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Biomedical subjects

S Iwasa

Publications and source records attributed to S Iwasa.

13 recordsLinked to original sources
PubMed1979

Enzyme immunoassay of pancreatic glucagon at the picogram level using beta-D-galactosidase as a label.

An enzyme immunoassay of pancreatic glucagon was established by using E. coli beta-D-galactosidease [EC 3.2.1.23] as a marker. In order to increase the sensitivity of the immunoassay, different peptides obtained from glucagon fragments were used to produce the enzyme conjugate and the immunogen. Antiserum N6E raised against C-terminal fragment peptide (15-29) could be diluted to more than 1 : 100,000 in the assay and was highly specific for pancreatic glucagon. The antiserum reacted well with the C-terminal fragment peptide (21-29) as well as another fragment peptide (15-29) and pancreatic glucagon. The enzyme immunoassay using antiserum N6E and fragment peptide (21-29)-enzyme conjugate could detect as little as 1 to 2 pg of glucagon. The mean recovery of glucagon added to serum specimens was 104% and the coefficients of variation were 3.7-14.5% (within assay) and 9.0-18.5% (between assay).

Escherichia coli↗
PubMed1979

Multicorrelation analyses of toxic and antigenic components of DPT and DP vaccines produced in Japan.

The combined diphtheria-pertussis-tetanus and combined diphtheria-pertussis vaccines, of which the contents of endotoxin, LPF and HSF were reported in the previous paper, have been tested for the respective potencies of pertussis, diphtheria and tetanus components. In order to obtain some information concerning possible adjuvanticities of the toxic components of pertussis cells, relationship between respective toxic activities and the potencies of the respective antigenic components were tested by applying the multiple regression analyses. The results showed that the effects of the toxic components were fairly complicated. Within the ranges of contents of the respective toxic components of the vaccines used in the present experiment, LPF appeared to enhance all the three potencies as the content increased, while the effects of endotoxin and HSF were either enhancing or suppressive depending on the antigenic components.

Antigens, Bacterial↗
PubMed1978

Enzyme immunoassay of a beta-adrenergic agent using beta-galactosidase as label.

Antisera against tetrahydronaphthalenols, which are conformationally rigid derivatives of adrenergic catecholamine, were produced in rabbits immunized with trans-5-amino-6-hydroxy-2-isopropylamino-1,2,3,4-tetrahydronaphthalene-1 -ol (I) conjugated to succinylated bovine serum albumin at the C5 position on the tetralin ring. Antisera were screened by immunodiffusion and further characterized by passive hemagglutination assay using erythrocytes sensitized with trans-I-ovalbumin conjugate and by enzyme immunoassay using trans-I-beta-galactosidase conjugate. Cross-reactivity studies indicated that the antiserum was highly specific for the tetralin structure and for substitution at the C2 position. The antiserum also selectively discriminated the stereoisomers about the C1-C2 bond. The anti-trans-I serum was used to develop EIA for trans-5-hydroxymethyl-6-hydroxy-2-isopropylamino-1,2,3,4-tetrahydronapht halene- 1-ol (IIb), which exhibited strong beta-stimulating activity fairly selective to tracheal muscle, since it recognized trans-IIb to the same degree as trans-I. The assay could detect as little as 100 pg of this compound. The mean recovery of trans-IIb added to plasma was 105%, and values for plasma trans-IIb determined by this immunoassay correlated well with those determined by gas chromatography-mass spectrometry.

Adrenergic beta-Agonists↗
PubMed1978

Attempts at analysis of toxicity of pertussis vaccine. III. Effects of endotoxin on leukocytosis in mice due to lymphocytosis-promoting factor and reference preparations for determination of lymphocytosis-promoting factor.

The effect of bacterial endotoxin on the change in peripheral leukocyte population in mice due to the lymphocytosis-promoting factor (LPF) was investigated. Endotoxin affected not only the total leukocyte count but also the leukocyte proportions at any observation time. Both the coefficient and the intercept of regression of the leukocytic response on dose of LPF were modified by endotoxin. Therefore, in a valid biological assay for LPF using the peripheral leukocyte count as a response, a common reference preparation available for any test materials, irrespective of presence or absence of endotoxin, will be impracticable. Two reference preparations were tentatively established, one being a vaccine and the other an LPF preparation containing little endotoxin. A unitage of LP activity was assigned to each reference preparation. The results also showed that an LPF material to be tested for its possible effects on the lymphatic tissues or the reticuloendothelial system should be free from endotoxin.

Animals↗
PubMed1977

Variables of the rubella hemagglutination tests employing freeze-dried erythrocytes.

The variables which affect the interaction between freeze-dried one-day-old chick erythrocytes and rubella hemagglutinin prepared from rubella-infected porcine kidney cells were defined and evaluated. The sensitivity of the hemagglutination (HA) reaction is much greater at pH 6.0 to 6.2 than at pH 7.0 to 7.5 HEPES (N-2-hydroxyethylpiperazine-N'-2'-ethanesulfonic acid) diluent with added Ca+ or Mg2+ ion gave four- to eightfold higher HA titers than one without divalent cations. The development of agglutinated and non-agglutinated erythrocyte patterns depended much upon the concentrations of gelatin and albumin in the HEPES diluent. Gelatin especially was essential to obtain stable and clearly distinguishable patterns. Optimal conditions for the agglutination of freeze-dried erythrocytes by rubella hemagglutinin were provided when a HEPES-buffered saline at pH 6.2, containing 10(-3) M CaCl2, 0.2 per cent bovine serum albumin, and 0.0025 per cent gelatin was employed throughout as a diluent for serum, hemagglutinin, and freeze-dried erythrocyte suspension. This diluent gave maximally sensitive and reproducible results in rubella HA and hemagglutination-inhibition (HI) tests employing freeze-dried erythrocytes.

