The following material is devoted to the generalization of the chaos modeling to random fields in communication channels and its application on the space-time filtering for the incoherent paradigm;that is the purpose ...The following material is devoted to the generalization of the chaos modeling to random fields in communication channels and its application on the space-time filtering for the incoherent paradigm;that is the purpose of this research. The approach, presented hereafter, is based on the “Markovian” trend in modeling of random fields, and it is applied for the first time to the chaos field modeling through the well-known concept of the random “treatment” of deterministic dynamic systems, first presented by A. Kolmogorov, M. Born, etc. The material presents the generalized Stratonovich-Kushner Equations (SKE) for the optimum filtering of chaotic models of random fields and its simplified quasi-optimum solutions. In addition to this, the application of the multi-moment algorithms for quasi-optimum solutions is considered and, it is shown, that for scenarios, when the covariation interval of the input random field is less than the distance between the antenna elements, the gain of the space-time algorithms against their “time” analogies is significant. This is the general result presented in the following.展开更多
Hepatocellular carcinoma(HCC)is one of the most lethal malignant tumours worldwide.The mortality-to-incidence ratio is up to 91.6%in many countries,representing the third leading cause of cancer-related deaths.Systemi...Hepatocellular carcinoma(HCC)is one of the most lethal malignant tumours worldwide.The mortality-to-incidence ratio is up to 91.6%in many countries,representing the third leading cause of cancer-related deaths.Systemic drugs,including the multikinase inhibitors sorafenib and lenvatinib,are first-line drugs used in HCC treatment.Unfortunately,these therapies are ineffective in most cases due to late diagnosis and the development of tumour resistance.Thus,novel pharmacological alternatives are urgently needed.For instance,immune checkpoint inhibitors have provided new approaches targeting cells of the immune system.Furthermore,monoclonal antibodies against programmed cell death-1 have shown benefits in HCC patients.In addition,drug combinations,including first-line treatment and immunotherapy,as well as drug repurposing,are promising novel therapeutic alternatives.Here,we review the current and novel pharmacological approaches to fight HCC.Preclinical studies,as well as approved and ongoing clinical trials for liver cancer treatment,are discussed.The pharmacological opportunities analysed here should lead to significant improvement in HCC therapy.展开更多
This material is aimed to attract attention to the “incoherent approach for power NOMA-RIS-MIMO transmission in wireless channels”. Such kind of approach might be successfully applied in future dense networks formed...This material is aimed to attract attention to the “incoherent approach for power NOMA-RIS-MIMO transmission in wireless channels”. Such kind of approach might be successfully applied in future dense networks formed by High-Speed Vehicles (HSV networks, etc.). Those scenarios take place in doubly selective communication channels typical for such kind of radio networks. The proposal for the presented hereafter incoherent view (“paradigm”) is based on several basic principles: 1) Shift from the “coherent “ideology”, i.e. rejection of the application of any type of Channel State Information (CSI, CSIT);2) Application of the so-called “invariant” to the communication channel’s features (distortions) modulation technique together with its incoherent demodulation;3) Orthogonal channel decomposition by means of “universal” eigen basis (in the form of Prolate Spheroidal Wave Functions, PSWF) as “artificial trajectories” of wave propagation;4) Chaotic filtering (chaos parameter settings as UE signatures) together with sequential multiuser parallel detection algorithms for users’ identification (classification). It is shown that the proposed approach might provide an effective use of the radio resource and it is relatively simple for implementation.展开更多
