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PubMed1981

Visual form perception and the spatial phase transfer function.

The quality of many imaging devices can be characterized, within certain constraints, by means of the modulation transfer function (MTF) and the phase transfer function (PTF). In many cases, it is possible to estimate, qualitatively, the effect of the MTF on the appearance of objects, and much progress has been made in making quantitative predictions of the detectability of objects and features within objects. This is not the case, however, for the PTF, and its influence is often neglected, even though nonideal PTF's obviously may degrade image quality. Experiments are described that attempt to assess the significance of the PTF for human visual performance. The effects of various PTF's were simulated by means of a technique that maintained the modulation of the spatial-frequency components closely constant. The visual detectability of such phase changes was measured by a discrimination method, and phase threshold levels were evaluated. Simple linear patterns provided the targets for all measurements, although some images are shown that illustrate qualitatively the phase-shift results on real two-dimensional targets. The work enables an assessment to be made of the effects of phase changes produced by various imaging systems.

Form Perception↗
PubMed1998

Detection rate of the cervical gland area during pregnancy by transvaginal sonography in the assessment of cervical maturation.

OBJECTIVES: To detect the cervical gland area during normal pregnancy, and to determine its detection rate and relationship with cervical maturation. DESIGN: This was a mixed longitudinal and cross-sectional sonographic study involving a total of 514 transvaginal scans performed for detection of cervical gland area and measurement of cervical length in 260 normal singleton pregnancies at 16-41 weeks of gestation. The conventional cervical maturation index was measured simultaneously by digital examination. RESULTS: The detection rate of cervical gland area remained practically constant until the 31st week of pregnancy, but significantly decreased thereafter. Highly significant correlations were noted between the detection rate of cervical gland area and cervical length, cervical gland area and cervical maturation index, and cervical length and cervical maturation index. CONCLUSIONS: This study showed for the first time that cervical gland area can be detected sonographically and that its absence might be a predictor of preterm labor.

Adolescent↗
PubMed1998

Detection of hepatitis C virus RNA sequences in hepatic portal cholangiocarcinoma tissue by reverse transcription polymerase chain reaction.

OBJECTIVE: To detect hepatitis C virus (HCV) RNA sequences in the hepatic portal cholangiocarcinoma tissues and their relationship. METHODS: RNA was extracted from paraffin-embedded cholangiocarcinoma tissues of 6 patients by guanidinium method, subjected to reverse transcription and then amplified by double PCR technique using nested primers from the highly conserved 5' noncoding region of HCV genome. RESULTS: HCV RNA of 5' NT sequences was found in the hepatic portal cholangiocarcinoma tissues of 5 out of 6 (83%) patients. CONCLUSIONS: HCV RNA sequences present with high infectious rate in cholangiocarcinoma, and reverse transcription polymerase chain reaction (RT-PCR) assay using primers derived from 5' NT region of HCV sequence is most useful in detecting HCV infection. The development of cholangiocarcinoma awaits further studies.

Adenocarcinoma↗
PubMed2000

[Detection of K-ras gene mutations in DNA extracted from the plasma of patients with pancreatic cancer].

OBJECTIVES: To detect mutations of the K-ras codon 12 in DNA extracted from the plasma of patients with pancreatic cancer, and to explore the possibility of using this method in early diagnosis of pancreatic cancer. METHODS: Plasma DNA was isolated from the blood of 22 patients with pancreatic cancer and from 20 normal controls. K-ras codon 12 mutations were detected by mutant enriched polymerase chain reaction-restriction fragment length polymorphism technique and subsequent product sequencing. The relation of K-ras mutations in plasma to clinical features in pancreatic cancer patients was analyzed. RESULTS: Seventeen (77.3%) of 22 patients with pancreatic cancer had a codon 12 K-ras mutation in their plasma DNA. In two patients, the PCR products were sequenced and the mutations were confirmed. The occurrence of K-ras mutations in the plasma DNA was not related to tumor location, tumor size, and TNM stage. No K-ras mutation was detected in the plasma specimen of any of the normal controls. CONCLUSIONS: K-ras mutations are frequently found in the plasma DNA of patients with pancreatic cancer. Analysis of K-ras mutation in the plasma DNA may be useful in the early detection of pancreatic cancer.

