A new liquid chromatography/tandem mass spectrometry method for quantification of gangliosides in human plasma.

Gangliosides are a family of glycosphingolipids characterized by mono- or polysialic acid-containing oligosaccharides linked through 1,3- and 1,4-ß glycosidic bonds with subtle differences in structure that are abundantly present in the central nervous systems of many living organisms. Their cellular surface expression and physiological malfunction are believed to be pathologically implicated in considerable neurological disorders, including Alzheimer and Parkinson diseases. Recently, studies have tentatively elucidated that mental retardation or physical stagnation deteriorates as the physiological profile of gangliosides becomes progressively and distinctively abnormal during the development of these typical neurodegenerative syndromes. In this work, a reverse-phase liquid chromatography/tandem mass spectrometry (LC/MS/MS) assay using standard addition calibration for determination of GM2, GM3, GD2, and GD3 in human plasma has been developed and validated. The analytes and internal standard were extracted from human plasma using a simple protein precipitation procedure. Then the samples were analyzed by reverse-phase ultra-performance liquid chromatography (UPLC)/MS/MS interfaced to mass spectrometry with electrospray ionization using a multiple reaction monitoring mode to obtain superior sensitivity and specificity. This assay was validated for extraction recovery, calibration linearity, precision, and accuracy. Our quick and sensitive method can be applied to monitor ganglioside levels in plasma from normal people and neurodegenerative patients.

[Clinical features of GM1 and GM2 gangliosidosis in own observation]. / Obraz kliniczny gangliozydoz GM1 i GM2 w materiale wlasnym.

BACKGROUND: Lysosomal enzyme defects leeds to intracellular storage and cause damage in many organs, almost always affects central nervous system. AIM. The aim of the study was to reveal the location and clinical characteristics of gangliosidosis in pediatric neurology. MATERIAL AND METHODS: Gangliosidoses GM1 and GM2 (Sandhoff type) was diagnosed in 4 children, aged 1-13 years (mean 4,5 years), 2 girls and 2 boys. GM2 was diagnosed in 3 patients (early childhood in 2, juvenile in 1) and GM1 infantile form in 1, which was 0.024% of hospitalized children in 2007-2008. The diagnosis was made on the basis of blood leukocyte enzyme analyse. RESULTS: Clinical course of both type infantile gangliosidosis revealed to be similar. Psychomotor deterioration and symptomatic epilepsy were predominant symptoms as well as typical changes of eye fundus like cherry red spot. Juvenile type was less symptomatic, with tremor, dysarthria and ataxia. Neuroimage changes varied and were normal in some, with changes in corpus callosum and with distant changes in white matter and subcortical nuclei in others. CONCLUSIONS: Gangliosidosis should be suspected in adolescent with tremor, ataxia and dysarthria.

Laboratory diagnosis of canine GM2-gangliosidosis using blood and cerebrospinal fluid.

In the present study, laboratory techniques were used to diagnose canine GM2-gangliosidosis using blood and cerebrospinal fluid (CSF) that can be collected noninvasively from living individuals. Lysosomal acid beta-hexosaminidase (Hex) was measured spectrofluorometrically using 4-methylumbelliferyl N-acetyl-beta-D-glucosaminide and 4-methylumbelliferyl 7-(6-sulfo-2-acetamido-2-deoxy-beta-D-glucopyranoside) as substrates. Main isoenzymes A and B of Hex in leukocytes were also analyzed using cellulose acetate membrane electrophoresis. GM2-ganglioside in CSF was detected and determined quantitatively by using thin-layer chromatography/enzyme-immunostaining method with anti-GM2-ganglioside antibody. In normal dogs, Hex activities could be determined in leukocytes, serum, and CSF and the total activities were markedly reduced in all the enzyme sources in a dog with Sandhoff disease. Electrophoresis of a leukocyte lysate from a normal dog showed that the Hex A and Hex B were not separated distinctively with formation of a broad band, whereas there were no bands in electrophoresis of a lysate from a dog with Sandhoff disease, showing a deficiency in the total enzyme activity. GM2-ganglioside could be detected and determined quantitatively in as little as 100 microl of canine CSE GM2-ganglioside in CSF in a dog with Sandhoff disease increased to 46 times the normal level. In conclusion, the methods in the present study are useful for diagnosis of canine GM2-gangliosidosis. These techniques enable definitive and early diagnosis of canine GM2-gangliosidosis even if tissues and organs cannot be obtained.

Thermodynamic determination of plasma and leukocyte beta-hexosaminidase isoenzymes in homozygote and heterozygote carriers for the GM2 gangliosidosis B1 variant.

In the GM2 gangliosidosis B1 variant, the mutated isoenzyme A of beta-hexosaminidase (Hex) is incapable of hydrolyzing ganglioside GM2 and negatively charged substrates. Biochemical characterization of this lysosomal disease is carried out using synthetic alpha-subunit-specific sulfated substrates, as heat-inactivation assays are not applicable. The apparent enzyme activation energy of Hex using the chromogenic substrate 3,3'-dichlorophenolsulfonphthaleinyl N-acetyl-beta-D-glucosaminide is related directly to the relative proportions of Hex A and Hex B isoenzymes. This thermodynamic variable was used for the study of Hex enzyme heterogeneity in 3 patients with the GM2 gangliosidosis B1 variant and 6 heterozygote carriers. Hex activity was determined at 25 degrees C, 30 degrees C, 35 degrees C, and 37 degrees C in a Cobas Bio analyzer (Roche Diagnostics, Basel, Switzerland), and Arrhenius plot slopes and apparent activation energies were calculated in plasma samples and mononuclear and polymorphonuclear leukocyte lysates. The determination of the Hex isoenzymes in plasma presented a high discrimination power for B1 variant patients but not for heterozygote carriers, in whom false-negative results may be obtained. However, thermodynamic evaluation of the isoenzyme composition of Hex in leukocyte lysates permits the biochemical identification of patients with the GM2 gangliosidosis B1 variant and of heterozygote carriers.