Osmotic delivery of flurbiprofen through controlled porosity asymmetric membrane capsule.
ABSTRACT The release of poorly water-soluble drug, flurbiprofen, through asymmetric membrane capsule of cellulose acetate containing different pore forming agents like glycerol, polyethylene glycol 400, and dibutyl phthalate, in presence of sodium lauryl sulfate was investigated. The asymmetric membrane was fabricated in the shape of capsule body and cap by phase inversion technique. The type of pore forming agent incorporated had a marked influence on the porosity of the asymmetric membrane. However flurbiprofen due to its poor solubility was unable to create enough osmotic pressure and hence less than 10% of drug was released from all the systems with out SLS. However when the study was conducted with SLS, a maximum release of 72% was observed from the capsule with 70% glycerol. The release rates were found to increase with the increase in the concentration of pore forming agent and the amount of SLS encapsulated.
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ABSTRACT: Although both embryonic stem cells (ESCs) and mesenchymal stem cells (MSCs) are known to have immunosuppressive effects, the mechanisms of immunosuppression are still controversial. Both types of stem cells suppressed not only the proliferation but also survival of CD4(+) T cells in vitro. They suppressed secretion of various cytokines (IL-2, IL-12, IFN-γ, TNF-α, IL-4, IL-5, IL-1β, and IL-10), whereas there was no change in the levels of TGF-β or IDO. Classic and modified transwell experiments demonstrated that immunosuppressive activities were mainly mediated by cell-to-cell contact. Granzyme B in the ESCs played a significant role in their immunosuppression, whereas PDL-1, Fas ligand, CD30 or perforin was not involved in the contact-dependent immunosuppression. However, none of the above molecules played a significant role in the immunosuppression by the MSCs. Interestingly, both stem cells increased the proportion of Foxp3(+) regulatory T cells. Our results showed that both ESCs and MSCs suppressed the survival as well as the proliferation of T cells by mainly contact-dependent mechanisms and increased the proportion of regulatory T cells. Granzyme B was involved in immunosuppression by the ESCs in a perforin-independent manner.Transplant Immunology 05/2011; 25(1):7-15. · 1.83 Impact Factor
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ABSTRACT: The influence of two water-leachable pore-forming agents, polyvinylpyrrolidone (PVP) and poly(ethylene glycol) (PEG), on the performance of cellulose acetate (CA) microporous membranes was elucidated. Various compositions of CA/PVP and CA/PEG blended membranes were prepared and characterized by Fourier transform infrared (FTIR) spectroscope and differential scanning calorimetry (DSC). The FTIR data indicated the presence of interaction between CA and pore-forming agent via a hydrogen bond. The DSC thermal data implied that CA and PEG presented as two separated phases in the blended membranes. However, CA and PVP were miscible at the blended compositions. The extent of miscibility between CA and pore-forming agents dominated the leach degree of the latter. The microporous membranes prepared by solvent–casting–leaching showed that PEG was completely leached from CA/PEG blended membranes regardless of its initial blending level. On the contrary, the leach of PVP was dependent of the initial composition of CA/PVP blended membranes. The permeation of theophylline from CA/PEG microporous membranes was much faster than from CA/PVP ones especially when blending 40–50% pore-forming agent. Although the porosities of CA50%/PVP50% and CA50%/PEG50% microporous membranes were similar, less tortuosity and more interconnected channels in terms of higher ɛ/τ value of CA50%/PEG50% microporous membrane resulted in the highest drug permeation. The permeation of theophylline through CA microporous membranes showed a good linear correlation with the ɛ/τ values of all microporous membranes (r2=0.994).Fuel and Energy Abstracts 05/2011; 373(1):189-195.