University of North Florida
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Contact Info

Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Masako Maeda

Abbrev:
Maeda, M.
Other Names:
Address:
School of Pharmaceutical Sciences, Showa University, 1-5-8, Hatanodai, Shinagawa, Tokyo 142-8555
Phone:
+81-3-3784-8193
Fax:
+81-3-3784-8247

Citations 7

"Simultaneous Determination Of α-fetoprotein, Human Chorionic Gonadotropin And Estriol In Serum Of Pregnant Women By Time-resolved Fluoroimmunoassay"
J. Pharm. Biomed. Anal. 1999 Volume 20, Issue 1-2 Pages 169-178
Katsutoshi Ito, Miwa Oda, Akio Tsuji and Masako Maeda

Abstract: We have developed a simple and rapid time-resolved fluoroimmunoassay (TR-FIA) for simultaneous determination of α-fetoprotein (AFP), human chorionic gonadotropin (hCG) and estriol (E3) using europium and samarium ion chelate. In the proposed method, we used a combination of a 96-well microtiter plate for the AFP and hCG assay and transferable solid phase plate for the E3 assay. Therefore, these analytes could be measured simultaneously. The measurable ranges for AFP, hCG and E3 by the proposed method were 3.91-1000 ng mL-1, 877-250 000 IU L-1 and 0.39-100 ng mL-1, respectively. The proposed method which utilized characteristics of a rare earth ion chelate, was convenient (unnecessary diluting samples), quick (96 assays for 2 h), and required only a small quantity sample (50 µl). The principle of this proposed method is applicable to other antigens.

"Chemiluminescent Assay Of Enzyme Activity And Its Application To FIA"
J. Flow Injection Anal. 1990 Volume 7, Issue 2 Pages 87-100
A. Tsuji and M. Maeda

Abstract: A review of the use of chemiluminescence in FIA for enymatic reactions is presented (27 references)
Chemiluminescence Activity Enzyme Review

"Simultaneous Determination Of Galactose And Galactose-1-phosphate In A Dried-blood Disc By Semi-micro Flow Injection Analysis Using An Enzyme-immobilized Column And Its Application To Neonatal Screening For Galactosemia"
Bunseki Kagaku 2000 Volume 49, Issue 12 Pages 953-959
Katsutoshi Ito, Masumi Mitome, Hidetoshi Arakawa and Masako Maeda

Abstract: We have developed a simultaneous determination of galactose (Gal) and galactose-1-phosphate (G1P) by a semi-micro flow injection analysis (FIA) system using an enzyme-immobilized column. This method was applied to preliminary neonatal mass-screening for galactosemia. A galactose dehydrogenase (Gal-DH) and alkaline phosphatase (ALP) were immobilized to TSK-gel Tresyl 5PW (Tosoh Co., Tokyo) and packed into a column (1.5 i.d. x 50 mm for Gal-DH and 1.5 i.d. x 100 mm for ALP). The enzyme-immobilized columns were connected to high-pressure 6-way valves. In the proposed method, the detection limits (S/N = 3) of Gal and GIP were 3.5 x 10^-13 and 5.4 x 10^-13 mol/assay, respectively. The measurable ranges for Gal and GIP were 2 similar to 20 and 5.5 similar to 23.8 mg/dl in the standard dried-blood disc (3 mm i.d.) on filter paper, respectively. The accuracy of an intra-assay at each point of the standard disc (n = 5) was less than 1.0%. The mean recoveries (n = 10) of Gal and G1P from a dried-blood disc were 99.3 and 84.8%, respectively. Further, we measured the Gal and G1P concentrations of neonatal blood-disc samples by the proposed method and compared the results with a conventional fluorescent enzymatic method. The regression equations determined for the results were y (FIA) 0.976x (enzymatic method) - 0.929 (r = 0.954, n = 11) for Gal and y (FIA) = 1.197x (enzymatic method)- 0.539 (r = 0.824, n = 11) for GIP, respectively. A high degree of correlation was observed between the values obtained by the proposed FIA and those by the conventional enzymatic method. The proposed method could quantitatively measure Gal and GIP in one dried-blood disc on filter paper for 13 min.

"Simultaneous Determination Of Phenylalanine, Leucine And Galactose In A Dried-blood Disc By Semi-micro FIA Using An Enzyme-immobilized Column And Its Application To Neonatal Mass-screening For Inborn Errors Of Metabolism"
Bunseki Kagaku 2000 Volume 49, Issue 6 Pages 355-361
Masumi Mitome, Katsutoshi Ito, Hidetoshi Arakawa and Masako Maeda

