|
| ||
|
|
||
Cell Culture Studies (cell + culture_studies)
Selected AbstractsCytotoxic evaluation of injectable cyclodextrin nanoparticlesJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 5 2006Erem Memisoglu-Bilensoy Nanoparticles were prepared using ,-CDC6, which is an amphiphilic , -cyclodextrin derivative modified on the secondary face with 6C aliphatic esters. A nanoprecipitation technique was used to prepare the blank nanoparticles without any surfactant and nanoparticles containing Pluronic F68 as surfactant in a concentration range of 0.1 to 1%. Nanoparticle formulations were characterized by particle size distribution and zeta potential measurements. Entrapment efficiency and in-vitro release profiles were determined and the cytotoxicity of these injectable nanospheres was evaluated against mouse fibroblast L929 cell line and human polymorphonuclear cells by methlythiazolyltetrazolium assay. As far as particle size and zeta potential are concerned, there is a relationship between surfactant presence and nanoparticle characteristics. However, these effects are not significant. It was also found that surfactant presence has no effect on model drug nimodipine encapsulation but accelerates the in-vitro release of the drug. Cell culture studies on mouse fibroblasts and human polymorphonuclear cells revealed a concentration-dependent cytotoxicity more pronounced in fibroblast cells. This led to the conclusion that the use of surfactants in injectable nanoparticles prepared from amphiphilic ,-cyclodextrins may lead to altered in-vitro properties and impaired safety for the drug delivery system. [source] Temperature-Induced Hydrogels Through Self-Assembly of Cholesterol-Substituted Star PEG- b -PLLA Copolymers: An Injectable Scaffold for Tissue Engineering,ADVANCED FUNCTIONAL MATERIALS, Issue 8 2008Koji Nagahama Abstract Partially cholesterol-substituted 8-arm poly(ethylene glycol)- block -poly(L -lactide) (8-arm PEG- b -PLLA-cholesterol) has been prepared as a novel star-shaped, biodegradable copolymer derivative. The amphiphilic 8-arm PEG- b -PLLA-cholesterol aqueous solution (polymer concentration, above 3,wt%) exhibits instantaneous temperature-induced gelation at 34,°C, but the virgin 8-arm PEG- b -PLLA does not, irrespective of concentration. Moreover, an extracellular matrix (ECM)-like micrometer-scale network structure has been created with favorable porosity for three-dimensional proliferation of cells inside the hydrogel. This network structure is mainly attributed to specific self-assembly between cholesterol groups. The 10 and 20,wt% hydrogels are eroded gradually in phosphate buffered saline at 37,°C over the course of a month, and after that the gel becomes completely dissociated. Moreover, L929 cells encapsulated into the hydrogel are viable and proliferate three-dimensionally inside the hydrogels. Thus, in-vitro cell culture studies demonstrate that 8-arm PEG- b -PLLA-cholesterol is a promising candidate as a novel injectable cellular scaffold. [source] Photochemoprevention of skin cancer by botanical agentsPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 2 2003Sleem F'guyer Photochemoprevention has become an important armamentarium in the fight against ultraviolet radiation (UVR)-induced damage to the skin. Among many UVR-induced damages, skin cancer is of the greatest concern as its rates have been steadily increasing in recent years and the same trend is expected to continue in the future. Ultraviolet radiation increases oxidative stress in skin cells by causing excessive generation of reactive oxygen species (ROS), leading to cancer initiation and promotion. Antioxidants have the capability to quench these ROS and much recent work shows that some of these can inhibit many UVR-induced signal transduction pathways. Thus, identifying nontoxic strong antioxidants , capable of preventing UVR-induced skin cancer , has become an important area of research. The use of botanical antioxidants in skin care products is growing in popularity. A wide range of such agents has been shown to prevent skin cancer in animal model systems. New agents are constantly being investigated; however, only a few have been tested for their efficacy in humans. Animal model and cell culture studies have clarified that antioxidants act by several mechanisms at various stages of skin carcinogenesis. This review focuses on skin cancer photochemopreventive effects of selected botanical antioxidants. [source] Homocysteine is positively associated with cytokine IL-18 plasma levels in coronary artery bypass surgery patientsBIOFACTORS, Issue 2 2005Craig Steven Mclachlan Abstract Homocysteine, cytokines (IL-18, IL-6, IL-8) are involved in vascular inflammation and coronary artery disease. Homocysteine influences endothelial IL-6 and IL-8 cytokine expression and release, however, an association between homocysteine and IL-18 has not been previously investigated in endothelial/smooth muscle cells and or in coronary artery disease. We report in 9 coronary artery bypass surgery (CABG) patients a positive correlation r=0.86 between homocysteine and IL-18 plasma levels (p<0.05). Plasma IL-18 levels are significantly higher in those patients with elevated homocysteine compared to those with normal levels (p<0.02; 153 ± 19 pg/ml versus 116 ± 14 pg/ml respectively). Our in vitro cell culture studies suggest that the source of IL-18 in CABG patients with elevated homocysteine is not from vascular smooth muscle or endothelial cells. [source] Cellular senescence: Its role in tumor suppression and agingCANCER SCIENCE, Issue 5 2009Naoko Ohtani In normal tissue, cell division is carefully regulated to maintain the correct proliferative balance. Abnormal cell division underlies many hypoproliferative and hyperproliferative disorders, including cancer, and a better understanding of the mechanisms involved could lead to new strategies for treatment and prevention. Cellular senescence, a state of irreversible growth arrest, was first described as a limit to the replicative life span of somatic cells after serial cultivation in vitro. Recently, however, it has also been shown to be triggered prematurely by potentially oncogenic stimuli such as oncogene expression, oxidative stress, and DNA damage in cell culture studies. These data suggest that cellular senescence is therefore acting as a tumor-protective fail-safe mechanism. However, the significance of cellular senescence has remained an issue of debate over the years, with the possibility that it might be a cell culture-related artifact. Recent reports on oncogene-induced senescence detected in premalignant tumors have provided evidence to validate its role as a physiological response to prevent oncogenesis in vivo. In this review, we discuss the mechanisms for cellular senescence and its roles in vivo. (Cancer Sci 2009; 100: 792,797) [source] | ||||||||||