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John Bradley

Publications and source records attributed to John Bradley.

10 recordsLinked to original sources
PubMed2002

Impact of the international program for Quality Assessment and Standardization for Immunological Measures Relevant to HIV/AIDS: QASI.

Measurements of CD4 T-cell levels are essential for the assessment of human immunodeficiency virus (HIV) disease course, clinical staging, epidemiological studies, and decisions regarding prophylactic therapies against opportunistic infection. Until now, only in the industrialized countries was T-cell subset monitoring considered a practical option to assess disease progression. The Quality Assessment and Standardization for Immunological Measures Relevant to HIV/AIDS (QASI) program was established in 1997 to meet performance assessment for immunophenotyping laboratories in countries where such service is not available. The QASI program is provided at no cost to any laboratory in a resource-poor setting that wishes to participate. This report describes the beneficial impact of participation in the QASI program. Carefully selected commercial stabilized whole blood preparations were sent regularly to participating laboratories. Participants reported the T-cell subset values they obtained by flow cytometry. Once the aggregate mean values for the T-cell subsets were established for the shipment, a comprehensive and confidential report was sent to each laboratory. The results from five consecutive shipments were analyzed. The coefficient of variation decreased from 7.2% to 4.7% and from 14.2% to 8.8% for percent and absolute CD4 T-cell counts, respectively. With the implementation of the QASI program using commercial stabilized whole blood specimens, it is possible to reduce interlaboratory error. This study illustrates that a quality assessment program can improve the overall performance of laboratories. Reducing interlaboratory variation can enhance significantly the effectiveness of multicenter HIV vaccine or drug trial evaluation.

Acquired Immunodeficiency Syndrome↗
PubMed2002

Evaluation of stabilized blood cell products as candidate preparations for quality assessment programs for CD4 T-cell counting.

BACKGROUND: Exceptionally robust cell preparations are needed for quality assessment programs (QAPs) such as the International Program for Quality Assessment and Standardization for Immunological Measures (QASI) relevant to HIV/AIDS. A suitable product must withstand environmental stress related to transportation for a minimum of 6 days. The two objectives of this study are (1) to evaluate the performance of various commercial preparations with multicenter participation and (2) to evaluate the robustness of stabilized blood cell products. METHODS: Phase 1: The performance of stabilized blood cell products was evaluated in a multicenter QAP utilizing various staining procedures and flow cytometers. Absolute cell enumeration was achieved using single-platform T-cell subset methodology. Phase 2: The robustness of stabilized blood cell products was evaluated by monitoring T-cell subset values from samples stored at 4 degrees C, 22 degrees C, and 37 degrees C for up to 10 days. RESULTS: The largest interlaboratory variation in both absolute and relative T-cell values was 16% in samples with CD4 levels > or =400 cells per microliter and 21% in samples with CD4 levels <400 cells per microliter. Six preparations retained their phenotypic expression for 7 days at 4 degrees C and 22 degrees C. However, only two preparations remained stable for 4 days at 37 degrees C. CONCLUSION: Some stabilized cell preparations are more robust and therefore more suitable for quality assessment purposes.

CD3 Complex↗
PubMed2002

Subcellular redistribution of la/SSB autoantigen during physiologic apoptosis in the fetal mouse heart and conduction system: a clue to the pathogenesis of congenital heart block.

