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1.
Front Vet Sci ; 10: 1293314, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38046570

RESUMO

The objective of this experiment was to determine the effect of low crude protein (CP) diets containing increasing amounts of enzymolytic soybean meal (ESBM) on growth performance, economic benefit and organ development and the role of cecal fermentation and microbiota in broilers. A total of 360 one-day-old Arbor Acres chicks were randomly allocated into 6 groups with 6 replicates and 10 chicks each. The six dietary treatments consisted of a standard high-CP diet (PC), a low-CP diet (NC), and an NC diet with 0.5, 1.0, 1.5%, or 2.0% ESBM. The experiment lasted for 42 days. Compared to PC, NC showed decreased (p < 0.05) average daily gain (ADG) in broilers from 22 to 42 days and from 1 to 42 days, while increasing levels of ESBM quadratically increased (p < 0.05) ADG from 1 to 42 days. Feed cost and total revenue in the NC were lower (p < 0.05) than that in the PC, while supplementation with ESBM in the NC linearly increased (p < 0.05) net profit and economic efficiency in broilers. There were significant differences (p < 0.05) in the liver, proventriculus and gizzard indices between the PC and NC groups, and supplementation with ESBM linearly increased (p < 0.05) the relative weights of liver, pancreas, proventriculus and gizzard in broilers at 42 days of age. The PC group had a higher cecal acetic acid concentration at 21 days and propionic acid concentration at both 21 and 42 days than the NC group (p < 0.05). Cecal acetic acid and propionic acid concentrations linearly increased (p < 0.05) with increasing levels of ESBM in broilers at 42 days of age. No significant differences in ACE, Chao1, Shannon and Simpson indices were observed among groups (p > 0.05), while the cecal abundances of Bacteroides, Faecalibacterium and Clostridium IV increased (p < 0.05) with the increasing level of ESBM in the low-CP diets. In conclusion, feeding ESBM improved economic efficiency, digestive organ development, cecal fermentation and microbial community composition, and up to 2.0% ESBM addition had no negative effect on the growth performance in broilers fed low CP diets.

2.
Pathol Res Pract ; 252: 154919, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37939428

RESUMO

BACKGROUND: Previous related studies have found that the levels of tumor-associated macrophages (TAMs) were correlated with prognoses in hepatocellular carcinoma. However, the prognostic value of TAMs for East Asian HCC patients remains inconclusive. METHODS: Our objectives were to systematically review the performance and explore the prognostic and clinical value of TAMs in patients with HCC. A total of 23 relevant studies of 4389 patients were included into our meta-analysis. And the work has been reported in line with PRISMA guidelines. RESULTS: The results demonstrated that increased expression level of peritumoral infiltrated CD68+ macrophages had a poor prognostic value on overall survival (OS), disease free survival (DFS) and recurrence-free survival (RFS). However, there was no correlation between disease-free survival (DFS) and the abundance of CD68+ TAMs both in intratumoral regions. Additionally, low density of CD169+, high density of CD206, and high density of CD204+ TAMs had a worse prognostic value on OS while the CD163+ TAMs had no diagnostic value on OS. The densities of CD68+ TAMs exhibited significantly correlation with AFP level and vascular invasion. The levels of CD169+ TAMs showed apparent relation to vascular invasion and TNM stages. CONCLUSION: These findings indicate that TAMs may accomplish as significant prognostic biomarkers for East Asian HCC patients. However, further researches should be performed to estimate the clinical value of TAMs in HCC.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Humanos , Carcinoma Hepatocelular/patologia , Macrófagos Associados a Tumor/patologia , População do Leste Asiático , Neoplasias Hepáticas/patologia , Prognóstico
3.
Diagnostics (Basel) ; 13(17)2023 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-37685308

RESUMO

Suppressor of mother against decapentaplegic (SMAD) family proteins are central to one of the most versatile cytokine signalling pathways in metazoan biology, the transforming growth factor-ß (TGF-ß) pathway. The TGF-ß pathway is widely known for its dual role in cancer progression as both an inhibitor of tumour cell growth and an inducer of tumour metastasis. This is mainly mediated through SMAD proteins and their cofactors or regulators. SMAD proteins act as transcription factors, regulating the transcription of a wide range of genes, and their rich post-translational modifications are influenced by a variety of regulators and cofactors. The complex role, mechanisms, and important functions of SMAD proteins in tumours are the hot topics in current oncology research. In this paper, we summarize the recent progress on the effects and mechanisms of SMAD proteins on tumour development, diagnosis, treatment and prognosis, and provide clues for subsequent research on SMAD proteins in tumours.

