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Injection Model (injection + model)
Selected AbstractsHole Injection in a Model Fluorene,Triarylamine CopolymerADVANCED FUNCTIONAL MATERIALS, Issue 2 2009Hon Hang Fong Abstract Recent developments in synthesis and purification have yielded conjugated polymers with hole mobilities exceeding 0.01,cm2 V,1 s,1. Essential to harvesting the potential of these materials in organic light emitting diodes (OLEDs) is the identification of suitable ohmic contacts. Using a model fluorene copolymer that shows high-mobility, non-dispersive hole transport, it is demonstrated that electrodes commonly used as anodes in OLEDs are very poor hole injectors. Injection from Au and indium tin oxide anodes is limited by energy barriers of 0.75 and 0.65,eV, respectively, and the injected current is found to be temperature independent,a prediction that was not reproduced by the leading injection model for disordered organic semiconductors. Injection from a poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) anode, on the other hand, is found to become less efficient with electric field, a behavior which is currently not understood. In thinner poly[(9,9,-dioctylfluorenyl-2,7-diyl)- co -(4,4,-(N -(4- sec -butyl))diphenylamine)] films, which are of relevance to OLEDs, ohmic losses on the PEDOT:PSS layer are found to limit the flow of current. These results illustrate the opportunity to further improve the performance of OLEDs as well as the challenge posed by high mobility conjugated polymers for the design of hole injection layers. [source] Real-scale miscible grout injection experiment and performance of advection,dispersion,filtration modelINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 12 2001F. Bouchelaghem Abstract A model was developed, to describe miscible grout propagation in a saturated deformable porous medium, based on Bear's statistical model with spatial volume averaging. In a previous paper, the model was first successfully confronted to one-dimensional laboratory experiments. In the present paper, the numerical model is used to simulate practical grouting operation in a cylindrical injection model. The cylindrical injection model lends itself to study main flow and propagation character istics for a dispersed suspension-type grout, under axisymmetric conditions close to real scale conditions. Comparison between numerical solutions and experimental results is essential to confirm the validity and accuracy of the proposed model from a phenomenological standpoint. The numerical model performances show that the underlying mathematical model constitutes a realistic predictive model reproducing most prominent features during injection of a suspension-type grout into a deformable porous medium. The basic mechanism by which injected miscible grout permeates a soil mass is discussed in detail. Such a tool leads to quality control criteria for grouting on a theoretical basis, which complements existing criteria acquired through engineering practice. Copyright © 2001 John Wiley & Sons, Ltd. [source] Early Detection of Bone Metastases in a Murine Model Using Fluorescent Human Breast Cancer Cells: Application to the Use of the Bisphosphonate Zoledronic Acid in the Treatment of Osteolytic LesionsJOURNAL OF BONE AND MINERAL RESEARCH, Issue 11 2001Olivier Peyruchaud Abstract A very common metastatic site for human breast cancer is bone. The traditional bone metastasis model requires human MDA-MB-231 breast carcinoma cell inoculation into the left heart ventricle of nude mice. MDA-MB-231 cells usually develop osteolytic lesions 3,4 weeks after intracardiac inoculation in these animals. Here, we report a new approach to study the formation of bone metastasis in animals using breast carcinoma cells expressing the bioluminescent jellyfish protein (green fluorescent protein [GFP]). We first established a subclone of MDA-MB-231 cells by repeated in vivo passages in bone using the heart injection model. On stable transfection of this subclone with an expression vector for GFP and subsequent inoculation of GFP-expressing tumor cells (B02/GFP.2) in the mouse tail vein, B02/GFP.2 cells displayed a unique predilection for dissemination to bone. Externally fluorescence imaging of live animals allowed the detection of fluorescent bone metastases approximately 1 week before the occurrence of radiologically distinctive osteolytic lesions. The number, size, and intensity of fluorescent bone metastases increased progressively with time and was indicative of breast cancer cell progression within bone. Histological examination of fluorescent long bones from B02/GFP.2-bearing mice revealed the occurrence of profound bone destruction. Treatment of B02/GFP.2-bearing mice with the bisphosphonate zoledronic acid markedly inhibited the progression of established osteolytic lesions and the expansion of breast cancer cells within bone. Overall, this new bone metastasis model of breast cancer combining both fluorescence imaging and radiography should provide an invaluable tool to study the effectiveness of pharmaceutical agents that could suppress cancer colonization in bone. [source] The effects of RANK blockade and osteoclast depletion in a model of pure osteoblastic prostate cancer metastasis in boneJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2005Peter G. Whang Abstract Adenocarcinoma of the prostate exhibits a clear propensity for bone and is associated with the formation of osteoblastic metastases. It has previously been suggested that osteoclast activity may be necessary for the development of these osteoblastic metastases based on data