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At least 649 records · Page 36Linked to original sources
PubMed2006

[Study on the development of a real-time quantitative polymerase chain reaction assay to detect Rickettsia].

OBJECTIVE: To develop a real-time quantitative polymerase chain reaction(PCR) assay for detecting Rickettsia rickettsii. METHODS: The primers and TaqMan-MGB probe were designed according to the ompB gene of R. rickettsii. A DNA fragment of ompB gene amplified from R. rickettsii by PCR was used as a standard template for the development of the method. RESULTS: 5 copies of ompB fragments of R. rickettsii were detected. The genomic DNA of R. rickettsii was detected by the developed quantitative PCR assay. However, the genomic DNA from another rickettsial or bacterial agent was not determined. Through this developed method, the positive results were obtained from the animals and cells, artificially infected with R. rickettsii. CONCLUSION: The real-time quantitative PCR assay seemed to be highly sensitive and specific which might be used to rapidly detect R. rickettsia DNA in various samples and to early diagnose patients infected by R. rickettsii.

DNA Primers↗
PubMed1995

Human efficiency for recognizing and detecting low-pass filtered objects.

Recently, Tjan, Braje, Legge and Kersten [(1995) Vision Research, 35, 3053-3069] found that human efficiency for object recognition was less than 10%, indicating that humans fail to use much of the information available to an ideal observer. We examine two explanations for these low efficiencies: (1) humans are inefficient in using high spatial-frequency information; and (2) humans are inefficient in detecting image samples. We tested the first possibility by measuring human efficiency for recognizing low-pass filtered objects, rendered as line drawings and silhouettes, in luminance noise. Efficiency did not improve when high frequencies were removed, and the first explanation was rejected. We tested the second explanation by comparing efficiencies for object detection and recognition. Recognition efficiency was higher than detection efficiency for silhouettes but not line drawings, showing that detection efficiency does not place a ceiling on recognition efficiency. The results indicate that human vision is designed to extract image features, such as contours, that enhance recognition. A computer simulation suggests that this can occur if the observer views the world through a band-pass spatial-frequency channel.

Algorithms↗
PubMed2005

ECG-gated 16-MDCT of the coronary arteries: assessment of image quality and accuracy in detecting stenoses.

OBJECTIVE: The aim of this study was to investigate image quality and diagnostic accuracy in detecting coronary artery lesions using a 16-MDCT scanner. MATERIALS AND METHODS: Thirty-seven patients (28 men, nine women) underwent unenhanced helical CT and MDCT angiography of the coronary arteries. After patients received oral beta-blocker medication, CT scans were obtained during a single breath-hold with a 16-MDCT scanner using ECG-gating (0.75-mm collimation, 2.8-mm table feed/rotation, 0.42-sec rotation time). The image quality was assessed in terms of artifacts and segment visibility by two reviewers. Stenosis severity was compared with the results of conventional invasive coronary angiography. RESULTS: The data evaluation of the image quality was based on a total of 488 segments, of which 380 segments were considered to have diagnostic image quality. One hundred eight segments (22.1%) could not be sufficiently evaluated because of severe calcifications (35 segments) and motion artifacts (73 segments). The mean calcium score (Agatston score equivalent [ASE]) was 524.3 +/- 807.6. Twenty-eight (75.7%) of the 37 patients had an ASE of less than 1,000 (mean ASE, 90.8 +/- 152.3 [SD]), and nine (24.3%) patients had an ASE of 1,000 or greater (mean ASE, 1,761.0 +/- 637.6). For detecting lesions 50% or greater (without any exclusion criteria), the overall sensitivity, specificity, positive predictive value, and negative predictive value were 59%, 87%, 61%, and 87%, respectively. When limiting the number of patients to those with a calcium score of less than 1,000 ASE, the threshold-corrected sensitivity for lesions 50% or greater was 93%; specificity, 94%; positive predictive value, 68%; and negative predictive value, 99%. CONCLUSION: In patients with no or moderate coronary calcification, MDCT of coronary arteries using 16-MDCT technology allows the reliable detection of coronary artery stenoses with high diagnostic accuracy. Obtaining an initial unenhanced scan was found to be mandatory to avoid performing useless examinations in patients with severe calcifications.

