RESUMO
Most microbiologically influenced corrosion (MIC) studies focus on the threat of pinhole leaks caused by MIC pitting. However, microbes can also lead to structural failures. Tetrakis hydroxymethyl phosphonium sulfate (THPS) biocide mitigated the microbial degradation of mechanical properties of X80 steel pipeline by Desulfovibrio ferrophilus (IS5 strain), a very corrosive sulfate reducing bacterium. It was found that 100 ppm (w/w) THPS added to the enriched artificial seawater (EASW) culture medium before incubation resulted in 2.8-log reduction in sessile cell count after a 7-d incubation at 28 °C under anaerobic conditions, leading to 94% uniform corrosion rate reduction (from 1.3 to 0.07 mm/a), and 84% pitting corrosion rate reduction (from 0.70 to 0.11 mm/a). The X80 dogbone coupon incubated with 100 ppm THPS for 7 d suffered 3% loss in ultimate tensile strain and 0% loss in ultimate tensile strength compared with the abiotic control in EASW. In comparison, the no-treatment X80 dogbone coupon suffered losses of 13% in ultimate tensile strain and 6% in ultimate tensile stress, demonstrating very good THPS efficacy.
Assuntos
Biodegradação Ambiental , Desulfovibrio , Desinfetantes , Aço , Aço/química , Corrosão , Desulfovibrio/metabolismo , Desulfovibrio/efeitos dos fármacos , Desinfetantes/farmacologia , Resistência à Tração , CarbonoRESUMO
The discovery of alternative medicines with fewer adverse effects is urgently needed for rheumatoid arthritis (RA). Sophoridine (SR), the naturally occurring quinolizidine alkaloid isolated from the leguminous sophora species, has been demonstrated to possess a wide range of pharmacological activities. However, the effect of SR on RA remains unknown. In this study, the collagen-induced arthritis (CIA) rat model and tumor necrosis factor alpha (TNFα)-induced fibroblast-like synoviocytes (FLSs) were utilized to investigate the inhibitory effect of SR on RA. The anti-arthritic effect of SR was evaluated using the CIA rat model in vivo and TNFα-stimulated FLSs in vitro. Mechanistically, potential therapeutic targets and pathways of SR in RA were analyzed through drug target databases and disease databases, and validation was carried out through immunofluorescence, immunohistochemistry, and Western blot. The in vivo results revealed that SR treatment effectively ameliorated synovial inflammation and bone erosion in rats with CIA. The in vitro studies showed that SR could significantly suppress the proliferation and migration in TNFα-induced arthritic FLSs. Mechanistically, SR treatment efficiently inhibited the activation of MAPKs (JNK and p38) and NF-κB pathways in TNFα-induced arthritic FLSs. These findings were further substantiated by Immunohistochemistry results in the CIA rat. SR exerts an anti-arthritic effect in CIA rats through inhibition of the pathogenic characteristic of arthritic FLSs via suppressing NF-κB and MAPKs (JNK and p38) signaling pathways. SR may have a great potential for development as a novel therapeutic agent for RA treatment.
