The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Ake Lernmark - One of the best experts on this subject based on the ideXlab platform.
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Neuropeptide Y autoantibodies in patients with long-term type 1 and type 2 diabetes and neuropathy.
Journal of diabetes and its complications, 2013Co-Authors: Hanna Skärstrand, Ake Lernmark, Lars B. Dahlin, Fariba Vaziri-saniAbstract:Aims: The neurotransmitter Neuropeptide Y (NPY) was previously reported as a minor autoantigen in newly diagnosed type 1 diabetes (T1D) patients. The single nucleotide polymorphism at rs16139 (T1128C, L7P) in the NPY gene was associated with an increased risk for the development of type 2 diabetes (T2D). We aimed to develop a Radiobinding Assay for NPY-L (Leucine) and NPY-P (Proline) autoantibodies (A) to study the levels and the association with other islet autoantibodies and neuropathy. Methods: Autoantibodies against NPY-L, NPY-P, ZnT8, GAD65 and IA-2 were studied in T1D (n=48) and T2D (n=26) patients with duration up to 42 and 31years. A subgroup of T1D (n=32) patients re-examined, 5-8years after first visit, was tested for peripheral (Z-score) and autonomic neuropathy (E/I ratio). Results: NPY-LA and NPY-PA were detected in 23% and 19% in T1D (p
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A novel triple mix Radiobinding Assay for the three ZnT8 (ZnT8-RWQ) autoantibody variants in children with newly diagnosed diabetes.
Journal of immunological methods, 2011Co-Authors: Fariba Vaziri-sani, Ahmed J Delli, Bengt Lindblad, Annelie Carlsson, Gun Forsander, Sten A Ivarsson, Johnny Ludvigsson, Claude Marcus, Helena Elding-larsson, Ake LernmarkAbstract:Autoantibodies against the zinc transporter 8 (ZnT8A) are common in type 1 diabetes (T1D). ZnT8A analyses are complicated by the fact that there are three variants of the autoantigen at amino acid position 325 representing ZnT8-R (Arginine), ZnT8-W (Tryptophan) and ZnT8-Q (Glutamin). The aims of the study were: 1) to develop an autoantigen triple mix Radio-Binding Assay (RBA) for ZnT8A; 2) to identify the individual ZnT8-R,-W,-QA reactivity and 3) to validate the triple mix ZnT8A RBA in children with newly diagnosed T1D. Serum samples were obtained from 2664 (56% males, n=1436) patients in the Swedish nationwide Better Diabetes Diagnosis (BDD) study representing patients with T1D (97%, n=2582), T2D (1.7%, n=46), MODY (1.0%, n=28) and secondary diabetes (0.3%, n=8). cDNA coding for the C-terminal end of each variant was prepared by site-directed mutagenesis and subcloned into a high efficiency in vitro transcription translation vector. The ZnT8 variants were labeled with 35S-methionine and used in a standard RBA separating free from autoantibody-bound autoantigen with Protein A-Sepharose. ZnT8-TripleA was detected in 1678 (65%) patients with T1D, 4 (9%) T2D, 3 (11%) MODY and in none (0%) of the patients with secondary diabetes. Among the T1D patients ZnT8-RA was detected in 1351 (52%) patients, ZnT8-WA in 1209 (47%) and ZnT8-QA in 790 (31%) demonstrating that 1661 (64%) had one or several ZnT8A. The ZnT8-TripleA Assay showed a false positive rate of 1.9% (n=49). Only 1.2% (n=32) of the T1D patients were false negative for ZnT8-TripleA compared to 0/46 (0%) of the T2D patients. The precision (intra Assay CV) and reproducibility (inter Assay CV) of the ZnT8-TripleA Assay did not differ from the RBA of the individual ZnT8 variants. We conclude that the ZnT8-TripleA Assay had low false positive and false negative rates. The ZnT8-TripleA Assay would therefore be highly suitable not only to analyze patient with newly diagnosed diabetes but also for screening the general population since this Assay demonstrated high sensitivity and very high specificity. Copyright © 2011 Elsevier B.V. All rights reserved.
