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PubMed2001

Fourth-generation enzyme-linked immunosorbent assay for the simultaneous detection of human immunodeficiency virus antigen and antibody.

The VIDAS HIV DUO Ultra, a fourth-generation immunoassay under development for the simultaneous detection of human immunodeficiency virus type 1 (HIV-1) p24 antigen and antibodies to HIV-1 and HIV-2, was evaluated. The enzyme-linked fluorescence immunoassay, performed on the automated VIDAS instrument, is claimed to detect early and established HIV infection. The assay was challenged with a total of 2,847 samples that included 74 members of 10 seroconversion panels, 9 p24 antigen-only-reactive members of a panel of group M clades, 503 consecutively collected samples from individuals seeking care in the University of Maryland Medical System, 1,010 samples from U.S. blood donors, 1,141 samples from patients in a high-incidence population in Trinidad, 83 samples from a clinic for sexually transmitted diseases in the Bahamas, 10 confirmed HIV-1 group O samples, and 16 confirmed HIV-2 samples from the Cote d'Ivoire. Reference tests were U.S. Food and Drug Administration-licensed HIV antibody screening, p24 antigen tests, HIV confirmatory assays, and the Roche Diagnostics Amplicor HIV-1 Monitor. The VIDAS HIV DUO Ultra demonstrated 100% sensitivity and 99.5% specificity overall, with a 99.7% specificity in low-risk individuals. The analytical sensitivity, as assessed by seroconversion panels and p24 antigen in samples, was equivalent to the sensitivity of the reference assays used to characterize these panels. The VIDAS HIV DUO Ultra is accurate, offers potential advantages over conventional HIV testing for time and cost savings, has walk-away capability, and correctly identifies both early and established HIV infections.

Enzyme-Linked Immunosorbent Assay↗
PubMed1990

Evaluation of the Phadiatop test in an epidemiological study.

Sera from 204 adult patients with chronic airways obstruction were analysed with the Phadiatop, a new allergosorbent test with a paper disc containing the most relevant inhalant allergens, the PRIST for total IgE determinations, and a panel of seven RAST tests with the common inhalant allergens in The Netherlands as reference. The aim was to evaluate the Phadiatop as screening test in the in vitro diagnostic procedures in an epidemiological setting. The Phadiatop was classified positive or negative according to percentage binding, total IgE was considered elevated at values greater than 100 kU/l and the RAST panel positive when at least one RAST result was class greater than 1. The prevalence of inhalant atopy came to 27.9%. The predictive value of the Phadiatop for a positive RAST panel was 96.4%, and for a negative RAST panel 97.3%. For the PRIST these values were 51.9% and 87.2% respectively. The correlation between the log percentages binding of the Phadiatop and the RAST panel was 0.93. It is concluded that the Phadiatop is a valuable test for the screening of inhalant atopy, and as the percentage binding of the Phadiatop may reflect the degree of sensitization it could also be applied as a quantitative measure especially for epidemiological purposes.

Adult↗
PubMed2026

Parallel Analysis of Repeat Expansions: An Updated Clinical Nanopore Cas9-Targeted Sequencing Workflow for Nanopore R10 Flow Cells.

Hereditary ataxias, caused by expansions of short tandem repeats, are difficult to diagnose using traditional PCR and Southern blot methods, which struggle to detect complex repeat expansions and cannot assess repeat interruptions or methylation. An updated Clinical Nanopore Cas9-Targeted Sequencing workflow is presented for analyzing repeat expansions, now compatible with the Oxford Nanopore Technologies R10 flow cell. The workflow incorporates the Oxford Nanopore Technologies wf-human-variation Epi2Me workflow, including the Straglr tool to analyze base-called reads, ensuring compatibility with past, current, and future sequencing chemistries. It expands the number of genes analyzed from 10 to 27 and introduces new gene panels for ataxia, myopathy, neurodegeneration, and amyotrophic lateral sclerosis/motor neuron disease. Validated with Coriell reference and clinical samples, this method improves the analysis of pathogenic repeat expansions, providing deeper insights into repeat structures while addressing the limitations of traditional approaches. In this work, the use of multiplexing, Flongle flow cells, and single-gene targeting were explored as alternatives to panel-based approaches in the Clinical Nanopore Cas9-Targeted Sequencing workflow, finding that only single-gene targeting provides compatibility and reliable performance.