Adrenergic beta-Antagonists↗
PubMed1999

Does open biopsy before mastectomy affect the prevalence of so-called axillary lymph node micrometastases detected immunohistochemically.

OBJECTIVE: To determine the effect of a previous open biopsy on the presence of immunohistochemically detected micrometastases, particularly single cells, in axillary lymph nodes in patients with "node-negative" invasive breast carcinoma. METHODS: Node-negative breast cancer patients were divided into group 1 (diagnostic frozen-section biopsy with immediate mastectomy and axillary dissection) and group 2 (open surgical biopsy with temporally delayed mastectomy and axillary dissection). Archival slides of lymph nodes were examined and new sections stained with hematoxylin-eosin and immunohistochemically with a cytokeratin cocktail to detect micrometastases. RESULTS: Four (12%) of 33 patients had unequivocal lymph node metastases on additional hematoxylin-eosin sections (3 cases) or review of original material (1 case). Immunohistochemical analysis contributed additional data in only 1 group 2 patient. In this case a single strongly keratin-positive sinus-based cell was detected in 1 lymph node. CONCLUSION: The study suggests that previous surgical biopsy of the breast does not increase the incidence of immunohistochemically detected keratin positive cells in axillary lymph nodes.

Biopsy↗
PubMed2003

The relationship between change detection and recognition of centrally attended objects in motion pictures.

Observers typically detect changes to central objects more readily than changes to marginal objects, but they sometimes miss changes to central, attended objects as well. However, even if observers do not report such changes, they may be able to recognize the changed object. In three experiments we explored change detection and recognition memory for several types of changes to central objects in motion pictures. Observers who failed to detect a change still performed at above chance levels on a recognition task in almost all conditions. In addition, observers who detected the change were no more accurate in their recognition than those who did not detect the change. Despite large differences in the detectability of changes across conditions, those observers who missed the change did not vary in their ability to recognize the changing object.

Attention↗
PubMed1987

The representation of uniform motion in vision.

For veridical detection of object motion any moving detecting system must allocate motion appropriately between itself and objects in space. A model for such allocation is developed for simplified situations (points of light in uniform motion in a frontoparallel plane). It is proposed that motion of objects is registered and represented successively at four levels within frames of reference that are defined by the detectors themselves or by their movements. The four levels are referred to as retinocentric, orbitocentric, egocentric, and geocentric. Thus the retinocentric signal is combined with that for eye rotation to give an orbitocentric signal, and the left and right orbitocentric signals are combined to give an egocentric representation. Up to the egocentric level, motion representation is angular rather than three-dimensional. The egocentric signal is combined with signals for head and body movement and for egocentric distance to give a geocentric representation. It is argued that although motion perception is always geocentric, relevant registrations also occur at the three earlier levels. The model is applied to various veridical and nonveridical motion phenomena.

Concept Formation↗
PubMed2005

[Epidemic keratoconjunctivitis. Detecting adenoviruses].

OBJECTIVE: The validity of the 15-min adenovirus assay SAS Adenotest was evaluated compared with virus detection by polymerase chain reaction (PCR) from conjunctival swabs. METHODS: In 75 patients with assumed epidemic keratoconjunctivitis, adenovirus detection from conjunctival swabs was performed by the immunochromatographic assay SAS Adenotest and PCR. RESULTS: In 25 patients adenovirus was detected by PCR, 18 of whom were detected by the SAS Adenotest and 7 of whom were not. No false positive results occurred. Sensitivity was 72% and specificity was 100%. CONCLUSIONS: The results indicate that rapid adenovirus detection with the SAS Adenotest is a useful tool in early epidemic keratoconjunctivitis. An additional PCR should be performed when clinical symptoms persist for 5 days or more.

Adenoviridae↗
PubMed1998

Subtle ultrasonographic anomalies: do they improve the Down syndrome detection rate?

