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The A/C Enzymatic Vitamin B6 Assay is intended for the quantitative in vitro diagnostic determination of pyridoxal 5'-phosphate (PLP, vitamin Bo) in EDTAhuman plasma. The device will be used to monitor PLP concentrations in plasma for aid in diagnosis of vitamin B6 deficiency. The A/C Enzymatic Vitamin B6 Assay is for IN VITRO DIAGNOSTIC USE ONLY.

The A/C Enzymatic Vitamin B6 Assay is calibrated with external standardization and matrix-matched calibration solutions. Two sources of quality control material (A low and high level of PLP) are assaved in each run together with A/C Calibrators and samples for the verification of the accuracy and precision of the A/C Enzymatic Vitamin B6 Assay. The A/C Enzymatic Vitamin B6 Assay uses the apo form of recombinant PLPdependent enzyme, homocysteine-a.y-lyase (rHCYase). The restoration of enzymatic activity by reconstitution of the holo-enzyme is linearly dependent on the amount of PLP bound to apo-enzyme. Nanomolar concentrations of PLP can then be measured by the conversion of millimolar concentrations of homocysteine to hydrogen sulfide, which is determined using DBPDA, the combination of which forms a chromophore, the absorbance is read with 96-well plate absorbance reader. The A/C Enzymatic Vitamin B6 Assay is a three-step reaction with four reagents. which runs at 37°C or room temperature. The total assay takes 90 minutes. The assay can be performance on 96-well absorbance reader with 660-690m filter.

The A/C Portable Enzymatic Homocysteine Assay on the A/C Diagnostics Reader (HyTek-205) is intended for the quantitative determination of total homocysteine (tHCY) in human plasma or serum. The device can assist in the diagnosis and treatment of patients suspected of having hyperhomocysteinemia. The A/C Enzymatic Homocysteine Assay is for in vitro diagnostic use.

The A/C Portable Enzymatic Homocysteine Assay is calibrated with A/C Enzymatic Homocysteine Assay Calibrators. A/C Enzymatic Homocysteine Assay Controls are assayed for the verification of the accuracy and precision of the A/C Portable Enzymatic Homocysteine Assay. The A/C Enzymatic Homocysteine Assay measures tHCY. The principle of the assay is that after reduction, tHCY is depleted by Homocysteinase (rHCYase) and produces hydrogen sulfide (H2S), which is determined using N.N-dibutyl phenylene diamine (DBPDA), the combination of which forms a chromophore, the fluorescence is measured by the A/C Diagnostics Reader (HyTek-205). The A/C Portable Enzymatic Homocysteine Assay is a three-steps reaction, which runs at room temperature. The total assay takes 80 minutes, and the A/C Diagnostics Reader is the only equipment needed.

- The A/C Enzymatic Homocysteine Assay is intended for the quantitative determination of total homocysteine (tHCY) in human plasma or serum. - The device can assist in the diagnosis and treatment of patients suspected of having hyperhomocysteinemia. - The A/C Enzymatic Homocysteine Assay Kit is only for in vitro diagnostic use.

The A/C Enzymatic Homocysteine Assay is calibrated with A/C Enzymatic Homocysteine Assay Calibrators. The A/C Enzymatic Homocysteine Assay is assayed for the verification of the accuracy and precision on the Hitachi 912 Automatic Analyzer. The A/C Enzymatic Homocysteine Assay measures tHCY. The principle of the assay is that recombinant homocysteinase (rHCYase) produces hydrogen sulfide (H2S) from tHCY, which is quantified by use of N,N-dibutyl phenylene diamine (DBPDA), the combination of which forms a chromophore. The A/C Enzymatic Homocysteine Assay on the Hitachi 912 Automatic Analyzer used four reagents, a number compatible with implementation on the Hitachi 912 Automatic Analyzer. We used 30 uL of EDTA plasma in a dithiothreitol (DTT) reduction reaction (1 mmol/L DTT, 0.2% Triton X-100 in 40 mmol/L sodium phosphate buffer [pH 8.3]) for 1.5 minutes to release bound homocysteine. The rHCYase reaction (0.05 mg/ml in 40 mmol/L sodium phosphate buffer [pH 8.3] with 20 umol/L pyridoxal 5-phosphate [PLP]) is then run for 3.5 minutes. The DBPDA chromophore (12.5 mmol/L DBPDA in 1.5 N H2SO4) is then added and 5 minutes later, an oxidant, potassium ferricyanide (5 mmol/L K3Fe(CN), in 10 mmol/L sodium phosphate buffer [pH 7.6]), is added. Five minutes after addition of oxidant, the end-points are read at absorbances of 700 and 660 nm. As the assay is based on an increase in absorbance over baseline, no blank without enzyme was used. The detection limit of the assay is 1.5 umol/L defined by quantification of a serial dilution of a plasma sample of tHCY diluted to 0.77 umol/L. The limit of quantification is defined as the lowest concentration measured having a CV <20%. The linear range extends to at least 80 umol tHCY/L as determined by measuring varying amounts of homocysteine in phosphate buffered saline. The within-run imprecisions (CV) run over 8 repeats were 4.8% at 8.9 umol/L tHCY; 3.0% for 14.9 umol/L tHCY; and 4.5% for 25 umol/L tHCY. Between-assay imprecisions (CV) over 10 days were 7.8% for 8.8 umol/L tHCY: 5.9% for 15 umol/L tHCY; and 4.9% for 25 umol/L tHCY. These imprecisions are with in ranges reported for currently-used assays including the Bio-Rad HCY assay on HPLC, which is used as a comparison method in the present study. The results showed that L-cysteine (L-CYS) in the physiological concentrations (0-200 µmol/L) had less than 10% interference and L-methionine (L-MET) in the physiological concentrations (0-200 umol/L) had no interference in the A/C Enzymatic Homocysteine Assay on the Hitachi 912 Automatic Analyzer. The A/C Enzymatic Homocysteine Assay on the Hitachi 912 Automatic Analyzer is a four-step reaction. The total assay takes 15 minutes, and the through-put is 360 tests per hour.