ABSTRACT
OBJECTIVE: To explore the effect of occupational aluminum exposure on the blood of male workers. METHODS: A total of 249 male workers were selected as the research subjects by cluster sampling method in the electrolytic workshop of an aluminum plant. Blood samples were collected for determination of the blood aluminum concentration and blood routine. The subjects were divided into low-, medium-, and high-aluminuml groups based on the tertile of blood aluminum level(P_(33) is 13.9 μg/L, P_(67) is 37.7 μg/L). RESULTS: The red blood cell(RBC) count and hemoglobin level in patients of the high-aluminum group were lower than that of the low-aluminum group(P<0.05). There was no significant difference of the RBC count and hemoglobin level of patients in middle-aluminum group compared with that of the low-and high-aluminum groups(P>0.05). There was no statistical significant difference in white blood cell count and platelet count among the three groups(P>0.05). The results of the generalized linear regression model showed that the higher the blood aluminum level, the lower the RBC count and hemoglobin level of workers(P<0.05) after eliminating confounding factors such as age, length of service, education level, smoking, and drinking. CONCLUSION: Occupational aluminum exposure can cause a decrease of RBC count and hemoglobin level with a dose-effect relationship in workers.
ABSTRACT
OBJECTIVE: To explore the mechanism of ubiquitin-proteasome pathway(UPP) in the degradation of hyperphosphorylated tau protein in aluminum-induced mouse neuroblastoma N2 a cells. METHODS: N2 a cells in logarithmic growth period were randomly divided into control group and MG132 group. Cells in control group were exposed to concentrations of 0 or 1 mmol/L aluminum chloride for 24 hours. Cells in MG132 group were pretreated with MG132 at a concentration of 5 μmol/L for 6 hours, then exposed to concentrations of 0 or 1 mmol/L aluminum chloride for 24 hours. After exposure, the cells were collected. Western blotting was used to detect the relative expression of tau-5, P-tau181, P-tau231, P-tau262, P-tau396, heat shock protein 70(Hsp70) and carboxyl terminus of the Hsp70-interacting protein(CHIP). The ubiquitin relative expression was detected by enzyme-linked immunosorbent assay. RESULTS: The results of factorial analysis showed that the relative expression of tau-5, P-tau231, P-tau262, P-tau396, CHIP, Hsp70 and ubiquitin in N2 a cells were statistically significant in the main effect and interaction effect of aluminum chloride and MG132 treatment(P<0.05). Both in the control group and MG132 group, the relative expression of tau-5, P-tau231, P-tau262, P-tau396, CHIP, Hsp70 and ubiquitin in N2 a cells exposed to 1 mmol/L aluminum chloride increased(P<0.05) when compared with the N2 a cells without exposed to aluminum chloride. No matter aluminum chloride exposed or not, the relative expression of tau-5, P-tau231, P-tau262, P-tau396, CHIP, Hsp70 and ubiquitin in N2 a cells of MG132 group was higher than that of control group(P<0.05). CONCLUSION: UPP is involved in the regulation of hyperphosphorylated tau protein by proteasome degradation in aluminum-induced N2 a cells. UPP mainly regulates P-tau231, P-tau262, and P-tau396 sites. CHIP and Hsp70 played an important role in the UPP pathway.