OBJECTIVE: Our purpose was to determine whether the identification of subtle anomalies further improves Down syndrome detection over standard ultrasonographic biometry and the detection of gross morphologic defects. STUDY DESIGN: The screening efficiency of clinodactyly, dilated renal pelvis (> or =4 mm), echogenic bowel, mild ventriculomegaly (> or =10 to 15 mm), and two-vessel cord was determined prospectively in midtrimester fetuses at amniocentesis. The screening efficiency of increased nuchal thickness and shortened long-bone length (standard biometry) and gross morphologic defects was determined for comparison. Multiple backward stepwise regression analysis was used to determine which subtle anomalies significantly correlated with Down syndrome detection rate and whether they increased Down syndrome detection over that with standard biometry and morphologic defects. RESULTS: Although all subtle anomalies except two-vessel cord correlated with the presence of Down syndrome on univariate analysis, only echogenic bowel (Wald chi2 = 15.0211, p = 0.0001) and clinodactyly (Wald chi2 = 9.4273, p = 0.002) persisted in regression analysis of the subtle anomaly group. When either of the above-described anomalies was present, the detection rate for Down syndrome was 28.6%, p < 0.00001. For the combination of standard biometry (either increased nuchal thickness or short humerus) or gross anatomic defect, Down syndrome detection rate was 53.3% (p < 0.00000001). This increased to 63.2% (p < 0.00000001) when subtle anatomic defects (either echogenic bowel or clinodactyly) were included in the definition of an abnormal sonogram. CONCLUSION: Subtle anomalies, of which echogenic bowel and clinodactyly are the most significant, further increase Down syndrome screening efficiency over standard biometry or the finding of gross anatomic defect. Our data appear to support the addition of subtle anomaly findings to ultrasonographic screening for Down syndrome.

Abnormalities, Multiple↗
PubMed2000

On the costs of accessible attitudes: detecting that the attitude object has changed.

The present research examined whether individuals with more accessible attitudes have more difficulty detecting that the attitude object has changed. While being repeatedly exposed to photographs of undergraduates, participants either rehearsed their attitudes toward each photo or performed a control task. They then saw these original photos and computer-generated morphs representing varying degrees of change in an original. Participants in the attitude rehearsal condition required more time to correctly identify morphs that were similar to the original as "different" (Experiment 1) and made more errors in response to such morphs (Experiment 2). Experiment 3 revealed that participants with accessible attitudes perceived relatively less change; they were less likely to view a morph as a photo of a novel person and more likely to view it as a different photo of a person seen before. The costs and benefits of accessible attitudes are discussed.

Adult↗
PubMed1995

Evaluation of the Hybrid Capture human papillomavirus deoxyribonucleic acid detection test.

OBJECTIVE: Our purpose was to evaluate the sensitivity and accuracy of a new, nonradioactive human papillomavirus deoxyribonucleic acid detection method. STUDY DESIGN: Cervical samples from 520 women were assayed for human papillomavirus deoxyribonucleic acid with both the Hybrid Capture test and polymerase chain reaction. RESULTS: Human papillomavirus deoxyribonucleic acid was detected with Hybrid Capture in 106 (42%) of 254 samples from women with no evidence of cervical intraepithelial neoplasia and 211 (79%) of 266 with cervical intraepithelial lesions or cervical cancer. There was a good correlation between Hybrid Capture and polymerase chain reaction. Hybrid Capture correctly identified 92% of samples found to contain a human papillomavirus type with a high or intermediate oncogenic risk with polymerase chain reaction. Although Hybrid Capture can quantify the amount of human papillomavirus deoxyribonucleic acid present in a sample, no correlation was observed between the relative amount of human papillomavirus deoxyribonucleic acid detected with Hybrid Capture and the grade of cervical lesion. CONCLUSION: The Hybrid Capture test is a sensitive and accurate method for identifying human papillomavirus types of high and intermediate oncogenic risk in clinical specimens.

Cervix Uteri↗
PubMedDate not supplied

Cross reactivity between venomous, mildly venomous, and non-venomous snake venoms with the Commonwealth Serum Laboratories Venom Detection Kit.

