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Biomedical subjects

C Nakayama

Publications and source records attributed to C Nakayama.

At least 55 records · Page 3Linked to original sources
PubMed1986

99mTc-methylene diphosphonate uptake by ossifications and calcifications of non-osseous metastatic tumors.

Two cases of extra-osseous uptake of 99mTc-methylene diphosphonate (MDP) by non-osseous metastatic tumors are reported. One was a metastasis with ossification in the abdominal wall from carcinoma of the sigmoid colon and the other was a metastasis with calcification from an ovarian carcinoma. The mechanism of extra-osseous uptake of 99mTc-MDP is discussed. Bone scintigraphy can be a potential means to assess tumor spread with ossifications and calcifications.

Abdominal Neoplasms↗
PubMed1986

Computed tomography for preoperative evaluations of lung cancer.

Computed tomography was evaluated for its accuracy in diagnosing mediastinal node metastases, direct chest wall invasion, and direct mediastinal invasion by lung cancer among 61 patients who subsequently underwent surgery. Using 15-mm diameter or larger mediastinal lymph nodes as the criterion for metastasis, the sensitivity was 36% (8/22); the specificity was 92% (34/37). The accuracy for direct chest wall invasion was relatively high, with a sensitivity of 100% (7/7) and a specificity of 92% (22/24). Direct mediastinal invasion had a sensitivity of 67% (4/6) and a specificity of 91% (10/11). These results suggest that the ability of computed tomography to diagnose mediastinal lymph node metastasis when such nodal size is used as a criterion is limited.

Humans↗
PubMed1986

A case of anomalous origin of the right coronary artery from the left sinus of Valsalva exhibiting the Wolff-Parkinson-White syndrome.

A 56-year-old male with the Wolff-Parkinson-White syndrome was suspected of having suffered a myocardial infarction following attacks of chest pain. Serial measurements of serum creatine phosphokinase and the electrocardiographic findings after ajmaline loading virtually excluded the possibility of myocardial infarction. Paroxysmal tachycardia was not noted on 24 Holter electrocardiographic monitoring. Both the left and right coronary arteries were found by selective coronary angiography to originate from the left sinus of Valsalva, but neither of the arteries showed organic stenoses. However, myocardial 201Tl scintigraphy after exercise indicated poor uptake in the high anterolateral wall, and at the apex and septum near the anterior wall, which suggested the absence of ischaemia in the area supplied by the right coronary artery. We speculate that a left coronary artery steal phenomenon was the cause of the ischaemia after exercise in this patient.

Aortography↗
PubMed1986

[Enzyme immunoassay and radioimmunoassay using monoclonal antibody for the determination of estrogen receptors in human breast cancer].

Enzymeimmunoassay (EIA) with monoclonal antibody against human estrogen receptor (ER) from MCF-7 breast cancer cells and radioimmunoassay (RIA) with monoclonal antibody against ER D-5 antigen from human myometrium were applied to human breast tumor, and the results were compared to those of steroid binding assay using the dextran coated charcoal (DCC) method. The rates of coincidence of positivity and negativity of ER between the DCC method and EIA or RIA in 30 human breast tumors were 96.7% (29/30) and 86.7% (26/30), respectively. A highly significant positive correlation was observed between ER values obtained by the DCC method and those by EIA (r = 0.87, P less than 0.001). On the other hand, the correlation between ER values obtained by the DCC method and those by RIA was less significant (r = 0.41, P less than 0.05). The discrepancy between these ER values may be due to the difference of the monoclonal antibody used in each new assay. The above results indicate that EIA and RIA with monoclonal antibody for human ER are useful for clinical use, although the reason for the partial discrepancy of the data between the DCC method and RIA remains to be elucidated.

Antibodies, Monoclonal↗
PubMed1985

Computed tomography characterization of anterior mediastinal tumors.

The computed tomography manifestations of 39 patients with histologically proved anterior mediastinal tumors were studied by categorizing the tumors by content as solid homogeneous, cystic homogeneous, and heterogeneous. Among 24 solid tumors, thymomas were easily distinguished by their lack of invasiveness from malignant lymphomas and germ-cell tumors. Among 11 cystic tumors, pericardial and thymic cysts were differentiated from cystic teratomas and bronchogenic cysts by their lack of recognizable capsules with or without calcification. The differential diagnosis of a variety of tumors of the anterior mediastinum was facilitated by computed tomography in all but a few exceptional cases.

Adolescent↗
PubMed1985

Inhibitory effects of 9-beta-D-xylofuranosyladenine 5'-triphosphate on DNA-dependent RNA polymerase I and II from cherry salmon (Oncorhynchus masou).

In order to determine the mode of action of cytostatic 9-beta-D-xylofuranosyladenine (xylo-A), the inhibitory effects of 9-beta-D-xylofuranosyladenine 5'-triphosphate (xylo-ATP) on DNA-dependent RNA polymerases I and II purified from cherry salmon (Oncorhynchus masou) liver nuclei were studied. This nucleotide showed strong inhibitory action on both RNA polymerases I and II. The K1 values are 14 microM for polymerase I and 5 microM for polymerase II (Km values of ATP are 37 microM for polymerase I and 40 microM for polymerase II). The mode of xylo-ATP was competitive with respect to the incorporation of AMP into RNA and non-competitive to UTP and CTP.

Adenosine Triphosphate↗
PubMed1985

Differential inhibitory effects of 5-substituted 1-beta-D-xylofuranosyluracil 5'-triphosphates and related nucleotides on DNA-dependent RNA polymerases I and II from the cherry salmon (Oncorhynchus masou).

