Recovery from Welding-Fume-Exposure-Induced MRI T1 Signal Intensities after Cessation of Welding-Fume Exposure in Brains of Cynomolgus Monkeys

Han, Jeong Hee; Chung, Yong Hyun; Park, Jung Duck; Kim, Choong Yong; Yang, Seoung Oh; Khang, Hyun Soo; Cheong, Hae-Kwan; Lee, Jong Seong; Ha, Chang Soo; Song, Chang-Woo; Kwon, Il Hoon; Sung, Jae Hyuck; Heo, Jeong‐Doo; Kim, Nayoung; Huang, Mingai; Cho, Myung‐Haing; Yu, Il Je

doi:10.1080/08958370802116634

Cited by 24 publications

(19 citation statements)

References 14 publications

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“…The behavior changes, measured based on the locomotion time, showed an increase during the weldingfume exposure, followed by a decrease and recovery tendency after the cessation of the welding-fume exposure. The behavior changes corresponded well with the MRI T1 relaxation time (Supplement 2) and blood manganese levels (Supplement 1) measured during the exposure and recovery periods (Han et al, 2008). The periods with a shorter T1 relaxation time and higher blood manganese concentration showed more locomotor activities.…”

Section: Discussionsupporting

confidence: 55%

“…Plus, the manganese accumulation in the globus pallidus was concentration-dependent and the increased T1 image signal intensity reflected the manganese exposure already seen in welders (Kim et al, 1999a) and our previous monkey study (Park et al, 2007). The clearance of accumulated manganese from the brain has also already been reported, where the increased MRI T1 signal intensity was resolved 6 months after the cessation of exposure in welders (Kim et al, 1999b) and 2 months after the cessation of exposure in monkeys (Han et al, 2008). Another study of 111 male welders, smelters and weldingrod manufacturing workers indicated a correlation between an elevated pallidal index (PI), the blood Mn concentration, and a decreased performance in neurological tests (Kim et al, 2005).…”

Section: Introductionmentioning

confidence: 56%

“…The nadir for the shortening of the T1 relaxation time has also been found to correspond well with the blood Mn concentration both in welders and our monkey study (Kim et al, 1999a;Sung et al, 2007), suggesting a correlation between a prolonged high blood Mn concentration and shortened T1 relaxation time. The MRI signal intensities (or shortening of the T1 relaxation time) eventually returned to the pre-exposure levels after the cessation of exposure (Han et al, 2008). Plus, the manganese accumulation in the globus pallidus was concentration-dependent and the increased T1 image signal intensity reflected the manganese exposure already seen in welders (Kim et al, 1999a) and our previous monkey study (Park et al, 2007).…”

Section: Introductionmentioning

confidence: 87%

“…During the 8-month welding-fume exposure period, the locomotor activity of the 6 cynomolgus monkeys was measured on 2 consecutive days during weeks 25 and 32 when the T1 relaxation time was shortened and blood manganese concentrations were increased (Supplements 1 and 2, Han et al, 2008). Despite slight individual differences in the locomotion time, the unexposed monkeys showed normal nocturnal behavior between turning off the light at 7 PM and turning on the light at 7 AM ( Figure 1).…”

Section: Changes In Locomotion Times For Cynomolgus Monkeys During Wementioning

confidence: 96%

“…More than 90% of the fume particles had aerodynamic diameters of less than 1 mm, while the MMAD of the particles and geometric standard deviation were 0.58 mm and 1.49, respectively (Sung et al, 2007). After reaching the peak MRI T1 signal intensity (shortest T1 relaxation time), the monkeys were allowed to recover based on ceasing the welding-fume exposure (Supplement 2, Han et al, 2008). During the recovery period, blood samples were taken every 2 weeks and an MRI scan performed every month.…”

Section: Inhalation Exposure and Recoverymentioning

confidence: 99%

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Home cage locomotor changes in non-human primates after prolonged welding-fume exposure

