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43 result(s) for "Sheldon, Joanna"
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Standardization of autoantibody testing: a paradigm for serology in rheumatic diseases
Key Points Autoantibody measurement is required for the adequate diagnosis and management of systemic autoimmune rheumatic diseases The advent of new techniques, as well as the increasing number of autoimmune diagnostic laboratories, raises the issues of assay variability and reproducibility As a consequence, harmonization of the available assays is becoming increasingly urgent The availability of suitable reference material for calibration and quality control is emerging as a valuable tool for increasing assay reliability Initiatives for harmonization of testing have been started by several international committees and organizations Autoantibody testing is key for the diagnosis, classification and management of systemic autoimmune rheumatic diseases; however, issues regarding the reproducibility and reliability of these tests currently limit their usefulness. Approaches to harmonize autoantibody tests, including the development of technical guidelines and the availability of suitable reference materials for calibration and quality control, are discussed in this Review. Autoantibody measurement is an excellent tool to confirm the diagnosis of rheumatic autoimmune diseases. Hence, reliability and harmonization of autoantibody testing are essential, but these issues are still a matter of debate. Intrinsic variability in analytes and reagents as well as heterogeneity of the techniques are the main reasons for discrepancies in inter-laboratory variations and reporting of test results. This lack of reliability might be responsible for wrong or missed diagnoses, as well as additional costs due to assay repetition, unnecessary use of confirmatory tests and/or consequent diagnostic investigations. To overcome such issues, the standardization of autoantibody testing requires efforts on all aspects of the assays, including the definition of the analyte, the pre-analytical stages, the calibration method and the reporting of results. As part of such efforts, the availability of suitable reference materials for calibration and quality control would enable the development of a reliable reference system. Strong-positive sera from patients have been used as reference materials in most of the autoantibody assays for rheumatic diseases; however, antigen-affinity-purified immunoglobulin fractions or in some cases reliable monoclonal antibody preparations offer more adequate tools for standardization. Systematic assessments of reference materials are currently underway, and preliminary results appear to be encouraging.
Strategies for Building Reference Standards for Autoantibodies
Producing robust, certified, traceable reference material for autoantibody testing is a vital element in maintaining the validity of results that are generated in the daily clinical laboratory routine. This is a huge challenge because of the high number of variables involved in the detection and measurement of the autoantibodies. The production of such materials is time consuming and needs rigorous attention to detail; this is best achieved by an overarching independent body who will oversee the process in a \"not for profit\" manner. Much effort has been made to build international standards for quantitative and qualitative assays based on monoclonal antibodies, obtained from affinity purification and plasmapheresis. The big challenge is to respect individual differences in immune response to the same antigen. A promising ongoing initiative is the construction of pools with monospecific samples from different individuals.
Characterization of the New Serum Protein Reference Material ERM-DA470k/IFCC: Value Assignment by Immunoassay
The availability of a suitable matrix reference material is essential for standardization of the immunoassays used to measure serum proteins. The earlier serum protein reference material ERM-DA470 (previously called CRM470), certified in 1993, has led to a high degree of harmonization of the measurement results. A new serum protein material has now been prepared and its suitability in term of homogeneity and stability has been verified; after characterization, the material has been certified as ERM-DA470k/IFCC. We characterized the candidate reference material for 14 proteins by applying a protocol that is considered to be a reference measurement procedure, by use of optimized immunoassays. ERM-DA470 was used as a calibrant. For 12 proteins [α(2) macroglobulin (A2M), α(1) acid glycoprotein (orosomucoid, AAG), α(1) antitrypsin (α(1)-protease inhibitor, AAT), albumin (ALB), complement 3c (C3c), complement 4 (C4), haptoglobin (HPT), IgA, IgG, IgM, transferrin (TRF), and transthyretin (TTR)], the results allowed assignment of certified values in ERM-DA470k/IFCC. For CRP, we observed a bias between the lyophilized and liquid frozen materials, and for CER, the distribution of values was too broad. Therefore, these 2 proteins were not certified in the ERM-DA470k/IFCC. Different value transfer procedures were tested (open and closed procedures) and found to provide equivalent results. A new serum protein reference material has been produced, and values have been successfully assigned for 12 proteins.
