Articoli di riviste: "MALDI"

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Osa, Morichika, Maria Cecilia Belo, Zita Dela Merced, Annavi Marie G. Villanueva, Jaira Mauhay, Alyannah Celis, Melissa Catli et al. "Performance of MALDI–TOF Mass Spectrometry in the Philippines". Tropical Medicine and Infectious Disease 6, n. 3 (26 giugno 2021): 112. http://dx.doi.org/10.3390/tropicalmed6030112.

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Identification of the causative pathogen in infectious diseases is important for surveillance and to guide treatment. In low- and middle-income countries (LMIC), conventional culture and identification methods, including biochemical methods, are reference-standard. Biochemical methods can lack sensitivity and specificity and have slow turnaround times, causing delays in definitive therapy. Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI–TOF MS) is a rapid and accurate diagnostic method. Most studies comparing MALDI–TOF MS and biochemical methods are from high-income countries, with few reports from LMIC with tropical climates. The aim of this study was to assess the performance of MALDI–TOF MS compared to conventional methods in the Philippines. Clinical bacterial or fungal isolates were identified by both MALDI–TOF MS and automated (VITEK2) or manual biochemical methods in the San Lazaro Hospital, Metro Manila, the Philippines. The concordance between MALDI–TOF MS and automated (VITEK2) or manual biochemical methods was analyzed at the species and genus levels. In total, 3530 bacterial or fungal isolates were analyzed. The concordance rate between MALDI–TOF MS and biochemical methods was 96.2% at the species level and 99.9% at the genus level. Twenty-three isolates could not be identified by MALDI–TOF MS. In this setting, MALDI–TOF MS was accurate compared with biochemical methods, at both the genus and the species level. Additionally, MALDI–TOF MS improved the turnaround time for results. These advantages could lead to improved infection management and infection control in low- and middle-income countries, even though the initial cost is high.

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KAWABATA, Shin-ichirou. "MALDI-TOFMS". Journal of the Japan Society of Colour Material 79, n. 6 (2006): 257–62. http://dx.doi.org/10.4011/shikizai1937.79.257.

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Kajiwara, Hideyuki. "MALDI biotyping". Nippon Shokuhin Kagaku Kogaku Kaishi 65, n. 11 (15 novembre 2018): 541. http://dx.doi.org/10.3136/nskkk.65.541.

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Wisztorski, Maxence, Rémi Lemaire, Jonathan Stauber, Sonia Ait Menguellet, Olivia Jardin-Mathé, Robert Day, Michel Salzet e Isabelle Fournier. "Imagerie MALDI". médecine/sciences 23 (marzo 2007): 31–38. http://dx.doi.org/10.1051/medsci/2007231s31.

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Chakrabarti, A. "MALDI-TOF". International Journal of Infectious Diseases 45 (aprile 2016): 26. http://dx.doi.org/10.1016/j.ijid.2016.02.090.

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Chin, Jefferson, Elizabeth Wood, Grace S. Peters e Dieter M. Drexler. "Acoustic Sample Deposition MALDI-MS (ASD-MALDI-MS)". Journal of Laboratory Automation 21, n. 1 (febbraio 2016): 204–7. http://dx.doi.org/10.1177/2211068215594769.

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Rim, John Hoon, Yangsoon Lee, Sung Kuk Hong, Yongjung Park, MyungSook Kim, Roshan D’Souza, Eun Suk Park, Dongeun Yong e Kyungwon Lee. "Insufficient Discriminatory Power of Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry Dendrograms to Determine the Clonality of Multi-Drug-ResistantAcinetobacter baumanniiIsolates from an Intensive Care Unit". BioMed Research International 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/535027.

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While pulsed-field gel electrophoresis (PFGE) is recognized as the gold standard method for clonality analysis, MALDI-TOF MS has recently been spotlighted as an alternative tool for species identification. Herein, we compared the dendrograms of multi-drug-resistant (MDR)Acinetobacter baumanniiisolates by using MALDI-TOF MS with those by using PFGE. We used direct colony and protein extraction methods for MALDI-TOF MS dendrograms. The isolates with identical PFGE patterns were grouped into different branches in MALDI-TOF MS dendrograms. Among the isolates that were classified as very close isolates in MALDI-TOF MS dendrogram, PFGE band patterns visually showed complete differences. We numeralized similarity among isolates by measuring distance levels. The Spearman rank correlation coefficient values were 0.449 and 0.297 between MALDI-TOF MS dendrogram using direct colony and protein extraction method versus PFGE, respectively. This study is the first paper focusing solely on the dendrogram function of MALDI-TOF MS compared with PFGE. Although MALDI-TOF MS is a promising tool to identify species in a rapid manner, our results showed that MALDI-TOF MS dendrograms could not substitute PFGE for MDRAcinetobacter baumanniiclonality analysis.

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NIRASAWA, TAKASHI. "MALDI-TOF-MS." Kagaku To Seibutsu 34, n. 4 (1996): 255–59. http://dx.doi.org/10.1271/kagakutoseibutsu1962.34.255.

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Kriegsmann, J., R. Casadonte, F. Zweynert, M. Kriegsmann, M. Otto e S. Deininger. "MALDI-TOF-Bildgebung". Zeitschrift für Rheumatologie 72, n. 7 (16 agosto 2013): 724–28. http://dx.doi.org/10.1007/s00393-013-1239-1.

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Chen, Xin-Fei, Xin Hou, Meng Xiao, Li Zhang, Jing-Wei Cheng, Meng-Lan Zhou, Jing-Jing Huang, Jing-Jia Zhang, Ying-Chun Xu e Po-Ren Hsueh. "Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) Analysis for the Identification of Pathogenic Microorganisms: A Review". Microorganisms 9, n. 7 (19 luglio 2021): 1536. http://dx.doi.org/10.3390/microorganisms9071536.

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Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been used in the field of clinical microbiology since 2010. Compared with the traditional technique of biochemical identification, MALDI-TOF MS has many advantages, including convenience, speed, accuracy, and low cost. The accuracy and speed of identification using MALDI-TOF MS have been increasing with the development of sample preparation, database enrichment, and algorithm optimization. MALDI-TOF MS has shown promising results in identifying cultured colonies and rapidly detecting samples. MALDI-TOF MS has critical research applications for the rapid detection of highly virulent and drug-resistant pathogens. Here we present a scientific review that evaluates the performance of MALDI-TOF MS in identifying clinical pathogenic microorganisms. MALDI-TOF MS is a promising tool in identifying clinical microorganisms, although some aspects still require improvement.

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Qiao, Hui, Gamini Piyadasa, Victor Spicer e Werner Ens. "Analyte distributions in MALDI samples using MALDI imaging mass spectrometry". International Journal of Mass Spectrometry 281, n. 1-2 (marzo 2009): 41–51. http://dx.doi.org/10.1016/j.ijms.2008.11.015.

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Oluwatosin Ogundairo, Oluwatoyin Ayo-Farai, Chinedu Paschal Maduka, Chiamaka Chinaemelum Okongwu, Abdulraheem Olaide Babarinde e Olamide Tolulope Sodamade. "REVIEW ON MALDI MASS SPECTROMETRY AND ITS APPLICATION IN CLINICAL RESEARCH". International Medical Science Research Journal 3, n. 3 (12 dicembre 2023): 108–26. http://dx.doi.org/10.51594/imsrj.v3i3.642.

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Mass spectrometry has emerged as a powerful analytical tool in various scientific disciplines, and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS) has gained significant prominence, particularly in the field of clinical research. This review provides a comprehensive overview of MALDI-MS, its principles, and its applications in clinical research settings. This study delves into the technical aspects of MALDI-MS, discussing key components such as the matrix, sample preparation methods, and mass analyzers. It highlights recent advancements and innovations in MALDI-MS technology, showcasing its evolution and adaptation to meet the increasing demands of clinical applications. MALDI-MS involves the use of laser energy to desorb and ionize molecules from a solid-phase matrix, enabling the analysis of a wide range of biomolecules, including proteins, peptides, lipids, and metabolites. The technique's ability to analyze complex biological samples with high sensitivity and specificity has made it invaluable in clinical research. In the realm of clinical research, MALDI-MS has found applications in disease diagnosis, biomarker discovery, and therapeutic monitoring. The review explores specific examples of MALDI-MS applications in various clinical areas, including oncology, infectious diseases, and metabolic disorders. Case studies and experimental findings are presented to underscore the practical utility of MALDI-MS in these contexts. Moreover, the review discusses the challenges and limitations associated with MALDI-MS in clinical research, such as standardization of protocols, reproducibility, and sample heterogeneity. Strategies to overcome these challenges are addressed, emphasizing ongoing efforts to enhance the reliability and robustness of MALDI-MS-based analyses in clinical settings. MALDI-MS has proven to be a transformative technology in clinical research, offering unique insights into the molecular landscape of diseases and paving the way for personalized medicine. As MALDI-MS continues to evolve, its integration into routine clinical workflows holds the potential to revolutionize diagnostics and improve patient outcomes. This review serves as a valuable resource for researchers, clinicians, and industry professionals seeking a comprehensive understanding of MALDI-MS and its myriad applications in the field of clinical research. Keywords: MALDI-MS, Clinical Research, Review, Ionization Mass Spectrometry.