4.
Adv Sci (Weinh) ; 10(17): e2207080, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37096833

RESUMO

Bone is the second leading metastatic site for hepatocellular carcinoma (HCC). Patients with HCC and bone metastasis suffer poor quality of life and reduced survival time. Extracellular vesicles (EVs) are widely involved in HCC formation and metastasis. However, the communication between primary HCC and bone lesions mediated by EVs remains unclear and the possible effect of bone metastasis on the progression of HCC remains largely unknown. Here, bone-metastasized HCC-derived EVs (BM-EVs) are found to localize to orthotropic HCC cells and promote HCC progression. Mechanistically, miR-3190-5p (miR-3190) is upregulated in intracellular HCC cells isolated from bone lesions as well as in their derived EVs. miR-3190 in BM-EVs is transferred into orthotopic tumor cells and enhances their metastatic capacity by downregulating AlkB homolog 5 (ALKBH5) expression. Decreased level of ALKBH5 exacerbates the prometastatic characteristics of HCC by modulating gene expression in N6-methyladenosine-dependent and -independent ways. Finally, antagomir-miR-3190-loaded liposomes with HCC affinity successfully suppress HCC progression in mice treated with BM-EVs. These findings reveal that BM-EVs initiate prometastatic cascades in orthotopic HCC by transferring ALKBH5-targeting miR-3190 and miR-3190 is serving as a promising therapeutic target for inhibiting the progression of HCC in patients with bone metastasis.


Assuntos
Neoplasias Ósseas , Carcinoma Hepatocelular , Vesículas Extracelulares , Neoplasias Hepáticas , MicroRNAs , Animais , Camundongos , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , MicroRNAs/genética , MicroRNAs/metabolismo , Qualidade de Vida , Vesículas Extracelulares/metabolismo , Linhagem Celular Tumoral , Neoplasias Ósseas/genética , Neoplasias Ósseas/metabolismo
5.
BMC Cancer ; 22(1): 1166, 2022 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-36368958

RESUMO

BACKGROUND: Intrahepatic cholangiocarcinoma (ICC), originating from the bile ducts, is the second most common primary liver malignancy, and its incidence has recently increased. H2A.Z, a highly conserved H2A variant, is emerging as a key regulatory molecule in cancer. However, its underlying mechanism of action in ICC cells remains unclear.  METHODS: Here, we examined the expression of H2A.Z and SFRP1 in normal intrahepatic cholangiocytes, ICC cell lines, ICC tissue microarrays, and fresh specimens. The correlations between H2A.Z or SFRP1 expression and clinical features were analysed. The overall survival rate was analysed based on H2A.Z and SFRP1 expression. Immunoprecipitation was used to analyse the recruitment of KDM1A, and ChIP sequencing and BSP were used to analyse the enrichment of methylation-related molecules such as H3K4me1 and H3K4me2 in the SFRP1 promoter and reveal the underlying mechanisms. Knockdown and rescue experiments were used to determine the potential mechanism by which H2A.Z and SFRP1 promote tumorigenesis in vitro. RESULTS: We showed that upregulation of H2A.Z expression is linked to downregulation of SFRP1 expression in ICC tissues and poor overall survival in patients with ICC. H2A.Z interacted with KDM1A in the nucleus to bind to the -151 ~ -136 bp region upstream of the SFRP1 promoter to increase its demethylation in ICC cells. Functionally, H2A.Z silencing inhibited the proliferation and invasion of ICC cells, and these effects were mitigated by SFRP1 silencing in ICC cells. CONCLUSIONS: Our findings reveal that H2A.Z inhibits SFRP1 expression through chromatin modification in the context of ICC by forming a complex with KDM1A in the nucleus.


