Absorption and emission cross-sections, Stark energy levels, and temperature dependent gain of Yb:QX phosphate glass.

We have obtained the absolute absorption cross-sections of Yb-doped phosphate QX laser glass at 300 K from 800-1100 nm, and generated the emission cross-sections via the standard method of reciprocity. By generating nine detailed high-confidence fitting functions for the absorption cross-sections, we then applied reciprocity to the individual absorption functions and obtain, for the first time to our knowledge, nine corresponding detailed emission functions that when summed, display a more accurate representation of the emission cross-sections as a function of wavelength than the standard method. A deeper mathematical understanding of reciprocity is also presented, along with derived Yb:QX Stark levels.

Genetic capitalism and stabilizing selection of antimicrobial resistance genotypes in Escherichia coli.

Antimicrobial resistance (AMR) in pathogenic strains of bacteria, such as Escherichia coli (E. coli), adversely impacts personal and public health. In this study, we examine competing hypotheses for the evolution of AMR including (i) 'genetic capitalism' in which genotypes that confer antibiotic resistance are gained and not often lost in lineages, and (ii) 'stabilizing selection' in which genotypes that confer antibiotic resistance are gained and lost often. To test these hypotheses, we assembled a dataset that includes annotations for 409 AMR genotypes and a phylogenetic tree based on genome-wide single nucleotide polymorphisms from 29 255 isolates of E. coli collected over the past 134 years. We used phylogenetic methods to count the times each AMR genotype was gained and lost across the tree and used model-based clustering of the genotypes with respect to their gain and loss rates. We demonstrate that many genotypes cluster to support the hypothesis for genetic capitalism while a few genotypes cluster to support the hypothesis for stabilizing selection. Comparing the sets of genotypes that fall under each of the hypotheses, we found a statistically significant difference in the breakdown of resistance mechanisms through which the AMR genotypes function. The result that many AMR genotypes cluster under genetic capitalism reflects that strong positive selective forces, primarily induced by human industrialization of antibiotics, outweigh the potential fitness costs to the bacterial lineages for carrying the AMR genotypes. We expect genetic capitalism to further drive bacterial lineages to resist antibiotics. We find that antibiotics that function via replacement and efflux tend to behave under stabilizing selection and thus may be valuable in an antibiotic cycling strategy.

Prostate cancer targeting motifs: expression of αν ß3, neurotensin receptor 1, prostate specific membrane antigen, and prostate stem cell antigen in human prostate cancer cell lines and xenografts.

BACKGROUND: Membrane receptors are frequent targets of cancer therapeutic and imaging agents. However, promising in vitro results often do not translate to in vivo clinical applications. To better understand this obstacle, we measured the expression differences in receptor signatures among several human prostate cancer cell lines and xenografts as a function of tumorigenicity. METHODS: Messenger RNA and protein expression levels for integrin α(ν) ß(3), neurotensin receptor 1 (NTSR1), prostate specific membrane antigen (PSMA), and prostate stem cell antigen (PSCA) were measured in LNCaP, C4-2, and PC-3 human prostate cancer cell lines and in murine xenografts using quantitative reverse transcriptase polymerase chain reaction, flow cytometry, and immunohistochemistry. RESULTS: Stable expression patterns were observed for integrin α(ν) and PSMA in all cells and corresponding xenografts. Integrin ß(3) mRNA expression was greatly reduced in C4-2 xenografts and greatly elevated in PC-3 xenografts compared with the corresponding cultured cells. NTSR1 mRNA expression was greatly elevated in LNCaP and PC-3 xenografts. PSCA mRNA expression was elevated in C4-2 xenografts when compared with C4-2 cells cultured in vitro. Furthermore, at the protein level, PSCA was re-expressed in all xenografts compared with cells in culture. CONCLUSIONS: The regulation of mRNA and protein expression of the cell-surface target proteins α(ν) ß(3), NTSR1, PSMA, and PSCA, in prostate cancer cells with different tumorigenic potential, was influenced by factors of the microenvironment, differing between cell cultures and murine xenotransplants. Integrin α(ν) ß(3), NTRS1 and PSCA mRNA expression increased with tumorigenic potential, but mRNA expression levels for these proteins do not translate directly to equivalent expression levels of membrane bound protein.

