Pallidal index as biomarker of manganese brain accumulation and associated with manganese levels in blood: a meta-analysis.
OBJECTIVE
The current study was designed to evaluate the sensitivity, feasibility, and effectiveness of the pallidal index (PI) serving as a biomarker of brain manganese (Mn) accumulation, which would be used as an early diagnosis criteria for Mn neurotoxicity.


METHODS
The weighted mean difference (WMD) of the PI between control and Mn-exposed groups was estimated by using a random-effects or fixed-effects meta-analysis with 95% confidence interval (CI) performed by STATA software version 12.1. Moreover, the R package "metacor" was used to estimate correlation coefficients between PI and blood Mn (MnB).


RESULTS
A total of eight studies with 281 occupationally Mn-exposed workers met the inclusion criteria. Results were pooled and performed with the Meta-analysis. Our data indicated that the PI of the exposed group was significantly higher than that of the control (WMD: 7.76; 95% CI: 4.86, 10.65; I2 = 85.7%, p<0.0001). A random effects model was used to perform meta-analysis. These findings were remarkably robust in the sensitivity analysis, and publication bias was shown in the included studies. Seven out of the eight studies reported the Pearson correlation (r) values. Significantly positive correlation between PI and MnB was observed (r = 0.42; 95% CI, 0.31, 0.52).


CONCLUSIONS
PI can be considered as a sensitive, feasible, effective and semi-quantitative index in evaluating brain Mn accumulation. MnB can also augment the evaluation of brain Mn accumulation levels in the near future. However, the results should be interpreted with caution.
Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
Shao-Jun
SJ
Li
Department of Radiotherapy, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China.
Li
L
Jiang
School of Health Sciences, Purdue University, West Lafayette, Indiana, United States of America.
Xue
X
Fu
Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
Shuang
S
Huang
Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
Yan-Ni
YN
Huang
Department of Radiology, the First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China.
Xiang-Rong
XR
Li
Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
Jing-Wen
JW
Chen
Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
Yong
Y
Li
Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
Hai-Lan
HL
Luo
Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
Fang
F
Wang
Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
Shi-Yan
SY
Ou
Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, China.
Yue-Ming
YM
Jiang
D001480:Basal Ganglia Diseases / Q000139:chemically induced / Q000473:pathology; D001923:Brain Chemistry; D002986:Clinical Trials as Topic; D005917:Globus Pallidus / Q000737:chemistry*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008345:Manganese / Q000097:blood / Q000493:pharmacokinetics* / Q000633:toxicity; D017895:Manganese Compounds / Q000493:pharmacokinetics; D008452:Maximum Allowable Concentration; D008669:Metallurgy; D016273:Occupational Exposure; D010087:Oxides / Q000493:pharmacokinetics / Q000633:toxicity; D017594:Publication Bias; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D017895:Manganese Compounds; D010087:Oxides; D008345:Manganese; C016552:manganese dioxide