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At least 127 records · Page 7Linked to original sources

PubMed2005

Simultaneous detection of hepatitis C virus (HCV) core antigen and anti-HCV antibodies improves the early detection of HCV infection.

To evaluate whether a new enzyme immunoassay developed for the simultaneous detection of hepatitis C virus (HCV) core antigen (Ag) and anti-HCV antibodies (anti-HCV Ab) (Monolisa HCV Ag/Ab ULTRA; Bio-Rad) could improve the early detection of HCV infection, we compared its sensitivity to that of anti-HCV, HCV core Ag, and HCV RNA assays. The populations studied included 12 blood donor samples positive for HCV RNA and HCV core Ag but negative for anti-HCV antibodies and 23 hemodialysis patients who developed anti-HCV Ab (seroconversion) during the follow-up. From these 23 individuals, 83 samples sequentially collected prior to seroconversion and 108 samples collected after seroconversion were tested. Six of 12 blood donations were positive by the HCV Ag/Ab assay. In the hemodialysis cohort, the 24 HCV RNA-negative samples were negative by the HCV Ag/Ab assay and 23 of the 59 HCV RNA-positive samples (39%) were positive. The HCV Ag/Ab assay detected HCV infection on average 21.6 days before the most sensitive antibody assay. The HCV Ag/Ab assay did not detect HCV infection as early as the HCV RNA assay (mean delay, 30.3 days) or HCV Ag assay (mean delays, 27.9, and 16.3 days by the HCV core Ag quantification assay and the HCV Ag blood screening assay, respectively). This new assay provides a notable improvement for the early detection of HCV infection during the so-called window period compared with anti-HCV Ab assays and could be a useful alternative to HCV RNA detection or HCV core Ag assays for diagnosis or blood screening when nucleic acid technologies or HCV core Ag detection are not implemented.

Blood Donors↗

PubMed2004

CT colonography with computer-aided detection: automated recognition of ileocecal valve to reduce number of false-positive detections.

The ileocecal valve (ICV) is a common cause of false-positive detections of polyps at computed tomographic (CT) colonography with computer-aided detection (CAD). The authors developed a CAD algorithm for differentiating the ICV from a true polyp and evaluated this algorithm by using two colonoscopy-confirmed CT colonography data sets. Data sets 1 and 2 consisted of the data obtained at CT colonographic examinations performed in 20 and 40 patients, respectively. Forty of these patients had at least one polyp 1 cm or larger. For data set 1, the proposed ICV recognition algorithm eliminated three of nine (33%; 95% confidence interval [CI]: 8%, 70%) false-positive CAD detections that were attributable to the ICV and none of the true-positive polyp detections. For data set 2, with use of identical parameters, the algorithm eliminated 11 of 18 (61%; 95% CI: 36%, 83%) false-positive detections that were attributable to the ICV and none of the true-positive detections. The thresholds used to recognize the ICV were a mean internal CT attenuation of less than -124 HU and a volume of greater than 1.5 cm(3). The proposed algorithm successfully recognized the ICV and eliminated it in some cases. This result is clinically important because, by reducing the frequency of a common cause of false-positive detections, this algorithm may improve the efficiency of physicians who use CAD.

Adult↗

PubMed1998

Automated detection of breast carcinomas not detected in a screening program.

PURPOSE: To investigate the possibility of automated detection of early signs of cancer that were not detected in a breast cancer screening program. MATERIALS AND METHODS: A set of 75 mammograms (in 65 women) with subtle circumscribed masses, stellate lesions, and architectural distortions that were not detected in a screening program by two radiologists was assembled and extended with 142 normal mammograms (contralateral mammograms in the same 65 women). An automated system for the detection of circumscribed masses and stellate lesions was applied to this set. RESULTS: In 22 (34%) of 65 cases, an early sign of cancer was detected at a specificity of one false-positive finding per image. At a specificity of three false-positive findings per image, 39 (60%) of the cancers were detected. Of the tumors that were classified as screening errors, seven (50%) were found at a specificity of 0.5 false-positive finding per image. CONCLUSION: A substantial proportion of cancers that were missed in a screening program, despite double reading, were found with this detection method at less than one false-positive finding per image.

Algorithms↗

PubMed2004

Alaris AEP monitor's "Click Detection" does not help to detect inadvertent disconnection of headphones during anesthesia.

