Biochemical and Molecular Characterization of Proteoglycans in the Chick Nervous System

The nervous system contains hundreds of different cell-types which arise in a precise temporal and spatial developmental pattern. The complex pattern of neural development is characterized by a distinct series of events, which include cell proliferation, migration, differentiation, neurite extension, and synaptagenesis (Jacobson, 1978). Proteoglycans have been implicated in being involved in many of these processes, but have been poorly characterized in the developing vertebrate nervous system (Margolis and Margolis, 1989a; 1989b; 1993; Herndon and Lander, 1989). The studies outlined in this thesis have focussed on the identification, biochemical characterization, and developmental regulation of the major proteoglycan species in the developing chick nervous system. This analysis has provided insight into the different functions mediated by nervous system HSPGs and CSPGs\KSPGs, and have enabled us to produce specific proteoglycan antisera that can be used to elucidate specific proteoglycan functions. We have also described the molecular cloning, sequence analysis, and in situ mRNA localization, of a nervous system keratan sulfate proteoglycan, claustrin. These analyses have determined that claustrin is highly homologous to the mouse MAP1B protein, and furthermore, suggest that MAP1B itself may be a keratan sulfate proteoglycan. In situ localization of claustrin mRNA during chick development has reinforced previous studies (Cole and McCabe, 1991; McCabe and Cole, 1992; McCabe et al, 1991) suggesting that claustrin may be an inhibitory growth molecule localized to many of the proposed glial barrier structures in the developing chick CNS

Pericardial Cyst: Unexpected Finding on a Chest Radiograph

<p>[West J Emerg Med. 2011;12(4):579–580.]</p

Continuous Diaphragm Sign

<p>[West J Emerg Med. 2011;12(4):526–527.]</p

The Phase Space and Stellar Populations of Cluster Galaxies at z ~ 1: Simultaneous Constraints on the Location and Timescale of Satellite Quenching

We investigate the velocity vs. position phase space of z ~ 1 cluster galaxies using a set of 424 spectroscopic redshifts in 9 clusters drawn from the GCLASS survey. Dividing the galaxy population into three categories: quiescent, star-forming, and poststarburst, we find that these populations have distinct distributions in phase space. Most striking are the poststarburst galaxies, which are commonly found at small clustercentric radii with high clustercentric velocities, and appear to trace a coherent ``ring" in phase space. Using several zoom simulations of clusters we show that the coherent distribution of the poststarbursts can be reasonably well-reproduced using a simple quenching scenario. Specifically, the phase space is best reproduced if satellite quenching occurs on a rapid timescale (0.1 < tau_{Q} < 0.5 Gyr) after galaxies make their first passage of R ~ 0.5R_{200}, a process that takes a total time of ~ 1 Gyr after first infall. We compare this quenching timescale to the timescale implied by the stellar populations of the poststarburst galaxies and find that the poststarburst spectra are well-fit by a rapid quenching (tau_{Q} = 0.4^{+0.3}_{-0.4} Gyr) of a typical star-forming galaxy. The similarity between the quenching timescales derived from these independent indicators is a strong consistency check of the quenching model. Given that the model implies satellite quenching is rapid, and occurs well within R_{200}, this would suggest that ram-pressure stripping of either the hot or cold gas component of galaxies are the most plausible candidates for the physical mechanism. The high cold gas consumption rates at z ~ 1 make it difficult to determine if hot or cold gas stripping is dominant; however, measurements of the redshift evolution of the satellite quenching timescale and location may be capable of distinguishing between the two.Comment: 10 pages, 4 figures, submitted to the Ap

Dual-Source CT Angiography of Peripheral Arterial Stents: In Vitro Evaluation of 22 Different Stent Types

Purpose. To test different peripheral arterial stents using four image reconstruction approaches with respect to lumen visualization, lumen attenuation and image noise in dual-source multidetector row CT (DSCT) in vitro. Methods and Materials. 22 stents (nitinol, steel, cobalt-alloy, tantalum, platinum alloy) were examined in a vessel phantom. All stents were imaged in axial orientation with standard parameters. Image reconstructions were obtained with four different convolution kernels. To evaluate visualization characteristics of the stent, the lumen diameter, intraluminal density and noise were measured. Results. The mean percentage of the visible stent lumen diameter from the nominal stent diameter was 74.5% ± 5.7 for the medium-sharp kernel, 72.8% ± 6.4 for the medium, 70.8% ± 6.4 for the medium-smooth and 67.6% ± 6.6 for the smooth kernel. Mean values of lumen attenuation were 299.7HU ± 127 (medium-sharp), 273.9HU ± 68 (medium), 270.7HU ± 53 (medium-smooth) and 265.8HU ± 43. Mean image noise was: 54.6 ± 6.3, 20.5 ± 1.7, 16.3 ± 1.7, 14.0 ± 2 respectively. Conclusion. Visible stent lumen diameter varies depending on stent type and scan parameters. Lumen diameter visibility increases with the sharpness of the reconstruction kernel. Smoother kernels provide more realistic density measurements inside the stent lumen and less image noise