Search

In this paper, a mathematical ordinary differential tumor-immune model is proposed based on an immune checkpoint inhibitor, which is an innovative method for tumor immunotherapies. Two important factors in tumor-immune response are the programmed cell death protein 1 (PD-1) and its ligand PD-L1. The model consists of three populations: tumor cells, activated T cells and anti-PD-1. By analyzing the dynamics of the model, it is found that there is always a unique tumor-free equilibrium and at most two tumor interior equilibria. The nonexistence of nontrivial positive periodic orbits is established by using the new Dulac function, and then a global dynamics of the model is obtained. The conclusions of our analysis show that increasing the possibility of T cells killing tumor cells (p), early detection of tumor cells, or the use of PD-1 inhibitors to activate T cells are effective in eliminating tumor cells. [ABSTRACT FROM AUTHOR]

• D. vulgaris induced ferrihydrite transformation via the direct reduction and S2−-driven processes. • The presence of SO 4 2− altered the mineralogical transformation of ferrihydrite. • The formation of magnetite and mackinawite enhanced the stability of As in solids. • High SO 4 2− loadings (SO 4 2−/Fe = 1.5) resulted in the substantial mobilization of As into the solution. Sulfate-reducing bacteria play an important role in the geochemistry of iron (oxyhydr)oxide and arsenic (As) in natural environments; however, the associated reaction processes are yet to be fully understood. In this study, batch experiments coupled with geochemical, spectroscopic, microscopic, and thermodynamic analyses were conducted to investigate the dynamic coupling of ferrihydrite transformation and the associated As desorption/redistribution mediated by Desulfovibrio vulgaris (D. vulgaris). The results indicated that D. vulgaris could induce ferrihydrite transformation via S2−-driven and direct reduction processes. In the absence of SO 4 2−, D. vulgaris directly reduced ferrihydrite, and As desorption and re-sorption occurred simultaneously during the partial transformation of ferrihydrite to magnetite. The increase in SO 4 2− loading promoted the S2−-driven reduction of ferrihydrite and accelerated the subsequent mineralogical transformation. In the low and medium SO 4 2− treatments, ferrihydrite was completely transformed to a mixture of magnetite and mackinawite, which increased the fraction of As in the residual phase and stabilized As. In the high SO 4 2− treatment, although the replacement of ferrihydrite by only mackinawite also increased the fraction of As in the residual phase, 22.1% of the total As was released into the solution due to the poor adsorption affinity of As to mackinawite and the conversion of As5+ to As3+. The mechanisms of ferrihydrite reduction, mineralogy transformation, and As mobilization and redistribution mediated by sulfate-reducing bacteria are closely related to the surrounding SO 4 2− loadings. These results advance our understanding of the biogeochemical behavior of Fe, S, and As, and are helpful for the risk assessment and remediation of As contamination. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A data-based model is established to describe cross-scale iron bioreduction rates. • Sensitive analysis is used to provide insights to the data-based 'black box' model. • The model is validated using new data from the experiments in this study. Bioreduction rates of iron (Fe) oxides are a key variable for predicting the fate and transport of Fe and contaminants in subsurface environments. Such rates, however, vary significantly at different spatial scales, and change in orders of magnitude even within the same scale. This study first collected and consistently processed the data of Fe oxide bioreduction rates from literature, which were then used to train a machine learning (ML) model that resulted in a well-fitted relationship between the cross-scale bioreduction rates and common influencing factors including electron donor concentrations, electron numbers, Fe concentrations, cell numbers, and reaction Gibbs free energy. Sensitivity analysis was performed to provide insights into the relative role of the influencing factors and how they affect the rates. The result indicated that their effects were generally consistent with saturation type models. New experiments of iron oxide bioreduction were performed to validate the ML-based cross-scale model. The result showed that ML-based model well predicted the experimental results, indicating the effectiveness of the model. The result has a strong implication for developing the models of cross-scale reaction rates of iron oxide bioreduction in environmental systems and for predicting the fate and transport of iron and contaminants. [ABSTRACT FROM AUTHOR]