OBJECTIVE: Studies have noted the relatively common occurrence of positive urine results with the Commonwealth Serum Laboratories Venom Detection Kit (VDK) when testing patients with suspected snakebite who are not envenomed. Possible explanations have been false positive test results or subclinical envenoming. We investigated a third possibility, that there is potential for the venom (or saliva) from mildly venomous and non-venomous snakes to give a positive reading with the VDK. METHODS: Venoms/saliva from three non-venomous and seven mildly venomous snake species were tested in the laboratory with the VDK, along with control venoms from four of the five major snake genera (Brown snake, Tiger snake, Death adder and Black snake). RESULTS: Two of the venom/saliva samples, from Gould's hooded snake (Parasuta gouldii), a mildly venomous snake, and the Black-headed python (Aspidites melanocephalus), a non-venomous snake, caused a positive test for the tiger snake genus. There was also cross-reactivity between black snake venoms and the tiger snake well of the VDK. CONCLUSIONS: This study provides a further possible explanation for 'false positive' VDK results, that is venom/saliva presence or absorption from mildly or non-venomous snakes and cross reactivity with venomous snakes on VDK testing. It has implications for antivenom use should it ever be required for more severe envenoming syndromes from mildly or moderately venomous snakes, and for further research. It reinforces the practice of only using VDK testing in patients who show definite evidence of envenoming.

Animals↗
PubMed2003

Prediction of early pregnancy viability in the absence of an ultrasonically detectable embryo.

OBJECTIVE: To identify clinical, ultrasound and biochemical parameters that may allow prediction of pregnancy viability in women without a detectable embryo on ultrasound examination. METHODS: This was a prospective observational study of pregnant women with an ultrasound finding of a gestational sac measuring < 20 mm mean diameter without a visible embryo. Women's age, menstrual dates, clinical symptoms (pain and bleeding), mean gestational sac diameter and measurements of serum beta-human chorionic gonadotropin and progesterone were recorded in all cases. All women were managed expectantly until the pregnancy viability was established conclusively based on clinical and ultrasound findings. All parameters were tested by univariate analysis and then analyzed in a stepwise procedure to form a logistic regression model for predicting pregnancy viability. RESULTS: One hundred and eighteen (59%) women had a normal intrauterine pregnancy and 82 (41%) had a miscarriage. Stepwise analysis showed that three diagnostic parameters (maternal age, gestational sac diameter and serum progesterone) contributed significantly to the predictive power of the logistic model. With this model, at a cut-off value of 10% probability, the diagnosis of viable pregnancy was made with a sensitivity of 99.2% (95% CI, 95.8-99.97) and specificity of 70.7% (95% CI, 61.3-78.9). CONCLUSION: The use of a logistic regression model allows prediction of pregnancy viability when an embryo cannot be visualized on ultrasound scan.

Abortion, Spontaneous↗
PubMed2004

Prevention of inappropriate therapy in implantable cardioverter-defibrillators: results of a prospective, randomized study of tachyarrhythmia detection algorithms.

OBJECTIVES: The purpose of this randomized study was to investigate the performance of single- and dual-chamber tachyarrhythmia detection algorithms. BACKGROUND: A proposed benefit of dual-chamber implantable cardioverter-defibrillators (ICDs) is improved specificity of tachyarrhythmia detection. METHODS: All ICD candidates received a dual-chamber ICD and were randomized to programmed single- or dual-chamber detection. Of 60 patients (47 male, age 58 +/- 14 years, left ventricular ejection fraction 30%), 29 had single-chamber and 31 had dual-chamber settings. The detection results were corrected for multiple episodes within a patient with the generalized estimating equations method. RESULTS: A total of 653 spontaneous arrhythmia episodes (39 patients) were classified by the investigators; 391 episodes were ventricular tachyarrhythmia (32 patients). All episodes of ventricular tachyarrhythmias were appropriately detected in both settings. In 25 patients, 262 episodes of atrial tachyarrhythmias were recorded. Detection was inappropriate for 109 atrial tachyarrhythmia episodes (42%, 18 patients). Rejection of atrial tachyarrhythmias was not significantly different between both groups (p = 0.55). Episodes of atrial flutter/tachycardia were significantly more misclassified (p = 0.001). Overall, no significant difference in tachyarrhythmia detection (atrial and ventricular) between both settings was demonstrated (p = 0.77). CONCLUSIONS: The applied detection criteria in dual-chamber devices do not offer benefits in the rejection of atrial tachyarrhythmias. Discrimination of atrial tachyarrhythmias with a stable atrioventricular relationship remains a challenge.

