170 research outputs found

    Ultrafast (“Quasi-Static”) Quenching of Trp in Proteins and Peptides

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    COMPARATIVE PRODUCER COSTS OF GAP AND GHP STANDARDS: CAN THE PLAYING FIELD BE MADE LEVEL?

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    A number of microbial contamination incidents have continued to raise questions regarding the safety of the U.S. food supply with calls for improved food safety control initiatives and standards by both the private and public sectors. As a reaction to these incidents, there have been increased efforts to enhance food safety by the government and industry groups. Increasingly, process standards are being specified that recommend or prescribe Good Agricultural Practices (GAP) standards for production, Good Handling Practices (GHP) standards for handling products, and Good Management Practices (GMP) for responsibilities in overseeing production and handling operations. A primary concern is the potential that the costs associated with implementing food safety related standards will prohibit small producers and handlers from taking part in certain market segments, such as supplying the supermarkets that sell most of the production in developed and more advanced developing countries. Previous study results are presented that suggest economies of scale effects for larger farm size operations leading to lower per-unit compliance cost. This analysis utilized specialty crop representative farm stochastic simulation models that were designed to analyze the impacts of current and changing market conditions and government policies on a number of key operating variables (KOV). The results of the analysis provide an initial indication that the cost associated with compliance to regulatory standards does have an effect on the profitability of individual enterprises.Food safety, citrus, fresh produce, and regulatory costs, Agricultural and Food Policy, Consumer/Household Economics, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, Health Economics and Policy, Q12,

    FRET microscopy autologous tumor lysate processing in mature dendritic cell vaccine therapy

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    Abstract Background: Antigen processing by dendritic cells (DC) exposed to specific stimuli has been well characterized in biological studies. Nonetheless, the question of whether autologous whole tumor lysates (as used in clinical trials) are similarly processed by these cells has not yet been resolved. Methods: In this study, we examined the transfer of peptides from whole tumor lysates to major histocompatibility complex class II molecules (MHC II) in mature dendritic cells (mDC) from a patient with advanced melanoma. Tumor antigenic peptides-MHC II proximity was revealed by F\uf6rster Resonance Energy Transfer (FRET) measurements, which effectively extends the application of fluorescence microscopy to the molecular level (<100?). Tumor lysates were labelled with Alexa-488, as the donor, and mDC MHC II HLA-DR molecules were labelled with Alexa-546-conjugated IgG, as the acceptor. Results: We detected significant energy transfer between donor and acceptor-labelled antibodies against HLA-DR at the membrane surface of mDC. FRET data indicated that fluorescent peptide-loaded MHC II molecules start to accumulate on mDC membranes at 16 hr from the maturation stimulus, steeply increasing at 22 hr with sustained higher FRET detected up to 46 hr. Conclusions: The results obtained imply that the patient mDC correctly processed the tumor specific antigens and their display on the mDC surface may be effective for several days. These observations support the rationale for immunogenic efficacy of autologous tumor lysates

    The N2K Consortium. III. Short-Period Planets Orbiting HD 149143 and HD 109749

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    We report the detection of two short-period planets discovered at Keck Observatory. HD 149143 is a metal-rich G0 IV star with a planet of M sin i = 1.33M_J and an orbital radius of 0.053 AU. The best-fit Keplerian model has an orbital period, P = 4.072 days, semivelocity amplitude, K = 149.6 m s^(-1), and eccentricity, e = 0.016 ± 0.01. The host star is chromospherically inactive and metal-rich, with [Fe/H] = 0.26. Based on the T_(eff) and stellar luminosity, we derive a stellar radius of 1.49 R_☉. Photometric observations of HD 149143 were carried out using the automated photometric telescopes at Fairborn Observatory. HD 149143 is photometrically constant over the radial velocity period to 0.0003 ± 0.0002 mag, supporting the existence of the planetary companion. No transits were detected down to a photometric limit of approximately 0.02%, eliminating transiting planets with a variety of compositions and constraining the orbital inclination to less than 83°. A short-period planet was also detected around HD 109749, a G3 IV star. HD 109749 is chromospherically inactive, with [Fe/H] = 0.25 and a stellar radius of 1.24. The radial velocities for HD 109749 are modeled by a Keplerian with P = 5.24 days and K = 28.7 m s^(-1). The inferred planet mass is M sin i = 0.28M_J and the semimajor axis of this orbit is 0.0635 AU. Photometry of HD 109749 was obtained with the SMARTS consortium telescope, the PROMPT telescope, and by transitsearch.org observers in Adelaide and Pretoria. These observations did not detect a decrement in the brightness of the host star at the predicted ephemeris time, and they constrain the orbital inclination to less than 85° for gas giant planets with radii down to 0.7R_J
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