Adult↗
PubMed2005

[Detection of EWS-WT1 fusion transcripts in paraffin-embedded tissues for desmoplastic small round cell tumor].

OBJECTIVE: To detect the EWS-WT1 chimeric mRNA in desmoplastic small round cell tumor (DSRCT) and its clinicopathological significance. METHODS: Formalin fixed, paraffin-embedded tumor specimens from 4 examples of this entity were studied by reverse transcriptase polymerase chain reaction to detect the EWS-WT1 fusion transcripts resulting from the chromosomal translocation t(11;22)(p13;q12). The following tumor specimens were included as controls: 2 Ewing's sarcomas/primitive neuroectodermal tumors (PNET/ES), 2 alveolar rhabdomyosarcomas, and 2 lymphomas. RESULTS: EWS-WT1 fusion transcripts were detected in 3 of 4 desmoplastic small round cell tumors but not in any other tumor types studied as controls. CONCLUSION: The analysis of the EWS-WT1 fusion transcript which was performed on formalin-fixed, paraffin-embedded tissues is a sensitive and specific method in the diagnosis and differential diagnosis of DSRCT.

Abdominal Neoplasms↗
PubMed2006

[Rapid detection of most frequent chromosomal aneuploidies by the multiplex QF PCR method in the first trimester of pregnancy].

OBJECTIVE: Rapid detection of most frequent aneuploidies by the multiplex QF PCR method in non-cultured samples of chorial tissue. Summarized results of QF PCR method applied in the management of care of pregnant women in the first trimester of pregnancy. TYPE OF STUDY: An original contribution. SETTING: Institute of Medical Genetics and Fetal Medicine, Faculty Hospital and Medical Faculty, Palacky University Olomouc. METHODS: The samples of chorial tissue were obtained from 101 pregnant women. Non-cultured samples were processed by the multiplex QF PCR method. STR loci of chromosomes 13, 18, 21 and X and Y were analyzed. These markers were amplified in two separate multiplex PCR reactions under the same conditions and subjected to fragmentation analysis in capillary electrophoresis. RESULTS: All 101 analyzed samples of chorial tissue were successfully amplified. In this group, 16 pathologies of the fetuses were detected by the multiplex QF PCR method. Triploidy was detected in two cases, trisomy of chromosome 21--Down syndrome was found in seven cases, and trisomy of chromosome 18--Edwards syndrome was found in six cases and monosomy of gonosome X--the Turner' s syndrome was revealed once. CONCLUSIONS: The multiplex QF PCR method is an indispensable part of the screening of the first trimester and provides a rapidly available and reliable result in the examined patients.

Aneuploidy↗
PubMed2006

[Detection of P-4 and GP-46 expression in Leishmania amazonensis amastigotes and promastigotes by RT-PCR].

OBJECTIVE: To detect the expression level of stage-specific genes in Leishmania promastigotes and amastigotes. METHODS: Total RNAs were isolated from Leishmania amazonensis stationary promastigotes and three sources of amastigotes: freshly obtained from mouse skin lesions, infected J774.G8 macrophages, and transformed from the cultured promastigotes. mRNAs were conversely transcribed into cDNA with SuperScripII reverse transcriptase and oligo dT primers. The polymerase chain reaction (PCR) was used to amplify the specific fragments of amastigote-specific nuclease (P-4) and promastigote-specific membrane glycoprotein (GP-46). PCR products were analyzed in 1.5% agarose gel. RESULTS: A P-4-specific band (273 bp) was observed in all three types of amastigotes with similar density, but it was almost undetectable in promastigotes. In contract, a GP-46-specific band (325 bp) was expressed at a higher level in promastigotes than in all three types of amastigotes. CONCLUSION: Promastigote-derived amastigotes express high level of P-4-specific gene and can be used as a source of amastigotes for biochemical and immunological studies.

Animals↗
PubMed1993

Specific amplification of Aspergillus fumigatus DNA by polymerase chain reaction.

