximately 8-10 microns thick (WDX) was observed at the resin-dentin interface when treated with the conventional dry-bonding technique. Dentin surfaces treated by the wet-bonding technique (SB), as observed by SEM, showed an uncollapsed collagen layer, while the collagen-rich layer was approximately 1-2 microns thick (WDX). The present findings suggest that moist bonding is required for optimum infiltration of adhesive resin into the demineralized layer.

Acid Etching, Dental↗
PubMed2000

[Werner's syndrome associated with acute myelofibrosis].

A 47-year-old man was admitted to our hospital in June 1997 because of nasal bleeding. He presented with anemia in addition to physical characteristics of Werner's syndrome (WS). Peripheral blood examination disclosed pancytopenia with 4% blasts. Bone marrow aspiration was a dry tap; biopsy specimens revealed myelofibrosis. Chromosomal analysis of peripheral blood revealed hypodiploidy with complex abnormalities including -5 and del(7)(q21). Serum levels of PDGF, FGF, and TGF beta 1 were normal. A diagnosis of acute myelofibrosis was made. The patient's condition became quickly deteriorated and he died of pneumonia in October 1997. In the literature, we found 6 reported cases of myelofibrosis associated with WS. Considering that only approximately 1,100 cases of WS have been reported so far, the incidence of myelofibrosis in WS seems relatively high. This case suggested a link between WS and myelofibrosis, and the mechanism of myelofibrosis in WS was discussed.

Acute Disease↗
PubMed2000

[Autologous transplantation of Ph-negative peripheral blood stem cells for treatment of chronic myelogenous leukemia].

A 21-year-old man, diagnosed in March 1997 as having chronic myelogenous leukemia (CML), received hydroxyurea followed by daily interferon (IFN) until December 1998, when the additional chromosome abnormality of +8 appeared. As no suitable matched donor was available, the patient received mobilization therapy consisting of mini-ICE (idarubicin, cytarabine, etoposide) followed by G-CSF subcutaneously. During hematopoietic recovery, a total of 12 x 10(6)/kg CD34-positive cells were harvested. Cytogenetic analysis of peripheral blood stem cell (PBSC) products using FISH revealed 1% BCR/ABL fusion signals. In March 1999, he received conditioning therapy consisting of busulfan (16 mg/kg) and cyclophosphamide (120 mg/kg) followed by infusion of 5 x 10(6)/kg CD34-positive cells. A neutrophil count of 500/microliter and a platelet count of 5 x 10(4)/microliter were attained by days 20 and 38, respectively. Bone marrow aspirates showed 2.6% BCR/ABL fusion signals on day 35 after autologous PBSC transplantation, and the patient remained in chronic phase until the sixth month, when a cytogenetic relapse (Ph, +8:4/20) occurred. These observations suggest that Ph-negative progenitor cells can be harvested using a mini-ICE regimen followed by G-CSF, and that autologous PBSC transplantation is feasible in patients with CML resistant to IFN.

Adult↗
PubMed2000

Immunohistochemical localization of pancreatic secretory trypsin inhibitor in malignant pancreatic endocrine tumors.

Differentiation of benign from malignant pancreatic endocrine tumors by existing clinical, biochemical, histologic, and cytologic criteria is difficult. We immunohistochemically localized pancreatic secretory trypsin inhibitor (PSTI) in 28 pancreatic endocrine tumors (13 benign, 15 malignant). PSTI-immunoreactive cells were detected in nine endocrine tumors. Immunoreactivity in these tumors was detected in nearly all tumor cells in five cases, scattered cells in two cases, and a few cells in two cases. All positive cases were malignant, and eight were equal to or larger than 10 cm. Serum concentrations of PSTI were markedly elevated in the two patients so tested. PSTI may be a specific immunohistochemical marker for malignant pancreatic endocrine tumors.

Adult↗
PubMed1999

Intraoperative radiotherapy for resectable extrahepatic bile duct cancer.

