Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 122
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Environ Sci Technol ; 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31751130

RESUMO

Oil sands (OS) are an important type of heavy oil deposit, whose operations in Alberta, Canada were recently found to be a large source of secondary organic aerosol (SOA). However, SOA formation from the OS mining, processing, and subsequent tailings, especially in the presence of NOx, remains unclear. Here, photooxidation experiments for OS-related precursors under high-NOx conditions were performed using an oxidation flow reactor, in which ~95% of peroxy radicals (RO2) react with NO. The SOA yields under high-NOx conditions were found to be lower than yields under low-NOx conditions for all precursors, which is likely due to the higher volatilities of the products from the RO2+NO pathway compared with RO2+HO2. The SOA yields under high-NOx conditions show a strong dependence on preexisting surface area (not observed in previous low-NOx experiments), again attributed to the higher product volatilities. Comparing the mass spectra of SOA formed from different precursors, we conclude that the fraction of m/z > 80 (F80) can be used as a parameter to separate different types of SOA in the region. In addition, particle-phase organic nitrate (pON) was found to be an important component (9%-23%) of OS SOA formed under high-NOx conditions. These results have implications for better understanding the atmospheric processing of OS emissions.

2.
Environ Sci Technol ; 2019 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-31756294

RESUMO

The environmental risks and health impacts associated with particulate organophosphate flame retardants (OPFRs), which are ubiquitous in the global atmosphere, have not been adequately assessed due to the lack of data on the reaction kinetics, products and toxicity associated with their atmospheric transformations. Here, the importance of such transformations for OPFRs are explored by investigating the reaction kinetics, degradation chemical mechanisms and toxicological evolution of two OPFRs (2-ethylhexyl diphenyl phosphate (EHDP) and diphenyl phosphate (DPhP)) coated on (NH4)2SO4 particles upon heterogeneous OH oxidation. The derived reaction rate constants for the heterogeneous loss of EHDP and DPhP are (1.12±0.22)×10-12 and (2.33±0.14)×10-12 cm3 molecules-1 s-1, respectively. Using recently developed real-time particle chemical composition measurements, particulate products from heterogeneous photooxidation and the associated degradation mechanisms for particulate OPFRs are reported for the first time. Subsequent cytotoxicity analysis of the unreacted and oxidized OPFR particles indicated that the overall particle cytotoxicity was reduced by up to 94% with heterogeneous photooxidation, likely due to a significantly lower cytotoxicity associated with the oxidized OPFR products relative to the parent OPFRs. The present work not only provides guidance for future field sampling for the detection of transformation products of OPFRs, but also strongly supports the ongoing risk assessment of these emerging chemicals and most critically, their products.

3.
Opt Express ; 27(20): 27459-27476, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31684512

RESUMO

The ray-optics (RO) model is a reasonable method to calculate optical force in geometrical optics regime. However, the RO model fails to calculate the optical force produced by diffractive optical field and other arbitrary structured light beams. We propose the Fourier ray (FR) method to calculate the optical force for arbitrary incident beams. Combining the Fourier optics and the geometrical optics, the FRs are defined as rays that inlay on the plane waves weighted by the Fourier angular spectrum of the incident beam. According to traditional RO model and FR method, we can analyze optical forces on a microsphere immersed in various beams. To validate the FR method, forces of the fundamental Gaussian beam and Airy beam are respectively calculated and compared with traditional method. In addition, optical forces in three arbitrary structured light beams are demonstrated as well. Our simulations show that the FR method is able to evaluate the optical forces generated by diffractive optical field and complex structured light beams, and give a solid prediction of their trapping performances. In RO regime, the Fourier ray method is a universal method to predict the interaction between bead and complex optical field.

4.
Lab Chip ; 19(23): 3974-3978, 2019 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-31659359

RESUMO

Carbon dots with different emission fluorescence have a great number of potential applications for various areas from in vitro imaging and biotherapy, due to the good biosafety of red fluorescent CDs, to efficient ion detection and photocatalysis, due to the excellent photoluminescence properties of blue fluorescent carbon dots. Traditional methods for the synthesis of full-spectrum carbon dots require 24 h of synthesis and complex column chromatography. In this paper, a facile and efficient microfluidic method to continuously synthesize small and uniform carbon dots with full-spectrum emission fluorescence is developed for the first time. The synthesis process could be reduced to 20 minutes. Through XPS analysis and DFT calculations, it is quantitatively revealed that the number of primary amino groups determines the energy gap of the carbon dots and thus determines the fluorescence emission wavelength of the carbon dots. Applications for precise Fe3+ detection and in vitro bio-imaging were successfully implemented, showing great potential application value of the carbon dots.