The high activity of metallic magnesium and alloys limits its potential in biomedical applications;in recent years,extensive efforts have been devoted to modulating this reactivity.In this work,we present Mg(OH)_(2) a...The high activity of metallic magnesium and alloys limits its potential in biomedical applications;in recent years,extensive efforts have been devoted to modulating this reactivity.In this work,we present Mg(OH)_(2) and TiO_(2)barrier coatings to reduce the degradation of magnesium alloy(Mg-Ca-Zn)surfaces.These coatings were deposited by the anodization method and the spin-coating technique,respectively.The anodized layer was coated with TiO_(2)generated from the hydrolysis of 3%weight of TTIP(Ti[OCH(CH_(3))_(2)]_(4),Titanium(IV)isopropoxide)in 2-Propanol deposited by the spin-coating method.Studying the degradation in Ringer’s solution by electrochemical impedance spectroscopy and OCP revealed a 98%reduction in pittings in uncoated samples after 14 days of immersion.The p H measurements revealed that the TiO_(2)coating reduced the alkalization of the physiological environment,keeping the pH at 6.0 values.In vitro studies of two types of bacteria(E.coli and S.aureus)exhibited zones of inhibition in the agar and activity bactericidal(kill time test).The mechanisms behind the improved degradation resistance and enhanced antibacterial activity are presented and discussed here.Surface modification with Mg(OH)_(2)/TiO_(2)coatings is a promising strategy to control the biodegradation of magnesium implants for bone regeneration.展开更多
针对目前采用经验模态分解(empirical model decomposition,EMD)得到的系列子信号构建的磨机负荷参数软测量模型泛化性能差、难以进行清晰物理解释,以及EMD算法存在的模态混叠等问题,本文提出了基于选择性融合多尺度筒体振动频谱的建模...针对目前采用经验模态分解(empirical model decomposition,EMD)得到的系列子信号构建的磨机负荷参数软测量模型泛化性能差、难以进行清晰物理解释,以及EMD算法存在的模态混叠等问题,本文提出了基于选择性融合多尺度筒体振动频谱的建模方法.首先采用EMD、集合EMD(ensemble EMD,EEMD)、希尔伯特振动分解(Hilbert vibration decomposition,HVD)共3种多组分信号自适应分解算法获得磨机筒体振动多尺度子信号的集合,接着通过相关性分析剔除虚假无关部分,然后再将与原始信号相关性强的那部分多尺度子信号变换至频域,进而更有利于构建这些多尺度频谱与磨机负荷参数间的映射模型,最后通过改进分支定界选择性集成(improved branch and bound based selective ensemble,IBBSEN)算法建立软测量模型,实现对多源多尺度筒体振动频谱的最优选择性信息融合.基于实验球磨机运行数据的仿真实验表明所提方法在模型可解释性和泛化性能上均优于之前研究所提出方法.展开更多
针对过程非线性、基于历史数据构建的离线模型泛化性差以及基于滑动窗口和每样本递推更新的在线建模方法难以均衡建模精度和建模速度等问题,提出了一种在线核偏最小二乘(On-line kernel partial least squares,OLKPLS)建模方法.该方法...针对过程非线性、基于历史数据构建的离线模型泛化性差以及基于滑动窗口和每样本递推更新的在线建模方法难以均衡建模精度和建模速度等问题,提出了一种在线核偏最小二乘(On-line kernel partial least squares,OLKPLS)建模方法.该方法依据新样本与建模样本间的近似线性依靠(Approximate linear dependence,ALD)值和代表工业过程特性漂移幅度的阈值,选择有价值样本更新KPLS模型,并采用合成数据和Benchmark平台数据对该方法进行了仿真验证.针对基于离线历史数据建立的融合多传感器信息的磨机负荷参数集成模型难以适应磨矿过程时变特性的问题,提出了基于OLKPLS和在线自适应加权融合算法的在线集成建模方法,并通过实验球磨机的实际运行数据仿真验证了方法的有效性.展开更多
Acute and chronic colitis affect a huge proportion of the population world-wide.The etiology of colitis cases can be manifold,and diet can significantly affect onset and outcome of colitis.While many forms of acute co...Acute and chronic colitis affect a huge proportion of the population world-wide.The etiology of colitis cases can be manifold,and diet can significantly affect onset and outcome of colitis.While many forms of acute colitis are easily treatable,chronic forms of colitis such as ulcerative colitis and Crohn’s disease(summarized as inflammatory bowel diseases)are multifactorial with poorly understood pathogenesis.Inflammatory bowel diseases are characterized by exacerbated immune responses causing epithelial dysfunction and bacterial translocation.There is no cure and therapies aim at reducing inflammation and restoring intestinal barrier function.Unfortunately,most drugs can have severe side effects.Changes in diet and inclusion of nutritional supplements have been extensively studied in cell culture and animal models,and some supplements have shown promising results in clinical studies.Most of these nutritional supplements including vitamins,fatty acids and phytochemicals reduce oxidative stress and inflammation and have shown beneficial effects during experimental colitis in rodents induced by dextran sulphate sodium or 2,4,6-trinitrobenzene sulfonic acid,which remain the gold standard in pre-clinical colitis research.Here,we summarize the mechanisms through which such nutritional supplements contribute to epithelial barrier stabilization.展开更多
