- Browse by Subject
Browsing by Subject "manganese"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Association of exposure to manganese and iron with relaxation rates R1 and R2*- magnetic resonance imaging results from the WELDOX II study(Elsevier, 2017) Pesch, Beate; Dydak, Ulrike; Lotz, Anne; Casjens, Swaantje; Quetscher, Clara; Lehnert, Martin; Abramowski, Jessica; Stewig, Christoph; Yeh, Chien-Lin; Weiss, Tobias; van Thriel, Christoph; Herrmann, Lennard; Muhlack, Siegfried; Woitalla, Dirk; Glaubitz, Benjamin; Schmidt-Wilcke, Tobias; Brüning, Thomas; Department of Radiology and Imaging Sciences, School of MedicineObjective Magnetic resonance imaging is a non-invasive method that allows the indirect quantification of manganese (Mn) and iron (Fe) accumulation in the brain due to their paramagnetic features. The WELDOX II study aimed to explore the influence of airborne and systemic exposure to Mn and Fe on the brain deposition using the relaxation rates R1 and R2* as biomarkers of metal accumulation in regions of interest in 161 men, including active and former welders. Material and methods We obtained data on the relaxation rates R1 and R2* in regions that included structures within the globus pallidus (GP), substantia nigra (SN), and white matter of the frontal lobe (FL) of both hemispheres, as well as Mn in whole blood (MnB), and serum ferritin (SF). The study subjects, all male, included 48 active and 20 former welders, 41 patients with Parkinson's disease (PD), 13 patients with hemochromatosis (HC), and 39 controls. Respirable Mn and Fe were measured during a working shift for welders. Mixed regression models were applied to estimate the effects of MnB and SF on R1 and R2*. Furthermore, we estimated the influence of airborne Mn and Fe on the relaxation rates in active welders. Results MnB and SF were significant predictors of R1 but not of R2* in the GP, and were marginally associated with R1 in the SN (SF) and FL (MnB). Being a welder or suffering from PD or HC elicited no additional group effect on R1 or R2* beyond the effects of MnB and SF. In active welders, shift concentrations of respirable Mn > 100 μg/m3 were associated with stronger R1 signals in the GP. In addition to the effects of MnB and SF, the welding technique had no further influence on R1. Conclusions MnB and SF were significant predictors of R1 but not of R2*, indicative of metal accumulation, especially in the GP. Also, high airborne Mn concentration was associated with higher R1 signals in this brain region. The negative results obtained for being a welder or for the techniques with higher exposure to ultrafine particles when the blood-borne concentration was included into the models indicate that airborne exposure to Mn may act mainly through MnB.Item Reversibility of Neuroimaging Markers Influenced by Lifetime Occupational Manganese Exposure(Oxford Academic, 2019-11) Edmondson, David A.; Ma, Ruoyun E.; Yeh, Chien-Lin; Ward, Eric; Snyder, Sandy; Azizi, Elham; Zauber, S Elizabeth; Wells, Ellen M.; Dydak, Ulrike; Radiology and Imaging Sciences, School of MedicineManganese (Mn) is a neurotoxicant that many workers are exposed to daily. There is limited knowledge about how changes in exposure levels impact measures in magnetic resonance imaging (MRI). We hypothesized that changes in Mn exposure would be reflected by changes in the MRI relaxation rate R1 and thalamic γ-aminobutyric acid (GABAThal). As part of a prospective cohort study, 17 welders were recruited and imaged on 2 separate occasions approximately 2 years apart. MRI relaxometry was used to assess changes of Mn accumulation in the brain. Additionally, GABA was measured using magnetic resonance spectroscopy in the thalamic and striatal regions of the brain. Air Mn exposure ([Mn]Air) and cumulative exposure indexes of Mn (Mn-CEI) for the past 3 months (Mn-CEI3M), past year (Mn-CEI12M), and lifetime (Mn-CEILife) were calculated using personal air sampling and a comprehensive work history, whereas toenails were collected for analysis of internal Mn body burden. Finally, welders’ motor function was examined using the Unified Parkinson’s Disease Rating Scale (UPDRS). Median exposure decreased for all exposure measures between the first and second scan. ΔGABAThal was significantly correlated with ΔMn-CEI3M (ρ = 0.66, adjusted p = .02), ΔMn-CEI12M (ρ = 0.70, adjusted p = .006), and Δ[Mn]Air (ρ = 0.77, adjusted p = .002). ΔGABAThal significantly decreased linearly with ΔMn-CEI3M (quantile regression, β = 15.22, p = .02) as well as Δ[Mn]Air (β = 1.27, p = .04). Finally, Mn-CEILife interacted with Δ[Mn]Air in the substantia nigra where higher Mn-CEILife lessened the ΔR1 per Δ[Mn]Air (F-test, p = .005). Although R1 and GABA changed with Mn exposure, UPDRS was unaffected. In conclusion, our study shows that effects from changes in Mn exposure are reflected in thalamic GABA levels and brain Mn levels, as measured by R1, in most brain regions.