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Biomedical subjects

H Masumoto

Publications and source records attributed to H Masumoto.

At least 73 records · Page 4Linked to original sources
PubMed1992

Centromere protein B assembles human centromeric alpha-satellite DNA at the 17-bp sequence, CENP-B box.

We purified 15,000-fold from HeLa cell nuclear extract the centromere antigen that reacts specifically with the 17-bp sequence, designated previously as CENP-B box, in human centromeric alpha-satellite (alphoid) DNA by a two-step procedure including an oligonucleotide affinity column. The purified protein was identified as the centromere protein B (CENP-B) by its mobility on SDS-PAGE (80 kD), and reactivities to a monoclonal antibody raised to CENP-B (bacterial fusion protein) and to anticentromere sera from patients with autoimmune diseases. Direct binding by CENP-B of the CENP-B box sequence in the alphoid DNA has been proved using the purified CENP-B by DNA mobility-shift assay, Southwestern blotting, and DNase I protection analysis. The binding constant of the antigen to the CENP-B box sequence is 6 x 10(8) M-1. DNA mobility-shift assays indicated that the major complex formed between the CENP-B and the DNA contains two DNA molecules, suggesting the importance of the CENP-B/CENP-B box interaction in organization of higher ordered chromatin structures in the centromere and/or kinetochore. Location of DNA binding and dimerization domains in CENP-B was discussed based on the DNA mobility-shift assays performed with a protein fraction containing intact and partial cleavage products of CENP-B.

Autoantigens↗
PubMed1992

A human centromere protein, CENP-B, has a DNA binding domain containing four potential alpha helices at the NH2 terminus, which is separable from dimerizing activity.

The alphoid DNA-CENP-B (centromere protein B) complex is the first sequence-specific DNA/protein complex detected in the centromeric region of human chromosomes. In the reaction, CENP-B recognizes a 17-bp sequence (CENP-B box) and assembles two alphoid DNA molecules into a complex, which is designated complex A (Muro, Y., H. Masumoto, K. Yoda, N. Nozaki, M. Ohashi, and T. Okazaki. 1992. J. Cell Biol. 116:585-596). Since CENP-B gene is conserved in mammalian species and CENP-B boxes are found also in mouse centromere satellite DNA (minor satellite), this sequence-specific DNA-protein interaction may be important for some kind of common centromere function. In this study we have characterized the structure of CENP-B and CENP-B-alphoid DNA complex. We have shown by chemical cross-linking that CENP-B formed a dimer, and have estimated by molecular weight determination the composition of complex A to be a CENP-B dimer and two molecules of alphoid DNA. The DNA binding domain has been delimited within the NH2-terminal 125-amino acid region containing four potential alpha-helices using truncated CENP-B made in Escherichia coli cells. We have shown that CENP-B had sites highly sensitive to proteases and that the DNA binding domain was separable from the dimerizing activity by the proteolytic cleavage at 20 kD from the COOH terminus of the molecule. Thus, CENP-B may organize a higher order structure in the centromere by juxtaposing two CENP-B boxes in the alphoid DNA repeat through both the DNA-protein and protein-protein interactions.

Amino Acid Sequence↗
PubMed1991

Purification of a human centromere antigen (CENP-B) and application of DNA immunoprecipitation to quantitative assay for anti-CENP-B antibodies.

Centromere protein-B (CENP-B) was purified from HeLa nuclear extract by using a combination of Q-sepharose ion change and oligonucleotide sepharose column chromatography. CENP-B was purified more than 10,000 times and was analyzed by immunoblotting and DNA immunoprecipitation. Purified CENP-B was used as an antigen to develop DNA immunoprecipitation for rapid and specific detection of anti-CENP-B antibody in human sera. In this analysis, none of the tested sera immunoprecipitated DNA alone. All of the 40 anticentromere antibody (ACA)-positive sera immunoprecipitated CENP-B-alphoid DNA fragment complex, whereas 10 healthy control sera and 10 other autoantibody positive sera did not. Five of the ACA-positive sera, which did not show reactivity of CENP-B in immunoblotting analysis, immunoprecipitated CENP-B-DNA complex. In some sera antigenicity to CENP-B may be weakened by denaturation.

