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Biomedical subjects

M P Busch

Publications and source records attributed to M P Busch.

At least 55 records · Page 3Linked to original sources
PubMed2000

Lookback on donors who are repeatedly reactive on first-generation hepatitis C virus assays:justification and rational implementation.

BACKGROUND: The purpose of this study was to explore strategies to minimize the number of unwarranted consignee notifications resulting from hepatitis C virus (HCV) first-generation (single-antigen) enzyme immunoassay (EIA 1.0) targeted lookback. STUDY DESIGN AND METHOD: The four blood centers participating in this study contributed data on 3753 HCV EIA 1.0-repeatably reactive (RR) donations. The analysis focused on 1) statistical evaluation of HCV EIA 1.0 signal-to-cutoff (S/CO) ratios versus HCV second-generation recombinant immunoblot assay (RIBA 2.0) interpretation from all participating blood centers and 2) RNA testing using transcription-mediated amplification on all HCV EIA 1.0 RR/RIBA 2. 0-positive or -indeterminate specimens and a subset of RIBA 2. 0-negative donations for which specimens were available. RESULTS: Analysis of HCV EIA 1.0 S/CO ratios versus RIBA 2.0 indicated that 1180 (89%) of 1326 RIBA 2.0-positive specimens had an S/CO ratio >2. 5, while 146 (11%) had a ratio </=2.5. In contrast, of 2253 RIBA 2. 0-negative specimens, 299 (13%) had an S/CO ratio >2.5, while 1954 (87%) had a ratio </=2.5. Of 248 HCV EIA 1.0-RR/RIBA 2.0-positive samples with stored specimens available for additional testing, 198 (80%) were HCV RNA positive; 15 (7.5%) of these specimens had an S/CO ratio </=2.5, while 183 (92%) had a ratio >2.5. HCV RNA was detected in only 2 (1.5%) of 137 HCV EIA 1.0-RR/RIBA 2.0-negative specimens: 1 of these 2 specimens had an S/CO >2.5, while the other had an S/CO </=2.5. CONCLUSION: A highly significant (<0.0001) correlation was found between the S/CO ratio on HCV EIA 1.0- and RIBA 2.0-positive or -negative results. An S/CO ratio >2.5 yielded an 89- percent sensitivity for RIBA 2.0-positive specimens, and donations with an S/CO ratio >2.5 had a 75-percent probability of being RIBA 2.0 positive. A policy recommendation to use the S/CO ratio to triage lookback would prevent unwarranted notification of 87 percent of recipients of blood from RIBA 2.0-negative donors and would result in a failure to notify only 5 to 10 percent of recipients potentially exposed to infectious units.

Blood Donors↗
PubMed2000

Absence of evidence of infection with divergent primate T-lymphotropic viruses in United States blood donors who have seroindeterminate HTLV test results.

BACKGROUND: Recent identification of divergent simian or primate T-lymphotropic viruses (STLVs; PTLVs) in bonobos (formerly called pygmy chimpanzees; Pan paniscus; viruses: STLVpan-p and STLVpp1664) and a baboon (Papio hamadryas; viruses: STLVph969 or PTLV-L) have raised the possibility of human infection with these viruses. Divergent PTLV-infected primate sera show p24 bands on HTLV-I Western blots (WBs). It was investigated whether infection by divergent PTLV-like viruses could explain a subset of United States blood donors who reacted on HTLV-I EIAs and had indeterminate HTLV-I WBs with p24 bands. STUDY DESIGN AND METHODS: Epidemiologic characteristics of 1889 donors with HTLV-I-indeterminate WBs were compared to those of donors with confirmed retrovirus infections (393 with HIV, 201 with HTLV-I, 513 with HTLV-II) and 1.6 million donors with nonreactive screening tests. To directly probe for infection with divergent PTLVs, 2 HTLV-I-indeterminate donors born in Africa and 269 representative non-African-born donors with p24 bands on HTLV-I WBs (previously shown to be negative for HTLV-I and -II DNA by PCR) were selected for PTLV PCR analysis. DNA from peripheral blood MNC samples was tested for a proviral tax sequence by PCR using generic primers that amplify HTLV-I, HTLV-II, and the divergent PTLVs. Amplified tax sequences were detected by Southern blot hybridization to a (32)P-labeled generic PTLV probe. PCR-positive samples could then be typed by hybridization with virus-specific internal probes that differentiate HTLV-I, HTLV-II, PTLV-L, and STLVpan-p. RESULTS: In the epidemiologic analysis, HTLV-indeterminate status was independently associated with age of at least 25 years (OR = 2.19; 95% CI, 1.93-2.49), black (OR = 3.27; 95% CI, 2.90-3.67) or Hispanic (OR = 1.82; 95% CI, 1.52-2.16) race or ethnicity, and donation at one blood center (Baltimore) (OR = 1. 30; 95% CI, 1.11-1.53). None of the 271 HTLV-I WB-indeterminate samples tested positive by generic PTLV PCR analysis. CONCLUSION: Although the epidemiologic data suggest the possibility of undiagnosed HTLV-I, HTLV-II, or a cross-reactive virus such as PTLV among older, black, and Hispanic blood donors, the PCR data do not support the presence of divergent PTLV infection among US blood donors with HTLV-I-indeterminate results.

