| 1. |
- Lernmark, Å, et al.
(författare)
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Heterogeneity of islet pathology in two infants with recent onset diabetes mellitus
- 1995
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Ingår i: Virchows Archiv. - 0945-6317. ; 425:6, s. 631-640
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms by which the beta cells of pancreatic islets are destroyed in insulin-dependent diabetes mellitus (IDDM) are poorly understood. In this report the pancreatic histo- and immunopathology of two children, both HLA-DR 3/4, DQ 2/8 positive and who both died from cerebral oedema within a day of clinical diagnosis of IDDM, were investigated. Patient 1, a 14-month-old girl, had a 4-week history of polydipsia and polyuria. Patient 2, a 3-year-old boy, had 2 days of illness. Both patients had a similarly severe loss of insulin cells but differed markedly as to the extent of lymphocytic islet infiltration (insulitis). Apart from insulitis, marked islet macrophage infiltration was demonstrated in both patients with the HAM-56 monoclonal antibody. Neither patient showed aberrant expression of HLA class II antigens on insulin-immunoreactive cells, but allele-specific HLA-DQ8 expression was evident on endothelial cells. Glutamic acid decarboxylase immunoreactivity was detected in both insulin- and glucagon-immunoreactive cells. It is concluded that the heterogeneity of islet pathology, especially insulitis, may reflect different dynamics and extent rather than different pathomechanisms of immune destruction of islets in IDDM.
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| 2. |
- Sanjeevi, C. B., et al.
(författare)
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Polymorphic amino acid variations in HLA-DQ are associated with systematic physical property changes and occurrence of IDDM
- 1995
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 44:1, s. 125-131
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Tidskriftsartikel (refereegranskat)abstract
- The association between human leukocyte antigen (HLA) insulin-dependent diabetes was studied in a large population-based investigation using genotyping of 425 new-onset patients, 0-14 years of age, and 367 matched control subjects. As many as 97% of patients compared with 75% of control subjects were positive for one or several of DQA1*0301, DQA1*0501, DQB1*0302, or DQB1*0201. Asp-57 DQB was present among 28% of patients, indicating that this residue alone does not confer protection. Combining Asp- 57 DQB1 with either Arg-52 DQA1 or Leu-69 DQA1 did not explain susceptibility or protection either. DQA1*0301-DQB1*0302 (DQS) and DQA1*0301-DQB1*0301 (DQ7) are identical except for four amino acid substitutions in the β- chain, but DQ8 was positively (odds ratio 8.07; P < 0.001) and DQ7 negatively (odds ratio 0.38; P < 0.001) associated with the disease. Molecular modeling was used to determine whether physicochemical properties such as steric factors and surface electrostatic potentials also differ in a systematic way for various DQ molecules. Amino acids were substituted systematically at the four polymorphic sites, and the solvent-accessible surfaces and electrostatic potentials were computed for each molecule. Dramatic alterations in electrostatic potential were seen for double substitutions at position 45 (G45E) and 57 (A57D) of DQB1. The variation of physicochemical properties due to polymorphic substitutions may be significant to the mechanism of HLA-DQ association with insulin-dependent diabetes, via the effect these property variations have on peptide antigen binding selectivity and subsequent interactions with specific T-cell receptors.
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