5.
Cell Death Dis ; 10(10): 752, 2019 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-31582742

RESUMO

Long non-coding RNAs (lncRNAs) have been suggested as important regulators of cancer development and progression in hepatocellular carcinoma (HCC). Nevertheless, the clinical value and biological roles of LINC00978 in HCC remain unclear. In this study, we detected the expression of LINC00978 in tumor tissues and serum of HCC patients, examined the roles of LINC00978 in HCC progression and elucidated the underlying molecular mechanisms. We found that LINC00978 expression was upregulated in tumor tissues and serum of HCC patients. Higher serum levels of LINC00978 could distinguish HCC patients from hepatitis and liver cirrhosis patients and healthy controls. LINC00978 knockdown inhibited HCC cell proliferation, migration and invasion while promoted cell cycle arrest and apoptosis. Overexpression of LINC00978 led to the opposite effects. LINC00978 knockdown also inhibited HCC growth and metastasis in mouse tumor models. Mechanistically, LINC00978 bound to EZH2 and mediated its accumulation at the promoter region of p21 and E-cadherin genes, leading to the trimethylation of H27K3 and the inhibition of p21 and E-cadherin expression. Moreover, the simultaneous depletion of p21 and E-cadherin expression reversed the inhibitory effects of LINC00978 knockdown on HCC cell proliferation, migration, and invasion. Taken together, these findings suggest that LINC00978 promotes HCC progression by inhibiting p21 and E-cadherin expression via EZH2-mediated epigenetic silencing. LINC00978 may represent a novel biomarker for HCC diagnosis, prognosis, and therapy.

6.
Brain Behav ; 9(9): e01369, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31397082

RESUMO

OBJECTIVES: Interleukin-33, a newly identified member of interleukin-1 family, had been confirmed to play a crucial role in regulating inflammatory responses in various disease. However, the exact role of interleukin-33 in the disease process of acute ischemic stroke still remains unclear. This study aims to demonstrate the relationship between interleukin-33 levels and long-term functional outcome as well as ischemic stroke recurrence. METHODS: Three hundred and four first-ever acute ischemic stroke patients were recruited and basic information and history of all subjects taken within 72 hr on admission. The functional outcome was estimated by Barthel index. The multivariate logistic regression was used to analyze the prognosis, while the Cox proportional hazard model was applied to assess the recurrence risk. RESULTS: Out of 304 subjects, 259 patients successfully completed scheduled two-year follow-up. We found that higher interleukin-33 levels correlated positively with better prognosis as compared with those with lower interleukin-33 levels who presented with poorer outcome (62.45 ± 20.50 ng/ml vs. 51.58 ± 19.16 ng/ml, p < .001). After adjustment of all confounders, interleukin-33 was associated with the one-year prognosis with an adjusted odds ratio of 0.956 (95% confidence interval, 0.937-0.976, p < .001). Furthermore, interleukin-33 levels were also closely related to recurrent ischemic stroke with an adjusted hazard ratio of 0.979 (95% confidence interval, 0.961-0.997, p = .025). CONCLUSIONS: IL-33 can be used to predict the long-term outcomes and ischemic stroke recurrence in first-ever acute ischemic stroke patients.

7.
Angew Chem Int Ed Engl ; 58(38): 13584-13589, 2019 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-31329345

RESUMO

Although sodium ion batteries (SIBs) possess many beneficial features, their rate performance, cycling stability, and safety need improvement for commercial applications. Based on the mechanisms of the sodium ions storage in carbon materials, herein we present a multiple active sites decorated amorphous carbon (MAC) with rich structural defects and heteroatom doping as an anode material for SIBs. The full utilization of fast bonding-debonding processes between the active sites and sodium ions could bring a capacitive strategy to achieve superior sodium storage properties. Consequently, after materials characterization and electrochemical evaluation, the as-prepared electrode could deliver high rate and long-life performance. This active-site-related design could be extended to other types of electrode materials, thereby contributing to future practical SIB applications.

