共查询到20条相似文献,搜索用时 203 毫秒
1.
Lee TS Park KK Cho HS Choo YA Hwang M 《Journal of materials science. Materials in medicine》2008,19(3):1425-1431
Vascular smooth muscle cells (VSMCs) play a pivotal role in vascular injury through proliferation and migration. Pro-inflammatory
cytokines and cyclooxygenase (COX)-2 and nitric oxide synthase (NOS) are highly associated with the pathogenesis of VSMCs.
We investigated the effect of bioactive ceramics on the expression of inflammatory cytokines, COX-2, and inducible NOS (iNOS)
induced by phorbol 12-myristate 13-acetate (PMA) in rat VSMCs. The ceramics inhibited mRNA expression of IL-1β, TNF-α, IL-6,
COX-2, and iNOS. Prostaglandin release was also diminished by the ceramics. The bioactive ceramics effect on cytokines, COX-2,
and iNOS expression was achieved by inhibition of NF-κB activity. Interestingly, the ceramics-induced up-regulation of expression
of endothelial NOS resulted in an increase of nitric oxide production. Thus, bioactive ceramics may have dual effects on the
pathogenesis of VSMCs by regulation of NF-κB activity and NO production. 相似文献
2.
Taira M Sasaki M Kimura S Araki Y 《Journal of materials science. Materials in medicine》2008,19(5):2173-2178
The effect of Ni (II) ions on macrophages is not well understood. The purpose of this study was to examine the dose-dependent
effects of Ni (II) ions up to 1,000 μmol/L on production of three inflammatory cytokines (TNF-α, IL-1β and IL-6), superoxide
dismutase (SOD) and nitric oxide (NO) by murine macrophage-like RAW264 cells with (+) or without (−) lipopolysaccharide (LPS)
-stimulation. Ni (II) ions caused LPS (−) RAW264 cells to slightly increase production of TNF-α and IL-6, proportionally to
the Ni (II) ion concentration while IL-1β was not produced, and to slightly increase production of SOD and NO. It can be concluded
that Ni (II) ions dose-dependently increased the inflammatory and oxidative stress conditions of LPS (−) RAW264 cells. LPS-stimulation
caused RAW264 cells to produce in abundance the three inflammatory cytokines, SOD and NO. Ni (II) ions dose-dependently reduced
the three cytokine quantities and NO amounts in LPS (+) RAW264 cells, while dose-independently increasing SOD amounts. It
was noted that Ni (II) ions dose-dependently reduce the resistance power against bacteria of LPS (+) macrophages, because
the production of volatile NO—bacteria killer is diminished proportionally to the Ni (II) ion concentration. 相似文献
3.
Zhi Cheng Li Lena Smuk Bill Bergman 《Journal of Materials Science: Materials in Electronics》2004,15(8):561-567
(Ba0.69Pb0.31)TiO3 ceramics were prepared using Al2O3, SiO2, additives and excess of TiO2 (AST). The characteristics of positive temperature coefficient of resistivity (PTCR) was studied and the corresponding microstructures were investigated using atomic force microscopy and scanning electron microscopy. The results showed that the PTCR effect was related to the AST additives. The maximum value of resistivity in the ceramics with lower content of or without Al2O3 and SiO2 additives was much lower than in those with AST additives. Ceramics with low AST content, which were heated by electric field to a temperature much higher than their Curie temperature, lost the PTCR effect after the electric field stimulation. The microstructure observations revealed that re-crystallization took place in the ceramics with lower content of or without AST additives resulting in the loss of the PTCR effect. 相似文献
4.