We have developed a specific and sensitive method to detect the human pathogen Aspergillus fumigatus by polymerase chain reaction (PCR) with an objective of detecting the organism in peripheral blood and urine which can be obtained by non-invasive procedures. A pair of oligonucleotide primers for PCR were designed based on the published partial protein sequences of an 18 KD IgE-binding protein of A. fumigatus Asp f1 and the ribotoxins mitogillin and restrictocin of A. restrictus, and alpha-sarcin of A. giganteus. The primers were specific in amplifying an expected 315 bp region of the homologous genes in A. fumigatus and A. restrictus but not in A. giganteus. Also, there was no amplification of human DNA or DNA of A. flavus, A. niger, A. fischeri, Penicillium sp., Candida albicans and Pneumocystis carinii. The sensitivity of the PCR detection of A. fumigatus DNA is about 20 pg on an ethidium bromide gel and 0.6 pg by Southern analysis using a 32P-labelled internal oligonucleotide. In preliminary analysis of 13 urine specimens of patients suspected of invasive aspergillosis (IA), two were PCR positive, one of whom died of IA with brain lesion. Further analyses of both urine and blood specimens of IA are in progress to determine the comparative utility of PCR over the conventional antigen tests.

Aspergillus↗
PubMed1995

Signal detection in averaged evoked potentials: Monte Carlo comparison of the sensitivity of different methods.

Many clinical and research applications rely on detecting evoked potential (EP) signal or EP differences between conditions. Statistical methods for objective signal detection should be sensitive to the presence of signal, but must provide the user strict control on tolerated false alarm rate. The respective sensitivities of 6 signal detection methods were compared through several Monte Carlo simulations involving 2 autocorrelation structures, 5% and 1% significance levels, 8, 10 or 12 replications per study, and increasing signal to noise ratio. The signal detection methods compared were: (1) the Record Orthogonality Test by Permutations (ROT-p), a variant of the Residual Orthogonality Test (Achim et al., 1988), that provides an unbiased estimate of the energy of the signal present in the averaged data, (2) the Tsum2 permutation test of Karniski et al. (1994), (3) a Principal Component Analysis method (PC1) consisting of a t test on the weights of the first principal component, (4) multiple t tests on amplitudes with empirical adjustment for global false alarm rate, and (5-6) the test of Guthrie and Buchwald (1991) on length of consecutive t tests significant at P < 0.05 or 0.01 per-test. The first 3 methods did not exceed their nominal false alarm rate and clearly outperformed the last 3, with the ROT-p method being significantly more sensitive than all others under almost all conditions.

Electrophysiology↗
PubMed2002

Amyopathic dermatomyositis: retrospective review of 37 cases.

Criteria for diagnosis of amyopathic dermatomyositis vary, and the prognosis is not clear. Our purpose was to investigate prognosis regarding progression to myositis and associated malignancy. We reviewed the medical records of patients with dermatomyositis evaluated at our institution from 1976 to 1994. Of 746 patients with dermatomyositis, 37 (5%) with the amyopathic subtype were divided into 3 groups: group 1 (73%), no subjective or objective evidence of myopathy; group 2 (13%), no subjective muscle weakness but abnormalities detected by objective tests; group 3 (13%), subjective muscle weakness but no objective evidence of myopathy. Follow-up was conducted by means of a mailed questionnaire. For 25 patients, follow-up of 1 to 17 years after diagnosis showed muscle weakness in 2 patients in group 1 within 5 years after diagnosis. Five patients (13%) had associated malignancies. Of 7 (19%) patients with disease onset before the age of 18 years, none had progression to myopathy. Although it presents with cutaneous lesions indistinguishable from those of classic dermatomyositis, amyopathic dermatomyositis is a distinct entity. In most patients, amyopathic dermatomyositis does not progress to myopathy. Prognosis appears favorable, but malignancy may develop.

Adolescent↗
PubMed2003

Remote sensing of penetrable objects buried beneath two-dimensional random rough surfaces by use of the Mueller matrix elements.

