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False Positives (false + positive)
Terms modified by False Positives Selected AbstractsCoronary pressure never liesCATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 2 2008Jacques J. Koolen MD Abstract Fractional Flow Reserve (FFR), calculated by coronary pressure measurement, is the invasive gold standard to assess the hemodynamic significance of a coronary stenosis. FFR reliably indicates whether a stenosis is responsible for inducible ischemia and if percutaneous coronary intervention is appropriate. False positive or negative FFR is rare. Occasionally, however, a clinical or angiographic condition is encountered in which in first instance the FFR measurement contradicts the intuitive feeling of the interventionalist. Further examination in such cases, however, often reveals a clear physiologic explanation and in this manner FFR "lifts the veil". Two such patients are presented in this case report and the reasons for apparent or actual false positive or negative FFR are discussed. © 2008 Wiley-Liss, Inc. [source] Meta-analyses of the effect of false-positive mammograms on generic and specific psychosocial outcomesPSYCHO-ONCOLOGY, Issue 10 2010Talya Salz Abstract Objectives: While a previous meta-analysis found that false-positive mammography results affect women's likelihood of returning for screening, effects on well being have yet to be meta-analyzed. We investigated whether the effects of false-positive mammograms on women's well-being are limited to outcomes specific to breast cancer. Methods: We searched MEDLINE for studies of the psychosocial effects of false-positive results of routine screening mammography. We pooled effect sizes using random effects meta-analysis. Results: Across 17 studies (n=20,781), receiving a false-positive mammogram the result was associated with differences in all eight breast-cancer-specific outcomes that we examined. These included greater anxiety and distress about breast cancer as well as more frequent breast self-exams and higher perceived effectiveness of screening mammography. False positives were associated with only one of six generic outcomes (i.e. generalized anxiety), and this effect size was small. Conclusions: False-positive mammograms influenced women's well-being, but the effects were limited to breast-cancer-specific outcomes. Researchers should include disease-specific measures in future studies of the consequences of false-positive mammograms. Copyright © 2010 John Wiley & Sons, Ltd. [source] Feasibility of different mass spectrometric techniques and programs for automated metabolite profiling of tramadol in human urineRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 14 2006Kati S. Hakala The purpose of the study was to determine the advantages of different mass spectrometric instruments and commercially available metabolite identification programs for metabolite profiling. Metabolism of tramadol hydrochloride and the excretion of it and its metabolites into human urine were used as a test case because the metabolism of tramadol is extensive and well known. Accurate mass measurements were carried out with a quadrupole time-of-flight mass spectrometer (Q-TOF) equipped with a LockSpray dual-electrospray ionization source. A triple quadrupole mass spectrometer (QqQ) was applied for full scan, product ion scan, precursor ion scan and neutral loss scan measurements and an ion trap instrument for full scan and product ion measurements. The performance of two metabolite identification programs was tested. The results showed that metabolite programs are time-saving tools but not yet capable of fully automated metabolite profiling. Detection of non-expected metabolites, especially at low concentrations in a complex matrix, is still almost impossible. With low-resolution instruments urine samples proved to be challenging even in a search for expected metabolites. Many false-positive hits were obtained with the automated searching and manual evaluation of the resulting data was required. False positives were avoided by using the higher mass accuracy Q-TOF. Automated programs were useful for constructing product ion methods, but the time-consuming interpretation of mass spectra was done manually. High-quality MS/MS spectra acquired on the QqQ instrument were used for confirmation of the tramadol metabolites. Although the ion trap instrument is of undisputable benefit in MSn, the low mass cutoff of the ion trap made the identification of tramadol metabolites difficult. Some previously unreported metabolites of tramadol were found in the tramadol urine sample, and their identification was based solely on LC/MS and LC/MS/MS measurements. Copyright © 2006 John Wiley & Sons, Ltd. [source] The Essence of Linkage-based Imprinting Detection: Comparing Power, Type 1 Error, and the Effects of Confounders in Two Different Analysis ApproachesANNALS OF HUMAN GENETICS, Issue 3 2010David A. Greenberg Summary Imprinting is critical to understanding disease expression. It can be detected using linkage information, but the effects of potential confounders (heterogeneity, sex-specific penetrance, and sex-biased ascertainment) have not been explored. We examine power and confounders in two imprinting detection approaches, and we explore imprinting-linkage interaction. One method (PP) models imprinting by maximising lod scores w.r.t. parent-specific penetrances. The second (DRF) approximates imprinting by maximising lods over differential male-female recombination fractions. We compared power, type 1 error, and confounder effects in these two methods, using computer-simulated data. We varied heterogeneity, penetrance, family and dataset size, and confounders that might mimic imprinting. Without heterogeneity, PP had more imprinting-detecting power than DRF. PP's power increased when parental affectedness status was ignored, but decreased with heterogeneity. With heterogeneity, type 1 error increased dramatically for both