As the lipidomics field continues to advance, self-evaluation within the community is critical. Here, we performed an interlaboratory comparison exercise for lipidomics using Standard Reference Material (SRM) 1950-Metabolites in Frozen Human Plasma, a commercially available reference material. The interlaboratory study comprised 31 diverse laboratories, with each laboratory using a different lipidomics workflow. A total of 1,527 unique lipids were measured across all laboratories and consensus location estimates and associated uncertainties were determined for 339 of these lipids measured at the sum composition level by five or more participating laboratories. These evaluated lipids detected in SRM 1950 serve as community-wide benchmarks for intra- and interlaboratory quality control and method validation. These analyses were performed using nonstandardized laboratory-independent workflows. The consensus locations were also compared with a previous examination of SRM 1950 by the LIPID MAPS consortium. While the central theme of the interlaboratory study was to provide values to help harmonize lipids, lipid mediators, and precursor measurements across the community, it was also initiated to stimulate a discussion regarding areas in need of improvement.

Halogen bonding is a recently rediscovered secondary interaction that shows potential to become a complementary molecular tool to hydrogen bonding in rational drug design and in material sciences. Whereas hydrogen bond symmetry has been the subject of systematic studies for decades, the understanding of the analogous three-center halogen bonds is yet in its infancy. The isotopic perturbation of equilibrium (IPE) technique with (13)C NMR detection was applied to regioselectively deuterated pyridine complexes to investigate the symmetry of [N-I-N](+) and [N-Br-N](+) halogen bonding in solution. Preference for a symmetric arrangement was observed for both a freely adjustable and for a conformationally restricted [N-X-N](+) model system, as also confirmed by computation on the DFT level. A closely attached counterion is shown to be compatible with the preferred symmetric arrangement. The experimental observations and computational predictions reveal a high energetic gain upon formation of symmetric, three-center four-electron halogen bonding. Whereas hydrogen bonds are generally asymmetric in solution and symmetric in the crystalline state, the analogous bromine and iodine centered halogen bonds prefer symmetric arrangement in solution.

Here we report a case of Covid-19-related acute necrotizing encephalopathy (ANE) where SARS-CoV-2 RNA was found in cerebrospinal fluid (CSF) 19 days after symptom onset after testing negative twice. Even though monocytes and protein levels in CSF were only marginally increased, and our patient never experienced a hyperinflammatory state, her neurological function deteriorated into coma. Magnetic resonance imaging of the brain showed pathological signal symmetrically in central thalami, subinsular regions, medial temporal lobes and brain stem. Extremely high concentrations of the neuronal injury markers neurofilament light (NfL) and tau, as well as an astrocytic activation marker, glial fibrillary acidic protein (GFAp), were measured in CSF. Neuronal rescue proteins and other pathways were elevated in the in-depth proteomics analysis. The patient received intravenous immunoglobulins (IVIG) and plasma exchange (PLEX). Her neurological status improved and she was extubated four weeks after symptom onset. This case report highlights the neurotropism of SARS-CoV-2 in selected patients and emphasizes the importance of repeated lumbar punctures and CSF analyses in patients with suspected Covid-19 and neurological symptoms.

Evidence has been obtained that catecholamines and their metabolites are present in single lymphocytes and extracts of T-and B-ceUl clones by use of capiUlary electrophoresis with electrochemical detection. Pharmacological inhibition of tyrosine hydroxylase reduces observed catecholamine levels, suggesting catecholamine synthesis by lymphocytes. Intracelular dopamine levels are shown to be increased by extracellular dopamine, suggesting a cellular-uptake mechanism. Furthermore, incubation with either dopamine or L-dihydroxyphenylalanine, a precursor of dopamine, results in a dosedependent inhibition of lymphocyte proliferation and differentiation. Together, these results suggest the presence of an autocrine loop whereby lymphocytes down-regulate their own activity.

