ABSTRACT
Hemoglobin A1c (HbA1c) is now considered to be the marker of choice in diagnosis and management of diabetes mellitus, based on the results of certain landmark clinical trials. Herein, we report the case of a 52-year-old ethnic Southeast Asian Indian man with impaired glucose tolerance whose glycated hemoglobin (ie, HbA1c) levels, as measured via Bio-Rad D10 high-performance liquid chromatography (HPLC) and Roche Tina-quant immunoassay were 47.8% and 44.0%, respectively. No variant hemoglobin (Hb) peak was observed via the D10 chromatogram. We assayed the patient specimen on the Sebia MINICAP capillary electrophoresis platform; the HbA1c level was 6.8%, with a large variant Hb peak of 42.0%. This finding suggested the possible presence of the heterozygous Hb Hope, which can result in spuriously elevated HbA1c results on HPLC and turbidimetric immunoassays. Although the capillary electrophoresis system was able to identify the variant, the A1c results should not be considered accurate due to overlapping of the variant and adult Hb peaks on the electrophoretogram reading. Hb Hope is usually clinically silent but can present such analytical challenges. Through this case study, we critically discuss the limitations of various HbA1c assay methods, highlighting the fact that laboratory professionals need to be aware of occurrences of Hb Hope, to help ensure patient safety.
Subject(s)
Diabetes Mellitus/diagnosis , Glycated Hemoglobin/metabolism , Hemoglobins, Abnormal/metabolism , Chromatography, High Pressure Liquid , Diabetes Mellitus/blood , Electrophoresis, Capillary , Hematologic Tests , Humans , Immunoassay , Male , Middle AgedABSTRACT
The study has demonstrated that dopamine induces membrane depolarization and a loss of phosphorylation capacity in dose-dependent manner in isolated rat brain mitochondria during extended in vitro incubation and the phenomena are not prevented by oxyradical scavengers or metal chelators. Dopamine effects on brain mitochondria are, however, markedly prevented by reduced glutathione and N-acetyl cysteine and promoted by tyrosinase present in the incubation medium. The results imply that quinone oxidation products of dopamine are involved in mitochondrial damage under this condition. When PC12 cells are exposed to dopamine in varying concentrations (100-400µM) for up to 24h, a pronounced impairment of mitochondrial bio-energetic functions at several levels is observed along with a significant (nearly 40%) loss of cell viability with features of apoptotic nuclear changes and increased activities of caspase 3 and caspase 9 and all these effects of dopamine are remarkably prevented by N-acetyl cysteine. N-acetyl cysteine also blocks nearly completely the dopamine induced increase in reactive oxygen species production and the formation of quinoprotein adducts in mitochondrial fraction within PC12 cells and also the accumulation of quinone products in the culture medium. Clorgyline, an inhibitor of MAO-A, markedly decreases the formation of reactive oxygen species in PC12 cells upon dopamine exposure but has only mild protective actions against quinoprotein adduct formation, mitochondrial dysfunctions, cell death and caspase activation induced by dopamine. The results have indicated that quinone oxidation products and not reactive oxygen species are primarily involved in cytotoxic effects of dopamine and the mitochondrial impairment plays a central role in the latter process. The data have clear implications in the pathogenesis of Parkinson's disease.
Subject(s)
Dopamine/toxicity , Mitochondria/drug effects , Parkinson Disease/etiology , Quinones/toxicity , Animals , Apoptosis/drug effects , Brain/drug effects , Caspases/metabolism , Dopamine/metabolism , Energy Metabolism/drug effects , Membrane Potential, Mitochondrial/drug effects , Mitochondria/physiology , Oxidation-Reduction , Oxidative Phosphorylation/drug effects , PC12 Cells , Parkinson Disease/metabolism , Rats , Reactive Oxygen Species/metabolismABSTRACT
This study demonstrates that in vitro incubation of isolated rat brain mitochondria with recombinant human alpha-synuclein leads to dose-dependent loss of mitochondrial transmembrane potential and phosphorylation capacity. However, alpha-synuclein does not seem to have any significant effect on the activities of respiratory chain complexes under similar conditions of incubation suggesting that the former may impair mitochondrial bioenergetics by direct effect on mitochondrial membranes. Moreover, the recombinant wild type alpha-synuclein and different mutant forms (A30P, A53T and E46K) have essentially similar effects on rat brain isolated mitochondria. The results are significant in view of the fact that alpha-synucleinopathy is involved in the pathogenesis of Parkinson's disease.