201 W picosecond green laser using a mode-locked fiber laser driven cryogenic Yb:YAG amplifier system.

We have generated 201 W of green (514.5 nm) average power from a frequency-doubled picosecond cryogenic Yb:YAG laser system driven by a 50 MHz, 12.4 ps mode-locked Yb fiber laser producing 430 W of average power at 1029 nm, using direct pulse amplification. The fundamental beam produced was near-diffraction-limited (M(2)<1.3). Second-harmonic-generation is achieved using a 20 mm long noncritically phase-matched Lithium triborate (LiB3O5) crystal; conversion efficiencies as high as 58% have been observed. At 100 W of 514.5 nm output power, the average M(2) value was 1.35. To the best of our knowledge, this is the highest average power picosecond green pulsed laser.

Ho:YAG absorption cross sections from 1700 to 2200 nm at 83, 175, and 295 K.

We have obtained absorption spectroscopic cross sections as a function of wavelength for the laser material Ho:YAG at 295, 175, and 83 K, in the spectral range from 1700 to 2200 nm. The absorption range corresponds to (5)I8-(5)I7 transitions from the ground state to the first excited state amenable to direct pumping by laser diodes and Tm fiber lasers. The data allow a direct comparison of the absorption cross-section intensities and linewidths as temperature is lowered from room temperature to cryogenic temperatures. Universal absorption curves and numerical tables are presented for pump sources that are assumed to have a gaussian spectral lineshape, as a function of center wavelength, bandwidth, and optical density (doping density×penetration depth), at 295 and 83 K. Curves and tables are presented for both 295 and 83 K and may be used to optimize the pump absorption and laser efficiency.

Phage display selection of cyclic peptides that inhibit Andes virus infection.

Specific therapy is not available for hantavirus cardiopulmonary syndrome caused by Andes virus (ANDV). Peptides capable of blocking ANDV infection in vitro were identified using antibodies against ANDV surface glycoproteins Gn and Gc to competitively elute a cyclic nonapeptide-bearing phage display library from purified ANDV particles. Phage was examined for ANDV infection inhibition in vitro, and nonapeptides were synthesized based on the most-potent phage sequences. Three peptides showed levels of viral inhibition which were significantly increased by combination treatment with anti-Gn- and anti-Gc-targeting peptides. These peptides will be valuable tools for further development of both peptide and nonpeptide therapeutic agents.

Heat-fraction-limited CW Yb:YAG cryogenic solid-state laser with 100% photon slope efficiency.

We report the demonstration of a heat-fraction-limited CW Yb:YAG laser operating near 77 K with output at 1029 nm, pumped with a diffraction-limited room-temperature CW Nd:YAG laser operating at 946 nm. With a 50% reflectivity outcoupler, the average threshold absorbed pump power was 18.8 mW and the average slope efficiency 91.9%, close to the heat-fraction limited value of 91.5%. Average optical to optical and photon slope efficiencies are 84% and 100% respectively. To the best of our knowledge this solid-state laser is the first to operate at the heat-fraction-limit and demonstrates record slope, photon slope and optical-optical efficiencies for optically-pumped solid-state lasers.

High sustained average power cw and ultrafast Yb:YAG near-diffraction-limited cryogenic solid-state laser.

We report what we believe to be record performance for a high average power Yb:YAG cryogenic laser system with sustained output power. In a CW oscillator-single-pass amplifier configuration, 963 W of output power was measured. In a second configuration, a two amplifier Yb:YAG cryogenic system was driven with a fiber laser picosecond ultrafast oscillator at a 50 MHz repetition rate, double-passed through the first amplifier and single-passed through the second, resulting in 758 W of average power output. Pulses exiting the system have a FWHM pulsewidth of 12.4 ps, an energy/pulse of 15.2 µJ, and a peak power of 1.23 MW. Both systems are force convection-cooled with liquid nitrogen and have been demonstrated to run reliably over long time periods.

Multivalent presentation of antihantavirus peptides on nanoparticles enhances infection blockade.