Masayuki Taira Tadayoshi Kagiya Hidemitsu Harada Minoru Sasaki Shigenobu Kimura Takayuki Narushima Takashi Nezu Yoshima Araki 《Journal of materials science. Materials in medicine》2010,21(1):267-275
This study was performed to microscopically observe and measure inflammatory cytokine production by human macrophages phagocytosing
submicron titanium (Ti) particles. Observations with secondary electron microscopy (SEM), SEM/electron probe microanalysis
(EPMA) and transmission electron microscopy (TEM) indicated that macrophages [phorbol-12-myristate-13-acetate (PMA)-differentiated
THP-1 cells] at 24 h in culture actively phagocytosed and accumulated submicron Ti particles in intracellular phagosomes,
in which refinement of Ti particles occurred. The macrophages were also cultured for 24 h in four media with and without submicron
Ti particles and lipopolysaccharide (LPS; components of bacteria). Whilst neither stimulus reduced cell viability, submicron
Ti particles and LPS activation independently and synergistically caused the macrophages to produce three inflammatory cytokines
(TNF-α, IL-1β and IL-6) at high levels in the culture supernatants. The inflammatory and osteolysis conditions caused by macrophages
phagocytosing submicron Ti particles would be worsened by challenge with LPS in patients wearing Ti prostheses. 相似文献
5.
Anand P. Khandwekar Deepak P. Patil Yogesh S. Shouche Mukesh Doble 《Journal of materials science. Materials in medicine》2010,21(2):635-646
Sulfobetaine-modified polymethylmethacrylate (PMMA) systems were created by physically entrapping the zwitterionic species
on the PMMA surface. The presence of the sulfobetaine molecules on these surfaces were verified by ATR–FTIR and SEM–EDAX analysis,
while wettability of the films was investigated by dynamic contact angle measurements. The short-term (4 h) adhesion of two
bacterial species (gram-positive Staphylococcus aureus and gram-negative Pseudomonas aeruginosa) on these surfaces were studied. Mouse RAW 264.7 macrophage cells were used to assess the cell adhesion and inflammatory
response by quantifying the expression levels of proinflammatory cytokines namely TNFα and IL1β by measuring their mRNA profiles
in the cells using real-time polymerase chain reaction (RT-PCR) normalized to the house keeping gene GAPDH. Whilst mouse L-929
fibroblast cells were used to assess the propensity for the materials to support fibroblast cell adhesion. A decrease in the
adhesion of S. aureus by 63% and P. aeruginosa by 49% was observed on sulfobetaine modified PMMA films after 4 h. In all the cases, sulfobetaine modified PMMA films reduced
cellular adhesion events (*P < 0.05) with respect to the base materials, which could be linked to the reduced protein adsorption observed on these surfaces.
The cellular inflammatory response was suppressed on sulfobetaine modified substrates as expression levels of pro-inflammatory
cytokines (TNFα and IL1β) was found to be up regulated on bare PMMA, while it was significantly lower on sulfobetaine modified
PMMA (**P < 0.001). Thus the sulfobetaine entrapment process can be applied on polymethylmethacrylate in order to achieve low biointeractions
and reduced inflammatory host responses for various biomedical and biotechnological applications. 相似文献
6.
Xue-Yuan Jin Chuan-Bao Zhu Shi-Yong Fan Jia-Lin Sun Yu-Cong Shi Chu-Han Wang 《Drug development and industrial pharmacy》2019,45(6):995-998
Novel fatty acid–bile acid conjugates (1a–1k) were designed and synthesized by coupling of the fatty acids to the 3-OH of bile acids using lysine for linkage. In the conjugates, the 24-COOH of the bile acids was kept intact to preserve liver-specific recognition. The ability of the newly synthesized conjugates (at 100?mg/kg dosage) to reduce total cholesterol (TC) and triglyceride (TG) levels in mice fed with high-fat diet (HFD) was evaluated. Conjugates of stearic acid with cholic acid and palmitic acid with ursodeoxycholic acid (at dosages of 50, 100, and 200?mg/kg) were further evaluated to determine their ability to reduce aspartate aminotransferase (AST), alanine aminotransferase (ALT), TC, and TG levels in mice fed with HFD. All conjugates showed potent hypolipidemic activity. Further investigation revealed that compounds 1c and 1?g not only dose-dependently reduced serum levels of TC and TG, but also inhibited the elevation of serum AST and ALT levels in mice fed with HFD. Thus, compounds 1c and 1?g are promising hypolipidemic agents with hepatocyte protective effects against HFD-induced liver damage. 相似文献
7.
