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Biomedical subjects

T Katsuki

Publications and source records attributed to T Katsuki.

At least 181 records · Page 10Linked to original sources
PubMed1979

Development of a solid-phase enzyme immunoassay for ursodeoxycholic acid: application to plasma disappearance of injected ursodeoxycholic acid in the rabbit.

A bile acid disappearance test using an enzyme immunoassay for ursodeoxycholic acid (UDCA) is presented. The immunoassay employs an antiserum produced in rabbits with UDCA coupled by amide linkage to egg albumin. An antigen (UDCA)-enzyme (beta-D-galactosidase) complex was prepared by adding the N-hydroxy-succinimide ester of UDCA to beta-D-galactosidase in a molar ratio of 5000:1. The anti-UDCA serum was coupled to glass beads and a competitive reaction between bile acids and UDCA coupled to the enzyme on the glass beads was measured by determining enzyme activity. One bead was used for each test tube. Thus it was convenient to wash and transfer the bead to a fresh test tube after incubation. The procedure requires 2.5 hr at 30 degrees C for the competitive reaction and enzyme assay. Using a 1:100 dilution of anti-serum, the intensity of fluorescence of 4-methylumbelliferone produced from 4-methylumbelliferyl-beta-D-galactoside by the enzyme decreased linearly with a logarithmic increase of UDCA concentration over a range of from 0.1 to 10 pmnd taurine conjugates, and good recovery data were obtained. The development of the enzyme immunoassay using glass beads shortens analysis time; furthermore, the method makes it possible to detect obstructive jaundice in rabbits before the serum bilirubin level is elevated.

Animals↗
PubMed1978

Colonies of EBNA-positive cells in soft agar from peripheral leukocytes of infectious mononucleosis patients.

Epstein-Barr virus (EBV)-associated nuclear antigen (EBNA)-positive lymphoblastoid cells grew as colonies in soft agar after seeding of leukocytes from the peripheral blood of four patients with infectious mononucleosis serologically determined to be caused by EBV. In individual cases more colonies were obtained from blood specimens during the acute phase of the disease than during the convalescent phase. Incorporation of human umbilical cord serum, which contained neutralizing antibody to EBV, into the agar medium did not reduce the number of colonies developing. Our observations indicate that colony-forming cells were originally present in the blood samples, and that they were not infected and subsequently transformed in vitro. Cells from less than 20% of the EBNA-positive colonies grew to form lymphoblastoid cell lines, which were EBNA-positive and had B lymphocyte surface markers. However, the majority (over 80%) of the EBNA-positive colonies failed to form immortalized cell lines. No colonies were obtained from 91 blood samples from healthy young adults and from five patients with an IM-like disease unrelated to EBV infections. The present results strongly suggest that already transformed cells or cells very easily transformed by EBV are present in the blood of IM patients.

Adult↗
PubMed1978

A convenient method of establishing permanent lines of xeroderma pigmentosum cells.

Nine lymphoblastoid cell lines were established after transformation by Epstein-Barr virus of peripheral lymphocytes from four xeroderma pigmentosum (XP) patients, the parents of one XP patient, and three normal donors. All these cell lines proliferate as suspension in Roswell Park Memorial Institute Medium 1640 supplemented with 20% fetal bovine serum, without detectable release of infectious Epstein-Barr virus. Some characteristics of these cell lines, such as growth rates, chromosome numbers, UV sensitivities, and activities of unscheduled DNA syntheses induced by UV, 4-nitroquinoline 1-oxide, and N-methyl-N'-nitro-N-nitrosoguanidine, were determined. Results confirm that the properties related to XP are not altered by transformation with Epstein-Barr virus and are the same in degrees of defect as are those of dermal fibroblasts from the respective individuals. These XP and normal lymphoblastoid cell lines should be especially useful for biochemical studies on the mechanism of DNA repair, because they are easy to grow in mass culture.

Autoradiography↗
PubMed1976

A quantitative analysis of the susceptibility of human leukocytes to transformation by Epstein-Barr virus.

Susceptibility of lymphocyte-enriched cell fractions isolated from human umbilical cord blood and adult peripheral blood to transformation by the B95-8 strain of Epstein-Barr virus (EBV) was investigated quantitatively. Minimum multiplicity of input of virus (50% transforming dose) per cell (MOI) necessary to induce maximum level transformation of cord cells ranged from 0.02 to 0.2. The frequency of initially transformed cells (fraction of transformable cells) in the cord cell samples from two different individuals was estimated to be 2.6 to 6.2%. In this system, the appearance of cells positive for EBV-associated nuclear antigen (EBNA) paralleled the growth curve of transformed cells. About 70% of the latter were EBNA-positive. In adult cell preparations from two individuals, 1.8 and 0.03%, respectively, of the cells were transformable indicating larger individual variations in sensitivity to EBV than in cord cells. The EBV susceptibility was also determined by the transforming efficiency (TE) expressed as the negative log of the virus dilution which induces transformation in 50% of cell cultures infected at an MOI of 0.2. From the TE value, a minimum MOI which induces transfromation could be calculated. Also by this test it was shown that the EBV susceptibility of adult cells was not only lower but also much more variable between individuals than that of cord cells. There was no correlation between the susceptibility of cells and the titer of anti-EBV antibody in donors' sera. In cultures of mixed cord cells and adult cells known to have low EBV susceptibility, the minimum MOI increased in proportion to the amount of adult cells.

Adult↗
PubMed1976

Cell-killing by Epstein-Barr virus: analysis by colony inhibition procedure.

The P3HR-1 and B95-8 strains of Epstein-Barr virus (EBV) were cytocidal for EBV-carrier human cell lines, as revealed by a colony inhibition procedure. The cytocidal activity was proportional to virus dose added. The cell killing was neutralized by anti-EBV antibody-positive but not -negative human sera. When the relative sensitivity to ultraviolet light of EBV activities was examined, the cytocidal actitivy was much more resistant than the viral infectivity as assayed by early antigen-forming activity (P3HR-1 virus) or leukocyte-transforming activity (B95-8 virus), but it closely paralleled the ability to adsorb to cells.

Adsorption↗
PubMed1976

Transformation of tonsil lymphocytes by Epstein-Barr virus.

Tonsil lymphocytes obtained from children and adults at tonsillectomy were examined for susceptibility to infection with Epstein-Barr virus (EBV) in vitro. Of 37 specimens, 24 (65%) were transformed by EBV. Rate of transformation was higher in the cells from younger children than in those from older children and adults, but the susceptibility was not directly correlated to the titer of antibody against EBV in donor serum. All 22 transformed tonsil cell lines tested were carrying EBV-associated nuclear antigen, and 8 of them produced cytoplasmic IgA in 15-45% of cells. The results suggest that tonsil lymphocytes are targets of EBV.

Antibodies, Viral↗
PubMed1975

Characteristics of cell lines derived from human leukocytes transformed by different strains of Epstein-Barr virus.

Variation of Epstein-Barr virus (EBV) in respect to its effect on the properties of transformed cells was probed. Human umbilical cord leukocytes from six different individuals were transformed in vitro by either B95-8 (B) or QIMR-WIL (Q) strains of EBV and subsequently 12 lymphoblastoid cell lines (six B-derived and six Q-derived lines) were established. The B lines and Q lines were different in the expression of EBV genome i.e. production of virus or viral antigens, and in other properties including growth pattern and immunoglobulin production. The most striking differences between the two groups lay in their capacity to produce infectious virus and in the shape of the cell-clumps. The results suggest that different strains of EBV may induce transformed cells with different characteristics.

Antigen-Antibody Reactions↗