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PubMed2001

Human papillomavirus DNA detection in sperm using polymerase chain reaction.

OBJECTIVE: To detect human papillomavirus (HPV) in semen and find if sperm washing removes HPV DNA. METHODS: Amplification by nested polymerase chain reaction (PCR) was used to detect viral DNA sequences in semen samples from 85 volunteers. Forty-five men had historical or clinical evidence of genital HPV infection (study group) and 40 were healthy, clinically HPV-negative semen donors. RESULTS: We detected HPV DNA in the sperm cells of 24 of 45 subjects (53%) with past or current HPV infections in contrast to three of 40 healthy subjects (8%) (P <.001). Overall, PCR detected HPV in 21 of 32 subjects (66%) with identifiable lesions and six of 53 (11%) without them (P <.001). Swim-up washings of all 27 prewash sperm cells with HPV reduced cellular HPV DNA below detectable levels in only two cases. CONCLUSION: HPV is present in sperm cells from infected and apparently healthy subjects, and sperm washing does not eliminate the risk of HPV transmission to recipients. We suggest that HPV DNA testing should be done on the semen of prospective donors, and those with positive tests should be excluded from donation.

Adult↗

PubMed2003

Electric images of two low resistance objects in weakly electric fish.

Electroreceptive fish detect nearby objects by processing the information contained in the pattern of electric currents through their skin. In weakly electric fish, these currents arise from a self-generated field (the electric organ discharge), depending on the electrical properties of the surrounding medium. The electric image can be defined as the pattern of transepidermal voltage distributed over the receptive surface. To understand electrolocation it is necessary to know how electric image of objects are generated. In pulse mormyrids, the electric organ is localized at the tail, far from the receptors and fires a short biphasic pulse. Consequently, if all the elements in the environment are resistive, the stimulus at every point on the skin has the same waveform. Then, any measure of the amplitude (for example, the peak to peak amplitude) could be the unique parameter of the stimulus at any point of the skin. We have developed a model to calculate the image, corroborating that images are spread over the whole sensory surface and have an opposite center-surround, "Mexican-hat" shape. As a consequence, the images of different objects superimpose. We show theoretically and by simulation that the image of a pair of objects is not the simple addition of the individual images of these objects.

Animals↗

PubMed2000

Anaerobic bacteria and intrahepatic stones: detections of Clostridium sp. and Bacteroides fragilis.

OBJECTIVE: To detect anaerobic bacteria Clostridium sp. and Bacteroides fragilis in intrahepatic stones by molecular genetic method. METHODS: DNA was extracted from 59 stone samples and subjected to polymerase chain reaction (PCR) amplification targeting the 16S rRNA gene of Clostridium sp. and the glutamine synthetase gene of Bacteroides fragilis. Single-strand conformational polymorphism (SSCP) analysis was performed to identify the Clostridium sp. RESULTS: 16S rRNA gene sequences for Clostridium sp. were identified in 49 stones (83%, 49/59). The two most common groups were detected in 19 (41%) and 17 (37%) of the 46 samples using SSPC analysis, and 25/59 (42%) stones were tested positive for Bacteroides fragilis. CONCLUSIONS: Anaerobes such as Clostridium sp. and Bacteroides fragilis present in intrahepatic stones and may play a role in stone formation. PCR is a useful technique to detect fastidious pathogens, which are difficult to culture. SSCP of PCR products is a rapid method in differentiating bacterial species.

Adult↗

PubMed2001

Nested polymerase chain reaction in detection of Plasmodium vivax sporozoites in mosquitoes.

OBJECTIVE: To detect malaria DNA in mosquitoes. METHODS: A nested polymerase chain reaction (nested PCR) procedure which amplifies a 121 bp DNA of a SSUrRNA gene specific to Plasmodium vivax was used. RESULTS: In laboratory-infected mosquitoes, nested PCR could detect as few as 3 sporozoites or 1 infected mosquito mixed in a group of 99 normal ones. Furthermore, no specific 121 bp band was seen with DNA templates from other malaria parasites or negative mosquitoes. CONCLUSION: Sensitivity and specificity obtained indicated an advantage of the nested PCR over DNA probes or direct PCR for the detection of Plasmodium vivax sporozoites in mosquitoes with low-grade parasitic infections.

Animals↗

PubMed2000

[Detecting the level of Actinobacillus actinomycetemcomitans leukotoxin].