Assuntos
Alcaloides , Artrite Experimental , Artrite Reumatoide , Fibroblastos , Matrinas , NF-kappa B , Quinolizinas , Sinoviócitos , Fator de Necrose Tumoral alfa , Animais , Sinoviócitos/efeitos dos fármacos , Artrite Experimental/tratamento farmacológico , Alcaloides/farmacologia , Ratos , Quinolizinas/farmacologia , Fator de Necrose Tumoral alfa/metabolismo , NF-kappa B/metabolismo , Fibroblastos/efeitos dos fármacos , Artrite Reumatoide/tratamento farmacológico , Masculino , Proliferação de Células/efeitos dos fármacos , Sophora/química , Ratos Sprague-DawleyRESUMO
Context: Kaempferitrinis (KF) is a bioactive flavonoid and possesses numerous pharmacological activities. However, whether KF affects the activity of human liver cytochrome P450 (CYP) enzymes remains unclear. Objective: This study investigates the effects of KF on eight major CYP isoforms in human liver microsomes (HLMs). Materials and methods: In vitro, HLMs were used to investigate the inhibitory effects of KF (100 µM) on the eight human liver CYP isoforms (i.e., 1A2, 3A4, 2A6, 2E1, 2D6, 2C9, 2C19, and 2C8), and corresponding probe substrates were used. Enzyme kinetic studies (0-50 µM of KF) were conducted to determine the inhibition mode of KF on CYP enzymes. Results: The results showed that KF inhibited the activity of CYP1A2, 3A4, and 2C9, with IC50 values of 20.56, 13.87, and 14.62 µM, respectively, but that other CYP isoforms were not affected. Enzyme kinetic studies showed that KF was not only a noncompetitive inhibitor of CYP3A4, but also a competitive inhibitor of CYP1A2 and 2C9, with Ki values of 7.11, 10.24, and 7.58 µM, respectively. In addition, KF is a time-dependent inhibitor for CYP3A4 with KI/Kinact value of 10.85/0.036 min/µM. Discussion: The in vitro studies of KF with CYP isoforms indicate that KF has the potential to cause pharmacokinetic drug interactions with other co-administered drugs metabolized by CYP1A2, 3A4, and 2C9. Conclusion: It is recommended that KF should not be used with other drugs metabolized by CYP1A2, 3A4, and 2C9. Further clinical studies are needed to evaluate the significance of this interaction.
Assuntos
Citocromo P-450 CYP1A2/metabolismo , Citocromo P-450 CYP2C9/metabolismo , Citocromo P-450 CYP3A/metabolismo , Inibidores das Enzimas do Citocromo P-450/farmacologia , Quempferóis/farmacologia , Fígado/efeitos dos fármacos , Humanos , Técnicas In Vitro , Isoenzimas , Cinética , Fígado/enzimologia , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/enzimologiaRESUMO
News articles containing data visualizations play an important role in informing the public on issues ranging from public health to politics. Recent research on the persuasive appeal of data visualizations suggests that prior attitudes can be notoriously difficult to change. Inspired by an NYT article, we designed two experiments to evaluate the impact of elicitation and contrasting narratives on attitude change, recall, and engagement. We hypothesized that eliciting prior beliefs leads to more elaborative thinking that ultimately results in higher attitude change, better recall, and engagement. Our findings revealed that visual elicitation leads to higher engagement in terms of feelings of surprise. While there is an overall attitude change across all experiment conditions, we did not observe a significant effect of belief elicitation on attitude change. With regard to recall error, while participants in the draw trend elicitation exhibited significantly lower recall error than participants in the categorize trend condition, we found no significant difference in recall error when comparing elicitation conditions to no elicitation. In a follow-up study, we added contrasting narratives with the purpose of making the main visualization (communicating data on the focal issue) appear strikingly different. Compared to the results of Study 1, we found that contrasting narratives improved engagement in terms of surprise and interest but interestingly resulted in higher recall error and no significant change in attitude. We discuss the effects of elicitation and contrasting narratives in the context of topic involvement and the strengths of temporal trends encoded in the data visualization.