Viral entry into susceptible host cells typically results from multivalent interactions between viral surface proteins and host entry receptors. In the case of Sin Nombre virus (SNV), a New World hantavirus that causes hantavirus cardiopulmonary syndrome, infection involves the interaction between viral membrane surface glycoproteins and the human integrin alpha(v)beta(3). Currently, there are no therapeutic agents available which specifically target SNV. To address this problem, we used phage display selection of cyclic nonapeptides to identify peptides that bound SNV and specifically prevented SNV infection in vitro. We synthesized cyclic nonapeptides based on peptide sequences of phage demonstrating the strongest inhibition of infection, and in all cases, the isolated peptides were less effective at blocking infection (9.0% to 27.6% inhibition) than were the same peptides presented by phage (74.0% to 82.6% inhibition). Since peptides presented by the phage were pentavalent, we determined whether the identified peptides would show greater inhibition if presented in a multivalent format. We used carboxyl linkages to conjugate selected cyclic peptides to multivalent nanoparticles and tested infection inhibition. Two of the peptides, CLVRNLAWC and CQATTARNC, showed inhibition that was improved over that of the free format when presented on nanoparticles at a 4:1 nanoparticle-to-virus ratio (9.0% to 32.5% and 27.6% to 37.6%, respectively), with CQATTARNC inhibition surpassing 50% when nanoparticles were used at a 20:1 ratio versus virus. These data illustrate that multivalent inhibitors may disrupt polyvalent protein-protein interactions, such as those utilized for viral infection of host cells, and may represent a useful therapeutic approach.

The signature molecular descriptor. 3. Inverse-quantitative structure-activity relationship of ICAM-1 inhibitory peptides.

We present a methodology for solving the inverse-quantitative structure-activity relationship (QSAR) problem using the molecular descriptor called signature. This methodology is detailed in four parts. First, we create a QSAR equation that correlates the occurrence of a signature to the activity values using a stepwise multilinear regression technique. Second, we construct constraint equations, specifically the graphicality and consistency equations, which facilitate the reconstruction of the solution compounds directly from the signatures. Third, we solve the set of constraint equations, which are both linear and Diophantine in nature. Last, we reconstruct and enumerate the solution molecules and calculate their activity values from the QSAR equation. We apply this inverse-QSAR method to a small set of LFA-1/ICAM-1 peptide inhibitors to assist in the search and design of more-potent inhibitory compounds. Many novel inhibitors were predicted, a number of which are predicted to be more potent than the strongest inhibitor in the training set. Two of the more potent inhibitors were synthesized and tested in-vivo, confirming them to be the strongest inhibiting peptides to date. Some of these compounds can be recycled to train a new QSAR and develop a more focused library of lead compounds.

Optical and SPION-enhanced MR imaging shows that trans-stilbene inhibitors of NF-κB concomitantly lower Alzheimer's disease plaque formation and microglial activation in AßPP/PS-1 transgenic mouse brain.

Alzheimer's disease (AD) is associated with a microglia-dependent neuroinflammatory response against plaques containing the fibrous protein amyloid-ß (Aß). Activation of microglia, which closely associate with Aß plaques, engenders the release of pro-inflammatory cytokines and the internalization of Aß fibrils. Since the pro-inflammatory transcription factor NF-κB is one of the major regulators of Aß-induced inflammation, we treated transgenic amyloid-ß protein protein/presenilin-1 (AßPP/PS1) mice for one year with a low dose (0.01% by weight in the diet) of either of two trans-stilbene NF-κB inhibitors, resveratrol or a synthetic analog LD55. The 3D distribution of Aß plaques was measured ex vivo in intact brains at 60 µm resolution by quantitative magnetic resonance imaging (MRI) using blood-brain barrier-permeable, anti-AßPP-conjugated superparamagentic iron oxide nanoparticles (SPIONs). The MRI measurements were confirmed by optical microscopy of thioflavin-stained brain tissue sections and indicated that supplementation with either of the two trans-stilbenes lowered Aß plaque density in the cortex, caudoputamen, and hippocampus by 1.4 to 2-fold. The optical measurements also included the hippocampus and indicated that resveratrol and LD55 reduced average Aß plaque density by 2.3-fold and 3.1-fold, respectively. Ex vivo measurements of the regional distribution of microglial activation by Iba-1 immunofluorescence of brain tissue sections showed that resveratrol and LD55 reduced average microglial activation by 4.2- fold and 3.5-fold, respectively. Since LD55 lacked hydroxyl groups but both resveratrol and LD55 concomitantly reduced both Aß plaque burden and neuroinflammation to a similar extent, it appears that the antioxidant potential of resveratrol is not an important factor in plaque reduction.

