Manual Gating Research Articles

Use of a phycoerythrin-conjugated anti-glycophorin A monoclonal antibody as a double label to improve the accuracy of FMH quantification by flow cytometry.

The use of flow cytometry for quantifying fetomaternal haemorrhage is increasing, and has been shown to be more accurate than the Kleihauer-Betke test for evaluating larger bleeds of over 4 mL in volume. Red cells are stained with fluorescently labelled monoclonal anti-D. Cells for analysis are normally gated manually on the basis of forward and side scatter. We investigated whether the use of an antiglycophorin A monoclonal antibody conjugate (red cell specific) in a dual labelling technique would improve the gating of RBC and FMH quantification. Mixes of adult rr and cord R1r RBC were prepared to simulate 1, 0.5, 0.25, 0.12 and 0.06% fetal bleeds. Phycoerythrin-conjugated BRIC 256 (mouse monoclonal antiglycophorin A) was used to label all RBC, and FITC-BRAD-3 monoclonal anti-D was used to determine the proportion of D-positive cells. Results from the dual labelling experiments were compared to those from single labelling of the same mixtures with FITC-BRAD-3 alone, using gated and ungated data. The results showed that single labelling with manual gating gave falsely low FMH estimates. We conclude that use of a fluorescently labelled antiglycophorin A antibody improves the accuracy of the FMH measurement by flow cytometry, as manual subjective gating of RBC excludes a higher proportion of fetal than of adult RBC.

Description and Evaluation of Program USM

USM is a hydraulic‐simulation computer program developed by the U.S. Bureau of Reclamation to analyze unsteady‐flow conditions in canals. The program USM uses the method of characteristics to solve the complete Saint Venant equations for unsteady flow in open channels. This solution method yields accurate numerical results but sometimes requires more computer execution time than other methods. USM analyzes canal systems with a variety of structural boundary conditions, including check gates, weirs, siphons, and pumps. Check gates can have either manual or automatic gate control. Branching canals, supercritical flow, and channel dewatering cannot be analyzed. This paper describes the model and compares its strengths and weaknesses with those of other models. Several test data sets compiled by the ASCE Task Committee on Irrigation Canal System Hydraulic Modeling were used in the evaluation. USM simulation results are compared to field data collected from the Central Arizona Project canal system.