## 3 MALDI Non-Imaging MS Analysis of GSLs
### MALDI Non-Imaging MS Analysis of GSLs in Pathology
#### 3.5.1 GSLs in Storage Diseases  
Storage diseases represent a family of inherited metabolic disorders, which are defined by the abnormal accumulation of certain substances (lipids, carbohydrates, or proteins) within cells and tissues of the body, leading to various symptoms and organ dysfunction. Regarding GSLs, there are quite a few studies that look into deciphering the mechanisms of such diseases, with the purpose of either finding new and easy ways to diagnose a disease, or finding the pathway of a possible treatment. All GSL lysosomal storage diseases are multimorbidity diseases and the majority have a neurodegenerative clinical evolution, emphasizing the biological significance of GSLs in the brain. Taketomi et al. [142] focused only on GM1, and how the aging process affects the long-chain base composition of GM1. Various samples of GM1 were used, specifically brain tissue samples from patients with GM1 gangliosidosis, sudanophilic leukodystrophy, infantile type GM1 gangliosidosis, Spielmeyer-Vogt type amaurotic idiocy, schizophrenia, Gaucher disease, Schilder's disease, nuclear jaundice, and brain edema. Once again, DE MALDI MS was used, under the same conditions as mentioned before [123]. The findings are that the proportion of d18:1 decreases, d18 remains fairly constant, whereas the proportions of d20:1 and d20 increase with age. The sphingoid base composition in the GM1 adult-type gangliosidosis appeared fairly normal, similar to a normal adult human brain. Furthermore, abnormal results were determined in the samples of infantile type GM1 gangliosidosis and two samples from Spielmeyer-Vogt type amaurotic idiocy, with the latter found to be a similar long-chain base composition with the GM1 as the sample from a Gaucher disease brain tissue sample. It was theorized that the abnormal GM1 long-chain base composition in the brain tissues of early age patients may be influenced by the accumulation of GM1, whereas in the Spielmeyer-Vogt type amaurotic idiocy it may reflect an abnormal metabolism of the long-chain bases of GM1. 1. GM1 Gangliosidosis  
GM1 gangliosidosis represents a subtype of storage diseases, a class of hereditary metabolic disorders characterized by the irregular buildup of GM1 ganglioside, a specific type of GSLs. This accumulation leads to a range of symptoms and organ dysfunction as normal cellular processes are disrupted. Sugiyama et al. [123] used a DE MALDI-TOF MS (Voyager Elite XL Biospectrometry Workstation with nitrogen laser pulsed at 337 nm wavelength) for identifying several gangliosides from pathological brain tissues (GM1 in brain tissue of GM1 gangliosidosis). Using both 2.5 DHB and \(\alpha\)-CHCA as matrices for establishing a suitable protocol, the authors use a method of microwave-mediated saponification for the gangliosides, for preparing lysogangliosides, in order to determine the ceramide composition. Both ion modes, negative and positive, were employed. Comparing the spectra obtained with the calculated values of monoisotopic molecular ions, the results were promising, with GM1 found at \(m/z\) 1544.86 and 1572.88 (monoisotopic masses \(\left[\mathrm{M-H}\right]^{-}\) having (d18:1/C18:0), and (d20:1/C18:0), respectively). No loss of sialic acid was observed. Determination of GM1 ganglioside from the cerebellum and cerebrum tissues from a patient suffering from GM1 gangliosidosis was also achieved through DE-MALDI-TOF MS (Voyager Elite XL, PerSeptive Biosystems, Framingham, MA) 337 nm laser wavelength and 2,5 DHB matrix) by Fujiwaki et al. [31]. Accumulation of GM1 and asialo GM1 was found in the samples at \(m/z\) 1517--GM1 (d18:1/C16) \(\left[\mathrm{M-H}\right]^{-}\), 1545--GM1 (d18:1/C18) \(\left[\mathrm{M-H}\right]^{-}\), 1277--asialo GM1 (18:1/C18) \(\left[\mathrm{M+Na}\right]^{+}\), and 1305--asialo GM1 (d20:1/C18) \(\left[\mathrm{M+Na}\right]^{+}\)[30]. In this study, the sphingolipid fraction was prepared by homogenizing the tissue sample in chloroform/methanol (2:1). The crude lipids were obtained through ultrasonication and filtration.