UNLABELLED: Auditory evoked potentials (AEP) can be suppressed by anesthetics dose dependently, but may fail to be registered because of the absence of adequate auditory stimuli. The Alaris AEP monitor includes the "Click Detection" (CD) (generating the message "NO AEP" or "LOW AEP") to detect the loss of auditory stimuli. We investigated the accuracy of the CD in 17 patients awake (AWAKE) and during anesthesia (ANESTHESIA) with accurately placed headphones (HP) and after disconnected HP (No HP) over 5 min each, respectively. Alaris AEP ARX index, CD, and Bispectral Index were recorded each minute. Changes were evaluated with the Friedman and Wilcoxon test. Sensitivity (SEN) and specificity (SPE) and receiver operating characteristic curve were analyzed for the accuracy of the CD. During AWAKE after disconnection of the HP, Alaris AEP ARX index decreased significantly (P < 0.05). The CD was able to detect No HP after 2 min with a SEN of 88% and a SPE of 97%. During ANESTHESIA, no changes were found after HP disconnection. CD detected No HP with a SEN of 100% and a SPE of 20%. The CD of the Alaris AEP monitor is not able to detect unnoticed disconnection of HP during ANESTHESIA. IMPLICATIONS: Signal transmission of auditory evoked potentials can be suppressed by anesthetics, but also by disconnection of headphones. In the present study, we demonstrate that even the Alaris AEP monitor with the very new feature "Click Detection" was not able to detect the loss of headphones during general anesthesia with propofol and remifentanil.

Acoustic Stimulation↗

PubMed2000

Visual signal detection in structured backgrounds. IV. Figures of merit for model performance in multiple-alternative forced-choice detection tasks with correlated responses.

Many investigators are currently developing models to predict human performance in detecting a signal embedded in complex backgrounds. A common figure of merit for model performance is d', an index of detectability that can be mathematically related to the proportion correct (Pc) when the responses of the model are Gaussian distributed and statistically independent. However, in many multiple-alternative forced-choice (MAFC) detection tasks, the target appears in one of M different locations within an image. If the image contains slow spatially varying luminance changes (low-pass noise), the pixel luminance values at the possible signal locations are correlated and therefore the model/human responses to the different locations might also be correlated. We investigate the effect of response correlations on model performance and compare different figures of merit for these conditions. Our results show that use of the standard d' index of detectability assuming statistical independence can lead to erroneous underestimates of Pc and misleading comparisons of models. We introduce a novel figure of merit d'(r) that takes into account response correlations and can be used to accurately estimate Pc. Furthermore, we show that d'(r) can be readily related to the standard index of detectability d' by d'(r) = d'/square root of (1 - r), where r is the correlation between the responses in any MAFC detection task. We illustrate the use of the theory by computing figures of merit for two linear models detecting a signal in one of four locations within medical image backgrounds.

Choice Behavior↗

PubMed2000

[Detection of hepatitis C virus RNA in the tissue of hepatocellular carcinoma by multiple detection system].

OBJECTIVE: Detection of hepatic HCV RNA in hepatocellular carcinoma (HCC) is difficult, since its expression is very low. Several techniques have been established. However, false positive and negative rates still exist. In this study, we applied several conventional and recently developed detection systems to determine the exact effect of HCV RNA on the development of RCC. METHODS: Immunohistochemistry for HCV core antigen and in situ hybridization for HCV RNA had been performed in 39 cases of HCC. IS-RT-PCR was applied for detection and localization of HCV RNA. We extracted microdissected liver tissues to detect HCV RNA separately in cancerous and pericancerous tissues so that the microscopic origin of the amplicons could be controlled. The serological tests including ELISA and RT-PCR for HCV also were performed in all cases. RESULTS: The positive rate by ELISA (30.8%) was not always consistent with that by RT-PCR(43.6%)from serum samples. The latter was much more sensitive and accurate to reflect existence of HCV RNA. Immunohistochemistry showed expression of RCV core antigen in 15 of 39 HCC cases. In pericancerous tissues, the signals were mainly localized in the cytoplasm of hepatocytes. However, translocated expression of HCV core protein was observed in the nuclei of tumor cells, the translocated rate was 73.3%. According to IS-RT-PCR, the positive signals were located mainly in the cytoplasm of cancer cells, the positive rate in HCC was 53.8%, expression of HCV RNA, serum HCV RNA level was detected to be low or negative. This suggested that serum HCV RNA was not always a good reflection of hepatic HCV RNA in HCC tissues. The microdissection RT-PCR described here gave an equal positive rate (59.0%) of HCV RNA in cancerous and pericancerous tissues. CONCLUSIONS: The high detection rate of HCV RNA in HCC specimens even from seronegative patients confirms the important role of HCV RNA during malignant transformation. IS-RT-PCR is a good detection and localization method to visualize HCV RNA in HCC tissues. The microdissection RT-PCR method has a distinct advantage and we anticipate this method will provide an important evidence to determine whether HCV play a direct or indirect role in hepatocarcinogenesis.

