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Expansion System (expansion + system)
Selected AbstractsThe effect of temperature on viscosity of root canal sealersINTERNATIONAL ENDODONTIC JOURNAL, Issue 11 2006S. Lacey Abstract Aim, To test the hypothesis that there was no significant (, = 0.05) change in viscosity of commercially available root canal sealers with increase in temperature using a high-performance Advanced Rheometric Expansion System (ARES) rheometer. Methodology, Materials tested were Apexit, Tubliseal EWT, Grossman's, AH Plus and Ketac-endo. Cone-and-plate geometry was used (25-mm diameter, 0.1 radian and gap 0.051 mm). Measurements were carried out for steady-state viscosity at 25 and 37 °C in the shear rate range of 0.001,50 s,1 at standardized relative humidity and within 30 min from the start of mixing. Five samples were taken for each sealer at each temperature. Results, At 25 °C all sealers demonstrated shear thinning. At 37 °C Grossman's (powder : liquid ratio 2 : 1 and 3 : 1) and Ketac-endo had a rapid rise in viscosity and early set whereas the other sealers were shear thinning. On increasing temperature from 25 °C to 37 °C, Apexit, Tubliseal and AH Plus had reduced viscosity whereas Grossman's 2 : 1, Grossman's 3 : 1 and Ketac-endo had increased viscosity, which varied with the shear rate. The change in viscosity with change in temperature was significant (P < 0.05) for all sealers except AH Plus. Conclusions, There was a variation in the effect of increasing temperature on each sealer depending on the shear rate. With the exception of AH Plus, a significant (P < 0.05) change in viscosity was found, and the null hypothesis was rejected. [source] Thermogelling behaviors of poly(caprolactone- b -ethylene glycol- b -caprolactone) triblock copolymer in the presence of hyaluronic acidJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2008In Yong Kim Abstract In this article, we studied the effect of hyaluronic acid (HA) on thermogelation of poly(caprolactone- b -ethylene glycol- b -caprolactone) (PCL-PEG-PCL) aqueous solution designed as an injectable system for prevention of postsurgical tissue adhesion. The PCL-PEG-PCL triblock copolymers were simply synthesized by ring-opening polymerization of ,-caprolactone (CL) in the presence of PEG as a polymeric initiator. The synthesized copolymers were confirmed by proton nuclear magnetic resonance (1H-NMR) spectroscopy. Possible interactions between HA and PCL-PEG-PCL triblock copolymers in the blend were evaluated by Fourier-transform infrared spectroscopy (FTIR). The effect of HA on the micellization of PCL-PEG-PCL aqueous solution was investigated by dye solubilization method and electrophoretic lighting scattering (ELS) spectrophotometer. Also, the thermogelling behaviors of the PCL-PEG-PCL triblock copolymers in the presence of HA and their mechanism were investigated by test tube inverting method, 13C-NMR, 1H-NMR, Advanced Rheometic Expansion System (ARES), and differential scanning calorimetry (DSC). The PCL-PEG-PCL/HA blend aqueous solutions undergo the sol-gel-sol transition in response to an increase in temperature (10,60 °C) and the gelation of the PCL-PEG-PCL was rather accelerated by HA. Presumably, this accelerated gelation seems to arise from the attractive interactions between them and the effect of chain confinement in the micelle corona region. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3629,3637, 2008 [source] The shared tumor associated antigen cyclin-A2 is recognized by high-avidity T-cellsINTERNATIONAL JOURNAL OF CANCER, Issue 10 2009Eisei Kondo Abstract Cyclin-A2, a key cell cycle regulator, has been shown to be overexpressed in various types of malignancies with little expression in normal tissue. Such tumor-associated genes potentially are useful targets for cancer immunotherapy. However, high-avidity cyclin-specific T cells are considered to be thymically deleted. We identified at least one nonameric HLA-A*0201 binding cyclin-A2 epitope by a reverse immunology approach. Using a highly efficient T-cell expansion system that is based on CD40-activated B (CD40-B) cells as sole antigen-presenting cells we successfully generated cyclin-A2 specific CTL from HLA-A*0201+ donors. Interestingly, high-avidity cyclin-A2 specific CTL lines, which recognized peptide-pulsed and antigen expressing target cells, were indeed generated by stimulation with CD40-B cells when pulsed with low concentrations