Journal Article↗
PubMed1997

Characterization of and application of monoclonal antibodies against Rickettsia africae, a newly recognized species of spotted fever group rickettsia.

Rickettsia africae is a newly described species which causes African tick bite fever. Mediterranean spotted fever caused by R. conorii is endemic in the same regions of Africa as tick bite fever, and differentiation of the two syndromes by characterization of their etiological agents is important for epidemiological studies. R. africae and R. conorii are, however, difficult to distinguish, and therefore, our aim was to produce monoclonal antibodies to address this problem. Monoclonal antibodies were produced against R. africae by fusing splenocytes from BALB/C mice immunized with purified rickettsial organisms and SP2/0-Ag14 myeloma cells. A total of 355 hybridomas producing monoclonal antibodies to R. africae were identified by initial screening with six different antigens by microimmunofluorescence assay. A panel of 23 representative monoclonal antibodies were selected and subcloned. This panel was screened with a further 17 different spotted fever group (SFG) rickettsial reference antigens. Of these 23 monoclonal antibodies, 1 cross-reacted with only R. parkeri, whereas the others cross-reacted with more than two different antigens. Immunoblotting indicated that all the monoclonal antibodies were directed against the epitopes on two major high-molecular-mass heat-labile proteins, of which the molecular masses were 128 and 135 kDa, respectively. This monoclonal antibody panel was used successfully to identify R. africae in the blood culture of an infected patient, in infected cells within shell vials, and in infected ticks collected from Africa. Furthermore, the cross-reactivity of each SFG rickettsia with each of these 23 monoclonal antibodies was scored and was used to build a dendrogram of taxonomic relatedness between R. africae and the other SFG rickettsiae on the basis of Jaccard coefficients and unweighted pair group method with arithmetic mean analysis. The relatedness was generally consistent with that obtained by other methods of comparison.

Africa↗
PubMed2004

The long-term stability of amorphous silicon flat panel imaging devices for dosimetry purposes.

This study was carried out to determine the stability of the response of amorphous silicon (a-Si)-flat panel imagers for dosimetry applications. Measurements of the imager's response under reference conditions were performed on a regular basis for four detectors of the same manufacturer. We found that the ambient temperature influenced the dark-field, while the gain of the imager signal was unaffected. Therefore, temperature fluctuations were corrected for by applying a "dynamic" darkfield correction. This correction method also removed the influence of a small, irreversible increase of the dark-field current, which was equal to 0.5% of the dynamic range of the imager per year and was probably caused by mild radiation damage to the a-Si array. By applying a dynamic dark-field correction, excellent stability of the response over the entire panel of all imagers of 0.5% (1 SD) was obtained over an observation period up to 23 months. However, two imagers had to be replaced after several months. For one imager, an image segment stopped functioning, while the image quality of the other imager degraded significantly. We conclude that the tested a-Si EPIDs have a very stable response and are therefore well suited for dosimetry. We recommend, however, applying quality assurance tests dedicated to both imaging and dosimetry.

Calibration↗
PubMed1998

Clinical evaluation of the ASTY colorimetric microdilution panel for antifungal susceptibility testing.

A method using a commercially prepared colorimetric microdilution panel (ASTY; Kyokuto Pharmaceutical Industrial Co., Ltd.) was compared in four different laboratories with the National Committee for Clinical Laboratory Standards (NCCLS) reference microdilution method by testing 802 clinical isolates of Candida spp. (C. albicans, C. glabrata, C. tropicalis, C. parapsilosis, C. krusei, C. lusitaniae, C. guilliermondii, C. lipolytica, C. rugosa, and C. zeylanoides) against amphotericin B, 5-fluorocytosine (5FC), fluconazole, and itraconazole. Reference MIC endpoints were established after 48 h of incubation, and ASTY endpoints were established after 24 and 48 h of incubation. ASTY endpoints were determined to be the time at which the color of the first well changed from red (indicating growth) to purple (indicating growth inhibition) or blue (indicating no growth). Excellent agreement (within 2 dilutions) between the reference and colorimetric MICs was observed. Overall agreement was 93% at 24 h and 96% at 48 h. Agreement ranged from 90% with itraconazole and 5FC to 96% with amphotericin B at 24 h and from 92% with itraconazole to 99% with amphotericin B and 5FC at 48 h. The ASTY colorimetric microdilution panel method appears to be comparable to the NCCLS reference method for testing the susceptibilities of Candida spp. to a variety of antifungal agents.