Animals↗
PubMed2000

False-negative testing errors in routine viral marker screening of blood donors. For the Retrovirus Epidemiology Donor Study.

BACKGROUND: The contribution of testing errors to the risk of virus transmission by transfusion depends on the rate of false-negative testing errors and the prevalence of infected seropositive donations. Although the false-negative testing error rate has been estimated at 0.1 to 1 percent on the basis of proficiency studies, it has not previously been measured in routine donor screening. STUDY DESIGN AND METHODS: A 1991 to 1995 database containing 5,153,153 donations from 1.5 x 10(6) donors (including autologous donors) was searched to identify donors who tested seropositive for HIV, HCV, HTLV-I or II and who attempted subsequent donations. The false-negative rate in routinely screened follow-up donations was determined, and false-negative cases were investigated to identify the cause. RESULTS: Subsequent donations (n = 2015) by 1224 donors with confirmed-positive results were identified. Eleven (0.5%) of these donations did not react in EIA. Ten of the 11 false-negative cases were attributable to borderline-reactive donations. On subsequent donations, there were borderline-nonreactive results on HTLV-I (2 cases), first-generation HCV (5 cases), and second-generation HCV (3 cases) EIAs. The final case was strongly reactive for HCV in a second-generation EIA on two donations (signal-to-cutoff [S:C] ratio >3.5), followed by a baseline nonreactive result on a third donation (S:C = 0.05). CONCLUSION: False-negative testing results occur infrequently during routine infectious-disease donor screening. Although most false-negative results occurred with borderline-reactive HTLV-II samples and/or early-generation HCV EIAs, frank technical errors (e.g., sample mixup or failure to add sample to EIA well) also occur at a low rate (0.05%; 95% CI, 0-1.5%). Process enhancements designed to reduce errors (e.g., enhanced automation of data management and testing systems and process controls for EIAs) are warranted to detect and prevent false-negative results.

Blood Donors↗
PubMed2000

Assessment of donor T-cell function in cellular blood components by the CD69 induction assay: effects of storage, gamma radiation, and photochemical treatment.

BACKGROUND: Functional donor T-lymphocytes in blood components may cause a variety of transfusion complications. A flow cytometric assay based on the measurement of induced CD69 expression may be an alternative to cell proliferation methods in determining the functional status of these cells in blood components. STUDY DESIGN AND METHODS: Seven units of whole blood, RBCs, and platelet concentrates (PCs) were stored under blood bank conditions. Half of 3 PCs each were gamma-radiated or treated with UVA+psoralen; the other half served as controls. Samples were analyzed for phorbolester-induced expression of CD69 as an indicator of cell responsiveness and for exclusion of propidium iodide as a measure of cell membrane integrity and viability. RESULTS: CD69 inducibility and propidium iodide exclusion decreased exponentially (half-life, 3. 3 and 8.1 days, respectively) during cold blood storage. Irradiation and UVA+psoralen treatment of PCs immediately reduced CD69 inducibility to 21 percent (controls, 82%; p = 0.004) and 12 percent (controls, 95%; p = 0.0008), respectively. The proportion of cells capable of propidium iodide exclusion was similar in treated samples and controls, but it declined faster in the treated samples during subsequent storage. CONCLUSION: Flow cytometric measurement of CD69 induction can be adapted to provide quantitative assessment of T-cell function in blood components. Results obtained by the CD69 assay are in general agreement with those previously reported by use of proliferation methods; the assay may be useful for special applications in transfusion medicine.

