Biomedical subjects

T Minkus

Publications and source records attributed to T Minkus.

4 recordsLinked to original sources

PubMed1998

Impact of unified procedures as implemented in the Canadian Quality Assurance Program for T lymphocyte subset enumeration. Participating Flow Cytometry Laboratories of the Canadian Clinical Trials Network for HIV/AIDS Therapies.

The objective of the Canadian Quality Assurance Program (CQAP) is to provide the most reproducible and accurate T-cell subset enumeration for individuals living with HIV who are enrolled in the Canadian Clinical Trial Network for Human Immunodeficiency Virus (HIV) and Acquired Immune Deficiency Syndrome (AIDS) Therapies (abbreviated as CTN). The Canadian National Laboratory for Analytical Cytology, within the Laboratory Centre for Disease Control, is part of the Health Protection Branch of Health Canada. For the past eight years, the Laboratory for Analytical Cytology has been responsible for delivering a bilingual quality assurance program for CD4 T-cell enumeration. This federal program, which integrates biotechnology transfer with quality assessment, was achieved through the organization of workshops focused on technology transfer and essential skill-building techniques. Two training sessions were conducted for the CTN flow cytometer operators. The first introduced the concept of window of analysis, to demonstrate the practical benefits of unified quantitative fluorescent measurement. As a follow-up to the first workshop, participants performed a series of quantitative assays that monitored the expression of CD69, an early activation marker. This quantitative fluorescence protocol was performed with acceptable inter-laboratory variation using modified commercial kits. The second workshop focused on a absolute count method based on a single platform. Four preserved whole-blood preparations were tested with this approach. The combined effort reduced inter-laboratory variation. The direct impact was monitored as related to the frequency of participation. Over the years, the standard deviation of average accumulated variation decreased dramatically with increased frequency of participation, from 10% to <4%.

Canada↗

PubMed1998

Amplicor HIV monitor, NASBA HIV-1 RNA QT and quantiplex HIV RNA version 2.0 viral load assays: a Canadian evaluation.

BACKGROUND: HIV-1 viral load quantitation is now recognized as a useful tool to monitor the efficiency of antiviral treatment and a powerful predictor of disease outcome. Three HIV-1 viral load quantitation methods have been currently available as commercial kits in Canada since 1996. OBJECTIVE: To evaluate the ability to quantify HIV-1 RNA in plasma of the Amplicor HIV Monitor Test, the NASBA HIV-1 RNA QT Assay and the Quantiplex HIV RNA Assay, version 2.0, at comparable lower detection limits. STUDY DESIGN: Blood was collected from 50 HIV-1-infected patients at various stages of infection and therapy. CD4+ cell count were estimated by flow cytometry. Plasma was isolated and tested in duplicate on four occasions using viral load kits from a single lot. HIV RNA data, performance, sensitivity and intra- and inter-assay variability were compared. RESULTS: RNA could be quantified in 33 patients by each technique. An inverse correlation was observed between viral load level and CD4+ cell counts in patients with counts below 200. Monitor could detect RNA in 94% of patients, but it showed the greatest variability and failure rate. Quantiplex 2.0 could detect HIV-1 RNA in 78%, and NASBA in 88% of the patients at theoretically equivalent lower detection limits, suggesting that the detection limit of Quantiplex 2.0 may be higher than 500 HIV-1 RNA copies per ml. NASBA had the fewest invalid tests and good reproducibility, comparable to that of Quantiplex 2.0. The mean values from NASBA and Monitor were the most similar but the best correlation was observed between Monitor and Quantiplex 2.0 results. CONCLUSIONS: Monitor, NASBA and Quantiplex results were comparable, although those obtained by Quantiplex were significantly lower. Performing this study at comparable detection limits showed that the detection limit of Quantiplex 2.0 may be higher than stated by the manufacturer.

Adolescent↗

PubMed1997

Evolution of leukocyte immunophenotyping as influenced by the HIV/AIDS pandemic: a short history of the development of gating strategies for CD4+ T-cell enumeration.

This brief review of the development of gating strategies for CD4+ T-cell enumeration is really the story of contemporary clinical flow cytometry. It is the chronicle of its birth, and its slow invasion into the clinical immunology laboratory over the past 15 years. The driving force behind the technological evolution of leukocyte immunophenotyping was, and still is, the impact of the HIV/AIDS pandemic on the discipline of immunology. While, at times, this review of analytical flow cytometry makes metaphorical excursions into the literary world, the objective is not to trivialize technology. Rather, it attempts to illustrate how, in his drive to solve the practical problems of modern medicine, man's essentially eclectic nature excels in an environment of diverse knowledge. This review will examine how technological advancements, such as the introduction of clinical instruments with multi-color capabilities, and the evolution of leukocyte gating strategies, has influenced the evolution of leukocyte immunophenotyping.

Acquired Immunodeficiency Syndrome↗

PubMed1995

Principles of flow cytometry.

Clinical flow cytometry is a relatively new and rapidly growing medical technology. According to estimates, there were less than 1000 instruments in operation globally prior to 1985. Most of these instruments were used exclusively for research, and required dedicated facilities and operators with extensive backgrounds in electronics. In the mid-1980s, with the availability of benchtop clinical models, the number of flow cytometers jumped dramatically, surpassing 4000 by 1990. Most of the instruments that have been sold in the past decade are equipped with low power, air-cooled argon ion lasers with a fixed emission light wavelength at 488 nm. They are capable of multi-color immunophenotyping, and are usually connected to powerful personal computers for data analysis. By 1992, there were an estimated 7000 flow cytometers in operation worldwide. Today, the three general fields where this technology is well established are clinical immunology, laboratory hematology, and medical oncology. The most prominent uses of flow cytometers are for immunological characterization of lymphomas and leukemias, crossmatching tissues for organ transplants, and counting lymphocyte subpopulations in the peripheral blood of HIV-infected individuals. In this review, a brief historical introduction will be followed by a general description of some of the salient features of clinical flow cytometers.

Flow Cytometry↗