Cadmium induces bone loss and inhibits bone formation in male mice / 中国职业医学

OBJECTIVE: To explore the effect of cadmium on bone formation and its mechanism in male mice. METHODS: i) The specific pathogen-free C57 BL/6 J wild-type male mice were divided into control group and cadmium exposure group, with 10 mice in each group. Mice in the cadmium exposure group were intraperitoneally injected with 2 mg/kg body weight cadmium chloride twice a week for eight weeks, and mice in the control group were intraperitoneally injected with the same amount of 0.9% sodium chloride solution. After that, the bone mineral density and bone microstructure of the femur of mice were detected by a high-resolution microcomputed tomography scanner. ii) Human SV40-transfected osteoblast cells(hFOB1.19) were divided into control group and cadmium exposure group. The cadmium exposure group was treated with 0.5 μmol/L cadmium chloride solution, cells in the control group were given an equal volume of α-low-limit minimal medium. After culture, the differentiation and mineralization ability of hFOB1.19 cells were analyzed by alkaline phosphatase(ALP) and alizarin red staining, respectively. Cell viability was examined by CCK-8 assay. The protein expression of Janus kinase 2(JAK2), total signal of transducers and activator of transcription 3(tSTAT3) and phosphorylated signal transducers and activator of transcription 3(pSTAT3) was detected by Western blotting. The expression of osteoblastic marker genes ALP, Runt-related transcription factor 2(RUNX2) and osteocalcin(OCN) was detected by real-time quantitative polymerase chain reaction.RESULTS: Compared with the control group, the average bone mineral density decreased(P<0.01), bone volume fraction decreased(P<0.05), the bone trabecula thickness became thinner(P<0.01), the number of bone trabecula decreased(P<0.05), trabecular bone spacing increased(P<0.05) in the femur of mice in cadmium exposure group. The viability of hFOB1.19 cells was decreased [(100.0±10.8)% vs(49.1±8.2)%, P<0.01]. The differentiation ability of osteoblasts was reduced and the mineralization was inhibited. The relative expression levels of JAK2 and pSTAT3 in cells decreased(all P<0.05) and the relative expression levels of osteoblast marker genes ALP, RUNX2 and OCN decreased(all P<0.01).CONCLUSION: Cadmium can induce mice bone loss, which may be due to its inhibition of osteoblastic function by reducing the expression of JAK2 and STAT3 proteins.

[MgO-Biochar for the Adsorption of Phosphate in Water].

A novel composite material MgO-biochar (MgO-BC) with the peanut shells as the precursors was successfully fabricated by loading magnesium oxide (MgO) on the surface of biochar (BC) at high temperature and in oxygen-limited atmosphere. The adsorption characteristics of the resultant adsorbent toward phosphate from aqueous solution were investigated by evaluating the influences of pH, contact time and coexisting ions. The results showed that the best phosphate adsorption onto MgO-BC happened in the pH range of 7-9, and strong acidic or basic media was unfavorable to the phosphate adsorption. Phosphate adsorption process could reach equilibrium within 540 min, and the kinetics curve could be well fitted by both pseudo-first and pseudo-second models. The related coefficients were 97.3% and 99.0%. MgO-BC exhibited highly selective capacity toward phosphate in the presence of competing Cl-, HCO3- and NO3- at 10 times higher concentration than the phosphate concentration. In addition, phosphate adsorption onto MgO-BC could be described satisfactorily by Langmuir model with a fitting coefficient of higher than 99%, and the maximal adsorption capacity calculated by Langmuir equation was 138.07 mg·g-1. The adsorption capacity of phosphate by MgO-BC was much higher than the unmodified BC and other biochar-based sorbents. Furthermore, the composite material after the adsorption of phosphate could also be used as a fertilizer into the soil. It achieved the reuse of the discarded phosphate. All the results validated that MgO-BC has a wide application prospect for the phosphate cleanup from the actual wastewater.

[Sorption characteristics of tea waste modified by hydrated ferric oxide toward Pb(II) in water].

Hydrated ferric oxide was successfully impregnated onto tea waste by precipitation to obtain a new sorbent named HFO-TW, the adsorption characteristics of which toward Pb(II) in aqueous solution was investigated by evaluating the effects of pH value, contact time, coexisting ion, temperature, and initial concentration of Pb(II). The Pb(II) sorption onto HFO-TW was pH- dependent, and the higher pH value was more helpful for Pb(II) adsorption onto HFO-TW in the pH range of 2.5-7. Lead sorption speed was quick and could reach equilibrium within 100 min, and the kinetics curve could be fitted well by both pseudo-first and pseudo-second models. The related coefficient was 98.8%. HFO-TW exhibited highly selective lead retention and the adsorption capacity of Pb(II) onto HFO-TW was declined by only 12.1 mg · g(-1) and 8.1 mg · g(-1) in the presence of competing Ca(II), Mg(II) at 50 times of the target ion. In addition, Pb(II) sorption onto HFO-TW could be described satisfactorily by Langmuir model, and the maximal sorption capacity calculated by Langmuir equation was 89.43 mg · g(-1), which was much higher than the unmodified tea waste and other bio-sorbents. All the results validated that HFO-TW was a promising sorbent for removal of lead from waters.