Adult↗
PubMed2003

[Reliability and validity of palmar and conjunctival pallor for anemia detection purposes].

OBJECTIVE: To evaluate the reliability and the validity of the use of simple clinical signs as a method of anemia detection. METHODS: The study was carried out in a S o Paulo, Brazil, day-care center, and included 135 children from ages 3 months-6 years. Hemoglobin level results and palmar and conjunctival pallor assessment were used. Children with Hb under 11g/dl were considered as anemic; subjective criteria were used for the assessment of palmar and conjunctival pallor. Kappa statistics were used in order to verify agreement, and, in order to evaluate the technique's validity, sensitivity and specificity levels were calculated. RESULTS: The results show low levels of agreement. There was a greater level of sensitivity to conjunctival pallor than to palmar pallor. Specificity results may be considered as good. CONCLUSIONS: It is still early to recommend the routine use of this technique. However, it could promote substantial savings if perfected.

Anemia↗
PubMed2005

Comparison of virtual cystoscopy, multiplanar reformation, and source CT images with contrast material-filled bladder for detecting lesions.

OBJECTIVE: The objective of our study was to compare the diagnostic accuracy of virtual cystoscopy, multiplanar reformation, and source CT images for lesion detection in the contrast material-filled bladder. SUBJECTS AND METHODS: Two observers independently evaluated 47 patients (28 men and 19 women; mean age +/- SD, 59 +/- 16 years) with virtual cystoscopy, multiplanar reconstruction, and source CT images acquired with contrast material-filled bladder using an MDCT scanner (detector array, 4 x 1.25 mm; beam pitch, 0.75). Agreement between the two observers was evaluated for the three reconstruction methods using kappa statistics. Using the conventional cystoscopic findings as a reference, we compared the results of the three reconstruction techniques both by bladder site and by patient using the McNemar test. RESULTS: The interobserver agreement for the number of positive sites was excellent for virtual cystoscopy (kappa = 0.816), fair for multiplanar reconstruction (kappa = 0.461), and good for source CT images kappa = 0.676). For both observers, the sensitivity for lesion detection by bladder site was significantly greater with virtual cystoscopy (observer 1, 95%; observer 2, 90%) than with multiplanar reconstruction (78% and 60%) and source CT (68% and 65%) images (p < 0.05), whereas the specificity by bladder site and the sensitivity and specificity by patient did not differ with the three methods (p > 0.05). For determining the presence or absence of lesion at each site, virtual cystoscopy was more accurate than multiplanar reconstruction and source CT images for both observers (p < 0.05). CONCLUSION: Virtual cystoscopy is more accurate than multiplanar reconstruction and source CT images for the detection of lesions in the bladder.

Adult↗
PubMed2001

Discriminative whisking in the head-fixed rat: optoelectronic monitoring during tactile detection and discrimination tasks.

We compared whisking movement patterns during acquisition of tactile detection and object discrimination under conditions in which (a) head movements are excluded and (b) exposure to tactile discriminanda is confined to the large, moveable vibrissae (macrovibrissae). We used optoelectronic instrumentation to track the movements of an individual whisker with high spatio-temporal resolution and a testing paradigm, which allowed us to dissociate performance on an "indicator" response (lever pressing) from the rat's "observing" responses (discriminative whisking). We analyzed the relation between discrimination performance and whisking movement patterns in order to clarify the process by which the indicator response comes under the stimulus control of information acquired by the rat's whisking behavior. Whisking patterns over the course of task acquisition differed with task demands. Acquisition of the Detection task was correlated with modulation of only one whisking movement parameter-total number of whisks emitted, and more whisking was seen on trials in which the discriminandum was absent. Discrimination between a sphere and cube differing in size and texture was correlated with a reduction in whisk duration and protraction amplitude and with a shift towards higher whisking frequencies. Our findings confirm previous reports that acquisition of tactile discriminations involves modulation by the animal of both the amount and the type of whisking. In contrast with a previous report (Brecht et al., 1997), they indicate that rats can solve tactile object detection and discrimination tasks (a) using only the large, motile mystacial vibrissae (macrovibrissae) and (b) without engaging in head movements. We conclude that the functional contribution of the macrovibrissae will vary with the nature of the task and the conditions of testing.