Assuntos
Neoplasias dos Ductos Biliares , Colangiocarcinoma , Humanos , Metilação , Colangiocarcinoma/patologia , Histonas/metabolismo , Carcinogênese/metabolismo , Transformação Celular Neoplásica/metabolismo , Neoplasias dos Ductos Biliares/patologia , Ductos Biliares Intra-Hepáticos/patologia , Linhagem Celular Tumoral , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/genética , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Histona Desmetilases/genética , Histona Desmetilases/metabolismo
6.
Int J Oncol ; 60(1)2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34878151

RESUMO

Subsequently to the publication of the above article, and a Corrigendum that has already been published with the intention of showing the corrected version of Fig. 5 (DOI: 10.3892/ijo.2021.5213; published online on May 5, 2021), the authors have realized that only the data for Fig. 5C needed to be corrected with respect to the original figure published in the article, and there was no need to have presented replacement data for Fig. 5E in the previous Corrigendum. The further revised version of Fig. 5, featuring the corrected data for Fig. 5C, is shown on the next page. All the authors agree to this Corrigendum. Note that the revisions made to this figure do not adversely affect the results reported in the paper, or the conclusions stated therein. The authors regret that Fig. 5 was not presented in its finally revised form in the previous Corrigendum, and offer their apologies to the Editor and to the readers of the Journal. [the original article was published in International Journal of Oncology 54: 479­490, 2019; DOI: 10.3892/ijo.2018.4659].

7.
Front Mol Biosci ; 8: 670241, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34095224

RESUMO

Hepatocellular carcinoma (HCC) has been recognized as the third leading cause of cancer-related deaths worldwide. There is increasing evidence that the abnormal expression of autophagy-related genes plays an important role in the occurrence and development of HCC. Therefore, the study of autophagy-related genes can further elucidate the genetic drivers of cancer and provide valuable therapeutic targets for clinical treatment. In this study, we used 232 autophagy-related genes extracted from the Human Autophagy Database (HADb) and Molecular Signatures Database (MSigDB) to construct 1884 autophagy-related gene pairs. On this basis, we developed a prognostic model based on autophagy-related gene pairs using least absolute shrinkage and selection operator (LASSO) Cox regression to evaluate the prognosis of patients after liver cancer resection. We then used 845 liver cancer samples from three different databases to test the reliability of the risk signature through survival analysis, receiver operating characteristic (ROC) curve analysis, univariate and multivariate analysis. To further explore the underlying biological mechanisms, we conducted an enrichment analysis of autophagy-related genes. Finally, we combined the signature with independent prognostic factors to construct a nomogram. Based on the autophagy-related gene pair (ARGP) signature, we can divide patients into high- or low-risk groups. Survival analysis and ROC curve analysis verified the validity of the signature (AUC: 0.786-0.828). Multivariate Cox regression showed that the risk score can be used as an independent predictor of the clinical outcomes of liver cancer patients. Notably, this model has a more accurate predictive effect than most prognostic models for hepatocellular carcinoma. Moreover, our model is a powerful supplement to the HCC staging indicator, and a nomogram comprising both indicators can provide a better prognostic effect. Based on pairs of multiple autophagy-related genes, we proposed a prognostic model for predicting the overall survival rate of HCC patients after surgery, which is a promising prognostic indicator. This study confirms the importance of autophagy in the occurrence and development of HCC, and also provides potential biomarkers for targeted treatments.

8.
Int J Oncol ; 58(6)2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33955524

RESUMO

Subsequently to the publication of the above article, the author realized that Fig. 5 on p. 486 contained some errors on account of the figure having been compiled incorrectly; essentially, the published version of the figure contained incorrect images for the panels presented in Fig. 5C and E. The authors were able to re­examine their original data, and identify the data that was intended to have been shown for these figure parts. The corrected version of Fig. 5 is shown on the next page, featuring the correct data for Fig. 5C and E, including new bar charts showing the quantification of these data. The authors confirm that these data continue to support the main conclusions presented in their paper, and are grateful to the Editor of International Journal of Oncology for allowing them this opportunity to publish a Corrigendum. They also apologize to the readership for any inconvenience caused. [the original article was published in International Journal of Oncology 54: 479­490, 2019; DOI: 10.3892/ijo.2018.4659].