of peptide, whereas CD40-B cells pulsed at saturating concentrations could only induce low-avidity CTL, which recognized peptide-pulsed target cells only. One high-avidity CTL line was subcloned and CTL clones, whose peptide concentration required for half-maximal lysis were less than 1 nM, could lyse cyclin-A2 expressing tumor cells. Taken together, cyclin A2 is an attractive candidate for immune intervention in a significant number of cancer patients and high-avidity T cells can be readily generated using CD40-B cells as antigen-presenting cells. © 2009 UICC [source] Maintenance of pluripotency in mouse embryonic stem cells cultivated in stirred microcarrier culturesBIOTECHNOLOGY PROGRESS, Issue 2 2010Paulo A. N. Marinho Abstract The development of efficient and reproducible culture systems for embryonic stem (ES) cells is an essential pre-requisite for regenerative medicine. Culture scale-up ensuring maintenance of cell pluripotency is a central issue, because large amounts of pluripotent cells must be generated to warrant that differentiated cells deriving thereof are transplanted in great amounts and survive the procedure. This study aimed to develop a robust scalable cell expansion system, using a murine embryonic stem cell line that is feeder-dependent and adapted to serum-free medium, thus representing a more realistic model for human ES cells. We showed that high concentrations of murine ES cells can be obtained in stirred microcarrier-based spinner cultures, with a 10-fold concentration of cells per volume of medium and a 5-fold greater cell concentration per surface area, as compared to static cultures. No differences in terms of pluripotency and differentiation capability were observed between cells grown in traditional static systems and cells that were replated onto the traditional system after being expanded on microcarriers in the stirred system. This was verified by morphological analyses, quantification of cells expressing important pluripotency markers (Oct-4, SSEA-1, and SOX2), karyotype profile, and the ability to form embryoid bodies with similar sizes, and maintaining their intrinsic ability to differentiate into all three germ layers. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Lidocaine/Monoethylglycinexylidide Test, Galactose Elimination Test, and Sorbitol Elimination Test for Metabolic Assessment of Liver Cell BioreactorsARTIFICIAL ORGANS, Issue 6 2010Jörg C. Gerlach Abstract Various metabolic tests were compared for the performance characterization of a liver cell bioreactor as a routine function assessment of cultures in a standby for patient application in clinical studies. Everyday quality assessment (QA) is essential to ensure a continuous level of cellular functional capacity in the development of hepatic progenitor cell expansion systems providing cells for regenerative medicine research; it is also of interest to meet safety requirements in bioartificial extracorporeal liver support systems under clinical evaluation. Quality criteria for the description of bioreactor cultures were developed using primary porcine liver cells as a model. Porcine liver cells isolated by collagenase perfusion with an average of 3 × 109 primary cells were used in 39 bioreactors for culture periods up to 33 days. Measurements of monoethylglycinexylidide synthesis and elimination of lidocaine, galactose elimination, and sorbitol elimination proved to be useful for routine QA of primary liver cell cultures. We demonstrate two methods for dispensing test substances, bolus administration and continuous, steady-state administration. Bolus test data were grouped in Standard, Therapy, Infection/Contamination, and Cell-free control groups. Statistical analyses show significant differences among all groups for every test substance. Post hoc comparisons indicated significant differences between Standard and Cell-free groups for all elimination parameters. For continuous tests, results were categorized according to number of culture days and time-dependent changes were analyzed. Continuous administration enables a better view of culture health and the time dependency of cellular function, whereas bolus administration is more flexible. Both procedures can be used to define cell function. Assessment of cellular function and bioreactor quality can contribute significantly to the quality of experimental or clinical studies in the field of hepatic bioreactor development. [source] | ||||||||||