Amphotericin B↗
PubMed1992

Certification of cholesterol measurements by the National Reference Method Laboratory Network with routine clinical specimens: effects of network laboratory bias and imprecision.

The National Reference Method Laboratory Network has initiated a program to certify clinical laboratory cholesterol measurement performance by using routine clinical specimens. Clinical laboratory and reference laboratory measurements of split samples are used to assess whether the clinical laboratory is meeting the Laboratory Standardization Panel's goals for accuracy and precision. We used a computer-based Monte Carlo simulation model of split-sample proficiency testing to evaluate the certification program and, in particular, to analyze the effects of reference laboratory bias and imprecision. Results of our simulations indicate that the accuracy of the certification program is strongly influenced by reference laboratory bias and less influenced by reference laboratory imprecision. The certification program is potentially highly accurate, but unless reference laboratory bias is tightly controlled, the number of classification errors may limit its utility. Moreover, the decision limit of the certification program needs to be higher than the Laboratory Standardization Panel's goal (3.5% instead of 3.0%) to ensure that an acceptably high proportion of well-performing clinical laboratories can become certified.

Certification↗
PubMed2003

Active control of acoustic reflection, absorption, and transmission using thin panel speakers.

This paper explores the development of thin panels that can be controlled electronically so as to provide surfaces with desired reflection coefficients. Such panels can be used as either perfect reflectors or absorbers. They can also be designed to be transmission blockers that block the propagation of sound. The development of the control system is based on the use of wave separation algorithms that separate incident sound from reflected sound. In order to obtain a desired reflection coefficient, the reflected sound is controlled to appropriate levels. The incident sound is used as an acoustic reference for feedforward control and has the important property of being isolated from the action of the control system speaker. In order to use a panel as a transmission blocker, the acoustic pressure behind the panel is driven to zero. The use of the incident signal as a reference again plays a key role in successfully reducing broadband transmission of sound. The panels themselves are constructed using poster board and small rare-earth actuators. Detailed experimental results are presented showing the efficacy of the algorithms in achieving real-time control of reflection or transmission. The panels are able to effectively block transmission of broadband sound. Practical applications for these panels include enclosures for noisy machinery, noise-absorbing wallpaper, the development of sound walls, and the development of noise-blocking glass windows.

Journal Article↗
PubMed1995

Five new microsatellite polymorphisms at the q21 region of human chromosome 21.

Five clones, containing polymorphic CA-repeat sequences, have been isolated from a specific human chromosome 21 phage library and have been localised to band q21 of chromosome 21 using a somatic cell hybrid panel. These highly repetitive sequences (D21S1263, D21S1264, D21S1415, D21S1417 and D21S1420) have been characterised in the CEPH reference parents and have heterozygosities ranging from 0.30 to 0.81 and an average polymorphism information content (PIC) of 0.62. The relative order of these markers, based on the somatic cell hybrid panel, is cen-D21S1417, D21S1420-D21S1263, D21S1415-D21S1264-tel. The most polymorphic marker (D21S1264) has been included in the chromosome 21 genetic map. They have also been localised in the CEPH/Généthon YAC panel, providing a refined localisation of these polymorphic sequences. These five CA-repeat markers should provide a better characterisation of the q21 region of chromosome 21.

Animals↗
PubMed1999

Comparative evaluation of hepatitis C virus RNA quantitation by branched DNA, NASBA, and monitor assays.

