Materials both Tough and Soft Ping Gong, Jian
Science (American Association for the Advancement of Science),
04/2014, Letnik:
344, Številka:
6180
Journal Article
Recenzirano
Tough elastomers are created by adapting an approach previously used for hydrogels.
Also see Report by
Ducrot
et al.
Hydrogels and elastomers are soft materials that have similar network structures ...but very different affinities to water. Consisting mostly of water, hydrogels resemble biological soft tissues and have great potential for use in biomedical applications; they tend to be very brittle, like fragile jellies. Elastomers are formed of nonhydrated polymer networks and are widely used as load-dispersing and shock-absorbing materials. They are stretchable but break easily along a notch. On page 186 of this issue, Ducrot
et al.
(
1
) show that the toughness of elastomers can be improved substantially by combining two different network materials, an approach previously applied to hydrogels.
Purpose
Macrophages play critical roles in inflammation and wound healing and can be divided into two subtypes: classically activated (M1) and alternatively activated (M2) macrophages. Macrophages ...also play important roles in regulating iron homeostasis, and intracellular iron accumulation induces M1‐type macrophage polarization which provides a potential approach to tumor immunotherapy through M2 tumor‐associated macrophage repolarization. However, the mechanisms underlying iron‐induced M1 polarization remain unclear.
Methods
Western blotting, qRT‐PCR, and flow cytometry were used to detect the polarization indexes in RAW 264.7 murine macrophages treated with iron, and Western bloting and qRT‐PCR were used to detect p21 expression. The compound 2,7‐dichlorofluorescein diacetate was used to measure reactive oxygen species (ROS) levels in macrophages after iron or N‐acetyl‐l‐cysteine (NAC) treatment. The p300/CREB‐binding protein (CBP) inhibitor C646 was used to inhibit p53 acetylation, and Western bloting, qRT‐PCR, and immunofluorescence were used to detect p53 expression and acetylation. BALB/c mice were subcutaneously injected with H22 hepatoma cells, and macrophage polarization status was investigated after tail intravenous injection of iron. Immunohistochemical staining was used to evaluate the protein expression of cluster of differentiation 86 (CD86) and EGF‐like module‐containing mucin‐like hormone receptor‐like 1 (F4/80) in the subcutaneous tumors.
Results
Iron overload induced M1 polarization by increasing ROS production and inducing p53 acetylation in RAW cells, and reduction in ROS levels by NAC repressed M1 polarization and p53 acetylation. Inhibition of acetyl‐p53 by a p300/CBP inhibitor prevented M1 polarization and inhibited p21 expression. These results showed that high ROS levels induced by iron overload polarized macrophages to the M1 subtype by enhancing p300/CBP acetyltransferase activity and promoting p53 acetylation.
Iron overload increases ROS production and enhances the activity of p300/CBP acetyltransferase, thus inducing p53 acetylation to polarize proinflammation macrophage phenotype.
Underwater adhesives are in high demand in both commercial and industrial sectors. Compared with adhesives used in dry (air) environments, adhesives used for wet or submerged surfaces in aqueous ...environments have specific challenges in development and performance. In this review, focus is on adhesives demonstrating macroscopic adhesion to wet/underwater substrates. The current strategies are first introduced for different types of underwater adhesives, and then an overview is provided of the development and performance of underwater adhesives based on different mechanisms and strategies. Finally, the possible research directions and prospects of underwater adhesives are discussed.
Underwater adhesives are in high demand from medical to ocean technology. Key specific challenges are discussed to achieve underwater adhesion, and then an overview of strategies of the existing research and the performances of underwater adhesives achieved is presented. Finally, the possible solutions for the challenges, along with future research directions are discussed.
Whether ultra‐processed food consumption is associated with the risk of pancreatic cancer has not been determined. We performed a prospective study to fill this gap. A population‐based cohort of 98 ...265 American adults was identified from the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Ultra‐processed foods were defined by the NOVA classification. Cox regression was used to estimate hazard ratios (HRs) for pancreatic cancer incidence. Subgroup analysis was performed to identify the potential effect modifiers. During a mean follow‐up of 8.86 years, 387 pancreatic cancer cases occurred. High consumption of ultra‐processed foods was found to be associated with an increased risk of pancreatic cancer (fully adjusted HRquartile 4 vs 1:1.49; 95% confidence interval CI: 1.07‐2.07; Ptrend = .021) in a linear dose‐response manner (Pnonlinearity = .075). Subgroup analysis further found that the positive association of ultra‐processed food consumption with the risk of pancreatic cancer was more pronounced in subjects aged <65 years (HRquartile 4 vs 1:2.17; 95% CI: 1.14‐4.15) than in those aged ≥65 years (HRquartile 4 vs 1:1.32; 95% CI: 0.88‐1.94), though the interaction test failed to achieve the statistical significance (Pinteraction = .061). These findings suggest that reducing ultra‐processed food consumption may be beneficial in decreasing pancreatic cancer incidence.