Abstract: We have developed a simultaneous determination of phenylalanine (Phe), leucine (Leu) and galactose (Gal) by a semi-micro flow injection analysis system using an enzyme-immobilized column. This method was applied to preliminary neonatal mass-screening for inborn errors of metabolism. Enzyme-immobilized gel was prepared with Phe, Leu or Gal dehydrogenase using a TSK-gel Tresyl 5PW (Tosoh Co., Tokyo), which was easily linked to the amino group of protein and packed into a column(1.5 i.d. x 100 mm). The enzyme-immobilized columns were connected to high-pressure six-way valves. In the proposed method, the detection limits (S/N = 3) of Phe, Leu and Gal were 1.6 x 10^-13, 3.4 x 10^-13 and 1.6 x 10^-13 mol/assay, respectively. The measurable ranges for Phe, Leu and Gal were 0.3-19.6, 0.8-18.4 and 0.4-18.2 mg/dl on the standard dried-blood disc (3 mm i.d.) on filter paper, respectively. The accuracy of an intra-assay with each point of the standard disc (n = 5) was less than 2.4%. The mean recoveries (n = II) of Phe, Leu and Gal from a dried-blood disc were 77.4, 78.5 and 97.4% respectively. Further, we measured the Phe, Leu and Gal concentrations of neonatal blood-disc samples by the proposed method. The levels (mean±SD, n = 30) were 1.5±2.1 (Phe), 2.4±1.4 (Leu) and 2.6±2.1 (Gal) mg/dl, respectively. The proposed method could quantitatively measure amino acids and galactose in one dried-blood disc on filter paper for 17 min.

"Chemiluminescence Flow Injection Analysis Of Biological Compounds Based On The Reaction With Lucigenin"
Anal. Sci. 1986 Volume 2, Issue 2 Pages 183-186
M. MAEDA and A. TSUJI

Abstract: Chemiluminescence reactions of lucigenin with reducing sugars and related compounds and with steroids were investigated by using a flow injection system. For the reducing sugars and related compounds, preliminary incubation at room temperature with 5 mM NaIO4 enhanced the chemiluminescence ~100-fold; corticosteroids and other compounds possessing an α-hydroxycarbonyl group exhibited intense chemiluminescence without NaIO4 treatment. Compounds without an α-hydroxycarbonyl group did not undergo the chemiluminescence reaction. For glucose, with NaIO4 pre-treatment, response was rectilinear from 50 to 700 pmol; without NaIO4 treatment, the detection limit was 50 nmol.
Glucose Carbohydrates Corticosteroids Chemiluminescence Optimization

"New Electrochemical Assay Of Alkaline Phosphatase Using Ascorbic Acid 2-phosphate And Its Application To Enzyme Immunoassay"
Anal. Chim. Acta 2000 Volume 407, Issue 1-2 Pages 119-125
Amane Kokado, Hidetoshi Arakawa and Masako Maeda

Abstract: An alternative substrate is described for an enzyme immunoassay with electrochemical detection, Alkaline phosphatase (ALP) activity is determined by using ascorbic acid 2-phosphate (AsA-P) as substrate. ALP-generated-AsA is detected amperometrically at a glassy carbon electrode in a flow injection system at +400 mV. The optimum assay conditions (pH, incubation time and concentration of reagent) are examined for the ALP assay. The detection limit of ALP was 160 amol per assay (7 amol per injection). On electrochemical detection, many ALP assays using p-aminophenyl phosphate or phenyl phosphate as substrate have been reported. The sensitivity for ALP by the proposed method is almost the same as those of the methods for ALP using p-aminophenyl phosphate or phenyl phosphate. The proposed method was applied to the enzyme immunoassay of human chorionic gonadotropin (hCG) using ALP as a label enzyme. The detection limit of hCG was 2 mIU mL-1. Comparison of the results obtained by the proposed electrochemical EIA and time-resolved fluoroimmunoassay showed excellent agreement (r = 0.997, n = 50). The proposed electrochemical EIA could be performed within 4 h. and could be useful for routine assay in clinical diagnosis.
Enzyme, alkaline phosphatase Immunoassay Amperometry Electrode Clinical analysis Method comparison Optimization

"Chemiluminescent Flow Injection Determination Of Alkaline Phosphatase And Its Applications To Enzyme Immunoassays"
Anal. Chim. Acta 1997 Volume 339, Issue 1-2 Pages 139-146
Jin-Ming Lin, Akio Tsuji and Masako Maeda*

Abstract: The flow injection chemiluminescence method for determining alkaline phosphatase (ALP) was based on the catalyzed reaction of cortisol-21-phosphate to produce cortisol which was detected by its chemiluminescence reaction with lucigenin (NN'-dimethyl-9,9'-biacridinium dinitrate). Sample (100 µL) was injected into a Tris hydrochloride buffer carrier stream (0.5 ml/min) at pH 10 which was merged with the reagent stream (1.5 ml/min) containing 0.1 mg/mL lucigenin and 0.06% cetyltrimethylammonium bromide in 0.1 M NaOH. The chemiluminescence was detected using a photomultiplier tube. The calibration graph for 4-50 pM-ALP was presented. The detection limit was 1 pM-ALP and the RSD (n = 5) was <6.1%. The method was applied to FIA for 17-α-hydroxyprogesterone and human chorionic gonadotropin in urine or serum using ALP as the enzyme label. The results correlated with those obtained by other methods.
Enzyme, alkaline phosphatase 17-Hydroxyprogesterone Gonadotropin chorionic Serum Human Urine Chemiluminescence Immunoassay Catalysis Method comparison