To study the molecular mechanisms involved in the hepatoprotective effects of naringenin (NAR) on carbon tetrachloride (CCl<sub>4</sub>)-induced liver fibrosis. METHODSThirty-two male Wistar rats (120-150 ...To study the molecular mechanisms involved in the hepatoprotective effects of naringenin (NAR) on carbon tetrachloride (CCl<sub>4</sub>)-induced liver fibrosis. METHODSThirty-two male Wistar rats (120-150 g) were randomly divided into four groups: (1) a control group (n = 8) that received 0.7% carboxy methyl-cellulose (NAR vehicle) 1 mL/daily p.o.; (2) a CCl<sub>4</sub> group (n = 8) that received 400 mg of CCl<sub>4</sub>/kg body weight i.p. 3 times a week for 8 wk; (3) a CCl<sub>4</sub> + NAR (n = 8) group that received 400 mg of CCl<sub>4</sub>/kg body weight i.p. 3 times a week for 8 wk and 100 mg of NAR/kg body weight daily for 8 wk p.o.; and (4) an NAR group (n = 8) that received 100 mg of NAR/kg body weight daily for 8 wk p.o. After the experimental period, animals were sacrificed under ketamine and xylazine anesthesia. Liver damage markers such as alanine aminotransferase (ALT), alkaline phosphatase (AP), γ-glutamyl transpeptidase (γ-GTP), reduced glutathione (GSH), glycogen content, lipid peroxidation (LPO) and collagen content were measured. The enzymatic activity of glutathione peroxidase (GPx) was assessed. Liver histopathology was performed utilizing Masson’s trichrome and hematoxylin-eosin stains. Zymography assays for MMP-9 and MMP-2 were carried out. Hepatic TGF-β, α-SMA, CTGF, Col-I, MMP-13, NF-κB, IL-1, IL-10, Smad7, Smad3, pSmad3 and pJNK proteins were detected via western blot. RESULTSNAR administration prevented increases in ALT, AP, γ-GTP, and GPx enzymatic activity; depletion of GSH and glycogen; and increases in LPO and collagen produced by chronic CCl<sub>4</sub> intoxication (P < 0.05). Liver histopathology showed a decrease in collagen deposition when rats received NAR in addition to CCl<sub>4</sub>. Although zymography assays showed that CCl<sub>4</sub> produced an increase in MMP-9 and MMP-2 gelatinase activity; interestingly, NAR administration was associated with normal MMP-9 and MMP-2 activity (P < 0.05). The anti-inflammatory, antinecrotic and antifibrotic effects of NAR may be attributed to its ability to prevent NF-κB activation and the subsequent production of IL-1 and IL-10 (P < 0.05). NAR completely prevented the increase in TGF-β, α-SMA, CTGF, Col-1, and MMP-13 proteins compared with the CCl<sub>4</sub>-treated group (P < 0.05). NAR prevented Smad3 phosphorylation in the linker region by JNK since this flavonoid blocked this kinase (P < 0.05). CONCLUSIONNAR prevents CCl<sub>4</sub> induced liver inflammation, necrosis and fibrosis, due to its antioxidant capacity as a free radical inhibitor and by inhibiting the NF-κB, TGF-β-Smad3 and JNK-Smad3 pathways.展开更多
Carcinogenic process has been proposed to relay on the capacity to induce local tissue damage and proliferative repair. Liver has a great regeneration capacity and currently, most studies point towards the dominant ro...Carcinogenic process has been proposed to relay on the capacity to induce local tissue damage and proliferative repair. Liver has a great regeneration capacity and currently, most studies point towards the dominant role of hepatocytes in regeneration at all levels of liver damage. The most frequent liver cancer is hepatocellular carcinoma(HCC). Historical findings originally led to the idea that the cell of origin of HCC might be a progenitor cell. However, current linage tracing studies put the progenitor hypothesis of HCC origin into question. In agreement with their dominant role in liver regeneration, mature hepatocytes are emerging as the cell of origin of HCC, although, the specific hepatocyte subpopulation of origin is yet to be determined. The relationship between the cancer cell of origin(CCO) and cancer-propagating cells, known as hepatic cancer stem cell(HCSC) is unknown. It has been challenging to identify the definitive phenotypic marker of HCSC, probably due to the existence of different cancer stem cells(CSC) subpopulations with different functions within HCC. There is a dynamic interconversion among different CSCs, and between CSC and non-CSCs. Because of that, CSC-state is currently defined as a description of a highly adaptable and dynamic intrinsic property of tumor cells, instead of a static subpopulation of a tumor. Altered conditions could trigger the gain of stemness, some of them include: EMT-MET, epigenetics, microenvironment and selective stimulus such as chemotherapy. This CSC heterogeneity and dynamism makes them out reach from therapeutic protocols directed to a single target. A further avenue of research in this line will be to uncover mechanisms that trigger this interconversion of cell populations within tumors and target it.展开更多