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Madhavan, Anitha, Arun Sachu, Nandini Sethuraman, Anil Kumar e Jayalakshmi Vasudevapanicker. "Evaluation of Matrix-assisted laser desorption/ionization Time-of flight Mass spectrometry (MALDI TOF MS) and VITEK 2 in routine microbial identification". Ghana Medical Journal 55, n. 4 (1 dicembre 2021): 308–10. http://dx.doi.org/10.4314/gmj.v55i4.12.

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Background: Microbial Identification was done by phenotypic methods. VITEK-2 and Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) are now being increasingly used in laboratories.Objectives: To compare and evaluate the usefulness of MALDI-TOF MS and VITEK-2 in routine microbial identification.Methods: The performances of MALDI-TOF MS and VITEK 2 were compared for identifying microorganisms.Results: MALDI- TOF MS and VITEK-2 correctly identified 96 % (96/100) and 97% (97/100) of the isolates upto the genus level.Conclusion: MALDI TOF MS and VITEK -2 gave comparable identification and error rates. The rapid reduction in turnaround time with MALDI TOF is a significant game-changer in the field of clinical microbiology

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Ulshina, D. V., D. A. Kovalev, D. G. Ponomarenko, D. V. Rusanova, N. M. Shvetsova, T. V. Taran, I. V. Kuznetsova et al. "APPLICATION OF TIME-OF-FLIGHT MASS-SPECTROMETRY FOR DETECTION OF CAUSATIVE AGENT OF BRUCELLOSIS IN BLOOD SAMPLES IN EXPERIMENT". Journal of microbiology epidemiology immunobiology, n. 4 (28 agosto 2017): 9–17. http://dx.doi.org/10.36233/0372-9311-2017-4-9-17.

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Aim.Study the possibility to apply time-of-flight mass-spectrometry for detection of causative agent of brucellosis in blood. Materials and methods. Brucella strains: 5 Brucella melitensis and 21 Brucella abortus. Protein profiling in linear mode on MALD1-TOF mass-spectrometer Microflex «Bruker Daltonics». Results. Technique for disinfection and preparation of blood samples was modified and optimized for MALDI-TOF MS analysis. 120 representative protein profiles of sera extract were obtained that contain brucellosis causative agent. A resulting peak-list (super-spectrum) of the studied protein fraction of blood extract of a conditionally healthy human within the studied group was formed and analyzed. Conclusion. A scheme of brucella detection in blood samples by MALDI-TOF MS is proposed, based on detection of a complex of 15 genus-specific fragments. Signals on mass-spectra of extracts of leukocyte fraction of blood, artificially contaminated with brucellosis causative agents are characterized.

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Rodríguez-Sánchez, Belén, María Jesús Ruiz-Serrano, Mercedes Marín, Paula López Roa, Marta Rodríguez-Créixems e Emilio Bouza. "Evaluation of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Identification of Nontuberculous Mycobacteria from Clinical Isolates". Journal of Clinical Microbiology 53, n. 8 (10 giugno 2015): 2737–40. http://dx.doi.org/10.1128/jcm.01380-15.

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Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) for the identification of nontuberculous mycobacterial (NTM) isolates was evaluated in this study. Overall, 125 NTM isolates were analyzed by MALDI-TOF and GenoType CM/AS. Identification by 16S rRNA/hsp65sequencing was considered the gold standard. Agreements between MALDI-TOF and GenoType CM/AS with the reference method were, respectively, 94.4% and 84.0%. In 17 cases (13.6%), results provided by GenoType and MALDI-TOF were discordant; however, the reference method agreed with MALDI-TOF in 16/17 cases (94.1%;P= 0.002).

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Tan, Zhi Lei, Yu Qiao Wei, Shuang Liang, Ran Zhang, Miao Liu e Shi Ru Jia. "Rapid Identification of Microorganisms Isolated from Pickled Vegetables by MALDI-TOF Mass Spectrometry". Advanced Materials Research 712-715 (giugno 2013): 494–97. http://dx.doi.org/10.4028/www.scientific.net/amr.712-715.494.

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Matrix-assisted laser desorption/ionization time-off light mass spectrometry (MALDI-TOF MS) is increasingly used as a microbial diagnostic method for species identification of pathogens. However, MALDI-TOF MS identification of food bacteria was seldom reported. Ten strains isolated from different pickled vegetables were rapid identified by MALDI-TOF MS. The results of MALDI-TOF MS were confirmed by 16S rDNA sequencing method. Different score values in MALDI-TOF MS revealed nineLeuconostoc mesenteroides and oneStaphylococcus.Identification success at the species and genus levels was 90% (9/10) and 100% (10/10), respectively.16S rDNA sequencing results showed that nine stains were identified asLeuconostoc mesenteroides and one wasStaphylococcus saprophyticus.Results obtained demonstrate that MALDI-TOFMS is a promising method for discriminating and identifying food bacteria.

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Lupșe, Irina, Mirela Flonta, Andreea Ciurea, Iulia Cristina Micu, Alexandra Roman, Emoke Pall, Dora Maria Popescu e Andrada Soancă. "Matrix-assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry (MALDI-TOF MS) for subgingival bacteriome identification in a group of treated periodontitis patients: a case series". Revista Romana de Medicina de Laborator 30, n. 2 (1 aprile 2022): 227–34. http://dx.doi.org/10.2478/rrlm-2022-0012.

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Abstract Periodontitis is a chronic multifactorial polymicrobial infection, characterized by profound modifications of the composition and proportion of the subgingival microbiota. Microbiological laboratory tests are sometimes used in periodontal diagnosis and monitoring of treatment, but both conventional cultivation methods and molecular techniques have some major drawbacks. Therefore, other performant bacterial identification methods must be considered. The aim of the current study was to use Matrix-assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry (MALTI-TOF MS) analysis in association with bacterial culture method to evaluate the modifications of the subgingival bacterial composition in periodontitis patients, before and after cause-related subgingival therapy. Subgingival plaque samples were collected from periodontal pockets before and after subgingival mechanical instrumentation and adjunctive local antimicrobial applications and were cultured in aerobic and anaerobic conditions. Microbial colonies were further assessed using MALDI-TOF-MS. A total of 36 bacterial strains were isolated from a group of 16 patients. All species from the orange complex were identified by MALDI-TOF MS. A marked reduction of detection frequency was observed in most bacterial strains, including the orange complex after cause-related periodontal treatment. The results of this study indicate that MALDI-TOF MS could be considered an accurate method for oral microbial identification and the cause-related periodontal treatment is useful for reducing the microbial burden.

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Dickinson, Danielle N., Myron T. La Duc, William E. Haskins, Igor Gornushkin, James D. Winefordner, David H. Powell e Kasthuri Venkateswaran. "Species Differentiation of a Diverse Suite of Bacillus Spores by Mass Spectrometry-Based Protein Profiling". Applied and Environmental Microbiology 70, n. 1 (gennaio 2004): 475–82. http://dx.doi.org/10.1128/aem.70.1.475-482.2004.