RESUMO
Riboflavin (RF), as a common electron mediator that can accelerate extracellular electron transfer (EET), is usually used as a probe to confirm EET-microbiologically influenced corrosion (MIC). However, the acceleration mechanism of RF on EET-MIC is still unclear, especially the effect on gene expression in bacteria. In this study, a 13-mer antimicrobial peptide E6 and tetrakis hydroxymethyl phosphonium sulfate (THPS) were used as new tools to investigate the acceleration mechanism of RF on Fe0-to-microbe EET in corrosion of EH36 steel caused by Pseudomonas aeruginosa. 60 min after 20 ppm (v/v) THPS and 20 ppm THPS & 100 nM E6 were injected into P. aeruginosa 1 and P. aeruginosa 2 (two glass bottles containing P. aeruginosa with different treatments) at the 3-d incubation, respectively, P. aeruginosa 1 and P. aeruginosa 2 had a similar planktonic cell count, whereas the sessile cell count in P. aeruginosa 1 was 1.3 log higher than that in P. aeruginosa 2. After the 3-d pre-growth and subsequent 7-d incubation, the addition of 20 ppm (w/w) RF increased the weight loss and maximum pit depth of EH36 steel in P. aeruginosa 1 by 0.7 mg cm-2 and 4.1 µm, respectively, while only increasing those in P. aeruginosa 2 by 0.4 mg cm-2 and 1.7 µm, respectively. This suggests that RF can be utilized by P. aeruginosa biofilms since the corrosion rate should be elevated by the same value if it only acts on the planktonic cells. Furthermore, the EET capacity of P. aeruginosa biofilm was enhanced by RF because the protein expression of cytochrome c (Cyt c) gene in sessile cells was significantly increased in the presence of RF, which accelerated EET-MIC by P. aeruginosa against EH36 steel.
Assuntos
Pseudomonas aeruginosa , Riboflavina , Aço , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/fisiologia , Corrosão , Transporte de Elétrons/efeitos dos fármacos , Biofilmes/efeitos dos fármacosRESUMO
Wear particles generated from the surface of implanted prostheses can lead to peri-implant osteolysis and subsequent aseptic loosening. In the inflammatory environment, extensive formation and activation of osteoclasts are considered the underlying cause of peri-implant osteolysis. Current medications targeting osteoclasts for the treatment of particle-induced bone resorption are not ideal due to significant side effects. Therefore, there is an urgent need to develop more effective drugs with fewer side effects. Norcantharidin (NCTD), a derivative of cantharidin extracted from blister beetles, is currently primarily used for the treatment of solid tumors in clinical settings. However, the potential role of NCTD in treating aseptic loosening of the prosthesis has not been reported. In this study, the in vitro results demonstrated that NCTD could effectively inhibit the formation of osteoclasts and bone resorption induced by the RANKL. Consistently, NCTD strongly inhibited RANKL-induced mRNA and protein levels of c-Fos and NFATc1, concomitant with reduced expression of osteoclast specific genes including TRAP, CTR and CTSK. The in vivo data showed that NCTD exerted significant protective actions against titanium particle-induced inflammation and subsequent osteolysis. The molecular mechanism investigation revealed that NCTD could suppress the activations of RANKL-induced MAPK (p38, ERK). Overall, these findings support the potential use of NCTD for the treatment of aseptic loosening following total joint arthroplasty.
Assuntos
Reabsorção Óssea , Compostos Bicíclicos Heterocíclicos com Pontes , Osteólise , Animais , Camundongos , Osteoclastos , Osteólise/induzido quimicamente , Osteólise/tratamento farmacológico , Osteólise/metabolismo , Titânio/efeitos adversos , NF-kappa B/metabolismo , Reabsorção Óssea/induzido quimicamente , Reabsorção Óssea/tratamento farmacológico , Reabsorção Óssea/patologia , Ligante RANK/metabolismo , Osteogênese , Camundongos Endogâmicos C57BLRESUMO
The effect of methanogenic archaea (Methanococcus maripaludis) on corrosion behavior of 316L stainless steel under different concentrations of organic electron donor (acetate) was investigated. The results showed that M. maripaludis can survive by utilizing 316L SS as an alternative energy source. The extracellular electron transfer from 316L SS relies on redox-active substances secreted by M. maripaludis. Corrosion of 316L SS is promoted along with decrease of acetate concentration. M. maripaludis causes severe pitting corrosion of 316L SS in the absence of acetate due to that more redox-active substances are secreted, which has little relationship with the M. maripaludis biofilm.