Due to the environmental policies and economic reasons,the water used in some flotation operations of complex sulfide ores is recirculated,causing the ion concentration of some species to increase over time,affecting ...Due to the environmental policies and economic reasons,the water used in some flotation operations of complex sulfide ores is recirculated,causing the ion concentration of some species to increase over time,affecting the flotation of the minerals of interest.In this work,an experimental and thermodynamic analysis of the synthetic solutions was presented with a high content of calcium and sulfate ions.The study focused on evaluating the use of two aluminum compounds for the precipitation of Ca^(2+)and SO_(4)^(2−)in the form of ettringite.The amorphous aluminum hydroxide was found to be more efficient than the crystalline one,giving rise to 83%calcium and 91%sulfate removal.The XRD analysis of the solids showed the main reaction product of ettringite,accompanied by small amounts of calcite,due to the absorption of atmospheric carbon dioxide.The final solution after the chemical treatment showed residual calcium and sulfate concentrations below 200 mg/L.Finally,the kinetics of calcium removal appeared to correspond to a second order reaction with respect to calcium concentration,with an apparent activation energy of 53.48 kJ/mol,which may suggest that the ettringite precipitation process is governed by the chemical reaction.展开更多
This work deals with the degradation of AZ31 and AZ91 magnesium alloys when they are exposed to three types of physiological media for seven days at 37°C:Ringer's,Hanks\and simulated body fluid(SBF)solutions....This work deals with the degradation of AZ31 and AZ91 magnesium alloys when they are exposed to three types of physiological media for seven days at 37°C:Ringer's,Hanks\and simulated body fluid(SBF)solutions.A combination of immersions tests and surface characterisation methods were employed to evaluate the attack on the surface,and the stability of the formed corrosion product layers for each alloy/electrolyte system.Measurements of the Mg-ion released into the electrolytes were also carried out in order to be correlated with the degradation of the alloys.Electrochemical impedance spectroscopy(EIS)and potentiodynamic polarisation(PDP)techniques were employed to compare the performance of the alloys in these different aggressive electrolytes.According to the obtained results,the Mg-alloys exposed to Hanks'media were the less affected,which fact was attributed to a higher stability of the corrosion products layer formed in this medium,in comparison of those formed in Ringer's and SBF solutions.In add让ion,the corrosion damage was lower for AZ91 than for AZ31 alloy in all environments due to its higher Al content.The mass loss rates calculated from both immersion tests and electrochemical methods followed the same trend for comparative purposes between alloys.展开更多
This work presents a simple method to functionalise the surface of AZ31 magnesium alloy by applying a duplex MgF_(2)/chitosan coating,which improves its corrosion resistance and provides it with some antibacterial per...This work presents a simple method to functionalise the surface of AZ31 magnesium alloy by applying a duplex MgF_(2)/chitosan coating,which improves its corrosion resistance and provides it with some antibacterial performance.First,the effect of three chitosan solutions with different concentrations on the growth of the bacteria Klebsiella pneumoniae in nutritive medium(TSB)was evaluated by absorbance kinetics experiments,where the chitosan solution at 2%(m/V)was selected for the coating preparation.Before coating application,the AZ31 substrate was pretreated with hydrofluoric acid for 48 hours in order to form a MgF_(2)conversion layer.Subsequently,the coating was applied to the pretreated substrate through the dry-casting method.Samples of the alloy in each surface condition(bare,pretreated,and pretreated+coated with chitosan)were exposed