OBJECTIVE: In isolated congenital heart block, the mechanism by which maternal autoantibodies target the intracellular components of the Ro/La RNP complex is unclear. Previous studies have demonstrated that cultured fetal cardiac myocytes rendered apoptotic bind antibodies to 48-kd La/SSB. This study further investigated the subcellular distribution of the La antigen during apoptosis in the fetal mouse heart and conduction system. METHODS: The atrioventricular (AV) node, AV bundle, and sinoatrial (SA) node were identified in serial sections prepared from paraffin blocks of normal mouse fetuses on days 15, 17, and 19 of gestation. Apoptosis was detected by TUNEL assay. Under confocal microscopy, fluorescent labeling of fragmented DNA in apoptotic cells was assessed by TUNEL, and La protein localization was visualized simultaneously using a murine monoclonal antibody or affinity-purified human polyclonal anti-La antibodies. RESULTS: Apoptotic cells were detected in and at the periphery of the AV and SA nodes as well as in the fetal heart valve insertions and working myocardium. In contrast, no apoptosis was detected in the adult heart AV node or surrounding myocardium. As expected, the La antigen was predominantly immunolocalized to the nucleus in nonapoptotic cells. However, apoptotic cells showed a marked reduction of nuclear La and redistribution of La to the cytoplasm. High-resolution confocal microscopy revealed that in cells that had undergone apoptosis, La antigen asymmetrically clustered near the surface of TUNEL-positive nuclei and apoptotic bodies. CONCLUSION: These data provide the first in vivo demonstration of the subcellular translocation of La autoantigen during apoptosis in the fetal heart and the conduction system under physiologic conditions. This observation supports the hypothesis that subcellular redistribution of La in the normally developing heart facilitates the binding of cognate maternal antibodies and subsequent tissue damage.

Animals↗
PubMed2002

Anti-La/SSB antibodies transported across the placenta bind apoptotic cells in fetal organs targeted in neonatal lupus.

OBJECTIVE: To determine whether La and/or Ro epitopes on apoptotic cells in fetal organs that are targeted in neonatal lupus syndrome (NLS) are accessible for binding by autoantibodies in vivo, we traced the fate of transplacental autoantibodies in a murine passive transfer model. METHODS: Pregnant mice at day 15 of gestation (E15) were injected intraperitoneally with human anti-Ro/La-positive sera or control sera, and transplacental transfer of human autoantibodies was tested by enzyme-linked immunosorbent assay with recombinant antigens. Multiple cryostat sections at the level of the heart of E17 fetuses were visualized simultaneously for human IgG binding and apoptosis (TUNEL) under confocal microscopy. Serial paraffin sections of E17 and E19 fetuses were examined for histologic evidence of inflammation. RESULTS: Human IgG anti-52-kd Ro, anti-60-kd Ro, and anti-La autoantibodies were transported efficiently into the fetal circulation. Human IgG-apoptotic cell complexes were detected in the heart (atrial trabeculae and atrioventricular node), skin, liver, and newly forming bone of fetuses from mothers injected with anti-Ro/La sera but not control sera. The IgG binding was fetal-specific and organ-specific; transplacental autoantibodies did not bind to apoptotic cells in the fetal thymus, lung, brain, or gut. The complexes were not associated with an inflammatory reaction. Injection of mothers with affinity-purified anti-La autoantibodies (but not anti-Ro/La Ig depleted of anti-La) revealed an identical location of IgG binding to apoptotic cells in the fetuses. CONCLUSION: This is the first study to demonstrate that transplacental anti-La autoantibodies bind specifically to apoptotic cells in selected fetal organs in vivo, similar to the organ involvement in NLS. We hypothesize that additional factors are required to promote proinflammatory clearance of IgG-apoptotic cell complexes and subsequent tissue damage.

Animals↗
PubMed2002

An evaluation of specificity in activity-dependent gene expression in neurons.

Activity-dependent synaptic modification must occur specifically to preserve the large information storage capacity of neurons. Since long-term changes in synaptic strength require gene expression and new protein synthesis we consider the role that gene expression plays in the specificity of synaptic modification. Ca2+ influx is essential for transducing synaptic activity into gene expression. Different temporal profiles of increased global Ca2+ and different types of Ca2+ channel have been demonstrated to produce different effects in the nucleus. It is possible therefore that synaptic activity may produce different programs of gene expression which may in turn control specific long-term changes in synaptic strength. We review recent data which suggest that the spatial properties of Ca2+ influx may provide a mechanism for the selective activation of molecules which signal to the nucleus. In particular, we describe data which suggests that Ca2+ channels may function in signal complexes at the synapse to propagate signals that contribute to distinct nuclear responses.

Animals↗
PubMed2002

Erdheim-Chester disease: case report, PCR-based analysis of clonality, and review of literature.

