1.
Occupational exposure to hexavalent chromium. Part I. Hazard assessment of non-cancer health effects.
Hessel, EVS, Staal, YCM, Piersma, AH, den Braver-Sewradj, SP, Ezendam, J
Regulatory toxicology and pharmacology : RTP. 2021;:105048
-
-
Free full text
-
Abstract
Hexavalent chromium (Cr(VI)) compounds have been studied extensively and several agencies have described their toxicological profile. In the past, personnel of the Dutch Ministry of Defence may have been exposed to Cr(VI) during maintenance activities. To investigate if this exposure may have caused irreversible adverse health effects, the Dutch National Institute for Public Health and the Environment (RIVM) summarized all available knowledge from previous evaluations. This information was complemented with a scoping review to retrieve new scientific literature. All scientific evidence was evaluated in workshops with external experts to come to an overview of irreversible adverse health effects that could be caused by occupational exposure to Cr(VI) compounds. This review focuses on non-cancer health effects. It was concluded that occupational exposure to Cr(VI) can cause perforation of the nasal septum by chromium ulcers, chronic lung diseases, including asthma, rhinitis, pulmonary fibrosis and COPD, skin ulcers and allergic contact dermatitis in humans. It is currently insufficiently clear if Cr(VI) can cause irreversible diseases due to disturbances of the immune system (other than allergic contact eczema, allergic asthma and rhinitis and chronic lung diseases) or adverse effects on fertility or prenatal development in humans.
2.
PBMC fixation and processing for Chromium single-cell RNA sequencing.
Chen, J, Cheung, F, Shi, R, Zhou, H, Lu, W, ,
Journal of translational medicine. 2018;(1):198
Abstract
BACKGROUND Interest in single-cell transcriptomic analysis is growing rapidly, especially for profiling rare or heterogeneous populations of cells. In almost all reported works investigators have used live cells, which introduces cell stress during preparation and hinders complex study designs. Recent studies have indicated that cells fixed by denaturing fixative can be used in single-cell sequencing, however they did not usually work with most types of primary cells including immune cells. METHODS The methanol-fixation and new processing method was introduced to preserve human peripheral blood mononuclear cells (PBMCs) for single-cell RNA sequencing (scRNA-Seq) analysis on 10× Chromium platform. RESULTS When methanol fixation protocol was broken up into three steps: fixation, storage and rehydration, we found that PBMC RNA was degraded during rehydration with PBS, not at cell fixation and up to 3-month storage steps. Resuspension but not rehydration in 3× saline sodium citrate (SSC) buffer instead of PBS preserved PBMC RNA integrity and prevented RNA leakage. Diluted SSC buffer did not interfere with full-length cDNA synthesis. The methanol-fixed PBMCs resuspended in 3× SSC were successfully implemented into 10× Chromium standard scRNA-seq workflows with no elevated low quality cells and cell doublets. The fixation process did not alter the single-cell transcriptional profiles and gene expression levels. Major subpopulations classified by marker genes could be identified in fixed PBMCs at a similar proportion as in live PBMCs. This new fixation processing protocol also worked in several other fixed primary cell types and cell lines as in live ones. CONCLUSIONS We expect that the methanol-based cell fixation procedure presented here will allow better and more effective batching schemes for a complex single cell experimental design with primary cells or tissues.