The modified Mueller matrix elements for electromagnetic scattering from penetrable objects buried under two-dimensional random rough surfaces are investigated. This matrix relates the incident to the scattered waves, and it contains different combinations of the fully polarimetric scattering matrix elements. The statistical average of each Mueller matrix element is computed on the basis of the Monte Carlo simulations by exploiting the speed of the three-dimensional steepest-descent fast multipole method. The numerical results clearly show that relying only on the co-polarized or the cross-polarized intensities or both (i.e., vv, hh, vh, and hv) is not sufficient for sensing the buried objects. However, examining all 16 Mueller matrix elements significantly increases the possibility of detecting these objects. This technique can be used in remote sensing of scatterers buried beneath the rough ground.

Journal Article↗
PubMed1995

Determination of normal ear temperature with an infrared emission detection thermometer.

STUDY OBJECTIVE: To determine normal body temperature with an infrared emission detection ear thermometer. DESIGN: Cross-sectional convenience sample. SETTING: Four acute and long-term health care facilities. PARTICIPANTS: Subjects who denied recent potentially febrile illness and ingestion of medications affecting normal body temperature. RESULTS: Two thousand four hundred forty-seven subjects aged 12 hours to 103 years were enrolled. Ear temperatures were normally distributed for each of eight age groups. There were differences in mean temperature among different age groups (P < .001, by ANOVA) and a striking cutoff at adolescence; the mean temperature for children aged 3 days to 10 years was 36.78 +/- 0.47 degrees C, as compared to 36.51 +/- 0.46 degrees C for subjects 11 years and older (P < .001, by t test). Temperatures were higher in female subjects and showed the characteristic diurnal variation of normal body temperature in five subjects studied longitudinally. The reproducibility of the ear thermometer was better than that of a commonly used electronic thermometer at the oral and axillary sites. CONCLUSION: The infrared emission detection ear thermometer is an accurate means of assessing normal body temperature without using corrective offsets to estimate temperature at other body sites. On the basis of these data, the 95th percentile for infrared emission detection temperature in children younger than 11 years old was 37.6 degrees C. The 99th percentile was 37.9 degrees C for children younger than 11 years old and 37.6 degrees C for people 11 years or older. Because only 1% of normal people have an infrared emission detection temperature higher than these values, these may represent appropriate cutoffs for fever screening using this device.

Adolescent↗
PubMed2002

Selective use of ultrasonography for the detection of pneumoperitoneum.

OBJECTIVE: Whether ultrasonography is superior to plain radiography for the detection of pneumoperitoneum is unknown. The goal of this study was to determine the value of ultrasonography for the detection of pneumoperitoneum. METHODS: One hundred thirty-two patients with suspected hollow-organ perforation were prospectively selected for study. All 132 patients received ultrasonography, upright chest radiography, and left lateral decubitus abdominal radiography examinations. The diagnostic accuracies of chest and abdominal radiographs for the detection of pneumoperitoneum were compared with corresponding values from ultrasonography. RESULTS: Of the 125 patients who underwent laparotomy, 121 patients had hollow-organ perforation, three patients had perforated appendicitis, and one patient had acute cholecystitis. For the diagnosis of pneumoperitoneum, ultrasonography demonstrated a sensitivity of 93%, a specificity of 64%, a positive predictive value of 97%, a negative predictive value of 44%, and an accuracy of 90%. Plain radiography revealed a sensitivity of 79%, a specificity of 64%, a positive predictive value of 96%, a negative predictive value of 21%, and an accuracy of 77%. CONCLUSIONS: Ultrasonography is a more sensitive diagnosing modality than plain radiography for the diagnosis of pneumoperitoneum. The authors suggest that ultrasonography was a useful diagnostic modality when plain radiographs failed to reveal pneumoperitoneum among patients with suspected hollow-organ perforation.

Adolescent↗
PubMed2006

Combination analysis of a whole lymph node by one-step nucleic acid amplification and histology for intraoperative detection of micrometastasis.