Oxidation mechanisms in Si-Al-O-N ceramics 总被引:2,自引:0,他引:2
Oxidation mechanisms in single- and two-phase Si-Al-O-N ceramics have been studied using scanning and transmission electron
microscopy together with energy-dispersive X-ray microanalysis. Silicate layers formed on single-phase (β′) ceramics are non-crystalline, with viscosity and resulting oxidation kinetics controlled by outward diffusion of grainboundary
segregated impurities. Aluminium substitution inβ′ is important in compensating for the viscosity reduction imposed by the divalent ion impurities and inhibiting crystallization.
Crystallization, induced only on slow furnace cooling, produces mullite and cristobalite phases. Two-phase (β′and matrix) ceramics exhibit comparatively poor oxidation kinetics with formation of a porous crystalline silicate layer due
to the continued availability of a high concentration of metallic ions in the matrix phase. 相似文献
8.
The microstructures ofβ′-Si-Al-O-N ceramics of base composition Si4Al2O2N6 with large MgO additive (6 to 7 wt %) have been compared in the hot-pressed and sintered conditions. In both ceramics Mg
shows only a small solubility inβ′ crystals and is mainly segregated in a “matrix” phase. In hot-pressed materials this is an Mg-Al-silicate glass whereas in
sintered materials, inhomogeneities in composition and internal cavities are believed to catalyse its crystallization as the
spinel phase (MgAl2O4 with partial Si substitution). A minor phase in sintered ceramics is the 15R “polytype” of the AlN structure. 相似文献
9.
Observation and quantitative analysis of rat bone marrow stromal cells cultured in vitro on newly formed transparent β-tricalcium phosphate 总被引:3,自引:0,他引:3
Kotobuki N Kawagoe D Nomura D Katou Y Muraki K Fujimori H Goto S Ioku K Ohgushi H 《Journal of materials science. Materials in medicine》2006,17(1):33-41
To observe living cell morphology on ceramics by light microscopy, we fabricated a new material—transparent β - tricalcium
phosphate (t-β TCP) ceramic—for the purpose of serving as a tissue culture substrate. Bone marrow stromal cells (BMSCs) were obtained
from rat femora and cultured on both t-β TCP ceramic disks and culture grade polystyrene (PS) dishes in an osteogenic medium. After 1 day of culture, cell attachment
and spreading on both the t-β TCP and PS substrata were equally and clearly detected by ordinary light microscopy. After 14 days of culture, extensive
cell growth, alkaline phosphatase (ALP) staining, and bone mineral deposition could be detected on both substrata. In addition,
quantitative biochemical analyses revealed high DNA content, ALP activity, and osteocalcin content of these cultures. This
experiment is significant in that all of the results were similarly observed on both the t-β TCP and PS substrata, indicating the excellent properties of β TCP ceramics for BMSCs culture towards osteogenic differentiation. 相似文献
10.
de Carlos A Borrajo JP Serra J González P León B 《Journal of materials science. Materials in medicine》2006,17(6):523-529
The aim of this study was to test the in vitro cytotoxicity of wood-based biomorphic Silicon Carbide (SiC) ceramics coated with bioactive glass, using MG-63 human osteoblast-like
cells, with a view to their application in bone implantology. To better understand the scope of this study, it should be taken
into account that biomorphic SiC ceramics have only recently been developed and this innovative product has important properties
such as interconnected porosity, high strength and toughness, and easy shaping.
In the solvent extraction test, all the extracts had almost no effect on cellular activity even at 100% concentration, and
cells incubated in the bioactive glass-coated SiC ceramics extracts showed a proliferation rate similar to that of the Thermanox
control. There were no significant differences when the cellular attachment response of the cells on the wood-based biomorphic
SiC ceramics, uncoated or coated with bioactive glass, was compared to the one exhibited by reference materials like Ti6Al4V
and bulk bioactive glass. This fact looks very promising for biomedical applications. 相似文献
11.
