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Biomedical subjects

M P Busch

Publications and source records attributed to M P Busch.

194 records · Page 11Linked to original sources
PubMedDate not supplied

False-positive HIV-1 test results in a low-risk screening setting of voluntary blood donation. Retrovirus Epidemiology Donor Study.

CONTEXT: Persons at risk of human immunodeficiency virus 1 (HIV-1) infection, have been classified incorrectly as HIV infected because of Western blot results, but the frequency of false-positive Western blot results is unknown. OBJECTIVES: To determine the frequency of false-positive HIV-1 Western blot results in US blood donors and to make projections to other screened populations. Secondarily, to validate an algorithm for evaluating possible false-positive cases. DESIGN: A retrospective cohort study of HIV-1 enzyme immunoassay (EIA) and Western blot results from large blood donor screening programs in which donors with suspected false-positive Western blot results underwent HIV-1 RNA polymerase chain reaction (PCR) testing and follow-up HIV-1 serology. SETTING: Five US blood centers participating in the Retrovirus Epidemiology Donor Study. PARTICIPANTS: More than 5 million allogeneic and autologous blood donors who successfully donated blood at 1 of the 5 participating centers from 1991 through 1995. MAIN OUTCOME MEASURES: Rate of false positivity by Western blot and true HIV-1 infection status as determined by HIV-1 RNA PCR and by serologic follow-up of blood donors more than 5 weeks after donation. RESULTS: Of 421 donors who were positive for HIV-1 by Western blot, 39 (9.3%) met the criteria of possible false positivity because they lacked reactivity to p31. Of these, 20 (51.3%) were proven by PCR not to be infected with HIV-1. The false-positive prevalence was 4.8% of Western blot-positive donors and 0.0004% (1 in 251000) of all donors (95% confidence interval, 1 in 173000 to 1 in 379000 donors). CONCLUSIONS: A false diagnosis of HIV-1 infection can result from the combination of EIA and Western blot testing in blood donor and other HIV-1 screening programs. Individuals with a positive Western blot result lacking the p31 band should be counseled that, although they may be HIV infected, there is uncertainty about this conclusion. These individuals should be further evaluated by RNA PCR testing (if feasible) and HIV serologic analysis on a follow-up sample.

AIDS Serodiagnosis↗
PubMedDate not supplied

Characterization of the expression of cellular retrovirus genes and oncogenes in feline cells.

Expression of endogenous retrovirus genes and two different cellular oncogenes (c-onc genes) was examined at the transcriptional level in a variety of normal and lymphoma/leukemia tissues of the domestic cat. The two oncogenes, c-myb(related to avian myeloblastosis virus) and c-myc(related to avian myelocytomatosis virus) were selected for their association with the induction of hematopoietic malignancies, when present in the transforming retroviruses. Tissue-specific expression of endogenous feline leukemia virus (FeLV)-related genes was detected in cellular subpopulations of the cat placenta by in situ method of hybridization. Gel blotting analysis of placental poly(A)-selected RNA revealed that the FeLV-related RNA species were primarily subgenomic, representing the env gene region of the endogenous provirus elements. Like the endogenous retrovirus genes, c-myb and c-myc loci of the cat genomic DNA were also transcribed at differential levels in normal tissues of the cat. Dot-blot hybridization analysis showed that the expression of these two oncogenes was linked to growth and development as it varied with the gestational age of the fetus and from fetal to adult tissues. Among the major hematopoietic organs, spleen and bone marrow contained both c-myb and c-myc transcripts, while thymus preferentially expressed the c-myb gene. In contrast to the low level of c-myc expression in fetal thymus tissues, enhanced c-myc expression was detected in all five thymomas tested and also in several other neoplasms including two granulocytic leukemias. The feline c-myb gene was not very active in granulocytic leukemias or in three of the five thymomas. RNA gel blotting analysis of poly(A)-selected RNA of a thymoma and its lymph node metastasis showed identical pattern of c-myc transcripts.

