Samples of CSF and plasma were obtained simultaneously from 46 adult patients who had no endocrine disorders and were undergoing routine diagnostic lumbar puncture because of suspected or proved prolapse of a disc. Concentrations of 25-OHD, 24,25(OH)2D and 1,25(OH)2D were measured. The samples were purified by column chromatography and fractionated by HPLC. In the appropriate fractions the vitamin D metabolites were measured by PBA, and cytoreceptor assay. The results were as follows (median, range in brackets): 25-OHD in CSF 8.3 ng/ml (2.0-24.8), in plasma 14.5 ng/ml (7.0-36.0). 24,25(OH)2D in CSF 1.8 ng/ml (0.3-4.6) and 2.5 ng/ml (0.4-4.7) in plasma. 1.25(OH)2 D in CSF 25.0 pg/ml (2.2-39.0) and 31.0 pg/ml (10.1-55.0) in plasma. The correlations between plasma and CSF concentrations were as follows: 25-OHD r = 0.479 (P less than 0.001); 24,25(OH)2D r = 0.815 (P less than 0.001) and for 1.25(OH)2D r = 0.497 (P less than 0.001). Our findings showed vitamin D metabolites to be present in human CSF.
Immunoreactive parathyroid hormone-related protein (PTH-rP) was measured in simultaneously obtained cerebrospinal fluid (CSF) and plasma from 51 patients suspected of suffering from a prolapsed intervertebral disc. Endocrine or psychiatric diseases were excluded. In addition, immunoreactive parathyroid hormone (PTH) in the CSF samples was measured. Both, PTH-rP and PTH were assayed by immunoradiometric assay. The results indicate the presence of both, PTH-rP and PTH in CSF. The following concentrations (mean values +/- SD) were found: PTH-rP (pmol/l) in CSF without pleocytosis (n = 17) 0.432 +/- 0.157, with pleocytosis (n = 34) 0.654 +/- 0.675; in plasma (pmol/l) 54.1 +/- 14.632; PTH (nmol/l) in CSF without pleocytosis (n = 17) 0.454 +/- 0.099, with pleocytosis (n = 34) 0.437 +/- 0.140, and in plasma 4.272 +/- 0.794. The concentrations of both, PTH-rP and PTH, in CSF with and without pleocytosis were not significantly different. No correlation was found between PTH-rP and PTH values. The present study demonstrated PTH-rP as a normal constituent in human CSF.
The electrochemical nitrogen reduction reaction (NRR) is a promising alternative to the current greenhouse-gas-emission intensive process to produce ammonia (NH3) from nitrogen (N2). However, finding an electrocatalyst that promotes NRR over the competing hydrogen evolution reaction (HER) has proven to be difficult. This difficulty could potentially be addressed by accelerating the electrocatalyst development for NRR by orders of magnitude using high-throughput (HTP) workflows. In this work, we developed a HTP gas diffusion electrode (GDE) cell to screen up to 16 electrocatalysts in parallel. The key innovation of the cell is the use of expanded Polytetrafluoroethylene (ePTFE) gas diffusion layers (GDL) which simplifies the handling of catalyst arrays compared to carbon fabrics and enables sufficient N2 mass transport. We demonstrate the robustness of the HTP workflow by screening 528 bimetallic catalysts of composition AB (A,B = Ag, Al, Au, Co, Cu, Fe, Mn , Mo, Ni, Pd, Re, Ru, W) for NRR activity. None of the materials produced ammonia significantly over background level which emphasizes the difficulty of finding active electrocatalysts for NRR and narrows down the search space for future studies.
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