OBJECTIVE: The aim was to develop a more efficient molecular detection system than histological examination (HE) for lymph node (LN) metastasis. METHODS: Cytokeratin (CK) 19 mRNA copy numbers of 5 colon carcinoma cell lines (Lovo, DLD1, WiDr, Colo201 and Colo320) were calculated and compared by one-step nucleic acid amplification (OSNA) and conventional real-time reverse-transcription polymerase chain reaction (RT-PCR). Then, 91 LN submitted for HE from 6 patients with advanced colorectal adenocarcinoma and 64 LN submitted for frozen diagnosis from 47 patients with different malignancies were examined by OSNA and HE. RESULTS: CK19 mRNA copy numbers of all but Colo320 cells detected by OSNA were within double of those detected by RT-PCR. The least cell count of Lovo cells detected at one reaction (2 microl) by OSNA was calculated as 0.8 cells. Carcinoma metastasis showing either HE+ or OSNA+ was detected in 7.9% of the LN from advanced colorectal adenocarcinomas and in 30.0% of the LN for frozen diagnosis from different malignancies; HE-/OSNA+ metastasis was detected in 4.8 and 4.0%, respectively. OSNA analysis of 1 LN could be completed within 40 min. CONCLUSION: A combined analysis of LN by HE and OSNA could increase the sensitivity for detecting micrometastasis during surgery.

Adenocarcinoma↗
PubMedDate not supplied

Lung nodule detection on chest CT: evaluation of a computer-aided detection (CAD) system.

OBJECTIVE: To evaluate the capacity of a computer-aided detection (CAD) system to detect lung nodules in clinical chest CT. MATERIALS AND METHODS: A total of 210 consecutive clinical chest CT scans and their reports were reviewed by two chest radiologists and 70 were selected (33 without nodules and 37 with 1-6 nodules, 4-15.4 mm in diameter). The CAD system (ImageChecker CT LN-1000) developed by R2 Technology, Inc. (Sunnyvale, CA) was used. Its algorithm was designed to detect nodules with a diameter of 4-20 mm. The two chest radiologists working with the CAD system detected a total of 78 nodules. These 78 nodules form the database for this study. Four independent observers interpreted the studies with and without the CAD system. RESULTS: The detection rates of the four independent observers without CAD were 81% (63/78), 85% (66/78), 83% (65/78), and 83% (65/78), respectively. With CAD their rates were 87% (68/78), 85% (66/78), 86% (67/78), and 85% (66/78), respectively. The differences between these two sets of detection rates did not reach statistical significance. In addition, CAD detected eight nodules that were not mentioned in the original clinical radiology reports. The CAD system produced 1.56 false-positive nodules per CT study. The four test observers had 0, 0.1, 0.17, and 0.26 false-positive results per study without CAD and 0.07, 0.2, 0.23, and 0.39 with CAD, respectively. CONCLUSION: The CAD system can assist radiologists in detecting pulmonary nodules in chest CT, but with a potential increase in their false positive rates. Technological improvements to the system could increase the sensitivity and specificity for the detection of pulmonary nodules and reduce these false-positive results.

Diagnosis, Computer-Assisted↗
PubMed2006

[Detection of a previously unrecognized type 2 diabetes using a risk questionnaire. Efficiency for general population screening].

BACKGROUND AND OBJECTIVE: The detection of unknown cases of diabetes mellitus is of great medical and public health interest. In the present study a stepwise screening procedure was used to examine the effectiveness of a diabetes-risk questionnaire at a population level. PATIENTS AND METHODS: 58,254 insured persons (34,179 men and 24,075 women (55 years and older) enrolled in the Health Insurance "Techniker Krankenkasse" of Thuringia and the Duesseldorf area were contacted per mail to participate. 21,218 returned the questionnaire. They were contacted again and encouraged to participate in a medical check-up for early detection of diabetes. RESULTS: Data of 4,314 individuals (20.3%) who participated in the medical check-up were analysed. Their fasting blood glucose was measured (FBG, n=3,888) and, if necessary, they underwent an additional oral glucose tolerance test (OGTT, n=2,048). In 192 cases (4.5%) the general practitioner (GP) diagnosed manifest diabetes mellitus. In an additional 393 patients (9.1%) an impaired glucose tolerance was found. Analysis of documented blood glucose measurements suggested a manifest diabetes mellitus in 3.5% (by OGTT) and 10.3% (by FBG), as well as an impaired glucose tolerance in 16.1% (by OGTT) and 36.6% (by FBG). CONCLUSIONS: These results demonstrate good effectiveness of the screening procedure among the participants of a medical check-up programme for early detection of diabetes mellitus and its precursors. However, the effectiveness of population-based diabetes screening with only a mailing of a risk questionnaire was unsatisfactory.