from lytic and mixed lytic-blastic tumors. Here we investigate the effects of complete in vivo osteoclast depletion via the blockade of receptor activator of NF:,B (RANK) on the establishment and progression of purely osteoblastic (LAPC-9 cells) bone lesions induced by human prostate cancer cells using a SCID mouse intratibial injection model. The subcutaneous administration of the RANK antagonist (15 mg/kg) RANK:Fc did not prevent the formation of purely osteoblastic lesions, indicating that osteoclasts may not be essential to the initial development of osteoblastic metastases. However, RANK:Fc protein appeared to inhibit the progression of established osteoblastic lesions, suggesting that osteoclasts may be involved in the subsequent growth of these tumors once they are already present. In contrast, RANK:Fc treatment effectively blocked the establishment and progression of purely osteolytic lesions formed by PC-3 cells, which served as a positive control. These results indicate that in vivo RANK blockade may not be effective for the prevention of osteoblastic metastasis but may potentially represent a novel therapy that limits the growth of established metastatic CaP lesions in bone. © 2005 Published by Elsevier Ltd. on behalf of Orthopaedic Research Society. [source] Tumorigenic study on hepatocytes coexpressing SV40 with RasMOLECULAR CARCINOGENESIS, Issue 4 2006Beicheng Sun Abstract A model of neoplastic transformation by the combination of SV40 large T antigen (LT), SV40 small T antigen (ST), oncogenic Ras, and human telomerase reverse trasncriptase subunit (hTERT) has become established and replicated in primary human fibroblasts, however, there is no report on human hepatocytes. Here we use cell transplantation model, and show that transplantation of human hepatocytes of HL-7702 and HL-7703 expressing Ha-RasV12 and SV40 LT into subrenal capsule of immunodeficient mice results in fully malignant tumors, in contrast to conventional subcutaneous injections where tumors fail to develop. In GM-847 cell study, we have found that hTERT is not required for tumorigenic growth in subrenal capsule transplantation, however, it is required in subcutaneous injection assay. These results demonstrate that Human hepatocytes can be transformed under kidney capsule by coexpressing SV40 LT and Ha-RasV12, neither hTERT nor protein phosphatase 2A (PP2A) inhibition are required for malignant transformation, a gene which increases cell survival in the subcutaneous injection model is not required for tumorigenic growth in subrenal capsule. © 2005 Wiley-Liss, Inc. [source] Slow-release nanoparticle-encapsulated delivery system for laryngeal injection,THE LARYNGOSCOPE, Issue 5 2010Vasantha L. Kolachala PhD Abstract Objectives/Hypothesis: There is a need for a slow-release system for local delivery of therapeutics to the larynx. Most therapeutic substances, such as steroids or chemotherapeutic agents that are injected into the larynx are cleared rapidly. Repeated laryngeal injection of these substances at short intervals is impractical. Injectable encapsulated poly(lactide-co-glycolide) (PLGA) nanoparticles offer a potential slow-release delivery system for biologically active substances in the larynx. Study Design: Controlled animal study. Methods: PLGA nanoparticles were fabricated using a double emulsion method and were loaded with Texas Red-dextran (NPTR), hepatocyte growth factor (NPHGF), and bovine serum albumin (NPBSA). In vitro release of NPTR, NPBSA, and NPHGF was determined over approximately 2 weeks to assess potential duration of PLGA nanoparticle delivery. In vivo release of NPTR was assessed in a murine vocal fold injection model. The transcriptional effect of NPHGF on procollagen was measured in vitro to assess whether released growth factor retained functionality. Results: In vitro release kinetics demonstrated slow release of NPTR, NPBSA, and NPHGF over 12 to 14 days. In vitro NPTR release correlated with in vivo results. In vivo presence of NPTR occurred up to 7 days compared to 1 day for Texas Red control. In addition, NPHGF ameliorated transforming growth factor-, induced procollagen in vitro in 3T3 fibroblast cells. Conclusions: The results demonstrate the potential utility of nanoparticle encapsulation as an effective method for long-term delivery of specific drugs and biologically active substances to the larynx. Laryngoscope, 2010 [source] Bone Affinity of a Bisphosphonate-Conjugated Protein in VivoBIOTECHNOLOGY PROGRESS, Issue 6 2000Hasan Uludag Growth factors capable of stimulating bone formation are potential therapeutic agents for osteoporosis treatment. It is essential, however, that a targeting mechanism is incorporated into the growth factors to deposit them at osseous tissue with minimal distribution to extraskeletal sites. To this end, a strategy has been developed in which a bone-seeking molecule, 1-amino-1,1-diphosphonate methane (aminoBP), was chemically conjugated to a model protein, bovine serum albumin (BSA). This study was carried out to assess the bone affinity of the conjugates in a tibia injection model. Using ovariectomized (OVX) rats, initial (3 h) retention of BSA and aminoBP-BSA were found to be equivalent when injected into the medullary cavity of tibia. After 1 day, an 8- and 12-fold higher tibiae retention of the protein was obtained in normal and OVX rats as a result of aminoBP conjugation. A similar result (,12-fold difference) was also obtained in OVX rats after 3 days. We concluded that aminoBP conjugation to BSA imparted a high bone affinity and enhanced bone retention of proteins in normal and OVX rats. [source] | |||||||||||||