Antigens, CD↗
PubMed2000

Performance of second- and third-generation RIBAs for confirmation of third-generation HCV EIA-reactive blood donations. Retrovirus Epidemiology Donor Study.

BACKGROUND: Licensure of an enhanced HCV screening assay (HCV 3.0 EIA) without concurrent licensure of a complementary supplemental assay (i.e., RIBA HCV 3.0 strip immunoblot assay [RIBA-3]) decoupled screening and supplemental testing. In March 1998, the FDA Center for Biologics Evaluation and Research (CBER) recommended the use of RIBA-3 on RIBA HCV 2.0 strip immunoblot assay (RIBA-2)-indeterminate units screened with HCV EIA 3.0. STUDY DESIGN AND METHODS: The sensitivity of RIBA-2 and RIBA-3 was compared in tests on HCV 3.0 EIA-repeatably reactive (RR) units identified immediately after the implementation of HCV 3.0 EIA screening. Two protocols were evaluated: parallel testing of HCV 3.0 EIA-RR units by RIBA-2 and RIBA-3 and reflex testing of HCV 3.0 EIA-RR and RIBA-3-confirmed-positive units by RIBA-2. All specimens with discordant RIBA-2 and RIBA-3 results and a representative sampling with concordant RIBA results were tested by PCR. RESULTS: In the parallel testing protocol, 99,777 donations were screened, with 245 HCV 3.0 EIA-RR specimens included in the study. Of 166 RIBA-2-positive samples, 165 tested positive in RIBA-3 (1 sample reacted to the control superoxide dismutase antigen in RIBA-3). Thirty-two (74%) of 43 RIBA-2-indeterminate specimens and 4 (11%) of 36 RIBA-2-negative specimens tested positive in RIBA-3. HCV RNA was identified in 5 (16%) of 32 RIBA-2-indeterminate/RIBA-3-positive donations, as well as in 26 (70%) of 37 concordant RIBA-2/RIBA-3-positive donations. In the reflex testing protocol, 292,459 donations were screened, with 709 HCV 3.0 EIA-RR specimens included in the study. RIBA-3 testing yielded 517 (73%) positive specimens, of which 50 (9.7%) tested indeterminate and 15 (2.9%) tested negative in RIBA-2. Among the RIBA-discordant specimens, 10 (20%) RIBA-2-indeterminate specimens and 1 (7%) RIBA-2-negative specimens tested positive in PCR; in comparison, 60 (77%) of 78 concordant RIBA-2/RIBA-3-positive units tested positive in PCR. CONCLUSIONS: RIBA-3 is significantly more sensitive than RIBA-2 in testing of HCV 3.0 EIA-screened donations. During the review process of this manuscript, the FDA licensed the RIBA-3 test.

Blood Donors↗
PubMed2000

Surveillance of HIV-1 genetic subtypesand diversity in the US blood supply.

BACKGROUND: Recent reports of variant (non-subtype B) HIV infections in US populations have raised concerns about the sensitivity of subtype B virus-based donor screening and diagnostic assays. This study was designed to determine the prevalence and genetic diversity of HIV subtypes in US blood donors over the last two decades. STUDY DESIGN AND METHODS: Three groups were studied: hemophiliacs infected by clotting factor concentrates in the early 1980s (n = 49), blood donors retrospectively identified as being seropositive in 1985 (n = 97), and blood donors identified as seropositive between 1993 and 1996 (n = 405). Subtype assignment was based primarily on heteroduplex mobility analysis (HMA) of HIV-1 env, with DNA sequence confirmation of selected specimens. HIV peptide-based EIA serotyping was used to rule out HIV-2 and group O infections and to serotype HMA-refractory specimens. RESULTS: Of 551 specimens, 535 (97%) were assigned subtypes; 532 (99%) of these were subtype B. Three postscreening donations (1%) were assigned non-B subtypes (2 A, 1 C). Two of these three donors were born in Africa; the third was born in the United States and reported no risk factors other than heterosexual activity. HMA distribution plots showed an increase in env diversity among HIV-1 group B strains over time. CONCLUSION: The results support the need for continued surveillance of HIV subtype diversity and ongoing validation of the sensitivity of HIV diagnostic assays to non-B subtype infections.

