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document
A randomized cross-over study of inhalation of diesel exhaust , hematological indices , and endothelial markers in humans . BACKGROUND Exposure to traffic-related air pollution ( TRAP ) is considered a trigger for acute cardiovascular events . Diesel Exhaust ( DE ) is a major contributor to TRAP in the world . We evaluated the effect of DE inhalation on circulating blood cell populations , hematological indices , and systemic inflammatory cytokines in humans using a specialized facility . METHODS In a randomized double-blind crossover study balanced to order , 17 metabolic syndrome ( MetS ) and 15 healthy subjects inhaled filtered air ( FA ) or DE exposure in two-hour sessions on different days with a minimum 2-week washout period . We collected blood pre-exposure , 7 , and 22 hours after exposure initiation and measured the complete blood count and differential . We performed multiplex cytokine assay to measure the changes in the systemic inflammatory cytokines , and endothelial adhesion molecules ( n=15 ) . A paired analysis compared the effect of DE and FA exposures for the change from pre-exposure to the subsequent time points . RESULTS A significant increase in the hematocrit was noted 7 hrs after DE [ 1.4 % ( 95 % CI : 0.9 to 1.9 % ) ] compared to FA exposure [ 0.5 % ( 95 % CI : -0.09 to 1.0 % ) ; p=0.008 . The hemoglobin levels increased non-significantly at 7 hrs post DE [ 0.3 gm/dL ( 95 % CI : 0.2 to 0.5 gm/dL ) ] versus FA exposure [ 0.2 gm/dL ( 95 % CI : 0 to 0.3 gm/dL ) ] ; p=0.06 . Furthermore , the platelet count increased 22 hrs after DE exposure in healthy , but not in MetS subjects [ DE : 16.6 ( 95 % CI : 10.2 to 23 ) thousand platelets/mL versus [ FA : 3.4 ( 95 % CI : -9.5 to 16.3 ) thousand platelets/mL ) ] ; p=0.04 . No DE effect was observed for WBC , neutrophils , lymphocytes or erythrocytes . Using the multiplex assay , small borderline significant increases in matrix metalloproteinase-9 , interleukins ( IL ) -1 beta , 6 and 10 occurred 7 hrs post exposure initiation , whereas E-selectin , intercellular adhesion molecule-1 , and vascular cell adhesion molecule -1 , and myeloperoxidase 22 hrs post exposure . CONCLUSIONS Our results suggest that short-term DE exposure results in hemoconcentration and thrombocytosis , which are important determinants of acute cardiovascular events . Multiplex assay showed a non-significant increase in IL-1β and IL-6 immediately post exposure followed by myeloperoxidase and endothelial activation molecules . Further specific assays in a larger population will improve our understanding of the systemic inflammatory mechanisms following acute exposure to TRAP .
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Intervention_Pharmacological
inhaled filtered air ( FA )
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Intervention_Pharmacological
DE exposure
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Outcome_Physical
blood count and differential .
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Outcome_Physical
increase in the hematocrit
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Outcome_Physical
hemoglobin levels increased
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Outcome_Physical
platelet count
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Outcome_Other
DE effect
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Outcome_Physical
WBC , neutrophils , lymphocytes
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Outcome_Physical
erythrocytes .
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Outcome_Physical
increases in matrix metalloproteinase-9 , interleukins ( IL ) -1 beta , 6 and 10
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Outcome_Physical
E-selectin , intercellular adhesion molecule-1
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Outcome_Physical
vascular cell adhesion molecule -1
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Outcome_Physical
myeloperoxidase 22
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Outcome_Physical
hemoconcentration and thrombocytosis
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Participant_Sample-size
17
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Participant_Condition
metabolic syndrome
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Participant_Condition
MetS
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Participant_Sample-size
15