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ABSTRACT In this study, we demonstrate the versatility of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOFMS) protein profiling for the species differentiation of a diverse suite of Bacillus spores. MALDI-TOFMS protein profiles of 11 different strains of Bacillus spores, encompassing nine different species, were evaluated. Bacillus species selected for MALDI-TOFMS analysis represented the spore-forming bacterial diversity of typical class 100K clean room spacecraft assembly facilities. A one-step sample treatment and MALDI-TOFMS preparation were used to minimize the sample preparation time. A library of MALDI-TOFMS spectra was created from these nine Bacillus species, the most diverse protein profiling study of the genus reported to date. Linear correlation analysis was used to successfully differentiate the MALDI-TOFMS protein profiles from all strains evaluated in this study. The MALDI-TOFMS protein profiles were compared with 16S rDNA sequences for their bacterial systematics and molecular phylogenetic affiliations. The MALDI-TOFMS profiles were found to be complementary to the 16S rDNA analysis. Proteomic studies of Bacillus subtilis 168 were pursued to identify proteins represented by the biomarker peaks in the MALDI-TOFMS spectrum. Four small, acid-soluble proteins (A, B, C, and D), one DNA binding protein, hypothetical protein ymf J, and four proteins associated with the spore coat and spore coat formation (coat JB, coat F, coat T, and spoIVA) were identified. The ability to visualize higher-molecular-mass coat proteins (10 to 25 kDa) as well as smaller proteins (<10 kDa) with MALDI-TOFMS profiling is critical for the complete and effective species differentiation of the Bacillus genus.

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Darie-Ion, Laura, Danielle Whitham, Madhuri Jayathirtha, Yashveen Rai, Anca-Narcisa Neagu, Costel C. Darie e Brînduşa Alina Petre. "Applications of MALDI-MS/MS-Based Proteomics in Biomedical Research". Molecules 27, n. 19 (21 settembre 2022): 6196. http://dx.doi.org/10.3390/molecules27196196.

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Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is one of the most widely used techniques in proteomics to achieve structural identification and characterization of proteins and peptides, including their variety of proteoforms due to post-translational modifications (PTMs) or protein–protein interactions (PPIs). MALDI-MS and MALDI tandem mass spectrometry (MS/MS) have been developed as analytical techniques to study small and large molecules, offering picomole to femtomole sensitivity and enabling the direct analysis of biological samples, such as biofluids, solid tissues, tissue/cell homogenates, and cell culture lysates, with a minimized procedure of sample preparation. In the last decades, structural identification of peptides and proteins achieved by MALDI-MS/MS helped researchers and clinicians to decipher molecular function, biological process, cellular component, and related pathways of the gene products as well as their involvement in pathogenesis of diseases. In this review, we highlight the applications of MALDI ionization source and tandem approaches for MS for analyzing biomedical relevant peptides and proteins. Furthermore, one of the most relevant applications of MALDI-MS/MS is to provide “molecular pictures”, which offer in situ information about molecular weight proteins without labeling of potential targets. Histology-directed MALDI-mass spectrometry imaging (MSI) uses MALDI-ToF/ToF or other MALDI tandem mass spectrometers for accurate sequence analysis of peptide biomarkers and biological active compounds directly in tissues, to assure complementary and essential spatial data compared with those obtained by LC-ESI-MS/MS technique.

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Fresnais, Margaux, Esra Yildirim, Seda Karabulut, Dirk Jäger, Inka Zörnig, Julia Benzel, Kristian W. Pajtler et al. "Rapid MALDI-MS Assays for Drug Quantification in Biological Matrices: Lessons Learned, New Developments, and Future Perspectives". Molecules 26, n. 5 (26 febbraio 2021): 1281. http://dx.doi.org/10.3390/molecules26051281.

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Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has rarely been used in the field of therapeutic drug monitoring, partly because of the complexity of the ionization processes between the compounds to be quantified and the many MALDI matrices available. The development of a viable MALDI-MS method that meets regulatory guidelines for bioanalytical method validation requires prior knowledge of the suitability of (i) the MALDI matrix with the analyte class and properties for ionization, (ii) the crystallization properties of the MALDI matrix with automation features, and (iii) the MS instrumentation used to achieve sensitive and specific measurements in order to determine low pharmacological drug concentrations in biological matrices. In the present hybrid article/white paper, we review the developments required for the establishment of MALDI-MS assays for the quantification of drugs in tissues and plasma, illustrated with concrete results for the different steps. We summarize the necessary parameters that need to be controlled for the successful development of fully validated MALDI-MS methods according to regulatory authorities, as well as currently unsolved problems and promising ways to address them. Finally, we propose an expert opinion on future perspectives and needs in order to establish MALDI-MS as a universal method for therapeutic drug monitoring.

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Albrethsen, Jakob. "Reproducibility in Protein Profiling by MALDI-TOF Mass Spectrometry". Clinical Chemistry 53, n. 5 (1 maggio 2007): 852–58. http://dx.doi.org/10.1373/clinchem.2006.082644.

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Abstract Background: Protein profiling with high-throughput sample preparation and MALDI-TOF MS analysis is a new potential tool for diagnosis of human diseases. However, analytical reproducibility is a significant challenge in MALDI protein profiling. This minireview summarizes studies of reproducibility of MALDI protein profiling and current approaches to improve its analytical performance. Methods: The PubMed database was searched using combinations of the following search terms: MALDI, SELDI, reproducibility, variation, precision, peak intensity, quantification, peptide, biomarkers, and proteomics. Acceptance criteria were detailed reports on the reproducibility with MALDI protein profiling and studies describing efforts to improve the analytical performance with this technology. Results: The reported intraexperiment CVs of the peak intensity vary highly between individual protein peaks, with the reported mean CV of the peak intensity varying among studies from 4% to 26%. There is additional interexperiment variation in peak intensity. Current approaches to improve the analytical performance of MALDI protein profiling include automated sample processing, extensive prefractionation strategies, immunocapture, prestructured target surfaces, standardized matrix (co)crystallization, improved MALDI-TOF MS instrument components, internal standard peptides, quality-control samples, replicate measurements, and algorithms for normalization and peak detection. Conclusions: Further evaluation and optimization of MALDI-TOF MS is recommended before use in routine analysis.

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Israr, Muhammad Zubair, Dennis Bernieh, Andrea Salzano, Shabana Cassambai, Yoshiyuki Yazaki e Toru Suzuki. "Matrix-assisted laser desorption ionisation (MALDI) mass spectrometry (MS): basics and clinical applications". Clinical Chemistry and Laboratory Medicine (CCLM) 58, n. 6 (25 giugno 2020): 883–96. http://dx.doi.org/10.1515/cclm-2019-0868.

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AbstractBackgroundMatrix-assisted laser desorption ionisation (MALDI) mass spectrometry (MS) has been used for more than 30 years. Compared with other analytical techniques, it offers ease of use, high throughput, robustness, cost-effectiveness, rapid analysis and sensitivity. As advantages, current clinical techniques (e.g. immunoassays) are unable to directly measure the biomarker; rather, they measure secondary signals. MALDI-MS has been extensively researched for clinical applications, and it is set for a breakthrough as a routine tool for clinical diagnostics.ContentThis review reports on the principles of MALDI-MS and discusses current clinical applications and the future clinical prospects for MALDI-MS. Furthermore, the review assesses the limitations currently experienced in clinical assays, the advantages and the impact of MALDI-MS to transform clinical laboratories.SummaryMALDI-MS is widely used in clinical microbiology for the screening of microbial isolates; however, there is scope to apply MALDI-MS in the diagnosis, prognosis, therapeutic drug monitoring and biopsy imaging in many diseases.OutlookThere is considerable potential for MALDI-MS in clinic as a tool for screening, profiling and imaging because of its high sensitivity and specificity over alternative techniques.

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Ellis, S. R., J. Soltwisch, M. R. L. Paine, K. Dreisewerd e R. M. A. Heeren. "Laser post-ionisation combined with a high resolving power orbitrap mass spectrometer for enhanced MALDI-MS imaging of lipids". Chemical Communications 53, n. 53 (2017): 7246–49. http://dx.doi.org/10.1039/c7cc02325a.

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Coupling laser post-ionisation with a high resolving power MALDI Orbitrap mass spectrometer has realised an up to ∼100-fold increase in the sensitivity and enhanced the chemical coverage for MALDI-MS imaging of lipids relative to conventional MALDI.

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Sparvero, Louis J., Andrew A. Amoscato, C. Edward Dixon, Joseph B. Long, Patrick M. Kochanek, Bruce R. Pitt, Hülya Bayır e Valerian E. Kagan. "Mapping of phospholipids by MALDI imaging (MALDI-MSI): realities and expectations". Chemistry and Physics of Lipids 165, n. 5 (luglio 2012): 545–62. http://dx.doi.org/10.1016/j.chemphyslip.2012.06.001.

