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PubMed1980

GM1 ganglioside concentration in the cerebrospinal fluid of neonates and children.

GM1 ganglioside concentration was measured by radioassay technique in individual samples of lumbar cerebrospinal fluid from 20 neonatal and 17 older pediatric patients. The lumbar CSF GM1 ganglioside concentration of neonates (76.6 +/- 27.4 ng/ml) is greater than that of older infants and children (31.9 +/- 22.2 ng/ml). The lower range of GM1 ganglioside concentration of CSF from older pediatric patients is similar to the previously reported adult CSF values. The mean CSF GM1 ganglioside concentration in pediatric patients with active neurologic disease (53.1 +/- 30.0 ng/ml) is greater than that of children without central nervous system pathology. The temporal evolution and magnitude above baseline values of lumbar CSF GM1 ganglioside concentration in three neonates was correlated with the clinical status of these patients.

Adolescent↗
PubMed2001

Anencephaly: structural characterization of gangliosides in defined brain regions.

Gangliosides from histopathologically-defined human cerebrum-resembling remnant and cerebellum from 37 and 30 gestational week-old anencephaluses were identified using mass spectrometry and high performance thin layer chromatography combined with immunochemical analysis in comparison to respective normal newborn/fetal and adult brain regions. A novel strategy of nano-electrospray ionization quadrupole time-of-flight tandem MS has been developed for identification of ganglioside components in complex mixtures. By morphoanatomical and histological investigation the anencephalic cerebral remnant was found to be aberrant, while the anencephalic cerebellum was defined as normal. Total ganglioside concentrations in the anencephalic cerebral remnant and the cerebellum were 34% and 13% lower in relation to the age-matched controls. In the cerebral remnant, GD3, GM2 and GT1b were elevated, while GD1a was decreased in the anencephalic cerebral remnant, but enriched in anencephalic cerebellum. GQ1b was reduced in both anencephalic regions. Gg4Cer, GM1b and GD1alpha, members of the alpha-series biosynthetic pathway, and neolacto-series gangliosides were found to be present in anencephalic, as well as in normal, fetal and adult brain tissues, indicating the occurrence of these biosynthetic pathways in human brain. In both cerebral and cerebellar anencephalic tissues, GM1b, GD1alpha, nLM1 and nLD1 were expressed at a higher rate in relation to normal tissue. It can be demonstrated that the anencephalic cerebral remnant, as a primitive brain structure, represents a naturally-occurring model to study the ganglioside involvement in induction of aberrant brain development.

Anencephaly↗
PubMed1995

New data on content and distribution of gangliosides in human milk.

The content and distribution of gangliosides, and total lipid content, were studied in human milk samples from different periods of lactation. We found a significant correlation (r = 0.5564; p = 0.0165) between ganglioside and total lipid contents. There was a selective change in the relative concentrations of GD3 and GM3 during lactation. The most abundant ganglioside in samples from the first three weeks of lactation was GD3, whereas after the first month, GM3 was the major ganglioside. In addition to GD3 and GM3, previously known to be present in human milk, we detected several previously unreported highly polar gangliosides.

Chromatography, Thin Layer↗
PubMed1990

Cold-induced and postnatal changes in brown adipose tissue ganglioside levels.

Effects of cold and postnatal development were studied on brown adipose tissue (BAT) ganglioside levels in rats. Interscapular BAT was defatted by cold acetone before ganglioside extraction. Gangliosides were determined using HPTLC. Major ganglioside in BAT was found to be GM3. BAT GM3 level per g of fresh tissue weight as well as fat-free dry matter significantly increased in cold-acclimated rats (CA) and in rats reared in cold for 27 generations. BAT GM3 level per g of fresh weight as well as fat-free dry matter was significantly higher in 4-day- and 14-day-old rats than that in adult animals (12 weeks old). It was also shown that the higher levels of BAT GM3 were associated with greater BAT weight relative to body weight. These results suggest that BAT ganglioside, especially GM3, is implicated in growth and/or function of BAT in terms of cold-induced and postnatal changes of this tissue.

Acclimatization↗
PubMed2006

Ganglioside mimicry as a cause of Guillain-Barré syndrome.