to simulated body fluid(SBF)for 21 days at 37°C,with the solution renewed every 24 hours and the wastes stored.The surfaces were characterised by SEM-EDS,and XPS after the immersion tests,whereas the stored solutions were employed to measure the change in the Mg-ions concentration.Electrochemical impedance spectroscopy and potentiodynamic polarisation were performed in each surface condition to compare their corrosion resistance in SBF.The antibacterial activity of the functionalised surfaces was evaluated by the plate counting method and compared with bare samples.All results were correlated and demonstrate that the modified surface of AZ31 achieved a higher corrosion resistance when it was exposed to SBF,as well as a reduction of the bacterial growth during in vitro tests.展开更多
文摘The following material is devoted to the generalization of the chaos modeling to random fields in communication channels and its application on the space-time filtering for the incoherent paradigm;that is the purpose of this research. The approach, presented hereafter, is based on the “Markovian” trend in modeling of random fields, and it is applied for the first time to the chaos field modeling through the well-known concept of the random “treatment” of deterministic dynamic systems, first presented by A. Kolmogorov, M. Born, etc. The material presents the generalized Stratonovich-Kushner Equations (SKE) for the optimum filtering of chaotic models of random fields and its simplified quasi-optimum solutions. In addition to this, the application of the multi-moment algorithms for quasi-optimum solutions is considered and, it is shown, that for scenarios, when the covariation interval of the input random field is less than the distance between the antenna elements, the gain of the space-time algorithms against their “time” analogies is significant. This is the general result presented in the following.
文摘Hepatocellular carcinoma(HCC)is one of the most lethal malignant tumours worldwide.The mortality-to-incidence ratio is up to 91.6%in many countries,representing the third leading cause of cancer-related deaths.Systemic drugs,including the multikinase inhibitors sorafenib and lenvatinib,are first-line drugs used in HCC treatment.Unfortunately,these therapies are ineffective in most cases due to late diagnosis and the development of tumour resistance.Thus,novel pharmacological alternatives are urgently needed.For instance,immune checkpoint inhibitors have provided new approaches targeting cells of the immune system.Furthermore,monoclonal antibodies against programmed cell death-1 have shown benefits in HCC patients.In addition,drug combinations,including first-line treatment and immunotherapy,as well as drug repurposing,are promising novel therapeutic alternatives.Here,we review the current and novel pharmacological approaches to fight HCC.Preclinical studies,as well as approved and ongoing clinical trials for liver cancer treatment,are discussed.The pharmacological opportunities analysed here should lead to significant improvement in HCC therapy.
文摘This material is aimed to attract attention to the “incoherent approach for power NOMA-RIS-MIMO transmission in wireless channels”. Such kind of approach might be successfully applied in future dense networks formed by High-Speed Vehicles (HSV networks, etc.). Those scenarios take place in doubly selective communication channels typical for such kind of radio networks. The proposal for the presented hereafter incoherent view (“paradigm”) is based on several basic principles: 1) Shift from the “coherent “ideology”, i.e. rejection of the application of any type of Channel State Information (CSI, CSIT);2) Application of the so-called “invariant” to the communication channel’s features (distortions) modulation technique together with its incoherent demodulation;3) Orthogonal channel decomposition by means of “universal” eigen basis (in the form of Prolate Spheroidal Wave Functions, PSWF) as “artificial trajectories” of wave propagation;4) Chaotic filtering (chaos parameter settings as UE signatures) together with sequential multiuser parallel detection algorithms for users’ identification (classification). It is shown that the proposed approach might provide an effective use of the radio resource and it is relatively simple for implementation.