Autoantibodies↗
PubMed1991

[A treatment of intractable sternal osteomyelitis--significant use of pedicle muscular flaps].

In recent years, the greater omentum of pedicle muscular flap has been used to treat chest wall infection and Sternal Osteomyelitis following cardiac or respiratory surgery. In Japan, however, there has been an increasing number of cases in which neither the greater omentum Nor the rectus muscle can be used due to the comparatively young age of the patient. There are also many cases undergoing abdominal surgery for malignant tumor and bypass surgery of the coronary artery in which the internal thoracic artery (ITA) and gastroepiploic artery (GEA) are used. We studied three such cases; a case of coronary aortic bypass graft (CABG) where ITA from both the right and left sides were used following stomach resection; a case in which CABG and gallbladder resection were carried out simultaneously; and a case of sternal osteomyelitis is years following surgery for ventricular septal defect. All three cases had undergone reconstructive surgery using the pectoralis major muscle or a pedicle muscular flap from the latissimus dorsi muscle. It is estimated that cases of CABG using both the right and left sides of ITA and GEA, cases of the elderly as well as cases of children will continue to increase. Consequently, cases of sternal osteomyelitis in which neither the omentum nor rectus muscle can be used will also increase. Therefore, it is considered that treatment using pedicle muscular flaps from the breast or dorsal area may be very effective. Herein, we report on the choice of treatment and its results.

Aged↗
PubMed1990

[Radiotherapy of aged cancer patients].

Although it is not a categorized modality, cancers of aged patients, generally characterized by a slow growth, histologically high differentiation and low radiosensitivity due to co-existing chronic anemia, should have more individualized treatment because there is a wide spectrum of differences in functional reservoir and tolerance dose of each organs and individuals. In aged cervical cancer of the uterus, we decrease the fractionated and total irradiation dose of a whole pelvic cavity by 10%. For patients more than 80 years old, we principally abandon external beam and singularly chose an intracavitary treatment. In our protocol, there could find no significant difference in 5 year survival between 51-70 y.o. 51.9% (120/231) and 71-80 y.o. 57% (61/107), but in the over 80 y.o. group, it was decreased to 13.6% (3/22) by increased death of other diseases 61.9% (13/21) compared with 18.4% (36/195) in 51-80 y.o. In radiotherapy of advanced lung cancer in aged, we decreased fractionated and total dose by 10 to 20% with minimum irradiation field. In non-small cell carcinoma, a median survival time was 11.5 months in both over and under 70 y.o., although the response rate (CR + PR) was resulted relatively low in aged, 33.3% (N = 45), compared with under 70 y.o., 38.4 (N = 146). The degrees of impairment in respiratory and bone marrow function were similar in both groups. Accordingly, we convinced the efficacy and the necessity of individualized radiotherapy for aged cancer patients.

Aged↗
PubMed1989

Alphoid satellite DNA is tightly associated with centromere antigens in human chromosomes throughout the cell cycle.

In this study, we have examined a DNA element specific to the centromere domain of human chromosomes. Purified HeLa chromosomes were digested with the restriction enzyme Sau3AI and fractionated by sedimentation through a sucrose gradient. Fractions showing antigenecity to anticentromere (kinetochore) serum obtained from a scleroderma CREST patient were used to construct a DNA library. From this library we found one clone which has specifically hybridized to the centromere domain of metaphase chromosomes using a biotinylated probe DNA and FITC-conjugated avidin. The clone contained a stretch of alphoid DNA dimer. To determine precisely the relative location of the alphoid DNA stretch and the centromere antigen, a method was developed to carry out in situ hybridization of DNA and indirect immunofluorescent staining of antigen on the same cell preparation. Using this method, we have found perfect overlapping of the alphoid DNA sites with the centromere antigen sites in both metaphase chromosomes and nuclei at various stages in the cell cycle. We have also observed this exact correlation at the attachment sites of artificially extended sister chromatids. These results suggest the possibility that alphoid DNA repeats are a key component of kinetochore structure.