The Importance of Commutability of Reference Materials Used as Calibrators: The Example of Ceruloplasmin
Different methods for ceruloplasmin tend to give different results in external quality assessment schemes. During the production of the certified reference material ERM-DA470k/IFCC discrepant measurement results were also found for ceruloplasmin measured with different methods, and consequently the protein could not be certified in the material. We performed a commutability study with 30 serum samples and the reference materials ERM-DA470, ERM-DA470k/IFCC, and ERM-DA472/IFCC, using 6 different methods. Data were analyzed according to the CLSI Guideline C53-A to assess whether the reference materials had the same behavior as the serum samples with respect to measurement results obtained with combinations of the methods used. Measurement results from different methods showed a good linear correlation for the serum samples. ERM-DA470 showed marked noncommutability for certain combinations of methods. ERM-DA470k/IFCC and ERM-DA472/IFCC were commutable for more combinations of methods. The lack of commutability of ERM-DA470 for certain combinations of methods correlates with results from the UK National External Quality Assessment Service showing discrepancies between results from these methods. For serum stored in the presence of sodium azide the results from different methods are essentially equivalent. Ceruloplasmin in ERM-DA470 is a fully documented example of a situation in which, due to lack of commutability, the use of a common material for calibration did not lead to harmonization .
Serum α2-HS Glycoprotein Predicts Survival in Patients with Glioblastoma
Background: Glioblastoma, the most common primary brain tumor, has variable prognosis. We aimed to identify serum biomarkers that predict survival of patients with glioblastoma. Methods: In phase 1 (biomarker discovery), SELDI-TOF mass spectra were studied in 200 serum samples from 58 control subjects and 36 patients with grade II astrocytoma, 15 with anaplastic astrocytoma, and 91 with glioblastoma. To identify potential biomarkers, we searched for peptide peaks that changed progressively in size with increasing malignancy. One peak, identified as the B-chain of α2-Heremans-Schmid glycoprotein (AHSG), was less prominent with increasing tumor grade. We therefore investigated AHSG as a survival predictor in glioblastoma. We measured serum AHSG by turbidimetry and determined indices of malignancy, including tumor proliferation (Ki67 immunolabel) and necrosis (tumor lipids on magnetic resonance spectroscopy). In phase 2 (biomarker validation), the prognostic power of AHSG was validated in an independent group of 72 glioblastoma patients. Results: Median survival was longer (51 vs 29 weeks) in glioblastoma patients with normal vs low serum AHSG concentrations (hazard ratio 2.7, 95% CI 1.5–5.0, P <0.001), independent of age and Karnofsky score. Serum AHSG inversely correlated with Ki-67 immunolabeling and tumor lipids. A prognostic index combining serum AHSG with patient age and Karnofsky score separated glioblastoma patients with short (<3 months) and long (>2 years) median survival. The prognostic value of serum AHSG was validated in a different cohort of glioblastoma patients. Conclusions: We conclude that serum AHSG concentration, measured before starting treatment, predicts survival in patients with glioblastoma.
Serum alpha^sub 2^-HS Glycoprotein Predicts Survival in Patients with Glioblastoma
Glioblastoma, the most common primary brain tumor, has variable prognosis. We aimed to identify serum biomarkers that predict survival of patients with glioblastoma. In phase 1 (biomarker discovery), SELDI-TOF mass spectra were studied in 200 serum samples from 58 control subjects and 36 patients with grade II astrocytoma, 15 with anaplastic astrocytoma, and 91 with glioblastoma. To identify potential biomarkers, we searched for peptide peaks that changed progressively in size with increasing malignancy. One peak, identified as the B-chain of α^sub 2^-Heremans-Schmid glycoprotein (AHSG), was less prominent with increasing tumor grade. We therefore investigated AHSG as a survival predictor in glioblastoma. We measured serum AHSG by turbidimetry and determined indices of malignancy, including tumor proliferation (Ki67 immunolabel) and necrosis (tumor lipids on magnetic resonance spectroscopy). In phase 2 (biomarker validation), the prognostic power of AHSG was validated in an independent group of 72 glioblastoma patients. Median survival was longer (51 vs 29 weeks) in glioblastoma patients with normal vs low serum AHSG concentrations (hazard ratio 2.7, 95% CI 1.5-5.0, P <0.001), independent of age and Karnofsky score. Serum AHSG inversely correlated with Ki-67 immunolabeling and tumor lipids. A prognostic index combining serum AHSG with patient age and Karnofsky score separated glioblastoma patients with short (<3 months) and long (>2 years) median survival. The prognostic value of serum AHSG was validated in a different cohort of glioblastoma patients. We conclude that serum AHSG concentration, measured before starting treatment, predicts survival in patients with glioblastoma.
