Longitudinal T1 relaxation rate (R1) captures changes in short-term Mn exposure in welders

Mechelle Lewis, Michael R. Flynn, Eun Young Lee, Scott Van Buren, Eric Van Buren, Guangwei Du, Rebecca C. Fry, Amy H. Herring, Lan Kong, Richard Mailman, Xuemei Huang

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Objectives We demonstrated recently that the T1 relaxation rate (R1) captured short-term Mn exposure in welders with chronic, relatively low exposure levels in a cross-sectional study. In the current study, we used a longitudinal design to examine whether R1 values reflect the short-term dynamics of Mn exposure. Methods Twenty-nine welders were evaluated at baseline and 12 months. Occupational questionnaires estimated short-term welding exposure using welding hours in the 90 days prior to each study visit (HrsW90). In addition, blood Mn levels, the pallidal index (PI; globus pallidus T1-weighted intensity (T1WI)/frontal white matter T1WI), and R1 values in brain regions of interest (ROIs) were determined as Mn biomarkers at each visit. Associations between changes in estimated welding exposure and changes in purported Mn biomarkers were assessed by Spearman's correlations with adjustment for age and baseline R1, HrsW90, and blood Mn values. Results Changes in welding hours (HrsW90: the short-term welding exposure estimate), was associated significantly with changes in R1 values in the putamen (r = 0.541, p = 0.005), caudate (R = 0.453, p = 0.023), globus pallidus (R = 0.430, p = 0.032), amygdala (R = 0.461, p = 0.020), and hippocampus (R = 0.447, p = 0.025), but not with changes in blood Mn levels or the PI. Discussion Changes in R1 values correlated with changes in the short-term welding exposure estimate, but not with more traditional measures of Mn exposure (blood Mn levels or PI). These results suggest that R1 may serve as a useful marker to capture the short-term dynamics in Mn brain accumulation related to welding exposure.

Original languageEnglish (US)
Pages (from-to)39-44
Number of pages6
JournalNeuroToxicology
Volume57
DOIs
StatePublished - Dec 1 2016

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Welding
Blood
Globus Pallidus
Biomarkers
Brain
Putamen
Amygdala
Hippocampus
Cross-Sectional Studies

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Toxicology

Cite this

Lewis, Mechelle ; Flynn, Michael R. ; Lee, Eun Young ; Van Buren, Scott ; Van Buren, Eric ; Du, Guangwei ; Fry, Rebecca C. ; Herring, Amy H. ; Kong, Lan ; Mailman, Richard ; Huang, Xuemei. / Longitudinal T1 relaxation rate (R1) captures changes in short-term Mn exposure in welders. In: NeuroToxicology. 2016 ; Vol. 57. pp. 39-44.
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title = "Longitudinal T1 relaxation rate (R1) captures changes in short-term Mn exposure in welders",
abstract = "Objectives We demonstrated recently that the T1 relaxation rate (R1) captured short-term Mn exposure in welders with chronic, relatively low exposure levels in a cross-sectional study. In the current study, we used a longitudinal design to examine whether R1 values reflect the short-term dynamics of Mn exposure. Methods Twenty-nine welders were evaluated at baseline and 12 months. Occupational questionnaires estimated short-term welding exposure using welding hours in the 90 days prior to each study visit (HrsW90). In addition, blood Mn levels, the pallidal index (PI; globus pallidus T1-weighted intensity (T1WI)/frontal white matter T1WI), and R1 values in brain regions of interest (ROIs) were determined as Mn biomarkers at each visit. Associations between changes in estimated welding exposure and changes in purported Mn biomarkers were assessed by Spearman's correlations with adjustment for age and baseline R1, HrsW90, and blood Mn values. Results Changes in welding hours (HrsW90: the short-term welding exposure estimate), was associated significantly with changes in R1 values in the putamen (r = 0.541, p = 0.005), caudate (R = 0.453, p = 0.023), globus pallidus (R = 0.430, p = 0.032), amygdala (R = 0.461, p = 0.020), and hippocampus (R = 0.447, p = 0.025), but not with changes in blood Mn levels or the PI. Discussion Changes in R1 values correlated with changes in the short-term welding exposure estimate, but not with more traditional measures of Mn exposure (blood Mn levels or PI). These results suggest that R1 may serve as a useful marker to capture the short-term dynamics in Mn brain accumulation related to welding exposure.",
author = "Mechelle Lewis and Flynn, {Michael R.} and Lee, {Eun Young} and {Van Buren}, Scott and {Van Buren}, Eric and Guangwei Du and Fry, {Rebecca C.} and Herring, {Amy H.} and Lan Kong and Richard Mailman and Xuemei Huang",
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Longitudinal T1 relaxation rate (R1) captures changes in short-term Mn exposure in welders. / Lewis, Mechelle; Flynn, Michael R.; Lee, Eun Young; Van Buren, Scott; Van Buren, Eric; Du, Guangwei; Fry, Rebecca C.; Herring, Amy H.; Kong, Lan; Mailman, Richard; Huang, Xuemei.