8.
Environ Pollut ; 252(Pt A): 236-244, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31153028

RESUMO

Current air quality models usually underestimate the concentration of ambient air sulfate, but the cause of this underestimation remains unclear. One reason for the underestimation is that the sulfate formation mechanism in the models is incomplete, and does not adequately consider the impact of the synergistic effects of high concentrations of multiple pollutants on sulfate formation. In this work, the roles of gaseous NO2, NH3 and solution ionic strength in the formation of sulfate in the aqueous phase were quantitatively investigated using a glass reactor and a 30 m3 smog chamber, separately. The results showed that sulfate formation was enhanced to different degrees in the presence of gas-phase NO2, NH3 and their coexistence as solutes in both liquid solution and aerosol water. NH3 enhances the aqueous oxidation of SO2 by NO2 mainly by accelerating the uptake of SO2 through increased solubility. More importantly, we found that high ionic strength in aerosol water could significantly accelerate the aqueous oxidation of SO2, resulting in unexpectedly high S(VI) formation rates. We estimate that under severe haze conditions, heterogeneous oxidation of SO2 by NO2 on aerosols may be much shorter than that through gas phase oxidation by OH, aided by high ionic strengths in aerosols. Considering the existence of complex air pollution conditions with high concentrations of NO2, NH3 and aerosol water, as expected in typical urban and suburban settings, the sulfate formation mechanisms revealed in the present work should be incorporated into air quality models to improve the prediction of sulfate concentrations.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar/análise , Amônia/química , Monitoramento Ambiental/métodos , Nitritos/química , Sulfatos/análise , Dióxido de Enxofre/química , Aerossóis/análise , Concentração Osmolar , Oxirredução , Material Particulado/análise , Solubilidade , Sulfatos/química , Água
9.
Environ Pollut ; 252(Pt B): 1902-1909, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31227346

RESUMO

Inhalation exposure to flame retardants used as additives to minimize fire risk and plasticizers is ubiquitous in human daily activities, but has not been adequately assessed. To address this research gap, the present study conducted an assessment of human health risk for four age groups through inhalation exposure to size fractionated particle-bound and gaseous halogenated flame retardants (polybrominated diphenyl ethers (PBDEs) and alternative halogenated flame retardants (AHFRs)) and organophosphate esters (OPEs) at indoor and outdoor environments (school, office, and residence) in three districts of a megacity (Guangzhou, China). Results demonstrated that OPEs were the dominant components among all targets. Indoor daily intakes of PBDEs and OPEs were 13-16 times greater than outdoor levels for all age groups. Gaseous OPEs contributed significantly greater than particle-bound compounds to daily intakes of all target compounds. Based on the different life scenarios, hazard quotient (HQ) and incremental life cancer risk (ILCR) from adults exposure to PBDEs and OPEs in indoor and outdoor settings were the greatest, followed by adolescents, children, and seniors. The estimated HQ and ILCR for all age groups both indoors and outdoors were lower than the safe level (HQ = 1 and ILCR = 10-6), indicating that the potential health risk for local residents in Guangzhou via inhalation exposure to atmospheric halogenated flame retardants and OPEs was low.


Assuntos
Retardadores de Chama/análise , Éteres Difenil Halogenados/análise , Exposição por Inalação/efeitos adversos , Exposição por Inalação/análise , Organofosfatos/análise , Plastificantes/análise , Adolescente , Adulto , Poluição do Ar em Ambientes Fechados/análise , Criança , China , Gases , Habitação , Humanos , Pessoa de Meia-Idade , Medição de Risco , Adulto Jovem
10.
Environ Sci Technol ; 53(12): 6794-6803, 2019 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-31117542

RESUMO

The current uncertainties in the reactivity and atmospheric persistence of particle-associated chemicals present a challenge for the prediction of long-range transport and deposition of emerging chemicals such as organophosphate flame retardants, which are ubiquitous in the global environment. Here, the OH-initiated heterogeneous oxidation kinetics of organophosphate flame retardants (OPFRs) coated on inert (NH4)2SO4 and redox-active FeSO4 particles were systematically determined as a function of relative humidity (RH). The derived reaction rate constants for the heterogeneous loss of tricresyl phosphate (TCP; kTCP) and tris(2-butoxyethyl) phosphate (TBEP; kTBEP) were in the range of (2.69-3.57) × 10-12 and (3.06-5.55) × 10-12 cm3 molecules-1 s-1, respectively, depending on the RH and coexisting Fe(II) content. The kTCP (coated on (NH4)2SO4) was relatively constant over the investigated RH range while kTBEP was enhanced by up to 19% with increasing RH. For both OPFRs, the presence of Fe(II) enhanced their k by up to 53% over inert (NH4)2SO4. These enhancement effects (RH and Fe(II)) were attributed to fundamental changes in the organic phase state (higher RH lowered particle viscosity) and Fenton-type chemistry which resulted in the formation of reactive oxygen species, respectively. Such findings serve to emphasize the importance of ambient RH, the phase state of particle-bound organics in general, and the presence of coexisting metallic species for an accurate description of the degradation kinetics and aging of particulate OPFRs in models used to evaluate their atmospheric persistence.