OBJECTIVE: To detect the level of Actinobacillus actinomycetemcomitans (Aa) leukotoxin and distinguish the highly and the minimally toxic strains. METHODS: The polymerase chain reaction (PCR) assay was used to detect the difference of the nucleotide sequence of Aa leukotoxic promoter. 68 Aa isolates were examined, including 17 serotype b, 42 serotype c and 9 serotype a strains. The positive control strains were the highly toxic strain JP2 and 7 minimally toxic strains such as ATCC43717; the negative control strains were 12 other species of reference strains. RESULTS: The PCR fragments of JP2 was about 492 bp and that of the other Aa reference strains and 68 clinical isolates were 1,022 bp. PCR products not found in 12 other species. CONCLUSION: All of the 68 clinical isolates were minimally toxic strains.

Adolescent↗

PubMed2002

[Extended-spectrum beta-lactamase detection in Enterobacteriaceae and antibiotic susceptibility analysis].

OBJECTIVE: To detect the extended-spectrum beta-lactamases (ESBLs) in family Enterobacteriaceae and analyze the antibiotic susceptibility of those ESBLs-producing strains. METHODS: ESBLs were determined by the double-disk confirmatory test and 8 antibiotic susceptibilities were tested with the disk disffusion method in those strains producing ESBLs. RESULTS: Forty-seven ESBLs-producing strains comprised of 25 of E. coli, 14 of K. pneumoniae, 5 of E. cloacae, 1 of K. oxytoca, 1 of K. rhinoscleromatis, and 1 of S. liquefaciens. The susceptibility rates of those strains were: 100% for imipenem and meropenem, 89.4% for piperacillin/tazobactam, 72.4% for cefoxitin and 65.9% for cefotetan. CONCLUSION: E. coli and K. pneumoniae are the prime strains producing ESBLs in Enterobacteriaceae. Imipenem and meropenem are the best drugs to deal with those ESBLs-producing strains. Piperacillin/tazobactam is better than cephamycins and other beta-lactama/beta-lactamase inhibitor combination.

Anti-Bacterial Agents↗

PubMed2002

Reactivity to object and spatial novelty is normal in older Ts65Dn mice that model Down syndrome and Alzheimer's disease.

Ts65Dn mice, a model for Down syndrome and Alzheimer's disease, have a spontaneous age-related reduction of cholinergic markers in medial septal neurons, hippocampal abnormalities, and an age-related learning deficit in a task that requires an intact hippocampus. Others have shown that when normal rodents explored an open field with objects, they detected the displacement of some of the familiar objects within the arena (spatial novelty) and the presence of a new object (object novelty); whereas rodents with hippocampal, fornix, or neonatal selective basal forebrain cholinergic lesions were impaired in detecting spatial, but not object, novelty. In this study, both control and Ts65Dn mice responded to both the spatial and object changes. This unexpected finding could have several explanations. One may be related to recent studies that suggest that only rats with neonatal, but not adult, basal forebrain cholinergic 192 IgG-saporin lesions are impaired in reacting to spatial novelty.

Aging↗

PubMed2002

Detection of intrasaccadic displacements and depth rotations of moving objects.

In a display with a stationary and a moving object, subjects saccaded towards one of the objects and had to detect intrasaccadic changes in position or orientation of either the saccade target or the saccade flanker. Compared to performance for stationary objects, displacement detection for translating objects was better and unaffected by saccadic status of the changed object. This pattern proved to be specific to position changes in translating objects and did not generalize to other types of motion (i.e., rotation) or to other types of intrasaccadic changes (i.e., orientation shifts). Superior transsaccadic coding of the position of a translating object was also observed in control experiments with only a single object present on each trial. Possible accounts in terms of selective attention to moving objects and perceptual relevance of object position are pitted against the data, suggesting qualitative differences in the transsaccadic representation of translating and stationary objects.

Depth Perception↗

PubMed1997

Renal blood flow detection with Doppler ultrasonography in patients with hepatic cirrhosis.

