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Biomedical subjects

S Iwasa

Publications and source records attributed to S Iwasa.

At least 73 records · Page 4Linked to original sources
PubMed1989

The pyrogenicity of pertussis vaccine in mice and the factors in the vaccine responsible for this effect.

The injection of whole cell pertussis vaccine into mice produced a biphasic fever reaction with two peaks appearing after about one and four hours, respectively. A method for the quantitative determination of each peak fever activity was developed and the factor responsible for each activity was investigated. The first and the second peak fever activities did not parallel each other in individual vaccines. The earlier fever activity appeared to correlate with endotoxin activity in individual vaccines while the later appeared to correlate with histamine-sensitizing factor (HSF) activity. The later peak fever activity was greatly reduced by heating the vaccine at 100 degrees C for 30 min while the first was little affected by such treatment. It was concluded that the fever activity of pertussis vaccine in mice may be ascribed to the combined actions of endotoxin and a heat-labile substance, possibly HSF.

Animals↗
PubMed1989

The quantitative assay of the clustering activity of the lymphocytosis-promoting factor (pertussis toxin) of Bordetella pertussis on Chinese hamster ovary (CHO) cells.

An experimental design and a statistical method for the estimation of the clustering-response activity of lymphocytosis-promoting factor (LPF) in Chinese hamster ovary cells growing in wells on a microplate were investigated. The scoring method introduced by Ipsen was adopted to express the grade of the clustering response rather than the end-point method generally used. The scoring method was validated by statistical analyses. The grade of response varied with the location of the wells on a microplate, and thus the expression of the clustering activity of a test sample in terms of the end-point may be inadequate in terms of accuracy and reproducibility. It was shown that the allocation of test samples to individual wells according to a Latin square design minimized the effect of the location of wells on the clustering response. Under such experimental conditions, a fairly precise and reproducible method for the quantification of the clustering activity was developed.

Animals↗
PubMed1989

An enzyme immunoassay for human lymphotoxin.

A highly sensitive and specific enzyme immunoassay (EIA) for human lymphotoxin (hLT) has been developed. The assay is based upon a sandwich system employing two kinds of anti-hLT antibodies with neutralizing activity. One of them was mouse monoclonal antibody raised against Escherichia coli-derived recombinant hLT with a deletion of 20 amino-terminal amino acids and used as labelled antibody. The other was rabbit antibody raised against the carboxyl-terminal portion of hLT and used as solid-phase antibody. The EIA employing such a combination was able to detect less than 50 pg/ml of hLT, showing that this method was approximately 5-10 times higher sensitivity than the conventional bioassay employing L929 cell-lysis. The mean recovery of hLT added to serum specimens was 101% and the coefficients of variation were 3.3-7.8% (intra-assay) and 2.9-17.2% (interassay). There was a good correlation between the present EIA and the bioassay (r = 0.93).

Animals↗
PubMed1989

Bispecific antibody-producing hybrid hybridoma and its use in one-step immunoassays for human lymphotoxin.

A hybrid hybridoma cell line secreting a bispecific monoclonal antibody (MAb) was constructed by fusing horseradish peroxidase (HRPO)-immunized mouse splenocytes with previously established mouse hybridomas secreting anti-human lymphotoxin (hLT). This cell line was grown in ascitic fluid in mice to obtain large quantities of hybrid MAbs and a bispecific antibody, reacting with both HRPO and hLT, was separated from the monospecific antibody or other inactive immunoglobulin populations by hydroxylapatite chromatography. Sodium dodecylsulfate-polyacrylamide gel electrophoresis demonstrated that the bispecific antibody molecule contained two different types of heavy and light chains of both anti-HRPO and anti-hLT origin. The bispecific antibody was used to establish one-step enzyme immunoassays (EIAs) employing competitive and sandwich systems. The simple sandwich EIA was able to detect 1-100 U/ml of hLT and there was good correlation (r = 0.96) between hLT concentrations measured by the one-step EIA and a bioassay using L929 cell-lysis.

Antibodies, Monoclonal↗
PubMed1989

A human monoclonal antibody recognizing a surface antigen on stomach cancer cells.

Lymph-node lymphocytes of a patient with stomach cancer were fused with the mouse-human heterohybridoma, HM-5. A clone (2F9) was isolated that showed stable production of an IgM antibody reactive with NUGC-4 stomach cancer cell line. This antibody reacted predominantly with a cell surface antigen on cell lines originating from gastro-intestinal cancer and adenocarcinoma of lung, whereas it was not generally reactive with other types of cancers, or with normal kidney cells or fibroblasts. Biotin-labeled 2F9 antibody clearly stained cell smears and the nude mouse tumor of NUGC-4, but it did not show a positive reaction with stomach cancer tissues obtained from more than 10 patients, indicating that the antigen detected is very weakly expressed on tumor cells or on a limited number of stomach cancers. The antigen shed from NUGC-4 cell line was detected in the culture supernatant. 2F9 antibody precipitated a glycoprotein with a molecular weight of over 200 kilodaltons as well as a possible glycolipid, from NUGC-4 cells labeled with [3H]glucosamine or [35S]-H2SO4. Periodic acid treatment of the tissue section decreased reactivity with 2F9 antibody, but heat, neuraminidase or protease treatment did not. These results suggested that the epitope is present on a carbohydrate moiety not containing sialic acid, and that a part of the antigen molecule is sulfated.

