{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T20:22:20Z","timestamp":1791836540489,"version":"4.3.4"},"reference-count":105,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2026,1,15]],"date-time":"2026-01-15T00:00:00Z","timestamp":1768435200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100008891","name":"Loma Linda University","doi-asserted-by":"crossref","award":["2170258"],"award-info":[{"award-number":["2170258"]}],"id":[{"id":"10.13039\/100008891","id-type":"DOI","asserted-by":"crossref"}]},{"name":"National Scientific and Technological Research Council","award":["RESOL-2018-2704-APN-DIR#CONICET"],"award-info":[{"award-number":["RESOL-2018-2704-APN-DIR#CONICET"]}]},{"name":"School of Medicine, Adventist University of River Plate, Entre R\u00edos, Argentina"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>N-Acetyl-D-mannosamine (ManNAc) and N-acetylneuraminic acid (Neu5Ac) are important components of glycosylation, affecting numerous physiologic processes. The effects of age, body mass index (BMI), race, or sex on serum levels of ManNAc and Neu5Ac are poorly understood. However, these associations are of substantial interest. Simultaneous quantification of ManNAc and Neu5Ac, using liquid chromatography tandem mass spectrometry (LC-MS\/MS), was developed and validated for human serum samples. This method has high sensitivity, specificity, and reproducibility, with limits of detection as low as 1.02 ng\/mL for ManNAc or 1.14 ng\/mL for Neu5Ac. A set of 155 serum samples from the Adventist Health Study 2 (AHS-2) cohort was analyzed. Concentrations of conjugated Neu5Ac were 35.1 \u00b1 9.4 \u00b5g\/mL and 33.0 \u00b1 9.5 \u00b5g\/mL in black and white participants, respectively. Conjugated and total Neu5Ac levels were significantly higher in women, with p-values of 0.029 and 0.026, respectively. The free forms of Neu5Ac were 594 \u00b1 421 ng\/mL and 439 \u00b1 168 ng\/mL in black and white participants, respectively. Similarly, conjugated and total ManNAc levels were higher in black participants, at 1.81 \u00b1 0.81 \u00b5g\/mL and 1.90 \u00b1 0.83 \u00b5g\/mL, compared to 1.32 \u00b1 0.52 \u00b5g\/mL and 1.41 \u00b1 0.53 \u00b5g\/mL in white participants (both cases, p &lt; 0.001). Free ManNAc was 93.1 \u00b1 36.2 ng\/mL in black and 89 \u00b1 20.2 ng\/mL in white participants. Subjects with higher BMI tend to have higher free ManNAc (p = 0.041). Furthermore, older subjects tend to have higher free (p \u2264 0.001) and total (p = 0.045) ManNAc. The improved LC-MS\/MS quantification method should facilitate further investigations.<\/jats:p>","DOI":"10.3390\/ijms27020894","type":"journal-article","created":{"date-parts":[[2026,1,16]],"date-time":"2026-01-16T08:08:21Z","timestamp":1768550901000},"page":"894","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Simultaneous ManNAc and Neu5Ac Quantification in Human Sera by LC-MS\/MS"],"prefix":"10.3390","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0009-0003-8351-0144","authenticated-orcid":false,"given":"Gerardo N.","family":"Guerrero-Flores","sequence":"first","affiliation":[{"name":"Centro Interdisciplinario de Investigaciones en Ciencias de la Salud y del Comportamiento (CIICSAC), Facultad de Ciencias de la Salud, Universidad Adventista del Plata, 25 de Mayo 99, Libertador San Mart\u00edn 3103, Argentina"},{"name":"Facultad de Ciencias M\u00e9dicas, Universidad Nacional de Rosario (UNR), Rosario 2000, Argentina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fabio J.","family":"Pacheco","sequence":"additional","affiliation":[{"name":"Centro Interdisciplinario de Investigaciones en Ciencias de la Salud y del Comportamiento (CIICSAC), Facultad de Ciencias de la Salud, Universidad Adventista del Plata, 25 de Mayo 99, Libertador San Mart\u00edn 3103, Argentina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0486-7280","authenticated-orcid":false,"given":"Veronica L.","family":"Martinez Marignac","sequence":"additional","affiliation":[{"name":"Centro de Investigaci\u00f3n Cient\u00edfica y de Transferencia Tecnol\u00f3gica a la Producci\u00f3n (CICYTTP-CONICET), Diamante 3105, Argentina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4010-9815","authenticated-orcid":false,"given":"Christopher C.","family":"Perry","sequence":"additional","affiliation":[{"name":"Division of Biochemistry, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1057-7746","authenticated-orcid":false,"given":"Guangyu","family":"Zhang","sequence":"additional","affiliation":[{"name":"Division of Biochemistry, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7986-4551","authenticated-orcid":false,"given":"Martin L.","family":"Mayta","sequence":"additional","affiliation":[{"name":"Centro Interdisciplinario de Investigaciones en Ciencias de la Salud y del Comportamiento (CIICSAC), Facultad de Ciencias de la Salud, Universidad Adventista del Plata, 25 de Mayo 99, Libertador San Mart\u00edn 3103, Argentina"},{"name":"Facultad de Ciencias Bioqu\u00edmicas y Farmac\u00e9uticas, Universidad Nacional de Rosario (UNR), Rosario 2000, Argentina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4096-4926","authenticated-orcid":false,"given":"Josef","family":"Voglmeir","sequence":"additional","affiliation":[{"name":"Glycomics and Glycan Bioengineering Research Center (GGBRC), College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Li","family":"Liu","sequence":"additional","affiliation":[{"name":"Glycomics and Glycan Bioengineering Research Center (GGBRC), College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gary E.","family":"Fraser","sequence":"additional","affiliation":[{"name":"Center for Nutrition, Healthy Lifestyles and Disease Prevention, School of Public Health, Loma Linda University, Loma Linda, CA 92350, USA"},{"name":"Adventist Health Study, Loma Linda University, Loma Linda, CA 92350, USA"},{"name":"Department of Medicine, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fayth M.","family":"Butler","sequence":"additional","affiliation":[{"name":"Center for Nutrition, Healthy Lifestyles and Disease Prevention, School of Public Health, Loma Linda University, Loma Linda, CA 92350, USA"},{"name":"Adventist Health Study, Loma Linda University, Loma Linda, CA 92350, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6919-3726","authenticated-orcid":false,"given":"Danilo S.","family":"Boskovic","sequence":"additional","affiliation":[{"name":"Division of Biochemistry, Department of Basic Sciences, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA"},{"name":"Department of Earth and Biological Sciences, School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"876","DOI":"10.1002\/cpdd.1433","article-title":"Impact of Food on the Oral Absorption of N-Acetyl-D-Mannosamine in Healthy Men and Women","volume":"2024","author":"Evans","year":"2024","journal-title":"Orig. 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