Erdheim-Chester disease (ECD) is a rare, distinct clinicopathologic entity with nearly pathognomonic radiographic features. The lesions consist of lipid-storing CD68 (+), CD1a (-) non-Langerhans' cell histiocytes, either localized to the bone or involving multiple organ systems in the body. Whether these histiocytic proliferations represent monoclonal neoplastic populations or are part of a polyclonal reactive process is unclear. We present a case report of ECD in a 35-year-old African-American woman with a progressive course over 6 years. We investigated the clonality of the histiocytes using the HUMARA assay on paraffin-embedded tissue sections but did not find any evidence that these cells represent a monoclonal population. In this report, the characteristics of ECD are reviewed, the genetic basis of the HUMARA assay is discussed, and our results in the context of other clonality investigations reported in the literature to date are summarized.

Adult↗
PubMed2002

Quinolone treatment for pediatric bacterial meningitis: a comparative study of trovafloxacin and ceftriaxone with or without vancomycin.

BACKGROUND: Trovafloxacin is a new fluoroquinolone that exhibits good penetration into the central nervous system and excellent antimicrobial activity against common meningeal pathogens, including beta-lactam-resistant pneumococci. PURPOSE AND DESIGN: A multicenter, randomized clinical trial was conducted in children with bacterial meningitis to compare the safety and efficacy of trovafloxacin with that of ceftriaxone with or without vancomycin therapy. RESULTS: A total of 311 patients, ages 3 months to 12 years, were enrolled, of whom 203 were fully evaluable, 108 treated with trovafloxacin and 95 with the conventional regimen. Both groups were comparable with regard to baseline characteristics: age; cerebrospinal fluid findings; use of dexamethasone; history of seizures; and etiologic agents. No significant differences between trovafloxacin and the comparator, respectively, were detected in any of the following outcome measures: clinical success at 5 to 7 weeks after treatment (79% vs. 81%); deaths (2% vs. 3%); seizures after enrollment (22% vs. 21%); and severe sequelae (14% vs. 14%). Only 4 of 284 children developed joint abnormalities up to 6 months after treatment, 1 (0.9%) child received trovafloxacin and 3 (3.1%) received the comparator regimen. None of the evaluable patients experienced significant abnormalities of liver function during treatment. One nonevaluable patient who received trovafloxacin for 5 days and ceftriaxone for 11 days was readmitted to the hospital with hepatitis of unknown etiology 1 day after discharge. The episode resolved with liver function tests returning to normal within 2 months. CONCLUSIONS: We conclude that trovafloxacin is an effective antibiotic for treatment of pediatric bacterial meningitis. These favorable results support further evaluation of fluoroquinolone therapy for children with meningitis or other serious bacterial infections.

Anti-Infective Agents↗
PubMed2001

Introduction.

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Journal Article↗
PubMed2000

Cellular and subcellular distribution of polycystin-2, the protein product of the PKD2 gene.

Mutations in the PKD1 and PKD2 genes account for 85 and 15% of cases of autosomal dominant polycystic kidney disease, respectively. Polycystin-2, the product of the PKD2 gene, is predicted to be an integral membrane protein with homology to a family of voltage-activated Ca(2+) channels. In vitro studies suggest that it may interact with polycystin-1, the PKD1 gene product, via coiled-coil domains present in their C-terminal domains. In this study, the cellular and subcellular distribution of polycystin-2 is defined and compared with polycystin-1. A panel of rabbit polyclonal antisera was raised against polycystin-2 and shown to recognize a single band consistent with polycystin-2 in multiple tissues and cell lines by immunoprecipitation and Western blotting. Immunostaining of human and murine renal tissues demonstrated widespread and developmentally regulated expression of polycytin-2, with highest levels in the kidney in the thick ascending limbs of the loop of Henle and the distal convoluted tubule. In contrast, polycystin-1 expression, while localizing to the same tubular segments, was highest in the collecting ducts. Immunohistochemical staining and immunofluorescence microscopy localized polycystin-2 to the basolateral plasma membrane of kidney tubular epithelial cells compared with the junctional localization of polycystin-1. Differences in the developmental, cellular, and subcellular expression of polycystin-1 and polycystin-2 suggest that they may be able to function independently of each other in addition to a potential in vivo interaction via their C-termini.

Animals↗