Bioaccessibility of microplastic-associated heavy metals using an in vitro digestion model and its implications for human health risk assessment.

Microplastics can act as carriers of heavy metals and may enter humans through ingestion and threaten human health. However, the bioaccessibility of heavy metals associated with microplastics and its implications for human health risk assessments are poorly understood. Therefore, in this study, four typical heavy metals (As(V), Cr(VI), Cd(II), and Pb(II)) and one typical microplastic (polyvinyl chloride, PVC) were chosen to estimate the human health risk of microplastic-associated heavy metals by incorporating bioaccessibility. Significant adsorption of heavy metals was observed with the following order for adsorption capacity: Pb(II) > Cr(VI) > Cd(II) > As(V); the efficiencies for desorption of these four heavy metals from PVC microplastics were all below 10%. The Fourier transform infrared spectroscopy results indicated that the functional groups on the surface of the virgin PVC microplastics did not play an important role in the capture process. Heavy metals in both gastric and small intestinal phases were prone to release from PVC microplastics when bioaccessibility was evaluated with the in vitro SBRC (Soluble Bioavailability Research Consortium) digestion model. In addition, Pb(II) bioaccessibility in the gastric phase was significantly higher than those in the other phases, while As(V), Cr(VI), and Cd(II) bioaccessibilities showed the opposite trend. After incorporating bioaccessibility adjustments, the noncarcinogenic hazards and carcinogenic risks determined were lower than those based on total metal contents. The individual hazard quotients (HQ) and carcinogenic risks (CR) for ingestion of these four heavy metals from PVC microplastics were all lower than the threshold values for adults and children. In summary, this study will provide a new view of the human health risks of heavy metals associated with microplastics.

Incorporating bioaccessibility and source apportionment into human health risk assessment of heavy metals in urban dust of Xiamen, China.

Heavy metals in urban dust could pose noticeable human health risks, but there are few studies focusing on comprehensive human health risk assessment with the incorporation of both bioaccessibility and source apportionment in urban dust. Thus, fifty-eight urban dust samples were collected from kindergartens in Xiamen to analyze the bioaccessibility-based, source-specific health risk of heavy metals (V, Co, Ni, As, Mo, Cr, Mn, Cu, Zn, and Pb). Most heavy metals, except for V and Mn, were significantly enriched in urban dust based on their values of geoaccumulation index (Igeo) and may be influenced by human activities. The oral bioaccessibility values of heavy metals, which were estimated by the Solubility/Bioaccessibility Research Consortium (SBRC) in vitro model, ranged from 1.563% to 76.51%. The source apportionment determined by applying the absolute principal component analysis-multiple linear regression (APCS-MLR) model indicated five main potential sources, coal combustion, traffic and industrial, natural, construction and furniture sources, and unidentified sources, with contributions of 34.09%, 20.72%, 18.72%, 7.597% and 18.87%, respectively, to the accumulation of heavy metals in urban dust. After incorporating bioaccessibility adjustments, lower non-carcinogenic and carcinogenic risks of heavy metals were observed than those based on total metal content, with the mean hazard index (HI) values being less than the threshold value (1) and the mean total carcinogenic risk (TCR) values exceeding the precautionary criterion (10-6) for both adults and children. By combining bioaccessibility-based health risk assessment and source apportionment, traffic and industrial emissions and coal combustion dominated the noncarcinogenic and carcinogenic risks induced by heavy metals in urban dust, respectively. This study is expected to promote the systematic integration of source apportionment and bioaccessibility into health risk estimation for heavy metal contamination in urban dust, thus providing useful implications for better human health protection.

Long noncoding RNA ATB promotes ovarian cancer tumorigenesis by mediating histone H3 lysine 27 trimethylation through binding to EZH2.

Ovarian cancer (OC) remains one of the most lethal gynecological malignancies. The unfavourable prognosis is mainly due to the lack of early-stage diagnosis, drug resistance and recurrence. Therefore, it needs to investigate the mechanism of OC tumorigenesis and identify effective biomarkers for the clinical diagnosis. It is reported that long noncoding RNAs (lncRNAs) play important roles during the tumorigenesis of OC. Therefore, the present study aimed to study the role and clinical significance of LncRNAs ATB (lnc-ATB) in the development and progression of OC. In our research, lnc-ATB expression in OC tissues was elevated compared with adjacent normal tissues and high expression of lnc-ATB was associated with poor outcomes of OC patients. The silencing of lnc-ATB blocked cell proliferation, invasion and migration in SKOV3 and A2780 cells. RNA immunoprecipitation and RNA pull-down results showed that lnc-ATB positively regulated the expression of EZH2 via directly interacting with EZH2. Besides, the overexpression of EZH2 partly rescued lnc-ATB silencing-inducing inhibition of cell proliferation, invasion and migration. Chromatin immunoprecipitation assay results demonstrated that the silencing of lnc-ATB reduced the occupancy of caudal-related homeobox protein 1, Forkhead box C1, Large tumour suppressor kinase 2, cadherin-1 and disabled homolog 2 interacting protein promoters on EZH2 and H3K27me3. These data revealed the oncogenic of lnc-ATB and provided a novel biomarker for OC diagnosis. Furthermore, these findings indicated the mechanism of lnc-ATB functioning in the progression of OC, which provided a new target for OC therapy.