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A novel triple mix Radiobinding Assay for the three ZnT8 (ZnT8-RWQ) autoantibody variants in children with newly diagnosed diabetes
Journal of Immunological Methods, 2011Co-Authors: Fariba Vaziri-sani, Ahmed J Delli, Bengt Lindblad, Annelie Carlsson, Gun Forsander, Sten A Ivarsson, Johnny Ludvigsson, Claude Marcus, Helena Elding-larsson, Ake LernmarkAbstract:Background and aims: Autoantibodies against the zinc transporter 8 (ZnT8A) are common in type 1 diabetes (T1D). ZnT8A analyses are complicated by the fact that there are three variants of the autoa ...
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High diagnostic accuracy for idiopathic Addison’s disease with a sensitive Radiobinding Assay for autoantibodies against recombinant human 21-hydroxylase
The Journal of clinical endocrinology and metabolism, 1995Co-Authors: Alberto Falorni, Andrej Nikoshkov, S Laureti, E Grenbäck, Anna-lena Hulting, G Casucci, F Santeusanio, P Brunetti, Holger Luthman, Ake LernmarkAbstract:Autoantibodies against 21-hydroxylase (P450c21) are common in idiopathic autoimmune Addison's disease. In the present work, we have developed a sensitive Radiobinding Assay using in vitro translated recombinant human 35S-P450c21. Levels of P450c21 antibodies (P450c21-Ab) were expressed as a relative index (P450c21 index) using a P450c21-Ab positive Addisonian serum and two antibody-negative healthy sera as positive and negative standards in healthy individuals. The upper level of normal was the mean + 3 SD. Positivity for P450c21-Ab was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of immunoprecipitated 35S-P450c21. In 38 Addisonian patients, P450c21-Ab were found in 24/28 (86%) idiopathic, 0/5 post-tuberculosis, 0/3 adrenoleukodystrophy, and 0/2 post-adrenalectomy sera. Among healthy individuals, 1/70 (1.4%) were positive. The P450c21 index, as an estimate of P450c21-Ab levels, correlated inversely with the duration of idiopathic Addison's disease (r = -0.527;...
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high diagnostic accuracy for idiopathic addison s disease with a sensitive Radiobinding Assay for autoantibodies against recombinant human 21 hydroxylase
The Journal of Clinical Endocrinology and Metabolism, 1995Co-Authors: Alberto Falorni, Andrej Nikoshkov, S Laureti, E Grenbäck, Anna-lena Hulting, G Casucci, F Santeusanio, P Brunetti, Holger Luthman, Ake LernmarkAbstract:Autoantibodies against 21-hydroxylase (P450c21) are common in idiopathic autoimmune Addison's disease. In the present work, we have developed a sensitive Radiobinding Assay using in vitro translated recombinant human 35S-P450c21. Levels of P450c21 antibodies (P450c21-Ab) were expressed as a relative index (P450c21 index) using a P450c21-Ab positive Addisonian serum and two antibody-negative healthy sera as positive and negative standards in healthy individuals. The upper level of normal was the mean + 3 SD. Positivity for P450c21-Ab was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of immunoprecipitated 35S-P450c21. In 38 Addisonian patients, P450c21-Ab were found in 24/28 (86%) idiopathic, 0/5 post-tuberculosis, 0/3 adrenoleukodystrophy, and 0/2 post-adrenalectomy sera. Among healthy individuals, 1/70 (1.4%) were positive. The P450c21 index, as an estimate of P450c21-Ab levels, correlated inversely with the duration of idiopathic Addison's disease (r = -0.527;...
Vito Lampasona - One of the best experts on this subject based on the ideXlab platform.