Guillain-Barré syndrome (GBS), characterized by acute progressive limb weakness and areflexia, is the prototype of postinfectious autoimmune diseases. Campylobacter jejuni is the most frequently identified agent of infection in GBS patients, often preceding acute motor axonal neuropathy (AMAN), a variant of GBS. Anti-GM1, anti-GM1b, anti-GD1a, and anti-GalNAc-GD1a IgG antibodies are associated with AMAN. Carbohydrate mimicry [Galbeta1-3GalNAcbeta1-4(NeuAcalpha2-3)Galbeta1-] was seen between the lipo-oligosaccharide of C. jejuni isolated from an AMAN patient and human GM1 ganglioside. Sensitization with the lipo-oligosaccharide of C. jejuni induces AMAN in rabbits as does sensitization with GM1 ganglioside. Paralyzed rabbits have pathological changes in their peripheral nerves identical to changes seen in human GBS. C. jejuni infection may induce anti-ganglioside antibodies by molecular mimicry, eliciting AMAN. This is the first verification of the causative mechanism of molecular mimicry in an autoimmune disease. To express ganglioside mimics, C. jejuni requires specific gene combinations that function in sialic acid biosynthesis or transfer. The knockout mutants of these landmark genes of GBS show reduced reactivity with GBS patients' sera, and fail to induce an anti-ganglioside antibody response in mice. These genes are crucial for the induction of neuropathogenic cross-reactive antibodies. An approach for evaluating intravenous immune globulin, a treatment for GBS, based on our animal model of AMAN is also discussed in this review, and recent advances made in this field are described.

Animals↗
PubMed1996

Autoimmunity to the GM2-1 islet ganglioside before and at the onset of type I diabetes.

Recently, the GM2-1 pancreatic islet ganglioside, proposed as a potential autoantigen in type I diabetes autoimmunity, has been biochemically characterized and found to be a novel ganglioside structure. In the present study, we aimed to determine whether an autoimmune response toward this novel islet molecule is 1) present in type I diabetes and is specifically directed against this molecule and not to gangliosides in general and 2) predictive of disease in high-risk subjects. To this end, the following patients have been studied: 1) 24 newly diagnosed type I diabetic subjects, 20 islet cell autoantibody (ICA)-negative first-degree relatives of type I diabetic subjects, and 25 age-matched normal control individuals; and 2) 31 prospectively evaluated ICA+ first-degree relatives of type I diabetic subjects who were followed for up to 10 years, during which 14 of them developed type I diabetes. A direct assay for autoantibodies to GM2-1 and to other pancreatic gangliosides (GM3, GD3, GD1a) was developed using an indirect immunoperoxidase technique performed directly on thin layer chromatography plates. Anti-GM2-1 autoantibodies (all belonging to the IgG class) were expressed in a high percentage of newly diagnosed type I diabetic subjects (71%), while no significant difference was found in the expression of antibodies directed against other pancreatic gangliosides (GM3, GD3, GD1a) among the different groups studied. Anti-GM2-1 autoantibodies were also present in ICA+ relatives (64%) (P < 0.001 vs. control subjects and ICA-relatives): in this group, life table analysis of progression to diabetes showed that anti-GM2-1 autoantibodies were significantly (P < 0.001) associated with disease, occurring in all relatives developing type I diabetes within 5 years and thus identifying a cohort of ICA+ subjects with markedly increased diabetes risk.

Autoantibodies↗
PubMed1997

Increased cerebrospinal fluid ganglioside GM1 concentrations indicating neuronal involvement in all stages of HIV-1 infection.

UNLABELLED: Measurements of cerebrospinal fluid (CSF) concentrations of gangliosides can be used as markers of central nervous system (CNS) neuronal involvement. We have analysed the CSF concentrations of the four major brain gangliosides GM1, GD1a, GD1b, and GT1b at different stages of HIV-1 infection. CSF samples were collected from 44 HIV-1-infected patients and from 24 HIV-negative, healthy controls. A significantly higher mean CSF concentration of the ganglioside GM1 was found in HIV-1-infected patients than in HIV-negative controls (27 and 19 nmol/l, respectively, P<0.01). The HIV-infected patients also had a higher mean GM1 proportion of the total ganglioside concentration (11% compared with 8.5%, P < 0.01). Nine out of 27 patients with asymptomatic HIV-1 infection, three of ten with AIDS without neurological complications, and three of seven with AIDS dementia complex had CSF GM1 concentrations above the mean+2SD in the HIV-negative control group. CONCLUSION: Biochemical signs of ongoing neuronal involvement could be found in about one third of HIV-1-infected patients. The same frequency was found regardless of stage, although the highest levels of CSF gangliosides were found in patients with AIDS.