Animals↗
PubMed1989

Cobalamin-dependent replication of L1210 leukemia cells and effects of cobalamin analogues.

L1210 cell line cells were made deficient in Cbl by propagation in a medium devoid of CNCbl in which fetal calf serum had been replaced by bovine serum albumin. These Cbl-deficient cells gradually ceased to multiply when the medium contained 5-CH3THF, although cell growth was resumed following the addition of CNCbl, OHCbl or folic acid. The results of this study provide experimental proof for the 'methyl trap' hypothesis. In contrast to the above effect of CNCbl, cobinamide and Cbl analogues which were produced by a reaction of OHCbl with ascorbic acid did not have any growth-inducing effect on the cells which had been cultured in a 5-CH3THF-supplemented medium and had ceased to multiply. Nor did these analogues have an inhibitory effect on CNCbl-dependent growth.

Animals↗
PubMed1988

Effect of methotrexate on the deoxyuridine suppression test: results with different cell preparations.

Recently, the deoxyuridine suppression test was used to detect folate deficiency. Several cell preparations were used in this test, and the sensitivity of the test seems to vary with them. We used whole blood (micro-dU test) and bone marrow cells for the deoxyuridine suppression test, and the effects of methotrexate were compared. [3H]Thymidine incorporation into DNA was highest when the concentration of methotrexate was 1 microM in the whole blood culture and bone marrow culture. Methotrexate concentrations from 100 nM to 1 mM did not affect the results of the micro-dU test. However, the bone marrow deoxyuridine test became abnormal with methotrexate, and the abnormality in test values was corrected by the addition of N5-formyltetrahydrofolate. Differences in the results between the micro-dU test and the bone marrow deoxyuridine suppression test seem to represent specificity of each dU test.

Bone Marrow↗
PubMed1986

Binding of cobalamin analogs to intrinsic factor-cobalamin receptor and its prevention by R binder.

It is now known that nonphysiological cobalamin analogs exist in the gastrointestinal tract, but their metabolic behavior is unclear. In this study, [57Co]cobinamide was used to study its affinity to hog intrinsic factor-cobalamin (IF-Cbl) receptor which has no species specificity against human IF-Cbl receptor, and its relation to human saliva R binder. Cobinamide was prepared from [57Co]cyanocobalamin and separated by paper chromatography. Human IF-Cbl complex was bound to IF-Cbl receptor but free cyanocobalamin was not. Although R binder-cobinamide was not bound to the IF-Cbl receptor, free cobinamide was bound to the IF-Cbl receptor to a significant extent (about one-half of IF-cyanocobalamin binding to the IF-Cbl receptor). We then investigated the binding of cobinamide to R binder and trypsin-treated R binder. Association constant of cobinamide binding to the IF-Cbl receptor was 1.0 X 10(9) M-1 which was much lower than that of cobinamide binding to trypsin-treated R binder and to untreated R binder. Further study indicated that cobinamide binding to the IF-Cbl receptor was blocked by the addition of R binder and also by trypsin-treated R binder. We conclude that one of the roles of R binder is to prevent binding of free cobalamin analogs to the IF-Cbl receptor in the gut.

Cobamides↗
PubMed1985

Swelling of the brain in mice caused by pertussis vaccine--its quantitative determination and the responsible factors in the vaccine.

Intracerebral injection of vaccine into the mouse induced swelling of the brain. The swelling reached the maximum in the intensity by day 1 and persisted for several days. A method for quantitative determination of the brain-swelling activity of the vaccine was developed. A positive regression coefficient was found only between the brain-swelling and the lymphocytosis-promoting activities. Such activity was no longer shown with the vaccine heat-treated for 30 min at 80 C, but it was restored upon addition of the lymphocytosis-promoting factor (LPF) that caused no brain swelling by itself. The activity, therefore, was ascribed to cooperation of LPF and a certain heat-stable component other than endotoxin contained by pertussis vaccine.

Animals↗
PubMed1985

A curious histamine-sensitizing activity shown by the newly-developed Japanese acellular pertussis vaccine.

A new acellular pertussis vaccine, whose official name is "Precipitated Purified Pertussis Vaccine" (PPV), was prescribed in the Japanese Minimum Requirements for Biological Products in 1981. The PPV is composed of partially detoxified fractions of pertussis cells. The histamine-sensitizing (HS) activities of PPV vaccines are less than those of killed whole pertussis cell vaccines (WPV) produced in Japan until 1980, when the histamine challenge was carried out in mice on day four after injection. It was found that when the histamine challenge day was delayed that the HS activities of some lots of PPV gradually increased from those estimated on day four after injection of PPV and reached the maximum in about 12 days, while the activity of the reference whole cell pertussis vaccine reached the maximum several days after injection and then gradually decreased. Hereafter, HS activities of test materials estimated on days four and 12 after injection are referred to as early HS (EHS) and late HS (LHS) activities, respectively. Since LHS activity of the reference whole cell vaccine is lower than its EHS activity and the reverse is true with many lots of PPV, it is often observed that the EHS activity of PPV according to the Japanese requirement for PPV, ranges from 0.02 to 2.0 HSU whereas activities of some lots of PPV were estimated at 5.0 to 25.0 HSU. The relationship of the detoxifying process to EHS and LHS activities was studied with bulk materials, which were used for the purification procedure but prior to the detoxification process for the production of PPV.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