PURPOSE: Through a retrospective study of intraoperative radiation therapy (IORT) in bile duct cancer, we hope to help clarify its clinical usefulness. METHODS AND MATERIALS: Between 1976 and 1996, IORT was carried out in 35 patients with bile duct cancer at the Tokyo Metropolitan Komagome Hospital. Of the 35 patients, resection proved to be curative in 15. Intraoperative irradiation of 15-30 Gy (average 20.1 Gy) was delivered by electron beam in the 5- to 19-MeV energy ranges. Postoperative external-beam radiation therapy (EBRT) was also delivered in 16 patients. The EBRT was fractionated to 2 Gy/day, in principle, and was delivered at 8.8-54 Gy (average 40.4 Gy) by 10-MV X-rays. RESULTS: The median survival in our patients was 19 months. The 1-year, 2-year, and 5-year survival rates were 57%, 43%, and 19%, respectively. Statistical analysis identified the following prognostic factors: performance status, curative surgical resection, lymph node metastasis, IORT dosage, and treatment period. Only 1 patient (3%) died within 30 days after surgery, and the incidence of late-onset complications was 21%. CONCLUSION: The combination of IORT and EBRT is useful for patients with bile duct cancer who undergo noncurative resection or who have lymph node metastasis.

Adult↗
PubMed1999

Alterations of the PPP1R3 gene in human cancer.

Recently, the PTEN/MMAC1 gene encoding a protein phosphatase (PP) and the PPP2R1B gene encoding a regulatory subunit of PP2A have been identified as being genetically altered in several types of human cancers, indicating that aberrations of intracellular signaling pathways via PPs are involved in human carcinogenesis. Here we report genetic alterations of the PPP1R3 gene located at chromosome 7q31, which encodes regulatory subunit 3 of PP1, in various types of human cancers. Mutations of the PPP1R3 gene were detected in 5 of 33 (15%) non-small cell lung cancer cell lines and 2 of 38 (5%) primary non-small cell lung cancers and were also observed in cell lines derived from a small cell lung cancer, an ovarian cancer, a colorectal cancer, and a gastric cancer. Mutations were widely dispersed in the coding region of the PPP1R3 gene. Three of the 11 detected mutations were nonsense mutations, whereas the remaining ones were missense mutations, most of which caused substitutions of evolutionarily conserved amino acids. These findings suggest that PPP1R3 alteration plays a role in the development of human cancers and that PPP1R3 could act as a tumor suppressor gene.

Amino Acid Sequence↗
PubMed1999

Synthesis and antitumor activity of duocarmycin derivatives: modification of segment-A of A-ring pyrrole compounds.

A series of 3-substituted A-ring pyrrole compounds of duocarmycin were synthesized and evaluated for in vitro anticellular activity against HeLa S(3) cells and in vivo antitumor activity against murine sarcoma 180 in mice. These compounds were evaluated on the peripheral blood toxicity and delayed lethal toxicity. Further, to expand our investigation of their peripheral blood toxicity, the toxicity to bone marrow cells (CFU-GM, CFU-Meg) was investigated. Among 3-substituted A-ring pyrrole compounds of duocarmycin bearing a 5',6',7'-trimethoxy-2'-indolecarboxyl group as segment-B (Seg-B), several analogues showed remarkably potent antitumor activity with low peripheral blood toxicity. The 3-formyl compound 12h, one of such analogues, showed stronger antitumor activity with lower toxicity to bone marrow cells compared to DU-86 (2a), an active metabolite of KW-2189 (2b). However, compound 12h caused delayed death. On the other hand, the 3-bromo compound 15f, one of the 3-substituted A-ring pyrrole derivatives bearing a 4'-methoxycinnamoyl group as Seg-B, showed the most potent antitumor activity among the 4'-methoxycinnamate analogues with low toxicity to bone marrow cells. Furthermore, compound 15f did not cause delayed death similarly to 2d. These results would indicate the importance of the C-3 substituents of A-ring pyrrole duocarmycin derivatives for exhibiting antitumor activity and decreasing toxicity.

Animals↗
PubMed1999

The active site of Paracoccus denitrificans aromatic amino acid aminotransferase has contrary properties: flexibility and rigidity.

Paracoccus denitrificans aromatic amino acid aminotransferase (EC 2. 6.1.57; pdAroAT) binds with a series of aliphatic monocarboxylates attached to the bulky hydrophobic groups. To analyze the properties of the active site in this enzyme, we determined the tertiary structures of pdAroAT complexed with nine different inhibitors. Comparison of these active site structures showed that the active site of pdAroAT consists of two parts with contrary properties: rigidity and flexibility. The regions that interact with the carboxylates and methylene chains of the inhibitors gave essentially the same structures among these complexes, exhibiting the rigid property, which would involve fixing the substrate at the proper orientation for efficient catalysis. The region that interacts with the terminal hydrophobic groups of the inhibitors gave versatile structures according to the structures of the terminal groups, showing that this region is structurally flexible. This is mainly achieved by the conformational versatility of the side chains of Asp15, Lys16, Asn142, Arg292, and Ser296. These residues formed in the active site hydrogen bond networks, which were adaptable for the structures of the terminal hydrophobic groups of the inhibitors, with a small deformation or partial destruction according to the shapes and sizes of the inhibitors. These observations illustrate how the flexibility and rigidity in the active site can be used for the substrate binding and recognition.