In: NeuroToxicology, Vol. 57, 01.12.2016, p. 39-44.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Longitudinal T1 relaxation rate (R1) captures changes in short-term Mn exposure in welders

AU - Lewis, Mechelle

AU - Flynn, Michael R.

AU - Lee, Eun Young

AU - Van Buren, Scott

AU - Van Buren, Eric

AU - Du, Guangwei

AU - Fry, Rebecca C.

AU - Herring, Amy H.

AU - Kong, Lan

AU - Mailman, Richard

AU - Huang, Xuemei

PY - 2016/12/1

Y1 - 2016/12/1

N2 - Objectives We demonstrated recently that the T1 relaxation rate (R1) captured short-term Mn exposure in welders with chronic, relatively low exposure levels in a cross-sectional study. In the current study, we used a longitudinal design to examine whether R1 values reflect the short-term dynamics of Mn exposure. Methods Twenty-nine welders were evaluated at baseline and 12 months. Occupational questionnaires estimated short-term welding exposure using welding hours in the 90 days prior to each study visit (HrsW90). In addition, blood Mn levels, the pallidal index (PI; globus pallidus T1-weighted intensity (T1WI)/frontal white matter T1WI), and R1 values in brain regions of interest (ROIs) were determined as Mn biomarkers at each visit. Associations between changes in estimated welding exposure and changes in purported Mn biomarkers were assessed by Spearman's correlations with adjustment for age and baseline R1, HrsW90, and blood Mn values. Results Changes in welding hours (HrsW90: the short-term welding exposure estimate), was associated significantly with changes in R1 values in the putamen (r = 0.541, p = 0.005), caudate (R = 0.453, p = 0.023), globus pallidus (R = 0.430, p = 0.032), amygdala (R = 0.461, p = 0.020), and hippocampus (R = 0.447, p = 0.025), but not with changes in blood Mn levels or the PI. Discussion Changes in R1 values correlated with changes in the short-term welding exposure estimate, but not with more traditional measures of Mn exposure (blood Mn levels or PI). These results suggest that R1 may serve as a useful marker to capture the short-term dynamics in Mn brain accumulation related to welding exposure.

AB - Objectives We demonstrated recently that the T1 relaxation rate (R1) captured short-term Mn exposure in welders with chronic, relatively low exposure levels in a cross-sectional study. In the current study, we used a longitudinal design to examine whether R1 values reflect the short-term dynamics of Mn exposure. Methods Twenty-nine welders were evaluated at baseline and 12 months. Occupational questionnaires estimated short-term welding exposure using welding hours in the 90 days prior to each study visit (HrsW90). In addition, blood Mn levels, the pallidal index (PI; globus pallidus T1-weighted intensity (T1WI)/frontal white matter T1WI), and R1 values in brain regions of interest (ROIs) were determined as Mn biomarkers at each visit. Associations between changes in estimated welding exposure and changes in purported Mn biomarkers were assessed by Spearman's correlations with adjustment for age and baseline R1, HrsW90, and blood Mn values. Results Changes in welding hours (HrsW90: the short-term welding exposure estimate), was associated significantly with changes in R1 values in the putamen (r = 0.541, p = 0.005), caudate (R = 0.453, p = 0.023), globus pallidus (R = 0.430, p = 0.032), amygdala (R = 0.461, p = 0.020), and hippocampus (R = 0.447, p = 0.025), but not with changes in blood Mn levels or the PI. Discussion Changes in R1 values correlated with changes in the short-term welding exposure estimate, but not with more traditional measures of Mn exposure (blood Mn levels or PI). These results suggest that R1 may serve as a useful marker to capture the short-term dynamics in Mn brain accumulation related to welding exposure.

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