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islet autoantibody standardization program 2018 workshop interlaboratory comparison of glutamic acid decarboxylase autoantibody Assay performance
Clinical Chemistry, 2019Co-Authors: Vito Lampasona, Alistair J. K. Williams, William E. Winter, Beena Akolkar, Peter Achenbach, David Pittman, M Schlosser, Participating LaboratoriesAbstract:Background: The Islet Autoantibody Standardization Program (IASP) aims to improve the performance of immunoAssays measuring type 1 diabetes (T1D)-associated autoantibodies and the concordance of results among laboratories. IASP organizes international interlaboratory Assay comparison studies in which blinded serum samples are distributed to participating laboratories, followed by centralized collection and analysis of results, providing participants with an unbiased comparative assessment. In this report, we describe the results of glutamic acid decarboxylase autoantibody (GADA) Assays presented in the IASP 2018 workshop. Methods: In May 2018, IASP distributed to participants uniquely coded sera from 43 new-onset T1D patients, 7 multiple autoantibody-positive nondiabetic individuals, and 90 blood donors. Results were analyzed for the following metrics: sensitivity, specificity, accuracy, area under the ROC curve (ROC-AUC), partial ROC-AUC at 95% specificity (pAUC95), and concordance of qualitative and quantitative results. Results: Thirty-seven laboratories submitted results from a total of 48 different GADA Assays adopting 9 different formats. The median ROC-AUC and pAUC95 of all Assays were 0.87 [interquartile range (IQR), 0.83–0.89] and 0.036 (IQR, 0.032–0.039), respectively. Large differences in pAUC95 (range, 0.001–0.0411) were observed across Assays. Of formats widely adopted, bridge ELISAs showed the best median pAUC95 (0.039; range, 0.036–0.041). Conclusions: Several novel Assay formats submitted to this study showed heterogeneous performance. In 2018, the majority of the best performing GADA immunoAssays consisted of novel or established nonradioactive tests that proved on a par or superior to the Radiobinding Assay, the previous gold standard Assay format for GADA measurement.
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Reactivity to N-Terminally Truncated GAD65(96–585) Identifies GAD Autoantibodies That Are More Closely Associated With Diabetes Progression in Relatives of Patients With Type 1 Diabetes
Diabetes, 2015Co-Authors: Alistair J. K. Williams, Vito Lampasona, Rebecca Wyatt, Cristina Brigatti, Kathleen M. Gillespie, Polly J. Bingley, Peter AchenbachAbstract:GAD autoantibodies (GADAs) identify individuals at increased risk of developing type 1 diabetes, but many people currently found to be GADA positive are unlikely to progress to clinical disease. More specific GADA Assays are therefore needed. Recent international workshops have shown that the reactivity of sera from healthy donors varies according to Assay type and indicated that the use of N-terminally truncated GAD65 radiolabels in GADA Radiobinding Assays is associated with higher specificity. To determine whether a Radiobinding Assay using radiolabeled GAD65(96–585) identified individuals who are at higher risk of developing diabetes, samples from recent-onset patients and GADA-positive first-degree relatives participating in the Bart’s-Oxford type 1 diabetes family study were reAssayed with full-length or N-terminally truncated GAD using the National Institute of Diabetes and Digestive and Kidney Diseases harmonized protocol. The sensitivity in patients was the same with both labels, but fewer relatives retested positive with truncated GAD. Among relatives who progressed to diabetes, similar proportions were found to be GADA positive when tested with either label, but because of their higher specificity the cumulative risk of diabetes was higher in those with autoantibodies to GAD65(96–585). Autoantibodies to GAD65(96–585) in relatives are more closely associated with diabetes risk than those to full-length GAD, suggesting that Assays using N-terminally truncated GAD should be used to select participants for intervention trials.
