A two-dimensional HPLC system with electrochemical detection was used for determination of homocysteine, methionine and cysteine enantiomers in biological samples. The amino acid separations were not possible only by using a chiral column. The compounds were separated from each other on an achiral column (Purospher RP-18 endcapped 250-4mm, 5μm) and their enantiomers were separated on Chirobiotic TAG (250-4.6mm, 5μm) column in an on-line system. The mobile phase composition and a choice of electrode potentials for detection were investigated. The l-enantiomers always eluted before the d-enantiomers. The proposed method was applied to the analysis of human serum of healthy volunteers and patients with multiple sclerosis. The limit of detection (LOD) and quantitation (LOQ) were defined as the concentration that produced a signal-to-noise ratio (S/N) of 3 and 10. The method LOD values were found to be between 0.05 and 0.50μgmL(-1). The range of LOQ values were between 0.17 and 1.67μgmL(-1), respectively.
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http://dx.doi.org/10.1016/j.chroma.2015.07.009 | DOI Listing |
Alzheimers Dement
December 2024
Alzheimer's Center at Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA.
Background: Brain endothelial cell (EC) stress, including that induced by vascular amyloid β (Aβ) deposits in cerebral amyloid angiopathy (CAA) and Alzheimer's disease (AD), contributes to cerebral blood flow impairment, blood brain barrier (BBB) damage, neurovascular unit dysfunction, microhemorrhages and hypoperfusion, precipitating neurodegeneration and neuroinflammation processes. Epidemiological and experimental evidence suggests that hyperhomocysteinemia (Hhcy) contributes to increasing AD risk as well as CAA pathology. However, the cellular and molecular mechanisms through which Aβ and Hhcy drive EC and BBB dysfunction, whether the molecular effects of these challenges are additive or independent, and possible therapeutic strategies, remain to be determined.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
University of Massachusetts Chan Medical School, Worcester, MA, USA.
Background: Alzheimer's disease (AD) is the most common type of dementia which results in debilitating memory loss as the disease advances. However, among older adults with AD, some may experience rapid cognitive decline while others may maintain a stable cognitive status for years. In addition to the amyloid plaques, tau tangles, and neuronal inflammation characteristic of AD, there is strong evidence of dysregulation in the peripheral immune system, including decreased naïve T cells and increased memory T cells among older adults with AD.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
The Jackson Laboratory, Bar Harbor, ME, USA.
Background: Mechanisms driving cerebrovascular decline during Alzheimer's disease and related dementias (ADRD) are poorly understood. Methylenetetrahydrofolate reductase (MTHFR) is an enzyme in the folate/methionine pathway. Variants in MTHFR, notably 677C>T, are associated with ADRD.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
Alzheimer's Center at Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA.
Background: The blood-brain barrier (BBB) is a crucial regulator of cerebral homeostasis and function. Cerebrovascular endothelial cells (EC) are important components of the BBB, and EC damage and/or dysfunction may result in defects in brain clearance and perfusion, microhemorrhages, inflammation, and neurodegeneration. In addition to EC damage resulting from the presence of amyloid-beta (Aβ) in Alzheimer's Disease (AD) and Cerebral Amyloid Angiopathy (CAA), the presence of cardiovascular risk factors (CVRF) may further exacerbate cerebrovascular function and neurodegeneration.
View Article and Find Full Text PDFInt J Stroke
January 2025
Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
Background: Covert brain infarction (CBI) is common and poses a potential and non-negligible burden of disease worldwide. The prevalence and risk factors for CBI have been reported inconsistently in previous studies.
Aims: This study aims to ascertain the prevalence and risk factors of CBI and its imaging phenotypes in community-dwelling adults.
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