Norcantharidin combined with diamminedichloroplatinum inhibits tumor growth and cancerometastasis of hepatic carcinoma in murine.

AIM: Norcantharidin (NCTD) has been used as a clinical antineoplastic drug in China for several years, and diamminedichloroplatinum is a valuable clinical cancer chemotherapy agent. Here, we tried to investigate the effects of NCTD plus diamminedichloroplatinum on hepatic carcinoma in murine. MATERIALS AND METHODS: In vivo and in vitro investigations on anticancer effects of the two drugs were individually made. RESULT: In vitro, the combination of the two drugs resulted in apparent apoptosis and cell proliferation inhibitions of H22 cancer cells. Meanwhile, their coadministration in vivo produced significant suppressions of tumor growth and cancerometastasis. Further, CD31 immunohistochemistry and matrigel tube formation assay demonstrated that angiogenesis was inhibited by NCTD plus diamminedichloroplatinum in vivo and in vitro, respectively. CONCLUSION: Based on the findings, we concluded that NCTD plus diamminedichloroplatinum may have an additive anticancer efficacy because the two drugs work in different ways, and thus, their combination had inhibited cancer cell proliferations and tumor angiogenesis more effectively than either of the compounds alone.

[Effects of glycyrrhizin on the expression of hepatitis B virus and Toll like receptors 2,4 in HepG2.2.15 cells expressing low HBsAg].

OBJECTIVE: To investigate the effects of glycyrrhizin (GL) on the expression of hepatitis B virus e antigen (HBeAg), HBV DNA, Toll-like receptors 2,4 (TLR2,4) and proliferation of cells in HepG2.2.15 cell line. METHODS: Real-time PCR examined HBV DNA, ELISA examined HBsAg, HBeAg and MTT examined the proliferation of cells. FCM examined the positive percent of cells expressing TLR2,4 before and after stimulated with GL, in contrast to the blank group. RESULTS: The expression of HBsAg was low in the cell line, so e antigen was studied. The total HBeAg mean was significantly difference on the second day after stimulated (P<0.01), but only in the group with 400 microg/ml HBeAg decreased significantly in contrast to the blank group (P<0.05), the group with 800 microg/ml increased significantly in contrast to the other groups (P<0.01). The total HBV DNA mean on the third day after stimulated was significant, only the group with 50 microg/ml decreased in contrast to the blank group, but P>0.05, the other four groups increased. The intensity of TLR4 expression in the cells was significantly higher than that of the control group (P<0.05), both of total mean TLR2,4 increased significantly (P<0.01). The four groups except the group with 200 microg/ml increased significantly in no dose-dependent manner (P<0.05). GL in three goups under 200 microg/ml all could make cells proliferate, but only 200 microg/ml group had significant difference compared to the blank group (P<0.05). Both 400 and 800 microg/ml groups inhibited the growth of cells (P<0.01). The proliferation of cells were notably negative correlated with the expression of HBeAg, HBV DNA (P<0.05). CONCLUSION: The study suggestes GL could inhibit or promote HBV DNA replicating and e antigen secreting in mutative HepG2.2.15 cell line, the correlation between the proliferation of cells and the both are negative. GL could upregulate TLR2,4 in no dose-dependent manner. Influencing HBV maybe have no correlation to up regulating TLR2,4 by GL at least in vitro.

Optimization of competitively differentiated polymerase chain reaction in detection of HBV basal core promoter mutation.

AIM: To improve competitively differentiated polymerase chain reaction (CD-PCR) in detection of HBV basal core promoter mutation. METHODS: Recombinant plasmid of double point mutation A1762T/G1764A in basal core promoter of HBV constructed by site-directed mutagenesis was used as mutant control. To reveal the deficiency mechanism of CD-PCR, relationship between the circle number of PCR and the increased speed of products of each competitive primer was comparatively studied. Diversified amount of dNTPs and mutual primer of the competitive primers were tried to optimize CD-PCR. Optimized CD-PCR was evaluated by detecting A1762T/G1764A mutation in recombinant plasmids and clinical sera from patients with HBV infection. RESULTS: The deficiency mechanism of CD-PCR was that the products of mismatched competitive primer grew fast when the amplification of matched primer entered into plateau stage, which led to decrease in or disappearance of the difference in the amount of their products. This phenomenon could be eliminated by reducing dNTPs to 10 micromol/L and mutual primer to about 100 nmol/L. Optimized CD-PCR could detect both mutant and wild strain independent of the amount of templates and the number of PCR cycles. Its detection limit was 10(3) copies/mL, about 50 copies/reaction. About 10% of mutant DNAs among wild type DNAs could be detected. A1762T/G1764A mutant was detected in 41.8% (51/122) of patients with HBV infection, but not detected in controls with negative HBsAg. CONCLUSION: Optimized CD-PCR can detect mutation independent of the amount of initial templates and the number of PCR cycles.

