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Maximum Sensitivity (maximum + sensitivity)
Selected AbstractsHyperefficient PrPSc amplification of mouse-adapted BSE and scrapie strain by protein misfolding cyclic amplification techniqueFEBS JOURNAL, Issue 10 2009Aiko Fujihara Abnormal forms of prion protein (PrPSc) accumulate via structural conversion of normal PrP (PrPC) in the progression of transmissible spongiform encephalopathy. Under cell-free conditions, the process can be efficiently replicated using in vitro PrPSc amplification methods, including protein misfolding cyclic amplification. These methods enable ultrasensitive detection of PrPSc; however, there remain difficulties in utilizing them in practice. For example, to date, several rounds of protein misfolding cyclic amplification have been necessary to reach maximal sensitivity, which not only take several weeks, but also result in an increased risk of contamination. In this study, we sought to further promote the rate of PrPSc amplification in the protein misfolding cyclic amplification technique using mouse transmissible spongiform encephalopathy models infected with either mouse-adapted bovine spongiform encephalopathy or mouse-adapted scrapie, Chandler strain. Here, we demonstrate that appropriate regulation of sonication dramatically accelerates PrPSc amplification in both strains. In fact, we reached maximum sensitivity, allowing the ultrasensitive detection of < 1 LD50 of PrPSc in the diluted brain homogenates, after only one or two reaction rounds, and in addition, we detected PrPSc in the plasma of mouse-adapted bovine spongiform encephalopathy-infected mice. We believe that these results will advance the establishment of a fast, ultrasensitive diagnostic test for transmissible spongiform encephalopathies. [source] Measurement of low-dose active pharmaceutical ingredient in a pharmaceutical blend using frequency-domain photon migrationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2004Tianshu Pan Abstract Frequency-domain photon migration (FDPM) measurements of time-dependent light propagation are conducted to provide the powder absorbance for quantitative prediction of terazosin as the active pharmaceutical ingredient (API) in a low-dose (0.72 wt %) oral tablet formulation. Calibration of the FDPM-derived powder absorbance at discrete wavelengths of 514, 650, 687, and 785 nm was performed for API contents ranging between 0 and 1.5 wt % in mixtures showing maximum sensitivity at 650 nm. The relative standard deviation (RSD) of FDPM absorption coefficient measurement at 650 nm in a well-mixed 1.08 wt % terazosin blend was <1.6%, of which no more than 0.12% arose from FDPM instrumental error and the remainder was attributable to the complete-random-mixture model. The applicability of FDPM as an on-line sensor for powder-blending operations was further evaluated by analyzing grab samples taken directly from five locations of a 2-cu-ft Gallay blender at intervals of 5 min within the blending process. FDPM results indicate that homogeneity was largely achieved in the first 10 min, during which the RSD of API content across five sampling locations decreased from 27% to 8%, and the RSD decreased to 5% after 25 min of blending. Evolution of homogeneity within the blending process assessed through FDPM measurements was fit to the first-order model of particle blending further evidencing applicability for monitoring powder-blending processes. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:635,645, 2004 [source] Performance comparison of slow-light coupled-resonator optical gyroscopesLASER & PHOTONICS REVIEWS, Issue 5 2009M. Terrel Abstract We investigate the connection between group velocity and rotation sensitivity in a number of resonant gyroscope designs. Two key comparisons are made. First, we compare two conventional sensors, namely a resonant fiber optic gyroscope (RFOG) and an interferometric fiber optic gyroscope (FOG). Second, we compare the RFOG to several recently proposed coupled-resonator optical waveguide (CROW) gyroscopes. We show that the relationship between loss and maximum rotation sensitivity is the same for both conventional and CROW gyroscopes. Thus, coupling multiple resonators together cannot enhance rotation sensitivity. While CROW gyroscopes offer the potential for large group indices, this increase of group index does not provide a corresponding increase in the maximum sensitivity to rotation. For a given footprint and a given total loss, the highest sensitivity is shown to be achieved either in a conventional RFOG utilizing a single resonator, or a conventional FOG. [source] Determination of atenolol by the micelle-stabilized room-temperature phosphorescence methodologyLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 6 2007Marcela A. Castillo Abstract A micellar-stabilized room-temperature phosphorescence (MS,RTP) method for the determination of atenolol has been developed in micellar solutions of sodium dodecylsulphate (SDS) in the presence of thallium(I) as a heavy atom and sodium sulphite as an oxygen scavenger. The effects of thallium(I) nitrate, SDS and sodium sulphite concentrations on atenolol MS,RTP intensity were studied. Optimized conditions to obtain maximum sensitivity were 0.015 mol/L thallium(I) nitrate, 0.1 mol/L SDS and 0.0075 mol/L sodium sulphite. The maximum phosphorescence signal was completely developed in 10 min and the intensity was measured at ,ex = 272 nm and ,em = 412 nm. The linear range of application obtained was 2.01,16.00 µg/mL. The detection limit estimated from the least-squares regression analysis was 0.86 µg/mL and the relative standard deviation of 10 replicates was 1.7%. The proposed method was applied to the determination of atenolol in a pharmaceutical formulation. The quantitation was carried out by means of standard calibration, standard-additions calibration and Youden calibration. These three experiments were