Acids, Acyclic↗
PubMed1999

Redesigning the substrate specificity of an enzyme by cumulative effects of the mutations of non-active site residues.

Directed evolution was used to change the substrate specificity of aspartate aminotransferase. A mutant enzyme with 17 amino acid substitutions was generated that shows a 2.1 x 10(6)-fold increase in the catalytic efficiency (kcat/Km) for a non-native substrate, valine. The absorption spectrum of the bound coenzyme, pyridoxal 5'-phosphate, is also changed significantly by the mutations. Interestingly, only one of the 17 residues appears to be able to contact the substrate, and none of them interact with the coenzyme. The three-dimensional structure of the mutant enzyme complexed with a valine analog, isovalerate (determined to 2.4-A resolution by x-ray crystallography), provides insights into how the mutations affect substrate binding. The active site is remodeled; the subunit interface is altered, and the enzyme domain that encloses the substrate is shifted by the mutations. The present results demonstrate clearly the importance of the cumulative effects of residues remote from the active site and represent a new line of approach to the redesign of enzyme activity.

Amino Acid Sequence↗
PubMed1999

Allelic imbalance in chromosome band 18q21 and SMAD4 mutations in ovarian cancers.

Recently, three candidate tumor suppressor genes, SMAD2 (MADR2/JV18-1), SMAD4 (DPC4), and DCC, were identified in chromosome band 18q21. We examined allelic imbalance (AI) in 18q21 using six polymorphic microsatellite markers in 38 primary ovarian cancers and four ovarian borderline tumors. AI at one or more loci was detected in 15 of 37 (41%) informative ovarian cancers and in none of the four borderline tumors. Frequent AI was detected at the D18S46 (31%) and D18S474 (36%) loci, which were adjacent to the SMAD4 gene, and at the D18S69 (33%) locus, which was telomeric to the DCC gene. Therefore, we searched for mutations of the SMAD4 gene in 42 primary tumors and eight cell lines by PCR-SSCP and sequencing analyses. Missense mutations were detected in two ovarian tumors and three ovarian cancer cell lines, whereas silent mutation was detected in a primary ovarian cancer. These results suggest that there are at least two tumor suppressor genes on chromosome arm 18q and that SMAD4 is of importance in ovarian tumorigenesis.

Alleles↗
PubMed1999

Successful peripheral blood stem cell transplantation for myelodysplastic syndrome.

Wilms' tumor (WT1) gene expression is increased in patients with leukemia as well as myelodysplastic syndrome (MDS) and is useful for detection of minimal residual disease (MRD). A 47-year-old man given a diagnosis of refractory anemia with excess of blasts in transformation (RAEB-T) received myeloablative therapy followed by autologous peripheral blood stem cell transplantation (PBSCT). MRD by WT1 expression was not detected in the graft. The patient has been in CR for 25 months after PBSCT. These observations suggest that PBSCT is feasible for patients with RAEB-T and analysis of WT1 expression can be applied for patients with high risk MDS.

Anemia, Refractory, with Excess of Blasts↗
PubMed1999

A calculation method for the range of occluding phase at the lower incisal point during chewing movements using the curved mesh diagram of mandibular excursion (CMDME).

The purpose of this study was to develop a method for calculating the range of the occluding phase in chewing movements. In this study, we defined 'range' as the distance of the movement at the lower incisal point while the mandible moves with tooth contact. First, mandibular excursions were measured using an opto-electronic movement analysis system, which can measure mandibular movement with six degrees-of-freedom at a sampling frequency of 100 Hz. With use of this measurement data, the curved mesh diagram of mandibular excursion (CMDME) previously reported was made. Then, chewing movements were measured using the same analysis system. The movements were separated into their component chewing cycles. Finally, we calculated the distance between each cycle and the CMDME. The occluding range of our subject was 0.4 mm at the closing phase and 3.4 mm at the opening phase. These results suggest that tooth contact occurs during chewing movement and demonstrate that the range of the occluding phase for the opening and closing phases of a subject can be calculated without morphological data from a dental cast.

Adult↗
PubMed1999

B-cell lymphoma associated with haemophagocytic syndrome: a clinical, immunological and cytogenetic study.