9.
Front Oncol ; 10: 565266, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33344226

RESUMO

MicroRNAs (miRNAs) have been reported to play critical roles in the pathological development of hepatocellular carcinoma (HCC), one of the most common cancers in the world. Our study aims to explore the expression, function and mechanism of miR-631 in HCC. Our findings are that expression of miR-631 is significantly down-regulated in HCC tissue compared with that in adjacent non-cancerous tissue, and low expression of miR-631 in HCC tissue is associated with cirrhosis, multiple tumors, incomplete tumor encapsulation, poor tumor differentiation, and high TNM stage. Our test results showed that miR-631 could inhibit migration, invasion, epithelial-mesenchymal transition (EMT) and intrahepatic metastasis of HCC. Receptor-type protein tyrosine phosphatase epsilon (PTPRE) as a downstream target of miR-631 could promote migration, invasion and EMT of HCC cells. Besides, the expression of PTPRE had a negative correlation with the expression of miR-631 both in vivo and in vitro, and increasing expression of PTPRE could reverse inhibitory effects of miR-631 in HCC cells. In sum, our study first demonstrated that miR-631 targeted PTPRE to inhibit intrahepatic metastasis in HCC. We gain insights from these findings into the mechanism of miRNAs regulation in HCC metastasis and further introduce a novel therapeutic target for HCC treatment.

10.
Neural Netw ; 125: 165-173, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32097831

RESUMO

This paper discusses the reachable set estimation problem of neural networks with mixed delays. Firstly, by means of the maximal Lyapunov-Krasovskii functional, we obtain a non-ellipsoid form of the reachable set. Further more, when calculating the derivative of the maximum Lyapunov functional, the lower bound lemma and reciprocally convex approach method are used to solve the reciprocally convex combination term, which reduce the related decision variables. Secondly, we extend the results to polytopic uncertainties neural networks and consider the case of uncertain differentiable parameters. Finally, two numerical examples and one application example are listed to show the validity of our methods.


Assuntos
Simulação por Computador , Redes Neurais de Computação , Incerteza , Simulação por Computador/tendências , Humanos , Fatores de Tempo
11.
Front Oncol ; 10: 617837, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33520726

RESUMO

Exosomes are small membranous vesicles released by many kinds of cells, and are indispensable in cell-to-cell communication by delivering functional biological components both locally and systemically. Long non-coding RNAs (lncRNAs) are long transcripts over 200 nucleotides that exhibit no or limited protein-coding potentials. LncRNAs are dramatic gene expression regulators, and can be selectively sorted into exosomes. Exosomal lncRNAs derived from cancer cells and stromal cells can mediate the generation of pre-metastatic niches (PMNs) and thus promote the progression of cancer. In this review, we summarized the fundamental biology and characteristics of exosomal lncRNAs. Besides, we provided an overview of current research on functions of exosomal lncRNAs between cancer cells and non-cancer cells. A deep understanding of exosomal lncRNAs' role in cancer will be facilitated to find important implications for cancer development and treatment.

12.
J Exp Clin Cancer Res ; 38(1): 413, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31590696

RESUMO

BACKGROUND: CyclinD1 is crucial for cell cycling and can regulate the expression of Dicer, a crucial regulator of microRNA maturation. However, little is known on how CyclinD1 regulates Dicer and miRNA expression, and the progression of intrahepatic cholangiocarcinoma (ICC). METHODS: The expression of CyclinD1 and Dicer in non-tumor cholangiocytes, ICC cells and tissues as well as their association with clinicopathological characteristics and survival were examined. The potential mechanisms by which CyclinD1 regulates Dicer and relative miRNA expression were determined by immunoprecipitation, ChIP sequence, BSP and luciferase reporter assays following induction of CyclinD1 over-expression or silencing and Dicer silencing. The impact of CyclinD1 and/or Dicer silencing on the growth of ICC was tested in vivo. RESULTS: Up-regulated CyclinD1 was associated with down-regulated Dicer expression in ICC tissues and poorer overall survival in patients with ICC. CyclinD1 interacted with the nuclear H3K9me3 and SUV39H1 and bound to the Dicer promoter to increase its CpG island methylation in ICC cells. Functionally, CyclinD1 silencing inhibited the malignancy of ICC cells, which were mitigated partially by Dicer silencing in ICC cells. Dicer silencing down-regulated miR-1914-5p and miR-541-5p expression, which targeted and promoted CyclinD1 and CDK6 expression in ICC cells. CONCLUSIONS: Our findings uncover that CyclinD1 inhibits Dicer expression by chromatin modification to reduce miR-1914-5p/miR-541-5p expression, which positively-feedback enhances CyclinD1 and CDK6 expression and progression of ICC.