AIDS Dementia Complex↗
PubMed1992

Developmental patterns of ganglioside sialosylation coincident with neuritogenesis in cultured embryonic chick brain neurons.

Chick brain precursor neurons were observed to introduce sialic acid biosynthetically into only three specific gangliosides: monosialosyl lactosyl ceramide (GM3), disialosyl lactosyl ceramide (GD3), and disialosyl gangliotrihexosyl ceramide (GD2), when sialic acid was labeled metabolically by its obligate precursor, [3H] ManNAc. Sialosyl donor CMP-[3H]NeuAc supplied in the culture medium gave rise uniquely to surface-labeled GD3. Thus sialosyl transferase/GD3 synthase activity is expressed both intraneuronally and in the neuronal exofacial surface. Upon epidermal growth factor-induced onset of neurite outgrowth, labeled complex sialosyl gangliotetrahexosyl ceramide species of gangliosides began to appear in the embryonic neuronal plasma membrane. However, intraneuronal and exofacial sialosyl transferase/GD3 synthase activities remained constant, with or without neurite outgrowth. Moreover, simpler species of gangliosides maintained a steady quantitative sialosyl level (1.6 +/- 0.2 micrograms of sialic acid/mg of protein), whereas more complex species completely absent before neurite outgrowth accrued and reached 4.8 +/- 0.9 micrograms of sialic acid/mg of protein with full neurite development. This analysis of developmental patterns of ganglioside sialosylation has provided evidence that stable neurite outgrowth depends upon generation by the neuron of special plasma membrane with a massive content of complex higher species of gangliosides.

Animals↗
PubMed2005

Differential expression patterns of gangliosides in the ischemic cerebral cortex produced by middle cerebral artery occlusion.

Neuronal damage subsequent to transient cerebral ischemia is a multifactorial process involving several overlapping mechanisms. Gangliosides, sialic acid-conjugated glycosphingolipids, reduce the severity of acute brain damage in vitro. However their in vivo effects on the cerebral cortex damaged by ischemic infarct are unknown. To assess the possible protective role of gangliosides we examined their expression in the cerebral cortex damaged by ischemic infarct in the rat. Ischemia was induced by middle cerebral artery (MCA) occlusion, and the resulting damage was observed by staining with 2, 3, 5-triphenylterazolium chloride (TTC). High-performance thin-layer chromatography (HPTLC) showed that gangliosides GM3 and GM1 increased in the damaged cerebral cortex, and immunofluorescence microscopy also revealed a significant change in expression of GM1. In addition, in situ hybridization demonstrated an increase in the mRNA for ganglioside GM3 synthase. These results suggest that gangliosides GM1 and GM3 may be synthesized in vivo to protect the cerebral cortex from ischemic damage.

Animals↗
PubMed1989

The addition of exogenous gangliosides to cultured human cells results in the cell type-specific expression of novel surface antigens by a biosynthetic process.

After the observation that human mAb 32-27M reacts only with melanoma and astrocytoma cells cultured in the presence of fetal bovine serum, a novel pathway for the uptake of exogenous gangliosides, their further biosynthesis, and expression at the cell surface as novel Ag has been elucidated. The addition of fetal bovine serum to melanoma and astrocytoma cells growing in synthetic medium (insulin-transferrin-selenium) resulted in reactivity with Ab32-27M. As antibody 32-27M detects N-glycolylneuraminic acid (NeuGc)-containing gangliosides, the effect of adding a number of different gangliosides to melanoma and astrocytoma cells cultured in the synthetic medium was studied. Only the addition of NeuGc-GM3 resulted in the development of Ab32-27M reactivity. The identity of the antigenic structures developed after addition of fetal bovine serum or NeuGc-GM3 was determined by analysis of the gangliosides from both samples. The major component detected in melanoma cell lines was shown to be N-acetylneuraminic acid-NeuGc-GD3. Another, slower moving component, present in some melanomas and in astrocytomas may be N-acetylneuraminic acid-NeuGc-GD2. The cell type specificity for these processes can be most readily explained by postulating that all cells can take up exogenous gangliosides but only melanoma and astrocytoma cells have sufficiently high levels of GM3 alpha 2----8-sialyltransferase for the conversion of added NeuGc-GM3 to disialogangliosides to be effective. These results demonstrate a novel pathway for exogenous glycolipid processing that can lead to novel Ag expression but may also play a role in normal glycolipid metabolism and function.