B-cell lymphoma associated with haemophagocytic syndrome (HPS) is extremely rare in Western countries but has recently been increasingly reported in Asian countries. We describe seven patients with B-cell lymphoma associated with HPS, six males and one female, age range 41-82 years (median 63 years). All patients had fever and splenomegaly, and six of the seven patients had hepatomegaly with no associated lymphadenopathy. The bone marrow showed haemophagocytosis and an infiltration of lymphoma cells. All patients showed increased levels of lactate dehydrogenase, C-reactive protein, ferritin and soluble interleukin-2 receptor. Lymphoma cells were positive for CD19. CD20 and surface immunoglobulin in all patients examined, and positive for CD5 in four of seven patients. Cytogenetic analyses of bone marrow cells showed a complex structural abnormality including chromosome 14q32 in two patients, 19q13 in three patients and deletion of the terminal part of 8p21 in six patients. The prognosis was poor; only two of the seven patients have survived in complete remission with a median survival of 11 months. These data suggested that B-cell lymphoma associated with HPS might constitute a distinct biological and clinical disease entity. Abnormality of chromosome 19q13 and loss of 8p21 might be involved in the pathogenesis of this disease.

Adult↗
PubMed1999

Synthesis and antitumor activity of duocarmycin derivatives: a-ring pyrrole compounds bearing 5-membered heteroarylacryloyl groups.

A series of A-ring pyrrole compounds of duocarmycin bearing 5-membered heteroarylacryloyl groups (thienylacryloyl and pyrrolylacryloyl) and heteroarylcarbonyl groups were synthesized and evaluated for in vitro anticellular activity against HeLa S3 cells and in vivo antitumor activity against murine sarcoma 180 in mice. Most of the thienylacrylates displayed in vitro anticellular activity equivalent to 4'-methoxycinnamates. Among the 8-O-[(N-methylpiperazinyl)carbonyl] derivatives of methoxy-thienylacrylates, compound 11b, having 4'-methoxy-2'-thienylacryloyl as segment-B (Seg-B), showed remarkably potent antitumor activity and low peripheral blood toxicity in vivo, which were equal to those of 8-O-[(N-methylpiperazinyl)carbonyl] derivatives of 4'-methoxycinnamates, compared with the A-ring pyrrole derivatives having the trimethoxyindole skeleton in Seg-B. On the other hand, the 2'-pyrrolylacrylates having a double bond as spacer showed 10(2)- to 10(3)-fold stronger anticellular activity than 2'-pyrrolecarboxylates (IC50 < 0.3 nM, 72 h-exposure). The 8-O-acetate and 8-O-[(N-methylpiperazinyl)carbonyl] derivatives of 2'-pyrrolylacrylates exhibited an antitumor effect at a lower dose compared with the 8-O-[(N-methylpiperazinyl] derivatives of 4'-methoxycinnamate (1j). Moreover, it was expected that the antitumor activity would be increased by the strength of the extra hydrogen bond formed between the nitrogen of the pyrrole amido group and DNA, owing to the increase of the number of N-methyl-2'-pyrrolecarboxamide units. However, 2'-pyrrolylacrylates having three N-methyl-2'-pyrrolecarboxamide units showed nearly equal antitumor activity to 2'-pyrrolylacrylates having only one N-methyl-2'-pyrrolecarboxamide unit.

Acrylates↗
PubMed1999

A dynamic change by 123I-15-(p-iodophenyl)-3-R,S-methyl pentadecanoic acid myocardial single photon emission computed tomography in a 55-year-old woman.

A 55-year-old woman was admitted to hospital with chest discomfort. Emergency angiography revealed no organic stenosis in the coronary artery, but there was akinesis in the apico-anteroseptal region of the left ventricle. Left ventriculography on the 5th day after admission was normal. On the 2nd day, initial imaging by 123I-15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) myocardial single photon emission computed tomography (SPECT) indicated a slight decrease in tracer uptake and delayed imaging revealed fill-in in the apicoanteroseptal regions in spite of akinesis in those areas. On the 4th day, initial imaging by 123I-BMIPP showed a moderate decrease in tracer uptake and delayed imaging revealed a high washout again in those areas. On the 12th day, initial imaging by 123I-BMIPP showed a severely reduced uptake in the apico-anteroseptal regions and delayed imaging disclosed a high washout, in the same areas that showed akinesis during the acute phase. On the 35th day, 123I-BMIPP identified no significant decrease in tracer uptake. It is suggested that these dynamic changes in 123I-BMIPP myocardial SPECT imaging may reflect the metabolic change of fatty acid in the ischemic state, the size and degree of turnover of the triacylglycerol pool.

Fatty Acids↗