An interface for sensitive analysis of monoamine neurotransmitters by ion-pair chromatography-electrospray ionization-mass spectrometry with continuous online elimination of ion-pair reagents

Bioanalytical validation and clinical application of a liquid chromatography-tandem mass spectrometry method for the quantification of 3-orthomethyldopa, 5-hydroxytryptophan, 5-hydroxyindolacetic acid and homovanillic acid in human cerebrospinal fluid

Inherited disorders of monoamine neurotransmitters are a subset of inborn errors of metabolism affecting biochemical pathways of catecholamines, serotonin or their enzymatic cofactors. Usually, their clinical presentation is similar to those of other common neurological syndromes. For this reason, they are frequently under-recognized and misdiagnosed. Because cerebrospinal fluid concentration of catecholamine metabolites (3-orthomethyldopa and homovanillic acid) and serotonin metabolites (5-hydroxytryptophan and 5-hydroxyindolacetic acid) presents a direct correlation with their brain levels, analysis of this group of compounds is critical to reach an accurate diagnosis. Although there are several published liquid chromatography-based bioanalytical methods for the quantification of these compounds, most of them present disadvantages, making their application difficult to implement in routine clinical practice. In this study, a rapid and simple UHPLC-MS/MS method for simultaneous quantification of 3-orthomethyldopa, 5-hydroxytryptophan, 5-hydroxyindolacetic acid and homovanillic acid in human cerebrospinal fluid was validated. All the evaluated performance parameters, including linearity, carryover, accuracy and precision (within and between-day), lower limit of quantitation, recovery, matrix effect and stability under different conditions met the acceptance criteria from international guidelines. Additionally, 10 human cerebrospinal fluid samples collected via lumbar puncture from 10 pediatric patients were quantified using the validated method to assess its clinical application and diagnostic utility for inherited monoamine neurotransmitter metabolism.

Development of Dopamine Sensor Using Silver Nanoparticles and PEG-Functionalized Tapered Optical Fiber Structure

This article presents a localized surface plasmon resonance (LSPR) phenomenon based optical fiber sensor (OFS) for the detection of dopamine (DA). DA functions as a hormone and a neurotransmitter in the human body and plays a crucial role in the peripheral system. To develop the OFS for DA detection, taper fiber probe was fabricated and immobilized with silver nanoparticles (AgNPs) and functionalized with Polyethylene glycol (PEG). The developed sensor shows the great selectivity in the presence of ascorbic acid (AA) oxidation due to PEG coating. The morphology of the AgNPs and uniformity of coating over the surface of sensing probe were confirmed with UV-visible spectrophotometer, transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscope (SEM). The calibration curve is found to be linear over the range of 10 nM-1 μM with the lowest detection limit of 0.058 μM. Also provides a wide dynamic range of detection (10 nm-100 μM). The parameters responsible for the performance of OFS, such as sensitivity, detection limit, and selectivity are greatly improved in the proposed sensor. The applicability of the proposed sensor has been validated and have the potential to use for routine diagnosis.

Pharmacodynamic and urinary metabolomics studies on the mechanism of Schisandra polysaccharide in the treatment of Alzheimer's disease

This study was designed to investigate the antagonism of SCP in Aβ25–35-induced AD rats by intervening in neurotransmitters and metabolites.

Development and validation of a liquid chromatography tandem mass spectrometry method for the measurement of urinary catecholamines in diagnosis of pheochromocytoma

The measurement of catecholamines in human body fluids is requested frequently for the differential diagnosis and monitoring of pheochromocytoma. The methods in most clinical laboratories focus on high-performance liquid chromatography coupled with electrochemical detection, which suffers from high background noise, low sensitivity, and poor separation. We reported and developed a robust high-throughput liquid chromatography tandem mass spectrometry method in routine clinical laboratories for the measurement of urinary catecholamines for diagnosis of pheochromocytoma. The method was validated for consistent linearity, good recovery (88-112%), excellent stability and low carryover. Intra- and inter-assay precision values for catecholamines were all below 3.35 and 4.83% respectively. Dilution linearity was investigated with satisfactory linearly dependent coefficients (r > 0.9988). The reference intervals were obtained from 310 results derived from patients in which the diagnosis of pheochromocytoma was excluded. This method was successfully used in our laboratory. The clinical characteristics of patients have been explored with satisfactory sensitivity and specificity. Therefore, we have developed a reliable assay for the liquid chromatography tandem mass spectrometry measurement of catecholamines in a routine clinical laboratory. The assay requires a small volume of urine, and all analytes are measured simultaneously. The assay is rapid and reliable to be executed, offering the potential for routine clinical laboratories.