BackgroundKnowledge of the entire protein content, the proteome, of normal human cerebrospinal fluid (CSF) would enable insights into neurologic and psychiatric disorders. Until now technologic hurdles and access to true normal samples hindered attaining this goal.Methods and Principal FindingsWe applied immunoaffinity separation and high sensitivity and resolution liquid chromatography-mass spectrometry to examine CSF from healthy normal individuals. 2630 proteins in CSF from normal subjects were identified, of which 56% were CSF-specific, not found in the much larger set of 3654 proteins we have identified in plasma. We also examined CSF from groups of subjects previously examined by others as surrogates for normals where neurologic symptoms warranted a lumbar puncture but where clinical laboratory were reported as normal. We found statistically significant differences between their CSF proteins and our non-neurological normals. We also examined CSF from 10 volunteer subjects who had lumbar punctures at least 4 weeks apart and found that there was little variability in CSF proteins in an individual as compared to subject to subject.ConclusionsOur results represent the most comprehensive characterization of true normal CSF to date. This normal CSF proteome establishes a comparative standard and basis for investigations into a variety of diseases with neurological and psychiatric features.

High-sensitivity measurement of serum estrogens is important in adult and pediatric endocrinology and oncology. We developed a high-sensitivity liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for simultaneous measurement of estrone (E1) and estradiol (E2). Aliquots of 200 muL of serum were spiked with internal standard, extracted, derivatized with dansyl chloride, and analyzed by LC-MS/MS using 2-dimensional chromatographic separation. Total imprecision for the method was less than 11%; the limit of quantitation was 1 pg/mL. Reference intervals were established with samples from more than 900 healthy postmenopausal women, men, girls, and boys. Concentrations of estrogens in children reached adult levels by Tanner stage 3. In men and postmenopausal women, the median concentrations of total estrogens (E1 + E2) were 39 and 22 pg/mL, and the median E2/E1 ratios were 0.98 and 0.55, respectively. The method requires a small sample volume and has adequate sensitivity and specificity for analyzing estrogens in samples from postmenopausal women, men, and children.

The first investigation of halogen bond symmetry is presented. In contrast to related hydrogen bonds, the iodous halogen bond is symmetric in solution and in the crystal. The bromous analogue is symmetric in solution, but shows asymmetry in the solid state. NMR results are in agreement with DFT predictions.

SUMMARYThe immune and the nervous systems are anatomically closely related and interact with each other by molecules common to both systems, such as cytokines and neurotransmitters. The purpose of this study was to investigate the participation of catecholamines in the neuroimmunological network. The ability of immune cells to produce catecholamines was examined by a highly sensitive capillary electrophoresis assay, which permits detection of easily oxidized catecholamines in the zeptomole (10 ÿ 21 ) range. In addition, the effects of catecholamines on in vitro proliferation, differentiation and apoptosis of lymphocytes were assessed. Mouse spleen cells and macrophages contained on average 7 2 10 ÿ 17 and 2 2 10 ÿ 17 mole dopamine per cell, respectively. In the former cell population also norepinephrine was found. Several mouse B-and T-cell hybridomas were also shown to contain endogenously produced dopamine in levels ranging from 7 2 10 ÿ 20 to 2 2 10 ÿ 18 mole dopamine per cell. In addition, one of the T-cell hybridomas proved to synthesize norepinephrine. The dopamine production of lymphocytes was blocked by the tyrosine hydroxylase inhibitor a -methyl-p-tyrosine, whereas incubation with the precursor L-DOPA increased the dopamine content. Incubation with L-DOPA, dopamine and norepinephrine dose-dependently suppressed mitogen induced proliferation and differentiation of mouse lymphocytes. Even short-time pretreatment of lymphocytes with L-DOPA and dopamine strongly suppressed lymphocyte proliferation and cytokine production. Incubation of lymphoid cells with L-DOPA, dopamine and norepinephrine dose-dependently induced apoptosis which, at least partly, explains the suppressive effects of catecholamines on lymphocyte function. Our results demonstrate that catecholamines: (i) are actively produced by lymphocytes and (ii) have the capacity to act as auto-and/or paracrine regulators of lymphocyte activity through induction of apoptosis.