Background: Observing and studying clinical efficacy and safety of apatinib mesylate tablet in the treatment of advanced malignant melanoma (MM). Methods: Retrospectively analyzing the clinical data of 22 patients with metastatic MM who had failed conventional chemotherapy from June 2016 to January 2018. All patients took 500 mg of apatinib mesylate tablets per day. The efficacy should be evaluated according to RECIST 1.1 criteria. Adverse events (AEs) should be graded according to NCI-CTCAE 4.0. Results: There were two cases of partial remission (PR), 11 of stable disease (SD) and nine of progressive disease (PD) in the 22 patients with advanced MM, where the objective remission rate (ORR) was 9.1% and the disease control rate (DCR) was 59.1%. The median progression-free survival (PFS) was 7.5 months, and the 6-month progression-free survival rate (PFR) was 54.7%. Six patients died and the overall survival (OS) was not reached. AEs were controllable and all were in Grade 1–3. Conclusion: Apatinib mesylate tablets have a certain curative effect on patients with malignant melanomas of Stage IV who failed conventional chemotherapy. Apatinib mesylate tablets at a daily dose of 500 mg are well tolerated by most patients. [ABSTRACT FROM AUTHOR]

Although PO 4 3- is commonly found in association with iron (oxyhydr)oxide, the effect of PO 4 3- on ferrihydrite reduction, mineralogical transformation, and associated As behavior in sulfate-reducing bacteria (SRB)-rich environments remains unclear. In this study, batch experiments, together with geochemical, mineralogical, and biological analyses, were conducted to elucidate these processes. The results showed that SRB can reduce ferrihydrite via direct and indirect processes, and PO 4 3- promoted ferrihydrite reduction by supporting SRB growth at low and medium PO 4 3- loadings. However, at high loadings, PO 4 3- stabilized the ferrihydrite. PO 4 3- shifted the transformation of ferrihydrite from magnetite and mackinawite to vivianite, which scavenges As effectively by incorporating As into its particle. In systems with 0.5 mM SO 4 2-, PO 4 3- exerted a weak effect on As mobilization. However, in systems with 10 mM SO 4 2-, substantial amounts of As were released into the solution, and PO 4 3- impacted As behavior strongly. Low PO 4 3- loadings increased the mobilization of As because of the competitive adsorption of PO 4 3- on mackinawite. Medium and high PO 4 3- loadings were beneficial for As immobilization because of the substitution of mackinawite by vivianite. These findings have important implications for understanding the biogeochemistry of iron (oxyhydr)oxide and As behavior in SRB-containing sediments. [Display omitted] • High SO 4 2- (10 mM) resulted in a substantial release of As into the solution. • PO 4 3- complexly affected ferrihydrite reduction and the associated As behavior. • High PO 4 3- loading benefited As immobilization, whereas low PO 4 3- loading did not. • Vivianite scavenged As effectively via incorporating As into its particles. [ABSTRACT FROM AUTHOR]

A periodic pulse differential equation model of tumor immunotherapy is established by considering the periodic and transient behavior of infusing immune cells. Using comparison theorem and Floquet multiplier theory of the impulsive differential equation, the boundedness of the model solution, the existence and stability of the free-tumor periodic solution are given. Furthermore, the persistence of the system is analyzed. Numerical simulations are carried to confirm the main theorems. [ABSTRACT FROM AUTHOR]

Iron (Fe) oxides and fulvic acid (FA) are the key components affecting the fate of cadmium (Cd) in soil. The presence of FA influences Fe mineral transformation, and FA may complicate phase transformation and dynamic behavior of Cd. How varying Fe minerals and FA affect Cd immobilization during the ferrihydrite transformation induced by various Fe(II) concentrations, however, is still lack of quantitative understanding. In this study, we built a model for Cd species quantification during phase transformation based on mechanistic insights obtained from batch experiments. Spectroscopic analysis showed that Fe(II) concentrations affected secondary Fe minerals formation under the condition of co-existence of Cd and FA, and ultimately changed the distribution of Cd and FA. Microscopic analysis revealed that besides surface adsorption, part of Cd was sequestrated by magnetite, whereas FA was able to diffuse into lepidocrocite defects. The model revealed that adsorbed Cd was mainly controlled by FA and ferrihydrite, and direct complexation of Cd by FA had a strong impact on the continuous change in Cd at lower Fe(II) concentration. The results contribute to an in-depth understanding of the mobility of Cd in the environment and provide a method for quantifying the dynamic behavior of heavy metals in multi-reactant systems. [Display omitted] • High concentration of Fe(II) is beneficial to the Cd incorporation. • Cd distribution was quantitatively assessed by an integrated surface complexation model. • Adsorbed Cd was mainly controlled by fulvic acid and ferrihydrite. • Quantitative mode can assess the roles of each reactant for Cd adsorption. [ABSTRACT FROM AUTHOR]

