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Biomedical subjects

Y Saeki

Publications and source records attributed to Y Saeki.

At least 235 records · Page 13Linked to original sources
PubMed1984

Dissociation in the production of B cell-stimulating factors (BCGF and BCDF) and interleukin 2 by T cells from a common variable immunodeficient patient.

In the course of an analysis of lymphocyte functions of common variable immunodeficiency patients, we found one patient whose T lymphocytes released B cell differentiation factor (BCDF) and B cell growth factor (BCGF) without IL 2 production upon stimulation with Con A. The patient was a 68-yr-old woman with hypo-gamma-globulinemia (IgM: 31 mg/dl, IgG: 223 mg/dl, IgA: 23 mg/dl); she suffered from cryptococcal meningitis and pulmonary tuberculosis with a negative result of skin tests to PPD and cryptococcal antigen. The number of T cells and the ratio of T cell subsets (Leu-2a and Leu-3a) was normal. T cells showed no proliferative response to Con A and a low response to PHA (one-tenth of normal response). The addition of patient T cells to normal T cells did not inhibit the proliferation of normal T cells when stimulated by Con A. The culture supernatant of Con A-stimulated T cells contained no IL 2 activity when assayed by an IL 2-dependent T cell line. Expression of Tac antigen was not impaired by Con A stimulation and the addition of partially purified IL 2 from the supernatant of Jurkat T cell line-induced proliferation of Con A-stimulated T cells, indicating that the defect observed was not in IL 2-responding cells but in IL 2-producing cells. In contrast, the culture supernatant of the T cells stimulated by Con A or PHA contained BCDF activity as much as that of normal T cells when assayed by Cowan I-stimulated normal B cells or the B lymphoblastoid cell line SKW6-CL4. The supernatant also contained BCGF activity. These results suggest that B cell-stimulating factor (BCGF, BCDF) and IL 2 may be synthesized by different subsets of T cells or that the synthesis of those lymphokines are independently regulated in the same cells.

Adult↗
PubMed1984

[Regression of adenomas in Gardner's syndrome induced by systemic chemotherapy].

A 31-year-old male was admitted to our hospital with Gardner's syndrome and sigmoid colon cancer. Palliative resection (sigmoid colectomy) was performed due to hepatic and lymph node metastasis. Systemic chemotherapy with MMC, 5-FU and PSK was started postoperatively. Barium enema study on the 23rd successive post-operative day and fiberscopic study on the 134th post-operative day showed regression of the size and number of the polyps in the remaining colon and rectum. We suggest that the administration of anticancer drugs may be useful in the treatment of familial polyposis or Gardner's syndrome which have been treated with only surgical therapy.

Adenoma↗
PubMed1983

Crystallization and properties of aromatic amine dehydrogenase from Pseudomonas sp.

An amine dehydrogenase was purified to homogeneity from an extract of a bacterium of the genus Pseudomonas grown in a medium containing beta-phenylethylamine as a sole carbon source and obtained in a crystalline form with about 100-fold purification. The purified enzyme catalyzed the oxidative deamination of various aromatic amines as well as some aliphatic amines to a lesser extent. An artificial electron acceptor such as phenazine methosulfate was required for the catalysis. The molecular weight determined by sedimentation equilibrium was 103,000 and the molecule seemed to be composed of two pairs of two nonidentical subunits (Mr 46,000 and 8000). The enzyme had a dull yellow-green color with an absorption maximum at 445 nm and this chromophore appeared to be involved in the catalytic action of the enzyme.

Amino Acids↗
PubMed1983

[Dioxygenases].

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4-Hydroxyphenylpyruvate Dioxygenase↗
PubMed1982

Effects of cholesterol evulsion on susceptibility to perfringolysin O of human erythrocytes.

Human erythrocytes preincubated with a phosphatidylcholine suspension (preincubated cells) showed decreased susceptibility to perfringolysin O, the decrease being strongly affected by preincubation time and temperature, and the phosphatidyl choline concentration. The binding of the toxin to the preincubated cells also decreased with the preincubation time and reached minimum at 37 degrees C for 6 h. Through this preincubation, about 30% of cholesterol was removed from cells without lysis. The susceptibility of preincubated cells to the toxin seemed to be affected by the amount of cholesterol removed from cells, but not by the cholesterol content of cell membranes. This indicates that most of the cholesterol interactive with the toxin is removable from cell membranes by preincubation with phosphatidylcholine suspension, and that the residual cholesterol is firmly constituted in the membrane structure and cannot interact with the toxin. After cholesterol evulsion by the preincubated plasma method (Murphy, J.R. (1962) J. Lab. Clin. Med. 60, 86-109 and 60, 571-578), cells also exhibited lower susceptibility to the toxin and to saponins, but higher susceptibility to lysophosphatidylcholine.