methods. However, DRF's power also increased under heterogeneity, more than was attributable to inflated type 1 error. Sex-specific penetrance could increase false positives for PP but not for DRF. False positives did not increase on ascertainment through an affected "mother". For PP, non-penetrant individuals increased information, arguing against using affecteds-only methods. The high type 1 error levels under some circumstances means these methods must be used cautiously. [source] Skin-sensitizing and irritant properties of propylene glycolCONTACT DERMATITIS, Issue 5 2005Data analysis of a multicentre surveillance network (IVDK, review of the literature In the several publications reviewed in this article, propylene glycol (PG; 1,2-propylene glycol) is described as a very weak contact sensitizer, if at all. However, particular exposures to PG-containing products might be associated with an elevated risk of sensitization. To identify such exposures, we analysed patch test data of 45 138 patients who have been tested with 20% PG in water between 1992 and 2002. Out of these, 1044 patients (2.3%) tested positively, 1083 showed a doubtful, follicular or erythematous reaction (2.4%) and 271 explicit irritant reactions (0.6%). This profile of patch test reactions is indicative of a slightly irritant preparation, and thus, many of the ,weak positive' reactions must probably be interpreted as false positive. No private or occupational exposures associated with an increased risk of PG sensitization were identified, except for lower leg dermatitis. Therefore, according to our patch test data, PG seems to exhibit very low sensitization potential, and the risk for sensitization to PG on uncompromised skin seems to be very low. [source] FS02.8 Patch testing with gold trichloride can give false test resultsCONTACT DERMATITIS, Issue 3 2004Birgitta Gruvberger Background:, Hydrochloric acid is formed in water solutions of gold trichloride. Hydrochloric acid in contact with aluminium generates hydrogen gas which can reduce and transform trivalent gold to elemental gold. Objective:, To investigate whether patch testing with aqueous gold trichloride can cause false positive (irritant) reactions in patients without contact allergy to gold and false negative reactions in patients with gold allergy. Methods:, 13 patients with and 13 patients without positive patch test reactions to gold sodium thiosulfate were tested with gold trichloride in 2 different vehicles, water and alkaline buffer, using 2 different test techniques, the Finn Chamber technique with aluminium chambers and van der Bend technique with polypropene chambers. Results:, Irritant patch test reactions were obtained with aqueous gold trichloride tested in van der Bend chambers in 10 patients without gold allergy. In gold-allergic patients no positive test reactions were obtained from aqueous gold trichloride in Finn chambers while 2 positive test reactions were obtained from gold trichloride in alkaline buffer tested in van der Bend chambers. Conclusion:, If gold trichloride is patch tested in wrong vehicle and with wrong test technique irritant test reactions may occur which can be misinterpreted as positive allergic reactions in patients without gold allergy as well as negative reactions in patients with gold allergy. [source] FC02.4 Meteorological factors and standard series patch test reactionsCONTACT DERMATITIS, Issue 3 2004Janice Hegewald The existence of seasonal patterns to patch test reactions has been described, but with conflicting causal interpretations. The potential seasonality of patch tests may be due to irritation, changes to skin barrier or changes to immunological functions caused by meteorological fluctuations. For example, increased skin irritability due to cold winter weather and low humidity may cause an increase in irritative/doubtful and weak positive (false positive) reactions. To investigate the extent of the association between weather and patch test results, consecutive patients (N = 73691) patch tested with the standard series of the German Contact Dermatitis Research Group (DKG) at German or Austrian IVDK (http://www.ivdk.de) centres were matched with weather data collected at a nearby (30 km radius) weather station. Temperature and absolute humidity (AH) on the day of patch test application and the two preceding days were averaged to represent the environment most likely to have influenced the skin condition at the time of testing. The results of 24 standard series substances were analyzed with multivariate logistic regression. Half of the standard series substances examined, including fragrance mix, nickel sulphate, and formaldehyde, exhibited evidence of a relationship with meteorological conditions. Fragrance mix and p-Phenylene diamine exhibited the strongest evidence of an association to weather, with the odds of the reactions in all three reaction categories (ir/?, +, ++/+++) increasing during winter conditions. Due to the association between weather and patch test reactivity, the potential effect of meteorological conditions should be considered in the interpretation of patch test reactions. [source] Comparative study: conventional cervical and ThinPrep® Pap tests in a routine clinical settingCYTOPATHOLOGY, Issue 4 2002A. Grace The conventional Papanicolaou smear is associated with variable false positive and false negative rates, difficulties with interpretation and high unsatisfactory and suboptimal rates. Newer fluid-based methods such as the ThinPrep® 2000 system (Cytyc Corp., Boxborough, MA) are said to overcome these difficulties. The aim of this study was to compare the conventional smear with the ThinPrep® method in a busy, routine cytology screening laboratory setting. One thousand split samples were evaluated. Using ThinPrep®, the results showed an increased sensitivity and a dramatic improvement in specimen adequacy, with a combined 17.2% reduction in ,unsatisfactory' and ,suboptimal' reports. Screening time per slide was also