SPION-enhanced magnetic resonance imaging of Alzheimer's disease plaques in AßPP/PS-1 transgenic mouse brain.

In our program to develop non-invasive magnetic resonance imaging (MRI) methods for the diagnosis of Alzheimer's disease (AD), we have synthesized antibody-conjugated, superparamagnetic iron oxide nanoparticles (SPIONs) for use as an in vivo agent for MRI detection of amyloid-ß plaques in AD. Here we report studies in AßPP/PS1 transgenic mice, which demonstrate the ability of novel anti-AßPP conjugated SPIONs to penetrate the blood-brain barrier to act as a contrast agent for MR imaging of plaques. The conspicuity of the plaques increased from an average Z-score of 5.1 ± 0.5 to 8.3 ± 0.2 when the plaque contrast to noise ratio was compared in control AD mice with AD mice treated with SPIONs. The number of MRI-visible plaques per brain increased from 347 ± 45 in the control AD mice, to 668 ± 86 in the SPION treated mice. These results indicated that our SPION enhanced amyloid-ß detection method delivers an efficacious, non-invasive MRI detection method in transgenic mice.

Prospective multicenter trial assessing effectiveness, refractive predictability and safety of a new aberration free, bi-aspheric intraocular lens.

PURPOSE: To determine the effectiveness and safety of the Softec HD IOL; and to present refractive outcomes for lenses manufactured at an IOL power tolerance of 0.11 D. METHODS: Three-hundred and ninety adult patients requiring removal of a cataractous lens with implantation of a monofocal IOL in at least one eye were eligible for study participation across eight US investigative sites. Patients were enrolled unilaterally. After routine surgery, subjects were examined for adverse events (AEs), best corrected visual acuity (BCVA) and manifest refraction correction at 12 months postoperatively. RESULTS: Three-hundred and sixty-six (95%) of patients completed the 12-month postoperative visit. The percent of patients achieving best corrected Snellen acuity 20/40 or better was 98.9%, and 81.1% of patients achieved best corrected Snellen acuity 20/25 or better. Of those patients (80%) implanted with a lens available in 0.25 D increments (manufactured at a tolerance of 0.11 D) 40.9%, 69.8% and 93.8% of patients were within ±0.25 D, ±0.50 D and ±1.0 D of predicted target refraction respectively. Overall incidence of cumulative and persistent IOL Grid AEs was 2.2% with no AE meeting or exceeding the FDA Grid of Historical Controls. CONCLUSIONS: The Softec HD IOL is a safe and effective lens. The high manufacturing tolerance of the lens appears to enhance refractive outcomes.

Immobilized stromal cell-derived factor-1alpha triggers rapid VLA-4 affinity increases to stabilize lymphocyte tethers on VCAM-1 and subsequently initiate firm adhesion.

The integrin VLA-4 (alpha(4)beta(1)) mediates tethering and rolling events as well as firm adhesion of leukocytes to VCAM-1. Unlike selectins, VLA-4 integrin-mediated lymphocyte adhesiveness can be modulated by chemokines through intracellular signaling pathways. To investigate the effects of the chemokine stromal cell-derived factor-1alpha (SDF-1alpha) on VLA-4-mediated lymphocyte adhesion, human PBL were flowed over VCAM-1 substrates in a parallel plate flow chamber with surface-immobilized SDF-1alpha, a potent activator of firm adhesion. The initial tethering interactions had a median lifetime of 200 ms, consistent with the half-life of low-affinity VLA-4-VCAM-1 bonds. Immobilized SDF-1alpha acted within the lifetime of a primary tether to stabilize initial tethering interactions, increasing the likelihood a PBL would remain interacting with the surface. As expected, the immobilized SDF-1alpha also increased the ratio of PBL firm adhesion to rolling. An LDV peptide-based small molecule that preferentially binds high-affinity VLA-4 reduced PBL firm adhesion to VCAM-1 by 90%. The reduction in firm adhesion due to blockage of high-affinity VLA-4 was paralleled by a 4-fold increase in the fraction of rolling PBL. Chemokine activation of PBL firm adhesion on VCAM-1 depended on induction of high-affinity VLA-4 rather than recruitment of a pre-existing pool of high-affinity VLA-4 as previously thought.

Peptide antagonists that inhibit Sin Nombre virus and hantaan virus entry through the beta3-integrin receptor.