Assuntos
Retardadores de Chama , Umidade , Ferro , Organofosfatos , Oxirredução
11.
Carbohydr Polym ; 217: 232-239, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31079681

RESUMO

Heparan sulfate (HS) and heparin, representative members of the glycosaminoglycans, possess distinct biological functions in terms of their specific interactions with hundreds of binding proteins. However, the structural properties of HS and heparin are complex due to their variable repeating motifs, different chain lengths and sulfation patterns. A concise chemoenzymatic approach has been developed to obtain well-defined low molecular weight (LMW) HS analogues. Pasteurella multocida heparosan synthase-2 (PmHS2) was utilized to fabricate the HS backbones with controllable chain lengths ranging from 14mer to 26mer. Moreover, regioselective and overall sulfation were conducted by chemical approach. The persulfated HS analogues exhibited more potent beta-site amyloid precursor protein (APP)-cleaving enzyme-1 (BACE-1) inhibitory activity than heparin and enoxaparin, and enhanced BACE-1 inhibitions were also found with the increasing molecular size of the HS analogues. This approach supplies the promising LMW HS analogues for the potential development of novel anti-Alzheimer's drugs.


Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Heparitina Sulfato/análogos & derivados , Inibidores de Proteases/química , Sequência de Carboidratos , Glicosiltransferases/química , Heparitina Sulfato/síntese química , Humanos , Peso Molecular , Pasteurella multocida/enzimologia , Inibidores de Proteases/síntese química
12.
Exp Eye Res ; 184: 258-265, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31077713

RESUMO

PURPOSE: The occurrence of presbyopia and cataract is closely related to changes in the mechanical properties of the crystalline lens. There are no established methods so far for in vivo assessment. By introducing ultrasound elastography, we proposed group velocity (Vg) of an induced shear wave as a new biomarker to characterize the mechanical properties of the lens in our previous study. Here, we investigated the effect of the ultrasound frequency on measurement accuracy and validated the results with a conventional ex vivo compression testing. We also demonstrated a change trend in Vg and its correlation with age in a rabbit model. METHODS: Eight New Zealand white rabbits were fed normally from the fourth to seventh month. An ultrasound elastography system was developed to measure Vgin vivo on every eye once per month. The performances when using a high-frequency (L22-11v) and low-frequency (L11-4v) probe were compared. Rabbits were sacrificed after in vivo measurements by the end of the seventh month and this was followed by ex vivo ultrasound measurements and conventional compression tests on the extracted lenses. RESULTS: The results demonstrated that there were no significance differences in Vg between measurements with high-frequency (USE-HF) and low-frequency (USE-LF) probes in the same month-age group. The mean Vg and the standard deviation of four rabbits that were 7 months old were 2.37 ±â€¯0.24  m/s, 2.36 ±â€¯0.25 m/s, 2.43 ±â€¯0.26 m/s and 2.44 ±â€¯0.38 m/s, with USE-HF for ex vivo and in vivo measurements and USE-LF for ex vivo and in vivo measurements, respectively. There were no significant differences (p > 0.05) and they were all in agreement with the results of compression tests, which was 16.16 ±â€¯1.84 kPa in Young's modulus. The results also showed that Vg increased with age. In combination with the results of our previous study, Vg showed a relatively sharp increase from 2 to 5 months, while it had a slight increase from 5 to 7 months. CONCLUSIONS: The USE-HF and USE-LF has comparable accuracy in Vg measurements while USE-HF had an advantage regarding better spatial resolution. The change trend of Vg was in accord with the growth phase of New Zealand white rabbits, which usually results in sexual maturity at 5 months old. This implies that Vg can be used as a biomarker parameter for evaluating the mechanical properties of the lens undergoing physiological changes.

