Comparison of high MRI T1 signals with manganese concentration in brains of cynomolgus monkeys after 8 months of stainless steel welding-fume exposure.
Several pharmacokinetic studies on inhalation exposure to manganese (Mn) have already demonstrated that Mn readily accumulates in the olfactory and brain regions. However, a shortening of the magnetic resonance imaging (MRI) T1 relaxation time or high T1 signal intensity in specific sites of the brain, including the globus pallidus and subcortical frontal white matter, as indicative of tissue manganese accumulation has not yet been clearly established for certain durations of known doses of welding-fume exposure in experimental animals. Accordingly, to investigate the movement of manganese after welding-fume exposure, six cynomolgus monkeys were acclimated and assigned to three dose groups: unexposed, low dose (31 mg/m(3) total suspended particulate [TSP], 0.9 mg/m(3) of Mn), and high dose (62 mg/m(3) TSP, 1.95 mg/m(3) of Mn) of total suspended particulate. The primates were exposed to manual metal arc stainless steel (MMA-SS) welding fumes for 2 h per day in an inhalation chamber system equipped with an automatic fume generator. Magnetic resonance imaging (MRI) studies were conducted before the initiation of exposure and thereafter every month. The tissue Mn concentrations were then measured after a plateau was reached regarding the shortening of the MRI T1 relaxation time. A dose-dependent increase in the Mn concentration was found in the lungs, while noticeable increases in the Mn concentrations were found in certain tissues, such as the liver, kidneys, and testes. Slight increases in the Mn concentrations were found in the caudate, putamen, frontal lobe, and substantia nigra, while a dose-dependent noticeable increase was only found in the globus pallidus. Therefore, the present results indicated that a shortening of the MRI T1 relaxation time corresponded well with the Mn concentration in the globus pallidus after prolonged welding-fume exposure.
Park
Jung Duck
JD
College of Medicine, Chung-Ang University, Seoul, Korea.
Chung
Yong Hyun
YH
Kim
Choong Yong
CY
Ha
Chang Soo
CS
Yang
Seoung Oh
SO
Khang
Hyun Soo
HS
Yu
In Kyu
IK
Cheong
Hae Kwan
HK
Lee
Jong Seong
JS
Song
Chang-Woo
CW
Kwon
Il Hoon
IH
Han
Jeong Hee
JH
Sung
Jae Hyuck
JH
Heo
Jeong Doo
JD
Choi
Byung Sun
BS
Im
Ruth
R
Jeong
Jayoung
J
Yu
Il Je
IJ
D000395:Air Pollutants, Occupational / Q000009:adverse effects / Q000493:pharmacokinetics*; D000818:Animals; D001273:Atmosphere Exposure Chambers / Q000009:adverse effects; D001921:Brain / Q000378:metabolism*; D005917:Globus Pallidus / Q000378:metabolism; D008252:Macaca fascicularis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008345:Manganese / Q000008:administration & dosage / Q000378:metabolism*; D013193:Stainless Steel / Q000009:adverse effects / Q000493:pharmacokinetics*; D013995:Time; D014896:Welding
D000395:Air Pollutants, Occupational; D013193:Stainless Steel; D008345:Manganese