reduced to 3,4 min. In conclusion, we report an increase in sensitivity, a reduction in screening time and a dramatic improvement in specimen adequacy with the ThinPrep® method. [source] Impact of Valvular Calcification on the Diagnostic Accuracy of Transesophageal Echocardiography for the Detection of Congenital Aortic Valve MalformationECHOCARDIOGRAPHY, Issue 7 2007Akash Makkar M.D. Background: Degeneration of congenital bicuspid or unicuspid aortic valves can progress more rapidly than that of tricuspid valves, and an early diagnosis significantly impacts decision making and outcome. We hypothesized that the extent of valvular calcification would negatively influence the diagnostic accuracy of multiplane transesophageal echocardiography (TEE) for the diagnosis of congenital aortic valve disease. Methods: TEE was performed in 57 patients undergoing aortic valve replacement surgery for aortic stenosis (n = 46), pure regurgitation (n = 9), or significant regurgitation with less than severe aortic stenosis (n = 2). The degree of aortic valve calcification and the number of valve cusps were determined at surgery. Results: Surgical inspection confirmed 14 bicuspid and 43 tricuspid aortic valves. Sensitivity and specificity of TEE for the diagnosis of congenital aortic valve malformation was 93% (13/14) and 91% (39/43) (P = 0.0001), respectively. In patients with no or mild aortic valve calcification (n = 13), sensitivity and specificity of TEE for the diagnosis of congenitally malformed aortic valve was 100% (5/5) and 100% (8/8) (P = 0.001), respectively. In patients with moderate or marked aortic valve calcification (n = 44), sensitivity and specificity of TEE for the diagnosis of congenitally malformed aortic valve was 89% (8/9) and 89% (31/35) (P<0.0001), respectively. In this subgroup of 44 patients, there were four false-positive and one false-negative diagnoses due to valvular calcification. Conclusions: Although TEE is highly sensitive and specific for the detection of congenital aortic valve malformations, presence of moderate or marked calcification of the aortic valve may result in false positive and false negative diagnoses. [source] Protocol for Optimal Detection and Exclusion of a Patent Foramen Ovale Using Transthoracic Echocardiography with Agitated Saline MicrobubblesECHOCARDIOGRAPHY, Issue 7 2006Robert R. Attaran M.B.Ch.B. Agitated saline bubble studies in conjunction with echocardiography, in particular transesophageal echocardiography, are currently the principal means in the diagnosis of patent foramen ovale (PFO). We describe techniques and guidelines for the detection and exclusion of a PFO. The potential for misinterpretation of these bubble studies exists and therefore, several false positive and false negative scenarios are illustrated and discussed. [source] Evaluation of PG-M3 antibody in the diagnosis of acute promyelocytic leukaemiaEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 10 2010Sanjeev Kumar Gupta Eur J Clin Invest 2010; 40 (10): 960,962 Abstract Background & objectives, Acute promyelocytic leukaemia (APL) is a distinct subtype of acute myeloid leukaemia (AML) characterized by a reciprocal translocation, t(15;17) and a high incidence of life-threatening coagulopathy. APL diagnosis is considered a medical emergency. As reverse transcription-polymerase chain reaction (RT-PCR) for PML-RAR, fusion oncoprotein is time consuming, there is a need for a rapid and accurate diagnostic test for APL. This study evaluates the role of PG-M3 monoclonal antibody using immunofluorescence (IF) in the early diagnosis of APL. Materials and Methods, Thirty-six new untreated APL cases diagnosed with RT-PCR for PML-RAR, as the gold standard and 38 non-APL controls (28 non-APL AMLs and 10 non-leukaemic samples) were evaluated by routine morphology and cytochemistry, RT-PCR and IF using PG-M3 monoclonal antibody. Results, Using IF, 34 of 36 (94·4%) APL cases showed a microgranular pattern suggestive of APL and two cases (5·6%) showed a speckled pattern typical of wild-type PML protein (False negative). By comparison, two of 28 (7·1%) non-APL AMLs showed microgranular pattern (false positive). Hence, IF as a diagnostic test for APL resulted in a sensitivity of 94·4%, specificity of 92·9% and positive and negative predictive values of 94·4% and 92·9% respectively. All 10 non-leukaemic samples showed a speckled pattern. Conclusions, IF using PG-M3 antibodies can be used as a rapid (takes 2 h), cheap, sensitive and specific method to identify APL. It can be a useful adjunct for diagnosis of APL especially if facilities for RT-PCR are not available, particularly in resource-limited settings. [source] Examining the statistical properties of fine-scale mapping in large-scale association studiesGENETIC EPIDEMIOLOGY, Issue 3 2008Steven Wiltshire Abstract Interpretation of dense single nucleotide polymorphism (SNP) follow-up of genome-wide association or linkage scan signals can be facilitated by establishing expectation for the behaviour of primary mapping signals upon fine-mapping, under both null and alternative hypotheses. We examined the inferences that can be made regarding the posterior probability of a real genetic effect and considered different disease-mapping strategies and prior probabilities of association. We investigated the impact of the extent of linkage disequilibrium between the disease SNP and the primary analysis signal and the extent to which the disease gene can be physically localised under these scenarios. We found that large increases in significance (>2 orders of magnitude) appear in the exclusive domain of genuine genetic effects, especially in the follow-up of genome-wide association scans or consensus regions from multiple linkage scans. Fine-mapping significant association signals that reside directly under linkage peaks yield little improvement in an already high posterior probability of a real effect. Following fine-mapping, those signals that increase in significance also demonstrate improved localisation. We found local linkage disequiliptium patterns around the primary analysis signal(s) and tagging efficacy of typed markers to play an important role in determining a suitable interval for fine-mapping. Our findings help inform the interpretation and design of dense SNP-mapping follow-up studies, thus facilitating discrimination between a genuine genetic effect and chance fluctuation (false positive). Genet. Epidemiol. 