13.
Zhongguo Zhong Yao Za Zhi ; 44(3): 553-558, 2019 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-30989922

RESUMO

Modern pharmacological studies have shown that Shengmai San has the effects of enhancing immunity and improving blood circulation, and Curcumae Longae Rhizoma(Jianghuang) has anti-inflammatory, anti-cancer, anti-oxidation and other functions. Shengmai San combined with Jianghuang is a new research direction in the study of anti-tumor of traditional Chinese medicines. The main treatment for nasopharyngeal carcinoma is radiation therapy, but radiation therapy can cause a variety of side effects, and it also changes the composition of the intestinal flora. In this study, the 16 s rDNA sequencing platform was used to perform macro-sequence sequencing of the intestinal flora samples of nude mice bearing the veins of Shengmai Jianghuang San, and then the results of intestinal flora data were analyzed to investigate the effect of Shengmai Jianghuang San on tumors. The results showed that Shengmai Jianghuang San combined with irradiation could enhance the therapeutic effect of tumor treatment. Radiation therapy would reduce the total number and diversity of intestinal flora in nude mice, and also change the structure of the flora. Shengmai Jianghuang San could protect the diversity of colonies, and also partially restore the colony imbalance caused by irradiation. This study provides a research idea for Shengmai Jianghuang San as a sensitizing adjuvant for radiotherapy of nasopharyngeal carcinoma.


Assuntos
Medicamentos de Ervas Chinesas/farmacologia , Microbioma Gastrointestinal/efeitos dos fármacos , Carcinoma Nasofaríngeo/radioterapia , Radiossensibilizantes/farmacologia , Animais , Camundongos , Camundongos Nus , Tolerância a Radiação
14.
Nat Commun ; 10(1): 1863, 2019 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-31015411

RESUMO

The oil and gas (O&G) sector represents a large source of greenhouse gas (GHG) emissions globally. However, estimates of O&G emissions rely upon bottom-up approaches, and are rarely evaluated through atmospheric measurements. Here, we use aircraft measurements over the Canadian oil sands (OS) to derive the first top-down, measurement-based determination of the their annual CO2 emissions and intensities. The results indicate that CO2 emission intensities for OS facilities are 13-123% larger than those estimated using publically available data. This leads to 64% higher annual GHG emissions from surface mining operations, and 30% higher overall OS GHG emissions (17 Mt) compared to that reported by industry, despite emissions reporting which uses the most up to date and recommended bottom-up approaches. Given the similarity in bottom-up reporting methods across the entire O&G sector, these results suggest that O&G CO2 emissions inventory data may be more uncertain than previously considered.

15.
Biomed Pharmacother ; 111: 1057-1065, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30841419

RESUMO

Major depressive disorder (MDD) affects ˜16% of the world population. Chronic stressors contribute to reduced hippocampal volumes and increase the risk of developing MDD. Our previous work showed that XYS ameliorates social isolation and chronic unpredictable mild stress (CUMS) induced depressive-like behaviors in rats by regulating hypothalamic-pituitary-adrenal hyperactivation, locus coeruleus -norepinephrine activity and kynurenine/5-hydroxytryptamin balance. Here, we report that CUMS & isolation-treated mice exhibit depressive-like behaviors and show a phenotype of mixed apoptosis/autophagy characteristic in mice hippocampus in vivo. Modified Xiaoyao San (MXS) significantly ameliorates CUMS & social isolation-induced anhedonia, loss of interests, psychomotor retardation and behavioral despair. It suppresses the apoptosis by downregulaing condensation of heterochromatin and reducing hippocampal TdT-mediated dUTP Nick-End Labeling (TUNEL)-positive cells. MSX significantly inhibits mitochondrial outer membrane permeabilization (MOMP) reduces the release of cytochrome C and the shift of apoptosis inducing factor (AIF) from mitochondria to nucleus. Further, it stimulates the formation of autophagosomes and activates the expression of Atg5 and LC3II. Combined silencing of Atg5 and Atg7 dampens MOMP and impaired the anti-apoptotic effects of MXS. In conclusion, MXS ameliorates depressive-like behaviors by triggering autophagy to alleviate neuronal apoptosis. MXS is an effective supplement for MDD treatment, and can be harnessed to enhance autophagy and synergize with antidepressant action.