Fangli Yu Jianfeng Yang Yaohui Xue Jun Du Yuan Lu Jiqiang Gao 《Bulletin of Materials Science》2009,32(2):177-181
Porous Si3N4 ceramics were successfully synthesized using cheaper talc and clay as sintering additives by pressureless sintering technology
and the microstructure and mechanical properties of the ceramics were also investigated. The results indicated that the ceramics
consisted of elongated β-Si3N4 and small Si2N2O grains. Fibrous β-Si3N4 grains developed in the porous microstructure, and the grain morphology and size were affected by different sintering conditions.
Adding 20% talc and clay sintered at 1700°C for 2 h, the porous Si3N4 ceramics were obtained with excellent properties. The final mechanical properties of the Si3N4 ceramics were as follows: porosity, P
0 = 45·39%; density, ρ = 1·663·g·cm−3; flexural strength, σ
b (average) = 131·59 MPa; Weibull modulus, m = 16·20. 相似文献
12.
13.
Klein B Schiffer R Hafemann B Klosterhalfen B Zwadlo-Klarwasser G 《Journal of materials science. Materials in medicine》2001,12(5):419-424
The inflammatory response to a collagen/elastin membrane was studied by measuring the expression of cytokines and function associated antigens in human macrophages. Additionally the angiogenic and inflammatory activity in the chorioallantoic membrane of the chick embryo (CAM-assay) was investigated. Macrophages cultured on the membrane expressed IL-1 mRNA as early as after 4 hours. During prolonged culturing IL-1 mRNA levels decreased. Messenger RNA for IL-8 was detectable over the whole culture period. The anti-inflammatory cytokine IL-10 was expressed up to one day only. Phenotypic analysis revealed a decrease in the number of chronic inflammatory 25F9 positive macrophages not migrating into the membrane but a presence of these cells together with the acute inflammatory 27E10 macrophages within the membrane whereas the anti-inflammatory subtype RM3/1 was absent. In the CAM-assay the membrane stimulated angiogenesis and induced the formation of granulation tissue. Histological analysis showed that the membrane was infiltrated with macrophages, fibroblasts and endothelial cells and locally with granulocytes. These data show that the collagen/elastin membrane causes activation of macrophages, angiogenesis and the formation of inflammatory tissue. Although these processes are essential for wound healing the type of inflammation points to a chronic process which might counteract an efficient scar formation. © 2001 Kluwer Academic Publishers 相似文献
14.
Ceramics of zirconium titanate, ZrTiO4, were prepared by the mixed oxide route, sintered at 1400 °C and cooled at various rates: water quench to 1 °C h–1. Mixed oxide-prepared ceramics of Zr5Ti7O24 were sintered at 1400 °C and cooled at 6 °C h–1. TEM analysis of the ZrTiO4 ceramics showed the development of an incommensurate superstructure in the more slowly cooled specimens. The Zr5Ti7O24 ceramics exhibited a commensurate superstructure with a tripleda-axis. Raman spectra were obtained from polished ceramic specimens at room temperature. Major differences between spectra for ZrTiO4 ceramics are believed to reflect differences in the degree of cation ordering. The Raman spectrum for Zr5Ti7O24 is similar to that of slowly cooled ZrTiO4 but there are significant differences. 相似文献
15.
The processing of alumina ceramics using the sol-gel technique was investigated. Alumina sols were prepared by precipitation-peptization
of aluminium hydroxide obtained from aluminium nitrate and aluminium oxyhydroxide obtained from aluminium isopropoxide. Sols
cast on Teflon substrate were gelled by controlled dehydration at near-ambient temperature. Gels were converted to ceramics
through processes of drying, calcination and sintering in the temperature range 773–1473 K. Ceramics derived from both the
sols retained a porosity of 35–45% even after sintering at 1273 K. However, at 1473 K densification was drastically enhanced
and bodies could be sintered to about 90–93% of theoretical density (TD) and was accompanied by theϑ-to-α transformation. The progress of the reactions occurring at various stages of the process was studied using pycnometry, TG-DSC,
XRD, SEM, MIP and TEM techniques. 相似文献
16.
