32 research outputs found

    Plasma protein binding of prednisolone in normal volunteers and arthritic patients

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    The plasma binding of prednisolone was studied in twenty normal volunteers and twenty rheumatoid arthritis patients. An in vitro assessment of the binding following the addition of prednisolone, prednisone, and hydrocortisone to the plasmas obtained from the subjects showed significant differences in the percentage of prednisolone bound. However, the differences observed were regarded as clinically insignificant. The plasma protein binding was determined by an in vitro equilibrium dialysis of the individual plasma samples at 37° C. Prednisolone levels on both sides of the dialysis membrane were determined using radioactivity and HPLC analytical methodologies. The percentages of prednisolone bound calculated from the analytical results of either the radiochemical or HPLC method were not significantly different. The change in the percentage of prednisolone bound to plasma proteins was studied as a function of the total prednisolone plasma concentration in a normal volunteer and in a systemic lupus erythematosis patient. As a result of prednisolone binding to both transcortin and albumin, the binding of prednisolone changes as a function of prednisolone concentration. The binding data were fitted using nonlinear least squares regression, and the affinity constants for the binding of prednisolone to transcortin and albumin were estimated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46638/1/228_2004_Article_BF00568200.pd

    Cytochromes P450 in the biocatalytic valorization of lignin

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    The valorization of lignin is critical to establishing sustainable biorefineries as we transition away from petroleum-derived feedstocks. Advances in lignin fractionation and depolymerization are yielding new opportunities for the biocatalytic upgrading of lignin-derived aromatic compounds (LDACs) using microbial cell factories. Given their roles in lignin metabolism and their catalytic versatility, cytochromes P450 are attractive enzymes in engineering such biocatalysts. Here we highlight P450s that catalyze aromatic O-demethylation, a rate-limiting step in the conversion of LDACs to valuable chemicals, including efforts to engineer the specificity of these enzymes and to use them in developing biocatalysts. We also discuss broader opportunities at the intersection of biochemistry, structure-guided enzyme engineering, and metabolic engineering for application of P450s in the emerging area of microbial lignin valorization.Science, Faculty ofNon UBCMicrobiology and Immunology, Department ofReviewedFacultyResearcherGraduat

    Anisotropic scattering kernel: Generalized and modified Maxwell boundary conditions

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    This paper presents a model of a scattering kernel of boundary conditions for the Boltzmann equation. The proposed scattering kernel is based on an anisotropic accommodation argument. Three parameters equal to the momentum accommodation coeffcients are shown as characterizing the influence of each direction. First the new scattering kernel is derived from a phenomenological criticism of the first form of the scattering kernel proposed by Maxwell; then the same result is established from an analytic approach based on the spectral nature of the linear integral operator associated to the scattering kernel problem. As a result, the model provides a correct form of scattering kernel to handle the influence of each direction in particle collisions with the wall. Finally independent accommodation of each internal mode is added to extend the model to the case of polyatomic gases
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