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Limited Sensitivity (limited + sensitivity)
Selected AbstractsSimultaneous assessment of DNA ploidy and biomarker expression in paraffin-embedded tissue sectionsHISTOPATHOLOGY, Issue 1 2010Stijn J H M Fleskens Fleskens S J H M, Takes R P, Otte-Höller I, van Doesburg L, Smeets A, Speel E-J M, Slootweg P J & van der Laak J A W M (2010) Histopathology,57, 14,26 Simultaneous assessment of DNA ploidy and biomarker expression in paraffin-embedded tissue sections Aims:, Aneuploidy is a potential biomarker for predicting progression of premalignancies. Ploidy assessment is mostly performed on nuclei isolated from tissue sections. Ploidy assessment in situ in tissue sections may be a large improvement, enabling selective sampling of nuclei, thus allowing the correlation between ploidy and histology. Existing ploidy analysis methods in sections suffer from limited sensitivity. The aim was to reliably assess ploidy in sections, combined with simultaneous assessment of other markers at the individual cell level. Methods and results:, Ploidy was measured in 22 paraffin-embedded oral premalignancies. The DNA stoichiometric Feulgen procedure was used on isolated nuclei, as well as fluoresence in situ hybridization analysis. In tissue sections, Feulgen was combined with immunohistochemistry for Ki67 proliferation marker, enabling distinction between cycling euploid and aneuploid cells. Aneuploidy was reliably detected in tissue sections (sensitivity 100%, specificity 92%). One section in which aneuploidy was detected was misclassified in isolated nuclei analysis. Sections were also successfully analysed using our model combined with DNA double strand break marker ,-H2AX in fluorescence microscopy, underlining the power of biomarker evaluation on single cells in tissue sections. Conclusions:, The analysis model proposed in this study enables the combined analysis of histology, genotypic and phenotypic information. [source] Ophthalmic Artery Flow Direction on Color Flow Duplex Imaging Is Highly Specific for Severe Carotid StenosisJOURNAL OF NEUROIMAGING, Issue 1 2002Patrick S. Reynolds MD Background/Purpose. Collateral flow patterns are important risk factors for brain ischemia in the presence of internal carotid artery (ICA) stenosis or occlusion. Ophthalmic artery (OA) flow reversal, routinely studied by transcranial Doppler sonography, is an important marker for high-grade ICA stenosis or occlusion. The authors sought to define the value of assessing OA flow direction with color flow duplex ultrasonography (CDUS) in the setting of significant ICA disease. Methods. Of all patients having routine carotid ultrasound in the neurosonology laboratory between July 1995 and November 2000, 152 had both carotid and orbital (OA flow direction by reduced power orbital CDUS) examinations as well as angiographic confirmation of stenosis to which North American Symptomatic Carotid Endarterectomy Trial criteria could be applied. Degree of angiographic stenosis in these 152 patients (304 arteries) was correlated with OA flow direction. Results. Of 304 arteries, 101 had greater than 80% stenosis by angiogram. In 56 of these 101 arteries with high-grade stenosis or occlusion, the ipsilateral OA was reversed; however, OA flow direction was never reversed ipsilateral to arteries with less than 80% stenosis (sensitivity 55%, specificity 100%, negative predictive value 82%, and positive predictive value 100% for OA flow reversal as a marker of high-grade carotid lesions). Discussion/Conclusions. OA flow direction is easily studied with CDUS. Reversed OA flow direction is highly specific (100%) for severe ipsilateral ICA stenosis or occlusion, with excellent positive predictive value, moderate negative predictive value, and limited sensitivity. OA flow reversal is not only quite specific for severe ICA disease, which may be helpful if the carotid CDUS is difficult or inadequate, but may also provide additional hemodynamic insights (ie, the inadequacy of other collateral channels such as the anterior communicating artery). OA evaluation can provide important hemodynamic information and should be included as part of carotid CDUS if there is any evidence of ICA stenosis or occlusion. [source] Simultaneous detection of two verotoxin genes using dual-label time-resolved fluorescence immunoassay with duplex PCRLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 2 2002Kazuyuki Watanabe Abstract Verotoxin (VT) produced by several Escherichia coli serotypes causes haemorrhagic colitis and has been associated with haemolytic uraemic syndrome in humans. Two types of verotoxin are known. Conventional diagnosis of verotoxin-producing Escherichia coli (VTEC) is conducted after isolation of bacteria from clinical specimens, followed by serological determination and identification of VTs. This method is complicated and time-consuming. Recently, rapid, direct immunological methods for identification of VTEC, i.e. immunochromatography and latex agglutination, have been developed. However, these techniques continue to suffer from limited sensitivity and a lack of specificity. These difficulties arise from the fact that the antibody used in these procedures reacts exclusively with the O157 antigen; moreover, VTEC strains with non-O157 antigens, such as O26, O103 and O111 antigens, exist. These VTEC groups did not react with anti-O157 antibody. Consequently, it is necessary to diagnose the VT gene in these bacteria. Therefore, we have designed a sensitive and specific method for the detection of two VT genes simultaneously, utilizing duplex PCR with time-resolved fluorescence immunoassay (TRFIA). Copyright © 2002 John Wiley & Sons, Ltd. [source] Offline, multidetector intensity interferometers , I. TheoryMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2006Aviv Ofir ABSTRACT Stellar amplitude interferometry is limited by the need to have