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Sensitivity Limit (sensitivity + limit)
Selected AbstractsUse of a multiplex PCR-based reverse line blot (mPCR/RLB) hybridisation assay for the rapid identification of bacterial pathogensCLINICAL MICROBIOLOGY AND INFECTION, Issue 2 2008Y. Wang Abstract The aim of this study was to develop a sensitive and reliable method for the molecular identification of pathogenic bacteria. A multiplex PCR-based reverse line blot (mPCR/RLB) hybridisation assay was developed and evaluated for the rapid identification of 24 systemic and respiratory bacterial pathogens in routine diagnosis. All species-specific probes designed for the RLB hybridised with amplified DNA only from the corresponding species. Sensitivity limits of the mPCR/RLB assay varied among the 24 target organisms from 0.05 pg to 0.5 ng of genomic DNA. The sensitivity of the assay was 2 × 102 CFU/mL for Streptococcus pneumoniae and 6 × 102 CFU/mL for Escherichia coli. The specificity of each probe was tested against 24 species. There were no cross-reactions among any of the 43 probes. The mPCR/RLB assay appeared to be a useful alternative tool for the molecular identification of common pathogens. [source] Individualized treatment strategy according to early viral kinetics in hepatitis C virus type 1,infected patients,,HEPATOLOGY, Issue 2 2009Thomas Berg Individualized treatment on the basis of early viral kinetics has been discussed to optimize antiviral therapy in chronic hepatitis C virus (HCV) infection. Individually tailored reduction in treatment duration in HCV type 1,infected patients represents one possible strategy. Four hundred thirty-three patients were randomly assigned to receive either 1.5 ,g/kg peginterferon alfa-2b weekly plus 800-1,400 mg ribavirin daily for 48 weeks (n = 225, group A) or an individually tailored treatment duration (18-48 weeks; n = 208, group B). In the latter group, treatment duration was calculated using the time required to induce HCV RNA negativity (branched DNA [bDNA] assay; sensitivity limit, 615 IU/mL) multiplied by the factor 6. All bDNA negative samples were retested with the more sensitive transcription-mediated amplification (TMA) assay (sensitivity limit, 5.3 IU/mL). Sustained virologic response (SVR) rates were significantly lower in group B (34.6% versus 48.0% [P = 0.005]) due to higher relapse rates (32.7% versus 14.2% [P< 0.0005]). Important predictors of response were the levels of baseline viremia as well as the time to TMA negativity on treatment. Taking the simultaneous presence of low baseline viral load (<800,000 IU/mL) and a negative TMA test within the first 4 weeks as predictors for treatment response, SVR rates were comparable between both treatment schedules with an SVR probability of >80% obtained in patients treated for only 18 or 24 weeks. Conclusion: The individualized treatment strategy according to time to bDNA negativity failed to provide comparable efficacy compared with the standard of care. The inferiority of the individualized protocol may be explained by the use of a less sensitive HCV RNA assay, and also by underestimation of the importance of baseline viremia. (HEPATOLOGY 2009.) [source] Lyman break galaxies and the star formation rate of the Universe at z, 6MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2003Elizabeth R. Stanway ABSTRACT We determine the space density of UV-luminous starburst galaxies at z, 6 using deep HST ACS SDSS- i, (F775W) and SDSS- z, (F850LP) and VLT ISAAC J and Ks band imaging of the Chandra Deep Field South. We find eight galaxies and one star with (i,,z,) > 1.5 to a depth of z,AB= 25.6 (an 8, detection in each of the 3 available ACS epochs). This corresponds to an unobscured star formation rate of ,15 h,270 M, yr,1 at z= 5.9, equivalent to L* for the Lyman-break population at z= 3,4 (,,= 0.7, ,M= 0.3). We are sensitive to star-forming galaxies at 5.6 ,z, 7.0 with an effective comoving volume of ,1.8 × 105h,370 Mpc3 after accounting for incompleteness at the higher redshifts due to luminosity bias. This volume should encompass the primeval subgalactic-scale fragments of the progenitors of about a thousand L* galaxies at the current epoch. We determine a volume-averaged global star formation rate of (6.7 ± 2.7) × 10,4h70 M, yr,1 Mpc,3 at z, 6 from rest-frame UV selected starbursts at the bright end of the luminosity function: this is a lower limit because of dust obscuration and galaxies below our sensitivity limit. This measurement shows that at z, 6 the star formation density at the bright end is a factor of ,6 times less than that determined by Steidel et al. for a comparable sample of UV-selected galaxies at z= 3,4, and so extends our knowledge of the star formation history of the Universe to earlier times than previous work and into the epoch where reionization may have occurred. [source] A Study of Gypsum Scale Formation using Quartz Crystal MicrobalanceASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1-2 2006T. A. Hoang The quartz crystal microbalance (QCM) has been used extensively as a mass sensor due to its extremely high sensitivity to small mass loadings. Conventional measurement of the amount of scale deposited on a surface is restricted by the sensitivity limit of analytical balances. Thefirst attempt to investigate the deposition of gypsum scale on a surface using a rotating electrochemical QCMsystem was carried out to investigate the eflects of many factors at the early stages of scale formation. Results indicated there was almost no induction time for this system, and the long induction time observed in the conventional system was due to the limited sensitivity of the analytical balance. A slow increase in scale amount was observed at the beginning of the scaling process as shown by the plot offrequency or mass change against time. After this period the curve rises steeply and becomes almost linear. The supersaturation level of the solutions and the rotating speed have significant effects on the gypsum scaling. A QCM flow-cell system has also been developed to investigate the scaling of gypsum on the pipe wall. This system is similar to a conventional pipe flow system except that its size is much smaller and the deposition of scales can be monitored with the QCM electrode throughout the scaling process. The mass change is plotted against time and results are compared for the rotating QCM system and the conventional system. It is noticed that the formation of gypsum on the QCM electrode is greatly dependent on both the supersaturation of the solution and the flow rate of the fluid passing through the flow cell. [source] Can molecular mechanisms of biological processes be extracted from expression profiles?BIOESSAYS, Issue 12 2001Case study: endothelial contribution to tumor-induced angiogenesis Whereas the genome contains all potential developmental programs, expression profiles permit the determination of genes that are actively transcribed under defined physiological conditions. In this article, the idea of extracting biological mechanisms from expression data is tested. Molecular processes of the endothelial contribution to angiogenesis are derived from recently published expression profiles. The analysis reveals the sensitivity limits of experimental detection of transcriptional changes and how sequence-analytic techniques can help to identify the function of genes in question. We conclude that the transcripts (http://mendel.imp.univie.ac.at/SEQUENCES/TEMS/) found to be up-regulated in angiogenesis are involved in extracellular matrix remodeling, cellular migration, adhesion, cell-cell communication rather than in angiogenesis initiation or integrative control. Comparison with tissue-specific patterns of EST occurrence shows that, indeed, the presumptive tumor-specific endothelial markers are more generally expressed by cell types involved in migration and matrix remodeling processes. This exemplary study demonstrates how bioinformatics approaches can be helpful in deriving mechanistic information from diverse sources of experimental data. BioEssays 23:1159,1175, 2001. © 2001 John Wiley & Sons, Inc. [source] | ||||||||||