How does air pollution affect urban settlement of the floating population in China? New evidence from a push-pull migration analysis.

BACKGROUND: Severe air pollution in China threatens human health, and its negative impact decreases the urban settlement intentions of migrants in destination cities. We establish a comprehensive framework based on the push-pull migration model to investigate this phenomenon. METHODS: We employ a logistic model to analyze air pollution's impact on the settlement intentions of the floating population based on the CMDS 2017 in China, combining the city-level socioeconomic variables with the individual-level variables. RESULTS: Our results show that the annual average concentration of PM2.5 increases by 1 unit and that the probability of migrants' settlement intentions will decrease by 8.7%. Using a heterogeneity analysis, we find that the following migrant groups are more sensitive to air pollution: males, people over 30 years old, less educated people, and migrants with nonagricultural hukou. With every 1 unit increase in PM2.5, each group's settlement intentions decrease by 13.2, 16.7, 16.9, and 12.6%, respectively. CONCLUSIONS: Our results are consistent with existing studies. This study discovers that both external environment and internal factors influence migrants' settlement intentions. Specifically, the differences in population sizes, economic development levels, public services, infrastructure conditions, and environmental regulations between cities play a significant role in migration decisions. We also confirm heterogeneous sensitivities to air pollution of different migrant subgroups in terms of individual characteristics, family factors, migration features, social and economic attributes.

Downregulation of ATP-binding cassette subfamily C member 4 increases sensitivity to neoadjuvant radiotherapy for locally advanced rectal carcinoma.

OBJECTIVE: This study was designed to verify the effect of ATP-binding cassette subfamily C member 4 on radiosensitivity of locally advanced rectal carcinoma. SETTING: The expression of ATP-binding cassette subfamily C member 4 protein in 121 pretreatment tissue samples from locally advanced rectal carcinoma patients was detected by immunohistochemistry. DESIGN: Pathological response to radiotherapy was evaluated according to tumor regression grading by postoperative histological examinations after they received long-course preoperative neoadjuvant radiotherapy, and the association between clinicopathological data and tumor regression grading was analyzed retrospectively. For further validation, short hairpin RNA was constructed and transfected into colorectal carcinoma cell line HT29. The knockdown efficiency was confirmed at both RNA and protein levels. The altered radiosensitivity was evaluated by methylthiazolyl tetrazolium assay, colony formation assay, flow cytometry, and Hoechst 33258 staining. RESULTS: Univariate analysis revealed that ATP-binding cassette subfamily C member 4 expression (p < 0.001), P53 type (p = 0.069), and CEA (p = 0.100) were possibly associated with tumor regression grading, and multivariate analysis demonstrated that ATP-binding cassette subfamily C member 4 expression (p < 0.001) and P53 type (p = 0.039) were positively correlated with response to neoadjuvant radiotherapy in locally advanced rectal carcinoma patients. Lentiviral vector was successfully introduced into HT29 cells and inhibited ATP-binding cassette subfamily C member 4 expression efficiently and persistently. Downregulation of ATP-binding cassette subfamily C member 4 expression significantly enhanced inhibition of cell proliferation, decreased colony formation capacity, and increased cell apoptosis induced by irradiation, as examined by a series of experiments in vitro. In addition, radiobiological parameters calculated according to the single-hit multitarget model were also decreased significantly. CONCLUSIONS: Our data indicate that ATP-binding cassette subfamily C member 4 may be a useful molecular marker in predicting radiosensitivity, and a potential target in improving the response to neoadjuvant radiotherapy in locally advanced rectal carcinoma patients.

Understanding the Geography of COVID-19 Case Fatality Rates in China: A Spatial Autoregressive Probit-Log Linear Hurdle Analysis.

This study employs a spatial autoregressive probit-log linear (SAP-Log) hurdle model to investigate the influencing factors on the probability of death and case fatality rate (CFR) of coronavirus disease 2019 (COVID-19) at the city level in China. The results demonstrate that the probability of death from COVID-19 and the CFR level are 2 different processes with different determinants. The number of confirmed cases and the number of doctors are closely associated with the death probability and CFR, and there exist differences in the CFR and its determinants between cities within Hubei Province and outside Hubei Province. The spatial probit model also presents positive spatial autocorrelation in death probabilities. It is worth noting that the medical resource sharing among cities and enjoyment of free medical treatment services of citizens makes China different from other countries. This study contributes to the growing literature on determinants of CFR with COVID-19 and has significant practical implications.