Animals↗
PubMedDate not supplied

How well has self-exclusion worked?

Review of the dates of prior blood donation by persons later reported to have AIDS demonstrated that most of them had ceased donating blood in 1983. The results indicate that self-exclusion policies were effective.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Resolution of infection status of human immunodeficiency virus (HIV)-seroindeterminate donors and high-risk seronegative individuals with polymerase chain reaction and virus culture: absence of persistent silent HIV type 1 infection in a high-prevalence area.

To address concerns over the prevalence of silent (antibody-negative) infections among blood donors and high-risk populations, a combination of proviral amplification by polymerase chain reaction (PCR) and viral isolation by co-culture techniques was employed to resolve the human immunodeficiency virus type 1 (HIV-1) infection status of well-characterized groups of suspect blood donors and others identified in the blood bank setting. No silent infections were found in 65 follow-up samples from 26 persistently HIV-1-seroindeterminate blood donors, 16 persistently seronegative heterosexual partners of infected transfusion recipients, and 6 high-risk seronegative homosexual men identified through donor look-back investigations. In contrast, 21 seropositive controls tested positive. These results suggest a low prevalence of persistently silent infections in at-risk populations, even in high HIV prevalence regions. The PCR assay, with a co-detected internal positive control, and appropriate confirmatory algorithms, was found to be a useful direct assay to rule out infection, especially in concert with confirmatory virus isolation.

Blood Donors↗
PubMedDate not supplied

Quantitation of residual white cells in filtered blood components by polymerase chain reaction amplification of HLA DQ-A DNA.

BACKGROUND: Over the past several years, blood filtration technology has improved dramatically, such that currently available experimental filters are capable of reducing white cells (WBCs) in blood components to less than 0.1 WBC per microL. These residual WBC concentrations are below the sensitivity of automated cell counters, as well as of large-volume (Nageotte) hemocytometers. STUDY DESIGN AND METHODS: A quantitative polymerase chain reaction (PCR) amplification assay directed at HLA DQ-A DNA sequences has been developed for the enumeration of WBCs in filtered blood. To ensure quantitative recovery of WBCs at very low residual cell concentrations, a direct red cell lysis and WBC concentration protocol using 0.5 mL of filtered blood was perfected. Amplified product is detected by oligomer hybridization using 32P-labeled probes, with quantitation by image analysis of autoradiographic signals relative to a standardized dilution series processed in parallel. RESULTS: Recovery of residual WBCs in filtrates was shown to be enhanced by the addition of xenogeneic WBCs or polystyrene beads, which served as "carrier" particles during red cell lysis and wash steps. A contribution of nuclear fragments in filtered blood to PCR signal in the range of 0.01 to 0.5 WBCs per microL was observed; a modified protocol was developed to minimize this effect. Parallel analysis of spiked dilution series and evaluations of 39 red cell components filtered through commercial filters indicated good correlation between PCR and standard Nageotte counts in the range of 0.1 to 10 WBCs per microL (r2 = 0.94); only PCR was able to detect residual WBCs in filtrates from prototype 6 log10 WBC-reduction filters. CONCLUSION: This assay should prove useful for the development and quality assurance of increasingly efficient WBC-reduction filters.

Blood Component Removal↗
PubMedDate not supplied

Declining value of alanine aminotransferase in screening of blood donors to prevent posttransfusion hepatitis B and C virus infection. The Retrovirus Epidemiology Donor Study.