2007. © 2007 Wiley-Liss, Inc. [source] Place and value of the recurrent laryngeal nerve (RLN) palpatory method in preventing RLN palsy during thyroid surgeryHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 4 2009DSci, Áron Altorjay MD Abstract Background. In recent years, certain publications have appeared confirming that intraoperative palpation of the recurrent laryngeal nerve (RLN) is a very reliable method. Method. The characteristics of the surgical anatomy of 1023 RLN have been summarized on the basis of intraoperative palpability, running down, branching variations, thickness, and laryngeal entry site. Results. Palpation was helpful in 81.4% (833/1023), proved false positive in 8.2% (84/1023), and in 10.4% (106/1023) it was of no help in the exact localization. Definitive RLN palsy was experienced in 0.78% of all cases (8/1023), while transient paresis was encountered in 1.2% (12/1023). Only a moderately strong stochastic correlation could be found between RLN palsies and those nerves which were nonpalpable and atypical, which showed the joint occurrence of being both thinner than normal and branching already before the plane of the inferior thyroid artery (Cramer's associate coefficient, C = 0.383). Conclusion. Palpation alone cannot substitute visualization and proper surgical dissection of the nerve. © 2008 Wiley Periodicals, Inc. Head Neck, 2009 [source] Screening for the BRCA1-ins6kbEx13 mutation: potential for misdiagnosis,,HUMAN MUTATION, Issue 5 2007Susan J Ramus Abstract Misdiagnosis of a germline mutation associated with an inherited disease syndrome can have serious implications for the clinical management of patients. A false negative diagnosis (mutation missed by genetic screening) limits decision making about intervention strategies within families. More serious is the consequence of a false positive diagnosis (genetic test suggesting a mutation is present when it is not). This could lead to an individual, falsely diagnosed as a mutation carrier, undergoing unnecessary clinical intervention, possibly involving risk-reducing surgery. As part of screening 283 ovarian cancer families for BRCA1 mutations, we used two different methods (mutation specific PCR and multiplex ligation-dependant probe amplification) to screen for a known rearrangement mutation L78833.1:g.44369_50449dup (ins6kbEx13). We found false positive and false negative results in several families. We then tested 61 known carriers or non-carriers from an epidemiological study of BRCA1 and BRCA2 mutation carriers (the EMBRACE study). These data highlight the need for caution when interpreting analyses of the ins6kbEx13 mutation and similar mutations, where characterising the exact sequence alteration for a deleterious mutation is not a part of the routine genetic test. © 2007 Wiley-Liss, Inc. [source] Extracting bird migration information from C-band Doppler weather radarsIBIS, Issue 4 2008HANS VAN GASTEREN Although radar has been used in studies of bird migration for 60 years, there is still no network in Europe for comprehensive monitoring of bird migration. Europe has a dense network of military air surveillance radars but most systems are not directly suitable for reliable bird monitoring. Since the early 1990s, Doppler radars and wind profilers have been introduced in meteorology to measure wind. These wind measurements are known to be contaminated with insect and bird echoes. The aim of the present research is to assess how bird migration information can be deduced from meteorological Doppler radar output. We compare the observations on migrating birds using a dedicated X-band bird radar with those using a C-band Doppler weather radar. The observations were collected in the Netherlands, from 1 March to 22 May 2003. In this period, the bird radar showed that densities of more than one bird per km3 are present in 20% of all measurements. Among these measurements, the weather radar correctly recognized 86% of the cases when birds were present; in 38% of the cases with no birds detected by the bird radar, the weather radar claimed bird presence (false positive). The comparison showed that in this study reliable altitudinal density profiles of birds cannot be obtained from the weather radar. However, when integrated over altitude, weather radar reflectivity is correlated with bird radar density. Moreover, bird flight speeds from both radars show good agreement in 78% of cases, and flight direction in 73% of cases. The usefulness of the existing network of weather radars for deducing information on bird migration offers a great opportunity for a European-wide monitoring network of bird migration. [source] Review of pulp sensibility tests.INTERNATIONAL ENDODONTIC JOURNAL, Issue 9 2010Part I: general information, thermal tests Jafarzadeh H, Abbott PV. Review of pulp sensibility tests. Part ,: general information and thermal tests. International Endodontic Journal, 43, 738,762, 2010. Abstract A major, and essential, part of the diagnostic process for pulp disease is the use of pulp sensibility tests. When diagnosing pulp pain, these tests can be used to reproduce the symptoms reported by the patient to diagnose the diseased tooth as well as the disease state. However, a major shortcoming with these tests is that they only indirectly provide an indication of the state of the pulp by measuring a neural response rather than the vascular supply, so both false positive and false negative results can occur. The relevant literature on pulp sensibility tests in the context of endodontics