Aged↗
PubMed2004

Detection and assay of beta-lactamases in clinical and non-clinical strains of Yersinia enterocolitica biovar 1A.

OBJECTIVES: To detect beta-lactamases (A & B) and extended-spectrum beta-lactamases (ESBLs) in clinical and non-clinical isolates of Yersinia enterocolitica biovar 1A, and to determine their activity in the presence of specific lactamase inhibitors. METHODS: The presence of beta-lactamases and ESBLs was detected by disc diffusion in 219 (36 clinical, 183 non-clinical) isolates. beta-Lactamase activity was assayed spectrophotometrically in all 36 clinical and 10 representative non-clinical isolates using nitrocefin as the substrate. Inhibition of beta-lactamases was studied by clavulanic acid, aztreonam and cloxacillin. RESULTS: Of the 219 isolates, all except two non-clinical isolates indicated the presence of beta-lactamase A (Bla-A) based on the smaller (2-8 mm) radius of the inhibition zone around the ticarcillin disc. Synergy between ticarcillin and co-amoxiclav discs was, however, observed in only 34% of isolates of non-clinical origin. beta-Lactamase B (Bla-B) was found to be consistently positive among all the clinical and non-clinical isolates, as indicated by its characteristic appearance of flattening of the zone of inhibition around the cefotaxime disc adjacent to an imipenem disc. Bla-B was induced more strongly in clinical than in non-clinical isolates. Inhibition of enzyme A by clavulanic acid, aztreonam and cloxacillin was found to be similar, whereas enzyme B was inhibited more strongly by aztreonam and cloxacillin. None of the isolates showed the unequivocal presence of ESBL. CONCLUSION: This is the first report on beta-lactamases of Yersinia enterocolitica biovar 1A from Asia. Y. enterocolitica biovar 1A expressed both Bla-A and Bla-B. Heterogeneity was, however, discerned in the expression of Bla-A and by induction of Bla-B among clinical and non-clinical isolates of Y. enterocolitica biovar 1A.

Animals↗
PubMed2004

Detecting structural changes in early experimental osteoarthritis of tibial cartilage by microscopic magnetic resonance imaging and polarised light microscopy.

OBJECTIVES: To detect changes in the collagen fibril network in articular cartilage in a canine experimental model of early osteoarthritis (OA) using microscopic magnetic resonance imaging (microMRI) and polarised light microscopy (PLM). METHODS: Eighteen specimens from three pairs of the medial tibia of an anterior cruciate ligament transection canine model were subjected to microMRI and PLM study 12 weeks after surgery. For each specimen, the following experiments were carried out: (a) two dimensional microMRI images of T(2) relaxation at four orientations; (b) the tangent Young's modulus; and (c) two dimensional PLM images of optical retardance and fibril angle. Disease induced changes in tissue were examined across the depth of the cartilage at a microMRI resolution of 13.7-23.1 microm. RESULTS: Several distinct changes from T(2) weighted images of cartilage in OA tibia were seen. For the specimens that were covered at least in part by the meniscus, the significant changes in microMRI included a clear shift in the depth of maximum T(2) (21-36%), a decrease in the superficial zone thickness (37-38%), and an increase in cartilage total thickness (15-27%). These microMRI changes varied topographically in the tibia surface because they were not significant in completely exposed locations in medial tibia. The microMRI results were confirmed by the PLM measurements and correlated well with the mechanical measurements. CONCLUSION: Both microMRI and PLM can detect quantitatively changes in collagen fibre architecture in early OA and resolve topographical variations in cartilage microstructure of canine tibia.

Animals↗