BACKGROUND: Since the mid-1980s, blood banks in the United States have screened donors for elevated alanine aminotransferase (ALT) in an effort to prevent posttransfusion hepatitis. The present study was designed to quantitate the residual value of ALT screening following the implementation of hepatitis C virus (HCV) assays. STUDY DESIGN AND METHODS: Two approaches were used. First, a database of 2.3 million donations made by 586,507 volunteer blood donors between 1991 and 1993 was used to compare the incidence of seroconversion to hepatitis B virus (HBV) and HCV marker positivity in donors with elevated ALT values and with normal ALT values. Second, the duration of ALT elevation prior to HBV and HCV seroconversion was determined from 34 well-documented cases of posttransfusion HBV and HCV; elevated-ALT window periods were multiplied by rates of HBV and HCV incidence in donors to project the yield of ALT screening. Predictive value and cost-effectiveness analyses were also performed to compare the value of ALT screening before and after HCV screening was implemented. RESULTS: Both approaches indicate that ALT testing does not detect HBV in the window phase but does currently identify approximately 3 HCV window-phase donations per 1 million donations; this contrasts with ALT detection of approximately 1800 HCV-infectious units per 1 million donations prior to anti-HCV screening. Currently, only 8 in 10,000 donated units with elevated ALT (negative anti-HCV) are infected with HCV. The cost of continued ALT screening was estimated at $7,931,000 per quality-adjusted year of life saved. CONCLUSION: The yield, predictive value, and cost-effectiveness of ALT screening of blood donors have declined dramatically with the implementation of progressively improved anti-HCV assays. ALT screening of volunteer blood donors should be discontinued.

Alanine Transaminase↗
PubMedDate not supplied

Sample suitability for the detection of minor white cell populations (microchimerism) by polymerase chain reaction.

BACKGROUND: There is increasing use of highly sensitive testing with polymerase chain reaction (PCR) to study white cell microchimerism after transfusion and transplantation. This study investigated possible artifactual sources of allogeneic sample contamination before PCR testing. STUDY DESIGN AND METHODS: Quantitative Y-chromosome PCR was used to study microchimerism among transfused patients with sickle cell disease (SCD) and thalassemia by using residual specimens from the clinical laboratory. High levels of circulating male white cells among transfused patients with SCD but not thalassemia led to concern over the artifactual origin of male cells. To investigate, paired specimens were collected from 26 female SCD patients: one specimen underwent processing only for PCR, while the other underwent testing in the clinical laboratory before PCR as a process control. All laboratory instruments were also assessed for their ability to impart male allogeneic cells to aliquots of female blood. RESULTS: Thirty-three (31%) of 107 SCD samples, but 0 of 20 thalassemia samples, gave a high-level PCR signal. One of 26 paired samples that was not exposed to clinical laboratory equipment had low-level PCR positivity while 10 of the 26 became strongly positive after testing on a blood cell analyzer and a reticulocyte analyzer. Sixteen of 32 female samples became positive after reticulocyte analysis, while none became positive after blood cell analysis. Samples from thalassemia patients tested PCR-negative because reticulocyte counts had not been performed. CONCLUSION: Allogeneic cell contamination is common with clinical laboratory equipment. These samples may not be suitable for microchimerism studies. In addition to method controls, process controls should be employed where appropriate.

Anemia, Sickle Cell↗
PubMedDate not supplied

Testing blood donors for HIV: current controversies.

Despite an estimated risk of HIV infection from anti-HIV screened blood transfusions of less than one in 225,000 per unit, there continues to be strong pressure to implement additional donor screening and viral inactivation procedures. Decisions to implement such procedures must be based on analyses that incorporate accurate estimates of residual risk, and data-based projections for the reduction in risk that would result from each measure. Since the residual risk of HIV is primarily due to donations given in the infectious pre-seroconversion window, effort must be directed at: reducing donations by persons in this window; employing tests that narrow the window; and development and implementation of procedures that inactivate viral compartments that predominate during the window. Unfortunately, as the risk of HIV has declined to near-undetectable levels, the challenge of generating appropriate data to evaluate new measures, and thereby support rational policy decisions, has increased inversely. To meet this challenge, we must refine our understanding of the virological characteristics of early HIV seroconversion, and of the types of donors who present in the seroconversion window. Thoughtful application of a thorough understanding of the seroconversion window, in the context of accurate HIV incidence data in the donor settings, should enable us to assure the public of a safe blood supply while resisting inappropriate implementation of unnecessary and usually non-specific procedures.

Blood↗