Assuntos
Elétrons , Aço Inoxidável , Corrosão , Biofilmes , Água do MarRESUMO
Carbon starvation can affect the activity of microbes, thereby affecting the metabolism and the extracellular electron transfer (EET) process of biofilm. In the present work, the microbiologically influenced corrosion (MIC) behavior of nickel (Ni) was investigated under organic carbon starvation by Desulfovibrio vulgaris. Starved D. vulgaris biofilm was more aggressive. Extreme carbon starvation (0% CS level) reduced weight loss due to the severe weakening of biofilm. The corrosion rate of Ni (based on weight loss) was sequenced as 10% CS level > 50% CS level > 100 CS level > 0% CS level. Moderate carbon starvation (10% CS level) caused the deepest pit of Ni in all the carbon starvation treatments, with a maximal pit depth of 18.8 µm and a weight loss of 2.8 mg·cm-2 (0.164 mm·y-1). The corrosion current density (icorr) of Ni for the 10% CS level was as high as 1.62 × 10-5 A·cm-2, which was approximately 2.9-fold greater than the full-strength medium (5.45 × 10-6 A·cm-2). The electrochemical data corresponded to the corrosion trend revealed by weight loss. The various experimental data rather convincingly pointed to the Ni MIC of D. vulgaris following the EET-MIC mechanism despite a theoretically low Ecell value (+33 mV).
Assuntos
Desulfovibrio vulgaris , Desulfovibrio , Humanos , Desulfovibrio vulgaris/metabolismo , Níquel , Corrosão , Carbono/metabolismo , Biofilmes , Redução de Peso , AçoRESUMO
The microbial corrosion of marine structural steels (09CrCuSb low alloy steel (LAS) and Q235 carbon steel (CS)) in Desulfovibrio vulgaris medium and Pseudomonas aeruginosa medium based on seawater was investigated. In the D. vulgaris medium, the weight loss and maximum pit depth of 09CrCuSb LAS were 0.59 and 0.56 times as much as those of Q235 CS, respectively. Meanwhile, in the P. aeruginosa medium, the values were 0.53 and 0.67 times, respectively. Compared to Q235 CS, 09CrCuSb LAS contains more alloy elements (Cr, Ni, Cu, Al and Sb), which led to obvious inhibition of sessile bacteria growth but had no effect on planktonic bacteria. The number of live sessile cells on the 09CrCuSb LAS surface was 23.4 % and 26.9 % of that on the Q235 CS surface in the D. vulgaris medium and P. aeruginosa medium, respectively. Fewer sessile cells on the steel surface led to a lower extracellular electron transfer (EET) rate so that less corrosion occurred. In addition, the combined effect of alloying elements on grain refinement and passive film formation also improved the anti-corrosion property of the steels.
Assuntos
Ligas , Aço , Aço/química , Ligas/farmacologia , Elétrons , Biofilmes , Transporte de Elétrons , Pseudomonas aeruginosa/fisiologia , Carbono/químicaRESUMO
In this study, a 13-mer antimicrobial peptide (RRWRIVVIRVRRC) named by E6 was used as an enhancer of a green biocide to mitigate the biocorrosion of EH36 ship steel. Results show that a low concentration of E6 (100 nM) alone was no-biocidal and could not resist the Desulfovibrio vulgaris adhesion on the EH36 steel surface. However, E6 enhanced the bactericidal effect of tetrakis hydroxymethyl phosphonium sulfate (THPS). When E6 and THPS were both added to the bacteria and steel system, both the sessile D. vulgaris cells and biocorrosion rate of EH36 steel decreased significantly. Compared with the 80 ppm THPS alone treatment, the combination of 100 nM E6 + 80 ppm THPS led to an extra 1.6-log reduction in the sessile cell count. Fewer sessile D. vulgaris cells led to a lower extracellular electron transfer (EET) rate, directly resulting in 78% and 83% decreases in weight loss and pit depth of EH36 steel, respectively. E6 saved more than 50% of THPS dosage in this work to achieve a similar biocorrosion mitigation effect on EH36 steel.