Adult↗

PubMed2002

Physicians as detectives in detective fiction of the 20th century.

BACKGROUND: Surprisingly few detectives are physicians in 20th-century detective fiction. METHODS: Potential books with physician-detective characters were located by pursuing all mentions of characters referred to as 'Doctor" in any of several reference materials pertaining to mystery and detective fiction. RESULTS: As a result of the search, 53 authors whose detective characters are physicians were found. Examination of novels by these authors revealed that early in the 20th century, physicians applied their own specialized scientific knowledge to detection. Mid-century physicians worked by intuition. In the 1990s, science returned to detective fiction in the form of standard forensic procedure, and the level of violence dramatically increased. CONCLUSION: The relation between science and violence at the end of the 20th century may not be accidental.

Crime↗

PubMed1993

Early detection of prostate cancer following repeated examinations by multiple modalities: results of the American Cancer Society National Prostate Cancer Detection Project.

The American Cancer Society National Prostate Cancer Detection Project (ACS-NPCDP) is a multicenter, interdisciplinary demonstration project to assess the impact on early detection of transrectal ultrasound (TRUS), prostate-specific antigen (PSA), and digital rectal examination (DRE). Preliminary data are available from the first 3-5 y of planned observation. The results show declining rates of detection for each succeeding examination. Cancer detection rates are highly dependent on age. The positive predictive value of a solitary examination is low regardless of modality, but any combination of positive results has a much better predictive value. The cancers detected were predominantly clinically localized tumors, and detection of advanced stage cancer was uncommon after the initial examination. Radical prostatectomy was the most common form of treatment. These findings have implications for prostate cancer early detection guidelines and practice.

Aged↗

PubMed1994

Detection of autoantibodies to amylase by ELISA: comparison of detection of macroamylase and free autoantibody.

New ELISAs for detecting macroamylase or free autoantibodies to amylase were tested with 48 samples that had been characterized by gel chromatography and electrophoresis. The macroamylase ELISA, with anti-IgG or anti-IgA for detection, detected macroamylase in 28 of 33 samples known to contain macroamylase (85% sensitivity), whereas the ELISA for free autoantibody to amylase was positive for only 11 samples. Specificities of both ELISAs were 93%. Among 28 true positives detected with the macroamylase ELISA, 22 contained IgA, 3 contained IgG, and 3 contained both immunoglobulins. Detection of IgM added no true positives. ELISA responses (y) were proportional to log [macroamylase concentration by chromatography (x)] from 0 to 1200 U/L: y = 5.15 x + 1.66; r = 0.72; Sy x = 1.65. As new tools for detecting macroenzymes consisting of enzyme-autoantibody complexes, the ELISAs show that some autoantibodies are detected more sensitively as antibody-antigen complexes than as free antibody.

Amylases↗

PubMed1996

Screening of antipsychotic drugs by wide-bore capillary gas chromatography with nitrogen phosphorus detection--detection levels in plasma.

The detection levels of 12 antipsychotic drugs as ascertained from drug screening were examined in order to use the screening results effectively for treatment of patients or medico-legal examinations in cases of poisoning. Wide-bore capillary gas chromatography with nitrogen phosphorus detection was used for the analysis. The detection limits of drugs in plasma using 3 extraction procedures, single-solvent, 3-step solvent and solid-phase extractions were 50-100 ng/ml, 10-200 ng/ml and 5-50 ng/ml, respectively. The detection limits were compared with blood levels previously reported in the literature. Only 4 drugs were detected at the therapeutic level, thioridazine, floropipamide, sultopride and oxypertine using the single-solvent extraction procedure. Using the 3-step solvent extraction procedure, chlorpromazine, levomepromazine and zotepine in addition to the above 4 drugs were detected. Using the solid-phase extraction procedure, 8 of 12 drugs were able to be detected at the therapeutic level, with the exception of perphenazine, haloperidol, bromperidol and nemonapride. These data were proved to be useful for a rapid forensic diagnosis.

Antipsychotic Agents↗

PubMed1996

Mutation detection in Machado-Joseph disease using repeat expansion detection.