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Detection of antibodies directed to the N-terminal region of GAD is dependent on Assay format and contributes to differences in the specificity of GAD autoantibody Assays for type 1 diabetes
Diabetes, 2015Co-Authors: Alistair J. K. Williams, Vito Lampasona, Michael Schlosser, Patricia W. Mueller, David L. Pittman, William E. Winter, Beena Akolkar, Rebecca Wyatt, Cristina Brigatti, Stephanie KrauseAbstract:GAD autoantibodies (GADAs) are sensitive markers of islet autoimmunity and type 1 diabetes. They form the basis of robust prediction models and are widely used for the recruitment of subjects at high risk of type 1 diabetes to prevention trials. However, GADAs are also found in many individuals at low risk of diabetes progression. To identify the sources of diabetes-irrelevant GADA reactivity, we analyzed data from the 2009 and 2010 Diabetes Autoantibody Standardization Program GADA workshop and found that binding of healthy control sera varied according to Assay type. The characterization of control sera found positive by Radiobinding Assay (RBA), but negative by ELISA, showed that many of these sera reacted to epitopes in the N-terminal region of the molecule. This finding prompted development of an N-terminally truncated GAD65 radiolabel, 35S-GAD65(96–585), which improved the performance of most GADA RBAs participating in an Islet Autoantibody Standardization Program GADA substudy. These detailed workshop comparisons have identified a source of disease-irrelevant signals in GADA RBAs and suggest that N-terminally truncated GAD labels will enable more specific measurement of GADAs in type 1 diabetes.
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Radiobinding Assay for detecting autoantibodies to single epitopes.
Journal of immunological methods, 2008Co-Authors: Vito Lampasona, Cristina Belloni, Sandra Piquer, Sara Bonicchio, Roberto Furlan, Ezio BonifacioAbstract:Abstract Autoantibodies, a hallmark of autoimmune disease, are directed against diverse antigens and epitopes. This diversity aids in characterising disease progression and identifying disease-associated autoantibodies. Here we aimed to develop a sensitive Assay to detect and quantify epitope-specific autoantibodies. We generated constructs to integrate known peptide epitopes into the TrxA protein, and used these to in vitro synthesize radio-labelled proteins for a Radiobinding Assay (RBA). This Assay was first validated with an animal model using mice immunized with the MOG40–55 peptide. Using type 1 diabetes-associated protein tyrosine phosphatase-like autoantigen IA-2 as a human model, we expressed IA-2609–621, IA-2619–631, or IA-2609–631 peptide in the TrxA construct and used the RBA to test sera from 113 patients with type 1 diabetes and 87 controls. Antibodies were detected to the IA-2609–631 epitope in 37 of 113 patient sera and one control; 17 sera were reactive to the IA-2609–621 (JM1) epitope, and 16 to the IA-2619–631 (JM2) epitope. Interestingly, a novel third epitope (JM3) was identified in 7 sera that reacted to IA-2609–631 but not the JM1 and JM2 sub-specificities. An ELISA using IA-2609–631 was less sensitive than the RBA, as it detected only some of the JM1 and JM3 antibody positive sera and none of the JM2. Mutagenesis of single IA-2609–631 amino acids in combination with the RBA showed that antibodies to JM2 and JM3 were highly diverse in their specific residue requirements. Our strategy using in vitro synthesized antigens and the RBA was thus a highly sensitive and versatile method to identify epitopes and quantify epitope-specific antibodies.
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Similar low frequency of anti-MOG IgG and IgM in MS patients and healthy subjects
Neurology, 2004Co-Authors: Vito Lampasona, Ezio Bonifacio, Roberto Furlan, Diego Franciotta, S. Zanaboni, Raffaella Fazio, G. Comi, Gianvito MartinoAbstract:The authors used a liquid-phase Radiobinding Assay to measure serum anti-myelin oligodendrocyte protein (MOG) immunoglobulin (Ig) G in 87 patients with multiple sclerosis (MS), in 12 patients with encephalomyelitis, and in 47 healthy subjects. Anti-MOG IgM was determined in samples obtained at onset from 40 of 87 patients with MS and in control subjects. The frequency of positive samples with low titers of anti-MOG IgG (≤5.7%) and IgM (≤8.3%) was similar in all the groups and subgroups. Binding competition experiments showed that these antibodies had low affinity. Anti-MOG antibodies are not disease specific.
Alistair J. K. Williams - One of the best experts on this subject based on the ideXlab platform.