Serum alpha 2-HS glycoprotein predicts survival in patients with glioblastoma
Glioblastoma, the most common primary brain tumor, has variable prognosis. We aimed to identify serum biomarkers that predict survival of patients with glioblastoma. In phase 1 (biomarker discovery), SELDI-TOF mass spectra were studied in 200 serum samples from 58 control subjects and 36 patients with grade II astrocytoma, 15 with anaplastic astrocytoma, and 91 with glioblastoma. To identify potential biomarkers, we searched for peptide peaks that changed progressively in size with increasing malignancy. One peak, identified as the B-chain of alpha 2-Heremans-Schmid glycoprotein (AHSG), was less prominent with increasing tumor grade. We therefore investigated AHSG as a survival predictor in glioblastoma. We measured serum AHSG by turbidimetry and determined indices of malignancy, including tumor proliferation (Ki67 immunolabel) and necrosis (tumor lipids on magnetic resonance spectroscopy). In phase 2 (biomarker validation), the prognostic power of AHSG was validated in an independent group of 72 glioblastoma patients. Median survival was longer (51 vs 29 weeks) in glioblastoma patients with normal vs low serum AHSG concentrations (hazard ratio 2.7, 95% CI 1.5-5.0, P <0.001), independent of age and Karnofsky score. Serum AHSG inversely correlated with Ki-67 immunolabeling and tumor lipids. A prognostic index combining serum AHSG with patient age and Karnofsky score separated glioblastoma patients with short (<3 months) and long (>2 years) median survival. The prognostic value of serum AHSG was validated in a different cohort of glioblastoma patients. We conclude that serum AHSG concentration, measured before starting treatment, predicts survival in patients with glioblastoma.
Massive splenomegaly in tropical West Africa
Causes of massive splenomegaly in malarious areas chronic myeloid leukaemia Gaucher disease haemoglobin SC hairy cell leukaemia hyper-reactive malarial splenomegaly idiopathic and secondary myelofibrosis leishmaniasis (kala-azar) malignant lymphoma portal hypertension thalassaemia major Learning points the commonest causes of massive splenomegaly in the tropics are chronic granulocytic leukaemia, myelofibrosis, portal hypertension, leishmaniasis, haemoglobinopathies, and HMS multiple pathologies and late presentations with gross clinical features are common in tropical practice it is important to make an accurate diagnosis of massive splenomegaly even if no specific treatment is available in order to avoid the inconvenience, expense and toxicity of inappropriate therapies a diagnosis of HMS should be based on specific clinical and laboratory features; it is not a diagnosis 'of exclusion' the clinical features and a simple panel of laboratory tests is usually sufficient to diagnose the common causes of massive splenomegaly in the tropics QUESTION 2 Hyper-reactive malarial splenomegaly (HMS), formerly known as tropical splenomegaly syndrome. Diagnostic criteria for HMS include splenomegaly >=10 cm, elevated IgM, response to antimalarial therapy, and exclusion of underlying lymphoma. 1 Initially, case 1 fulfilled criteria for HMS but immunofixation and immunoselection of her paraprotein demonstrated [mu]-heavy chain with no associated immunoglobulin light chain (figure 2 ) and a diagnosis of [mu]-heavy chain disease was made. [mu]-Heavy chain disease is the least common type of heavy chain disease and was first reported in 1970.