Vitamin B12 and folate deficiency and elevated plasma total homocysteine in workers with chronic exposure to chromate.

OBJECTIVES: Chronic occupational exposure to chromium can result in a broad range of adverse effects including multiple organ damage, genotoxicity and carcinogenesis. However, the metabolic consequences of chromium exposure have not been fully investigated. This study was designed to examine vitamin B12, folate and homocysteine metabolic changes in workers chronically exposed to chromate. The potential association between metabolic alteration and renal impairment induced by chromate exposure was also assessed. METHODS: The level of chromium exposure was evaluated by measuring chromium concentrations in red blood cells (RBC-Cr) and urine (U-Cr). Renal impairment was assessed with serum cystatin C (Cys-C) and urinary ß2-microglobulin (ß2M). Serum vitamin B(12), folate and plasma total homocysteine (tHcy) were measured and correlations analysed. RESULTS: Significant increases in RBC-Cr, U-Cr, serum Cys-C, plasma tHcy and urinary ß2M concentrations were observed in workers chronically exposed to chromate compared to controls. In the exposed workers, serum vitamin B12 and folate levels were decreased and significantly inversely correlated with RBC-Cr concentrations, and increased plasma tHcy concentrations were mirrored by decreased serum vitamin B12 and folate levels. Elevated plasma tHcy concentrations were positively related to serum Cys-C concentrations. CONCLUSIONS: Hyperhomocysteinemia in chronically exposed workers was primarily induced by vitamin B12 and folate deficiency. This metabolic change might be associated with renal dysfunction in chromate processing workers after long term exposure.

[Effect of nano-TiO(2) intratracheal instillation on lipid metabolism of AopE gene-knockout mice].

OBJECTIVE: To investigate the effect of nano-TiO(2) intratracheal instillation on the progression of dyslipidemia and atherosclerosis in apolipoprotein E-knockout mice. METHODS: The nano-TiO(2) was ultrasound with phosphate-buffered saline solutions (PBS) into its suspension for exposure. A total of 46 specific pathogen free (SPF) level of 11-week-old male apolipoprotein E-knockout mice were randomly divided into groups by their body weights: non-treatment group (8 mice), PBS control group (9 mice), high dose group (1.0 mg/ml, 10 mice), medium dose group (0.5 mg/ml, 10 mice), and low dose group (0.1 mg/ml, 9 mice). Except the non-treatment group, mice from other groups were intratracheally instilled with 0.05 ml each time, twice a week. After exposure of 6 weeks, viscera index, blood TC, TG, HDL-C, LDL-C, and organic lipid ratio were assessed as biomarkers. Artery and aortic root issues were assessed by histopathology. RESULTS: After 5 weeks exposure, mice body weights in high dose group ((29.7 ± 1.9) g) started to drop, compared to PBS control ((31.3 ± 1.9) g, t = -1.58, P < 0.05) and low dose group ((31.4 ± 1.4) g, t = -1.17, P < 0.05); after 6 weeks, high dose group ((28.8 ± 1.5) g) was lower than PBS control ((30.4 ± 1.9) g, t = -1.60, P < 0.05), non-treatment group ((30.2 ± 1.3) g, t = -1.43, P < 0.05) and low dose group ((30.6 ± 1.0) g, t = -1.83, P < 0.05). TC levels of non-treatment, PBS control, high dose group, medium dose group and low dose group were (2.92 ± 1.18), (3.12 ± 0.73), (4.19 ± 1.86), (3.46 ± 0.72) and (2.57 ± 0.64) mmol/L, respectively; TG levels were (0.39 ± 0.13), (0.39 ± 0.08), (0.60 ± 0.21), (0.55 ± 0.19) and (0.41 ± 0.11) mmol/L, respectively; HDL-C levels were (1.67 ± 0.45), (1.54 ± 0.67), (0.93 ± 0.50), (1.02 ± 0.48) and (1.31 ± 0.64) mmol/L; TG levels of high dose group were higher than that of non-treatment group (t = 1.27, P = 0.03) and low dose group (t = 1.62, P = 0.01); TG levels of medium dose group was higher than PBS control (t = 0.16, P = 0.04), and TC levels of high dose group were higher than PBS control (t = 0.22, P = 0.01), non-treatment group (t = 0.22, P = 0.04) and low dose group (t = 0.20, P = 0.03), and HDL-C levels of high dose group were lower than PBS control (t = -0.61, P = 0.04) and non-treatment group (t = -0.74, P = 0.04); organic lipid ratio of each group were (2.27 ± 0.51)%, (2.06 ± 0.53)%, (2.90 ± 0.50)%, (2.60 ± 0.23)%, (2.24 ± 0.45)%; high dose group were higher than PBS control (t = 0.85, P = 0.00), non-treatment group (t = 0.64, P = 0.03) and low dose group (t = 0.67, P = 0.01); medium dose group was higher than PBS control (t = 0.54, P = 0.02). The plaque lipid content and calcium content which showed the progression of atherosclerosis and plaque rupture were elevated in medium and high dose groups. CONCLUSION: Intratracheal instillation of nano-TiO(2) can induce dyslipidemia and accelerate the development of atherosclerosis and plaque rupture in ApoE-/-mice.