optical distances fixed and known to a fraction of the wavelength. We suggest reviving intensity interferometry, which requires hardware which is many orders of magnitude less accurate, at the cost of more limited sensitivity. We present an algorithm to use the very high redundancy of a uniform linear array to increase the sensitivity of the instrument by more than a 100-fold. When using an array of 100 elements, each almost 100 m in diameter, and conservative technological improvements, we can achieve a limiting magnitude of about mb= 14.4. Digitization, storage, and offline processing of all the data will also enable interferometric image reconstruction from a single observation run, and application of various algorithms at any later time. Coronagraphy, selectively suppressing only the large-scale structure of the source, can be achieved by specific aperture shapes. We conclude that after three decades of abandonment optical intensity interferometry deserves another review. [source] Radioimmunodiagnosis of lymph node metastases in head and neck cancerORAL DISEASES, Issue 5 2003R de Bree Introduction:, Reliable staging of the neck remains a diagnostic challenge in head and neck squamous cell carcinoma (HNSCC) patients. Monoclonal antibodies (MAbs) directed against tumour-associated antigens can be used for selective tumour targeting. When labelled with a , -emitting radionuclide like 99mTechnetium, such MAbs can be used for tumour detection by radioimmunoscintigraphy (RIS). Objective:, The aim of this study was to assess the potential of RIS for the detection of lymph node metastases in HNSCC patients. Patients and methods:, In 49 patients with HNSCC, who were scheduled to undergo surgery including neck dissection, RIS using 99mTc-labelled squamous cell specific MAb E48 or U36 administered intravenously was compared with clinical palpation, computed tomography (CT), magnetic resonance imaging (MRI) and histopathological outcome. Results:, RIS detected lymph node metastases in 35 of 51 positive sides (sensitivity 69%). Interpretation of RIS was correct in 47 of 65 sides (accuracy 72%). Accuracy of palpation, CT and MRI were comparable. Immunohistochemical staining of lymph node metastases missed by RIS showed that the injected MAb had targeted these small tumour deposits but these were not visualized. Conclusions:, RIS at its current stage of development is not superior to CT or MRI for the detection of lymph node metastases. As small tumour deposits were probably not visualized because of the limited sensitivity and/or spatial resolution of the gamma camera, positron emission tomography (PET) using MAbs labelled with positron emitters may improve the detection. As MAb-PET studies in an animal model showed promising results we will soon start a clinical MAb-PET study. [source] Urea-based two-dimensional electrophoresis of beta-amyloid peptides in human plasma: Evidence for novel A, speciesPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 20 2007Juan Manuel Maler Abstract The detailed analysis of ,-amyloid (A,) peptides in human plasma is still hampered by the limited sensitivity of available mass spectrometric methods and the lack of appropiate ELISAs to measure A, peptides other than A,1,38, A,1,40, and A,1,42. By combining high-yield A, immuno precipitation (IP), IEF, and urea-based A,-SDS-PAGE-immunoblot, at least 30 A,-immunoreactive spots were detected in human plasma samples as small as 1.6,mL. This approach clearly resolved A, peptides A,1,40, A,1-42, A,1-37, A,1-38, A,1-39, the N-truncated A,2,40, A,2,42, and, for the first time, also A,1,41. Relative quantification indicated that A,1,40 and A,1,42 accounted for less than 60% of the total amount of A, peptides in plasma. All other A, peptides appear to be either C-terminally or N-terminally truncated forms or as yet uncharacterized A, species which migrated as trains of spots with distinct pIs. The A, pattern found in cerebrospinal fluid (CSF) was substantially less complex. This sensitive method (2-D A,-WIB) might help clarifying the origin of distinct A, species from different tissues, cell types, or intracellular pools as well as their amyloidogenicity. It might further help identifying plasma A, species suitable as biomarkers for the diagnosis of Alzheimer's disease (AD). [source] Targeted lipidomics using electron capture atmospheric pressure chemical ionization mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 19 2003Seon Hwa Lee There is an increasing need to be able to conduct quantitative lipidomics analyses as a complement to proteomics studies. The highest specificity for proteomics analysis can be obtained using methodology based on electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) coupled with liquid chromatography/tandem mass spectrometry (LC/MS/MS). For lipidomics analysis it is often necessary to be able to separate enantiomers and regioisomers. This can be very challenging when using methodology based on conventional reversed-phase chromatography. Normal-phase chromatography using chiral columns can provide dramatic improvements in the resolution of enantiomers and regioisomers. However, conventional ESI- and APCI-MS/MS has limited sensitivity, which makes it difficult to conduct studies in cell culture systems where only trace amounts of non-esterified bioactive lipids are present. The use of electron capture APCI-MS/MS overcomes this problem. Enantiomers and regioisomers of diverse bioactive lipids can be quantified using stable isotope dilution methodology coupled with normal-phase chiral chromatography and electron capture APCI-MS/MS. This methodology has allowed a lipidomics profile from rat epithelial cells maintained in culture to be delineated and allowed the effect of a non-selective lipoxygenase inhibitor to be assessed. Copyright © 2003 John Wiley & Sons, Ltd. [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] | |||||||||||||