Several studies have shown a relationship between pretreatment hepatitis C virus (HCV) viral load and the response to interferon (IFN) therapy, creating a need for quantitative HCV-RNA assays. Here, we compared three commercial methods: nucleic acid sequence-based amplification NASBA (Organon), branched DNA 2.0 (bDNA) (Chiron), and Monitor (Roche), with reverse-transcription polymerase chain reaction (RT-PCR) as the reference. We assessed sensitivity and reproducibility on a well-characterized panel of sera (EUROHEP), a Chimp Rodney plasma pool, and samples from IFN-treated and -untreated patients with chronic hepatitis C caused by different HCV genotypes. The reproducibility of the NASBA and bDNA methods was slightly better than that of Monitor, especially for genotypes 2 and 4. NASBA had the highest sensitivity (99% vs. 94% and 88% with Monitor and bDNA, respectively), especially for the follow-up of patients on IFN. NASBA gave the highest HCV-RNA concentrations, which were approximately 10-fold more than with the bDNA assay and 100-fold more than with the Monitor kit. The linearity, tested on the chimp Rodney plasma pool, was better with bDNA for high viral load than with NASBA and Monitor, although for low concentration of HCV RNA, bDNA was negative. Pretreatment viral load was lower in patients who had a sustained virological response to IFN, although the bDNA method was not sensitive enough to quantify all pretreatment samples. This study indicates that gene amplification methods (NASBA or Monitor) have better sensitivity than bDNA assays for quantification of HCV RNA in patients with chronic HCV infection, although the bDNA and NASBA methods are more likely to quantify all genotypes. Prospective studies are needed to demonstrate the usefulness of quantitative assays for the follow-up of patients with chronic hepatitis C.

Base Sequence↗
PubMed1991

Linkage mapping of autosomal dominant retinitis pigmentosa (RP1) to the pericentric region of human chromosome 8.

Linkage mapping in a large, seven-generation family with type 2 autosomal dominant retinitis pigmentosa (ADRP) demonstrates linkage between the disease locus (RP1) and DNA markers on the short arm of human chromosome 8. Five markers were most informative for mapping ADRP in this family using two-point linkage analysis. The markers, their maximum lod scores, and recombination distances were ANK1 (ankyrin)--2.0 at 16%; D8S5 (TL11)--5.3 at 17%; D8S87 [a(CA)n repeat]--7.2 at 14%; LPL (lipoprotein lipase)--1.5 at 26%; and PLAT (plasminigen activator, tissue)--10.6 at 7%. Multipoint linkage analysis, using a simplified pedigree structure for the family (which contains 192 individuals and two inbreeding loops), gave a maximum lod score of 12.2 for RP1 at a distance 8.1 cM proximal to PLAT in the pericentric region of the chromosome. Based on linkage data from the CEPH (Paris) reference families and physical mapping information from a somatic cell hybrid panel of chromosome 8 fragments, the most likely order for four of these five loci and the diseases locus is 8pter-LPL-D8S5-D8S87-PLAT-RP1. (The precise location of ANK1 relative to PLAT in this map is not established). The most likely location for RP1 is in the pericentric region of the chromosome. Recently, several families with ADRP with tight linkage to the rhodopsin locus at 3q21-q24 were reported and a number of specific rhodopsin mutations in families with ADRP have since been reported. In other ADRP families, including the one in this study, linkage to rhodopsin has been excluded. Thus mutations at two different loci, at least, have been shown to cause ADRP. There is no remarkable clinical disparity in the expression of disease caused by these different loci.

Base Sequence↗
PubMed2004

European performance evaluations of the ADVIA Centaur infectious disease assays: requirements for performance evaluation according to the European directive on in vitro diagnostics.