In this paper, a reaction-diffusion model describing temporal development of tumor tissue, normal tissue and excess H+ ion concentration is considered. Based on a combination of perturbation methods, the Fredholm theory and Banach fixed point theorem, we theoretically justify the existence of the traveling wave solution for this model. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we consider a HIV infection model with CTL-response delay and analyze the effect of time delay on stability of equilibria. We obtain the global stability of the infection-free equilibrium and give sufficient conditions for the local stability of the CTL-absent equilibrium and CTL-present equilibrium. By choosing the CTL-response delay as a bifurcation parameter, we prove that the CTL-present equilibrium is locally asymptotically stable in a range of delays and a Hopf bifurcation occurs as crosses a critical value. Numerical simulations are given to support the theoretical results. [Copyright &y& Elsevier]

Abstract: In this paper, we consider a tri-neuron network model with discrete and distributed delays. After discussing the distributions of the roots of the characteristic equation local stability analysis of the steady-state solution leads to, we analyze the stability of network models with instantaneous feedback and neural interaction history, delayed neural feedback and no neural interaction history and delayed neural feedback and neural interaction history; we give sufficient conditions for the linear stability of the equilibrium solution; we also show that a Hopf bifurcation can occur when the delays take certain critical values; and we further prove that there is a positive integer K such that there are K switches from stability to instability and back to stability. Numerical simulations are finally performed to illustrate the obtained results. [Copyright &y& Elsevier]

Abstract: We derive a class of delay difference equations with piecewise constant nonlinearity. The convergence of solutions and the existence of asymptotically stable periodic solutions are investigated, for such a class of difference equations. [Copyright &y& Elsevier]

This paper is concerned with a delay differential system with piecewise constant nonlinearity. Such a differential system can be regarded as a model of two-neuron artificial neural network with delayed feedback. Some interesting results are obtained for the convergence and periodicity of solutions of the system. [Copyright &y& Elsevier]

Abstract: In this paper, we consider a class of delay difference systems with piecewise constant nonlinearity, which includes the discrete version of an artificial neural network model of two neurons described by differential equations with piecewise constant arguments. Some interesting results are obtained for the periodicity and convergence of solutions of the systems. [Copyright &y& Elsevier]

Objective: Population-based epidemiological data on left common iliac vein (LCIV) compression is scarce. This study aimed to investigate the prevalence of LCIV compression in an asymptomatic population and patients with left iliofemoral deep vein thrombosis (IF-DVT). Materials and Methods: Nonprobability sampling method was used in this multicenter cross-sectional study. The minimum diameter of LCIV and right common iliac vein minimum were measured. The percentage of LCIV compression (LCIV-CP) was calculated. Compression severity (CS) was classified as mild (CP ≤ 50%), moderate (50% < CP ≤ 70%), and severe (CP > 70%). Results: In all, 896 subjects constituted the asymptomatic population and 93 patients constituted the IF-DVT population. In the asymptomatic population, LCIV-CP ranged from 1.1% to 89.9% (mean 44.0%), and people with mild, moderate, and severe CS accounted for 62.3%, 28.2%, and 9.5%, respectively. In the IF-DVT population, the mean LCIV-CP was 71.1% (range 42.2%–95.2%), and patients with severe CS accounted for 75.3%. Gender and age differences in LCIV-CP and CS distribution were observed in the asymptomatic population. Females, the young- and middle-aged group had higher LCIV-CPs. In the population with moderate-severe CS, the middle-aged group accounted for a larger proportion. Middle-aged females comprised the highest percentage of patients with moderate or severe CS. Sex and age affected the LCIV-CP and CS distribution. No gender and age differences were observed in the IF-DVT population. Conclusions: LCIV compression is common in population. Middle-aged females are the predominant population with moderate-severe compression. Overlapping of LCIV-CP in the asymptomatic and IF-DVT population is significant and other risk factors should be integrated into the consideration when assessing the risk of IF-DVT secondary to LCIV compression. [ABSTRACT FROM AUTHOR]