基金financed by the FOMIX-Yucatán 2008-108160,CONACYT LAB-2009-01-123913,292692,294643,188345,and 204822 projectsthe financial support received from CONACYT。
文摘The high activity of metallic magnesium and alloys limits its potential in biomedical applications;in recent years,extensive efforts have been devoted to modulating this reactivity.In this work,we present Mg(OH)_(2) and TiO_(2)barrier coatings to reduce the degradation of magnesium alloy(Mg-Ca-Zn)surfaces.These coatings were deposited by the anodization method and the spin-coating technique,respectively.The anodized layer was coated with TiO_(2)generated from the hydrolysis of 3%weight of TTIP(Ti[OCH(CH_(3))_(2)]_(4),Titanium(IV)isopropoxide)in 2-Propanol deposited by the spin-coating method.Studying the degradation in Ringer’s solution by electrochemical impedance spectroscopy and OCP revealed a 98%reduction in pittings in uncoated samples after 14 days of immersion.The p H measurements revealed that the TiO_(2)coating reduced the alkalization of the physiological environment,keeping the pH at 6.0 values.In vitro studies of two types of bacteria(E.coli and S.aureus)exhibited zones of inhibition in the agar and activity bactericidal(kill time test).The mechanisms behind the improved degradation resistance and enhanced antibacterial activity are presented and discussed here.Surface modification with Mg(OH)_(2)/TiO_(2)coatings is a promising strategy to control the biodegradation of magnesium implants for bone regeneration.
文摘针对目前采用经验模态分解(empirical model decomposition,EMD)得到的系列子信号构建的磨机负荷参数软测量模型泛化性能差、难以进行清晰物理解释,以及EMD算法存在的模态混叠等问题,本文提出了基于选择性融合多尺度筒体振动频谱的建模方法.首先采用EMD、集合EMD(ensemble EMD,EEMD)、希尔伯特振动分解(Hilbert vibration decomposition,HVD)共3种多组分信号自适应分解算法获得磨机筒体振动多尺度子信号的集合,接着通过相关性分析剔除虚假无关部分,然后再将与原始信号相关性强的那部分多尺度子信号变换至频域,进而更有利于构建这些多尺度频谱与磨机负荷参数间的映射模型,最后通过改进分支定界选择性集成(improved branch and bound based selective ensemble,IBBSEN)算法建立软测量模型,实现对多源多尺度筒体振动频谱的最优选择性信息融合.基于实验球磨机运行数据的仿真实验表明所提方法在模型可解释性和泛化性能上均优于之前研究所提出方法.
文摘针对过程非线性、基于历史数据构建的离线模型泛化性差以及基于滑动窗口和每样本递推更新的在线建模方法难以均衡建模精度和建模速度等问题,提出了一种在线核偏最小二乘(On-line kernel partial least squares,OLKPLS)建模方法.该方法依据新样本与建模样本间的近似线性依靠(Approximate linear dependence,ALD)值和代表工业过程特性漂移幅度的阈值,选择有价值样本更新KPLS模型,并采用合成数据和Benchmark平台数据对该方法进行了仿真验证.针对基于离线历史数据建立的融合多传感器信息的磨机负荷参数集成模型难以适应磨矿过程时变特性的问题,提出了基于OLKPLS和在线自适应加权融合算法的在线集成建模方法,并通过实验球磨机的实际运行数据仿真验证了方法的有效性.
基金funded by the fund SEP-Cinvestav (Project 108)by Conacyt (284292)the Royal Society (NAF/R1/180017)
文摘Acute and chronic colitis affect a huge proportion of the population world-wide.The etiology of colitis cases can be manifold,and diet can significantly affect onset and outcome of colitis.While many forms of acute colitis are easily treatable,chronic forms of colitis such as ulcerative colitis and Crohn’s disease(summarized as inflammatory bowel diseases)are multifactorial with poorly understood pathogenesis.Inflammatory bowel diseases are characterized by exacerbated immune responses causing epithelial dysfunction and bacterial translocation.There is no cure and therapies aim at reducing inflammation and restoring intestinal barrier function.Unfortunately,most drugs can have severe side effects.Changes in diet and inclusion of nutritional supplements have been extensively studied in cell culture and animal models,and some supplements have shown promising results in clinical studies.Most of these nutritional supplements including vitamins,fatty acids and phytochemicals reduce oxidative stress and inflammation and have shown beneficial effects during experimental colitis in rodents induced by dextran sulphate sodium or 2,4,6-trinitrobenzene sulfonic acid,which remain the gold standard in pre-clinical colitis research.Here,we summarize the mechanisms through which such nutritional supplements contribute to epithelial barrier stabilization.