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Mareković, Ivana, Zrinka Bošnjak, Marko Jakopović, Zagorka Boras, Mateja Janković e Sanja Popović-Grle. "Evaluation of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry in Identification of Nontuberculous Mycobacteria". Chemotherapy 61, n. 4 (2016): 167–70. http://dx.doi.org/10.1159/000442517.

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Background/Aims: Species-level identification of nontuberculous mycobacteria (NTM) is important in making decisions about the necessity and choice of antimicrobial treatment. The reason is predictable clinical significance and the susceptibility profile of specific NTM species. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is recognized as a diagnostic tool for routine identification of bacteria and yeasts in the clinical laboratory based on protein fingerprint analysis. The aim of the study was to evaluate MALDI-TOF MS in the identification of NTM. Methods: A total of 25 NTM isolates from liquid cultures were identified with both polymerase chain reaction (PCR)-based hybridization assay and MALDI-TOF MS at the University Hospital Center Zagreb. Results: PCR-based hybridization assay identified 96% (24/25) and MALDI-TOF MS 80% (20/25) of tested NTM isolates. Five isolates with no reliable MALDI-TOF MS identification belonged to the Mycobacterium avium-intracellulare complex. Seventy percent (14/20) of NTM isolates successfully identified with MALDI-TOF MS had a score higher than 2.0, indicating reliable species identification. Conclusion: MALDI-TOF MS is a promising tool for the identification of NTM. With a further improvement of the protein extraction protocol, especially regarding the M. avium-intracellulare complex, MALDI-TOF MS could be an additional standard method for identification of NTM.

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Beeman, Katrin, Jens Baumgärtner, Manuel Laubenheimer, Karlheinz Hergesell, Martin Hoffmann, Ulrich Pehl, Frank Fischer e Jan-Carsten Pieck. "Integration of an In Situ MALDI-Based High-Throughput Screening Process: A Case Study with Receptor Tyrosine Kinase c-MET". SLAS DISCOVERY: Advancing the Science of Drug Discovery 22, n. 10 (18 agosto 2017): 1203–10. http://dx.doi.org/10.1177/2472555217727701.

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Mass spectrometry (MS) is known for its label-free detection of substrates and products from a variety of enzyme reactions. Recent hardware improvements have increased interest in the use of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS for high-throughput drug discovery. Despite interest in this technology, several challenges remain and must be overcome before MALDI-MS can be integrated as an automated “in-line reader” for high-throughput drug discovery. Two such hurdles include in situ sample processing and deposition, as well as integration of MALDI-MS for enzymatic screening assays that usually contain high levels of MS-incompatible components. Here we adapt our c-MET kinase assay to optimize for MALDI-MS compatibility and test its feasibility for compound screening. The pros and cons of the Echo (Labcyte) as a transfer system for in situ MALDI-MS sample preparation are discussed. We demonstrate that this method generates robust data in a 1536-grid format. We use the MALDI-MS to directly measure the ratio of c-MET substrate and phosphorylated product to acquire IC50 curves and demonstrate that the pharmacology is unaffected. The resulting IC50 values correlate well between the common label-based capillary electrophoresis and the label-free MALDI-MS detection method. We predict that label-free MALDI-MS-based high-throughput screening will become increasingly important and more widely used for drug discovery.

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Han, Sang-Soo, Young-Su Jeong e Sun-Kyung Choi. "Current Scenario and Challenges in the Direct Identification of Microorganisms Using MALDI TOF MS". Microorganisms 9, n. 9 (9 settembre 2021): 1917. http://dx.doi.org/10.3390/microorganisms9091917.

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MALDI TOF MS-based microbial identification significantly lowers the operational costs because of minimal requirements of substrates and reagents for extraction. Therefore, it has been widely used in varied applications such as clinical, food, military, and ecological research. However, the MALDI TOF MS method is laced with many challenges including its limitation of the reference spectrum. This review briefly introduces the background of MALDI TOF MS technology, including sample preparation and workflow. We have primarily discussed the application of MALDI TOF MS in the identification of microorganisms. Furthermore, we have discussed the current trends for bioaerosol detection using MALDI TOF MS and the limitations and challenges involved, and finally the approaches to overcome these challenges.

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Sousa, Roberto B., Keila S. C. Lima, Caleb G. M. Santos, Tanos C. C. França, Eugenie Nepovimova, Kamil Kuca, Marcos R. Dornelas e Antonio L. S. Lima. "A New Method for Extraction and Analysis of Ricin Samples through MALDI-TOF-MS/MS". Toxins 11, n. 4 (3 aprile 2019): 201. http://dx.doi.org/10.3390/toxins11040201.

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We report for the first time the efficient use of accelerated solvent extraction (ASE) for extraction of ricin to analytical purposes, followed by the combined use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and MALDI-TOF MS/MS method. That has provided a fast and unambiguous method of ricin identification for in real cases of forensic investigation of suspected samples. Additionally, MALDI-TOF MS was applied to characterize the presence and the toxic activity of ricin in irradiated samples. Samples containing ricin were subjected to ASE, irradiated with different dosages of gamma radiation, and analyzed by MALDI-TOF MS/MS for verification of the intact protein signal. For identification purposes, samples were previously subjected to SDS-PAGE, for purification and separation of the chains, followed by digestion with trypsin, and analysis by MALDI-TOF MS/MS. The results were confirmed by verification of the amino acid sequences of some selected peptides by MALDI-TOF MS/MS. The samples residual toxic activity was evaluated through incubation with a DNA substrate, to simulate the attack by ricin, followed by MALDI-TOF MS/MS analyses.

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Montaudo, Giorgio, Filippo Samperi, Maurizio S. Montaudo, Sabrina Carroccio e Concetto Puglisi. "Current Trends in Matrix-Assisted Laser Desorption/Ionization of Polymeric Materials". European Journal of Mass Spectrometry 11, n. 1 (febbraio 2005): 1–14. http://dx.doi.org/10.1255/ejms.718.

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Abstract (sommario):

In the last few years, mass spectrometry has rapidly become indispensable in polymer analysis and complements, in many ways, the structural data provided by nuclear magnetic resonance. Mass spectrometry of polymers is emerging as a revolutionary technique, capable of challenging the techniques and protocols established for years for the characterization of synthetic polymers. Matrix-assisted laser desorption/ionization (MALDI) has become a widely applied method for the structural characterization of synthetic polymers. The primary aim of this review is to illustrate some recent advances in the study of macromolecular systems by MALDI. MALDI allows the identification of repeat units and end groups, the structural analysis of linear and cyclic oligomers and the estimate of composition and sequence for co-polymers. MALDI is also quite useful for the measurement of molar mass and bivariate distributions in polymers and for the detection of self-association in macromolecules, performed by coupling MALDI with size exclusion chromatography (SEC). Recently MALDI has been applied, with remarkable success, to the study of thermal and oxidative processes in polymers and to the characterization of co-polymers obtained by reactive polymer blending. Selected applications of MALDI to polymers are illustrated herewith.

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Neuenschwander, Felix R., Birgit Groß e Sören Schubert. "Rapid Antibiotic Susceptibility Testing of Gram-Negative Bacteria Directly from Urine Samples of UTI Patients Using MALDI-TOF MS". Antibiotics 12, n. 6 (12 giugno 2023): 1042. http://dx.doi.org/10.3390/antibiotics12061042.

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Abstract (sommario):

Urinary tract infections (UTIs) are one of the most common human infections and are most often caused by Gram-negative bacteria such as Escherichia coli. In view of the increasing number of antibiotic-resistant isolates, rapidly initiating effective antibiotic therapy is essential. Therefore, a faster antibiotic susceptibility test (AST) is desirable. The MALDI-TOF MS-based phenotypic antibiotic susceptibility test (MALDI AST) has been used in blood culture diagnostics to rapidly detect antibiotic susceptibility. This study demonstrates for the first time that MALDI AST can be used to rapidly determine antibiotic susceptibility in UTIs directly from patients’ urine samples. MALDI-TOF MS enables the rapid identification and AST of Gram-negative UTIs within 4.5 h of receiving urine samples. Six urinary tract infection antibiotics, including ciprofloxacin, cotrimoxazole, fosfomycin, meropenem, cefuroxime, and nitrofurantoin, were analyzed and compared with conventional culture-based AST methods. A total of 105 urine samples from UTI patients contained bacterial isolates for MALDI AST. The combination of ID and AST by MALDI-TOF allowed us to interpret the result according to EUCAST guidelines. An overall agreement of 94.7% was found between MALDI AST and conventional AST for the urinary tract pathogens tested.