Assuntos
Desinfetantes , Desinfetantes/farmacologia , Aço , Navios , Biofilmes , Bactérias , CorrosãoRESUMO
For many households, investing for retirement is one of the most significant decisions and is fraught with uncertainty. In a classic study in behavioral economics, Benartzi and Thaler (1999) found evidence using bar charts that investors exhibit myopic loss aversion in retirement decisions: Investors overly focus on the potential for short-term losses, leading them to invest less in riskier assets and miss out on higher long-term returns. Recently, advances in uncertainty visualizations have shown improvements in decision-making under uncertainty in a variety of tasks. In this paper, we conduct a controlled and incentivized crowdsourced experiment replicating Benartzi and Thaler (1999) and extending it to measure the effect of different uncertainty representations on myopic loss aversion. Consistent with the original study, we find evidence of myopic loss aversion with bar charts and find that participants make better investment decisions with longer evaluation periods. We also find that common uncertainty representations such as interval plots and bar charts achieve the highest mean expected returns while other uncertainty visualizations lead to poorer long-term performance and strong effects on the equity premium. Qualitative feedback further suggests that different uncertainty representations lead to visual reasoning heuristics that can either mitigate or encourage a focus on potential short-term losses. We discuss implications of our results on using uncertainty visualizations for retirement decisions in practice and possible extensions for future work.
Assuntos
Gráficos por Computador , Aposentadoria , Humanos , Investimentos em Saúde , IncertezaRESUMO
Biocorrosion of Cu remains a significant challenge in marine engineering but the mechanism is still not clear. The nutrients in marine environment affect the microbe's growth and the formation of biofilm, and then affect biocorrosion of metal to a large extent. In this study, the effect of NO3- concentration in Pseudomonas aeruginosa (P. aeruginosa) medium on the formation of extracellular polymer substance (EPS) film and biocorrosion of Cu were studied. The experiments results showed that limiting NO3- in culture medium triggered increased EPS film but decreased biocorrosion of Cu induced by P. aeruginosa. With increase of NO3- content in the culture medium, the Cu surface attached less polysaccharides and proteins, but the Cu corrosion rate was accelerated. The weight loss of Cu and the maximum pit depth were both increased with increase of NO3- content. The XPS and XRD analyses indicated that the major corrosion product is Cu2O. The increased corrosion rate with increase of the NO3- level were attributed to the EET-MIC route, the formation of Cu(NH3)2+, and the more loose EPS film.
Assuntos
CobreRESUMO
The eutrophication of seawater is not only harmful to the environment, but also influence microbes' proliferation and then influence biocorrosion of marine engineering materials to a great extent. This study investigated the microbiologically influenced corrosion (MIC) of Cu immersed in the Desulfovibrio vulgaris (a sulfate reducing bacterium) medium with four defined nutritional degrees: total nutrition, P lacking, N lacking, and P&N lacking. When D. vulgaris was cultured in more nutritional medium, more H2S was generated and more serious corrosion of Cu occurred. The concentration of H2S corresponding to the medium with total nutrition was as high as 4.9 × 104(±913.0) ppm. The weight loss of Cu in medium with total nutrition increased by at least 50% compared with other nutritional conditions. The depth of pitting pits on Cu increased obviously with more abundant nutrient elements N and P. The electrochemical tests supported the weight loss and also showed that an obvious passivation zone was formed on the anodic polarization curve. This indicated that a protective film was formed on the surface of Cu against uniform corrosion. The analyses of thermodynamics and experiment data indicated that metabolite MIC (M-MIC) account for the Cu corrosion by D. vulgaris.
Assuntos
Desulfovibrio vulgarisRESUMO
Understanding correlation judgement is important to designing effective visualizations of bivariate data. Prior work on correlation perception has not considered how factors including prior beliefs and uncertainty representation impact such judgements. The present work focuses on the impact of uncertainty communication when judging bivariate visualizations. Specifically, we model how users update their beliefs about variable relationships after seeing a scatterplot with and without uncertainty representation. To model and evaluate the belief updating, we present three studies. Study 1 focuses on a proposed "Line + Cone" visual elicitation method for capturing users' beliefs in an accurate and intuitive fashion. The findings reveal that our proposed method of belief solicitation reduces complexity and accurately captures the users' uncertainty about a range of bivariate relationships. Study 2 leverages the "Line + Cone" elicitation method to measure belief updating on the relationship between different sets of variables when seeing correlation visualization with and without uncertainty representation. We compare changes in users beliefs to the predictions of Bayesian cognitive models which provide normative benchmarks for how users should update their prior beliefs about a relationship in light of observed data. The findings from Study 2 revealed that one of the visualization conditions with uncertainty communication led to users being slightly more confident about their judgement compared to visualization without uncertainty information. Study 3 builds on findings from Study 2 and explores differences in belief update when the bivariate visualization is congruent or incongruent with users' prior belief. Our results highlight the effects of incorporating uncertainty representation, and the potential of measuring belief updating on correlation judgement with Bayesian cognitive models.