Animals↗
PubMed1977

Application of freeze-dried monkey erythrocytes to measles viral hemagglutination and hemagglutination-inhibition tests.

Erthrocytes collected from monkey species including grivet, rhesus, and cynomolgus monkeys were stabilized by fixation with glutaraldehyde of a low concentration and were freeze-dried in vacuo. These freeze-dried erythrocytes were compared with fresh erythrocytes for measles viral hemagglutination and hemagglutination inhibition and could be used in both tests instead of fresh erythrocytes. They maintained their initial appearance and sensitivity to measles viral hemagglutinins after storage at 4 degrees C for 4 months more.

Animals↗
PubMed1976

Application of freeze-dried, one-day-old chick erythrocytes to viral hemagglutination and hemagglutination-inhibition tests.

Erythrocytes collected from 1-day-old chicks were stabilized by fixation with formaldehyde and by freeze-drying after treatment with carbon monoxide. Suspensions of freeze-dried erythrocytes in distilled water or physiological saline had a homogeneous bright reddish-purple color. Freeze-dried erythrocytes were compared with fresh erythrocytes for hemagglutination and hemagglutination-inhibition tests for various viruses including rubella, Japanese encephalitis, influenza, mumps, Newcastle disease, and Sendai viruses. After storage at 4 degrees C for 1 year or more, freeze-dried erythrocytes maintained their original appearance and sensitivity to hemagglutination antigens.

Animals↗
PubMed1976

Improved rubella hemagglutination inhibtion test: inactivation of non-immunoglobulin hemagglutination inhibitors by phospholipase C.

A method using phospholipase C (PL-C) for removing nonspecific inhibitors (NSI) of rubella virus hemagglutinin is described. PL-C was found to hydrolyze NSI without altering the hemagglutination inhibition (HI) activity of the specific antibody and could be used to remove NSI in the rubella HI test by using formalinized erythrocytes, which resisted the enzymatic action; fresh erythrocytes were lysed by PL-C. The HI test using PL-C treated sera gave true measurements of actual rubella antibody content, and HI titers of PL-C treated sera were identical or equivalent (+/-1 dilution) to those of sera treated with dextran sulfate and CaCl2 (DS-C). Thus, the PL-C method gave results as reproducible and reliable as the DS-C method and was more convenient.

Antibodies, Viral↗
PubMed1975

Toxicities of influenza vaccine: peripheral leukocytic response to live and inactivated influenza viruses in mice.

Intraperitoneal or intravenous inoculation of live or inactivated influenza virus induced two characteristic responses of the peripheral leukocytes in mice, an early appearing leukopenic response and late appearing lymphopenia. The former response usually developed and subsided within several hours, though the change in leukocyte population was fairly complicated depending upon the activity of the inoculated material, while the latter began several hours after inoculation and reached its minimum level in 10 to 20 hr. The agent responsible for the former may be virus pyrogen, while the latter seems to be caused by some substance(s) other than that. The early appearing leukopenic response was similar to that due to bacterial endotoxin in respect to the characteristic pattern of the change in peripheral leukocyte population, though it was relatively easy to distinguish one from the other by the length of the latent period and by the heat stability of the causative agent. Live or inactivated influenza virus causing the early appearing leukopenic response was found also to have the mouse body weight-decreasing toxicity. The significance of these findings in the laboratory control test of influenza vaccine for untoward reactions often observed in human inoculated with some inactivated influenza vaccines was discussed. The possible roles of the two agents, virus pyrogen and endotoxin, in the febrile response were mentioned.

Animals↗
PubMedDate not supplied

Endotoxin, histamine-sensitizing factor and lymphocytosis-promoting factor contents of pertussis vaccines produced in Japan.

The amounts of endotoxin, histamine-sensitizing factor and lymphocytosis-promoting factor contained in combined diphtheria-pertussis-tetanus and combined diphteria-pertussis vaccines recently produced in Japan were determined and the relationships among them were statistically analyzed. The estimated values in histamine-sensitizing units (HSU) and lymphocytosispromoting units (LPU) per human dose ranged from 0.3 to 6 and from 0.4 to 5, respectively. A fairly wide range of endotoxin contents, which were expressed in body weight-decreasing units (BWDU), was also demonstrated. All the ranges were larger than those expected from experimental error. There was a positive correlation between the HSU and LPU values although the individual HSU-LPU ratios ranged from 0.3 to 3, but the range was markedly larger than the width of the 95% confidence interval of the mean ratio. Negative correlation between BWDU and LPU was also significant, probably because of the relatively large number degrees of freedom, though the coefficient was fairly small; while that between BWDU and HSU was not significant. The frequency distribution of individual values of HSU was divided into two lognormal distributions. With one of the two groups obtained by this subdivision, a distinct positive correlation bewteen HSU and LPU was demonstrated, but with the other group there was little correlation. Some differences between the two groups were also found in the correlations between BWDU and the other two variates. No factors responsible for the separation of the groups have yet been found.

Animals↗