The following article reports on newly developed ADVIA Centaur immunoassays (Bayer HealthCare LLC, Diagnostics Division; Tarrytown, NY, USA) for the detection of markers of hepatitis B infection in human serum and plasma. These fully automated assays detect antibodies to hepatitis B surface antigen (anti-HBs), total antibodies to hepatitis B core antigen (anti-HBc Total) and IgM antibodies to hepatitis B core antigen (anti-HBc IgM). The ADVIA Centaur HBV assays employ magnetic particle separation technology with direct chemiluminescence for optimal assay performance. The three ADVIA Centaur HBV assays were tested in extensive performance evaluations at two sites in Europe. Prospectively collected specimens from HBV infected subjects, blood donors, hospitalized/clinical patients and HBV vaccinees were tested under routine laboratory conditions to generate performance data. The studies resulted in the following clinical performance: overall diagnostic specificity > 99.9%, i.e. 100% for ADVIA Centaur Anti-HBs, 100% for ADVIA Centaur HBcIgM and 99.94% for ADVIA Centaur HBc Total. All of the assays showed excellent diagnostic sensitivity, as follows: 99.0% for ADVIA Centaur Anti-HBs, 98.5% for ADVIA Centaur HBcIgM and 100% for ADVIA Centaur HBc Total. Interfering substances and potential cross-reacting samples produced no effects on the results in any of the three ADVIA Centaur HBV assays. Evaluations using HBV seroconversion panels resulted in comparable or better results as compared to the reference assay(s). The performance evaluation data clearly demonstrate that the three ADVIA Centaur HBV assays are specific and sensitive automated immunoassays for the detection of antibodies to hepatitis B virus. Furthermore, these data indicate that assay performance is comparable, if not better, than the performance of currently marketed assays. Additionally, these assays have all of the advantages of being on the ADVIA Centaur immunoassay system including high throughput and full automation. Finally, these data, which had been submitted to the appropriate regulatory agencies (Notified Bodies) in Europe, have resulted in these assays now being CE marked and, thus, being readily available in the European market.

Autoanalysis↗
PubMed2006

Sensitivity of a modified version of the ARCHITECT Anti-HCV test in detecting samples with immunoblot-confirmed, low-level antibody to hepatitis C virus.

BACKGROUND AND OBJECTIVES: Compliance with current regulations regarding the prevention of hepatitis C virus (HCV) transmission in the blood transfusion setting requires the use of sensitive assays for HCV antibody (anti-HCV) detection, which should, ideally, identify any donor having had prior contact with the virus. Therefore, low-level anti-HCV positive blood units should be detected by the screening assays, even those reflecting a past and resolved infection. To assess the sensitivity of two versions of an automated chemiluminescent microparticle immunoassay (CMIA) for anti-HCV screening (ARCHITECT Anti-HCV), 113 single serum samples containing low levels of anti-HCV, assessed by two immunoblot tests, were selected from 3686 samples received for confirmation of HCV infection by a reference laboratory over a 2-year period. MATERIALS AND METHODS: The panel included 17 samples with HCV RNA detected by the polymerase chain reaction (PCR) and 96 PCR negative samples with either positive or indeterminate (anti-Core and anti-NS3 alone) results by immunoblot. RESULTS: All but 13 specimens (100/113, 88.5%) were detected by the current version of the ARCHITECT Anti-HCV assay and 10 additional samples (110/113, 97.3%) tested positive in a modified version of the test. CONCLUSION: The results showed that the modification introduced in the ARCHITECT Anti-HCV assay achieves a significant sensitivity improvement including samples with low-level anti-HCV which are either PCR positive or negative.

Automation↗
PubMed2003

Cutaneous lymphoid hyperplasia: a lymphoproliferative continuum with lymphomatous potential.

Cutaneous lymphoid hyperplasia (CLH) has been proposed to be the benign end of a continuum of lymphoproliferative disorders with cutaneous lymphoma at its malignant extreme. An intermediate condition, known as "clonal CLH," was first recognized by us and shown to be a transitional state capable of eventuating in overt lymphoma. To better determine the prevalence of dominant clonality and risk of lymphoma among CLH cases, we studied the immunohistology and clonality of fresh-frozen samples from 44 CLH patients referred to a multidisciplinary cutaneous lymphoproliferative disorders program. Using a large panel of lymphoid markers, the cases were divided into 38 typical mixed B-cell/T-cell type CLH and 6 T-cell-rich type (T-CLH), the latter containing > 90% T cells. Of the 44 patients, 38 had solitary or localized lesions (4 cases of T-CLH), and 6 had regional/generalized lesions (2 cases of T-CLH). Forty cases were of idiopathic etiology. Suspected etiologies among 4 other cases included mercuric tattoo pigment, doxepin, clozapine, and bacterial infection. Immunoglobulin heavy chain (IgH) and T-cell receptor (TCR)-gamma gene rearrangements (GR) were studied using polymerase chain reaction assays, which are approximately 80% sensitive. Overall, 27 cases (61%) showed clonal CLH: 12 IgH+ (27%; 3 cases of T-CLH); 13 TCR+ (30%; 1 case of T-CLH); and 2 IgH+/TCR+ (4%; neither case was T-CLH). Two cases (4%; 1 case of T-CLH) progressed to cutaneous B-cell lymphoma. Both of these patients presented with regional lesions. Our findings indicate that clonal overgrowth is common in CLH, links CLH to lymphoma, and probably involves both B- and T-cell lineages (although TCR GR by B cells and vice versa could not be ruled out). The high prevalence of dominant clonality in our series may have resulted from the sensitivity of our PCR assays as well as patient selection.