Antigens↗
PubMed1989

A human centromere antigen (CENP-B) interacts with a short specific sequence in alphoid DNA, a human centromeric satellite.

We report the interaction between a human centromere antigen and an alphoid DNA, a human centromeric satellite DNA, which consists of 170-bp repeating units. A cloned alphoid DNA fragment incubated with a HeLa cell nuclear extract is selectively immunoprecipitated by the anticentromere sera from scleroderma patients. Immunoprecipitation of the DNA made by primer extension defines the 17-bp segment on the alphoid DNA that is required for formation of DNA-antigen complex. On the other hand, when proteins bound to the biotinylated alphoid DNA carrying the 17-bp motif are recovered by streptavidin agarose and immunoblotted, the 80-kD centromere antigen (CENP-B) is detected. DNA binding experiments for proteins immunoprecipitated with anticentromere serum, separated by gel electrophoresis, and transferred to a membrane strongly suggest that the 80-kD antigen specifically binds to the DNA fragment with the 17-bp motif. The 17-bp motif is termed the "CENP-B box." Alphoid monomers with the CENP-B box are found in all the known alphoid subclasses, with varying frequencies, except the one derived from the Y chromosome so far cloned. These results imply that the interaction of the 80-kD centromere antigen with the CENP-B box in the alphoid repeats may play some crucial role in the formation of specified structure and/or function of human centromere.

Autoantigens↗
PubMed1989

Application of chemical P450 model systems to studies on drug metabolism. I. Phencyclidine: a multi-functional model substrate.

Cytochrome P450 model and liver microsomal oxidations of drugs were compared using phencyclidine. In general, the chemical reaction systems produced many oxidation products. Besides the formation of the cyclohexane-4-hydroxyl compound (2), hydroxylation of the aromatic ring was favored in the Fenton reaction system (Fe2+ + H2O2). Formation of an m-hydroxylated product (m-5) was the main aromatic oxidation pathway in the Udenfriend reaction (Fe2+-ascorbic acid-O2), and 2, the piperidine-3-hydroxyl compound (3), and the piperidine-4-hydroxyl compound (4) were also formed. In the system using meso-tetraphenylporphinatoiron chloride (Fe(III)TPPC1) with an oxidant, the main product was the piperidine-3-oxo compound (8). In the liver microsomes system, 2, 4, 8, and m-5, which were all generated by the chemical oxidation reactions, were detected as metabolites of phencyclidine. They were formed by cytochrome P450-dependent reactions. Chemical oxidation systems can be used to study drug metabolism; they can reveal some tendencies of the real metabolic reactions, are easy to operate, and yield sufficient amounts of product.

Animals↗
PubMed1989

[Interstitial radiotherapy of carcinoma of the tongue-comparison between Jacobson-Yamamoto grading and prognosis].

One hundred and one patients of less than seventy years old with T1, T2 and N0 carcinoma of the tongue were graded according to the Jacobson-Yamamoto's grading (1-4 D). All patients were also classified into two groups such as less than fifty years old group and fifty to seventy years old group. Patients with grade 3, 4 C and 4 D carcinoma had more metastases to the cervical lymph nodes than grade 1, 2. Patients with T2N0 carcinoma showed approximately same five year cervical lymph node metastases free survival rate. However, the five year survival rate of less than fifty years old group was significantly lower than that of fifty to seventy years old group. In T2N0, grade 3-4 D carcinoma cases, more dead cases were found in less than fifty years old group than in fifty to seventy years old group.

Adult↗
PubMed1982

Role of unusually long common pancreatico-biliary channel as a cause of relapsing pancreatitis in children.

The article reports on two children with relapsing pancreatitis. In both cases operative cholangiogram demonstrated unusually long common pancreatico-biliary channel not associated with cystic dilatation of the common bile duct. The possibility and hypothetical mechanism that the long common pancreatico-biliary channel caused relapsing pancreatitis, are described. Exploratory laparotomy should be considered for children having recurrent abdominal pain with hyperamylasemia. For surgical treatment of this type of relapsing pancreatitis excision of the common bile duct and the gallbladder with hepatoenterostomy will be the best method.

Amylases↗