基金Supported by National Council of Science and Technology(Conacyt)of Mexico,No.253037 to Muriel P,and No.239516 to Segovia JFellowship No.358378 Hernández-Aquino E to from Conacytsupported by a grant of PRODEP(UABC-PTC-464)Mexico
文摘To study the molecular mechanisms involved in the hepatoprotective effects of naringenin (NAR) on carbon tetrachloride (CCl<sub>4</sub>)-induced liver fibrosis. METHODSThirty-two male Wistar rats (120-150 g) were randomly divided into four groups: (1) a control group (n = 8) that received 0.7% carboxy methyl-cellulose (NAR vehicle) 1 mL/daily p.o.; (2) a CCl<sub>4</sub> group (n = 8) that received 400 mg of CCl<sub>4</sub>/kg body weight i.p. 3 times a week for 8 wk; (3) a CCl<sub>4</sub> + NAR (n = 8) group that received 400 mg of CCl<sub>4</sub>/kg body weight i.p. 3 times a week for 8 wk and 100 mg of NAR/kg body weight daily for 8 wk p.o.; and (4) an NAR group (n = 8) that received 100 mg of NAR/kg body weight daily for 8 wk p.o. After the experimental period, animals were sacrificed under ketamine and xylazine anesthesia. Liver damage markers such as alanine aminotransferase (ALT), alkaline phosphatase (AP), γ-glutamyl transpeptidase (γ-GTP), reduced glutathione (GSH), glycogen content, lipid peroxidation (LPO) and collagen content were measured. The enzymatic activity of glutathione peroxidase (GPx) was assessed. Liver histopathology was performed utilizing Masson’s trichrome and hematoxylin-eosin stains. Zymography assays for MMP-9 and MMP-2 were carried out. Hepatic TGF-β, α-SMA, CTGF, Col-I, MMP-13, NF-κB, IL-1, IL-10, Smad7, Smad3, pSmad3 and pJNK proteins were detected via western blot. RESULTSNAR administration prevented increases in ALT, AP, γ-GTP, and GPx enzymatic activity; depletion of GSH and glycogen; and increases in LPO and collagen produced by chronic CCl<sub>4</sub> intoxication (P < 0.05). Liver histopathology showed a decrease in collagen deposition when rats received NAR in addition to CCl<sub>4</sub>. Although zymography assays showed that CCl<sub>4</sub> produced an increase in MMP-9 and MMP-2 gelatinase activity; interestingly, NAR administration was associated with normal MMP-9 and MMP-2 activity (P < 0.05). The anti-inflammatory, antinecrotic and antifibrotic effects of NAR may be attributed to its ability to prevent NF-κB activation and the subsequent production of IL-1 and IL-10 (P < 0.05). NAR completely prevented the increase in TGF-β, α-SMA, CTGF, Col-1, and MMP-13 proteins compared with the CCl<sub>4</sub>-treated group (P < 0.05). NAR prevented Smad3 phosphorylation in the linker region by JNK since this flavonoid blocked this kinase (P < 0.05). CONCLUSIONNAR prevents CCl<sub>4</sub> induced liver inflammation, necrosis and fibrosis, due to its antioxidant capacity as a free radical inhibitor and by inhibiting the NF-κB, TGF-β-Smad3 and JNK-Smad3 pathways.
文摘Carcinogenic process has been proposed to relay on the capacity to induce local tissue damage and proliferative repair. Liver has a great regeneration capacity and currently, most studies point towards the dominant role of hepatocytes in regeneration at all levels of liver damage. The most frequent liver cancer is hepatocellular carcinoma(HCC). Historical findings originally led to the idea that the cell of origin of HCC might be a progenitor cell. However, current linage tracing studies put the progenitor hypothesis of HCC origin into question. In agreement with their dominant role in liver regeneration, mature hepatocytes are emerging as the cell of origin of HCC, although, the specific hepatocyte subpopulation of origin is yet to be determined. The relationship between the cancer cell of origin(CCO) and cancer-propagating cells, known as hepatic cancer stem cell(HCSC) is unknown. It has been challenging to identify the definitive phenotypic marker of HCSC, probably due to the existence of different cancer stem cells(CSC) subpopulations with different functions within HCC. There is a dynamic interconversion among different CSCs, and between CSC and non-CSCs. Because of that, CSC-state is currently defined as a description of a highly adaptable and dynamic intrinsic property of tumor cells, instead of a static subpopulation of a tumor. Altered conditions could trigger the gain of stemness, some of them include: EMT-MET, epigenetics, microenvironment and selective stimulus such as chemotherapy. This CSC heterogeneity and dynamism makes them out reach from therapeutic protocols directed to a single target. A further avenue of research in this line will be to uncover mechanisms that trigger this interconversion of cell populations within tumors and target it.