What's new?
“Ultra‐processed” foods, industrially formulated products consisting of ingredients extracted from foods, but no intact foods, now make up as much as 58.5% of Americans' daily calorie intake. Think frozen meals, hot dogs and packaged snacks. Here, the authors investigate the relationship between ultra‐processed foods and pancreatic cancer in a cohort of 98 265 American adults. High consumption of ultra‐processed foods was associated with increased risk of pancreatic cancer, and the association was more pronounced for those under age 65.
Chronic inflammation plays an important role in primary liver cancer (PLC) etiology and can be influenced by dietary habits. No prospective study has investigated the association of dietary ...inflammatory index (DII) with PLC incidence and mortality. Therefore, we used prospective data from the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial to fill this gap. The DII was calculated from a validated 137‐item food frequency questionnaire in a cohort of 103,902 individuals. Cox regression was used to estimate hazard ratios (HRs) for PLC incidence, and competing risk regression was used to estimate subdistribution HRs (SHRs) for PLC mortality. Restricted cubic spline regression was employed to identify the potential dose–response pattern. A total of 120 PLC cases and 102 PLC deaths were observed during follow‐up. Higher DII scores from food and supplement were found to be associated with higher risks of developing PLC (HRTertile 3 vs. 1 2.05; 95% confidence interval CI 1.23–3.41) and death from this disease (SHRTertile 3 vs. 1 1.97; 95% CI 1.13–3.41). Similar results were obtained for DII score from food only. A nonlinear dose–response pattern was identified for the aforementioned associations (all pnonlinearity < 0.05). Overall, a more pro‐inflammatory diet, as suggested by higher DII scores, is associated with higher risks of PLC incidence and mortality. These findings indicate that encouraging intake of more anti‐inflammatory dietary components and reducing intake of pro‐inflammatory components represent an attractive strategy to reduce PLC incidence and mortality.
What's new?
Chronic inflammation can be influenced by dietary habits. It also appears to play an important role in the etiology of primary liver cancer (PLC). Does a pro‐inflammatory diet therefore increase the risk of PLC? In this study, the authors used the “dietary inflammatory index” (DII) and found that the answer is yes, in terms of both PLC incidence and mortality. These results suggest that encouraging the consumption of more anti‐inflammatory dietary components and reducing consumption of pro‐inflammatory components represents an attractive strategy to reduce PLC risk and improve prognosis.
Liver transplantation has been deemed the best choice for end-stage liver disease patients but immune rejection after surgery is still a serious problem. Patients have to take immunosuppressive drugs ...for a long time after liver transplantation, and this often leads to many side effects. Mesenchymal stem cells (MSCs) gradually became of interest to researchers because of their powerful immunomodulatory effects. In the past, a large number of in vitro and in vivo studies have demonstrated the great potential of MSCs for participation in posttransplant immunomodulation. In addition, MSCs also have properties that may potentially benefit patients undergoing liver transplantation. This article aims to provide an overview of the current understanding of the immunomodulation achieved by the application of MSCs in liver transplantation, to discuss the problems that may be encountered when using MSCs in clinical practice, and to describe some of the underlying capabilities of MSCs in liver transplantation. Cell–cell contact, soluble molecules, and exosomes have been suggested to be critical approaches to MSCs’ immunoregulation in vitro; however, the exact mechanism, especially in vivo, is still unclear. In recent years, the clinical safety of MSCs has been proven by a series of clinical trials. The obstacles to the clinical application of MSCs are decreasing, but large sample clinical trials involving MSCs are still needed to further study their clinical effects.