Bacterial Toxins↗
PubMed1982

[Enzymic determination of dipalmitoylphosphatidylcholine in human amnionic fluid--its application for the judgement of fetal lung maturity before birth (author's transl)].

Respiratory distress syndrome (RDS) is believed to be caused by a deficiency of pulmonary surfactant. The surfactant, secreted by fetal lung into amnionic fluid, has been analyzed by a variety of methods, but none of these methods have been found accurate enough to be widely used. Dipalmitoylphosphatidylcholine (DP-PC), the major surface-active component of the surfactant, occupies more than 50% of the surfactant phospholipids. In this study, DP-PC isolated from amnionic fluid, was determined enzymatically. DP-PC started to increase gradually in amnionic fluid from 22nd week of gestation, showed rather rapid increase after 35th week of pregnancy, and reached to a value of 6.97 +/- 0.56 mg/dl (Mean +/- SEM, n = 117) between 38 and 42nd week of gestation. This increase of DP-PC during gestation was found to be quite similar to that of L/S ratio reported previously. Eight out of 10 infants with RDS had less than 1.0 mg/dl of DP-PC in the amnionic fluid, whereas 137 infants without any sign of RDS had more than 1.0 mg/dl of DP-PC except 5 cases. These results demonstrated that if more than 1.0 mg/dl of DP-PC was found in amnionic fluid before birth, the fetus could be judged to have mature lung with 96% accuracy. In addition the enzymic determination of DP-PC requires less time, rather easy and reliable method to be done in most general clinical laboratories with less cost. Therefore we believe this method will be widely used in near future for the detection of RDS before birth.

Amniotic Fluid↗
PubMed1981

Excitation-contraction coupling in mammalian cardiac muscle during Ba2+-induced contracture.

The membrane potential and tension were recorded during contracture of mammalian ventricular muscles bathed in Tyrode solution with Ba2+ in the place of Ca2+. Strength of contracture increased with increasing Ba2+ concentration from 0.1 to 4 mM and reached a plateau above 4 mM. The membrane potential was depolarized to about -35 mV with 0.1 mM Ba2+ and to -20 mV with 5 mM Ba2+. When 0.5 mM Mn2+ was added to Ba2+-Tyrode solution, in which the muscle had been in a state of steady contracture, the muscle immediately started to relax to the resting level. In contrast, addition of 2 micrograms/ml epinephrine to Ba2+-Tyrode solution increased the strength of the contracture. Neither epinephrine nor Mn2+ caused any noticeable changes of the depolarized membrane potential. The results suggest that Ba2+ not only activates the contractile system but also depolarizes the membrane potential independently of activating the contractile system. These two remarkable actions of Ba2+ seem to be responsible for the long-lasting contracture.

Action Potentials↗
PubMed1980

Cleavage of pyrogallol by non-heme iron-containing dioxygenases.

Both intradiol and proximal extradiol dioxygenases are thought to produce the same product, alpha-hydroxymuconic acid, when pyrogallol (3-hydroxycatechol) is used as a substrate. However, when these enzymes were reacted with pyrogallol, they gave different products. A proximal extradiol dioxygenase, metapyrocatechase (catechol:oxygen 2,3-d-oxidoreductase (decyclizing), EC 1.13.11.2), gave a product having an absorption maximum at 290 nm, which was gradually converted to a more stable compound having an absorption maximum at 239 nm. On the other hand, an intradiol dioxygenase, protocatechuate 3,4-dioxygenase (protocatechuate:oxygen 3,4-oxidoreductase (decyclizing), EC 1.13.11.3), gave a product having an absorption maximum at 300 nm. Based on the spectral data and direct comparison with authentic samples, the primary products obtained by the action of the former and the latter enzymes were identified as alpha-hydroxymuconic acid and 2-pyrone-6-carboxylic acid, respectively. While another intradiol dioxygenase, pyrocatechase (catechol:oxygen 1,2-oxidoreductase (decyclizing), EC 1.13.11.1), gave a mixture of nearly equimolar amounts of these two compounds. Isotope labeling experiments indicated that 1 atom of oxygen was incorporated in 2-pyrone-6-carboxylic acid from the atmosphere. Based on these findings, the reaction mechanism for the formation of 2-pyrone-6-carboxylic acid is discussed. This may be the first experimental evidence indicating the presence of a seven-membered lactone intermediate during the oxygenative cleavage of catechols, proposed by Hamilton (Hamilton, G.A. (1974) in Molecular Mechanisms of Oxygen Activation (Hayaishi, O., ed) pp. 405-451, Academic Press, New York).

Catechol 2,3-Dioxygenase↗