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T Saita

Publications and source records attributed to T Saita.

34 records · Page 2Linked to original sources
PubMed1993

[An evaluation of tumor markers and risk factors in mass screening for various cancers].

The borderline values of tumor markers and the clarification of risk factors for cancer are problems to be solved in the development of mass screening tests for various cancers. A tiny abnormality may be overlooked in an evaluation based upon traditional reference standards obtained by surveying healthy subjects. Both negative and positive values are required in mass screening for various cancers. That is, cut-off values should minimize the incidence of false negatives and false positives in the screening test. A modified combination assay using tumor markers and risk factors was used to screen 967 healthy subjects over age 50 for nonspecific cancers and the results were analyzed. Positive rates based on ordinary cut-off values for each tumor marker were about 6 to 7% in CEA, CA19-9 and BFP, 2.7% in SPAN-1, 1.3% in PAP, and less than 1% in AFP, SCC, CA125 and NCC -ST-439. For pepsinogen, a risk factor of various cancers especially in the digestive tract, the cut-off value was determined as the mean-SD in 967 healthy subjects over 50 years old. That is, the cut-of value for pepsinogen I was 18.7 ng/ml. A lower value was found in 149 subjects (15.4%). The cut-off value for pepsinogen II was 7.4 ng/ml and a lower value was found in 227 subjects (23.5%). The cut-off value for the pepsinogen I/II ratio was 1.2 and 108 subjects showed lower values (11.2%). Positive cases were referred to specialists in various fields to detect the specific suspected cancer.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

A highly sensitive enzyme-linked immunosorbent assay for etoposide using beta-D-galactosidase as a label.

A highly sensitive enzyme-linked immunosorbent assay (ELISA) for etoposide (EP) was developed, which is capable of accurately measuring as little as 40 pg EP/ml. Anti-EP sera were obtained by immunizing rabbits with EP conjugated with mercaptosuccinyl bovine serum albumin (MS.BSA) using N-[beta-(4-diazophenyl)ethyl]maleimide (DPEM) as a heterobifunctional coupling agent. An enzyme marker was similarly prepared by coupling EP with beta-D-galactosidase (beta-Gal; EC 3.2.23) via DPEM. This ELISA was specific for EP and showed a very slight cross-reactivity with its major metabolite, cis-hydroxy acid of EP (0.91%), but none with 4'-demethylepipodophyllotoxin and drugs commonly used with EP in combination chemotherapy for cancer treatment. The values for EP concentration detected by this assay were comparable with those detected by the high-performance liquid chromatography (HPLC) method. However, the ELISA was about 1,250 times more sensitive in detecting EP at lower concentrations. Using this assay, drug levels were easily determined in the blood and urine of rats for 7 h after i.v. administration of EP at a single dose of 3 mg/kg. Due to its sensitivity and specificity for EP, the ELISA should prove to be a valuable new tool for use in clinical pharmacological studies.

Animals↗
PubMed1988

Enzyme-linked immunosorbent assay for the quantification of actinomycin D using beta-D-galactosidase as a label.

An enzyme-linked immunosorbent assay (ELISA) for actinomycin D (AMD) has been developed, which allowed us to measure accurately as little as 50 pg of AMD per assay well. Anti-AMD sera was obtained by immunizing rabbits with an AMD derivative, 7-aminoactinomycin D (7AMD), conjugated with mercaptosuccinyl bovine serum albumin via N-maleoylaminobutyric acid chloride as a coupling agent. An enzyme marker was similarly prepared by coupling 7AMD with beta-D-galactosidase (EC 3.2.1.23) via N-maleoylaminobutyric acid. The ELISA with anti-AMD immunoglobulin G fraction as a solid phase and 7-aminoactino-mycin beta-D-galactosidase conjugate was specific to AMD as well as 7 AMD and showed 30% cross-reaction with actinomycin V, while no cross-reactivity was seen with drugs commonly used with AMD in combination chemotherapy for cancer treatment. The sensitivity of the ELISA was about 1000 times higher than high performance liquid chromatography in detecting AMD in lower concentrations. Using this assay, drug levels were easily measured in the blood and urine of rats following administration of AMD in a single dose of 0.25 mg/kg i.v. These results indicate that the ELISA provides a nonradioactive, inexpensive, sensitive, and rapid method applicable for pharmacological analyses of the drug.

Animals↗
PubMed1988

The use of N-[beta-(4-diazophenyl)ethyl]maleimide as a coupling agent in the preparation of enzyme-antibody conjugates.

The present study was undertaken to develop a novel method for the enzyme labeling of antibodies. Goat anti-rabbit IgG was used as a prototype and coupled to beta-D-galactosidase (Gal) with a new heterobifunctional cross-linking agent N-[beta-(4-diazophenyl)ethyl]maleimide (DPEM). The antibody was first azo-coupled with DPEM to introduce the maleimide groups into the molecule; excess reagent was removed by gel filtration and then the activated antibodies were crosslinked to the thiol groups of Gal. The conjugates were purified by DEAE-cellulose column chromatography, being completely separated from non-reacted antibodies but remaining mixed with free Gal, and showing approximately 30% enzyme activity bound to antibody. This method is simple, reproducible and so mild that almost full enzyme and antibody activity can be retained. The conjugates were used as a label in an immunoassay and were able to detect first antibody at concentrations as low as 2 ng/tube. Furthermore, the present method was compared with the method using N-(gamma-maleimidobutyryloxy)succinimide (GMBS), and it was found that both conjugates produced comparable results.