necessary to evaluate the presence of constant and proportional errors due to the matrix. Copyright © 2007 John Wiley & Sons, Ltd. [source] Revisiting The Ziegler-Nichols Tuning Rules For Pi ControlASIAN JOURNAL OF CONTROL, Issue 4 2002T. Hägglund ABSTRACT This paper presents new tuning rules for PI control of processes with essentially monotone step response that are typically encountered in process control. The rules are based on characterization of process dynamics by three parameters that can be obtained from a step response experiment. The rules are obtained by maximizing integral gain subject to a constraint on the maximum sensitivity. They are almost as simple as the Ziegler Nichols tuning rules but they give substantially better performance. [source] A Synthesis Method For Robust Pid Controllers For A Class Of Uncertain SystemsASIAN JOURNAL OF CONTROL, Issue 4 2002Stefan Solyom ABSTRACT PID controller design is considered where optimal controller parameters are found with constraint on maximum sensitivity and robustness with regard to a cone bounded static nonlinearity acting in feedback with part of the plant. The design procedure has been successfully applied in the synthesis of a controller for an Anti-lock Braking System (ABS). [source] Fluorescence correlation spectroscopy for the detection and study of single molecules in biologyBIOESSAYS, Issue 8 2002Miguel Ángel Medina The recent development of single molecule detection techniques has opened new horizons for the study of individual macromolecules under physiological conditions. Conformational subpopulations, internal dynamics and activity of single biomolecules, parameters that have so far been hidden in large ensemble averages, are now being unveiled. Herein, we review a particular attractive solution-based single molecule technique, fluorescence correlation spectroscopy (FCS). This time-averaging fluctuation analysis which is usually performed in Confocal setups combines maximum sensitivity with high statistical confidence. FCS has proven to be a very versatile and powerful tool for detection and temporal investigation of biomolecules at ultralow concentrations on surfaces, in solution, and in living cells. The introduction of dual-color cross-correlation and two-photon excitation in FCS experiments is currently increasing the number of promising applications of FCS to biological research. BioEssays 24:758,764, 2002. © 2002 Wiley Periodicals, Inc. [source] Liquid chromatography-tandem mass spectrometry method for determination of Sirolimus coated drug eluting nano porous carbon stentsBIOMEDICAL CHROMATOGRAPHY, Issue 3 2010G. Rajender Abstract Liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has proved to powerful research tool due to its sensitivity, high selectivity, and high throughput efficiency..Sirolimus was extracted from plasma by two-step extraction procedure using chloroform as extracting solvent. Signal intensity was high using ESI+ source provided for the quantitation of samples. Chromatographic separation was performed on phenomenax C-18 column (250 × 4.60,mm 5microns).Mobile phase contains acetonitrile, water (80; 20 v/v) + 0.1% acetic acid, flow rate 1,mL/min. The retention time of Sirolimus 8.4,min, the total run time10,min. Linearity correlation coefficients (r2) curve was 0.997183.calibraction range 10,1000,ng/mL. The UV detection of Sirolimus was at 278(277.78) nm. Sirolimus coated drug eluting stents, MRM (Multiple reaction monitoring) transition of Sirolimus m/z 936.83,208.84 was selected to obtain maximum sensitivity. LC/MS/MS results exhibited consistency in drug content on the stent surface. In-vitro release kinetic indicated the release of Sirolimus in 41 days from the date of implanted. Drug release was found at the first day, burst release was observed at 7th day of implantation. This study involved pharmacological coating of stents, based on the notion that sustained systemic local delivery of anti-proliferative agents. LC-MS/MS method has been successfully used in the pharmacokinetic analysis of Sirolimus coated drug eluting stents. Copyright © 2009 John Wiley & Sons, Ltd. [source] Validity of non-mydriatic cameras for screening and follow-up in diabetic retinopathyACTA OPHTHALMOLOGICA, Issue 2007J IBANEZ Purpose: To determine the validity of a non-mydriatic camera for screening and grading diabetic retinopathy (DR). To establish the number of photographs and the field width needed for a correct DR follow-up. Methods: A cross-sectional, observational study was carried out to assess the validity of the non-mydriatic Topcon TRC-NW6S retinograph. Validity proportions were calculated. Kappa analysis was made to determine the agreement with conventional fundoscopy exploration performed by indirect ophthalmoscopy and retinal biomicroscopy. One 45º single-field non-mydriatic digital photograph was taken in 82 eyes for DR screening. For DR grading, several combinations of retinal fields were photographed in 247 eyes, first without pupillary dilatation and later with mydriasis. Results: In DR screening, 88.2% sensitivity and 96.9% specificity were obtained, where 9% of the tests were invalid. In DR grading diagnosis, the kappa analysis showed close agreement (k>0.8) based on at least two 45º photographs with mydriasis. However, when attempting to detect macular edema (ME), the maximum kappa statistic obtained did not go above 0.71, showing 67% maximum sensitivity. The sensitivity for detecting derivable DR was similar to that obtained with indirect ophthalmoscopy (94-98%). Conclusions: The non-mydriatic retinograph is a valid instrument for DR screening only when taking one 45º non-mydriatic photograph per eye. However, given that the sensitivity for proliferative DR (PDR) was worse, when grading DR, we would recommend obtaining nine retinal photographs (mosaic) with mydriasis. Used in this way, the apparatus is extremely useful for detecting derivable DR cases. [source] | ||||||||||