Animals↗
PubMed1989

A new ganglioside of the lactotetraose series, GalNAc-3'-isoLM1, detected in human meconium.

A monoclonal antibody produced by immunization with cells of the human glioma cell line D-54 MG reacted with ganglioside GM2. The binding epitope of the antibody was found to be GalNAc beta 1-4(NeuAc alpha 2-3)Gal. Immunological detection of glycolipid antigens on thin-layer plates with this monoclonal antibody, DMAb-1, revealed the presence of a new ganglioside. This ganglioside, co-migrating with NeuAc alpha 2-6Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc beta 1-1Cer(6'-LM1) and GalNAc beta 1-4(NeuAc alpha 2-3)Gal beta 1-3GalNAc beta 1-4Gla beta 1-4Glc beta 1-1Cer (GalNAc-isoGM1) at chromatographic separation was isolated from human meconium. Its structure was determined by permethylation and fast atom bombardment-mass spectometry analyses. The new ganglioside was found to be a combination of the lacto and ganglio series gangliosides, and the structure found to be GalNAc beta 1-4(NeuAc alpha 2-3)Gal beta 1-3GlcNAc alpha 1-3Gal beta 1-4Glc beta 1-1Cer(GalNAc-3'-isoLM1).

Antibodies, Monoclonal↗
PubMed1987

Occurrence of tumor-associated ganglioside antigens with Hanganutziu-Deicher antigenic activity on human melanomas.

The specificity of antibody to NeuGc alpha 2-3Gal beta 1-4Glc-cer (GM3(NeuGc] was carefully reexamined by the method of enzyme-immunostaining on a thin layer plate. The affinity-purified antibody was found to react with NeuGc alpha 2-8NeuGc alpha 2-3Gal beta 1-4Glc-cer (GD3(NeuGc-NeuGc] and NeuGc alpha 2-8NeuAc alpha 2-3Gal beta 1-4Glc-cer (GD3(NeuGc-NeuAc], but not with NeuAc alpha 2-8NeuGc alpha 2-3Gal beta 1-4Glc-cer (GD3(NeuAc-NeuGc)) or NeuAc alpha 2-8NeuAc alpha 2-3Gal beta 1-4Glc-cer (GD3(NeuAc-NeuAc]. From this result together with the previous results, it (GD3(NeuAc-NeuAc], From this result together with the previous results, it could be concluded that the antibody recognizes the outer portion of molecular species of sialic acids in the gangliosides. By using this antibody, the expression of Hanganutziu-Deicher (HD) gangliosides could be demonstrated in human malignant melanoma. The molecular species were different among individuals examined. Among HD-antigenic gangliosides, GM3(NeuGc) was commonly found in melanoma tissues. One of the patients examined expressed GD3(NeuGc-NeuGc) and GD 3(NeuGc-NeuAc), which may be characteristic gangliosides in human melanomas, since these gangliosides could not be detected in human colon cancer or human fetal tissues.

Antigens, Heterophile↗
PubMed1985

Characterization of N-glycolylneuraminic acid-containing gangliosides as tumor-associated Hanganutziu-Deicher antigen in human colon cancer.

Hanganutziu-Deicher (HD) antigen-active N-glycolylneuraminic acid (NeuGc)-containing gangliosides were isolated and characterized from human colon cancer tissues. The antigenic gangliosides were detected by thin-layer chromatography by our newly developed method (H. Higashi, Y. Fukui, S. Ueda, S. Kato, Y. Hirabayashi, M. Matsumoto, and M. Naiki. J. Biochem., 95: 1517-1520, 1984) of enzyme immunostaining using affinity-purified chicken antibody against hematoside containing NeuGc (II3NeuGc-LacCer) and horseradish peroxidase-conjugated rabbit anti-chicken lgG. One to six species of the antigenic gangliosides were isolated from seven of 16 cases of colon cancer, whereas no antigenic compound was detected in all apparently normal colorectal tissues from 17 individuals without colorectal cancer. Tissues from different patients showed different patterns of molecular species of the antigenic gangliosides. Densitometric determination indicated that HD antigenic sialic acid, NeuGc, accounted for about 1% or less of the total lipid-bound sialic acids. Four species of antigenic gangliosides were identified as hematoside and hematoside-containing O-acyl ester (II3NeuGc-LacCer and II3 4- or 7-O-acyl-NeuGc-LacCer), GM2-containing NeuGc (II3NeuGc-GgOse3Cer), and sialylparagloboside (IV3NeuGc-nLcOse4Cer) by their behaviors on 2-dimensional thin-layer chromatography, and the effects of mild alkaline treatment, sialidase treatment, periodate oxidation, and endo-beta-galactosidase treatment.