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islet autoantibody standardization program 2018 workshop interlaboratory comparison of glutamic acid decarboxylase autoantibody Assay performance
Clinical Chemistry, 2019Co-Authors: Vito Lampasona, Alistair J. K. Williams, William E. Winter, Beena Akolkar, Peter Achenbach, David Pittman, M Schlosser, Participating LaboratoriesAbstract:Background: The Islet Autoantibody Standardization Program (IASP) aims to improve the performance of immunoAssays measuring type 1 diabetes (T1D)-associated autoantibodies and the concordance of results among laboratories. IASP organizes international interlaboratory Assay comparison studies in which blinded serum samples are distributed to participating laboratories, followed by centralized collection and analysis of results, providing participants with an unbiased comparative assessment. In this report, we describe the results of glutamic acid decarboxylase autoantibody (GADA) Assays presented in the IASP 2018 workshop. Methods: In May 2018, IASP distributed to participants uniquely coded sera from 43 new-onset T1D patients, 7 multiple autoantibody-positive nondiabetic individuals, and 90 blood donors. Results were analyzed for the following metrics: sensitivity, specificity, accuracy, area under the ROC curve (ROC-AUC), partial ROC-AUC at 95% specificity (pAUC95), and concordance of qualitative and quantitative results. Results: Thirty-seven laboratories submitted results from a total of 48 different GADA Assays adopting 9 different formats. The median ROC-AUC and pAUC95 of all Assays were 0.87 [interquartile range (IQR), 0.83–0.89] and 0.036 (IQR, 0.032–0.039), respectively. Large differences in pAUC95 (range, 0.001–0.0411) were observed across Assays. Of formats widely adopted, bridge ELISAs showed the best median pAUC95 (0.039; range, 0.036–0.041). Conclusions: Several novel Assay formats submitted to this study showed heterogeneous performance. In 2018, the majority of the best performing GADA immunoAssays consisted of novel or established nonradioactive tests that proved on a par or superior to the Radiobinding Assay, the previous gold standard Assay format for GADA measurement.
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The Core Cysteines, (C909) of Islet Antigen-2 and (C945) of Islet Antigen-2b, Are Crucial to Autoantibody Binding
2016Co-Authors: Alistair J. K. WilliamsAbstract:Cysteines are thought integral to conformational epitopes of islet antigen-2 (IA-2) autoantibodies (IA-2A), possibly through disul-fide bond formation. We therefore investigated which cysteines are critical to IA-2A binding in patients with newly diagnosed type 1 diabetes. All 10 cysteines in the intracellular domain of IA-2 were modified to serine by site-directed mutagenesis, and the effects of these changes on autoantibody binding in comparison with wild-type control were investigated by Radiobinding Assay. Mutation of the protein tyrosine phosphatase (PTP) core cysteine (C909) in IA-2 caused large reductions in autoantibody binding. In contrast, little or no reduction in binding was seen following substitution of the other cysteines. Modification of the core cysteine (C945) in IA-2b also greatly reduced autoantibody bind-ing. Lysine substitution of glutamate-836 in IA-2 or glutamate-872 in IA-2b resulted in modest reductions in binding and identifie
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Reactivity to N-Terminally Truncated GAD65(96–585) Identifies GAD Autoantibodies That Are More Closely Associated With Diabetes Progression in Relatives of Patients With Type 1 Diabetes
Diabetes, 2015Co-Authors: Alistair J. K. Williams, Vito Lampasona, Rebecca Wyatt, Cristina Brigatti, Kathleen M. Gillespie, Polly J. Bingley, Peter AchenbachAbstract:GAD autoantibodies (GADAs) identify individuals at increased risk of developing type 1 diabetes, but many people currently found to be GADA positive are unlikely to progress to clinical disease. More specific GADA Assays are therefore needed. Recent international workshops have shown that the reactivity of sera from healthy donors varies according to Assay type and indicated that the use of N-terminally truncated GAD65 radiolabels in GADA Radiobinding Assays is associated with higher specificity. To determine whether a Radiobinding Assay using radiolabeled GAD65(96–585) identified individuals who are at higher risk of developing diabetes, samples from recent-onset patients and GADA-positive first-degree relatives participating in the Bart’s-Oxford type 1 diabetes family study were reAssayed with full-length or N-terminally truncated GAD using the National Institute of Diabetes and Digestive and Kidney Diseases harmonized protocol. The sensitivity in patients was the same with both labels, but fewer relatives retested positive with truncated GAD. Among relatives who progressed to diabetes, similar proportions were found to be GADA positive when tested with either label, but because of their higher specificity the cumulative risk of diabetes was higher in those with autoantibodies to GAD65(96–585). Autoantibodies to GAD65(96–585) in relatives are more closely associated with diabetes risk than those to full-length GAD, suggesting that Assays using N-terminally truncated GAD should be used to select participants for intervention trials.