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Ogundairo, Oluwatosin, Oluwatoyin Ayo Farai, Chinedu Paschal Maduka, Chiamaka Chinaemelum Okongwu, Abdulraheem Olaide Babarinde e Olamide Tolulope Sodamade. "Review on MALDI Imaging for Direct Tissue Imaging and its Application in Pharmaceutical Research". International Journal of Research and Scientific Innovation X, n. XII (2024): 130–41. http://dx.doi.org/10.51244/ijrsi.2023.1012011.

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Abstract (sommario):

Matrix-Assisted Laser Desorption/Ionization (MALDI) imaging has emerged as a powerful analytical technique, enabling direct tissue imaging in pharmaceutical research. This review provides an in-depth exploration of the principles, methodologies, and applications of MALDI imaging in the context of studying drug distribution and molecular changes within tissues. provides a structured approach to exploring the principles, methodologies, applications, challenges, and future directions of MALDI Imaging in pharmaceutical research. Each section aims to contribute to a comprehensive understanding of the technique’s significance and potential for transformative contributions to the field. The study begins by elucidating the underlying principles of MALDI imaging, highlighting the role of matrix-assisted laser desorption/ionization in generating spatially resolved mass spectra from biological samples. Special emphasis is placed on advancements in instrumentation and sample preparation techniques that have enhanced the spatial resolution and sensitivity of MALDI imaging. The application of MALDI imaging in pharmaceutical research is comprehensively explored, focusing on its pivotal role in drug development, pharmacokinetic studies, and toxicity assessments. Case studies and examples illustrate how MALDI imaging facilitates the visualization of drug distribution within tissues, offering valuable insights into drug metabolism, biodistribution, and pharmacodynamics.

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Oliveira, Thais Cristina de Assis, Maria Aparecida Vasconcelos Paiva Brito, Marcia Giambiagi-de Marval, Nívea Maria Vicentini e Carla Christine Lange. "Identification of bovine mastitis pathogens using MALDI-TOF mass spectrometry in Brazil". Journal of Dairy Research 88, n. 3 (agosto 2021): 302–6. http://dx.doi.org/10.1017/s0022029921000595.

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Abstract (sommario):

AbstractIn this Research Communication we evaluate the use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify 380 bacteria isolated from cases of bovine mastitis in Brazil. MALDI-TOF MS identifications were compared to previous identifications by biochemical tests and 16S rRNA sequencing. MALDI-TOF MS achieved a typeability of 95.5%. The accuracy of MALDI-TOF MS for the identification of Staphylococcus isolates was 93.2%. The agreement between MALDI-TOF MS and biochemical identification of Streptococcus agalactiae was 96%, however, the agreement between these techniques for identifying other catalase-negative, Gram-positive cocci was lower. Agreement in identifying Gram-negative bacteria at the genus level was 90.5%. Our findings corroborate that MALDI-TOF MS is an accurate, rapid and simple technique for identifying bovine mastitis pathogens. The availability of this methodology in some research institutions would represent a significant step toward increasing the diagnosis and epidemiological studies of bovine mastitis and other animal infectious diseases in Brazil.

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Lippa, Timothy, Nelli I. Taranenko, Coorg R. Prasad e Vladimir M. Doroshenko. "Infrared Matrix-Assisted Laser Desorption/Ionization Quadrupole Ion Trap Mass Spectrometry". European Journal of Mass Spectrometry 8, n. 3 (giugno 2002): 263–71. http://dx.doi.org/10.1255/ejms.498.

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Abstract (sommario):

Performance characteristics of an infrared (IR) matrix-assisted laser desorption/ionization (MALDI) quadrupole ion trap (QIT) mass spectrometer are presented. Both an IR laser and an ultraviolet (UV) laser have been coupled to the MALDI ion source, allowing for a comparative study of the spectra obtained for the same analyte molecules taken at these two wavelengths. The mass range of the QIT instrument was extended by operating it at a frequency as low as 200 kHz. The results presented for small and medium-size peptides demonstrated a lesser degree of analyte ion fragmentation in the case of the IR-MALDI source compared with that obtained using the UV-MALDI source. Due to the fragmentation phenomenon, the mass resolution for cytochrome C ions(MW12384 Da) was an order of a magnitude higher in the case of IR-MALDI compared with the use of UV-MALDI. This phenomenon has been shown to effect the calibration of the trap instrument for higher masses.

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Woods, Katherine, David Beighton e John L. Klein. "Identification of the ‘Streptococcus anginosus group’ by matrix-assisted laser desorption ionization – time-of-flight mass spectrometry". Journal of Medical Microbiology 63, n. 9 (1 settembre 2014): 1143–47. http://dx.doi.org/10.1099/jmm.0.076653-0.

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Abstract (sommario):

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) provides rapid, accurate and cost-effective identification of a range of bacteria and is rapidly changing the face of routine diagnostic microbiology. However, certain groups of bacteria, for example streptococci (in particular viridans or non-haemolytic streptococci), are less reliably identified by this method. We studied the performance of MALDI-TOF MS for identification of the ‘Streptococcus anginosus group’ (SAG) to species level. In total, 116 stored bacteraemia isolates identified by conventional methods as belonging to the SAG were analysed by MALDI-TOF MS. Partial 16S rRNA gene sequencing, supplemented with sialidase activity testing, was performed on all isolates to provide ‘gold standard’ identification against which to compare MALDI-TOF MS performance. Overall, 100 % of isolates were correctly identified to the genus level and 93.1 % to the species level by MALDI-TOF MS. However, only 77.6 % were correctly identified to the genus level and 59.5 % to the species level by a MALDI-TOF MS direct transfer method alone. Use of a rapid in situ extraction method significantly improved identification rates when compared with the direct transfer method (P<0.001). We recommend routine use of this method to reduce the number of time-consuming full extractions required for identification of this group of bacteria by MALDI-TOF MS in the routine diagnostic laboratory. Only 22 % (1/9) of Streptococcus intermedius isolates were reliably identified by MALDI-TOF MS to the species level, even after full extraction. MALDI-TOF MS reliably identifies S. anginosus and Streptococcus constellatus to the species level but does not reliably identify S. intermedius.

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Jagannadham, Medicharla V., e Ramakrishnan Nagaraj. "Detecting the Site of Phosphorylation in Phosphopeptides without Loss of Phosphate Group Using MALDI TOF Mass Spectrometry". Analytical Chemistry Insights 3 (gennaio 2008): ACI.S497. http://dx.doi.org/10.4137/aci.s497.

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Abstract (sommario):

Phosphopeptides with one and four phosphate groups were characterized by MALDI mass spectrometry. The molecular ion of monophosphopeptide could be detected both as positive and negative ions by MALDI TOF with delayed extraction (DE) and in the reflector mode. The tetraphospho peptide could be detected in linear mode. When MS/MS spectra of the monophospho peptides were obtained in a MALDI TOF TOF instrument by CID, b and y ions with the intact phosphate group were observed, in addition the b and y ions without the phosphate group. Our study indicates that it is possible to detect phosphorylated peptides with out the loss of phosphate group by MALDI TOF as well as MALDI TOF TOF instruments with delayed extraction and in the reflector mode.

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36

LEI, DERU, PEIYING CHEN, XUETING CHEN, YUJIE ZONG e XIANGYANG LI. "Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry for Identification of Microorganisms in Clinical Urine Specimens after Two Pretreatments". Polish Journal of Microbiology 70, n. 2 (31 maggio 2021): 207–13. http://dx.doi.org/10.33073/pjm-2021-018.

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Abstract (sommario):

Rapid identification of microorganisms in urine is essential for patients with urinary tract infections (UTIs). Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been proposed as a method for the direct identification of urinary pathogens. Our purpose was to compare centrifugation-based MALDI-TOF MS and short-term culture combined with MALDI-TOF MS for the direct identification of pathogens in urine specimens. We collected 965 urine specimens from patients with suspected UTIs, 211/965 isolates were identified as positive by conventional urine culture. Compared with the conventional method, the results of centrifugation-based MALDI-TOF MS were consistent in 159/211 cases (75.4%), of which 135/159 (84.9%) had scores ≥ 2.00; 182/211 cases (86.3%) were detected using short-term culture combined with MALDI-TOF MS, of which 153/182 (84.1%) had scores ≥ 2.00. There were no apparent differences among the three methods (p = 0.135). MALDI-TOF MS appears to accelerate the microbial identification speed in urine and saves at least 24 to 48 hours compared with the routine urine culture. Centrifugation-based MALDI-TOF MS is characterized by faster identification speed; however, it is substantially affected by the number of bacterial colonies. In contrast, short-term culture combined with MALDI-TOF MS has a higher detection rate but a relatively slow identification speed. Combining these characteristics, the two methods may be effective and reliable alternatives to traditional urine culture.