The incorporation of a stiff and brittle phase into a soft and flexible polymer network makes double network hydrogels remarkably tougher than the conventional one. It also induces a stress softening ...in cyclic loading, which is seemingly identical to that of filled rubbers. Therefore, material models proposed for double network hydrogel are mostly based on continuum damage theories of filled elastomers. However, recent experimental studies clearly distinguish double network hydrogels from filled elastomers by the damage cross-effect in multiaxial deformation. In this paper, a micromechanical model for double network hydrogels under multiaxial deformation is proposed on the basis of the analytical network-averaging concept. Accordingly, the directional fracture of the first network results from cumulative damage in all directions. Furthermore, the strong interpenetration of the two networks is taken into account. The proposed analytical model includes very few physically motivated material constants and demonstrates excellent agreement with comprehensive experimental data of double network hydrogels under multiaxial loading conditions.
Background
To investigate the distribution of metastatic cancer cells in the mesentery (referred to as metastasis V) and enrich the understanding of the metastasis of colorectal cancer.
Methods
A ...total of two hundred ninety-nine patients who received colorectal operations at the Department of Gastrointestinal Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology between April 2018 and December 2018 were included. Samples were acquired from the dissected mesentery after the operation, and hematoxylin–eosin staining or immunohistochemistry was used to detect metastatic cancer cells. Pathological factors, including tumor position, tumor size, invasion depth, tumor differentiation, lymph node involvement, local vessel invasion, and perineural invasion, were recorded.
Results
Metastatic cancer cells in the colorectal mesentery (metastasis V) were detected in 62 of 299 patients. Metastasis V was closely correlated with tumor invasion depth, lymph node metastasis, tumor differentiation, and perineural and vessel invasion by cancer cells. Metastasis V occurred more frequently in patients with T3 stage (26.27%) and T4 stage (40.00%) than in patients with T1 and T2 stages (0% and 2%, respectively). Metastasis V was frequently detected in patients with N2a and N2b stage tumors (51.72% and 61.54%, respectively). Metastasis V was more frequently detected in patients with perineural metastasis and local vessel invasion. In addition, metastasis V incidences in colon and rectal cancer were similar.
Conclusion
The incidence rate of metastasis V is correlated with tumor staging factors and occurs more frequently in advanced-stage patients.
Highlights • The combination method resulted in a satisfactorily high yield of 5–6 × 106 KCs per liver. • The results of immunofluorescence and flow cytometry showed that the percentage of F4/80 ...positive cells accounted for 98.50% and 87.27%, respectively. • The isolated KCs possess high phagocytic activity. • The isolated cells had abilities to produce specific cytokines such as TNF-α in response to bacterial endotoxin.
The cyclic stretching measurements in various geometries including uniaxial, planar, unequal, and equal biaxial extension reveal the distinctive features of the internal fracture in the double ...network (DN) hydrogels with high toughness, which are composed of the rigid and brittle first network and the soft and ductile second network. The initial modulus, residual strain after unloading, dissipated energy (D), dissipation factor (Δ; the ratio of D to input strain energy), and the ultimate elongation of network strands (λi,m*) in each loading–unloading cycle are evaluated as a function of the imposed maximum elongation in the i-direction (λ i,m, i = x, y) in each cycle. The modulus reduction and Δ depend on the stretching mode when compared at the same λ i,m, but each of them exhibits a universal relation independently of the stretching mode when the corresponding magnitude of the deformation tensor (m m; m m = (I 1,m 2 – 2I 2,m)1/2 where I 1,m = λ x,m 2 + λ y,m 2 + λ z,m 2 and I 2,m = λ x,m 2λ y,m 2 + λ y,m 2λ z,m 2 + λ z,m 2λ x,m 2) is used as a variable. This is in contrast to that Δ of the filler-reinforced elastomers, which undergo apparently similar mechanical hysteresis, which shows the corresponding universal relation using I 1,m as a variable. The difference in governing variable indicates that the influence of the cross-effect of strains (λ i λ j ; i,j = x,y,z and i ≠ j) on Δ is pronounced in the DN gels whereas it is minimal in the filled elastomers. Characteristically, λ i,m* is close to λ i,m in every type of deformation, indicating that in the end of the loading most of the chains with lower extensibility than λ i,m undergo fracture whereas most of the long chains with higher extensibility than λ i,m remain intact. The elongation λ i,m* has no appreciable cross-effect of strains in contrast to the modulus reduction as well as Δ.
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