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Detection of antibodies directed to the N-terminal region of GAD is dependent on Assay format and contributes to differences in the specificity of GAD autoantibody Assays for type 1 diabetes
Diabetes, 2015Co-Authors: Alistair J. K. Williams, Vito Lampasona, Michael Schlosser, Patricia W. Mueller, David L. Pittman, William E. Winter, Beena Akolkar, Rebecca Wyatt, Cristina Brigatti, Stephanie KrauseAbstract:GAD autoantibodies (GADAs) are sensitive markers of islet autoimmunity and type 1 diabetes. They form the basis of robust prediction models and are widely used for the recruitment of subjects at high risk of type 1 diabetes to prevention trials. However, GADAs are also found in many individuals at low risk of diabetes progression. To identify the sources of diabetes-irrelevant GADA reactivity, we analyzed data from the 2009 and 2010 Diabetes Autoantibody Standardization Program GADA workshop and found that binding of healthy control sera varied according to Assay type. The characterization of control sera found positive by Radiobinding Assay (RBA), but negative by ELISA, showed that many of these sera reacted to epitopes in the N-terminal region of the molecule. This finding prompted development of an N-terminally truncated GAD65 radiolabel, 35S-GAD65(96–585), which improved the performance of most GADA RBAs participating in an Islet Autoantibody Standardization Program GADA substudy. These detailed workshop comparisons have identified a source of disease-irrelevant signals in GADA RBAs and suggest that N-terminally truncated GAD labels will enable more specific measurement of GADAs in type 1 diabetes.
Peter Achenbach - One of the best experts on this subject based on the ideXlab platform.
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islet autoantibody standardization program 2018 workshop interlaboratory comparison of glutamic acid decarboxylase autoantibody Assay performance
Clinical Chemistry, 2019Co-Authors: Vito Lampasona, Alistair J. K. Williams, William E. Winter, Beena Akolkar, Peter Achenbach, David Pittman, M Schlosser, Participating LaboratoriesAbstract:Background: The Islet Autoantibody Standardization Program (IASP) aims to improve the performance of immunoAssays measuring type 1 diabetes (T1D)-associated autoantibodies and the concordance of results among laboratories. IASP organizes international interlaboratory Assay comparison studies in which blinded serum samples are distributed to participating laboratories, followed by centralized collection and analysis of results, providing participants with an unbiased comparative assessment. In this report, we describe the results of glutamic acid decarboxylase autoantibody (GADA) Assays presented in the IASP 2018 workshop. Methods: In May 2018, IASP distributed to participants uniquely coded sera from 43 new-onset T1D patients, 7 multiple autoantibody-positive nondiabetic individuals, and 90 blood donors. Results were analyzed for the following metrics: sensitivity, specificity, accuracy, area under the ROC curve (ROC-AUC), partial ROC-AUC at 95% specificity (pAUC95), and concordance of qualitative and quantitative results. Results: Thirty-seven laboratories submitted results from a total of 48 different GADA Assays adopting 9 different formats. The median ROC-AUC and pAUC95 of all Assays were 0.87 [interquartile range (IQR), 0.83–0.89] and 0.036 (IQR, 0.032–0.039), respectively. Large differences in pAUC95 (range, 0.001–0.0411) were observed across Assays. Of formats widely adopted, bridge ELISAs showed the best median pAUC95 (0.039; range, 0.036–0.041). Conclusions: Several novel Assay formats submitted to this study showed heterogeneous performance. In 2018, the majority of the best performing GADA immunoAssays consisted of novel or established nonradioactive tests that proved on a par or superior to the Radiobinding Assay, the previous gold standard Assay format for GADA measurement.
