University of California, Irvine

About: University of California, Irvine is a education organization based out in Irvine, California, United States. It is known for research contribution in the topics: Population & Galaxy. The organization has 47031 authors who have published 113602 publications receiving 5521832 citations. The organization is also known as: UC Irvine & UCI.

Humanized xenobiotic response in mice expressing nuclear receptor SXR.

Abstract: The cytochrome CYP3A gene products, expressed in mammalian liver, are essential for the metabolism of lipophilic substrates, including endogenous steroid hormones and prescription drugs. CYP3A enzymes are extremely versatile and are inducible by many of their natural and xenobiotic substrates. Consequently, they form the molecular basis for many clinical drug-drug interactions. The induction of CYP3A enzymes is species-specific, and we have postulated that it involves one or more cellular factors, or receptor-like xeno-sensors. Here we identify one such factor unequivocally as the nuclear receptor pregnenolone X receptor (PXR) and its human homologue, steroid and xenobiotic receptor (SXR). We show that targeted disruption of the mouse PXR gene abolishes induction of CYP3A by prototypic inducers such as dexamethasone or pregnenolone-16alpha-carbonitrile. In transgenic mice, an activated form of SXR causes constitutive upregulation of CYP3A gene expression and enhanced protection against toxic xenobiotic compounds. Furthermore, we show that the species origin of the receptor, rather than the promoter structure of CYP3A genes, dictates the species-specific pattern of CYP3A inducibility. Thus, we can generate 'humanized' transgenic mice that are responsive to human-specific inducers such as the antibiotic rifampicin. We conclude that SXR/PXR genes encode the primary species-specific xeno-sensors that mediate the adaptive hepatic response, and may represent the critical biochemical mechanism of human xenoprotection.

Measurement of neutrino oscillation by the K2K experiment

Abstract: We present measurements of {nu}{sub {mu}} disappearance in K2K, the KEK to Kamioka long-baseline neutrino oscillation experiment. One-hundred and twelve beam-originated neutrino events are observed in the fiducial volume of Super-Kamiokande with an expectation of 158.1{sub -8.6}{sup +9.2} events without oscillation. A distortion of the energy spectrum is also seen in 58 single-ring muonlike events with reconstructed energies. The probability that the observations are explained by the expectation for no neutrino oscillation is 0.0015% (4.3{sigma}). In a two-flavor oscillation scenario, the allowed {delta}m{sup 2} region at sin{sup 2}2{theta}=1 is between 1.9 and 3.5x10{sup -3} eV{sup 2} at the 90% C.L. with a best-fit value of 2.8x10{sup -3} eV{sup 2}.

One thousand health-related quality-of-life estimates.

Abstract: Objective.Analysts performing cost-effectiveness analyses often do not have the resources to gather original quality-of-life (QOL) weights. Furthermore, variability in QOL for the same health state hampers the comparability of cost-effectiveness analyses. For these reasons, opinion leaders such as t

Dependence of carrier mobility on nanocrystal size and ligand length in PbSe nanocrystal solids.

Abstract: We measure the room-temperature electron and hole field-effect mobilities (μFE) of a series of alkanedithiol-treated PbSe nanocrystal (NC) films as a function of NC size and the length of the alkane chain. We find that carrier mobilities decrease exponentially with increasing ligand length according to the scaling parameter β = 1.08−1.10 A−1, as expected for hopping transport in granular conductors with alkane tunnel barriers. An electronic coupling energy as large as 8 meV is calculated from the mobility data. Mobilities increase by 1−2 orders of magnitude with increasing NC diameter (up to 0.07 and 0.03 cm2 V−1 s−1 for electrons and holes, respectively); the electron mobility peaks at a NC size of ∼6 nm and then decreases for larger NCs, whereas the hole mobility shows a monotonic increase. The size-mobility trends seem to be driven primarily by the smaller number of hops required for transport through arrays of larger NCs but may also reflect a systematic decrease in the depth of trap states with decre...

Introduction to Theoretical Kinematics

Abstract: "Introduction to Theoretical Kinematics" provides a uniform presentation of the mathematical foundations required for studying the movement of a kinematic chain that makes up robot arms, mechanical hands, walking machines, and similar mechanisms It is a concise and readable introduction that takes a more modern approach than other kinematics texts and introduces several useful derivations that are new to the literature The author employees a unique format, highlighting the similarity of the mathematical results for planar, spherical, and spatial cases by studying them all in each chapter rather than as separate topics For the first time, he applies to kinematic theory two tools of modern mathematics--the theory of multivectors and the theory of Clifford algebras--that serve to clarify the seemingly arbitrary nature of the construction of screws and dual quaternions The first two chapters formulate the matrices that represent planar, spherical, and spatial displacements and examine a continuous set of displacements which define a continuous movement of a body, introducing the "tangent operator" Chapter 3 focuses on the tangent operators of spatial motion as they are reassembled into six-dimensional vectors or screws, placing these in the modern setting of multivector algebra Clifford algebras are used in chapter 4 to unify the construction of various hypercomplex "quaternion" numbers Chapter 5 presents the elementary formulas that compute the degrees of freedom, or mobility, of kinematic chains, and chapter 6 defines the structure equations of these chains in terms of matrix transformations The last chapter computes the quaternion form ofthe structure equations for ten specific mechanisms These equations define parameterized manifolds in the Clifford algebras, or "image spaces," associated with planar, spherical, and spatial displacements McCarthy reveals a particularly interesting result by showing that these parameters can be mathematically manipulated to yield hyperboloids or intersections of hyperboloids