BACKGROUND: Hepatorenal syndrome, a well-recognized complication of established liver disease, is characterized by early renal vasoconstriction before clinically recognized renal disease. Renal vasoconstriction causes increased renal vascular resistance, which can be detected noninvasively by Doppler ultrasonography. OBJECTIVE: To detect early renal hemodynamic changes in patients with hepatic cirrhosis who had clinically normal renal functions. PATIENTS: Twenty patients with hepatic cirrhosis and ascites, 11 patients with hepatic cirrhosis without ascites, and 23 healthy control subjects. All cirrhotic patients had normal serum urea nitrogen and creatinine values. MAIN OUTCOME MEASURES: Peak systolic, peak diastolic, and mean flow velocities; pulsatile index; resistive index; and peak systolic velocity/peak diastolic velocity ratio as measured by renal Doppler ultrasonography. RESULTS: Peak diastolic flow velocity was significantly lower in cirrhotic patients with ascites than in cirrhotic patients without ascites and control subjects (P < .02 and P < .004, respectively), but the peak systolic flow velocity/peak diastolic flow velocity ratio (P < .007 and P < .001, respectively), pulsatile index (P < .007 and P < .001, respectively), and resistive index (P < .007 and P < .001, respectively) were significantly higher in cirrhotic patients with ascites than in cirrhotic patients without ascites and controls. CONCLUSION: Renal Doppler ultrasonography can noninvasively identify a subgroup of nonazotemic patients with hepatic cirrhosis who are at high risk for subsequent development of renal dysfunction and hepatorenal syndrome.

Adult↗

PubMed2002

Detection of low-contrast objects: experimental comparison of single- and multi-detector row CT with a phantom.

PURPOSE: To compare single-detector row computed tomography (CT) and multi-detector row CT by using an experimental phantom containing a contrast-detail modulus for detection of low-contrast structures to optimize acquisition protocols. MATERIALS AND METHODS: The parameters milliampere seconds, reconstructed section thickness, and elementary collimation for multi-detector CT were varied for two pitches with single- and multi-detector CT. For objective assessment of image quality, contrast-to-noise ratio (CNR) was calculated for an 8-HU low-contrast 15-mm-diameter object. Subjective assessment of image quality was performed by means of visual detection of low-contrast objects of various sizes by four independent observers. For each acquisition protocol, the effective doses required to obtain the CNR thresholds allowing 100% detection of 5-, 7-, and 9-mm-diameter objects were compared at single- and multi-detector CT at comparable section sensitivity profile with analysis of variance. RESULTS: Significant correlation was found between CNR measurements and subjective object detection (r = 0.95, P <.05). CNRs of 1.0, 0.8, and 0.6 were required to detect 100% of the 5-, 7-, and 9-mm-diameter objects, respectively. For reconstructed section thickness of 5-10 mm, comparable x-ray doses were required with single- and multi-detector CT to detect objects. For reconstructed sections thinner than 5 mm, single- and multi-detector CT allowed detection of only the 7- and 9-mm-thick objects, but a higher x-ray dose was required for multi- than for single-detector CT (P <.05). CONCLUSION: Multi-detector CT is less effective than single-detector CT in detection of small low-contrast objects if sections thinner than 5 mm are used. Results for single- and multi-detector CT were similar for sections 5 mm or thicker.

Analysis of Variance↗

PubMed1995

Objective versus human observer detection of 40-Hz auditory-evoked potentials.

Magnitude-squared coherence (MSC) was used to detect 40-Hz auditory-evoked potentials (AEPs) in a two-alternative forced-choice experiment. MSC performance was found to be better than that of ten human observers. Experienced observers did not perform better than naive observers. In a "yes-no" experiment, observers demonstrated large differences in criterion, with false-positive rates of 2%-20%. Observers also performed better when AEPs were presented in a 50-ms window (two response cycles) than when presented in a 205-ms window (eight response cycles), although total test time was the same; MSC performed equally well in both cases. MSC provides a useful and objective adjunct to visual detection of 40-Hz AEPs.

Adult↗

PubMed1994

Detection of one versus two objects in structure from motion.

The ability of subjects to detect whether a structure-from-motion display depicts one or two rigid objects was examined in the presence or the absence of noise points. Each object was composed of a set of points chosen randomly within the volume of a sphere. The objects rotated rigidly about different axes passing through the center of the sphere. For displays without noise points, detection increased with larger angles between the rotation axes and with more points in each object. For displays in which noise points were present, detection was above chance but, in general, worse than that for displays without noise points. The implications of these results for image segmentation in complex motion patterns is discussed.

Form Perception↗

PubMed2002

Agricultural machinery safety alert system using ultrasonic sensors.