[Sources, Characteristics and Transformation Dynamics of Fluorescent Dissolved Organic Matter in the Silin Reservoir].

The aim of this study was to examine the sources and characteristics of various fluorescent dissolved organic matter (FDOM) components as well as their transformation dynamics. FDOM was determined in the incoming, surface (0 m), deeper (20 m), and outflowing waters of the Silin Reservoir in winter (January), spring (April), summer (June), and autumn (October) using excitation-emission matrix (EEM) spectra coupled with parallel factor (PARAFAC), EEM-PARAFAC modelling. The EEM-PARAFAC modelling results demonstrated that dissolved organic matter (DOM) in the Silin Reservoir waters was composed of three fluorescent components. These included terrestrial humic-like substances (C type) of terrestrial origin (component 1), microbial humic-like substances (M type) of phytoplankton origin (component 2), and protein-like or tryptophan-like or tyrosine-like (component 3) of phytoplankton origin. In addition, the terrestrial humic-like substances (C type) was identified from two fluorescence peaks (peak C at Ex/Em=305-355/414-458 nm and peak A at Ex/Em 245-270/414-458 nm) while the microbial humic-like substances (M type) was identified from peaks that included peak M at Ex/Em 280-305/380-398 nm and peak A 230-235/380-417 nm. Similarly, protein-like or tryptophan-like or tyrosine-like components were also detected from two fluorescence peaks, including peak T 270-285/316-354 nm and peak Tuv 225-230/316-354 nm. The fluorescence intensity of terrestrial humic-like substances gradually decreased in incoming waters to surface (0 m), deeper (20 m), and subsequently, in outflowing waters. This indicates the gradual degradation of the humic-like substances and their recalcitrant nature during water transport during the incoming-surface-deeper-outflowing water cycle in both summer and winter seasons by numerous environmental factors. These included photochemical, microbial, and dam barrier-affected physical processes. Conversely, from the fluorescence intensity results of microbial humic-like substances (M type), production or partial (in some cases complete) degradation in surface-deeper-outflowing waters, fluctuated. This suggests that microbial humic-like substances are autochthonously produced from phytoplankton, but are highly labile in response to photochemical, microbial, and dam barrier-affected physical processes. From the fluorescence intensity results of protein-like or tryptophan-like or tyrosine-like substances, it demonstrated that they were newly produced in surface (0 m) waters in the summer season, but in the winter season they were significantly produced in both surface and deeper waters of the reservoir, and then decreased in the outflowing waters. This suggests that protein-like or tryptophan-like or tyrosine-like substances are autochthonously produced by phytoplankton that simultaneously reproduced and then were degraded in surface and deeper waters by photochemical, microbial, and dam barrier-affected physical processes. These results therefore imply that the FDOM components identified by EEM-PARAFAC modelling are crucial to better understand the source characteristics of bulk DOM, its transformation mechanisms, and its the dynamics in a reservoir water system.

Knockdown of ZFX inhibits gastric cancer cell growth in vitro and in vivo via downregulating the ERK-MAPK pathway.

Zinc finger protein X-linked (ZFX) is a zinc finger transcription factor encoded on the X chromosome. Here, we found that ZFX expression was significantly upregulated in gastric cancer (GC) cell lines and tissues. Knockdown of ZFX induced significant apoptosis and cell cycle arrest in SGC7901 and MGC803 cells. Moreover, we demonstrated for the first time that knockdown of ZFX inhibited gastric cancer cell growth in vitro and in vivo via downregulating the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK-MAPK) pathway. Therefore, ZFX play a prominent role in GC tumorigenicity and may have potential applications in the diagnosis or treatment of GC.

[Competing endogenous RNA regulation mechanism and its role in the development and progression of colorectal cancer].

MicroRNAs are negative regulators of mRNA, and latest studies show that "mRNAs can also inhibit microRNAs". With these reciprocal interactions, different mRNAs with identical "microRNA binding site" cim regulate each other by competitively binding to the same microRNA pool. This is the novel competing endogenous RNA (ceRN A)regulating mechanism. The ceRN A mechanism, which is a totally new regulating mechanism , greatly expands the regulatory network across genes. It has been proved by experimental evidence that, in HCT116 colon cancer cells,KRAS and PTEN , ZEB2 and PTEN can regulate each other by ceRNA mechanism.