Salidroside (SAL), an antioxidant derived from Rhodiola rosea, exerts neuroprotective effects in cerebral ischemia/reperfusion (I/R) injury; however, the mechanisms have not been fully elucidated. The present study established a rat model of middle cerebral artery occlusion/reperfusion (MCAO/R) and a cellular model of oxygen–glucose deprivation/reoxygenation (OGD/R) to explore the roles and mechanisms of SAL in cerebral I/R injury. The rat model of MCAO/R was established and rats were treated with different doses of SAL. The Zea-Longa scoring system and 2,3,5-triphenyltetrazolium chloride (TTC) staining showed that SAL reduced neurological deficit scores and cerebral infarct volumes in MCAO/R rats. The results of Morris water maze (MWM) test showed that SAL reduced memory impairment in MCAO/R rats. In addition, SAL significantly reduced oxidative stress and suppressed inflammatory response. Next, the OGD/R model was established with PC12 cells and treated with SAL. The results of flow cytometry and 3-(4, 5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assays showed that SAL reduced apoptosis, enhanced cell viability and protected neuronal cells from damage by decreasing lactate dehydrogenase (LDH) activity. SAL increased the expression of TSC complex subunit 2 (TSC2), and activated the 5′-AMP-activated protein kinase (AMPK) and inhibited the mammalian target of rapamycin (mTOR) signaling pathways. It was verified that SAL alleviated cerebral I/R injury by regulating the AMPK/TSC2/mTOR pathway to induce autophagy. In conclusion, SAL reduces the inflammatory response and oxidative stress in a concentration-dependent manner, and protects against cerebral I/R injury by modulating TSC2-induced autophagy. These findings suggest SAL may prove to be a potential therapeutic agent for ischemic stroke. [ABSTRACT FROM AUTHOR]

Abstract: The effect of amount of flour in the pre-fermented form (10%, 20%, and 30% flour in the pre-fermented form), fermentation time (12, 24, and 36h), and amount of yeast (0.5%, 1.0%, and 1.5%) on acidity, specific volume, and crumb texture of Chinese Northern-style sourdough steamed breads were studied. Volatile compounds of the sourdough and non-sourdough steamed breads were also determined. The preferments were produced from spontaneous fermentation using all purpose (APF) and whole wheat flours (WWF). Specific volume was the highest at 20% preferment for APF sourdough steamed bread (ASSB) and 30% preferment for WWF sourdough steamed bread (WSSB). The softest texture was obtained with 20% preferment while at 30% preferment there was excessive gluten weakening due to high acidification. A total of 89 volatile compounds were identified in steamed breads with ethanol and 3-methyl-1-butanol being the most abundant compounds. [Copyright &y& Elsevier]

This paper gives new conditions ensuring global asymptotic stability and global exponential stability for cellular neural networks with constant delay and variable delay, respectively. These conditions are derived by using the essence of piecewise linearity of the output function of cellular neural networks and by constructing Lyapunov functions and functionals. Furthermore, these conditions are significantly weaker than those given in existing literature. [Copyright &y& Elsevier]

Circular RNAs (circRNAs) comprise a novel class of widespread non-coding RNAs that may regulate gene expression in eukaryotes. However, the characterization and function of circRNAs in human cancer remain elusive. Here we identified at least 5500 distinct circRNA candidates and a series of circRNAs that are differentially expressed in gastric cancer (GC) tissues compared with matched normal tissues. We further characterized one circRNA derived from the PVT1 gene and termed it as circPVT1. The expression of circPVT1 is often upregulated in GC tissues due to the amplification of its genomic locus. circPVT1 may promote cell proliferation by acting as a sponge for members of the miR-125 family. The level of circPVT1 was observed as an independent prognostic marker for overall survival and disease-free survival of patients with GC. Our findings suggest that circPVT1 is a novel proliferative factor and prognostic marker in GC. [ABSTRACT FROM AUTHOR]

Background and Objectives: To compare the effect on survival of anatomic resection (AR) versus nonanatomic resection (NAR) in patients with hepatocellular carcinoma (HCC) from all published comparative studies in the literature. Methods: Databases, including Pubmed, Embase, the Cochrane Library, Ovid, and Web of Science, were searched to identify studies comparing AR with NAR for HCC. In this meta-analysis, primary end points were the overall survival and disease-free survival; the secondary end point was local recurrence rate. The meta-analysis was performed by use of RevMan 4.2. Results: Nine comparative studies comprising 1,503 patients (833 AR and 670 NAR) were identified. In the combined results, disease-free survival was significantly higher in the AR group than in the NAR group (OR 1.78, 95% CI 1.22-2.59, P = 0.003; heterogeneity P = 0.08). Overall survival (OR 1.31, 95% CI 0.92-1.85, P = 0.13; heterogeneity P = 0.04) did not suggest any significant difference between AR and NAR. No statistically significant difference was found for local recurrence rate between the two resection methods (OR 0.55, 95% CI 0.25-1.23, P = 0.15; heterogeneity P = 0.010). Conclusions: Anatomic resection is associated with better disease-free survival than nonanatomic resection. Because heterogeneity was detected, caution is needed in interpretation of the results. Better designed, adequately powered studies are required to address this issue. [ABSTRACT FROM AUTHOR]