Blood Donors↗
PubMed2000

The risks of transfusion-transmitted infection: direct estimation and mathematical modelling.

Direct measurement of the risk of transfusion-transmitted infection (TTI) is practical and accurate only if the level of risk is high. Historically, studies that established frozen repositories of transfusion recipient and/or blood donor samples were important in establishing the risk of many TTI agents, including the human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV). However, given the current very low risk of TTI, mathematical modelling is necessary to estimate the magnitude of such a risk. For agents for which routine blood donor screening is performed, most of this risk comes from transfusion of units collected in the window period between donor infection and a positive blood screening assay. The incidence/window period model has been used to estimate the magnitude of such risks (of the order of 1:100 000 to 1:1 000 000) and for predicting the extent of risk reduction that can be expected with implementation of new tests. Direct estimation and mathematical modelling approaches are both important tools for future assessment of potential, new or emerging TTI agents.

Blood Donors↗
PubMed2000

Microchimerism does not induce tolerance after in utero transplantation and may lead to the development of alloreactivity.

In utero transplantation is a new technology that may provide non-toxic treatment for congenital disorders. However, a decade of research on in utero transplantation has demonstrated a low degree of chimerism and tolerance in small and large animal models as well as in human beings. We hypothesized that if large numbers of purified stem cells/progenitors were injected, a higher degree of tolerance would be induced. We have performed a 2-year experiment designed to study chimerism and tolerance after in utero transplantation with large numbers of cytokine-recruited C-kit+ cells. Chimerism in the blood and tissues was tested through the lifespan of the animals, and in vitro immunologic assays were performed at the end of life. C-kit+ cells obtained from the peripheral blood of C57BL/6 mice were injected intraperitoneally into 12- to 13-day-old Balb/c murine fetuses. The injected populations contained 5% to 20% of Sca-1+ and 1% to 5% of CD3+ cells. Twenty-three percent of mice that received transplants showed circulating donor cells in the blood, and 7% to 14% showed donor cells in the tissues. The percent of donor cells in the blood and tissues was low (<0.01%). Timing of injection or cell dose did not affect chimerism or tolerance. Fifty percent (13 of 26) showed accelerated skin graft rejection and 5 of 26 (19%) had prolonged acceptance as compared with control mice not receiving transplants in utero. All mice that rejected skin grafts showed significantly increased natural killer function as compared with the mice with delayed graft acceptance. Fifty percent of tested recipient mice showed reactivity against donor cells in the cytotoxicity assay, which could be related to the prenatal sensitization. We conclude that microchimerism does not lead to the induction of a high degree tolerance after in utero transplantation and instead may lead to the development of alloreactivity to donor cells.

Animals↗
PubMed2000

Evaluation of the safety of Rh immunoglobulin by monitoring viral markers among Rh-negative female blood donors.

BACKGROUND AND OBJECTIVES: Although immunoglobulin (Ig) preparations including RhIg have been noted for their record of safety, recent reports of hepatitis C virus (HCV) transmission by some Ig preparations have raised concern. This analysis examined the safety of RhIg manufactured in the US by comparing the prevalence and incidence of viral markers in Rh-negative and Rh-positive female blood donors. MATERIALS AND METHODS: Demographic and viral marker data were analyzed for allogeneic donations collected from female donors of childbearing age (17-49 years of age) from April 1992 to May 1996. Prevalence and incidence rates were calculated for HCV, human immunodeficiency virus (HIV), and hepatitis B surface antigen (HBsAg). RESULTS: Of the 624,939 female donors included in the study, 96,355 (15.4%) were Rh-negative and 528,584 (84.6%) Rh-positive. There were no significant differences in the prevalence of HCV and HIV between Rh-negative and Rh-positive female donors. HBsAg prevalence was significantly higher among non-white compared to white donors. Following implementation of the more sensitive EIA 2.0 screening test for HCV in April 1992, prevalence and incidence rates declined over time at similar rates for Rh-negative and Rh-positive female donors. CONCLUSIONS: Rh-negative female donors had similar prevalence and incidence rates for most viral markers compared to Rh-positive female donors. This analysis supports the historical safety of RhIg.