In this paper we report the evolution of the polar cluster like behavior with the incorporation of Ti4+ ion in BaZrO3 Ceramics. Dielectric behavior of BaZrxTi(1−x)O3 (x = 1.00, 0.95, 0.90, 0.85) ceramics is studied in the temperature range from 300 to 30 K. Polar cluster like behavior becomes more prominent with the increase in content of Ti4+ ion. The dielectric relaxation is analyzed by Vogel–Fulcher relation and Arrhenius law. Frequency dependence of dielectric constant and low loss tangent of these materials can be useful for the potential applications at low temperature. 相似文献
17.
Luis Meseguer-Olmo Salvador Aznar-Cervantes Patricia Mazón Piedad N. De Aza 《Journal of materials science. Materials in medicine》2012,23(12):3003-3014
This work describes the evaluation of three ceramic materials as potential osteogenic substrate for bone tissue engineering. The capacity of adult human mesenchymal stem cells cultured under experimental conditions known to adhere, proliferate and differentiate into osteoblasts was studied. Two types of culture medium: growth medium and osteogenic medium were evaluated. The materials were pure ??-tricalcium phosphate and also ??TCP doped with either 1.5 or 3?wt% of dicalcium silicate. The results showed that the hMSCs cultured adhered, spread, proliferated and produced mineralized extracellular matrix on all the ceramics studied. They showed an osteoblastic phenotype, especially in the ??TCP doped with 1.5?wt% C2S, indicating osteoblastic differentiation as a result of the increased concentration of silicon in solid solution in TCP. Ceramics evaluated in this work are bioactive, cytocompatible and capable of promoting the differentiation of hMSCs into osteoblast. 相似文献
18.
《Current Opinion in Solid State & Materials Science》1999,4(5):461-465
Ceramics superplasticity has been one of the intensive research fields in the last decade. Although most of the reports are still limited to those of zirconia, new developments have been achieved in superplasticity of Si3N4 and SiC in recent years. It is clearly demonstrated that the superplasticity is one of the common properties of fine-grained ceramics at elevated temperatures. Superplastic forming and strengthening by superplastic forging are applicable to a wide range of ceramics including oxides, non-oxides, and ceramics with/without intergranular glass phase. 相似文献
19.
Ziying Zhang Jianfeng Jia Huizhi Yang Changqing Chen Hongwei Sun Xing Hu Delin Yang 《Journal of Materials Science》2008,43(5):1501-1504
Dense lead-free binary system piezoelectric ceramics (1 − x)[Bi0.5(Na0.7K0.25Li0.05)0.5]TiO3−xBa(Ti0.95Zr0.05)O3 (BNKLT–BZT) were prepared by a two-step sintering process. A phase transition from rhombohedral to tetragonal was observed
with increasing BZT fraction in the range x = 0.06–0.1 and the morphotropic phase boundary (MPB) between rhombohedral and tetragonal appears in this range. Ceramics
containing 10 mol% BZT with tetragonal phase near the MPB region has the maximum piezoelectric constant d
33(151pC/N). 相似文献
20.
Al2O3含量对Al2O3/LiTaO3复合陶瓷介电性能的影响 总被引:1,自引:0,他引:1
采用热压烧结法制备了Al2O3/LiTaO3 (ALT) 陶瓷复合材料, 研究了Al2O3不同体积含量(5vol%、10vol%、15vol%和20vol%)对LiTaO3压电陶瓷介电性能的影响. 结果表明:随着频率的增加, 不同Al2O3含量的ALT陶瓷复合材料的介电常数和介电损耗均降低, 但降低的幅度不同. 少量Al2O3(5vol%)的添加既能增大材料的介电常数同时又降低了材料的介电损耗, 但是随着Al2O3含量的继续增加, ALT陶瓷复合材料的介电常数和介电损耗都增大, 其居里温度先升高后降低. Al2O3作为第二相不但能促进LiTaO3陶瓷烧结致密,而且对ALT陶瓷复合材料的介电性能也有提高. 相似文献