RESUMO
Biocorrosion first surfaced in the scientific literature when Richard H. Gaines associated corrosion with bacterial activities in 1910. It is also known as microbiologically influenced corrosion (MIC). In general, it covers two scenarios. One is that microbes cause corrosion directly, which usually means microbes secrete corrosive metabolites or microbes harvest electrons from a metal for respiration to produce energy. In the second scenario, microbes are behind the initiation or acceleration of corrosion caused by a pre-existing corrosive agent such as water and CO2 , by compromising the passive film (often a metal oxide film on a metal). MIC is caused by microbial biofilms. It is everywhere around us. This work dissects some notable examples with perspectives.
Assuntos
Bactérias , Biofilmes , Bactérias/genética , Corrosão , MetaisRESUMO
Hierarchical clustering is an important technique to organize big data for exploratory data analysis. However, existing one-size-fits-all hierarchical clustering methods often fail to meet the diverse needs of different users. To address this challenge, we present an interactive steering method to visually supervise constrained hierarchical clustering by utilizing both public knowledge (e.g., Wikipedia) and private knowledge from users. The novelty of our approach includes 1) automatically constructing constraints for hierarchical clustering using knowledge (knowledge-driven) and intrinsic data distribution (data-driven), and 2) enabling the interactive steering of clustering through a visual interface (user-driven). Our method first maps each data item to the most relevant items in a knowledge base. An initial constraint tree is then extracted using the ant colony optimization algorithm. The algorithm balances the tree width and depth and covers the data items with high confidence. Given the constraint tree, the data items are hierarchically clustered using evolutionary Bayesian rose tree. To clearly convey the hierarchical clustering results, an uncertainty-aware tree visualization has been developed to enable users to quickly locate the most uncertain sub-hierarchies and interactively improve them. The quantitative evaluation and case study demonstrate that the proposed approach facilitates the building of customized clustering trees in an efficient and effective manner.
RESUMO
The corrosion behavior of EH40 steel in seawater enriched with Methanococcus maripaludis was investigated through electrochemical methods and surface analysis techniques. The results revealed that the hydrogenotrophic M. maripaludis strain can utilize acetate as an alternative energy source. Corrosion of EH40 steel is initially inhibited, but prolonged exposure with the methanogen leads to an eventual corrosion propagation. During the early stage of immersion in M. maripaludis culture medium, the formation of a protective corrosion products film inhibits EH40 steel corrosion. The presence of M. maripaludis promotes both anodic and cathodic reactions of EH40 steel in the late stage of exposure. Surface analyses revealed that pitting corrosion is closely related to uneven distribution of M. maripaludis biofilm on EH40 steel surface.