This article introduces a conceptual safety alert system using ultrasonic sensors. The safety alert system was designed to detect moving objects in the vicinity of agricultural machinery. This system uses two ultrasonic sensors to detect the distances between the sensors and the moving object and a position detection algorithm to determine the moving object's position relative to the machinery. A stationary test bench was built to prove the concept of the safety sensing system. Validation tests in an outdoor environment indicated that the conceptual safety alert system was capable of detecting the position of a moving object in the vicinity of agricultural machinery in real time, and generating a timely warning signal to raise the attention of the operator for ensuring safe operations. This result proved that the conceptual system has tremendous potential for agricultural machinery applications.

Accidents, Occupational↗

PubMed1998

Evaluation of posturography in the detection of malingering subjects.

OBJECTIVE: This study aimed to test the performance of proposed methods for detecting malingering subjects on computerized dynamic posturography using one subject group in three situations (normal, malingering, vestibular weakness). STUDY DESIGN: The study design was a prospective, blinded study. SETTING: The study was conducted at a university hospital. PATIENTS: Volunteer subjects aged 20-59 years of age participated. INTERVENTIONS: Computerized dynamic posturography was performed under three situations: best effort, faking vestibular weakness, and transient induced vestibular weakness with bilateral simultaneous caloric irrigation. MAIN OUTCOME MEASURES: Measured was identification of situation (normal, malingering, induced vestibular weakness) by each of three detection methods: blinded clinical scoring, a set of formulae, and a set of variables (the latter two methods proposed previously by other investigators). RESULTS: Each method performed well. In three-way discrimination, the formulae and clinical scoring each correctly identified approximately 75% of trials. In two-way discrimination (malingering vs. induced vestibular weakness), the best combination of variables slightly outperformed clinical scoring (0.93 vs. 0.88 ROC [receiver operating characteristic] curve area). CONCLUSIONS: Computerized dynamic posturography can distinguish malingering in normal subjects from trials performed with best effort or after binaural simultaneous caloric irrigation. The accuracy of blinded clinical scoring was comparable to that of two objective detection methods.

Adult↗

PubMed2005

Polar body biopsy and aneuploidy testing by simultaneous detection of six chromosomes.

OBJECTIVES: To simultaneously detect six chromosomes in a single round of fluorescence in situ hybridization (FISH) during polar body diagnosis and aneuploidy testing in human in vitro fertilization (IVF) treatment. METHODS: A commercially available five-color FISH probe was modified by an additional chromosome probe. This kit was first tested on lymphocyte spreads and then used for polar body diagnosis (PBD) in patients with advanced maternal age and repeated implantation failure. The outcome of IVF treatment was compared with a control group. RESULTS: All six chromosomes could be simultaneously detected and easily distinguished by FISH analysis. PBD and aneuploidy testing were performed in 75 treatment cycles and compared with 126 controls. The biochemical pregnancy rate was significantly higher in the PBD group (37.1% vs 22.9%, p < 0.05) and a trend was observed for higher clinical pregnancy and implantation rates (24.22% and 14.4% vs 18.62% and 10.8%, respectively) and lower abortion rates (20% vs 31.8%) following PBD. CONCLUSIONS: The simultaneous detection of six chromosomes in a single FISH round is possible and can be applied to PBD. This approach may present another step towards increasing the number of chromosomes for aneuploidy testing.

Adult↗

PubMed2005

Prospective audit of a one-centre combined nuchal translucency and triple test programme for the detection of trisomy 21.

OBJECTIVES: To determine detection and false-positive rates for trisomy 21 using two-stage combined nuchal translucency (NT) and triple testing, whilst disclosing abnormal nuchal measurements at the scan. METHODS: A prospective audit in a UK women's hospital, of 3188 women with singleton pregnancies, requesting screening for trisomy 21. Median age was 37 years (range 19-46). Women were offered NT screening at 11 to 14 weeks. Those with NT > or =3 mm were offered chorionic villus sampling. Those declining CVS, and those with NT <3 mm, were offered early triple tests. Women with a term combined risk of trisomy 21 > or = 1:250, based on age, NT, and triple test results were offered amniocentesis. RESULTS: Using a 3-mm NT 'cut-off' identified 16/25 cases of trisomy 21 (64%; 95% CI 38.8, 78.9). Of 2725 women who had a combined nuchal plus triple test assessment, 79 (2.6%) had a > or = 1:250 term risk of trisomy 21. Forty (1.3%) had amniocentesis identifying 6/9 remaining cases (67%:95% CI:27.9, 92.5). Overall, the detection rate was 88% (95% CI:68.8, 97.5) for a 4.8% FPR. For the screened population, to achieve an 88% detection rate using the triple test alone, the predicted FPR would be 20%. Conversely, for an FPR of 4.8% using the triple test alone, the detection rate would be only 60%. CONCLUSION: In a high-risk group, the combination of NT with triple test offers detection of trisomy 21 at least equivalent to either test, while allowing disclosure of an abnormal NT at the scan and reducing the FPR. Importantly, the FPR is less than 5%, considerably lower than expected for triple test alone for this population.