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Elbehiry, Ayman, Musaad Aldubaib, Adil Abalkhail, Eman Marzouk, Ahmad ALbeloushi, Ihab Moussa, Mai Ibrahem et al. "How MALDI-TOF Mass Spectrometry Technology Contributes to Microbial Infection Control in Healthcare Settings". Vaccines 10, n. 11 (8 novembre 2022): 1881. http://dx.doi.org/10.3390/vaccines10111881.

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Abstract (sommario):

Healthcare settings have been utilizing matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) since 2010. MALDI-TOF MS has various benefits over the conventional method of biochemical identification, including ease of use, speed, accuracy, and low cost. This approach can solve many of the obstacles to identifying bacteria, fungi and viruses. As technology advanced, more and more databases kept track of spectra, allowing species with similar morphological, genotypic, and biochemical traits to be identified. Using MALDI-TOF MS for identification has become more accurate and quicker due to advances in sample preparation and database enrichment. Rapid sample detection and colony identification using MALDI-TOF MS have produced promising results. A key application of MALDI-TOF MS is quickly identifying highly virulent and drug-resistant diseases. Here, we present a review of the scientific literature assessing the effectiveness of MALDI-TOF MS for locating clinically relevant pathogenic bacteria, fungi, and viruses. MALDI-TOF MS is a useful strategy for locating clinical pathogens, however, it also has some drawbacks. A small number of spectra in the database and inherent similarities among organisms can make it difficult to distinguish between different species, which can result in misidentifications. The majority of the time additional testing may correct these problems, which happen very seldom. In conclusion, infectious illness diagnosis and clinical care are being revolutionized by the use of MALDI-TOF MS in the clinical microbiology laboratory.

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Berg, H. E., S. Shannon e A. N. Schuetz. "Anaerobes Direct from Blood Culture Bottles Can Be Identified by Early Matrix-Assisted Laser Desorption Ionization/ Time-of-Flight Mass Spectrometry (MALDI-TOF MS) at 24 Hours or Less". American Journal of Clinical Pathology 154, Supplement_1 (ottobre 2020): S126. http://dx.doi.org/10.1093/ajcp/aqaa161.276.

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Abstract (sommario):

Abstract Introduction/Objective Matrix-assisted laser desorption ionization/ time-of-flight mass spectrometry (MALDI-TOF MS) direct from positive blood culture bottles has facilitated drastic drops in turn-around times for microorganism identification but has been poorly studied for anaerobes. We investigated the ability of MALDI-TOF to provide early anaerobe identification at 4 hours and 18-24 hours of growth on agar from anaerobic blood culture bottles. Additionally, we reviewed medical records of such patients to ascertain impact of early identification on antimicrobial treatment. Methods Over 9 months, we ran MALDI-TOF on early growth from blood cultures positive for growth in BACTEC™ Lytic/ 10 Anaerobic/F bottles. Broth from each bottle was subbed to sheep blood agar (4 hours, 5% CO2) and 2 CDC (BD-BBL™) anaerobic blood agar plates (examined 18-24 hours and 48 hours). Bruker Biotyper® RUO v7854 and Mayo Clinic Custom MALDI-TOF MS libraries were used for identification. Results 144/184 (78%) bottles resulted in growth of aerobic bacteria. Of the remaining bottles with growth of anaerobes, 38 were assessed by early MALDI-TOF. Early MALDI-TOF at 4 hours identified 3 Clostridium perfringens (8%) and an additional 26/38 (68%) isolates at 18-24 hours (both Gram-positive and –negative). Routine 48 hour identification was required for 9 (24%) isolates. In 7 cases, early MALDI-TOF resulted in a change to more appropriate antimicrobial therapy, most often for Bacteroides. Conclusion 29/38 (76%) of anaerobes from blood culture bottles were identified by early MALDI-TOF and reported to the clinician at least 24 hours before routine review of anaerobic sub plates for growth. All C. perfringens and Bacteroides were identified by 4 and 24 hours, respectively. Although early MALDI-TOF resulted in antimicrobial therapy adjustments in a minority of cases, it may allow for more targeted and earlier antimicrobial therapy. Early MALDI-TOF from anaerobic blood culture bottles should be considered for improved patient care and antimicrobial stewardship.

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Westblade, Lars F., Omai B. Garner, Karen MacDonald, Constance Bradford, David H. Pincus, A. Brian Mochon, Rebecca Jennemann et al. "Assessment of Reproducibility of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Bacterial and Yeast Identification". Journal of Clinical Microbiology 53, n. 7 (29 aprile 2015): 2349–52. http://dx.doi.org/10.1128/jcm.00187-15.

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Abstract (sommario):

Matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry (MS) has revolutionized the identification of clinical bacterial and yeast isolates. However, data describing the reproducibility of MALDI-TOF MS for microbial identification are scarce. In this study, we show that MALDI-TOF MS-based microbial identification is highly reproducible and can tolerate numerous variables, including differences in testing environments, instruments, operators, reagent lots, and sample positioning patterns. Finally, we reveal that samples of bacterial and yeast isolates prepared for MALDI-TOF MS identification can be repeatedly analyzed without compromising organism identification.

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Beganovic, Maya, Michael Costello e Sarah M. Wieczorkiewicz. "Effect of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry (MALDI-TOF MS) Alone versus MALDI-TOF MS Combined with Real-Time Antimicrobial Stewardship Interventions on Time to Optimal Antimicrobial Therapy in Patients with Positive Blood Cultures". Journal of Clinical Microbiology 55, n. 5 (22 febbraio 2017): 1437–45. http://dx.doi.org/10.1128/jcm.02245-16.

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Abstract (sommario):

ABSTRACT Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) decreases the time to organism identification and improves clinical and financial outcomes. The purpose of this study was to evaluate the impact of MALDI-TOF MS alone versus MALDI-TOF MS combined with real-time, pharmacist-driven, antimicrobial stewardship (AMS) intervention on patient outcomes. This single-center, pre-post, quasiexperimental study evaluated hospitalized patients with positive blood cultures identified via MALDI-TOF MS combined with prospective AMS intervention compared to a control cohort with MALDI-TOF MS identification without AMS intervention. AMS intervention included: real-time MALDI-TOF MS pharmacist notification and prospective AMS provider feedback. The primary outcome was the time to optimal therapy (TTOT). A total of 252 blood cultures, 126 in each group, were included in the final analysis. MALDI-TOF MS plus AMS intervention significantly reduced the overall TTOT (75.17 versus 43.06 h; P < 0.001), the Gram-positive contaminant TTOT (48.21 versus 11.75 h; P < 0.001), the Gram-negative infection (GNI) TTOT (71.83 versus 35.98 h; P < 0.001), and the overall hospital length of stay (LOS; 15.03 versus 9.02 days; P = 0.021). The TTOT for Gram-positive infection (GPI) was improved (64.04 versus 41.61 h; P = 0.082). For GPI, the hospital LOS (14.64 versus 10.31 days; P = 0.002) and length of antimicrobial therapy 24.30 versus 18.97 days; P = 0.018) were reduced. For GNI, the time to microbiologic clearance (51.13 versus 34.51 h; P < 0.001), the hospital LOS (15.40 versus 7.90 days; P = 0.027), and the intensive care unit LOS (5.55 versus 1.19 days; P = 0.035) were reduced. To achieve optimal outcomes, rapid identification with MALDI-TOF MS combined with real-time AMS intervention is more impactful than MALDI-TOF MS alone.

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Chui, Huixia, Michael Chan, Drexler Hernandez, Patrick Chong, Stuart McCorrister, Alyssia Robinson, Matthew Walker et al. "Rapid, Sensitive, and Specific Escherichia coli H Antigen Typing by Matrix-Assisted Laser Desorption Ionization–Time of Flight-Based Peptide Mass Fingerprinting". Journal of Clinical Microbiology 53, n. 8 (27 maggio 2015): 2480–85. http://dx.doi.org/10.1128/jcm.00593-15.