Specific therapy is not available for the treatment of hantavirus cardiopulmonary syndrome caused by Sin Nombre virus (SNV). The entry of pathogenic hantaviruses into susceptible human cells is dependent upon expression of the alpha(v)beta(3) integrin, and transfection of human beta(3) integrin is sufficient to confer infectibility onto CHO (Chinese hamster ovary) cells. Furthermore, pretreatment of susceptible cells with anti-beta(3) antibodies such as c7E3 or its Fab fragment ReoPro prevents hantavirus entry. By using repeated selection of a cyclic nonamer peptide phage display library on purified alpha(v)beta(3), we identified 70 peptides that were competitively eluted with ReoPro. Each of these peptides was examined for its ability to reduce the number of foci of SNV strain SN77734 in a fluorescence-based focus reduction assay according to the method of Gavrilovskaya et al. (I. N. Gavrilovskaya, M. Shepley, R. Shaw, M. H. Ginsberg, and E. R. Mackow, Proc. Natl. Acad. Sci. USA 95:7074-7079, 1998). We found that 11 peptides reduced the number of foci to a greater extent than did 80 mug/ml ReoPro when preincubated with Vero E6 cells. In addition, 8 of the 70 peptides had sequence similarity to SNV glycoproteins. We compared all 18 peptide sequences (10 most potent, 7 peptides with sequence similarity to hantavirus glycoproteins, and 1 peptide that was in the group that displayed the greatest potency and had significant sequence similarity) for their abilities to inhibit SNV, Hantaan virus (HTNV), and Prospect Hill virus (PHV) infection. There was a marked trend for the peptides to inhibit SNV and HTNV to a greater extent than they inhibited PHV, a finding that supports the contention that SNV and HTNV use beta(3) integrins and PHV uses a different receptor, beta1 integrin. We then chemically synthesized the four peptides that showed the greatest ability to neutralize SNV. These peptides inhibited viral entry in vitro as free peptides outside of the context of a phage. Some combinations of peptides proved more inhibitory than did individual peptides. In all, we have identified novel peptides that inhibit entry by SNV and HTNV via beta(3) integrins and that can be used as lead compounds for further structural optimization and consequent enhancement of activity.

Regulation of human basophil adhesion to endothelium under flow conditions: Different very late antigen 4 regulation on umbilical cord blood-derived and peripheral blood basophils.

BACKGROUND: Although soluble mediators released by basophils in tissue sites contribute to the chronic injury that occurs in hypersensitivity diseases, only limited information is available about how circulating basophils are recruited to tissues. In particular, the interaction of basophils with endothelium under conditions that mimic physiologic flow has not been explored. OBJECTIVE: We sought to identify adhesion molecules regulating the attachment of human basophils to IL-4-activated human umbilical vein endothelial cells (HUVECs) under flow conditions. METHODS: A parallel-plate flow chamber and blocking mAbs were used to define the adhesion molecules involved in the interactions of peripheral blood basophils (PBBs) and cord blood-derived basophils (CBDBs) with IL-4-activated HUVECs and with Chinese hamster ovary (CHO) cell transfectants expressing specific adhesion molecules. A fluorescent ligand specific for very late antigen 4 (VLA-4) was used to directly examine the VLA-4 affinity state of basophils. RESULTS: Flowing PBBs and CBDBs attached to activated HUVECs and to CHO cells expressing P- or E-selectin. However, only CBDBs attached to vascular cell adhesion molecule 1 (VCAM-1)-transfected CHO cells under flow conditions. The attachment of CBDBs to CHO cells was blocked by mAbs directed against E-selectin, P-selectin, and VCAM-1, whereas attachment of PBBs was blocked by E-selectin and P-selectin mAbs. Activating VLA-4 with Mn(2+) on PBBs resulted in adhesion to the VCAM-1-transfected CHO cells, indicating that VLA-4 activity on PBBs can be regulated, at least in part, through affinity changes. The Mn(2+)-induced upregulation of basophil VLA-4 affinity was demonstrated directly by using a fluorescent ligand for VLA-4 and flow cytometry. CONCLUSIONS: The interaction of human CBDBs and PBBs with endothelium under flow conditions is mediated in part by both P- and E-selectin. VLA-4 additionally contributes to the adhesion of flowing CBDBs. However, the affinity of VLA-4 is too low to support the adhesion under flow conditions of unstimulated PBBs.