Kim

Sung

Chung

et al. 2013

Inhalation Toxicology

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To define the relationship between the brain concentration of manganese and neurological signs, such as locomotion, after prolonged welding-fume exposure, cynomolgus monkeys were acclimated for 1 month and then divided into three concentration groups: unexposed, low concentration (31 mg/m(3) total suspended particulate (TSP), 0.9 mg/m(3) of Mn), and high concentration (62 mg/m(3) TSP, 1.95 mg/m(3) of Mn) of TSP. The monkeys were exposed to manual metal-arc stainless steel (MMA-SS) welding fumes for 2 h per day over 8 months in an inhalation chamber system equipped with an automatic fume generator. The home cage locomotor activity and patterns were determined using a camera system over 2-4 consecutive days. After 25 and 32 weeks of exposure, the home cage locomotor activity of the high-concentration primates was found to be 5-6 times higher than that of the unexposed primates, and this increased locomotor activity was maintained for 7 weeks after ceasing the welding-fume exposure, eventually subsiding to three times higher after 13 weeks of recovery. Therefore, the present results, along with our previous observations of a high magnetic resonance imaging (MRI) T1 signal in the globus pallidus and increased blood Mn concentration, indicate that prolonged welding-fume exposure can cause neurobehavioral changes in cynomolgus monkeys.

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Section: Discussionsupporting

confidence: 55%

Section: Introductionmentioning

confidence: 56%

Section: Introductionmentioning

confidence: 87%

Section: Changes In Locomotion Times For Cynomolgus Monkeys During Wementioning

confidence: 96%

Section: Inhalation Exposure and Recoverymentioning

confidence: 99%

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Home cage locomotor changes in non-human primates after prolonged welding-fume exposure

Kim

Sung

Chung

et al. 2013

Inhalation Toxicology

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Regional specificity of manganese accumulation and clearance in the mouse brain: implications for manganese‐enhanced MRI

et al. 2012

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Manganese-enhanced MRI has recently become a valuable tool for the assessment of in vivo functional cerebral activity in animal models. As a result of the toxicity of manganese at higher dosages, fractionated application schemes have been proposed to reduce the toxic side effects by using lower concentrations per injection. Here, we present data on regional-specific manganese accumulation during a fractionated application scheme over 8 days of 30 mg/kg MnCl2 , as well as on the clearance of manganese chloride over the course of several weeks after the termination of the whole application protocol supplying an accumulative dose of 240 mg/kg MnCl2 . Our data show most rapid accumulation in the superior and inferior colliculi, amygdala, bed nucleus of the stria terminalis, cornu ammonis of the hippocampus and globus pallidus. The data suggest that no ceiling effects occur in any region using the proposed application protocol. Therefore, a comparison of basal neuronal activity differences in different animal groups based on locally specific manganese accumulation is possible using fractionated application. Half-life times of manganese clearance varied between 5 and 7 days, and were longest in the periaqueductal gray, amygdala and entorhinal cortex. As the hippocampal formation shows one of the highest T1 -weighted signal intensities after manganese application, and manganese-induced memory impairment has been suggested, we assessed hippocampus-dependent learning as well as possible manganese-induced atrophy of the hippocampal volume. No interference of manganese application on learning was detected after 4 days of Mn(2+) application or 2 weeks after the application protocol. In addition, no volumetric changes induced by manganese application were found for the hippocampus at any of the measured time points. For longitudinal measurements (i.e. repeated manganese applications), a minimum of at least 8 weeks should be considered using the proposed protocol to allow for sufficient clearance of the paramagnetic ion from cerebral tissue.

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Measuring Changes in Brain Manganese or Iron Using Magnetic Resonance Imaging (MRI)

Desmond

Bock

2017

Metals in the Brain

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Recovery from Welding-Fume-Exposure-Induced MRI T1 Signal Intensities after Cessation of Welding-Fume Exposure in Brains of Cynomolgus Monkeys

Cited by 24 publications

References 14 publications

Home cage locomotor changes in non-human primates after prolonged welding-fume exposure

Home cage locomotor changes in non-human primates after prolonged welding-fume exposure

Regional specificity of manganese accumulation and clearance in the mouse brain: implications for manganese‐enhanced MRI

Measuring Changes in Brain Manganese or Iron Using Magnetic Resonance Imaging (MRI)

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