[Characteristics, Ecological Risk Assessment, and Source Apportionment of Soil Heavy Metals in the Yellow River Floodplain of Yinchuan City].

In order to study the status and sources of heavy metal pollution in Yinchuan Yellow River floodplain soils, we used inductively coupled plasma mass spectrometry (ICP-MS) to determine the presence of eight heavy metals in 92 soil samples from the Yinchuan Yellow River floodplain and used enrichment factors, geological accumulation index, and potential ecological risk index to analyze and evaluate the characteristics of heavy metal pollution in the study area. Combined correlation analysis, absolute factor analysis-multiple linear regression model (APCS-MLR), positive matrix factorization (PMF), and geostatistics were used to analyze the sources of soil heavy metals. The results showed that the content of eight heavy metals in the surface soil of the Yellow River floodplain in Yinchuan City were lower than the screening value of soil pollution risk in agricultural land; Cu and Pb contents were lower than the background value of Yinchuan City soil, and the contents of the remaining six elements were higher than the background value. The coefficients of variation of Zn and Cd were large and in the medium variation level and were influenced by anthropogenic activities. The heavy metal content varied between different land types and generally showed that wasteland > abandoned farmland > woodland > cultivated land. The average content of Cu and Pb in forest and arable soils was lower than the regional background value, whereas the rest of the heavy metals in different land types were higher than the soil background value. The analysis of enrichment factors showed that Zn and Cd were slightly enriched in the study area, and the cumulative index method and the evaluation of the potential risk of single heavy metals indicated that more than 60% of the sites in the study area were contaminated with Cd at a medium or higher potential ecological hazard. The comprehensive evaluation results of potential ecological risk showed that the overall ecological risk level of the study area was mild. From the distribution of heavy metal ecological risk comprehensive index sample points, only one point was in moderate ecological hazard, and the pollution point showed very few. Comprehensive correlation analysis, APCS-MLR model, PMF model, and geostatistical analysis results confirmed that Zn and Cd in the study area were mainly derived from human activities such as agricultural activities and transportation, and the remaining heavy metals were derived from soil parent materials. The results of this study can provide a scientific basis for the ecological protection and sustainable development of the Yellow River in Yinchuan City.

Analysis of subcellular structural tension in axonal growth of neurons.

The growth and regeneration of axons are the core processes of nervous system development and functional recovery. They are also related to certain physiological and pathological conditions. For decades, it has been the consensus that a new axon is formed by adding new material at the growth cone. However, using the existing technology, we have studied the structural tension of the nerve cell, which led us to hypothesize that some subcellular structural tensions contribute synergistically to axonal growth and regeneration. In this review, we classified the subcellular structural tension, osmotic pressure, microfilament and microtubule-dependent tension involved controllably in promoting axonal growth. A squeezing model was built to analyze the mechanical mechanism underlying axonal elongation, which may provide a new view of axonal growth and inspire further research.

Norcantharidin enhances bortezomib-antimyeloma activity in multiple myeloma cells in vitro and in nude mouse xenografts.

Norcantharidin (NCTD), the demethylated analog of the Chinese medicine cantharidin, exhibits anti-myeloma activity by inactivating nuclear factor-κB (NF-κB), which is implicated in multiple myeloma (MM) cell survival and resistance to bortezomib (BTZ). We investigated whether NCTD could potentiate the anti-tumor activity of BTZ in MM. NCTD inhibited the proliferation of MM cells and potentiated the anti-myeloma effects of BTZ by down-regulating IKKα and p-IκBα, which induced the accumulation of IκBα and inhibited the constitutive activation of NF-κB. This effect was correlated with the suppression of NF-κB-regulated gene products. Furthermore, a chemotherapy-potentiating effect of NCTD on BTZ was also observed in vivo. Our study demonstrated that NCTD and BTZ exhibit significant therapeutic effects on MM through the NF-κB signal pathway in vitro and in vivo. Future studies will investigate the combined effects of NCTD and BTZ in patients with MM.

[Norcantharidin potentialize the chemosensitivity of adriamycin through the NF-κB/IκBα signaling pathway].

OBJECTIVE: To explore the synergetic effect of norcantharidin (NCTD) and adriamycin (ADR) on the proliferation and apoptosis of multiple myeloma (MM) cells. METHODS: Human MM cell line U266 cells were treated with NCTD alone (10 µmol/L) or in combination with ADR (0.25 µmol/L). MTT and Annexin V/PI staining were used to determine cell viability and apoptosis. The protein expression of nuclear factor-κB P65 (NF-κB P65), phosphorylated NF-κB p65 (p-NF-κB p65), NF-κB P65 inhibitor IκBα, phosphorylated IκBα (p-IκBα), survivin, Bcl-2 and Bax were determined by Western blot. Immunohistochemistry was used to determine the expression of vascular endothelial growth factor (VEGF). RESULTS: (1) NCTD potentiated the cytotoxicity and pro-apoptotic effects induced by ADR. The combination of NCTD and ADR had synergistic anti-proliferation effect. (2) Combination of ADR and NCTD downregulated the expression of nuclear NF-κB P65 and cytoplasm p-IκBα induced by ADR. The expression of nuclear NF-κB P65 and cytoplasm p-IκBα decreased from 2.08 ± 0.29 and 0.39 ± 0.07 to 0.48 ± 0.08 and 0.02 ± 0.01 respectively, while the expression of the cytoplasm NF-κB P65 and IκBα were unchanged in the ADR alone group and the combined group. (3) The expression of survivin and bcl-2 decreased from 0.31 ± 0.05 and 0.23 ± 0.05 to 0.03 ± 0.02 and 0.05 ± 0.02, while the expression of Bax increased from 0.46 ± 0.06 to 0.62 ± 0.08 respectively in ADR alone group and combined group. (4) The positive rate of VEGF in ADR group and combination group were (44.6 ± 4.4)% and (27.0 ± 2.1)% respectively, indicating that NCTD could potentiate the inhibition effect on VEGF induced by ADR. CONCLUSIONS: The results suggest that NCTD can potentialize the chemosensitivity of multiple myeloma cells to ADR through regulating NF-κB/IκBα signaling pathway and NF-κB-regulated gene products including survivin, Bcl-2, Bax and VEGF.