Assuntos
Mathanococcus/fisiologia , Água do Mar/química , Água do Mar/microbiologia , Aço/química , Biofilmes , Corrosão , EletroquímicaRESUMO
Microbially catalyzed corrosion of metals is a substantial economic concern. Aerobic microbes primarily enhance Fe0 oxidation through indirect mechanisms and their impact appears to be limited compared to anaerobic microbes. Several anaerobic mechanisms are known to accelerate Fe0 oxidation. Microbes can consume H2 abiotically generated from the oxidation of Fe0. Microbial H2 removal makes continued Fe0 oxidation more thermodynamically favorable. Extracellular hydrogenases further accelerate Fe0 oxidation. Organic electron shuttles such as flavins, phenazines, and possibly humic substances may replace H2 as the electron carrier between Fe0 and cells. Direct Fe0-to-microbe electron transfer is also possible. Which of these anaerobic mechanisms predominates in model pure culture isolates is typically poorly documented because of a lack of functional genetic studies. Microbial mechanisms for Fe0 oxidation may also apply to some other metals. An ultimate goal of microbial metal corrosion research is to develop molecular tools to diagnose the occurrence, mechanisms, and rates of metal corrosion to guide the implementation of the most effective mitigation strategies. A systems biology approach that includes innovative isolation and characterization methods, as well as functional genomic investigations, will be required in order to identify the diagnostic features to be gleaned from meta-omic analysis of corroding materials. A better understanding of microbial metal corrosion mechanisms is expected to lead to new corrosion mitigation strategies. The understanding of the corrosion microbiome is clearly in its infancy, but interdisciplinary electrochemical, microbiological, and molecular tools are available to make rapid progress in this field.
Assuntos
Metais , Microbiota , Corrosão , Transporte de Elétrons , OxirreduçãoRESUMO
An intelligent narrow pH-triggered multilayer film was prepared on magnesium alloys, aiming to solve the implant infections during the implantation period and improve the corrosion resistance of magnesium alloys. The encapsulation of ibuprofen by chitosan (IBU@CS) makes the release of IBU sensitive to narrow pH (pH 6.8-7.4). Positive charged IBU@CS was assembled with heparin (Hep) to fabricate (Hep/IBU@CS)10 film on AZ31 alloys using layer-by-layer method. The microstructure, composition and anticorrosion properties of the film were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and electrochemical experiments. Cellular activity was studied by MTT cell viability assay. The results showed that the Hep/IBU@CS multilayer films improved the corrosion resistance of magnesium alloys. The in vitro test demonstrated that the release of IBU in the film presented narrow pH sensitivity. The films showed no obvious signs of cytotoxicity conformed by the MTT assay and presented antibacterial properties. These preliminary results demonstrate the potential use of the Hep/IBU@CS multilayer films on magnesium-based implants.
Assuntos
Ibuprofeno , Magnésio , Ligas/farmacologia , Materiais Revestidos Biocompatíveis , Corrosão , Preparações de Ação Retardada , Concentração de Íons de Hidrogênio , Ibuprofeno/farmacologia , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de SuperfícieRESUMO
BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common global malignancies with increasing morbidity and mortality. The purpose of this study was to investigate the expression levels and prognostic value of microRNA-3607 (miR-3607) in patients with HCC. METHODS: The expression of miR-3607 was estimated by quantitative real-time RT-PCR. Survival analysis using the Kaplan-Meier method and Cox regression analysis was conducted to evaluate the prognostic value of miR-3607. The functional role of miR-3607 in HCC progression was further assessed using gain- and loss-of-function experiments. Bioinformatics analysis and a dual-luciferase reporter assay were used to explore the direct targets of miR-3607. RESULTS: miR-3607 expression was found to be significantly decreased in HCC tissues and cells compared with the matched tissues and cells (P < 0.001). The decreased expression of miR-3607 was associated with the patients' tumor size and TNM stage (all P < 0.05). According to the survival curves, patients with low miR-3607 expression had poorer overall survival than those with high levels (log-rank P = 0.012). Moreover, the Cox analysis results indicated that miR-3607 expression was an independent prognostic factor for HCC. The results of cell experiments revealed that the overexpression of miR-3607 in HCC cells led to the inhibited cell proliferation, migration, and invasion. TGFBR1 was identified as a direct target of miR-3607. CONCLUSION: The data of this study indicated that the decreased expression of miR-3607 in HCC predicts poor prognosis and the overexpression of miR-3607 in HCC cells can suppress the tumor progression by targeting TGFBR1. This study provides a novel insight into the prognosis and treatment of HCC, and miR-3607 serves as a candidate prognostic biomarker and therapeutic target of HCC.