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Reactivity to N-Terminally Truncated GAD65(96–585) Identifies GAD Autoantibodies That Are More Closely Associated With Diabetes Progression in Relatives of Patients With Type 1 Diabetes
Diabetes, 2015Co-Authors: Alistair J. K. Williams, Vito Lampasona, Rebecca Wyatt, Cristina Brigatti, Kathleen M. Gillespie, Polly J. Bingley, Peter AchenbachAbstract:GAD autoantibodies (GADAs) identify individuals at increased risk of developing type 1 diabetes, but many people currently found to be GADA positive are unlikely to progress to clinical disease. More specific GADA Assays are therefore needed. Recent international workshops have shown that the reactivity of sera from healthy donors varies according to Assay type and indicated that the use of N-terminally truncated GAD65 radiolabels in GADA Radiobinding Assays is associated with higher specificity. To determine whether a Radiobinding Assay using radiolabeled GAD65(96–585) identified individuals who are at higher risk of developing diabetes, samples from recent-onset patients and GADA-positive first-degree relatives participating in the Bart’s-Oxford type 1 diabetes family study were reAssayed with full-length or N-terminally truncated GAD using the National Institute of Diabetes and Digestive and Kidney Diseases harmonized protocol. The sensitivity in patients was the same with both labels, but fewer relatives retested positive with truncated GAD. Among relatives who progressed to diabetes, similar proportions were found to be GADA positive when tested with either label, but because of their higher specificity the cumulative risk of diabetes was higher in those with autoantibodies to GAD65(96–585). Autoantibodies to GAD65(96–585) in relatives are more closely associated with diabetes risk than those to full-length GAD, suggesting that Assays using N-terminally truncated GAD should be used to select participants for intervention trials.
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Mature high-affinity immune responses to (pro)insulin anticipate the autoimmune cascade that leads to type 1 diabetes
The Journal of clinical investigation, 2004Co-Authors: Peter Achenbach, Heike E. Naserke, Anette-g. Ziegler, Kerstin Koczwara, A. Knopff, Ezio BonifacioAbstract:Children at risk for type 1 diabetes can develop early insulin autoantibodies (IAAs). Many, but not all, of these children subsequently develop multiple islet autoantibodies and diabetes. To determine whether disease progression is reflected by autoantibody maturity, IAA affinity was measured by competitive Radiobinding Assay in first and subsequent IAA-positive samples from children followed from birth in the BABYDIAB cohort. IAA affinity in first positive samples ranged from less than 106 l/mol to more than 1011 l/mol. High affinity was associated with HLA DRB1*04, young age of IAA appearance, and subsequent progression to multiple islet autoantibodies or type 1 diabetes. IAA affinity in multiple antibody–positive children was on average 100-fold higher than in children who remained single IAA positive or became autoantibody negative. All high-affinity IAAs required conservation of human insulin A chain residues 8–13 and were reactive with proinsulin. In contrast, most lower-affinity IAAs were dependent on COOH-terminal B chain residues and did not bind proinsulin. These data are consistent with the concept that type 1 diabetes is associated with sustained early exposure to (pro)insulin in the context of HLA DR4 and show that high-affinity proinsulin-reactive IAAs identify children with the highest diabetes risk.
Fariba Vaziri-sani - One of the best experts on this subject based on the ideXlab platform.
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Neuropeptide Y autoantibodies in patients with long-term type 1 and type 2 diabetes and neuropathy.