Antigens, Heterophile↗
PubMed1985

Preparation of GM1 ganglioside molecular species having homogeneous fatty acid and long chain base moieties.

A new procedure is described for preparing the molecular species of GM1 ganglioside that carry a single fatty acid (myristic (C14:0), stearic (C18:0), arachidic (C20:0) or lignoceric (C24:0) acid) and a single long chain base (C18 or C20 sphingosine, C18 or C20 sphinganine, each of them in natural 3D(+)erythro or unnatural 3L(-)threo form). The procedure consisted of the following steps: a) alkaline hydrolysis of GM1 ganglioside in the presence of tetramethylammonium hydroxide, which produces de-N-acylation of the ceramide and de-N-acetylation of the sialic acid residue; b) specific re-N-acylation at the long chain base amino group with a new fatty acid (myristic, stearic, arachidic, or lignoceric) in the presence of 1-(3-dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride; and c) final re-N-acetylation at the level of the sialic acid residue. GM1 ganglioside molecular species, completely homogeneous in the ceramide portion, were prepared by reversed phase high performance liquid chromatography. The GM1 ganglioside molecular species were analyzed for saccharide, fatty acid, and long chain base composition by chemical and spectrometric analyses. Using a combination of the two procedures, 32 different molecular species of GM1 ganglioside, over 99% homogeneous, have been prepared.

Chemical Phenomena↗
PubMed1979

Action of Arthrobacter ureafaciens sialidase on sialoglycolipid substrates. Mode of action and highly specific recognition of the oligosaccharide moiety of ganglioside GM1.

A new bacterial sialidase (N-acetylneuraminate glycohydrolase, EC 3.2.1.18) isolated from the culture filtrate of Arthrobacter ureafaciens was characterized in detail with respect to its action on sialoglycolipids. Strong electrolytes had a reversible inhibitory effect on the action of the enzyme on brain gangliosides in accordance with Debye-Hückel effect of ionic environment on ionic activity, and resulted in an acidic shift and a broadening of the pH optimum. Both ionic and non-ionic detergents markedly enhanced the enzymic activity on the gangliosides, and caused an acidic shift on the pH optimum of this enzyme. Sulfhydryl groups seemed to be involved in its active site. This enzyme had a highly specific action on sialidase-resistant ganglioside GM1, showing about 100-fold higher activity on GM1 than Clostridium perfringens sialidase, the only sialidase so far reported to cleave the lipid substrate in the presence of bile salts. In the absence of detergents, the activity of A. ureafaciens sialidase on GM1 was very low. Ganglioside GM1 in either the monomeric or micelar form was hydrolyzed to asialo-GM1 by A. ureafaciens sialidase most efficiently in the presence of sodium cholate of about three times the GM1 molar concentration. The presence of detergents increased both the Km and Vmax values for ganglioside GM1. The oligosaccharide prepared from GM1 by ozonolysis was cleaved well by this sialidase in the absence of detergents, and no detergent was found to affect the hydrolysis. The Km value for the sugar substrate was about two orders of magnitude greater than that for the corresponding lipid substrate. It is suggested that the hydrophobic ceramide moiety increases affinity of the lipid substrate to the enzyme, but inhibits hydrolysis of the substrate, possibly due to its hydrophobic interaction with hydrophobic portions of the enzyme molecule (resulting in lower Km and Vmax for lipid substrates). This inhibition may be released by detergent due to formation of mixed micelles of sialoglycolipid and detergent molecules. It is also indicated that recognition of the specific saccharide structure of GM1 by individual sialidases is essential for release of the resistant sialyl residue, and that A. ureafaciens sialidase seemed to have an isoenzymic or oligomeric structure.

