Search results for "False Negative Reactions"
showing 10 items of 21 documents
Children may not benefit from neuroblastoma screening at 1 year of age. Updated results of the population based controlled trial in Germany
2003
Neuroblastoma is the second most frequent malignancy in childhood. We investigated whether screening for neuroblastoma at 1 year of age reduces the incidence of metastatic disease or mortality. Screening was offered in 6 of the 16 German states from 1995 to 2000 with the remaining states serving as controls. We studied 2,581,188 children in the screening area born between 1994 and 1999 and 2,117,600 in the control area. We compared mortality from neuroblastoma and the incidence of disseminated disease in the two groups. The screened group and the control group had similar rates of stage 4 neuroblastoma and mortality due to neuroblastoma. Comparison of the screened group and the control area…
Freezing Induces Biased Results in the Molecular Detection of Flavobacterium columnare
2006
ABSTRACT Specific PCR detection and electron microscopy of Flavobacterium columnare revealed the risk of false-negative results in molecular detection of this fish pathogen. Freezing and thawing destroyed the cells so that DNA was for the most part undetectable by PCR. The detection of bacteria was also weakened after prolonged enrichment cultivation of samples from infected fish.
Detection of 9-Tetrahydrocannabinol and Amphetamine-Type Stimulants in Oral Fluid Using the Rapid Stat Point-of-Collection Drug-Testing Device
2010
The Rapid Stat assay, a point-of-collection drug-testing device for detection of amphetamines, cannabinoids, cocaine, opiates, methadone, and benzodiazepines in oral fluid, was evaluated for cannabis and amphetamine-type stimulants. The Rapid Stat tests (n = 134) were applied by police officers in routine traffic checks. Oral fluid and blood samples were analyzed using gas chromatography-mass spectrometry (GC-MS) for Delta(9)-tetrahydrocannabinol, amphetamine, methamphetamine, methylenedioxymethamphetamine, methylenedioxyethylamphetamine, and methylenedioxyamphetamine. The comparison of GC-MS analysis of oral fluid with the Rapid Stat results for cannabis showed a sensitivity of 85%, a spec…
On the power and the systematic biases of the detection of chromosomal inversions by paired-end genome sequencing
2013
One of the most used techniques to study structural variation at a genome level is paired-end mapping (PEM). PEM has the advantage of being able to detect balanced events, such as inversions and translocations. However, inversions are still quite difficult to predict reliably, especially from high-throughput sequencing data. We simulated realistic PEM experiments with different combinations of read and library fragment lengths, including sequencing errors and meaningful base-qualities, to quantify and track down the origin of false positives and negatives along sequencing, mapping, and downstream analysis. We show that PEM is very appropriate to detect a wide range of inversions, even with …
Ultrasonography and alpha-fetoprotein in diagnosis of hepatocellular carcinoma in cirrhosis
1988
The accuracy of ultrasound (US) and alpha-fetoprotein (AFP) in the diagnosis of hepatocellular carcinoma (HCC) in 363 patients with cirrhosis (C) and a clinical suspicion of HCC was assessed. The ultrasonographic patterns of HCC and their relationship with AFP values were analyzed. Echographic patterns were distributed as follows: 47 patients had sonodense lesions; 30 patients had hypoechoic lesions; 47 had mixed-pattern lesions, and in four patients focal dilated intrahepatic bile ducts were demonstrated. The sensitivity of US was 90%; specificity was 93.3%. Serum AFP level greater than or equal to 500 ng/ml (RIA) was the first clue to the diagnosis in 71 patients (48.6%); specificity was …
False-negative results by polymerase chain reaction due to contamination by glove powder
1992
The polymerase chain reaction (PCR) technique has become an important, widely employed method for the detection and quantitation of the nucleic acid sequences used in the diagnosis and monitoring of genetic and infectious diseases. Much attention has been directed at the problem of false-positive PCR results, which are generally attributed to low-level laboratory contamination of amplified sequences ("carryover"). In contrast, few investigators have commented on the somewhat less frequent, but equally problematic, false-negative PCR results. Investigation of the source of sporadic false-negative PCR reactions found that glove powder, inadvertently introduced into tubes when gloves are chang…
The impact of age on prevalence of positive skin prick tests and specific IgE tests
2011
SummaryAging is associated with modifications of the immune system, defined as immunosenescence. This could contribute to a reduced prevalence of allergic disease in the elderly population. In this regard, atopy has rarely been considered in the clinical assessment of the geriatric respiratory patient. This article is a review of the available literature assessing the impact of age on atopy. In the majority of papers, we found a lower prevalence of atopy in the most advanced ages, both in healthy subjects and in individuals affected by allergic respiratory diseases. Unfortunately, no large, longitudinal studies performed in the general population have been conducted to further explore this …
Diagnostic efficacy of the ELISA test for the detection of deamidated anti-gliadin peptide antibodies in the diagnosis and monitoring of celiac disea…
2009
Background and Aim: We evaluated the diagnostic performance of an ELISA test for anti-gliadin IgA and IgG antibodies, which uses synthetic deamidated gliadin peptides (anti-gliadin antibodies, AGAs) as coating; the results were compared with a test that uses extracted gliadin (AGAe). Methods: The study was conducted on the sera of 144 patients suffering from celiac disease (CD), including 20 patients with IgA deficiency and 9 who were following a gluten-free diet (GFD), and 129 controls. Results: In the 115 CD patients (without IgA deficiency), the sensitivity of AGAe IgA and IgG was 32.2 and 60.9%, whereas that of AGAs IgA and IgG was 59.1 and 72.2%. The specificity for AGAe IgA and IgG, a…
Steatocrit test after a standard fatty meal: A new simple and sensitive test to detect malabsorption
1991
The steatocrit test, a simple semiquantitative method for determining fat content in stool, was performed after a standard fatty meal to detect malabsorption in patients with celiac disease. Thirty-seven children (mean age 2.6 +/- 2.1 years) with total atrophy of the intestinal villi and 79 controls (mean age 3.5 +/- 2.8 years) were studied. All subjects underwent a small-bowel biopsy, a D-xylose absorption test, a rapid triglyceride absorption test, and a steatocrit determination first on an uncontrolled diet and then again after a standard fatty meal. The steatocrit test after a fatty meal did not detect any false-positive or false-negative results, while the D-xylose test showed two fals…
Negative Effect of Ranitidine on The Results of Urea Breath Test for The Diagnosis of Helicobacter Pylori
2001
In analogy with proton pump inhibitors, H2-antagonists may also be responsible for false-negative results on urea breath test for the detection of Helicobacter pylori. In this study we assessed the frequency and duration of false-negative urea breath tests in patients given different doses of ranitidine.A total of 120 consecutive dyspeptic patients infected with H. pylori on the basis of concomitant positive results of CLO-test, histology and urea breath test were recruited for this prospective, open, parallel-group study performed in an urban university gastroenterological clinic. They were randomized to receive an acute treatment with either ranitidine 300 mg once a day in the evening, ra…