Unilateral Administration of Surface-Modified G1 and G4 PAMAM Dendrimers in Healthy Mice to Assess Dendrimer Migration in the Brain.

Polyamidoamine (PAMAM) dendrimers are nanoparticles that have a wide scope in the field of biomedicine. Previous evidence shows that the generation 4 (G4) dendrimers with a 100% amine surface (G4-NH2) are highly toxic to cells in vitro and in vivo due to their positively charged amine groups. To reduce the toxicity, we modified the surface of the dendrimers to have more neutral functional groups, with 10% of the surface covered with -NH2 and 90% of the surface covered with hydroxyl groups (-OH; G4-90/10). Our previous in vitro data show that these modified dendrimers are taken up by cells, neurons, and different types of stem cells in vitro and neurons and glial cells in vivo. The toxicity assay shows that these modified dendrimers are less toxic compared with G4-NH2 dendrimers. Moreover, prolonged dendrimer exposure (G1-90/10 and G4-90/10), up to 3 weeks following unilateral intrastriatal injections into the striatum of mice, showed that dendrimers have the tendency to migrate within the brain via corpus callosum at different rates depending on their size. We also found that there is a difference in migration between the G1 and G4 dendrimers based on their size differences. The G4 dendrimers migrate in the anterior and posterior directions as well as more laterally from the site of injection in the striatum compared to the G1 dendrimers. Moreover, the G4 dendrimers have unique projections from the site of injection to the cortical areas.

Biomonitoring of Polybrominated Dioxins & Furans, Polychlorinated Dioxins & Furans, and Dioxin Like Polychlorinated Biphenyls in Vietnamese Female Electronic Waste Recyclers.

OBJECTIVE: E-waste is rising globally. This is a follow up to our study reporting metals/polybrominated diphenyl ethers (PBDE's)/polychlorinated biphenyls (PCBs) in female e-waste recyclers. Here we report polybrominated, polychlorinated dioxins/furans, and dioxin-like polychlorinated biphenyls in these same workers. METHODS: Female Vietnamese recyclers and non-recyclers recruited; blood samples collected. Polybrominated, polychlorinated dioxins/furans, and dioxin-like polychlorinated biphenyls levels compared in recyclers, non-recyclers, and National Health and Nutrition Examination Surveys (NHANES). RESULTS: Recyclers >non-recyclers: 12378-PBDD, 2378-TBDF, 12378-PCDF, 123478-HxCDF, 123678-HxCDF, 1234678-HpCDF, PCB-126. Non-recyclers >NHANES: 123478-HxCDF, 123678-HxCDF, 234678- HxCDF, PCB-126, PCB-169. NHANES >non-recyclers: 12378-PCDD, 123478-HxCDD, 123678-HxCDD, 123789-HxCDD, 1234678-HpCDD, 123789-HxCDF, 1234678-HpCDF, 1234789-HpCDF, OCDF, PCB-81, PCB-114, PCB-156, PCB-157, PCB-167, PCB-189. Recyclers >NHANES: S: 2378-TeCDF, 12378-PCDF, 23478-PCDF, 123478-HxCDF, 123678- HxCDF, 234678-HxCDF, PCB-126. NHANES >recyclers: 12378-PCDD, 123478-HxCDD, 123678-HxCDD, 123789-HxCDD, 1234678-HpCDD, OCDD, 123789-HxCDF, 1234678-HpCDF, 1234789-HpCDF, OCDF, PCB- 81, PCB-114, PCB-156, PCB-157, PCB-189. CONCLUSION: 12378 PCDD, 2378-TCDD, PCB 126 makeup most total dioxin equivalences (TEQs) in AQ5 these workers, indicating increased exposure; remediation indicated.

Biomonitoring of Metals, Polybrominated Diphenyl Ethers, Polychlorinated Biphenyls, and Persistent Pesticides in Vietnamese Female Electronic Waste Recyclers.

OBJECTIVE: Electronic waste is increasing. It is frequently recycled in developing countries. This is the first study to report metals, polybrominated diphenyl-ethers (PBDEs), polychlorinated biphenyls (PCBs), 2,2-bis(4-chlorophenyl)-1,1,1-trichloroethane (p,p'-DDT), and p,p'-DDE concentrations in female e-waste workers. METHODS: Female Vietnamese recyclers and non-recyclers were studied. Metals and halogenated organics were measured in blood and urine, and compared with levels in women in the US National Health and Nutrition Examination Survey (NHANES). RESULTS: Recyclers had higher serum PBDE than nonrecyclers. PCB-138/158 and PCB-153 were higher in 18 to less than 38-year-old nonrecyclers. Median urinary arsenic in both cohorts was six to seven-fold higher than NHANES. Median lead in blood and urine was 40% to 60% higher in recyclers than nonrecyclers. Lead in nonrecyclers was four to six-fold higher than NHANES. Both cohorts had higher arsenic and mercury than NHANES. CONCLUSION: Occupational exposure to PBDEs and lead occurred in recyclers. Environmental exposure to arsenic, lead, and mercury occurred in both cohorts. Occupational and environmental remediation are recommended.