up to January 2009 was reviewed using PubMed and MEDLINE database searches. This search identified papers published between November 1964 and January 2009 in all languages. Thermal tests have been used as an integral part of dental examinations. Two types of thermal tests are available, one uses a cold stimulus and the other uses a hot stimulus, and each has various methods of delivery. If these tests are used properly, injury to the pulp is highly unlikely. A review of the literature regarding the rationale, indications, limitations, and interpretation of thermal tests, the value of these diagnostic tests, as well as a discussion of the important points about each of these tests is presented. [source] Skin sensitization, false positives and false negatives: experience with guinea pig assaysJOURNAL OF APPLIED TOXICOLOGY, Issue 5 2010David A. Basketter Abstract The advent of the local lymph node assay (LLNA), and efforts to develop in vitro alternatives for the identification of skin sensitizing chemicals has focused attention on the issue of false positive and false negative results. In essence, the question becomes ,what is the gold standard?' In this context, attention has focused primarily on the LLNA as this is now the preferred assay for skin sensitization testing. However, for many years prior to introduction of the LLNA, the guinea pig maximization test and the occluded patch test of Buehler were the methods of choice. In order to encourage a more informed dialogue about the relative performance, accuracy and applicability of the LLNA and guinea pig tests, we have here considered the extent to which guinea pig methods were themselves subject to false positives and negative results. We describe and discuss here well-characterized examples of instances where both false negatives (including abietic acid and eugenol) or false positives (including vanillin and sulfanilic acid) have been recorded in guinea pig tests. These and other examples are discussed with particular reference to the fabrication of a gold standard dataset that is required for the validation of in vitro alternatives. Copyright © 2010 John Wiley & Sons, Ltd. [source] Nonreplication in Genetic Studies of Complex Diseases,Lessons Learned From Studies of Osteoporosis and Tentative Remedies,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 3 2005Hui Shen Abstract Inconsistent results have accumulated in genetic studies of complex diseases/traits over the past decade. Using osteoporosis as an example, we address major potential factors for the nonreplication results and propose some potential remedies. Over the past decade, numerous linkage and association studies have been performed to search for genes predisposing to complex human diseases. However, relatively little success has been achieved, and inconsistent results have accumulated. We argue that those nonreplication results are not unexpected, given the complicated nature of complex diseases and a number of confounding factors. In this article, based on our experience in genetic studies of osteoporosis, we discuss major potential factors for the inconsistent results and propose some potential remedies. We believe that one of the main reasons for this lack of reproducibility is overinterpretation of nominally significant results from studies with insufficient statistical power. We indicate that the power of a study is not only influenced by the sample size, but also by genetic heterogeneity, the extent and degree of linkage disequilibrium (LD) between the markers tested and the causal variants, and the allele frequency differences between them. We also discuss the effects of other confounding factors, including population stratification, phenotype difference, genotype and phenotype quality control, multiple testing, and genuine biological differences. In addition, we note that with low statistical power, even a "replicated" finding is still likely to be a false positive. We believe that with rigorous control of study design and interpretation of different outcomes, inconsistency will be largely reduced, and the chances of successfully revealing genetic components of complex diseases will be greatly improved. [source] Low specificity of anti-tissue transglutaminase antibodies in patients with primary biliary cirrhosisJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 5 2006N. Bizzaro Abstract The association between celiac disease (CD) and primary biliary cirrhosis (PBC) is well documented in medical literature; however, a high frequency of false positive results of the anti-transglutaminase (anti-tTG) test has been reported in patients with PBC. To verify if the positive results for anti-tTG autoantibody are false positives due to cross reactivity with mitochondrial antigens, we studied 105 adult patients affected with PBC, positive for anti-mitochondrial M2 antibodies. Anti-tTG IgA antibodies were studied by using six different immunoenzymatic assays that employ the tTG antigen obtained from different sources (human recombinant, placenta, red blood cells, and guinea pig liver). On the whole, 28 out of 105 PBC subjects tested positive for anti-tTG IgA antibodies, but only two were eventually found to be affected by CD; the other 26 were shown to be false positive. The specificity of the various antigenic substrates ranged from 88.5% of the human erythrocytes tTG to 97.1% of the human recombinant tTG. The results of this study showed that a true association between PBC and CD was present in only 2% of the patients and that, in most cases, the false positive results were attributable to the type of substrate utilized in the assay. J. Clin. Lab. Anal. 20:184,189, 2006. © 2006 Wiley-Liss, Inc. [source] Fine-needle aspiration cytology to distinguish dysplasia from hepatocellular carcinoma with different gradesJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 7pt2 2008Chen-Chun Lin Abstract Background:, Distinguishing dysplasia from hepatocellular carcinoma (HCC) by fine-needle