Animals↗
PubMed1994

The epidemiology of ovarian carcinoma and the current status of tumor markers to detect disease.

OBJECTIVES: The objectives of this manuscript are to review the epidemiologic characteristics of ovarian cancer and to summarize the current status of tumor markers to detect disease. STUDY DESIGN: A review of the pertinent literature was done. RESULTS: In general, ovarian cancer is most frequent in industrialized countries, with dietary fat and possible use of talc as additive factors. Ovulation appears to increase the risk as does family history, increasing age, infertility, and possibly the use of ovulatory drugs. Pregnancy and the use of oral contraceptives, as well as possibly breast-feeding, lower the risk. Tubal ligation or hysterectomy with ovarian preservation also lowers the risk. The lifetime risk is about 1.4% in the United States, and the risk increases with age. If one first-degree relative has ovarian cancer, the lifetime risk appears to rise to 5%, but this pooled estimate may be affected by self-reporting bias in some studies. CA 125, the most widely used marker, is nonspecific, being elevated in about 80% of cases of ovarian epithelial cancer but also elevated in a number of benign conditions, which reduces its potential effectiveness as a screening tool. CONCLUSIONS: No single cause of ovarian cancer has been uncovered. Overall > 90% of ovarian cancers occur sporadically. Those with the hereditary ovarian cancer syndrome (multiple generations of breast and ovarian cancer) have a 50% risk and an autosomal dominant inheritance, but they constitute < 1% of cases. No ideal tumor marker for ovarian cancer screening is currently available. Further evaluation is needed to see whether the use of multiple tumor markers and/or vaginal ultrasonography might produce an acceptable cost-effective screening model. Current data do not support the utilization of prophylactic oophorectomy in women with one first-degree relative with ovarian cancer as a general strategy to prevent ovarian cancer. It is appropriate strategy for those with hereditary ovarian cancer syndrome.

Biomarkers, Tumor↗
PubMed1999

Breast cancers missed in the prevalent screening round: effect upon the size distribution of incident round detected cancers.

OBJECTIVE: To determine the effect of false negative screens (missed cancers) in the prevalent screening round on the relative size distribution of cancers detected at the first incident screen. SETTING: The Bolton, Bury, and Rochdale breast screening programme. METHODS: One hundred and three breast cancers detected in the first incident round of screening were analysed. The previous (prevalent round) screening films taken between two and four years earlier were subjected to blinded review and classified as either true negatives (no significant abnormality visible) or false negatives (a suspicious abnormality visible at the site of the subsequently detected cancer). The pathological size, type, and grade (where appropriate) of the cancers were recorded. RESULTS: Fifty one of the 103 cancers (49%) detected in the first incident round screen measured < 15 mm in diameter. A total of 32 cases were classified as false negatives. Of these, 12 (38%) measured < 15 mm in diameter. If all the false negative cancers had been detected at the prevalent screen, 39 (55%) of the remaining 71 cancers detected in the first incident round screen would have measured < 15 mm. A relative excess of lobular carcinomas was found among the false negatives. CONCLUSIONS: The findings suggest that although false negative screens in the prevalent round increase the number of cancers available for detection at the first incident round screen, many of these cancers are still < 15 mm in diameter at detection. Cancer detection performance in the prevalent screening round has only a minor influence on the relative proportion of small and large cancers detected at the first incident round screen.

Breast Neoplasms↗