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Abstract (sommario):

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has gained popularity in recent years for rapid bacterial identification, mostly at the genus or species level. In this study, a rapid method to identify the Escherichia coli flagellar antigen (H antigen) at the subspecies level was developed using a MALDI-TOF MS platform with high specificity and sensitivity. Flagella were trapped on a filter membrane, and on-filter trypsin digestion was performed. The tryptic digests of each flagellin then were collected and analyzed by MALDI-TOF MS through peptide mass fingerprinting. Sixty-one reference strains containing all 53 H types and 85 clinical strains were tested and compared to serotyping designations. Whole-genome sequencing was used to resolve conflicting results between the two methods. It was found that DHB (2,5-dihydroxybenzoic acid) worked better than CHCA (α-cyano-4-hydroxycinnamic acid) as the matrix for MALDI-TOF MS, with higher confidence during protein identification. After method optimization, reference strains representing all 53 E. coli H types were identified correctly by MALDI-TOF MS. A custom E. coli flagellar/H antigen database was crucial for clearly identifying the E. coli H antigens. Of 85 clinical isolates tested by MALDI-TOF MS-H, 75 identified MS-H types (88.2%) matched results obtained from traditional serotyping. Among 10 isolates where the results of MALDI-TOF MS-H and serotyping did not agree, 60% of H types characterized by whole-genome sequencing agreed with those identified by MALDI-TOF MS-H, compared to only 20% by serotyping. This MALDI-TOF MS-H platform can be used for rapid and cost-effective E. coli H antigen identification, especially during E. coli outbreaks.

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Martic, Sanela, John D. Brennan, Michael A. Brook, Suzanne Ackloo e Noemi Nagy. "Towards the development of a covalently tethered MALDI system — A study of allyl-modified MALDI matrixes". Canadian Journal of Chemistry 85, n. 1 (1 gennaio 2007): 66–76. http://dx.doi.org/10.1139/v06-185.

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Abstract (sommario):

An emerging application of matrix-assisted laser desorption ionization (MALDI) mass spectrometry is the analysis of low molecular weight (LMW) compounds, often via coupled liquid chromatography — MALDI-MS methods. However, in many cases, the low molecular weight region of MALDI mass spectra is obscured by the presence of signals originating from the matrix, suggesting that the development of tethered MALDI matrixes may be required to optimize MS performance for such compounds. To gain insight into potential sites for covalent attachment of MALDI matrixes, we have systematically investigated the role played by a variety of functional group motifs in determining matrix efficiency for three common MALDI matrixes, as judged both by total signal intensity and background noise from matrix decomposition for a set of LMW compounds. A series of allyl derivatives of standard matrixes was prepared, and the efficiency of these materials in the MALDI experiment was measured. All modifications of established matrixes, e.g., 2,5-dihydroxybenzoic acid (DHB), α-cyano-4-hydroxycinnamic acid (CHCA), and caffeic acid (CA), or close analogues led to decreased absolute signal intensity and signal-to-background levels. Improved performance was generally observed with (i) the presence of a phenolic group (carboxylic acids were less effective) (ii) crystalline derivatives, and (iii) compounds that had high extinction coefficients at wavelengths near to that of the exciting laser (337 nm). The most interesting derivatives were the O-allyl ether (15) and N-allyl amide (16) of caffeic acid. These compounds did not facilitate signals from all four analytes tested. However, the observed spectra contained fewer signals from the matrix than from the parent compound CA. These compounds demonstrate that functionalization of MALDI matrixes, ultimately leading to tethered matrixes, is possible without jeopardizing signal intensity.Key words: MALDI, protected matrix, phenol, caffeic acid, allyl ether.

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Gorbunov A. Yu. e Podolskaya E. P. "Fabrication of nanoscale multimolecular structures of lanthanum stearate using Langmuir monolayers for laser desorption/ionization mass spectrometry". Technical Physics Letters 48, n. 11 (2022): 29. http://dx.doi.org/10.21883/tpl.2022.11.54885.19320.

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Abstract (sommario):

Matrix-assisted laser desorption/ionization (MALDI) from the surface of nanosized multimolecular structures based on lanthanum stearate monolayers (FLa) has been studied. The presence of FLa on the surface of MALDI target was confirmed experimentally by laser desorption of lanthanum-containing organic ions. MALDI target functionalization with FLa is shown to significantly increase the yield of target peptide ions, with the optimum being achieved at a film thickness of about 6 monolayers. An approach is proposed in a "lab-on-a-plate" format, which allows specific extraction of peptides modified with chlorine-containing compounds and includes the following steps: functionalization of the target surface, metal affinity extraction, matrix deposition and MALDI mass spectrometric analysis. Keywords: mass spectrometry, matrix assisted laser desorption/ionization (MALDI), surface, Langmuir monolayers, metal affinity chromatography.

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Barborini, Emanuele, Giacomo Bertolini, Monica Epifanio, Alexander Yavorskyy, Simone Vinati e Marc Baumann. "Cluster-Assembled Nanoporous Super-Hydrophilic Smart Surfaces for On-Target Capturing and Processing of Biological Samples for Multi-Dimensional MALDI-MS". Molecules 27, n. 13 (30 giugno 2022): 4237. http://dx.doi.org/10.3390/molecules27134237.

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Abstract (sommario):

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) on cluster-assembled super-hydrophilic nanoporous titania films deposited on hydrophobic conductive-polymer substrates feature a unique combination of surface properties that significantly improve the possibilities of capturing and processing biological samples before and during the MALDI-MS analysis without changing the selected sample target (multi-dimensional MALDI-MS). In contrast to pure hydrophobic surfaces, such films promote a remarkable biologically active film porosity at the nanoscale due to the soft assembling of ultrafine atomic clusters. This unique combination of nanoscale porosity and super-hydrophilicity provides room for effective sample capturing, while the hydrophilic-hydrophobic discontinuity at the border of the dot-patterned film acts as a wettability-driven containment for sample/reagent droplets. In the present work, we evaluate the performance of such advanced surface engineered reactive containments for their benefit in protein sample processing and characterization. We shortly discuss the advantages resulting from the introduction of the described chips in the MALDI-MS workflow in the healthcare/clinical context and in MALDI-MS bioimaging (MALDI-MSI).

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Bowman, Andrew P., James Sawicki, Nari N. Talaty, Wayne R. Buck, Junhai Yang e David S. Wagner. "Evaluation of Quantitative Platforms for Single Target Mass Spectrometry Imaging". Pharmaceuticals 15, n. 10 (23 settembre 2022): 1180. http://dx.doi.org/10.3390/ph15101180.

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Abstract (sommario):

(1) Imaging of pharmaceutical compounds in tissue is an increasingly important subsection of Mass Spectrometry Imaging (MSI). Identifying proper target engagement requires MS platforms with high sensitivity and spatial resolution. Three prominent categories of drugs are small molecule drugs, antibody-drug conjugate payloads, and protein degraders. (2) We tested six common MSI platforms for their limit of detection (LoD) on a representative compound for each category: a Matrix-Assisted Laser Desorption/Ionization (MALDI) Fourier Transform Ion Cyclotron, a MALDI-2 Time-of-Flight (ToF), a MALDI-2 Trapped Ion Mobility Spectrometry ToF, a Desorption Electrospray Ionization Orbitrap, and 2 Atmospheric Pressure-MALDI Triple Quadrupoles. Samples were homogenized tissue mimetic models of rat liver spiked with known concentrations of analytes. (3) We found that the AP-MALDI-QQQ platform outperformed all 4 competing platforms by a minimum of 2- to 52-fold increase in LoD for representative compounds from each category of pharmaceutical. (4) AP-MALDI-QQQ platforms are effective, cost-efficient mass spectrometers for the identification of targeted analytes of interest.

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Sogawa, Kazuyuki, Kaori Hayashi, Shota Murata, Katsunori Furuhata e Fumio Nomura. "Clinical application of MALDI biotyping". Electrophoresis Letters 61, n. 2 (2017): 141–44. http://dx.doi.org/10.2198/electroph.61.141.

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47

Paziani, Mario Henrique, Ludmilla Tonani Carvalho, Marcia de Souza Carvalho Melhem, Margarete Teresa Gottardo de Almeida, Maria Emilia Nadaletto Bonifácio da Silva, Roberto Martinez, Cledir Santos e Marcia Regina von Zeska Kress. "First Comprehensive Report of Clinical Fusarium Strains Isolated in the State of Sao Paulo (Brazil) and Identified by MALDI-TOF MS and Molecular Biology". Microorganisms 8, n. 1 (31 dicembre 2019): 66. http://dx.doi.org/10.3390/microorganisms8010066.