aspiration (FNA) cytology is difficult. The aim of this study was to diagnose HCC and the distinction of liver cell dysplasia from HCC with different grades by interpreting and scoring the cyto-morphological features. Methods:, Eighty-three cirrhotic patients undertook a sonography-guided FNA and subsequent needle biopsy for the tumor. HCC was confirmed in 68 cases and cirrhosis with dysplasia in 15 cases by pathology and follow-up for longer than 2 years. Eighteen cytological features were scored as degree of one, two or three according to their presence or prominence. Results:, Two cases of well-differentiated HCC were diagnosed as negative for HCC initially. The sensitivity, specificity, false positive, false negative and accuracy were 97%, 100%, 0%, 3% and 97.6% for FNA cytology in the diagnosis of HCC, respectively. The score of dysplasia was 20.8 ± 1.3 (mean ± SD) and lower than 26.2 ± 3.4 in Edmondson's grade I HCC (P < 0.01), 28.9 ± 2.9 in grade II HCC (P < 0.01), and 34.9 ± 4.3 in grade III/IV HCC (P < 0.01). The score was also significantly lower in grade II HCC than in grade III/IV HCC (P < 0.01). Conclusions:, FNA yielded a high accuracy in the distinction of dysplasia from HCC with different grades. There is a good correlation in cyto-morphological scores of liver cell dysplasia and HCC with different grades. Dysplasia displayed the lowest score and the score increased in order from dysplasia to grade III/IV HCC. [source] Appropriate cut-off value of 13C-urea breath test after eradication of Helicobacter pylori infection in JapanJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 12 2003CHIEKO KATO Abstract Background and Aim:, A cut-off value of 2.5, for the 13C-urea breath test (UBT) is recommended in Japanese persons, based on the result of a multicenter trial in patients prior to treatment for eradication of Helicobacter pylori. The cut-off value of 2.5, has also been used in the assessment of eradication after treatment. The 6,8-week evaluation after treatment is recommended in the guidelines of the Japanese Society of Gastroenterology. The present study aimed to prospectively re-assess the cut-off value of the 13C-UBT at 6 weeks after treatment by using the results obtained at 6 months as an indication of true positive or true negative H. pylori infection status. Methods:, One hundred and ninety patients who were positive for H. pylori underwent eradication treatment, and 177 patients of these patients who were assessed as having true positive or true negative H. pylori,status ,at ,6 months ,after ,treatment ,were ,evaluated ,in ,this ,study. ,Eradication ,was ,assessed ,by 13C-UBT, ,culture, ,and ,histology ,at ,6 weeks ,and ,at ,6 months ,after ,treatment, ,and ,the ,cut-off ,value ,of 13C-UBT at 6 weeks was re-assessed. Results:, A cut-off value of 3.5,. at 6 weeks after treatment showed 97.2% diagnostic accuracy, while a cut-off value of 2.5, at 6 weeks showed 96.0% diagnostic accuracy. For a 3.5, cut-off value, only five patients were positive by 13C-UBT and were negative by culture and histology at 6 weeks, and three patients were true positive and two were false positive by the 13C-UBT at 6 months. Conclusion:, A cut-off value of 3.5, for the 13C-UBT is recommended at 6 weeks after eradication treatment in Japanese persons. [source] Systematic determination of ion score cutoffs based on calculated false positive rates: application for identifying ubiquitinated proteins by tandem mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 3 2008Julian Vasilescu Abstract We report a simple approach for determining ion score cutoffs that permit the confident identification of ubiquitinated proteins by tandem mass spectrometry (MS/MS). Initial experiments involving the analysis of gel bands containing multi-Ubiquitin chains with quadrupole time-of-flight and quadrupole ion trap mass spectrometers revealed that standard ion score cutoffs used for database searching were not sufficiently stringent. We also found that false positive and false negative rates (FPR and FNR) varied significantly depending on the cutoff scores used and that appropriate cutoffs could only be determined following a systematic evaluation of false positive rates. When standard cutoff scores were used for the analysis of complex mixtures of ubiquitinated proteins, unacceptably high FPR were observed. Finally, we found that FPR for ubiquitinated proteins are affected by the size of the protein database that is searched. These observations may be applicable for the study of other post-translational modifications. Copyright © 2007 John Wiley & Sons, Ltd. [source] Impact of 18F-fluorodeoxyglucose positron emission tomography in the staging and treatment response assessment of extra-pulmonary small-cell cancerJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 2 2010DL Gregory Summary The aim of this study was to retrospectively evaluate the value of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in extrapulmonary small-cell cancer (EPSCC). Patients with EPSCC who underwent PET for staging or response assessment between 1996 and 2007 were identified from a database. Patient records were reviewed. PET-based, and conventional staging and restaging results were compared. The binary staging classification of limited disease (LD) versus extensive disease (ED) was used. Patients with LD had tumours that could be encompassed within a tolerable radiation therapy (RT) volume. Of 33 eligible patients, 12 had staging PET scans, 11 had restaging scans and 10 had both. All known gross disease sites were FDG-avid. PET and conventional stage groupings were concordant in 21 of 22 cases. One patient was appropriately upstaged from LD to ED by PET. PET detected additional disease sites, without causing upstaging in three further patients. Restaging PET scans identified previously unrecognised persistent or progressive disease in 4 of 21 cases. In four further cases, persistent FDG uptake after treatment was either false positive (n = 2) or of uncertain (n = 2) aetiology. PPV was 100% for staging and 82% for restaging. In 8 of 43 imaging episodes (19%), PET appropriately influenced management in five cases by changing treatment intent from radical to palliative, and in three cases by altering the RT volume. PET has incremental value compared to conventional imaging for staging EPSCC, and may also be useful for restaging after therapy. PET influenced patient management in 19% of 43 imaging episodes. [source] Delineating protein,protein interactions via biomolecular interaction analysis,mass spectrometryJOURNAL OF MOLECULAR RECOGNITION, Issue 1 2003Dobrin Nedelkov Abstract The utility of biomolecular interaction analysis,mass spectrometry (BIA/MS) in screening for protein,protein interactions was explored in this work. Experiments were performed in which proteins served as ligands for screening of possible interactions with other proteins from human plasma and urine. The proteins utilized were beta-2-microglobulin, cystatin C (cysC), retinol binding protein (RBP), transthyretin (TTR), alpha-1-microglobulin, C-reactive protein, transferrin and papain. The immobilization of functionally active proteins was confirmed via interactions with antibodies to the corresponding proteins. Various dilutions of human urine and plasma were injected over the protein-derivatized surfaces. It was observed that the urine injections generally yielded smaller SPR responses than those observed after the plasma injections. The BIA/MS experiments did not reveal novel protein,protein interactions, although several established interactions (such as those between RBP and TTR, and cysC and papain) were validated. Few protein ligand deficiencies (such as truncations) leading to false negative and false positive BIA/MS results were also discovered. Copyright © 2003 John Wiley & Sons, Ltd. [source] Detection of Right-to-Left Shunts: Comparison between the International Consensus and Spencer Logarithmic Scale CriteriaJOURNAL OF NEUROIMAGING, Issue 4 2008Annabelle Y. Lao ABSTRACT BACKGROUND International Consensus Criteria (ICC) consider right-to-left shunt (RLS) present when Transcranial Doppler (TCD) detects even one microbubble (,B). Spencer Logarithmic Scale (SLS) offers more grades of RLS with detection of >30 ,B corresponding to a large shunt. We compared the yield of ICC and SLS in detection and quantification of a large RLS. SUBJECTS AND METHODS We prospectively evaluated paradoxical embolism in consecutive patients with ischemic strokes or transient ischemic attack (TIA) using injections of 9 cc saline agitated with 1 cc of air. Results were classified according to ICC [negative (no ,B), grade I (1-20 ,B), grade II (>20 ,B or "shower" appearance of ,B), and grade III ("curtain" appearance of ,B)] and SLS criteria [negative (no ,B), grade I (1-10 ,B), grade II (11-30 ,B), grade III (31100 ,B), grade IV (101300 ,B), grade V (>300 ,B)]. The RLS size was defined as large (>4 mm) using diameter measurement of the septal defects on transesophageal echocardiography (TEE). RESULTS TCD comparison to TEE showed 24 true positive, 48 true negative, 4 false positive, and 2 false negative cases (sensitivity 92.3%, specificity 92.3%, positive predictive value (PPV) 85.7%, negative predictive value (NPV) 96%, and accuracy 92.3%) for any RLS presence. Both ICC and SLS were 100% sensitive for detection of large RLS. ICC and SLS criteria yielded a false positive rate of 24.4% and 7.7%, respectively when compared to TEE. CONCLUSIONS Although both grading scales provide agreement as to any shunt presence, using the Spencer Scale grade III or higher can decrease by one-half the number of false positive TCD diagnoses to predict large RLS on TEE. [source] Analysis of the breath hydrogen test for carbohydrate malabsorption: Validation of a pocket-sized breath test analyserJOURNAL OF PAEDIATRICS AND CHILD HEALTH, Issue 4 2000Ws Lee Objective: To assess the validity and clinical application of a hand-held breath hydrogen (H2) analyzer (BreatH2, Europa Scientific, Crewe, UK). Methodology: Breath samples of patients referred to the Gastroenterology Unit, Women's and Children's Hospital, North Adelaide, South Australia, for confirmation of the diagnosis of carbohydrate malabsorption were analysed with the Quintron microlyzer (Quintron Instrument Co., Milwaukee, USA) and the BreatH2 analyser, using the Quintron microlyzer as the gold standard. Results: Twenty-nine breath H2 tests (BHT) were performed in 29 patients aged 2 months to 61 years. The sensitivity and specificity of the BreatH2 analyser in detecting a positive BHT using the Quintron microlyser as the gold standard were 0.90 and 0.95 with positive and negative predictive values of 0.90 and 0.95, respectively. There was one false positive and one false negative reading. Bland,Altman plots showed a high degree of agreement between the values obtained with two different methods. Conclusions: The diagnosis of carbohydrate malabsorption, using a portable breath H2 analyser (BreatH2), achieved an acceptable degree of sensitivity and specificity, enabling it to be used where no alternative is available. [source] Evaluation of the Ez-HBT Helicobacter blood test to establish Helicobacter pylori eradicationALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 9 2005F. AHMED Summary Background :,The urea blood test (Ez-HBT) has been shown to compare favourably with the urea breath test in the diagnosis of active Helicobacter pylori infection. Aim :,To examine the performance characteristics of the Ez-HBT Helicobacter blood test in establishing success or failure of therapy in H. pylori -infected adults using the 13C urea breath test as the reference method. Methods :,13C urea breath test and Ez-HBT Helicobacter blood test were performed 4,6 weeks after completion of treatment in H. pylori positive subjects. Basal urea breath samples were collected; basal Ez-HBT Helicobacter blood test samples were not. Ez-HBT Helicobacter blood test results were reported as positive, negative, or indeterminate. Results :,Seventy patients generated 126 measurable sets of urea breath and blood tests. The H. pylori cure rate was 93%. The sensitivity, specificity, and accuracy of the Ez-HBT Helicobacter blood test were 100%, 97%, and 97%, respectively. Six of eight false positive and indeterminate Ez-HBT Helicobacter blood test results could be attributed to incomplete fasting or a 13C enriched diet. After correcting for the non-fasting state, the positive predictive value of the Ez-HBT Helicobacter blood test improved from 56% to 86%. Conclusion :,The performance characteristics of the Ez-HBT Helicobacter blood test are comparable with that of 13C-urea breath test in establishing H. pylori eradication after therapy. Errors related to incomplete fasting can be mitigated by collection of a basal blood sample. [source] When is an oral food challenge positive?ALLERGY, Issue 1 2010B. Niggemann Abstract Oral food challenges still remain the gold standard in the diagnosis of food related symptoms and are performed to obtain a clear ,yes or no' response. However, this is often difficult to achieve, and so proposals may be appropriate for criteria on when to stop oral food challenges. In daily practice it makes sense to challenge until clear objective symptoms occur without harming the patient. Clinical symptoms should be objective and/or: (a) severe or (b) reproducible or (c) persisting. A sensitive parameter for a beginning clinical reaction is a general change of mood. The sooner symptoms appear, the more likely they are to represent a ,true' positive reaction and the more organ systems are involved the easier it is to assess an oral food challenge as positive. In the case of subjective symptoms, the number of placebo doses should be increased. In unclear situations, the observation time until the next dose should be prolonged or the same dose repeated. Transient objective clinical symptoms usually end up in a positive challenge result. There are a number of causes for false positive and false negative challenge results, which should be considered. The aim of all oral challenge testing should be to hold the balance between two conflicting aspects: on the one hand the need to achieve clear and justified results from oral food challenges in order to avoid unnecessary diets, and on the other hand to protect patients from any harm caused by high doses of a potentially dangerous food. [source] Comparison of conventional FASTA identity searches with the 80 amino acid sliding window FASTA search for the elucidation of potential identities to known allergensMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 8 2007Gregory S. Ladics Abstract Food and Agriculture Organization/World Health Organization (FAO/WHO) recommended that IgE cross-reactivity between a transgenic protein and allergen be considered when there is ,F 35% identity over a sliding "window" of 80 amino acids. Our objective was to evaluate the false positive and negative rates observed using the FAO/WHO versus conventional FASTA analyses. Data used as queries against allergen databases and analyzed to assess false positive rates included: 1102 hypothetical corn ORFs; 907 randomly selected proteins; 89 randomly selected corn proteins; and 97 corn seed proteins. To evaluate false negative rates of both methods: Bet v 1a along with several crossreacting fruit/vegetable allergens and a bean ,-amylase inhibitor were used as queries. Both methods were also evaluated for their ability to detect a putative nonallergenic test protein containing a sequence derived from Ara h 1. FASTA versions 3.3t0 and 3.4t25 were utilized. Data indicate a conventional FASTA analysis produced fewer false positives and equivalent false negative rates. Conventional FASTA versus sliding window derived E scores were generally more significant. Results suggest a conventional FASTA search provides more relevant identity to the query protein and better reflects the functional similarities between proteins. It is recommended that the conventional FASTA analysis be conducted to compare identities of proteins to allergens. [source] Nuchal translucency measurement at different crown-rump lengths along the 10- to 14-week period for Down syndrome screeningPRENATAL DIAGNOSIS, Issue 5 2005Maria A. Zoppi Abstract Objectives To evaluate the screening accuracy for Down syndrome of nuchal translucency (NT) measurement at different crown-rump length (CRL) subgroups along the 10- to 14-week period. Methods NT was classified ,enlarged' if greater than or equal to 1.5 and 2.0 multiples of the regressed median. Accuracies for Down syndrome (formula = [(TP + TN)/(TP + TN + FP + FN)] × 100, where TP: true positive, TN: true negative, FP: false positive, FN: false negative) were evaluated in four classes of CRL: 38,44 mm, 45,54 mm, 55,70 mm, and 71,84 mm, and compared. Results Of 20 743 fetuses, 20 611 were with no chromosomal abnormalities and 132 were with Down syndrome. Down syndrome fetuses with enlarged NT were 99 (greater than or equal to 1.5 MoM) and 86 (greater than or equal to 2.0 MoM). Sensitivity decreased with gestation, while specificity increased, resulting in increasing likelihood ratios with gestation for each of the CRL groups (8.1, 14.1, 16.3, 17.1 with the use of the 1.5 MoM cut-off, and 13.2, 27.1, 50.1, 84.1 for the 2.0 MoM cut-off). The accuracy increased with gestation (89%, 95%, 95%, 96% with the use of the 1.5 MoM cut-off, and 94%, 97%, 98%, 99% for the 2.0 MoM cut-off, for each of the CRL groups), differences being statistically significant between periods in half of the comparisons. Conclusions Although sensitivity of NT assessment for Down syndrome screening decreased as gestation advanced from the 10th to the 14th week, accuracy showed a remarkable increase. These changes should be taken into account in defining and improving the Down syndrome screening policies. Copyright © 2005 John Wiley & Sons, Ltd. 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