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Maurice R G O'Gorman

Publications and source records attributed to Maurice R G O'Gorman.

4 recordsLinked to original sources
PubMed2007

Assessing immunophenotyping performance: proficiency-validation for adopting improved flow cytometry methods.

BACKGROUND: The continuous improvement and evolution of immune cell phenotyping requires periodic upgrading of laboratory methods and technology. Flow cytometry laboratories that are participating in research protocols sponsored by the NIAID are required to perform "switch" studies to validate performance before methods for T-cell subset analysis can be changed. METHODS: Switch studies were conducted among the four flow cytometry laboratories of the Multicenter AIDS Cohort Study (MACS), comparing a 2-color, lyse-wash method and a newer, 3-color, lyse no-wash method. Two of the laboratories twice failed to satisfy the criteria for acceptable differences from the previous method. Rather than repeating more switch studies, these laboratories were allowed to adopt the 3-color, lyse no-wash method. To evaluate the impact of the switch to the new method at these two sites, their results with the new method were evaluated within the context of all laboratories participating in the NIH-NIAID-Division of AIDS Immunology Quality Assurance (IQA) proficiency-testing program. RESULTS: Laboratory performance at these two sites substantially improved relative to the IQA standard test results. Variation across the four MACS sites and across replicate samples was also reduced. CONCLUSIONS: Although switch studies are the conventional method for assessing comparability of laboratory methods, two alternatives to the requirement of repeating failed switch studies should be considered: (1) test the new method and assess performance on the proficiency testing reference panel, and (2) prior to adoption of the new methods, use both the old and the new method on the reference panel samples and demonstrate that performance with the new method is better according to standard statistical procedures. These alternatives may help some laboratories' transition to a new and superior methodology more quickly than if they are required to attempt multiple, serial switch studies.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Impact of inversion of the CD4/CD8 ratio on the natural history of HIV-1 infection.

BACKGROUND: HIV-1 infection is characterized by an inverted CD4/CD8 T-cell ratio, but the distribution of inversions over time after seroconversion and whether delay of inversion is associated with a favorable prognosis are not known. METHODS: T-cell counts and clinical outcomes among men in the Multicenter AIDS Cohort Study who had incident HIV-1 infection before December 31, 1995 were analyzed by Kaplan-Meier and Cox proportional hazards methods. Results were also analyzed by time-dependent multivariate methods to adjust for CD4 lymphocyte counts, viral loads, age, race, and polymorphisms in host chemokine receptor genes (CCR5-Delta32 and CCR2-64I). RESULTS: Among 424 cases whose date of seroconversion was known to within +/-4.5 months, 317, 52, and 55 inverted their CD4/CD8 ratio within less than 1, 1 to 2, and more than 2 years of seroconversion, respectively. Longer time to inversion was significantly associated with longer time to AIDS, even after adjusting for CD4 lymphocyte count and viral load at the first seropositive visit and over the first 3 seropositive visits. Of the 6 seroconverters who had more than 500 CD4 lymphocytes 10 years after seroconversion without receiving highly active antiretroviral therapy, 5 took more than 2 years to invert their CD4/CD8 ratio. CONCLUSIONS: Time from HIV-1 seroconversion to inversion of the CD4/CD8 ratio independently predicted time to AIDS. Early measurements of the CD4/CD8 ratio until inversion occurs may identify people likely to become long-term nonprogressors or slow progressors, thus facilitating detailed studies of the mechanism of HIV-1 disease progression.

Adult↗