Animals↗
PubMed1987

The use of N-[beta-(4-diazophenyl)ethyl]maleimide as a heterobifunctional agent in developing enzyme immunoassay for neurotensin.

A heterobifunctional crosslinking agent N-[beta-(4-diazophenyl)ethyl]maleimide (DPEM) was newly synthesized and characterized to possess the maleimide group with a stability greater than that previously reported for N-(4-diazophenyl)maleimide. Using the peptide hormone neurotensin (NT) as a model hapten, DPEM was used in the conjugation reaction with bovine serum albumin (BSA) and with beta-D-galactosidase (beta-Gal) in developing an enzyme immunoassay (EIA) for NT. The NT-DPEM-BSA conjugate elicited anti-NT antibodies in rabbits and the NT-beta-Gal conjugate behaved as an enzyme marker of NT in the EIA. The EIA developed double antibody was reproducible and sensitive in detecting NT at concentrations as low as 30 fmol per tube. The specificity of anti-NT serum seems to be primarily toward the carboxy-terminal region of NT, showing cross-reactions with such NT fragments as NT2-13, NT8-13, and NT1-8 for 120, 22, and less than 0.1%, respectively. The utility of this assay was also demonstrated by measuring the NT immunoreactivity in several rat organs. DPEM could be useful for developing EIAs for other peptide hormones (even those which contain neither a free amino group nor a free carboxyl group), using the imidazole, phenolic, or indole group(s) of amino acids as a binding site for carrier proteins.

Cross-Linking Reagents↗
PubMed1987

Isonicotinic acid hydrazide as an antigen.

Detection by in vitro serologic techniques of circulating antibody directed against isonicotinic acid hydrazide (INH, known as isoniazid) in humans has not been reported. In the past few months, however, sera from a patient with a recent history of isoniazid hypersensitivity of the immediate type have been studied, and reaginic antibodies (IgE) specific to INH were detected by means of an enzyme-linked allergosorbent test. Preliminary enzyme-linked allergosorbent tests also demonstrated that INH-specific IgE occurred in the serum of two of 150 patients with tuberculosis who had been treated with INH.

Adult↗
PubMed1986

Novel enzyme immunoassay for thyrotropin-releasing hormone using N-(4-diazophenyl)maleimide as a coupling agent.

A novel enzyme immunoassay (EIA) for thyrotropin-releasing hormone (TRH) was developed which used N-(4-diazophenyl)maleimide (DPM) as a new heterobifunctional agent capable of cross-linking TRH to mercaptosuccinyl bovine serum albumin and to beta-D-galactosidase. The resulting conjugates act as the immunogen producing anti-TRH serum in rabbits and the enzyme marker of TRH in the EIA, respectively. This EIA with a double-antibody technique was sensitive and reproducible in measuring TRH at concentrations as low as 50 pg per tube, and monospecific to the hormone showing no cross-reactivity with the hormone analogue L-pGlu-L-His-L-Pro and TRH constituents. Using this assay, the distribution of immunoreactive TRH in the brain was determined easily in rats. The use of DPM should provide a valuable new method for developing EIA hitherto possible for other peptide hormones containing neither a free carboxy nor a free amino group, using imidazole, phenolic, and indole group(s) of the amino acid as a reaction site.

Animals↗
PubMed1986

Enzyme immunoassay for the quantification of mithramycin using beta-D-galactosidase as a label.

A sensitive enzyme immunoassay for mithramycin (MTM) has been developed by using antibody induced in rabbits, beta-D-galactosidase-labeled MTM, and a double-antibody separation technique, which allowed us to measure accurately as little as 100 pg of MTM per assay tube. MTM-antibody was produced against MTM-bovine serum albumin conjugate prepared by the use of diazotized p-aminobenzoic acid as a cross-linker. The beta-D-galactosidase-labeled MTM conjugate was similarly prepared by a geometric m-isomer of diazotized aminobenzoic acid. This enzyme immunoassay was specific to MTM and showed a very slight cross-reactivity with MTM analogues, chromomycin A3 (5.6%) and olivomycin (2.4%), but no cross-reactivity with drugs commonly used with MTM in combination chemotherapy for cancer treatment. The values of MTM concentrations detected by this assay were comparable to those detected by the high-pressure liquid chromatography method. However, the enzyme immunoassay method was 100 times more sensitive in detecting MTM in lower concentrations. Using this assay, drug levels were easily determined in the blood and urine of rats during 6 h after i.v. administration of MTM in a single dose of 2.0 mg/kg. Since MTM has long been used against a variety of human cancers, the enzyme immunoassay of the drug will be a valuable new tool in clinical pharmacological studies.

Animals↗