Journal of diabetes and its complications, 2013Co-Authors: Hanna Skärstrand, Ake Lernmark, Lars B. Dahlin, Fariba Vaziri-saniAbstract:Aims: The neurotransmitter Neuropeptide Y (NPY) was previously reported as a minor autoantigen in newly diagnosed type 1 diabetes (T1D) patients. The single nucleotide polymorphism at rs16139 (T1128C, L7P) in the NPY gene was associated with an increased risk for the development of type 2 diabetes (T2D). We aimed to develop a Radiobinding Assay for NPY-L (Leucine) and NPY-P (Proline) autoantibodies (A) to study the levels and the association with other islet autoantibodies and neuropathy. Methods: Autoantibodies against NPY-L, NPY-P, ZnT8, GAD65 and IA-2 were studied in T1D (n=48) and T2D (n=26) patients with duration up to 42 and 31years. A subgroup of T1D (n=32) patients re-examined, 5-8years after first visit, was tested for peripheral (Z-score) and autonomic neuropathy (E/I ratio). Results: NPY-LA and NPY-PA were detected in 23% and 19% in T1D (p
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A novel triple mix Radiobinding Assay for the three ZnT8 (ZnT8-RWQ) autoantibody variants in children with newly diagnosed diabetes.
Journal of immunological methods, 2011Co-Authors: Fariba Vaziri-sani, Ahmed J Delli, Bengt Lindblad, Annelie Carlsson, Gun Forsander, Sten A Ivarsson, Johnny Ludvigsson, Claude Marcus, Helena Elding-larsson, Ake LernmarkAbstract:Autoantibodies against the zinc transporter 8 (ZnT8A) are common in type 1 diabetes (T1D). ZnT8A analyses are complicated by the fact that there are three variants of the autoantigen at amino acid position 325 representing ZnT8-R (Arginine), ZnT8-W (Tryptophan) and ZnT8-Q (Glutamin). The aims of the study were: 1) to develop an autoantigen triple mix Radio-Binding Assay (RBA) for ZnT8A; 2) to identify the individual ZnT8-R,-W,-QA reactivity and 3) to validate the triple mix ZnT8A RBA in children with newly diagnosed T1D. Serum samples were obtained from 2664 (56% males, n=1436) patients in the Swedish nationwide Better Diabetes Diagnosis (BDD) study representing patients with T1D (97%, n=2582), T2D (1.7%, n=46), MODY (1.0%, n=28) and secondary diabetes (0.3%, n=8). cDNA coding for the C-terminal end of each variant was prepared by site-directed mutagenesis and subcloned into a high efficiency in vitro transcription translation vector. The ZnT8 variants were labeled with 35S-methionine and used in a standard RBA separating free from autoantibody-bound autoantigen with Protein A-Sepharose. ZnT8-TripleA was detected in 1678 (65%) patients with T1D, 4 (9%) T2D, 3 (11%) MODY and in none (0%) of the patients with secondary diabetes. Among the T1D patients ZnT8-RA was detected in 1351 (52%) patients, ZnT8-WA in 1209 (47%) and ZnT8-QA in 790 (31%) demonstrating that 1661 (64%) had one or several ZnT8A. The ZnT8-TripleA Assay showed a false positive rate of 1.9% (n=49). Only 1.2% (n=32) of the T1D patients were false negative for ZnT8-TripleA compared to 0/46 (0%) of the T2D patients. The precision (intra Assay CV) and reproducibility (inter Assay CV) of the ZnT8-TripleA Assay did not differ from the RBA of the individual ZnT8 variants. We conclude that the ZnT8-TripleA Assay had low false positive and false negative rates. The ZnT8-TripleA Assay would therefore be highly suitable not only to analyze patient with newly diagnosed diabetes but also for screening the general population since this Assay demonstrated high sensitivity and very high specificity. Copyright © 2011 Elsevier B.V. All rights reserved.
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A novel triple mix Radiobinding Assay for the three ZnT8 (ZnT8-RWQ) autoantibody variants in children with newly diagnosed diabetes
Journal of Immunological Methods, 2011Co-Authors: Fariba Vaziri-sani, Ahmed J Delli, Bengt Lindblad, Annelie Carlsson, Gun Forsander, Sten A Ivarsson, Johnny Ludvigsson, Claude Marcus, Helena Elding-larsson, Ake LernmarkAbstract:Background and aims: Autoantibodies against the zinc transporter 8 (ZnT8A) are common in type 1 diabetes (T1D). ZnT8A analyses are complicated by the fact that there are three variants of the autoa ...