Various 5-substituted 1-beta-D-xylofuranosyluracil 5'-triphosphates (hydrogen, methyl-, ethyl-, n-propyl, n-butyl, fluoro-, chloro-, bromo-, and iodo derivatives) and some of the 3'-deoxyribofuranosyl nucleotides (3'-deoxy UTP and 3'-deoxy TTP) were synthesized chemically and their inhibitory effects on DNA-dependent RNA polymerases I and II of the cherry salmon (Oncorhynchus masou) were studied systematically. These 3'-modified UTP analogues could not be utilized as substrates in place of UTP, but they did inhibit the incorporation of UMP into RNA in vitro. In contrast, 2'-modified UTP analogues, such as 2'-dTTP and Ara TTP, were neither substrates nor inhibitors. Kinetic analysis showed that the inhibition by these compounds was essentially competitive with substrate UTP. The K1 values of RNA polymerase I for the analogues were smaller (2-6 microM) than the Km value for UTP (8 microM), but those for xylo-EtUTP, xylo-PrUTP, and xylo-BuUTP were larger (about 20 microM) than the Km for UTP. In contrast to these alkyl groups with steric and electron-donating effects, halogen groups have electron-withdrawing effects on the uracil nucleus. Therefore, it was concluded that the inhibitory activity of these analogues on RNA polymerase I was not affected by the inductive effects of substituent groups at the 5-position of uracil nucleus but by their steric effects. On the other hand, all of the K1 values of RNA polymerase II for UTP analogues were smaller (0.4-3 microM) than the Km value for UTP (4 microM). In this case, neither steric effect nor an inductive effect of substituents on UTP analogues influenced the inhibitory activity towards RNA polymerase II.

Animals↗
PubMed1985

Mechanism of selective inhibition of human cytomegalovirus replication by 1-beta-D-arabinofuranosyl-5-fluorouracil.

Four kinds of 1-beta-D-arabinofuranosyl-5-halogenouracil were examined for inhibition of human cytomegalovirus (HCMV) and herpes simplex virus type 1 (HSV-1) and 2 (HSV-2) replication. 1-beta-D-Arabinofuranosyl-5-fluorouracil (ara-FU) was the most effective against HCMV, whereas 1-beta-D-arabinofuranosyl-5-bromouracil was the most effective against HSV-1 and HSV-2. The mechanism of action of ara-FU on HCMV replication was also studied. The dTTP pool size in human embryonic fibroblasts was increased 33-fold by HCMV infection. However, treatment with ara-FU decreased the size of the dTTP pool by approximately 50%. On the other hand, 1-beta-D-arabinofuranosyl-5-fluorouracil-5'-triphosphate inhibited HCMV DNA polymerase activity competitively with dTTP. These results suggest that ara-FU acts as a bifunctional inhibitor of HCMV replication. Ara-FU is phosphorylated by cellular thymidine kinase to 1-beta-D-arabinofuranosyl-5-fluorouracil-5'-monophosphate, which inhibits cellular thymidylate synthetase, which in turn decreases the dTTP pool size in infected cells. As the dTTP pool size is reduced, inhibition of viral DNA polymerase by 1-beta-D-arabinofuranosyl-5-fluorouracil-5'-triphosphate becomes more efficient.

Antiviral Agents↗
PubMed1984

Utilizations of various uridine 5'-triphosphate analogues by DNA-dependent RNA polymerases I and II purified from liver nuclei of the cherry salmon (Oncorhynchus masou).

Various 5-substituted UTPs (methyl, ethyl, n-propyl, n-butyl, fluoro, chloro, bromo, and iodo) and sulfur-containing UTP analogues (4-thio-, 2-thio-, 5-methyl-2-thio-, and 5-methyl-4-thio-) were synthesized chemically and their utilization by DNA-dependent-RNA polymerases I and II of the cherry salmon (Oncorhynchus masou) were studied in substitution experiments under the condition of limited RNA synthesis in vitro. RNA polymerase I utilized the 5-methyl-, chloro, bromo, and iodo derivatives of UTP more efficiently than unmodified UTP, but RNA polymerase II utilized UTP most efficiently. 5-Methyl-4-thiouridine 5'-triphosphate (4-thio TTP) was utilized more efficiently than UTP by RNA polymerase I. On the other hand, it was found that 4-thio TTP was a selective substrate for RNA polymerase I and that its incorporation by RNA polymerase II was very slow. Thus recognition of UTP analogues as substrates by RNA polymerase I and II was different. These observation were attributed from kinetic analyses to differences in catalytic activity (Vmax).

Animals↗
PubMed1983

[Bone mineral measurement using beam scanner with a single source of 241Am].

The feasibility of a bone mineral analyzer equipped with a single source of 241Am but with a specially designed water bath (Beam Scanner, Aloca Co. Ltd.) was evaluated both experimentally and clinically. The attenuation rate of 241Am gamma-ray showed an exponential decrease with the increase of the thickness of the plaster plate containing CaSO4. Measurements of the test tubes filled with Ca(OH)2 demonstrated the measured mineral values to be in good correlation with the amount of Ca(OH)2. The coefficient of variation (C.V.) of bone mineral values obtained by measuring the phantom 20 times was 4.06%. Reproducibility tests performed in 10 normal persons after an interval of 8 months revealed a C.V. of 2.0%. Bone mineral values seemed to reach their peak in the 4th decade and thereafter gradually decreased with aging in normal persons. A marked decrease of the bone mineral value was observed in 5 cases of osteoporosis. We conclude that the bone mineral measurement using the above described method is practical and reliable.

Adult↗