[Long non-coding RNA influences radiosensitivity of colorectal carcinoma cell lines by regulating cyclin D1 expression].

OBJECTIVE: To screen long non-coding RNA which influences radiosensitivity of colorectal carcinoma cell lines and investigate the mechanism. METHODS: Under different doses of radiation, colony formation assay and single-hit multi-target model were conducted to draw dose-survival curve and SF2 value of colorectal carcinoma cell lines(RKO, Lovo) was calculated. High-throughput lncRNA/mRNA chips were used to screen lncRNA genes and protein coding genes with expression differences more than 2 folds between RKO, Lovo cell lines and RKO cell line receiving 2Gy radiation. The main action pathway was computed by Gene Ontology analysis combined with Pathway analysis in order to explore the mechanism which induces the effect of lncRNA on radiosensitivity of colorectal carcinoma cell lines. Further experiment on P53, P21, cyclin D1 expression contents of RKO cell line was confirmed by real-time RT-PCR. RESULTS: Lovo(SF2=0.47) was more sensitivity to radiation than RKO(SF2=0.53) according to the outcome of colony formation assay. High-throughput lncRNA/mRNA chips identified a total of 268 lncRNA genes and 270 protein coding genes. Gene Ontology analysis showed that the expression of genes associated with cell cycle process were significantly different (38.6%). There was a significant relationship between expression of several lncRNAs and CCND1 gene. Real-time RT-PCR showed no significant differences of P53 and P21 expression in RKO and Lovo cell lines(P>0.05), while cyclin D1 expression of RKO cell line was higher than that of Lovo cell lines(P<0.05). After exposed to 2 Gy doses of radiation, there was an obvious decrease of cyclin D1 expression in RKO cell lines(P<0.05), while P53 and P21 expressions were not different(P>0.05). CONCLUSION: The possible mechanism is that lncRNAs compose transcription compound to combine with CCND1 gene and influence radiosensitivity of colorectal carcinoma cell lines by regulating expression of cyclin D1, which is independent of P53-P21-cyclin D1 pathway.

[Down regulation of multidrug resistance-associated protein 4 expression by RNA interference enhances radiosensitivity of colorectal carcinoma cell lines in vitro].

OBJECTIVE: To investigate the effect of multidrug resistance-associated protein 4 (MRP4) expression on the radiosensitivity of colorectal carcinoma cell lines in vitro. METHODS: The vector of shRNA for RNA interference was constructed and then transfected into HCT116 cell line to steadily down-regulate the expression of MRP4. HCT116 cells were divided into 3 groups including the CON group(non-transfected), NC group (negative control virus was added), and KD group (RNAi target was added for transfection). To test the effectiveness of RNA interference, real-time polymerase chain reaction and Western blot were used to measure the expression pattern of MRP4 at both mRNA and protein levels, respectively. For the examination of the effect of RNA interference of MRP4 on the radiosensitivity, flow cytometry was used to calculate the rate of apoptotic cells 24 h after 4 Gy radiation. Proliferation of the cells was measured via MTT assay at different time points. RESULTS: ShRNA plasmid was successfully constructed. Transfection of this constructed vector into HCT116 cell line caused steady silencing of MRP4 expression (HCT116-KD). MRP4 mRNA and protein expression were significantly down-regulated following RNA interference(P<0.05). Twenty-four hours after radiation, the apoptosis rate of KD cell line was (71.7±0.8)%, significantly higher than that in the CON group [(56.1±0.9)%] and NC group[(59.8±0.8)%](P<0.05). Fourty-eight hours and 72 hours after radiation, the proliferation was significantly inhibited in KD cells compared to the control groups(P<0.05). CONCLUSIONS: Expression of MRP4 is closely related to radio-tolerance of colorectal carcinoma. Down-regulation of MRP4 expression by RNA interference enhances radiosensitivity of colorectal carcinoma cell lines in vitro. MRP4 may be an effective molecular marker for predicting the radiosensitivity of colorectal carcinoma.