Adult↗

PubMed1984

Figure-ground segregation by motion contrast and by luminance contrast.

Some naturally camouflaged objects are invisible unless they move; their boundaries are then defined by motion contrast between object and background. We compared the visual detection of such camouflaged objects with the detection of objects whose boundaries were defined by luminance contrast. The summation field area is 0.16 deg2 , and the summation time constant is 750 msec for parafoveally viewed objects whose boundaries are defined by motion contrast; these values are, respectively, about 5 and 12 times larger than the corresponding values for objects defined by luminance contrast. The log detection threshold is proportional to the eccentricity for a camouflaged object of constant area. The effect of eccentricity on threshold is less for large objects than for small objects. The log summation field diameter for detecting camouflaged objects is roughly proportional to the eccentricity, increasing to about 20 deg at 32-deg eccentricity. In contrast to the 100:1 increase of summation area for detecting camouflaged objects, the temporal summation time constant changes by only 40% between eccentricities of 0 and 16 deg.

Humans↗

PubMed2006

Automatic estimation of detector radial position for contoured SPECT acquisition using CT images on a SPECT/CT system.

An algorithm was developed to estimate noncircular orbit (NCO) single-photon emission computed tomography (SPECT) detector radius on a SPECT/CT imaging system using the CT images, for incorporation into collimator resolution modeling for iterative SPECT reconstruction. Simulated male abdominal (arms up), male head and neck (arms down) and female chest (arms down) anthropomorphic phantom, and ten patient, medium-energy SPECT/CT scans were acquired on a hybrid imaging system. The algorithm simulated inward SPECT detector radial motion and object contour detection at each projection angle, employing the calculated average CT image and a fixed Hounsfield unit (HU) threshold. Calculated radii were compared to the observed true radii, and optimal CT threshold values, corresponding to patient bed and clothing surfaces, were found to be between -970 and -950 HU. The algorithm was constrained by the 45 cm CT field-of-view (FOV), which limited the detected radii to < or = 22.5 cm and led to occasional radius underestimation in the case of object truncation by CT. Two methods incorporating the algorithm were implemented: physical model (PM) and best fit (BF). The PM method computed an offset that produced maximum overlap of calculated and true radii for the phantom scans, and applied that offset as a calculated-to-true radius transformation. For the BF method, the calculated-to-true radius transformation was based upon a linear regression between calculated and true radii. For the PM method, a fixed offset of +2.75 cm provided maximum calculated-to-true radius overlap for the phantom study, which accounted for the camera system's object contour detect sensor surface-to-detector face distance. For the BF method, a linear regression of true versus calculated radius from a reference patient scan was used as a calculated-to-true radius transform. Both methods were applied to ten patient scans. For -970 and -950 HU thresholds, the combined overall average root-mean-square (rms) error in radial position for eight patient scans without truncation were 3.37 cm (12.9%) for PM and 1.99 cm (8.6%) for BF, indicating BF is superior to PM in the absence of truncation. For two patient scans with truncation, the rms error was 3.24 cm (12.2%) for PM and 4.10 cm (18.2%) for BF. The slightly better performance of PM in the case of truncation is anomalous, due to FOV edge truncation artifacts in the CT reconstruction, and thus is suspect. The calculated NCO contour for a patient SPECT/CT scan was used with an iterative reconstruction algorithm that incorporated compensation for system resolution. The resulting image was qualitatively superior to the image obtained by reconstructing the data using the fixed radius stored by the scanner. The result was also superior to the image reconstructed using the iterative algorithm provided with the system, which does not incorporate resolution modeling. These results suggest that, under conditions of no or only mild lateral truncation of the CT scan, the algorithm is capable of providing radius estimates suitable for iterative SPECT reconstruction collimator geometric resolution modeling.

Algorithms↗