BACKGROUND: Several neurological disorders have recently been explained through the discovery of expanded DNA repeat sequences. Among these is Machado-Joseph disease, one of the most common spinocerebellar ataxias (MJD/SCA3), caused by a CAG repeat expansion on chromosome 14. A useful way of detecting repeat sequence mutations is offered by the repeat expansion detection method (RED), in which a thermostable ligase is used to detect repeat expansions directly from genomic DNA. We have used RED to detect CAG expansions in families with either MJD/SCA3 or with previously uncharacterized spinocerebellar ataxia (SCA). MATERIALS AND METHODS: Five MJD/SCA3 families and one SCA family where linkage to SCA1-5 had been excluded were analyzed by RED and polymerase chain reaction (PCR). RESULTS: An expansion represented by RED products of 180-270 bp segregated with MJD/SCA3 (p < 0.00001) in five families (n = 60) and PCR products corresponding to 66-80 repeat copies were observed in all affected individuals. We also detected a 210-bp RED product segregating with disease (p < 0.01) in a non-SCA1-5 family (n = 16), suggesting involvement of a CAG expansion in the pathophysiology. PCR analysis subsequently revealed an elongated MJD/SCA3 allele in all affected family members. CONCLUSIONS: RED products detected in Machado-Joseph disease families correlated with elongated PCR products at the MJD/SCA3 locus. We demonstrate the added usefulness of RED in detecting repeat expansions in disorders where linkage is complicated by phenotyping problems in gradually developing adult-onset disorders, as in the non-SCA1-5 family examined. The RED method is informative without any knowledge of flanking sequences. This is particularly useful when studying diseases where the mutated gene is unknown. We conclude that RED is a reliable method for analyzing expanded repeat sequences in the genome.

Alleles↗

PubMed1996

[Solid phase technique versus gel centrifugation for detection of erythrocyte antibodies--a prospective study comparison the 2 antibody detection tests].

AIM: To define differences of specifity and sensitivity between a solid phase- and a gel centrifugation test for detection of irregular erythrocyte antibodies. STUDY DESIGN: 3052 blood samples were screened for erythrocyte antibodies (AB) by gel centrifugation [ID-System, (ID) 37 degrees C Bromelin and indirect antiglobulin test with LISS (IAT)] and a solid phase antiglobulin test [Capture-R Ready Screen (CR)] in a prospective study. Identical test cells were used as immobilized monolayer in CR and as 1%-suspension in ID. Additionally, 42 sera with antibodies reacting in both tests were titered geometrically in both techniques. RESULTS: In 79 (2.6%) of all sera tested, irregular erythrocyte antibodies were detected. 64 (81%) of these positive sera were detected by both tests, 73 (92.3%) by ID and 70 (88.4%) by CR. 6 sera with AB (7.6%) were positive only with CR (1 Ce, 1 E, 1 Leb, 1 C, 1 D, 1 Cob) and 9 (11.4%) only with ID (4 Lea, 1 Fya, 1 C, 2 P1, 1 D). Seven AB solely detected in ID only reacted in the bromelin test, besides an anti-Fya, which was an IgM antibody. The titration of IgG antibodies showed a slightly higher sensitivity of the CR (less than one titre step). The ID showed clearly more unspecific reactions (1.1%) than the CR (0.5%). DISCUSSION: The antibody screening with the ID proved to detect more AB than the CR (mainly due to certainly irrelevant "enzyme only" AB). On the other hand, relevant IgG AB were detected more sensitive by the CR. Unspecific reactions appeared clearly more often in ID, predominantly when using the bromelin test. Missing a strong IgM anti-Fya in the CR is certainly a concern because of its assumed haemolytic activity. Therefore CR for antibody screening should always be combined with a method for crossmatching that safely detects IgM antibodies which are relevant for transfusion.

Blood Group Antigens↗

PubMed1991

The roles of deception, intention to deceive, and motivation to avoid detection in the psychophysiological detection of guilty knowledge.

The present study focused on electrodermal differentiation between relevant and neutral items in the Guilty Knowledge paradigm. Three factors were varied in a between-subjects design. The role of deception was examined by varying the type of verbal answer to the questions ("yes," "no," and remaining silent). The intention to deceive factor was examined by contrasting subjects told to delay their answer ("yes" or "no") with those told to produce their answer immediately. Finally, motivation to avoid detection was manipulated by having half the subjects monetarily rewarded for an important (ego relevant) detection task (high motivation), whereas the remaining subjects were neither rewarded nor told that the task was important. The results indicated that a deceptive answer ("no") to the relevant question was associated with an increased differential skin conductance responsivity, but better than chance detection rates were obtained with truthful ("yes") and silent conditions. Equal and significant detection rates were observed when the responses were computed immediately following question presentation, whether the subjects had answered immediately or had delayed their answers. In contrast, differential electrodermal responsivity to the delayed answers was markedly attenuated. The motivation factor had no main or interactive effects on differential responsivity. The present results, together with those obtained in previous studies, suggest that whereas deception is neither a necessary nor a sufficient condition for psychophysiological detection, it may facilitate detection. Possible mechanisms through which such a facilitation could occur were considered.

Adult↗

PubMed1975