Using ion-pair reversed-phase HPLC ICP-MS to simultaneously determine Cr(III) and Cr(VI) in urine of chromate workers.

Urinary chromium speciation analysis can provide available information of the individual exposure levels of Cr(VI) compounds. An analytical method based on ion-pair reversed-phase HPLC combined with ICP-MS to simultaneously determine Cr(III) and Cr(VI) in human urine has been developed for assessing the occupational exposure to chromate. The separation conditions of the method, including the pH value, the concentrations of ion-pair reagent and methanol in the mobile phase were studied. Specially, a high-speed polyetheretherketone (PEEK) column and a typical sample introduction method were employed to avoid the exogenous chromium contamination during the analysis. The separation of Cr(III) and Cr(VI) could be finished within 4min with the detection limits as low as 0.03microgL(-1) at 100microL injections for both of them, providing a convenient method for routine analysis of chromium species. The chromium species in urine of chromate workers were monitored using the developed method. The statistical analysis showed a significant relationship (n=32, p<0.01) between the urinary Cr(VI) and the individual airborne exposure levels, indicating that the urinary Cr(VI) could be used as a convenient and suitable monitor for high level Cr(VI) occupational exposure.

[The effects of occupational soluble chromate exposure on immunological function of T-cell].

OBJECTIVE: To investigate the early changes of some immunological function of T-cell in chromate workers. METHODS: A total of 115 workers exposed to different levels of soluble chromate were enrolled in exposed group; while 90 non-exposure workers who lived far away from the chromate plant were enrolled as control. The air concentration of soluble chromate was determined by atomic absorption spectrometry. CD3(+), CD3(+)CD4(+), CD3(+)CD8(+) and CD4(+)/CD8(+) of T-cell were determined by flow cytometry analysis. RESULTS: The individual air chromate concentration in the exposed group was (27.51 +/- 33.25) microg/m(3), and the control group was (0.16 +/- 0.15) microg/m(3). The significant difference between the two groups was observed (z = 8.045, P < 0.01). The levels of the lymphocyte subsets (CD3(+), CD3(+)CD4(+), CD3(+)CD8(+) and CD4(+)/CD8(+)) in exposed group were (30.08 +/- 17.75)%, (1.04 +/- 1.73)%, (11.94 +/- 9.78)%, 0.10 +/- 0.14. While, those of control group were (63.00 +/- 13.57)%, (30.51 +/- 5.16)%, (14.82 +/- 4.59)%, 2.17 +/- 0.53, higher than that of the exposed group (z values were 4.484, 5.227, 1.976, -5.218, respectively, P < 0.05). CONCLUSION: On the basis of individual air monitoring, the cellular immune function affected by soluble chromate is mainly based on T lymphocyte inhibition. The indicators CD3(+)CD4(+) mentioned above may be considered as efficient biomarkers in further research.