Algorithms↗
PubMed2003

Contemporary management of superficial bladder cancer in the United States: a pattern of care analysis.

OBJECTIVES: To assess the practice preferences among urologists treating superficial bladder cancer in the United States. METHODS: We surveyed 226 urologists using a specially designed survey instrument. The type of practice, number of urologists in group practice, annual volume of patients with bladder cancer, and those treated with intravesical therapy were assessed. We also obtained information on the American Urological Association section and year of graduation from urology residency training. RESULTS: Of the 226 contacted urologists, 105 (46%) returned a completed survey instrument. Seventeen percent were practicing in academic institutions and 63% were in independent community practice. Forty-five percent had graduated from urology training in or before 1985. Thirty-six percent were in small and 37% were in moderate-size groups. Thirty-five percent were treating a moderate number of patients with bladder cancer, and 44% were treating a large number of patients annually. Thirty-two percent had a moderate number and 40% had a large number of patients receiving intravesical therapy annually. Immunotherapy was preferred in patients at high risk of recurrence. Intravesical chemotherapy was preferred by many for immunotherapy failure. The type of practice and year of graduation were the factors most frequently affecting treatment choice. CONCLUSIONS: Practice preferences for the management of superficial bladder cancer are in general agreement with the American Urological Association Bladder Cancer Guidelines Panel recommendations. However, 81% of surveyed urologists were still reluctant to refer patients with high-grade Ta-T1 disease with failure after intravesical immunotherapy twice for more aggressive therapy such as cystectomy or radiotherapy.

Administration, Intravesical↗
PubMed1999

Approach of the US food and nutrition board to daily nutrient requirements: 'a useful basis for the European discussion on risk assessment of nutrients?' Report on a workshop organized by the European Academy of Nutritional Sciences (EANS) and TNO Food and Nutrition Research Institute, 11 December 1998, Brussels.

OBJECTIVE: To discuss the approach of the US Food and Nutrition Board (FNB) to daily nutrient requirements and its relevance for Europe. SETTING: A workshop for experts from academia and regulatory bodies, together with members from the FNB Dietary Reference Intakes Subcommittee on Upper Reference Levels of Intake, and from the B-vitamins Expert panel. The workshop was organised by the European Academy of Nutritional Sciences and TNO Nutrition and Food Research Institute (The Netherlands). CONCLUSIONS: Classical approaches to recommended dietary allowances (RDA) are no longer satisfactory, because they do not take into account newly emerging science with regard to intakes beyond the RDA. There is an urgent need for global harmonisation of criteria used for assessing adequacy of intake and for harmonisation of terminology. For sound advice to consumers, the development of tolerable upper intake levels is necessary. The discussion of principal issues relating to criteria for nutrient adequacy should be pursued on an international level. SPONSORSHIP: Roche Vitamins Europe Ltd, Birsfelden, Switzerland

Europe↗
PubMed1996

The D antigen characteristic of RoHar is a partial D antigen.

The results of testing RoHarr cells with panels of monoclonal anti-D suggest that the D antigen (referred to as DHar) encoded by the haplotype (D)c(e) Rh33 is a partial D antigen. IgM monoclonal anti-D are more efficient than IgG monoclonal anti-D in detecting DHar.DHar expresses some but not all of both epD5 and epD6/7 and appears to lack epD1-epD4, epD8 and epD9.

Epitopes↗