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Biomedical subjects

P Alexander

Publications and source records attributed to P Alexander.

241 records · Page 14Linked to original sources
PubMedDate not supplied

Regulation of apoptosis by presenilin 1.

Familial Alzheimer's disease is transmitted as an autosomal dominant disorder and, in 5-10% of the cases, is caused by mutations in the coding regions of two homologous genes, Presenilin 1 and 2 (PS1 and PS2). Previously, we have shown that PS2, a homolog of PS1. regulates apoptosis induced in neurons by trophic withdrawal or Abeta, and in T-cells by Fas ligand. We now report that PS1 also regulates apoptosis. Both wild-type and the H115Y mutant form of PS1 enhance Fas-mediated apoptosis in Jurkat cells. We also observed that wild-type and the H115Y mutant form of PS1 differentially regulate Jun Kinase, an important enzyme regulating apoptosis.

Aging↗
PubMedDate not supplied

In situ magnetic resonance measurement of conversion, hydrodynamics and mass transfer during single- and two-phase flow in fixed-bed reactors.

In recent years there has been increasing interest in applying magnetic resonance (MR) techniques in areas of engineering and chemical technology. The science that underpins many of these applications is the physics and chemistry of transport and reaction processes in porous materials. Key to the exploitation of MR methods will be our ability to demonstrate that MR yields information that cannot be obtained using conventional measurement techniques in engineering research. This article describes two case studies that highlight the power of MR to give new insights to chemical engineers. First, we demonstrate the application of MR techniques to explore both mass transfer and chemical conversion in situ within a fixed bed of catalyst, and we then use these data to identify the rate-controlling step of the chemical conversion. Second, we implement a rapid imaging technique to study the stability of the gas-liquid distribution in the low- and high-interaction two-phase flow regimes in a trickle-bed reactor.

Acetic Acid↗
PubMedDate not supplied

Characterisation of fluid flow through porous media using three-dimensional microimaging and pulsed gradient stimulated echo NMR.

Pulsed gradient stimulated echo (PGSTE) and microimaging nuclear magnetic resonance (NMR) are used to probe correlations between structure and flow in the void space of a model porous system formed from a packing of 1-mm diameter glass spheres. The pulsed gradient stimulated echo data determine the average propagator and permit the dispersion of the flow to be studied as a function of delay time. Microimaging yields structural information and, specifically, a reduced radial distribution function (rdf) for the structure of the void space. Transition to fully developed dispersive flow is shown to occur on a scale size for which no further correlations in the structure of the void space are observed.

Glass↗
PubMedDate not supplied

Visualisation of structure and flow in packed beds.

Magnetic resonance imaging (MRI) volume- and velocity-measurement techniques are used to probe structure-flow correlations within the interparticle space of a packed bed of ballotini. Images of the three mutually orthogonal components of the velocity field are obtained in axial and radial image slices within a bed of 5-mm-diameter ballotini, packed within a glass column of internal diameter 4.6 cm. A three-dimensional volume image of the bed is also obtained and analysed to partition the interparticle space into individual pores and determine the location of pore necks. Significant heterogeneity in the flow is observed; in one slice approximately 8% of the pores carry 40% of the volume flow. The characteristics of pores carrying anomalously high values of fluid flow rate and velocity are investigated.

Humans↗
PubMedDate not supplied

Moving cemeteries: a framework for facilitating curriculum revision.

The process of revising a nursing curriculum can be accompanied by self-oriented faculty behaviors such as inflexibility, indifference, and territoriality. The authors, who served as members of a curriculum revision task force, suggest the need for planned, intentional, and goal-directed approaches when revising an academic program. Lancaster's six components of research by committee are used as a framework to offer insights for enhancing.

Communication↗