文摘Due to the environmental policies and economic reasons,the water used in some flotation operations of complex sulfide ores is recirculated,causing the ion concentration of some species to increase over time,affecting the flotation of the minerals of interest.In this work,an experimental and thermodynamic analysis of the synthetic solutions was presented with a high content of calcium and sulfate ions.The study focused on evaluating the use of two aluminum compounds for the precipitation of Ca^(2+)and SO_(4)^(2−)in the form of ettringite.The amorphous aluminum hydroxide was found to be more efficient than the crystalline one,giving rise to 83%calcium and 91%sulfate removal.The XRD analysis of the solids showed the main reaction product of ettringite,accompanied by small amounts of calcite,due to the absorption of atmospheric carbon dioxide.The final solution after the chemical treatment showed residual calcium and sulfate concentrations below 200 mg/L.Finally,the kinetics of calcium removal appeared to correspond to a second order reaction with respect to calcium concentration,with an apparent activation energy of 53.48 kJ/mol,which may suggest that the ettringite precipitation process is governed by the chemical reaction.
文摘This work deals with the degradation of AZ31 and AZ91 magnesium alloys when they are exposed to three types of physiological media for seven days at 37°C:Ringer's,Hanks\and simulated body fluid(SBF)solutions.A combination of immersions tests and surface characterisation methods were employed to evaluate the attack on the surface,and the stability of the formed corrosion product layers for each alloy/electrolyte system.Measurements of the Mg-ion released into the electrolytes were also carried out in order to be correlated with the degradation of the alloys.Electrochemical impedance spectroscopy(EIS)and potentiodynamic polarisation(PDP)techniques were employed to compare the performance of the alloys in these different aggressive electrolytes.According to the obtained results,the Mg-alloys exposed to Hanks'media were the less affected,which fact was attributed to a higher stability of the corrosion products layer formed in this medium,in comparison of those formed in Ringer's and SBF solutions.In add让ion,the corrosion damage was lower for AZ91 than for AZ31 alloy in all environments due to its higher Al content.The mass loss rates calculated from both immersion tests and electrochemical methods followed the same trend for comparative purposes between alloys.
基金CONACYT for his scholarship as a Ph.D.student at CINVESTAV-IPN
文摘This work presents a simple method to functionalise the surface of AZ31 magnesium alloy by applying a duplex MgF_(2)/chitosan coating,which improves its corrosion resistance and provides it with some antibacterial performance.First,the effect of three chitosan solutions with different concentrations on the growth of the bacteria Klebsiella pneumoniae in nutritive medium(TSB)was evaluated by absorbance kinetics experiments,where the chitosan solution at 2%(m/V)was selected for the coating preparation.Before coating application,the AZ31 substrate was pretreated with hydrofluoric acid for 48 hours in order to form a MgF_(2)conversion layer.Subsequently,the coating was applied to the pretreated substrate through the dry-casting method.Samples of the alloy in each surface condition(bare,pretreated,and pretreated+coated with chitosan)were exposed to simulated body fluid(SBF)for 21 days at 37°C,with the solution renewed every 24 hours and the wastes stored.The surfaces were characterised by SEM-EDS,and XPS after the immersion tests,whereas the stored solutions were employed to measure the change in the Mg-ions concentration.Electrochemical impedance spectroscopy and potentiodynamic polarisation were performed in each surface condition to compare their corrosion resistance in SBF.The antibacterial activity of the functionalised surfaces was evaluated by the plate counting method and compared with bare samples.All results were correlated and demonstrate that the modified surface of AZ31 achieved a higher corrosion resistance when it was exposed to SBF,as well as a reduction of the bacterial growth during in vitro tests.