Arthrobacter↗
PubMed1984

Isolation and characterization of a novel phytosphingosine-containing GM2 ganglioside from mullet roe (Mugil cephalus).

The major ganglioside from the roe of striped mullet (Mugil cephalus) has been isolated and purified. Compositional analysis of this ganglioside revealed that it contained an equimolar ratio of the following residues: N-acetylneuraminic acid, N-acetylgalactosamine, galactose, glucose, and the long-chain base. Further structural studies by sequential enzymatic hydrolysis, permethylation analysis, and proton NMR spectroscopy indicated that the structure of the oligosaccharide moiety was identical to that of GM2 ganglioside from human brain: GalNAc beta 1----4Gal beta 1----4(3----2 alpha NeuAc)-Glc----ceramide. This ganglioside, however, differed from brain GM2 in its ceramide portion. The most striking differences are the presence of large amounts of C18 and C20 phytosphingosine (over 80% of the total long-chain bases) and the preponderance of monounsaturated alpha-hydroxy fatty acids (over 80%). Such a phytosphingosine-containing GM2 ganglioside has never been reported.

Animals↗
PubMed1999

Ferret pyramidal cell dendritogenesis: changes in morphology and ganglioside expression during cortical development.

Pyramidal cell ontogenesis and basilar dendritic differentiation were evaluated concomitantly with ganglioside expression and distribution in ferret cerebral cortex. Layer V neurons began basilar dendritogenesis on postnatal day 1 (P1) with a peak in dendritic arborization occurring at P21. Layer II/III neurons, in contrast, were in early stages of basilar dendritic differentiation at P14, resulting in a complex dendritic arbor at P28. High performance thin-layer chromatography showed numerous changes in ganglioside expression during cortical development, including a decline of GM2 in the mature cortex. The temporal expression and cellular distribution of GM2, GD2, GM1, GD3, and GM3 gangliosides in developing cerebral cortex were determined by immunocytochemistry. GM2 immunoreactivity (IR) was most prominent in layer V neurons between P1 and P21 and in layer II/III neurons between P14 and P28 with staining diminishing to near absent levels in the adult. GM2-IR appeared as punctate structures within the somatodendritic domain and by electron microscopy was shown to be membrane-bound vesicles often in close proximity to the plasmalemma. Expression of GM2, but not of other gangliosides studied, followed two well-documented developmental neurogenic gradients: ventrolateral to dorsomedial and radial (inside-first outside-last). Onset of significant GD2 expression in layer II/III and V pyramidal cells was delayed until P14 and persisted in adult neocortex. GD3 was localized most prominently to glial-like cells, whereas GM1 was primarily localized to white matter. The close temporal and spatial concordance of GM2-IR in cortical pyramidal neurons undergoing dendritogenesis is consistent with its proposed role as a modulator of dendritic differentiation.

Aging↗
PubMed1982

Assignment of the carbon-13 nuclear magnetic resonance spectra of gangliosides GM4, GM3, GM2, GM1, GD1a, GD1b, and GT1b.

Complete 13C nuclear magnetic resonance assignments are presented for gangliosides in the series GM4, GM3, GM2, GM1, GD1a, GD1b, and GT1b. The gangliosides studied are related by the sequential addition of single saccharide residues. The structural relationships among these molecules were confirmed and subsequently utilized to provide the basis for a detailed investigation of 13C NMR oligomer-monomer shielding differences accompanying increasing oligosaccharide complexity. This gradual increase in complexity was reflected in the 13C NMR spectra and proved to be of significant value in the assignment task, resulting in the reassignment of four GM1 resonances from our previous work [Sillerud, L. O., Prestegard, J. H., Yu, R. K., Schafer, D. E., & Konigsberg, W. H. (1978) Biochemistry 17, 2619--2628]. The carboxyl-containing sialic acids in gangliosides have glycosidic linkage resonance shifts only approximately 30% as large as those found for neutral hexopyranosides; thus, care must be used in interpreting the 13C spectra of charge oligosaccharides. Secondary structural effects are also found to produce shifts in the resonances of the sialic acid adjacent to the GalNAc residue of GM2 and the more complex gangliosides, leading to inequivalence of the sialic acids in GD1a, GD1b, and GT1b.

Animals↗