Assuntos
Neoplasias dos Ductos Biliares/patologia , Colangiocarcinoma/patologia , Cromatina/genética , Ciclina D1/metabolismo , RNA Helicases DEAD-box/metabolismo , Regulação Neoplásica da Expressão Gênica , MicroRNAs/metabolismo , Ribonuclease III/metabolismo , Animais , Neoplasias dos Ductos Biliares/genética , Neoplasias dos Ductos Biliares/metabolismo , Colangiocarcinoma/genética , Colangiocarcinoma/metabolismo , Cromatina/metabolismo , Ciclina D1/genética , RNA Helicases DEAD-box/genética , Progressão da Doença , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , MicroRNAs/genética , Pessoa de Meia-Idade , Invasividade Neoplásica , Prognóstico , Ribonuclease III/genética , Taxa de Sobrevida , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de Xenoenxerto
13.
Int J Oncol ; 54(2): 479-490, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30570110

RESUMO

Polo­like kinase 4 (PLK4) has been identified as an oncogene, which is overexpressed in various types of human cancer; however, its role in colorectal cancer (CRC) development remains unknown. The present study demonstrated that PLK4 protein expression was upregulated in CRC tissues compared with in normal tissues through western blotting. In addition, immunohistochemical analysis of 39 CRC specimens further demonstrated that PLK4 protein expression was upregulated in 64.1% (25/39) of samples. Increased PLK4 expression was closely associated with enhanced tumor size (P=0.031), lymph node metastasis (P=0.016) and TNM stage (P=0.001). Subsequently, cell viability, wound scratch, migration and invasion assays were conducted in vitro, and nude mice CRC xenograft models were generated. The results demonstrated that knockdown of PLK4 in CRC cells resulted in significant decreases in cell viability and proliferation, and decreased the protein expression levels of N­cadherin and snail, which are biomarkers of epithelial­mesenchymal transition. Furthermore, PLK4 knockdown inactivated the Wnt/ß­catenin pathway in CRC cells in vitro and in vivo, and suppressed the growth of xenograft tumors in nude mice. In conclusion, these results suggested that PLK4 may promote the carcinogenesis and metastasis of CRC, thus indicating that PLK4 may be considered a molecular target for CRC treatment.


Assuntos
Neoplasias Colorretais/metabolismo , Transição Epitelial-Mesenquimal , Proteínas Serina-Treonina Quinases/metabolismo , Via de Sinalização Wnt , Idoso , Animais , Biomarcadores Tumorais/metabolismo , Carcinogênese , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Progressão da Doença , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Metástase Linfática , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Pessoa de Meia-Idade , Proteínas Serina-Treonina Quinases/genética , Ensaios Antitumorais Modelo de Xenoenxerto
14.
Cell Death Dis ; 8(2): e2628, 2017 02 23.
Artigo em Inglês | MEDLINE | ID: mdl-28230864

RESUMO

Dicer, a member of the RNase III family of endoribonucleases, has an important role in regulating methylation of CpG islands in mammal cancer cells. However, the underlying mechanism of action remains unclear. In this study, we demonstrated that upregulation of Dicer in cholangiocarcinoma (CCA) cells and its translocation to nuclues to interact with heterochromatin protein 1α (HP1α). The nuclear Dicer/HP1α complex appeared to promote both H3K9 trimethylation and DNA methylation of the secreted frizzled-related protein 1 (SFRP1) promoter. The expression of Dicer negatively correlated with that of SFRP1 and it appeared to promote CCA cell proliferation and invasion through repression of SFRP1 gene. High expression of Dicer in tumor tissues was significantly associated with larger tumor size (>3 cm) and lymph node metastasis. Our findings help characterize the role of Dicer in epigenetic regulation and tumorigenesis in the context of CCA.


