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Detailed functional comparison of three isoforms of the sodium-calcium exchanger, NX1, NX2 and NX3, was undertaken to gain insight on the functional properties of these enzymes. These isoforms were cloned and expressed in transfected BHK cells. Whole cell, vesicle and patch clamp analyses under different ionic regimes revealed that the three isoforms have very similar ionic affinities, pH and chymotrypsin sensitivity and inhibitor response. All three isoforms are regulated by intracellular calcium concentration.

Abstract Developing new vaccination strategies and optimizing current vaccines through heterologous prime-boost carries the promise of integrating the benefits of different yet synergistic vectors. It has been widely thought that the increased immunity afforded by heterologous prime-boost vaccination is mainly due to the minimization of immune responses to the carrier vectors, which allows a progressive build up of immunity against defined epitopes and the subsequent induction of broader immune responses against pathogens. Focusing on CD8+ T cells, we put forward a different yet complementary hypothesis based primarily on the systematic analysis of DNA vaccines as priming agents. This hypothesis relies on the finding that during the initiation of immune response, acquisition of co-inhibitory receptors such as programmed cell death-1 (PD-1) is determined by the pattern of antigen exposure in conjunction with Toll-like receptor (TLR)-dependent stimulation, critically affecting the magnitude and profile of secondary immunity. This hypothesis, based upon the acquisition and co-regulation of pivotal inhibitory receptors by CD8+ T cells, offers a rationale for gene-based immunization as an effective priming strategy and, in addition, outlines a new dimension to immune homeostasis during immune reaction to pathogens. Finally, this model implies that new and optimized immunization approaches for cancer and certain viral infections must induce highly efficacious T cells, refractory to a broad range of immune-inhibiting mechanisms, rather than solely or primarily focusing on the generation of large pools of vaccine-specific lymphocytes.

Enhanced light transmission through coupling incident light with surface plasmon polaritons (SPPs) on a layer-plus-islands nanostructure Ag layer, surrounded by symmetric ZnO dielectrics (ZnO/Ag/ZnO), was investigated. The couple and decouple processes at ZnO/Ag and Ag/ZnO grating interfaces were considered to confine the incident light to SPPs (near field) and then to excite the SPPs to radiate light (far field), which enhanced light transmission. A broad range of light transmission enhancement showed a blueshift with increasing Ag midlayer mass thickness. The physical reasons for light transmission enhancement were theoretically discussed using both the metal/dielectric grating interface model and the Drude–Lorentz free electron model. [ABSTRACT FROM AUTHOR]

It is known that the ac electrodeposition method with low current density can grow compact metal nanowires, but the length of those nanowires is very short. In contrast, the ac electrodeposition method with high current density can grow long metal nanowires. However these long nanowires are not compact and contain lots of defects. In this paper, we describe a multistep ac electrodeposition method to fabricate long metal nanowires with compact structure uniformly filled upon a porous anodic aluminum oxide template. Using this method, Co nanowires with high coercivity (Hc∥) and remnant ratio (Mr/Ms) have been prepared under relatively low deposition current density. The Co nanowires exhibited obvious magnetic anisotropy with the easy axis along the axial direction of nanowires. The maximal Hc∥ (2900 Oe) and Mr/Ms (0.95) were optimal for the perpendicular magnetic recording materials. The magnetic microstructure of Co nanowires is also discussed in this paper. [ABSTRACT FROM AUTHOR]

Experiments were conducted in a parallel-plate channel in which an extremely dilute suspension of heavy, positively polarized spheres was exposed to an ac electric field under conditions such that the field lines were arranged in the channel cross section perpendicular to the streamlines of the main flow. To reduce the effects of the gravitational settling of the particles, the channel was slowly rotated around a horizontal axis. Following the application of a high-gradient strong ac field (∼ several kV/mm), the particles were found to move towards both the high-voltage and grounded electrodes and to form arrays of "bristles" along their edges. The process was also modeled theoretically by computing the trajectories of individual particles under the action of dielectrophoretic, viscous, and gravitational forces and under conditions of negligibly small particle Reynolds numbers. The model calculations required no fitting parameters because the particle polarizability was determined independently by measuring the frequency and concentration dependence of the complex dielectric permittivity of a suspension in a low-strength field (∼ V/mm). The predictions of this model were found to be consistent with the experimental data for the rate of particle accumulation on the electrodes but not for the aggregation pattern which, even for initially extremely dilute suspensions, appeared to be governed by the interparticle interactions and to be created by a two-step mechanism. The results of our studies provide the basic characteristics of the field-induced particle motions and segregation needed for the design and optimization of electrohydrodynamic apparatuses. [ABSTRACT FROM AUTHOR]

In a revised topological model of the cardiac [Na.sup.+]-[Ca.sup.2+] exchanger, the exchanger contains nine transmembrane segments (TMSs) and two possible re-entrant loops. The TMSs form two clusters separated by a large intracellular loop (loop f) between TMS5 and TMS6. We have combined cysteine mutagenesis and oxidative crosslinking to study proximity relationships of TMSs in the exchanger. Pairs of cysteines were reintroduced into a cysteine-less exchanger, one in a TMS in the [NH.sub.2]-terminal cluster (TMSs 1-5) and the other in a TMS in the COOH-terminal cluster (TMSs 6-9). The mutant exchanger proteins were expressed in HEK293 cells and disulfide bond formation between introduced cysteines was analyzed by gel mobility shifts (Philipson et al. 1988. Biochim. Biophys. Acta. 945:298-306). Western blots showed that S117C/V804C, A122C/Y892C, C151/T815C, and C151/A821C mutant proteins migrated to 120 kD under reducing conditions and displayed a partial mobility shift to 160 kD under nonreducing conditions. This indicates the formation of a partial disulfide bond between these paired cysteine residues. Cu-phenanthroline and crosslinker o-PDM enhanced the mobility shift to 160 kD. Our data suggest that TMS7 is close to TMS3 near the intracellular side of the membrane and is in the vicinity of TMS2 at the extracellular end of the helices. Also, TMS2 must adjoin TMS8. This initial packing model of the exchanger also brings two functionally important domains in the exchanger, the ([Alpha]1- and [Alpha]2-repeats, close to each other. Mutant proteins C151/ T815C and C151/A821C had increased activities when analyzed using a whole-cell [sup.45]Ca uptake assay. The inter-TMS disulfide bond formation between TMS3 and TMS7 may facilitate a more active conformation for ion transport. (Supported by NIH grant HL-49101 and a grant from American Heart Association, Western States Affiliate.)