Assuntos
Antidepressivos/farmacologia , Apoptose/efeitos dos fármacos , Autofagossomos/efeitos dos fármacos , Depressão/tratamento farmacológico , Transtorno Depressivo Maior/tratamento farmacológico , Medicamentos de Ervas Chinesas/farmacologia , Neurônios/efeitos dos fármacos , Animais , Fator de Indução de Apoptose/metabolismo , Autofagossomos/metabolismo , Autofagia/efeitos dos fármacos , Depressão/metabolismo , Transtorno Depressivo Maior/metabolismo , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Neurônios/metabolismo , Permeabilidade/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Estresse Psicológico/tratamento farmacológico , Estresse Psicológico/metabolismo
16.
Environ Sci Technol ; 53(6): 3058-3066, 2019 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-30794751

RESUMO

The health impacts associated with engineered nanoparticles (ENPs) released into the atmosphere have not been adequately assessed. Such impacts could potentially arise from the toxicity associated with condensable atmospheric secondary organic material (SOM), or changes in the SOM composition induced by ENPs. Here, these possibilities are evaluated by investigating the oxidative and toxicological evolution of TiO2 and SiO2 nanoparticles which have been coated with SOM from the O3 or OH initiated oxidation of α-pinene. It was found that pristine SiO2 particles were significantly more cytotoxic compared to pristine TiO2 particles. TiO2 in the dark or under UV irradiation catalytically reacted with the SOM, increasing its O/C by up to 55% over photochemically inert SiO2 while having negligible effects on the overall cytotoxicity. Conversely, the cytotoxicity associated with SiO2 coated with SOM was markedly suppressed (by a factor of 9, at the highest exposure dose) with both increased SOM coating thickness and increased photochemical aging. These suppressing effects (organic coating and photo-oxidation of organics) were attributed to a physical hindrance of SiO2-cell interactions by the SOM and enhanced SOM viscosity and hydrophilicity with continued photo-oxidation, respectively. These findings highlight the importance of atmospheric processes in altering the cytotoxicity of ENPs.


Assuntos
Nanopartículas , Dióxido de Silício , Atmosfera , Oxirredução , Estresse Oxidativo
17.
Oncol Rep ; 41(3): 1638-1648, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30592286

RESUMO

MicroRNAs (miRNAs) play critical roles in the growth, metastasis and therapeutic resistance of liver cancer. Accumulating evidence suggests that miR­498 is aberrantly expressed in several human malignancies. However, the role and underlying mechanism of miR­498 in liver cancer remain unclear. In the present study, we investigated the potential roles and clinical value of miR­498 in liver cancer. We found that the miR­498 expression level was significantly lower in liver cancer patient tissues than that in healthy control tissues. The expression of miR­498 was also decreased in liver cancer cell lines compared to that noted in a normal human normal liver cell line. miR­498 overexpression markedly inhibited liver cancer cell proliferation, migration and invasion. miR­498 overexpression induced cell cycle arrest and apoptosis while it suppressed epithelial­mesenchymal transition (EMT) in liver cancer cells. Bioinformatic analysis and luciferase reporter assay further identified zinc finger E­box binding homeobox 2 (ZEB2) as a novel target of miR­498. Furthermore, ZEB2 knockdown recapitulated the inhibitory effects of miR­498 overexpression in liver cancer cells. ZEB2 overexpression rescued the inhibition of liver cancer cell proliferation, migration, and invasion by miR­498, indicating that ZEB2 acts as a downstream effector of miR­498 in liver cancer cells. Thus, we demonstrated that miR­498 suppresses the growth and metastasis of liver cancer cells, partly at least, by directly targeting ZEB2, suggesting that miR­498 may serve as a potential biomarker for the diagnosis and therapy of liver cancer.


Assuntos
Biomarcadores Tumorais/metabolismo , Carcinoma Hepatocelular/genética , Neoplasias Hepáticas/genética , MicroRNAs/metabolismo , Homeobox 2 de Ligação a E-box com Dedos de Zinco/genética , Idoso , Animais , Apoptose/genética , Biomarcadores Tumorais/genética , Carcinoma Hepatocelular/diagnóstico , Carcinoma Hepatocelular/patologia , Pontos de Checagem do Ciclo Celular/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Biologia Computacional , Conjuntos de Dados como Assunto , Transição Epitelial-Mesenquimal/genética , Feminino , Regulação Neoplásica da Expressão Gênica , Técnicas de Silenciamento de Genes , Humanos , Fígado/patologia , Neoplasias Hepáticas/diagnóstico , Neoplasias Hepáticas/patologia , Masculino , Camundongos Endogâmicos BALB C , Camundongos Nus , MicroRNAs/genética , Pessoa de Meia-Idade , Via de Sinalização Wnt/genética , Ensaios Antitumorais Modelo de Xenoenxerto , Homeobox 2 de Ligação a E-box com Dedos de Zinco/metabolismo
18.
Environ Sci Technol ; 2018 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-30516049