Assuntos
Neoplasias dos Ductos Biliares/metabolismo , Carcinogênese/metabolismo , Núcleo Celular/metabolismo , Colangiocarcinoma/metabolismo , RNA Helicases DEAD-box/metabolismo , Metilação de DNA/genética , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Proteínas de Membrana/metabolismo , Regiões Promotoras Genéticas/genética , Ribonuclease III/metabolismo , Animais , Neoplasias dos Ductos Biliares/genética , Neoplasias dos Ductos Biliares/patologia , Carcinogênese/genética , Carcinogênese/patologia , Linhagem Celular , Linhagem Celular Tumoral , Núcleo Celular/genética , Proliferação de Células/fisiologia , Colangiocarcinoma/genética , Colangiocarcinoma/patologia , Homólogo 5 da Proteína Cromobox , Proteínas Cromossômicas não Histona/metabolismo , Epigênese Genética/genética , Células HEK293 , Humanos , Metástase Linfática/genética , Metástase Linfática/patologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Invasividade Neoplásica/genética , Invasividade Neoplásica/patologia , Transporte Proteico/fisiologia
15.
Oncotarget ; 7(30): 48107-48119, 2016 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-27385214

RESUMO

Heterochromatin protein 1α (HP1α) is a gene that mediates chromatin conformation, gene silencing and cancer progression. However, little is known regarding the impact of HP1α in the pathogenesis of cholangiocarcinoma (CCA). In the present study, we demonstrate that HP1α is significantly upregulated in CCA tissues and cell lines, while downregulation of HP1α leads to suppression of cell proliferation. Then we find that downregulation of HP1α can decrease H3K9me3 enrichment and DNA methylation rate of secreted frizzled-related protein 1 (SFRP1) promoter, resulting in restoring the expression of SFRP1. Moreover, restoration of SFRP1 expression can suppress CCA cells proliferation. These results provide a mechanistic understanding of the role of HP1α in the pathogenesis of CCA and may offer a novel therapeutic target in this disease.


Assuntos
Colangiocarcinoma/genética , Proteínas Cromossômicas não Histona/metabolismo , Glicoproteínas/metabolismo , Linhagem Celular Tumoral , Proliferação de Células , Colangiocarcinoma/patologia , Homólogo 5 da Proteína Cromobox , Proteínas Cromossômicas não Histona/genética , Regulação para Baixo , Feminino , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Pessoa de Meia-Idade , Transfecção
16.
Ground Water ; 49(2): 219-26, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-20550587

RESUMO

Arsenic is a well-known groundwater contaminant that causes toxicological and carcinogenic effects in humans. Predicting the transport of arsenic in the subsurface is often problematic because of its complex sorption characteristics. Numerous researchers have reported that arsenic sorption on soil material is initially fast and then subsequently slow. A dual-site numerical sorption model was previously developed to describe arsenic desorption from arsenic-contaminated soils in batch experiments in terms of two different release mechanisms. Experiments involving synthetic acid rain leaching of four arsenic-contaminated soil columns were performed to verify the dual-site numerical sorption model in the context of one-dimensional vertical transport. The fitted models successfully simulated the signature long tailings and the two-stage arsenic leaching patterns for all four soil columns. The dual-site sorption model was incorporated within the general solute transport simulation code Modular Three-Dimensional Multispecies (MT3DMS), version 5.10. The resulting version was named MT3DDS and is available for public access. This experimental study has shown that MT3DDS is capable of simulating phase redistribution during transport, and thus provides a new numerical tool for simulating arsenic transport in the subsurface.


Assuntos
Arsênio/análise , Modelos Teóricos , Poluentes do Solo/análise , Monitoramento Ambiental
17.
Environ Toxicol Chem ; 28(6): 1338-45, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19199372

