期刊
NEUROTOXICOLOGY
卷 64, 期 -, 页码 50-59出版社
ELSEVIER
DOI: 10.1016/j.neuro.2017.06.011
关键词
Welders; Manganese; R1; Pallidal index; Fractional anisotropy; Synergy
资金
- National Institutes of Health [R01 ES019672, R01 NS082151]
- Hershey Medical Center General Clinical Research Center (National Center for Advancing Translational Sciences) [UL1 TR000127]
- PA Department of Health Tobacco CURE Funds
Although an essential nutrient, manganese (Mn) can be toxic at high doses. There is, however, uncertainty regarding the effects of chronic low-level Mn-exposure. This review provides an overview of Mn-related brain and functional changes based on studies of a cohort of asymptomatic welders who had lower Mn-exposure than in most previous work. In welders with low-level Mn-exposure, we found: 1) Mn may accumulate in the brain in a non-linear fashion: MRI R1 (1/T1) signals significantly increased only after a critical level of exposure was reached (e.g., >= 300 welding hours in the past 90 days prior to MRI). Moreover, R1 may be a more sensitive marker to capture short-term dynamic changes in Mn accumulation than the pallidal index [T1-weighted intensity ratio of the globus pallidus vs. frontal white matter], a traditional marker for Mn accumulation; 2) Chronic Mn-exposure may lead to microstructural changes as indicated by lower diffusion tensor fractional anisotropy values in the basal ganglia (BG), especially when welding years exceeded more than 30 years; 3) Mn-related subtle motor dysfunctions can be captured sensitively by synergy metrics (indices for movement stability), whereas traditional fine motor tasks failed to detect any significant differences; and 4) Iron (Fe) also may play a role in welding related neurotoxicity, especially at low-level Mn-exposure, evidenced by higher R2* values (an estimate for brain Fe accumulation) in the BG. Moreover, higher R2* values were associated with lower phonemic fluency performance. These findings may guide future studies and the development of occupation- and public health-related polices involving Mn-exposure. (C) 2017 Elsevier B.V. All rights reserved.
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