RESUMO

The number and mass size distributions of refractory black carbon (rBC) cores in particles emitted from a diesel vehicle were investigated as a function of particle mobility diameter (dmob) using a single particle soot photometer (SP2) and a differential mobility analyzer (DMA). The thickness and mass of coatings on the rBC cores were characterized. Based on the SP2 and DMA results, the physical properties of particles containing rBC, including effective density (ρeff), mass-mobility exponent (Dm), dynamic shape factor (χ) and mass absorption cross section (MAC) were derived as a function of dmob. At each dmob, the count median diameter (CMD) of the rBC cores was essentially the same as their mass median diameter (MMD), which increased linearly with dmob. The mass of the rBC cores was proportional to the cubic of their dmob. However, coating thickness on rBC cores remained unchanged with dmob, with an average thickness of (28.72±4.81) nm. For particles containing rBC, ρeff decreased and χ increased with dmob. The Dm of particles containing rBC was calculated to be 2.09. At 355 and 532 nm wavelengths, the MAC of the diesel particles containing rBC was inversely dependent on dmob.

19.
ACS Appl Mater Interfaces ; 10(45): 38845-38852, 2018 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-30346130

RESUMO

Developing high-rate anode materials with large capacity for lithium ion batteries (LIBs) is quite necessary for the booming electric vehicles industry. The utilization of stable and conductive hollow structures for electrode composite materials could make the desired performances possible in the future. Thus, in this study, a hollow structured Ni-CoSe2 embedded in N-doped amorphous carbon nanocomposite (Ni-CoSe2@NC) has been successfully synthesized with metal-organic frameworks (MOFs) as precursors. Such strategy integrates both the merits of the multicomponents and the hollow structure; the latter could facilitate both mass and charge transport, and the former (the N-doped carbon) could not only offer plenty of surface defects, improving the surface capacitive contributions, but also stabilize the electrode structure during the charge/discharge processes. As a result, the metal selenide composite delivers outstanding high-rate properties with good stability as the anode for LIBs. The structure and components design could also be extended to other anode composites in the future.

20.
Cancer Manag Res ; 10: 4459-4470, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30349378

RESUMO

Background: Increasing evidence suggests that SALL4 plays oncogenic roles in cancer development and progression. We have previously shown that SALL4 is highly expressed in gastric cancer, and its upregulation is associated with lymph node metastasis and poor prognosis. The role of SALL4 in gastric cancer metastasis and the underlying mechanism remain unclear. Materials and methods: The biological roles of SALL4 in gastric cancer cell mobility, migration, and invasion were investigated by wound healing, transwell migration assay, and Matrigel invasion assay. The effects of SALL4 on epithelial-mesenchymal transition (EMT) in gastric cancer cells were examined by quantitative real-time PCR and Western blot. The downstream target genes of SALL4 were identified by microarray. The regulation of TGF-ß1 by SALL4 in gastric cancer cells was analyzed by luciferase reporter assay and chromatin immunoprecipitation assay. Results: SALL4 knockdown inhibited, while SALL4 overexpression promoted the motility, migration, and invasion abilities of gastric cancer cells in vitro. SALL4 knockdown also suppressed the peritoneal metastasis of gastric cancer cells in nude mice. SALL4 knockdown suppressed, while SALL4 overexpression induced the activation of TGF-ß/SMAD signaling pathway and triggered EMT in gastric cancer cells. TGF-ß1 was identified as a direct target gene of SALL4. The results of chromatin immunoprecipitation study and luciferase reporter assay further confirmed that SALL4 bound to the promoter of TGF-b1 gene and activated its expression. TGF-ß1 knockdown reversed SALL4-mediated promotion of gastric cancer cell motility, migration, and invasion, indicating that TGF-ß1 acts as a downstream effector of SALL4. Furthermore, the expression of TGF-ß1 was found to be closely associated with that of SALL4 in gastric cancer tissues. Conclusion: SALL4 promotes the metastasis of gastric cancer, at least partly, by directly activating TGF-ß1, suggesting that SALL4 may serve as a new target for gastric cancer therapy.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA