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False Negatives (false + negative)
Terms modified by False Negatives Selected AbstractsAn Experimental Investigation of the Effects of Acknowledging False Negative and False Positive Errors on Clients' Cancer Screening Intentions: The Lesser of Two Evils?APPLIED PSYCHOLOGY: HEALTH AND WELL-BEING, Issue 2 2010Shoshana Shiloh Two studies investigated people's motivations for testing, and the influence of awareness of test inaccuracies, on their intentions to undergo cancer screening tests. Study 1 used a between-subjects design in which participants stated their intentions regarding one of several screening tests with equal accuracy but with either false negative, false positive, or unspecified errors. Study 2 used a within-subjects design in which participants indicated their intentions regarding each of those screening tests. In Study 1, intentions for testing were relatively high, affected by instrumental (illness prevention) motivations, and unaffected by type of error acknowledged. Individuals with higher emotional (reassurance seeking) motivations had lower intentions to uptake tests with false positive errors. In Study 2, intentions to uptake all tests were lower compared to Study 1, and were affected by emotional motivations. Participants preferred a test with unspecified errors over tests with specified errors, and, when forced to choose, preferred tests with false negative over false positive errors. Findings are discussed in relation to Error Management Theory and Self-Regulation Theory, emphasising the need to recognise motivations, affect, and framing as important factors in informed screening decisions. [source] O-10 Endometrial cells in cervical smears: cytological features associated with clinically significant endometrial pathologyCYTOPATHOLOGY, Issue 2007R. N. Tiam Introduction:, To establish the significance of cytological features which could predict clinically significant endometrial pathology, and therefore guide reporting practice in cervical samples. Methods:, A retrospective review of SurePath liquid-based cytology (LBC) cervical samples between 2002 and 2006, obtained at screening and colposcopy. These smears contained normal endometrial cells present at inappropriate times of the menstrual cycle, endometrial cells with atypia (borderline change) and with features suspicious / diagnostic of endometrial carcinoma (glandular neoplasia). False negative and false positive cases detected on subsequent histology were also included. The control group comprised negative samples and a few abnormal smears. All smears were randomly assigned and blinded to menopausal status, age, use of oral contraceptive pill and hormone replacement therapy and presence of intrauterine device. Each smear was reviewed for 16 cytologic criteria and a cytological diagnosis was given for each. Results:, A total of 219 smears were available for review; 137 were negative, out of which 85 contained normal endometrial cells, 41 contained endometrial cells with atypia, 10 contained endometrial cells with features suggestive of adenocarcinoma and 31 contained endometrial cells with features diagnostic of adenocarcinoma. The feature most associated with benign endometrial cells is top hat with central cell condensation. In contrast, the features associated with malignant endometrial cells are smooth nuclear membrane, pale chromatin, small nucleoli and scalloped borders. Discussion:, The criteria identified in this study do not definitively define a neoplastic process, but appear to be helpful in individual cases. This study emphasises that endometrial changes should be always interpreted with the relevant clinical information, which would otherwise lead to overdiagnosis in premenopausal women. [source] Sentinel Lymph Node Biopsy in Cutaneous Squamous Cell Carcinoma: A Systematic Review of the English LiteratureDERMATOLOGIC SURGERY, Issue 11 2006AMY SIMON ROSS MD BACKGROUND Although most cutaneous squamous cell carcinoma (SCC) is curable by a variety of treatment modalities, a small subset of tumors recur, metastasize, and result in death. Although risk factors for metastasis have been described, there are little data available on appropriate workup and staging of patients with high-risk SCC. OBJECTIVE We reviewed reported cases and case series of SCC in which sentinel lymph node biopsy (SLNB) was performed to determine whether further research is warranted in developing SLNB as a staging tool for patients with high-risk SCC. METHODS The English medical literature was reviewed for reports of SLNB in patients with cutaneous SCC. Data from anogenital and nonanogenital cases were collected and analyzed separately. The percentage of cases with a positive sentinel lymph node (SLN) was calculated. False negative and nondetection rates were tabulated. Rates of local recurrence, nodal and distant metastasis, and disease-specific death were reported. RESULTS A total of 607 patients with anogenital SCC and 85 patients with nonanogenital SCC were included in the analysis. A SLN could not be identified in 3% of anogenital and 4% of nonanogenital cases. SLNB was positive in 24% of anogenital and 21% of nonanogenital patients. False-negative rates as determined by completion lymphadenectomy were 4% (8/213) and 5% (1/20), respectively. Most false-negative results were reported in studies from 2000 or earlier in which the combination of radioisotope and blue dye was not used in the SLN localization process. Complications were reported rarely and were limited to hematoma, seroma, cutaneous lymphatic fistula, wound infection, and dehiscence. CONCLUSIONS Owing to the lack of controlled studies, it is premature to draw conclusions regarding the utility of SLNB in SCC. The available data, however, suggest that SLNB accurately diagnoses subclinical lymph node metastasis with few false-negative results and low morbidity. Controlled studies are needed to demonstrate whether early detection of subclinical nodal metastasis will lead to improved disease-free or overall survival for patients with high-risk SCC. [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] Review article: Helicobacter pylori -negative duodenal ulcer diseaseALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 8 2009J. P. GISBERT Aliment Pharmacol Ther,30, 791,815 Summary Background,Helicobacter pylori infection rates in duodenal ulcer (DU) patients may be lower than previously estimated. Aim, To review the real prevalence of H. pylori -negative DUs and its possible causes. Methods, Bibliographical searches in MEDLINE looking for the terms ,H. pylori' and ,duodenal ulcer'. Results, Mean prevalence of H. pylori infection in DU disease, calculated from studies published during the last 10 years including a total of 16 080 patients, was 81%, and this figure was lower (77%) when only the last 5 years were considered. Associations with H. pylori -negative DU were: (1) False negative results of diagnostic methods, (2) NSAID use (21% in studies with <90% infection rate), (3) Complicated DU (bleeding, obstruction, perforation), (4) Smoking, (5) Isolated H. pylori duodenal colonization, (6) Older age, (7) Gastric hypersecretion, (8) Diseases of the duodenal mucosa, (9) Helicobacter,heilmanii' infection and (10) Concomitant diseases. Conclusion, In patients with H. pylori -negative DU disease, one should carefully confirm that the assessment of H. pylori status is reliable. In truly H. pylori -negative patients, the most common single cause of DU is, by far, the use of NSAIDs. Ulcers not associated with H. pylori, NSAIDs or other obvious causes should, for the present, be viewed as ,idiopathic'. True idiopathic DU disease only exceptionally exists. [source] Field and Laboratory Alcohol Detection With 2 Types of Transdermal DevicesALCOHOLISM, Issue 4 2009Paul R. Marques Background:, Two types of transdermal electrochemical sensors that detect alcohol at the skin surface were evaluated. One, the AMS SCRAMÔ device, is locked onto the ankle and is based on a fuel cell sensor; the other, a Giner WrisTASÔ device, worn on the wrist, is based on a proton exchange membrane. SCRAM is used by several court systems in the United States to monitor alcohol offenders, WrisTAS, a research prototype, is not commercially available. Methods:, The 2 devices were worn concurrently by 22 paid research subjects (15 men, 7 women), for a combined total of 96 weeks. Subjects participated in both laboratory-dosed drinking to a target of 0.08 g/dl blood alcohol concentration (BAC), and normal drinking on their own; all subjects were trained to use and carry a portable fuel-cell breath tester for BAC determinations. Overall 271 drinking episodes with BAC , 0.02 g/dl formed the signal for detection,60 from laboratory dosing, and 211 from self-dosed drinking, with BAC ranging from 0.02 to 0.230 g/dl (mean 0.077 g/dl). Results:, False negatives were defined as a transdermal alcohol concentration response equivalent <0.02 g/dl when BAC , 0.02 g/dl. The overall true-positive hit rate detected by WrisTAS was 24%. The low detection rate was due to erratic output and not recording during nearly 67% of all episodes; reportedly a chipset, not a sensor problem. SCRAM correctly detected 57% across all BAC events, with another 22% (total 79%) detected, but as <0.02 g/dl. When subjects dosed themselves to BAC , 0.08 g/dl, SCRAM correctly detected 88% of these events. SCRAM devices lost accuracy over time likely due to water accumulation in the sensor housing. Neither unit had false-positive problems when true BAC was <0.02 g/dl. Conclusions:, Each device had peculiarities that reduced performance, but both types are able to detect alcohol at the skin surface. With product improvements, transdermal sensing may become a valuable way to monitor the alcohol consumption of those who should be abstaining. [source] A Review of Genetic, Biological, Pharmacological, and Clinical Factors That Affect Carbohydrate-Deficient Transferrin LevelsALCOHOLISM, Issue 9 2004Michael F. Fleming Background: Carbohydrate-deficient transferrin (CDT) is an alcohol biomarker recently approved by the U.S. Food and Drug Administration. This test is increasingly being used to detect and monitor alcohol use in a variety of health care, legal, and industrial settings. The goal of this study is to review the genetic, biological, pharmacological, and clinical factors that may affect CDT levels. Methods: A review of the literature identified 95 research articles that met the authors' criteria and reported potential interactions of a variety of factors on percent and total CDT levels. The review established 12 categories of variables that may affect CDT levels. These categories include (1) alcohol use, (2) genetic factors, (3) race, (4) gender, (5) age, (6) liver disease, (7) iron levels, (8) tobacco use, (9) medication such as estrogen and anticonvulsants, (10) metabolic factors such as body mass index and total body water, (11) chronic medical conditions such as rheumatoid arthritis, and (12) surgical patients. Results: There is evidence that %CDT levels are affected by alcohol use, end-stage liver disease, and genetic variants. In addition to these three factors, total CDT levels (CDTect) are also affected by factors that raise transferrin levels such as iron deficiency, chronic illnesses, and menopausal status. Other potential factors such as tobacco and age appear to be confounded by alcohol use. The roles of female gender, low body mass index, chronic inflammatory diseases, and medication on CDT levels require further study. False negatives are associated with female gender, episodic lower level alcohol use, and acute trauma with blood loss. Conclusions: This review suggests that a number of factors are associated with false-positive CDTect and %CDT levels. CDT offers great promise to assist physicians in the care of patients to detect and monitor heavy alcohol use. [source] A host species-informative internal control for molecular assessment of African swine fever virus infection rates in the African sylvatic cycle Ornithodoros vectorMEDICAL AND VETERINARY ENTOMOLOGY, Issue 4 2009A. D. S. BASTOS Abstract African swine fever virus (ASFV) infection in adult Ornithodoros porcinus (Murry 1877, sensuWalton 1979) ticks collected from warthog burrows in southern and East Africa was assessed using a duplex genomic amplification approach that is informative with respect to the invertebrate host species and infecting sylvatic cycle virus. DNA extracted from individual ticks was used as template for the simultaneous amplification of a C-terminal 478-bp ASFV p72 gene region and a ,313-bp fragment of the tick mitochondrial 16S rRNA gene, under optimized reaction conditions. Within-warthog burrow infection rates ranged from 0% to 43% using this approach, and phylogenetic analysis of 16S gene sequences revealed the presence of three geographically discrete O. porcinus lineages, but no support for subspecies recognition. False negatives are precluded by the inclusion of host species-informative primers that ensure the DNA integrity of cytoplasmically located genome extracts. In addition, infection rate estimates are further improved as false positives arising from carry-over contamination when performing a two-step nested polymerase chain reaction are negated by the one-step approach. Phylogenetic comparison of full-length virus gene sequences with the partial C-terminal p72 gene target confirmed the epidemiological utility of the latter in a sylvatic setting. The method is therefore of particular value in studies assessing the prevalence and diversity of ASFV in relation to the African sylvatic tick vector and holds potential for investigating the role of alternative tick species in virus maintenance and transmission. [source] Efficacy of laser Doppler flowmetry for the diagnosis of revascularization of reimplanted immature dog teethDENTAL TRAUMATOLOGY, Issue 2 2001Kallaya Yanpiset Abstract , This study was performed to assess if laser Doppler flowmetry (LDF) is an improved method for the detection of revascularization of replanted teeth. Teeth were extracted and reimplanted under different experimental conditions. LDF readings were taken before extraction and weekly for 3 months. In control teeth, LDF baseline readings were taken and then repeated after the apical blood vessels were cut surgically. At the end of 3 months it was determined radiographically and histologically whether revascularization had occurred, i.e. vitality had returned. Results: LDF readings correctly predicted the pulp status (vital vs. non-vital) in 83.7% of the readings. 73.9% (17 of 23) were correct for the vital teeth and 95% (19 of 20) were correct for the non-vital teeth. Fisher's exact test (2-tail) indicated that there was no significant association between the efficacy of LDF and tooth type (P=0.166), although P2 was the least accurate tooth tested. Wilcoxon's matched-pair signed rank test demonstrated that in the revascularized (vital) teeth, the flux value between the baseline and week 2 dropped significantly (P=0.0001), increased significantly from week 2 to week 4 (P=0.0001) and then decreased steadily until week 12. However, at week 12 the flux was still significantly higher than at week 2 (P=0.010). In the teeth that failed to revascularize, the flux value dropped significantly by weeks 1 and 2 (P=0.004 and P=0.0001, respectively). Flux values did not increase from week 2. A Fast Fourier Transform (FFT) analysis confirmed a pulse of dominant frequency of 2 Hz in the teeth that returned to vitality and the lack thereof in those that stayed non-vital. One tooth in which the flux value evaluation indicated a non-vital tooth but the radiographic/histologic findings showed vital (false negative) possessed a pulse of dominant frequency and proved by this method to have successfully revascularized. [source] Fine-needle aspiration cytology of salivary glands: Diagnostic pitfalls,revisitedDIAGNOSTIC CYTOPATHOLOGY, Issue 8 2006Arvind Rajwanshi M.D., F.R.C.Path. Abstract Fine needle aspiration cytology (FNAC) of salivary gland lesions is a safe, effective diagnostic technique. Several amply illustrated reviews are available in the English literature. The reported diagnostic accuracy varies between 86% to 98%. The sensitivity ranges from 62% to 97.6% and specificity is higher from 94.3% to 100%. In this present study, we have analyzed 172 cases of salivary gland aspirates and the histopathological diagnosis was available in 45 cases. There was discordance in cytological and histopathological diagnosis in nine cases. Five cases had discrepancies in benign versus malignant diagnosis with four cases being false negative. The errors in these FNA diagnoses were due to sampling error, observational error and interpretational error. Therefore, this study illustrates high diagnostic accuracy of FNAC in salivary gland lesions and shows that FNAC offers valuable information that allows the planning of subsequent patient management. Diagn. Cytopathol. 2006;34:580,584. © 2006 Wiley-Liss, Inc. [source] Rapid review of liquid-based smears as a quality control measureDIAGNOSTIC CYTOPATHOLOGY, Issue 3 2004Sheryl Henderson M.Med.Sc.(Cytol.) Abstract The objective of this study was to investigate the effectiveness of a standardized method of rapid review (RR) of monolayer preparations for the identification of abnormalities, the presence of an endocervical component and infectious agents. A total of 200 ThinPrep (Cytyc, Boxborough, MA) slides representing the spectrum of abnormalities commonly encountered in cervical/vaginal cytologic specimens was retrieved from archive. The study set comprised 129 cases within normal limits (WNL); 36 low-grade epithelial abnormalities (LGEA); 28 high-grade epithelial abnormalities (HGEA), including 2 endocervical adenocarcinomas in situ (AIS) and 7 carcinomas. Eighteen false negative (FN) cases were also included for study. Originally missed on initial review, these cases were found to be abnormal on quality control review (17 LGEA; 1 AIS). Commonly encountered infectious agents were represented and included Candida albicans, Trichomonas vaginalis, herpes simplex virus, and Actinomyces. The slides were reviewed using a standardized method of RR (turret technique, for 60 sec) by three experienced screeners masked to the original reference diagnosis. Median sensitivity for LGEA was 70% (range, 67,72%); HGEA, 69% (range, 54,80%); and FN, 65% (range, 56,78%). Specificity remained high, median specificity for LGEA was 95%; HGEA, 97%; and FN, 100%. There was no significant overcalling of any diagnostic category. The chi-square test at P < 0.05 showed no significant difference between RR and full manual rescreen of the ThinPrep smears in this study. While no statistical difference was proven, the sensitivity measurements for all categories of abnormality were moderate due to the high proportion of atypical cases included into the study set. Abnormalities on the monolayer preparations frequently displayed fewer, smaller groups of disaggregated cells with rounded cytoplasmic outlines that were difficult to discern on RR. Interobserver variation was noted. Monolayers with a paucity of diagnostic cells and those displaying subtle nuclear atypia were often overlooked. Diagn. Cytopathol. 2004;31:141,146. © 2004 Wiley-Liss, Inc. [source] Sentinel node biopsy in oral cavity cancer: Correlation with PET scan and immunohistochemistryHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 1 2003Francisco J. Civantos MD Abstract Background. Lymphoscintigraphy and sentinel node biopsy (LS/SNB) is a minimally invasive technique that samples first-echelon lymph nodes to predict the need for more extensive neck dissection. Methods. We evaluated this technique in 18 oral cavity cancers, stages T1,T3, N0. Patients underwent CT and positron emission tomography (PET) of the neck, followed by LS/SNB, frozen section, immediate selective neck dissection, definitive histology, and immunoperoxidase staining for cytokeratin. Histopathology of the sentinel node was correlated with that of the neck specimen. Results. There were 10 true positives: 6 identified on frozen section; 2 on permanent histology; and 2 only on immunoperoxidase staining. In six, the sentinel node was the only positive node. There were seven true negatives and one false negative. Conclusions. Gross tumor replacement of lymph node architecture may obstruct and redirect lymphatic flow. Overall LS/SNB holds promise for oral cancer. © 2002 Wiley Periodicals, Inc. Head Neck 25: 000,000, 2003 [source] A comparison of diagnostic efficacies among different reagent strips and automated cell count in spontaneous bacterial peritonitisJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 5 2010Rungsun Rerknimitr Abstract Background:, Currently, decision to give antibiotics in spontaneous bacterial peritonitis (SBP) suspected patient depends mainly on the result of manual cell count, which requires significant waiting period. Recently, many reports on the efficacies of reagent strips and a few reports of automated cell count are available but there has been no direct comparison study. Aims:, This prospective study was to assess the diagnostic efficacies of different reagent strips (Aution, Multistix, Combur) and automated cell count. Methods and Results:, A total of 250 paracenteses were performed. There were 40 specimens obtained from patients with clinical suspicion for SBP, the rest were obtained from non SBP suspected patients. Thirty specimens from 250 samples (12%) were diagnosed as SBP by manual cell count. Automated system provided higher value for SBP diagnosis in all parameters (sensitivity, specificity, PPV, NPV, and accuracy; 87.5,99.1%) whereas the strip tests provided lower number in all parameters (80,98.6%). Multistix provided the lowest sensitivity (80%). The false negative rates by Aution, Multistix, Combur tests and automated cell count were 10%, 20%, 10% and 3.3%, respectively. By lowering the cut off for SBP diagnosis with the automated system to 200 cells/mm3, there was no false negative. Conclusions:, Comparing to reagent strips, automated cell count is a better screening tool for SBP diagnosis because it provides higher validity scores and a lower false negative rate. However, the discrepancy of cell count reading may occur, we suggest using a lower cut off for SBP diagnosis by the automated system. [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] 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] Simultaneous PCR Detection of the Two Major Bacterial Pathogens of GeraniumJOURNAL OF PHYTOPATHOLOGY, Issue 2 2002D. L. GLICK Xanthomonas campestris pv. pelargonii (Xcp) and Ralstonia solanacearum (Rs) are the two most important bacterial pathogens of commercially cultivated geraniums (Pelargonium spp.), both causing bacterial wilt and leaf spot. Asymptomatic infections are important reservoirs of infections in commercial growing facilities. Our objective was to design a multiplex PCR (Polymerase Chain Reaction) assay to detect infection by either or both of these pathogens. We used a previously characterized PCR primer pair for Xcp that amplifies a region of 200 bp. In addition, we designed a new primer pair specific for Rs that amplifies a region of 822 bp. With these two primer pairs, we could detect either or both pathogens. As geranium tissue extracts frequently contain inhibitors of the PCR process, a negative PCR could result from either an accurate indication that the plant was pathogen-free or from a false negative assay. We therefore designed `amplification competence' primers, targeting a portion of the geranium 18 s rRNA gene, and generating a 494-bp amplification product that confirms amplification competence and validates a negative assay result. Thus, the triple primer pair multiplex PCR screens for the two most important bacterial pathogens of geraniums simultaneously confirms amplification competence for each geranium sample. [source] Forecasting murder within a population of probationers and parolees: a high stakes application of statistical learningJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES A (STATISTICS IN SOCIETY), Issue 1 2009Richard Berk Summary., Forecasts of future dangerousness are often used to inform the sentencing decisions of convicted offenders. For individuals who are sentenced to probation or paroled to community supervision, such forecasts affect the conditions under which they are to be supervised. The statistical criterion for these forecasts is commonly called recidivism, which is defined as a charge or conviction for any new offence, no matter how minor. Only rarely do such forecasts make distinctions on the basis of the seriousness of offences. Yet seriousness may be central to public concerns, and judges are increasingly required by law and sentencing guidelines to make assessments of seriousness. At the very least, information about seriousness is essential for allocating scarce resources for community supervision of convicted offenders. The paper focuses only on murderous conduct by individuals on probation or parole. Using data on a population of over 60000 cases from Philadelphia's Adult Probation and Parole Department, we forecast whether each offender will be charged with a homicide or attempted homicide within 2 years of beginning community supervision. We use a statistical learning approach that makes no assumptions about how predictors are related to the outcome. We also build in the costs of false negative and false positive charges and use half of the data to build the forecasting model, and the other half of the data to evaluate the quality of the forecasts. Forecasts that are based on this approach offer the possibility of concentrating rehabilitation, treatment and surveillance resources on a small subset of convicted offenders who may be in greatest need, and who pose the greatest risk to society. [source] Accuracy of a new ultrafast rapid urease test to diagnose Helicobacter pylori infection in 1000 consecutive dyspeptic patientsALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2010D. VAIRA Summary Background, Rapid diagnostic tools for Helicobacter pylori are important in endoscopy. Aims, To assess the accuracy of a new 5 min rapid urease test (UFT300, ABS Srl, Cernusco sul Naviglio, Milan, Italy) and to compare it with the 1 h Pyloritek (Serim Laboratories, Elkhart, IN, USA) and the 24 h CLO test (Kimberly-Clark Ballard Medical Products, Roswell, GA, USA). Method, Consecutive dyspeptic patients referred to our unit for endoscopy were prospectively studied. All patients underwent a 13C-urea-breath test, histology and the UFT300 (ABS Srl; Cernusco sul Naviglio, Milan, Italy). In a sub-set of patients (n = 375), two additional RUTs were performed. Patients were deemed infected if both 13C-UBT and histology were positive. RUTs were read at 1, 5, and 60 min. Results, Of 1000 enrolled patients 45.3% were infected with H. pylori. The sensitivity of the UFT 300 was 90.3%, 94.5% and 96.2% at 1, 5 and 60 min respectively (specificity 100%). The Pyloritek and the UFT were comparable, but the CLO test was not reliable at 5 and 60 min. Conclusion, The UFT 300 test is comparable to the Pyloritek test, but the CLO test is significantly less sensitive at early time points. Reading test results at 1 min may increase false negative results, thereby decreasing sensitivity. Aliment Pharmacol Ther,31, 331,338 [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] 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. [source] Parathyroid hormone venous sampling prior to reoperation forprimary hyperparathyroidismANZ JOURNAL OF SURGERY, Issue 10 2003E. Estella Background: The surgical cure rate for primary hyperparathyroidismis greater than 95%. For those who have recurrent or persistentdisease, preoperative localization improves reoperation successrates. Selective parathyroid venous sampling (SPVS) for intact parathyroidhormone is particularly useful when non-invasive localization techniquesare negative or inconclusive. Methods: We present all known cases (n = 13)between 1994 and 2002 who had venous sampling for localization atour institution prior to reoperation for recurrent or persistentprimary hyperparathyroidism. Comparison was made with non-invasivelocalization procedures. Results of invasive and non-invasive localizationwere correlated with surgical findings. Results: Of the nine reoperated cases, eight had positive correlationsbetween SPVS and operative findings and histopathology. SPVS didnot reveal the parathyroid hormone source in one case with negativenon-invasive localization procedures. Comparisons between SPVS,computerized tomography (CT), and parathyroid scintigraphy (MIBI)as expressed in terms of true positive (TP), false positive (FP)and false negative (FN) were: SPVS , TP88.8%, FP 0%, FN 11.1%; CT , TP22.2%, FP 22.2%, FN 55.5%; and MIBI , TP33.3%, FP 0%, FN 66.6%. At least sevenof the nine operated cases have been cured; another remained normocalcaemic 2 weeksafter subtotal parathyroidectomy. Conclusion: In our institution SPVS has proven to be a valuabletool in cases with recurrent or persistent primary hyperparathyroidismand negative non-invasive localization procedures. [source] An Experimental Investigation of the Effects of Acknowledging False Negative and False Positive Errors on Clients' Cancer Screening Intentions: The Lesser of Two Evils?APPLIED PSYCHOLOGY: HEALTH AND WELL-BEING, Issue 2 2010Shoshana Shiloh Two studies investigated people's motivations for testing, and the influence of awareness of test inaccuracies, on their intentions to undergo cancer screening tests. Study 1 used a between-subjects design in which participants stated their intentions regarding one of several screening tests with equal accuracy but with either false negative, false positive, or unspecified errors. Study 2 used a within-subjects design in which participants indicated their intentions regarding each of those screening tests. In Study 1, intentions for testing were relatively high, affected by instrumental (illness prevention) motivations, and unaffected by type of error acknowledged. Individuals with higher emotional (reassurance seeking) motivations had lower intentions to uptake tests with false positive errors. In Study 2, intentions to uptake all tests were lower compared to Study 1, and were affected by emotional motivations. Participants preferred a test with unspecified errors over tests with specified errors, and, when forced to choose, preferred tests with false negative over false positive errors. Findings are discussed in relation to Error Management Theory and Self-Regulation Theory, emphasising the need to recognise motivations, affect, and framing as important factors in informed screening decisions. [source] Histologic changes associated with false-negative sentinel lymph nodes after preoperative chemotherapy in patients with confirmed lymph node-positive breast cancer before treatmentCANCER, Issue 12 2010Alexandra S. Brown MD Abstract BACKGROUND: A wide range of false-negative rates has been reported for sentinel lymph node (SLN) biopsy after preoperative chemotherapy. The purpose of this study was to determine whether histologic findings in negative SLNs after preoperative chemotherapy are helpful in assessing the accuracy of SLN biopsy in patients with confirmed lymph node-positive disease before treatment. METHODS: Eighty-six patients with confirmed lymph node-positive disease at presentation underwent successful SLN biopsy and axillary dissection after preoperative chemotherapy at a single institution between 1994 and 2007. Available hematoxylin and eosin-stained sections from patients with negative SLNs were reviewed, and associations between histologic findings in the negative SLNs and SLN status (true negative vs false negative) were evaluated. RESULTS: Forty-seven (55%) patients had at least 1 positive SLN, and 39 (45%) patients had negative SLNs. The false-negative rate was 22%, and the negative predictive value was 67%. The negative SLNs from 17 of 34 patients with available slides had focal areas of fibrosis, some with associated foamy parenchymal histiocytes, fat necrosis, or calcification. These histologic findings occurred in 15 (65%) of 23 patients with true-negative SLNs and in only 2 (18%) of 11 patients with false-negative SLNs (P = .03, Fisher exact test, 2-tailed). The lack of these histologic changes had a sensitivity and specificity for identifying a false-negative SLN of 82% and 65%, respectively. CONCLUSIONS: Absence of treatment effect in SLNs after chemotherapy in patients with lymph node-positive disease at initial presentation has good sensitivity but low specificity for identifying a false-negative SLN. Cancer 2010. © 2010 American Cancer Society. [source] Prospective comparison of [18F]fluorodeoxyglucose positron emission tomography with conventional assessment by computed tomography scans and serum tumor markers for the evaluation of residual masses in patients with nonseminomatous germ cell carcinomaCANCER, Issue 9 2002Christian Kollmannsberger M.D. Abstract BACKGROUND To assess the ability of [18F]fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET) to predict the viability of residual masses after chemotherapy in patients with metastatic nonseminomatous germ cell tumors (GCT), PET results were compared in a blinded analysis with computed tomography (CT) scans and serum tumor marker changes (TUM) as established methods of assessment. METHODS Independent reviewers who were blinded to each other's results evaluated the PET results and corresponding CT scan and TUM results in 85 residual lesions from 45 patients. All patients were treated within prospective clinical trials and received primary/salvage, high-dose chemotherapy with autologous blood stem cell support for primary poor prognosis disease or recurrent disease. PET results were assessed both visually and by quantifying glucose uptake (standardized uptake values). Results were validated either by histologic examination of a resected mass and/or biopsy (n = 28 lesions) or by a 6-month clinical follow-up after evaluation (n = 57 lesions). RESULTS F-18 FDG PET showed increased tracer uptake in 32 of 85 residual lesions, with 29 true positive (TP) lesions and three false positive (FP) lesions. Fifty-three lesions were classified by PET as negative (no viable GCT), 33 lesions were classified by PET as true negative (TN), and 20 lesions were classified by PET as false negative (FN). In the blinded reading of the corresponding CT scan and TUM results, 38 residual lesions were assessed correctly as containing viable carcinoma and/or teratoma. Forty-six lesions were classified as nonsuspicious by CT scan/TUM (33 TN lesions and 14 falsely classified lesions). PET correctly predicted the presence of viable carcinoma in 5 of these 14 and the absence of viable carcinoma in 3 of these 14 lesions. Resulting sensitivities and specificities for the prediction of residual mass viability were as follows: PET, 59% sensitivity and 92% specificity; radiologic monitoring, 55% sensitivity and 86% specificity; and TUM, 42% sensitivity and 100% specificity. The positive and negative predictive values for PET were 91% and 62%, respectively. The diagnostic efficacy of PET did not improve when patients with teratomatous elements in the primary tumor were excluded from the analysis. In patients with multiple residual masses, a uniformly increased residual F-18 FDG uptake in all lesions was a strong predictor for the presence of viable carcinoma. CONCLUSIONS F-18 FDG PET imaging performed in conjunction with conventional staging methods offers additional information for the prediction of residual mass histology in patients with nonseminomatous GCT. A positive PET is highly predictive for the presence of viable carcinoma. Other useful indications for a PET examination include patients with multiple residual masses and patients with marker negative disease. Cancer 2002;94:2353,62. © 2002 American Cancer Society. DOI 10.1002/cncr.10494 [source] A model of paediatric eye screening program for educatorsACTA OPHTHALMOLOGICA, Issue 2007N STOJANOVIC Purpose: Presentation of a paediatric eye screening program which is based on the educators' performance Methods: 4400 children(n1=2200 3-3 ½ y.o., n2=2200 4-6 y.o.),10 ophthalmologists and 20 teachers participated in this study.Children were tested for visual acuity(Va),using the NK test and manifest horizontal strabismus,using the Hirschberg test.Criteria for further evaluation:n1: Va<0.55 and/or manifest strabismus& in n2:Va<0.75and/or manifest strabismus Results: In n1=2200, doctors found:105 children(4.77%) appeared with Va<0.55, 1938 children(88.1%)with Va=0.55 and 157 children(7.13%)with Va>0.55. In n1 teachers found:191 children(8.68%) appeared with Va<0.55,1799 children(81.78%)with Va=0.55 and 210 children(9.54%)with Va >0.55. In (n1) doctors found:2111children(95.95%)were orthophoric,62 children(2.81%)were esotropic and 27 children(1,23%) were exotropic. Teachers found:2051 children(93.22%)were orthophoric, 106 children(4.81%) were esotropic and 43 children(1.97%)were exotropic. In n2=2200,doctors found:164 children(7.45%) appeared with Va<0.75,1695 children(77.05 %)with Va=0.75 and 341 children(15.5%)with Va>0.75. In n2, teachers found:160 children(7.27%)with Va<0.75,1639 children(74.50 %)with Va=0.75 and 401 children(18.22 %)with Va>0.75. In the same sample(n2), doctors found:2121 children(96.40%)were orthophoric, 62children(2.81%)were esotropic and 17 children(0.79%)were exotorpic.Teachers found:2041 children(92.77%)were orthophoric,64 children(2.90%)were esotropic and 95 children(4.32 %)were exotropic Conclusions: In a screening eye program false positive referrals are more welcome than false negative,especially in a very cost effective program as this one is. We recommend this model in countries where no paramedics as screeners exist [source] Neuroprotein s-100B , a useful parameter in paediatric patients with mild traumatic brain injury?ACTA PAEDIATRICA, Issue 10 2009C Castellani Abstract Aims:, To examine the correlation of S-100B to cranial computerized tomography (CCT) scan results in children after mild traumatic brain injury (MTBI). Methods:, One hundred and nine paediatric patients (0,18 years) with MTBI were included in this prospective single-centre study. Serum was collected within 6 h of trauma for determination of serum S-100B. The upper reference of S-100B was set to 0.16 ,g/L. A CCT scan was performed in all patients and the results were correlated to the S-100B values. Results:, Computerized tomography was abnormal in 36 patients showing intracerebral haemorrhages and/or skull fractures. Serum S-100B level was significantly higher in patients with a pathological condition as shown in CT scan results (p = 0.003). There were no false negative, but 42 false positive test results for S-100B. This resulted in a sensitivity of 1.00, specificity of 0.42, positive predictive value of 0.46 and negative predictive value of 1.00. An area under the receiver operating curve of 0.68 was calculated. Conclusion:, S-100B is a valuable tool to rule out patients with pathological CCT findings in a collective of paediatric patients with MTBI. Elevations of S-100B do not necessarily lead to a pathological finding in the CT scan, but values below the cut-off safely rule out the evidence of intracranial lesions. [source] Implications of the absence of st-segment elevation in lead V4R in patients who have inferior wall acute myocardial infarction with right ventricular involvementCLINICAL CARDIOLOGY, Issue 3 2001Masami Kosuge M.D. Abstract Background: ST-segment elevation of ± 1.0 mm in lead V4R has been shown to be a reliable marker of right ventricular involvement (RVI), a strong predictor of a poor outcome in patients with inferior acute myocardial infarction (IMI). However, patients with no ST-segment elevation in lead V4R despite the presence of RVI have received little attention. Hypothesis: The study was undertaken to study the clinical features of patients with no ST-segment elevation in lead V4R despite the presence of RVI, which means false negative, as such patients have received little attention in the past. Methods: We studied 62 patients with a first IMI. who had total occlusion of the right coronary artery (RCA) proximal to the first right ventricular branch and successful reperfusion within 6 h from symptom onset, to examine the implications of the absence of ST-segment elevation in lead V4R despite the presence of RVI. Results: A standard 12-lead electrocardiogram (ECG) and right precordial ECG (lead V4R) were recorded on admission, and three posterior chest ECGs (leads V7 to V9) were additionally recorded in 34 patients. Patients were classified according to the absence (Group 1, n = 18) or presence (Group 2, n = 44) of ST-segment elevation of ± 1.0 mm in lead V4R on admission. Patients in Group 1 had a greater ST-segment elevation in leads V7 to V9 (2.9 ± 2.4 vs. 1.4 ± 3.0 mm, p < 0.05), a higher frequency of a dominant RCA (defined as the distribution score , 0.7) (72 vs. 11%, p < 0.001), and a higher peak creatine kinase level (3760 ±; 1548 vs. 2809 ± 1824 mU/ml, p < 0.05) than those in Group 2. Conclusions: In patients with IMI caused by the occlusion of the RCA proximal to the first right ventricular branch, no ST-segment elevation in lead V4R can occur because of concomitant posterior involvement. In such patients, the incidence of RVI may be underestimated on the basis of ST-segment elevation in lead V4R. [source] The role of desmopressin in bilateral and simultaneous inferior petrosal sinus sampling for differential diagnosis of ACTH-dependent Cushing's syndromeCLINICAL ENDOCRINOLOGY, Issue 1 2007Marcio Carlos Machado Summary Objective, ,Bilateral inferior petrosal sinus sampling (BIPSS) with corticotrophin-releasing hormone (CRH) stimulation is currently the gold standard test for the differential diagnosis of ACTH-dependent Cushing's syndrome. Reports on the use of desmopressin in this approach are limited. The aim of this study was to evaluate the use of desmopressin during BIPSS in a cohort of patients with ACTH-dependent Cushing's syndrome. Design, ,A retrospective case-record study. Patients,, Fifty-six patients with confirmed ACTH-dependent Cushing's syndrome underwent BIPSS with desmopressin stimulation when presenting negative pituitary tumour imaging. Measurements,, Central to peripheral (CEN:PER) ACTH gradient, lateralization of the ACTH source and surgical tumour confirmation were evaluated. Results,, A CEN:PER ACTH gradient was found in 40 patients under basal conditions (CEN:PER , 2) and in 47 patients after desmopressin stimulation (CEN:PER , 3). Ectopic ACTH-producing tumours (three lung carcinoid tumour, one thymus carcinoid tumour and one thymus hyperplasia) were confirmed in five out of nine patients without the CEN:PER ACTH gradient, and four cases were false negative for Cushing's disease. Lateralization (IPS:IPS , 1·4) was observed in 80·8% of patients under basal conditions (38/47) and in 97·8% after desmopressin (46/47), and it was surgically confirmed in 78·7%. There were no false-positive cases. Sensitivity and specificity were 92·1% and 100%, respectively. Conclusions, ,Desmopressin improves the differential diagnosis of ACTH-dependent Cushing's syndrome by amplifying the CEN:PER and IPS:IPS ACTH gradients, and is therefore a useful ACTH secretagogue in BIPSS. [source] The Neutralizer: a self-configurable failure detector for minimizing distributed storage maintenance costCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 2 2009Zhi Yang Abstract To achieve high data availability or reliability in an efficient manner, distributed storage systems must detect whether an observed node failure is permanent or transient, and if necessary, generate replicas to restore the desired level of replication. Given the unpredictability of network dynamics, however, distinguishing permanent and transient failures is extremely difficult. Though timeout-based detectors can be used to avoid mistaking transient failures as permanent failures, it is unknown how the timeout values should be selected to achieve a better tradeoff between detection latency and accuracy. In this paper, we address this fundamental tradeoff from several perspectives. First, we explore the impact of different timeout values on maintenance cost by examining the probability of their false positives and false negatives. Second, we propose a self-configurable failure detector called the Neutralizer based on the idea of counteracting false positives with false negatives. The Neutralizer could enable the system to maintain a desired replication level on average with the least amount of bandwidth. We conduct extensive simulations using real trace data from a widely deployed peer-to-peer system and synthetic traces based on PlanetLab and Microsoft PCs, showing a significant reduction in aggregate bandwidth usage after applying the Neutralizer (especially in an environment with a low average node availability). Overall, we demonstrate that the Neutralizer closely approximates the performance of a perfect ,oracle' detector in many cases. Copyright © 2008 John Wiley & Sons, Ltd. [source] Information derived from sensitization test methods: test sensitivity, false positives and false negativesCONTACT DERMATITIS, Issue 1 2007David A. Basketter Predictive toxicology tests for the prospective identification of skin-sensitizing chemicals are well known and have been used for many years. However, of these, only the local lymph node assay (LLNA) has actually undergone formal independent assessment to determine the accuracy of the predictions, particularly with respect to the likelihood of false positives and false negatives. Often, efforts to increase the sensitivity of a test (reducing false negatives) tend to increase the number of false positives. In this short review, these issues are discussed in particular relation to the 3 predictive tests available in regulatory toxicology, the guinea-pig maximization test, the occluded patch test of Buehler and the LLNA. A key perspective is that no predictive test is without limitations; having a good appreciation of these limitations is necessary for making the best use of the information derived from these methods. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||