Adolescent↗
PubMed1999

Detection of early HIV infection and estimation of incidence using a sensitive/less-sensitive enzyme immunoassay testing strategy at anonymous counseling and testing sites in San Francisco.

Timely estimates of HIV incidence are needed to monitor the epidemic and target primary prevention but have been difficult to obtain. We applied a sensitive/ less-sensitive (S/LS) enzyme immunoassay (EIA) testing strategy to stored HIV-positive sera (N = 452) to identify early infections, estimate incidence, and characterize correlates of recent seroconversion among persons seeking anonymous HIV testing in San Francisco from 1996 to 1998 (N = 21,292). Sera positive on a sensitive EIA but negative on a less-sensitive EIA were classified as early HIV infections; sera positive on both EIA were classified as long standing. Seventy-nine sera were from people with early HIV infection. Estimated HIV incidence was 1.1% per year (95% confidence interval [CI], 0.68%-1.6%) overall and 1.9% per year (95% CI, 1.2%-3.0%) among men who have sex with men (MSM). Early HIV infection among MSM was associated with injection drug use, unprotected receptive anal sex, and multiple sex partners in the previous year. No temporal trend in HIV incidence was noted over the study period. The S/LS strategy provides a practical public health tool to identify early HIV infection and estimate HIV incidence in a variety of study designs and settings.

Adult↗
PubMed1999

HIV type 1 tat gene heteroduplex mobility assay as a tool to establish epidemiologic relationships among HIV type 1-infected individuals.

Molecular biology techniques are increasingly used to study the molecular epidemiology of infectious diseases. Most of these methods are expensive and labor-intensive. The human immunodeficiency virus (HIV) has substantial genomic variation, such that HIVs from different individuals are genetically diverse, although mutation rates differ for distinct regions of the genome. Most studies of HIV linkage and molecular evolution have focused on env or gag regions. We show that heteroduplex mobility analysis of the first exon of the HIV tat gene provides a simple, rapid, inexpensive, and reliable discriminatory tool for the molecular differentiation of shared versus distinct HIV-1 quasispecies when epidemiologic relations need to be defined. tat, as a relatively conserved region, appears to be a better region than the more variable env region to establish HIV-1 epidemiological linkages.

DNA, Viral↗
PubMed1999

Survival of donor leukocyte subpopulations in immunocompetent transfusion recipients: frequent long-term microchimerism in severe trauma patients.

We recently reported detection of a transient increase in circulating donor leukocytes (WBCs) in immunocompetent recipients 3 to 5 days posttransfusion (tx) (Blood 85:1207, 1995). We have now characterized survival kinetics of specific donor WBC subsets in additional tx populations. Eight female elective surgery patients (pts) were sampled pre-tx and on days 1, 3, 5, 7, and 14 post-tx. Ten female trauma pts transfused with a total of 4 to 18 U of relatively fresh red blood cells were sampled up to 1.5 years post-tx. WBC subsets from frozen whole blood were isolated using CD4, CD8 (T cell), CD15 (myeloid), and CD19 (B cell) antibody-coated magnetic beads. Donor WBCs were counted by quantitative polymerase chain reaction (PCR) of male-specific sex determining region (SRY) sequences. PCR HLA typing and mixed leukocyte reaction (MLR) between recipient and donor WBCs were performed on two of the trauma tx recipients who had long-term chimerism of donor cells post-tx. In 6 of 8 female surgery pts, circulating CD4(+) male donor cells peaked at day 3 or 5 (0.01 to 1 cell/microL), followed by clearance by day 14. In 7 of 10 female trauma pts, we observed multilineage persistence of male donor WBCs (CD4, CD8, CD15, CD19) for 6 months to 1.5 years post-tx at concentrations of 10 to 100 cells/microL. In 2 trauma recipients studied, MLR showed no, or very low, response to WBC of the single donor implicated as the source of microchimerism by HLA typing. Establishment of long-term multilineage chimerism in trauma recipients is probably caused by engraftment of donor stem cells and mutual tolerance between recipient and donor leukocytes. A better understanding of factors determining clearance versus chimerism of transfused leukocytes is critical to prevention of alloimmunization and transfusion-induced graft-versus-host disease, and, potentially, to induction of tolerance for transplantation.

Accidents, Traffic↗