\u3cem\u3eDe Novo\u3c/em\u3e [PSI\u3csup\u3e+\u3c/sup\u3e] Prion Formation Involves Multiple Pathways to Form Infectious Oligomers

Prion and other neurodegenerative diseases are associated with misfolded protein assemblies called amyloid. Research has begun to uncover common mechanisms underlying transmission of amyloids, yet how amyloids form in vivo is still unclear. Here, we take advantage of the yeast prion, [PSI +], to uncover the early steps of amyloid formation in vivo. [PSI +] is the prion form of the Sup35 protein. While [PSI +] formation is quite rare, the prion can be greatly induced by overexpression of the prion domain of the Sup35 protein. This de novo induction of [PSI +] shows the appearance of fluorescent cytoplasmic rings when the prion domain is fused with GFP. Our current work shows that de novoinduction is more complex than previously thought. Using 4D live cell imaging, we observed that fluorescent structures are formed by four different pathways to yield [PSI +] cells. Biochemical analysis of de novo induced cultures indicates that newly formed SDS resistant oligomers change in size over time and lysates made from de novo induced cultures are able to convert [psi −] cells to [PSI +] cells. Taken together, our findings suggest that newly formed prion oligomers are infectious

Degenerate Sectors of the Ashtekar Gravity

This work completes the task of solving locally the Einstein-Ashtekar equations for degenerate data. The two remaining degenerate sectors of the classical 3+1 dimensional theory are considered. First, with all densitized triad vectors linearly dependent and second, with only two independent ones. It is shown how to solve the Einstein-Ashtekar equations completely by suitable gauge fixing and choice of coordinates. Remarkably, the Hamiltonian weakly Poisson commutes with the conditions defining the sectors. The summary of degenerate solutions is given in the Appendix.Comment: 19 pages, late

Lateral grating DFB AlGaInN laser diodes for optical communications and atomic clocks

AlGaInN laser diode technology is of considerable interest for telecom applications and next generation atomic optical clocks based on Sr (by using 422nm & 461nm) and Rb at 420.2nm.Very narrow linewidths (<1MHz) are required for such applications. We report lateral gratings on AlGaInN ridge waveguide laser diodes to achieve a single wavelength device with a good side mode suppression ratio (SMSR) that is suitable for atomic clock and telecom applications

Influence of low-level Pr substitution on the superconducting properties of YBa2Cu3O7-delta single crystals

We report on measurements on Y1-xPrxBa2Cu3O7-delta single crystals, with x varying from 0 to 2.4%. The upper and the lower critical fields, Hc2 and Hc1, the Ginzburg-Landau parameter and the critical current density, Jc(B), were determined from magnetization measurements and the effective media approach scaling method. We present the influence of Pr substitution on the pinning force density as well as on the trapped field profiles analyzed by Hall probe scanning.Comment: 4 pages, 5 figures, accepted for publication in J. Phys. Conf. Se

Near-infrared line identification in type Ia supernovae during the transitional phase

We present near-infrared synthetic spectra of a delayed-detonation hydrodynamical model and compare them to observed spectra of four normal type Ia supernovae ranging from day +56.5 to day +85. This is the epoch during which supernovae are believed to be undergoing the transition from the photospheric phase, where spectra are characterized by line scattering above an optically thick photosphere, to the nebular phase, where spectra consist of optically thin emission from forbidden lines. We find that most spectral features in the near-infrared can be accounted for by permitted lines of Fe II and Co II. In addition, we find that [Ni II] fits the emission feature near 1.98 {\mu}m, suggesting that a substantial mass of 58Ni exists near the center of the ejecta in these objects, arising from nuclear burning at high density. A tentative identification of Mn II at 1.15 {\mu}m may support this conclusion as well.Comment: accepted to Ap

"Evaluation of high-dose estrogen and high-dose estrogen plus methyltestosterone treatment on cognitive task performance in postmenopausal women"

Amy B. Wisniewski is an Assistant Professor of Biology at Drake University, Des Moines, Iowa. She can be contacted at [email protected]: To investigate the cognitive effects of high-dose oral estrogen alone or in combination with oral methyltestosterone in postmenopausal women. Methods: Participants were tested with a randomized, double-blind design on the Identical Pictures, Cube Comparisons, Building Memory and Shape Memory tasks before and after 4 months of hormone treatment. Results: Women receiving estrogen and methyltestosterone maintained a steady level of performance on the Building Memory task, whereas those receiving estrogen alone showed a decrease in performance. Conclusions: These results indicate that the addition of testosterone to high-dose estrogen replacement exerts a protective effect on memory performance in postmenopausal women. Copyright © 2002 S. Karger AG, Basel.Portions of this manuscript were presented at the 1999 Endocrine Society Meeting, San Diego, Calif., USA and the 1999 North American Menopause Society Meeting, New York, N.Y., USA This research was partially supported by the Johns Hopkins University School of Medicine General Clinical Research Center, NIH/NCRR grant M01 RR00052. This research was also funded in part by Solvay Pharmaceuticals, Inc., Marietta, Ga., USA