RESUMO

The application of arsenical herbicides has created legacy environmental problems by contaminating soil in some agricultural areas and at various industrial sites. Numerous previous studies have suggested that the adsorption of arsenic by common soil components is largely controlled by kinetic factors. Four arsenic-contaminated soil samples collected from industrial sites were characterized and subjected to sequential leaching using a synthetic acid rain solution in order to study the release of arsenic. A dual-site numerical sorption-desorption model was constructed that describes arsenic desorption from these soils in terms of two different release mechanisms: Release from type I (equilibrium) and type II (kinetic) sorption sites. Arsenic held on both type I and II sorption sites is accessible through extensive acid rain leaching. Arsenic desorption from these sites follows a linear Kd model; the manner of approaching the Kd model, however, differs. Arsenic desorption from type I sites reached equilibrium with the aqueous phase under the physical environment provided by the experiment (shaking for 24 h at 25 degrees C), while desorption from type II sites followed a first-order kinetic pattern when approaching equilibrium. During synthetic acid rain sequential leaching of the soils, type I sites released their sorbed arsenic rapidly and subsequent desorption was dominated by the kinetic release of arsenic from type II sites. This shift in desorption mechanism dominance generated data corresponding to two intersecting straight lines in the n-logC dimension for all four soils. The dual-site desorption model was solved analytically and proven to be successful in simulating sorption processes where two different mechanisms are simultaneously controlling the aqueous concentration of a trace element.


Assuntos
Arsênio/química , Herbicidas/química , Modelos Teóricos , Poluentes do Solo/química
18.
Sci Total Environ ; 405(1-3): 246-54, 2008 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-18706676

RESUMO

Soils from many industrial sites are contaminated with arsenic because of the historical application of herbicide containing arsenic trioxide. The strong affinity of aqueous arsenic species for soil components has led to the retention of significant amounts of arsenic in surface soils decades after the original source application. Soil collected from a site which received a one-time surficial application of arsenical herbicide in the 1950s was investigated to understand the fate of arsenic under natural leaching conditions. Sequential chemical extraction of the contaminated soil revealed that the majority of the arsenic is in its secondary form. The synthetic acid rain leaching of arsenic from the weathered soil can be divided into two distinct stages. During the first stage, the leachate arsenic concentration underwent a rapid decline which suggests an equilibrium-controlled release event. The second leaching stage was marked by a slow, steady release of arsenic, a signature of a kinetically controlled process. A mathematical approach was employed to identify and describe the two distinct arsenic releasing processes (equilibrium desorption and kinetic desorption). This model considers both desorption processes simultaneously and produces leachate arsenic concentrations in good agreement with the measured data. According to the modeling results, 20% of the arsenic remaining in the soil resides in the herbicide source material after five decades of natural leaching; 25% exists on reversible adsorption sites and 55% is present on irreversible adsorption sites.


Assuntos
Arsênio/análise , Monitoramento Ambiental , Herbicidas/análise , Poluentes do Solo/análise , Arsênio/química , Herbicidas/química , Cinética , Modelos Teóricos , Poluentes do Solo/química
19.
J Environ Sci (China) ; 17(4): 662-6, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16158601

RESUMO

A series of simulation experiments of nitrogen transportation, absorption and transformation were conducted, and the different cropping patterns of winter wheat and wastewater irrigation plans were taken into consideration. Based on the experiments, an integrated model of crop growth, roots distribution, water and nitrogen absorption by roots, water and nitrogen movement and transformation in soil-crop system by two-dimension was developed. Parameters and boundary conditions were identified and an effective computing method for optimizing watering and wastewater irrigating plans was provided.


Assuntos
Produtos Agrícolas/química , Nitrogênio/química , Solo , Matemática , Modelos Estatísticos , Água
20.
J Environ Sci (China) ; 15(6): 827-35, 2003 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-14758904

RESUMO

A dynamic composite model for a soil-water system that can be used to simulate the movement of leachate from a landfill. The composite model includes nine sub-models that trace water movement and the migration and transformation of five pollutants (organic N, NH4-, NO3-, NO2-, and Cl-) in saturated and unsaturated soil. The model to simulate the movement of leachate from a landfill in Laogang Town, Shanghai City was used. In this application, the values for the model parameters were obtained by performing a laboratory simulation experiment of water movement and pollutant migration and transformation in soil columns. Soil and leachate obtained from the landfill site and its vicinity were used in the laboratory experiments. The model was then used to simulate leachate movement and pollutant activity during the ten-year period when the landfill was in operation and in the twenty-year period following its closure. The simulation results revealed that the leachate migrated into the groundwater at the rate of 90-100 meters per year. This model can be applied in the design of future landfills in China for the purpose of assessing and forecasting leachate plumes.


Assuntos
Modelos Químicos , Eliminação de Resíduos , Solo/análise , Poluentes da Água/análise , China , Cloretos/química , Simulação por Computador , Compostos de Nitrogênio/química , Movimentos da Água
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