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The aim of this study was to compare the performance of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), phenotypic and molecular methods for the identification of Fusarium species complexes isolated from clinical cases in the State of Sao Paulo (Brazil) between the years 2001 and 2017. Sequencing of ITS region of ribosomal DNA and elongation factor 1 alpha gene (ET1α) were used as reference method in the analysis of a total of 108 Fusarium spp. clinical strains isolated from human hosts with superficial and systemic infections. Agreement between MALDI-TOF-MS and molecular data was observed for 97 out of 108 clinical isolates (89.8%), whereas five (4.6%) and six (5.5%) clinical isolates were misidentified and were not identified by MALDI-TOF MS, respectively. ITS region sequences and MALDI-TOF MS mass spectra identified and grouped correctly most of Fusarium clinical isolates at species complex level. This investigation highlights the potential of MALDI-TOF MS technique as a fast and cost-efficient alternative for clinical Fusarium identification. However, MALDI-TOF MS requires a more accurate and larger database. This work is the first comprehensive report for Fusarium population, based on phenotypic analyses, proteomic profile by MALDI-TOF and phylogenetic analyses of Fusarium species complexes isolated from clinical cases in the State of Sao Paulo, Brazil.

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48

Kett, Warren C., e Deirdre R. Coombe. "A structural analysis of heparin‒like glycosaminoglycans using MALDI‒TOF mass spectrometry". Spectroscopy 18, n. 2 (2004): 185–201. http://dx.doi.org/10.1155/2004/392536.

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Mass spectrometry (MS) techniques have spear‒headed the field of proteomics. Recently, MS has been used to structurally analyse carbohydrates. The heparin/heparan sulfate‒like glycosaminoglycans (HLGAGs) present a special set of difficulties for structural analysis because they are highly sulfated and heterogeneous. We have used a matrix‒assisted laser desorption/ionization time of flight mass spectrometry (MALDI‒MS) technique in which heparin fragments are non‒covalently bound to basic peptides of a known mass, so as to limit in‒source desulfation and hence afford an accurate mass. We examined a range of different sized fragments with varying degrees of sulfation. The potential of combining the MALDI‒MS technique with enzymatic digestion to obtain saccharide sequence information on heparin fragments was explored. A disaccharide analysis greatly assists in determining a sequence from MALDI‒MS data. Enzymatic digestion followed by MALDI‒MS allows structural data on heparin fragments too large for direct MALDI‒MS to be obtained. We demonstrate that synthetic sulfated oligosaccharides can also be analysed by MALDI‒MS. There are advantages and limitations with this methodology, but until superior MS techniques become readily accessible to biomedical scientists the MALDI‒MS method provides a means to structurally analyse HLGAG fragments that have therapeutic potential because of their ability to bind to and functionally regulate a host of clinically important proteins.

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49

Harju, Inka, Christoph Lange, Markus Kostrzewa, Thomas Maier, Kaisu Rantakokko-Jalava e Marjo Haanperä. "Improved Differentiation of Streptococcus pneumoniae and Other S. mitis Group Streptococci by MALDI Biotyper Using an Improved MALDI Biotyper Database Content and a Novel Result Interpretation Algorithm". Journal of Clinical Microbiology 55, n. 3 (4 gennaio 2017): 914–22. http://dx.doi.org/10.1128/jcm.01990-16.

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ABSTRACTReliable distinction ofStreptococcus pneumoniaeand viridans group streptococci is important because of the different pathogenic properties of these organisms. Differentiation betweenS. pneumoniaeand closely relatedSreptococcusmitisspecies group streptococci has always been challenging, even when using such modern methods as 16S rRNA gene sequencing or matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry. In this study, a novel algorithm combined with an enhanced database was evaluated for differentiation betweenS. pneumoniaeandS. mitisspecies group streptococci. One hundred one clinicalS. mitisspecies group streptococcal strains and 188 clinicalS. pneumoniaestrains were identified by both the standard MALDI Biotyper database alone and that combined with a novel algorithm. The database update from 4,613 strains to 5,627 strains drastically improved the differentiation ofS. pneumoniaeandS. mitisspecies group streptococci: when the new database version containing 5,627 strains was used, only one of the 101S. mitisspecies group isolates was misidentified asS. pneumoniae, whereas 66 of them were misidentified asS. pneumoniaewhen the earlier 4,613-strain MALDI Biotyper database version was used. The updated MALDI Biotyper database combined with the novel algorithm showed even better performance, producing no misidentifications of theS. mitisspecies group strains asS. pneumoniae. AllS. pneumoniaestrains were correctly identified asS. pneumoniaewith both the standard MALDI Biotyper database and the standard MALDI Biotyper database combined with the novel algorithm. This new algorithm thus enables reliable differentiation between pneumococci and otherS. mitisspecies group streptococci with the MALDI Biotyper.

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Murray, David L., John R. Mills, Maria Alice V. Willrich, David Barnidge, Mindy C. Kohlhagen e Angela Dispenzieri. "A Rapid MALDI-TOF Method for Isotyping and Quantitating M-Proteins in a Single Assay: Longitudinal Comparison to Serum Protein Electrophoresis and Hevylite for Monitoring Patients with Monoclonal Gammopathies". Blood 126, n. 23 (3 dicembre 2015): 1780. http://dx.doi.org/10.1182/blood.v126.23.1780.1780.

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Abstract Background: Current laboratory methods for detection of monoclonal gammopathies include a panel of serum protein electrophoresis (SPEP), immunofixation electrophoresis (IFE) and serum free light chain quantitation (FLC). Our group has recently described a new assay based on matrix assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry (MS) which is capable of detecting, isotyping and quantitating M-proteins in a single assay. The basic principle of the method involves leveraging the unique mass resulting from light chain (LC) Ig gene rearrangement in B-cells. In a similar fashion to SPEP, the mass distribution of LCs after dissociation from their heavy chains can be examined for the presence of an over expressed light chain. In this study we retrospectively compared the MALDI-TOF MS method to SPEP, IFE and Hevylite ratios for monitoring patients with monoclonal gammopathies. Methods: Serum from patients who had at least 1 diagnostic and 4 serial follow-up samples was enriched for IgG, IgA, IgM, kappa and lambda using nanobodies. After disassociating the heavy and light chains by reduction, the five purified samples were spotted onto a Bruker Microflex MALDI plate. Automated acquisition (~10 seconds/sample) was performed and the five LC mass spectra from each enrichment were overlaid. M-proteins were detected, quantitated and isotyped by the presence of distinct peaks (m-spike) within LC mass to charge regions. The serial patient samples were then measured by MALDI-TOF and a comparison of results was made to previous aquired data. The results were then analyze in light of clinical and lab data in order to evaluate the ability of the MALDI-TOF MS method to monitor patients with monoclonal gammopathies. Results: In M-protein positive patient samples, serial dilution revealed MALDI-TOF MS to have ~10-times lower limit of detection than IFE. M-protein isotype in the cohort by MALDI-TOF MS was 100 percent concordant with the isotype from IFE. The MALDI TOF M-protein quantitation was linear over a clinically acceptable range (0.1 to 6 g/dL) and had improved linearity over SPEP at lower M-protein levels. M-proteins quantitation by MALDI-TOF MS compared well with SPEP with a slope of 1.16 (R2 -0.93). Hevylite Ig ratios for each isotype were statistically similar to those from MALDI-TOF MS demonstrating the ability of the MALDI to measure isotype suppression. For some patients, the MALDI method was able to detect M-proteins in patients with normal Hevylite ratios. Finally, the results for each patient were then compared over the course of monitoring. The time evolution change in M-protein concentration was similar among the three methods with the exception of a few samples in which the MALDI-TOF detected residual M-proteins in treated patients not detected by the other methods. Conclusion: This preliminary study demonstrates that MALDI-TOF MS method can provide detection, quantitation and isotyping data suitable for monitoring patients. This is a significant finding since the MALDI-TOF method is amendable to automation, is rapid and in its current format is cost-competitive with current clinical assays. Disclosures Murray: Mayo Clinic: Patents & Royalties: Patent Application Filed. Mills:Mayo Clinci: Patents & Royalties: Patent Application Filed. Barnidge:Mayo Clinic: Patents & Royalties: Patent Application Filed.

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