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The different steps of development of chemically induced brain tumors were investigated in rats by MRI using a superparamagnetic contrast agent, magnetite-dextran nanoparticles (MD3). Sprague-Dawley strain pregnant female rats were injected intravenously with ethynitrosourea solution at the end of pregnancy. Offspring whelped by the inoculated mother were followed. MRI examinations were performed at 0.5 T. MD3 nanoparticles were injected intravenously at a dose of 5 mg Fe kg-1 body weight 30 min before rat sacrifice. After sacrifice, histological slices were stained with hematoxylin-eosin. Relaxation times were measured at 40 MHz and 37°. MD3 nanoparticles act differently according to the step of the tumor development. Before tumor appearance, at a step characterized by the presence of abnormal cell clusters, relaxation time T2 increased significantly. The T2-weighted image showed a small increase in signal intensity in the lesion. Image contrast was improved by MD3 nanoparticles injection because of the decrease in healthy tissue signal intensity. The Tl-weighted image did not provide any additional information. In presence of a minute tumor, relaxation times decreased in tumor but increased in surrounding tissue. The Tl-weighted image showed a hypersignal on the border of an hyposignal. T2-weighted image showed a hypersignal in the same area. Signal intensity was not modified after MD3 nanoparticles injection. When new vascular capillaries developed in the tumor, MD3 nanoparticles cross into the cerebral parenchyma. Transmission electron microscopy showed magnetite crystals in this specific area on cytoplasm vesicles of glial cells and in tumor-specific membrane arrangements. On T2-weighted image, the hypersignal consisted of a well defined part and a second more fuzzy part, its signal being extinguished after MD3 nanoparticles injection. Necrotic areas and edema can be discriminated. The use of such a superparamagnetic contrast agent would be helpful in early detection of tumor development and in improving distinction of tumor mass from its vascular environment in patients. © 1998 Elsevier Science B.V. All rights reserved. 相似文献
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Dali ZHOU Weizhong YANG Guangfu YIN Changqiong ZHENG Yun Zhang Huaiqing CHEN Rui CHEN 《材料科学技术学报》2004,20(3)
To develop a novel degradable poly (L-lactic acid)/β-tricalcium phosphate (PLLA/β-TCP) bioactive materials for bone tissue engineering, β-TCP powder was produced by a new wet process. Porous scaffolds were prepared by three steps, I.e. Solvent casting, compression molding and leaching stage. Factors influencing the compressive strength and the degradation behavior of the porous scaffold, e.g. Weight fraction of pore forming agent-sodium chloride (NaCl), weight ratio of PLLA: β-TCP, the particle size ofβ-TCP and the porosity, were discussed in details. Rat marrow stromal cells (RMSC) were incorporated into the composite by tissue engineering approach. Biological and osteogenesis potential of the composite scaffold were determined with MTT assay, alkaline phosphatase (ALP) activity and bone osteocalcin (OCN) content evaluation. Results show that PLLA/β-TCP bioactive porous scaffold has good mechanical and pore structure with adjustable compressive strength needed for surgery. RMSCs seeding on porous PLLA/β-TCP composite behaves good seeding efficacy, biocompatibility and osteoinductive potential. Osteoprogenitor cells could well penetrate into the material matrix and begin cell proliferation and osteogenic differentiation. Osseous matrix could be formed on the surface of the composite after culturing in vitro. It is expected that the PLLA/β-TCP porous composites are promising scaffolds for bone tissue engineering in prosthesis surgery. 相似文献
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大鼠放射性皮肤溃疡组织中c-Fos、Rb蛋白表达研究 总被引:2,自引:0,他引:2
为研究大鼠放射性溃疡组织中c-Fos、Rb表达。采用140只Wistar大鼠进行局部照射(γ射线)制备放射性皮肤溃疡动物模型,观察病变1年,然后采用c-Fos、Rb多克隆抗体及免疫组化方法检测溃疡组织中c-Fos、Rb的表达情况。结果表明:c-Fos、Rb的表达阳性率分别为45.8%(33/72)、63.9%(46/72),两者阳性部位主要见于增生肥大的鳞状上皮细胞胞核、增生的间质成纤维细胞胞质及 相似文献
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We evaluated the effects of seven mushroom extracts (Grifola frondosa, Pholiota nameko, Panellus serotinus, Hypsizygus marmoreus, Pleurotus cornucopiae, Armillaria mellea, and Flammulina velutipes) on cytotoxic activity and cytokine production of lamina propria leukocytes (LPLs) isolated from rat small (S) and large (L) intestinal mucosa. Boiling water extracts from seven species of mushrooms showed no direct cytotoxicity against the YAC-1 target cells. However, prominent increases of cytotoxicity were observed in S- and L-LPLs co-cultured with P. serotinus extract. Cytokine production (TNFα, IFNγ, IL-12 p70, and IL-4) of S- and L-LPLs was stimulated in response to P. cornucopiae extract. Mushroom extracts contributed to target cell adhesion and/or cytokine production in the effector cells. The promotion of cytotoxic activity in S- and L-LPLs was not necessarily related to β-glucan content of the mushroom. 相似文献
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白桑椹对老年大鼠的抗老化与降脂作用研究 总被引:2,自引:1,他引:2
研究了白桑椹对老年大鼠的抗老化与降脂作用。将老年大鼠分成3组:对照组、10%白桑椹果汁组和10%白桑椹果组。各组饲养8周后,将大鼠的血清和血液用于各项指标的测定。同时,设置正常(非老年)组作比较。结果表明,与正常组比较,老年大鼠的红细胞各项抗氧化酶活性降低,脂质过氧化水平提高,抗动脉硬化指数降低。与老年对照组相比,白桑椹果汁和白桑椹果组大鼠的红细胞抗氧化酶SOD、GSH-Px、膜结合酶(Na+-K+-ATP)酶活性以及高密度脂蛋白胆固醇均被提高;膜脂流动性得到改善;桑椹组的血清和红细胞膜中脂质过氧化产物MDA含量和血液总胆固醇含量降低;抗动脉硬化指数与对照组相比显著升高(P<0.05)。表明白桑椹果与其果汁具有一定的抗老化、降脂和抗动脉硬化的效果。 相似文献
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Darina Slameňová Eva Horváthová Zuzana Kováčiková Katarína Kozics Ľubica Hunáková 《Food chemistry》2011
Rosemary oil (RO) is popular in the Mediterranean region as a culinary additive which has the ability to protect delicate organs such as liver, brain and heart. We examined the effect of RO consumption on resistance of rat testicular cells (TCs) against DNA-damaging effects of the oxidative agents H2O2 and DMNQ and on the activity of the antioxidant enzymes glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD). DNA lesions were detected by conventional and modified comet assay and the activities of GSH-Px and SOD were measured spectrophotometrically. Since TCs represent a mixture of haploid, diploid and tetraploid cells, we used flow cytometry for their differentiation and calculation of DNA-damaging effects of H2O2 and DMNQ in cells of different ploidy. The results showed that the oxidative DNA lesions were significantly reduced in TCs from rats administered RO; however, the activity of antioxidant enzymes did not differ in TCs from control and RO-supplemented rats. 相似文献