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Idiopathic normal pressure hydrocephalus (iNPH) is an elderly dementia caused by abnormal metabolism in the cerebrospinal fluid (CSF). The tap test is the current basis for confirming iNPH, but it shows very low sensitivity, indicating that many patients who might be cured by a shunt operation will be missed. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, we found two transferrin isoforms: one had a unique N-glycan (Tf-1) whereas the other had N-glycan similar to that of serum transferrin (Tf-2). Glycan analyses revealed that Tf-1 had branching (biantennary) asialo- and agalacto-complex type N-glycans (N-acetylglucosamine [GlcNAc]-terminated glycans), which carried bisecting ß1,4-N-acetylglucosamine and core α1,6-fucose. To examine glycoform whether changes in iNPH, we introduced the Tf-2/Tf-1 ratio as a diagnostic index, which minimized blot-to-blot variations in measurement. The Tf-2/Tf-1 ratios of iNPH patients are significantly higher than those of controls (p = 0.0019) and Alzheimer's patients (p = 0.0010). This suggests that the Tf-2/Tf-1 ratio could distinguish iNPH from Alzheimer's disease, and possibly other dementias. In conclusion, glycoform analysis has diagnostic potential in neurological diseases.

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RESUMEN

We have established high-throughput lectin-antibody ELISAs to measure different glycans on transferrin (Tf) in cerebrospinal fluid (CSF) using lectins and an anti-transferrin antibody (TfAb). Lectin blot and precipitation analysis of CSF revealed that PVL (Psathyrella velutina lectin) bound an unique N-acetylglucosamine-terminated N-glycans on "CSF-type" Tf whereas SSA (Sambucus sieboldiana agglutinin) bound α2,6-N-acetylneuraminic acid-terminated N-glycans on "serum-type" Tf. PVL-TfAb ELISA of 0.5 µL CSF samples detected "CSF-type" Tf but not "serum-type" Tf whereas SSA-TfAb ELISA detected "serum-type" Tf but not "CSF-type" Tf, demonstrating the specificity of the lectin-TfAb ELISAs. In idiopathic normal pressure hydrocephalus (iNPH), a senile dementia associated with ventriculomegaly, amounts of the SSA-reactive Tf were significantly higher than in non-iNPH patients, indicating that Tf glycan analysis by the high-throughput lectin-TfAb ELISAs could become practical diagnostic tools for iNPH. The lectin-antibody ELISAs of CSF proteins might be useful for diagnosis of the other neurological diseases.

RESUMEN

BACKGROUND: The indirect antiglobulin test (IAT) can be potentiated by agents such as polyethylene glycol (PEG-IAT) and albumin (Alb-IAT). PEG-IAT is generally regarded as superior to Alb-IAT for the detection of clinically significant red blood cell (RBC) antibodies. However, supporting data come from Caucasian-dominant populations. Non-Caucasian populations should be investigated as well. MATERIAL AND METHODS: In this single-centre, retrospective, sequential study, Alb-IAT was used from 1989 to 1996 (8 years) and PEG-IAT from 1997 to 2008 (12 years). Pre-transfusion RBC alloantibody detection rates and specificity, post-transfusion alloantibody production, and the incidence of delayed haemolytic transfusion reaction were assessed and compared for the two periods. RESULTS: Although overall RBC alloantibody detection rates were comparable, PEG-IAT more frequently detected clinically significant antibodies such as anti-E, anti-Fy(b), and anti-Jk(a), and less frequently detected insignificant antibodies such as anti-Le(b) and anti-P(1). New alloantibodies emerged comparably during the two periods. Delayed haemolytic transfusion reaction was less frequent during the PEG-IAT period (0.30% versus 0.12%, p<0.05). CONCLUSION: PEG-IAT was superior in the detection of clinically significant antibodies, reduced the detection of insignificant antibodies, and prevented delayed haemolytic transfusion reaction better than Alb-IAT among Japanese transfusion recipients in this retrospective survey of limited power.

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