Effects of c-myb antisense RNA on TGF-beta1 and beta1-I collagen expression in cultured hepatic stellate cells.

AIM: To investigate the effects of c-myb antisense RNA on cell proliferation and the expression of c-myb, TGF-beta1 and beta1-I collagen in cultured hepatic stellate cells (HSC) from rats. METHODS: Recombinant retroviral vector of c-myb antisense gene (pDOR-myb) was constructed, and then transfected into retroviral package cell line PA317 by means of DOTAP. The pseudoviruses produced from the resistant PA317 cells were selected with G418 to infect HSCs isolated from rat livers. The cell proliferation was measured by 3-[4, 5-Dimethylthiazolzyl]-2, 5-diphenyl tetrazo-dium bromide(MTT) method. The expression of c-myb, alpha (1)-I collagen and TGF-beta1 mRNA, and c-myb protein in HSCs was detected with semi-quantitive reverse transeription-polymerase chain reaction (RT-PCR) and Western-blot respectively. RESULTS: HSCs from rats were isolated successfully with the viability >98%. In the pDOR-myb infected HSCs, the c-myb protein expression, cell proliferation,and alpha (1)-I collagen and TGF-beta1 mRNA expression were repressed significantly compared with their corresponding control groups (P<0.01). CONCLUSION: c-myb plays a key role in activation and proliferation of HSC. c-myb antisense RNA can inhibit cell proliferation, alpha (1)-I collagen and TGF-beta1 mRNA expression, suggesting that inhibition of c-myb gene expression might be a potential way for the treatment of liver fibrosis.

Novel assay of competitively differentiated polymerase chain reaction for screening point mutation of hepatitis B virus.

AIM: Point mutation, one of the commonest gene mutations, is the most important molecular pathogenesis of cancer and chronic infection. The commonest methods for detection of point mutation are based on polymerase chain reaction (PCR). These techniques, however, cannot be used in large scale screening since they are neither accurate nor simple. For this reason, this study established a novel method of competitively differentiated PCR (CD-PCR) for screening point mutation in clinical practice. METHODS: Two competitively differentiated primers for mutant-type and wild-type templates respectively with an identically complemented region in 3' end except for last 2 base pairs and a different non-complemented region in 5' end were designed. Thus, competitive amplification might be carried out at a lower annealing temperature at first, and then differentiated amplification at a higher annealing temperature when primers could not combine with initial templates. The amplification was performed in one-tube. The products of CD-PCR were detected using microplate hybridization assay. CD-PCR was evaluated by detecting G1896A variant of hepatitis B virus (HBV) in form of recombinant plasmids and in sera from patients with hepatitis B, and compared with allele-specific PCR (AS-PCR) and competitive AS-PCR. RESULTS: CD-PCR was successfully established. It could clearly distinguish wild-type and mutant-type plasmid DNA of G1896A variant when the amount of plasmid DNA was between 10(2)-10(8)copies/reaction, while for AS-PCR and competitive AS-PCR, the DNA amount was between 10(2)-10(4)copies/reaction. CD-PCR could detect one copy of G1896A variant among 10-100 copies of wild-type plasmid DNA. The specificity of CD-PCR was higher than those of AS-PCR and competitive AS-PCR in the detection of HBV G1896A variant in sera from patients with hepatitis B. CD-PCR was independent of the amount of HBV DNA in serum. HBV G1896A variant was more often found in HBeAg (-) patients with a lower level of detectable viremia than that with a higher level of detectable viremia (P=0.0192). CONCLUSION: CD-PCR is more specific since it is less influenced by the amount of initial templates and the cross amplification between mutant- and wild-type amplified products. It is also simple and time-saving. Thus, CD-PCR might be useful in routine gene typing and point mutation screening. HBV G1896A or other more important mutations have to be routinely detected in patients with a detectable level of viremia after HBeAg/antibody conversion in clinical practice.

Codon 249 mutations of p53 gene in non-neoplastic liver tissues.

AIM:To study the significance of p53 gene in hepatocarcinogenesis through analyzing codon 249 mutations of p53 gene in non-neoplastic liver tissues.METHODS:Codon 249 mutation was detected using single-stranded conformational polymorphism analysis and allele-specific PCR in liver tissues from 10 cases of chronic hepatitis, 5 cases of cirrhosis and 20 cases of HCCs.RESULTS:The detection rate of codon 249 mutation in chronic hepatitis, cirrhosis and pericancerous tissues was 70% (7/10), 100% (5/5) and 70% (14/20), respectively by AS-PCR. These mutations could not be detected by SSCP analysis. The detection rates were 65% (13/20) and 45% (9/20) in cancerous tissues by AS-PCR and SSCP analysis.CONCLUSION:Codon 249 mutations of p53 gene were very popular in non-neoplastic liver tissues though the number of those mutant cells was only in subsection. Those mutations in cancerous tissues might take place in the stage before the formation of tumor.