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PubMed1995

Computerized analysis of interstitial infiltrates on chest radiographs: a new scheme based on geometric pattern features and Fourier analysis.

RATIONALE AND OBJECTIVES: Detection of interstitial infiltrates on chest radiographs is difficult and subjective. Therefore, we developed a computerized method to provide quantitative analysis of lung texture to increase diagnostic accuracy. METHODS: Two hundred chest radiographs--100 healthy and 100 abnormal with interstitial infiltrates--were digitized using a laser scanner. They were analyzed by an automated computerized scheme that uses a combination of two methods for detection of interstitial infiltrates: a lung texture analysis based on the Fourier transform and a geometric pattern feature analysis based on filtering techniques. RESULTS: The overall sensitivity and specificity of the computerized scheme were 92% and 90%, respectively. The scheme achieved a sensitivity of 80% in subtle cases (n = 15) and 88% in cases with localized interstitial disease (n = 26), whereas the specificity remained unchanged. There was good correlation between the computer output and the radiologists' severity rating. CONCLUSION: This enhanced computerized scheme exhibits high sensitivity and specificity with a large database.

Adolescent↗
PubMed1998

Polymerase chain reaction based assessment of leukoreduction efficacy using a cytomegalovirus DNA transfected human T-cell line.

BACKGROUND AND OBJECTIVES: Detection of CMV DNA by PCR in seropositive blood donors is affected by nucleic acid extraction, amplification conditions and PCR product detection sensitivity. Clinical studies have shown that leukoreduced blood products are as effective as CMV-seronegative blood products in minimizing transfusion-associated CMV infection. We developed a PCR-based test model to assess the efficacy of leukoreduction on the removal of CMV DNA from blood donations. MATERIALS AND METHODS: Whole blood units were spiked with a human Jurkat T-lymphocyte cell line which had been stably transfected with a CMV DNA immediate early sequence. All blood units were either CMV seronegative or shown to be CMV PCR negative. The amount of CMV DNA by PCR before, during and after filtration of blood units with third-generation leukocyte reduction filters were determined using a semi-quantitative adaptation of the Digene SHARP Signal System Assay (DSSSA). RESULTS: Whole blood units spiked with 1-2 x 10(6) CMV transfected Jurkat cells contained no detectable CMV DNA after leukoreduction. With a higher inoculum of 2.9 x 10(8) transfected Jurkat cells per unit, CMV DNA was detected after leukoreduction; however, there was an approximate 3 log decrease in the amount of CMV DNA detected. CONCLUSION: This CMV DNA transfected human Jurkat cell line in conjunction with semi-quantitative CMV PCR may be used to model leukoreduction efficacy and provides evidence that leukoreduction of blood products can decrease the amount of cellular CMV DNA by approximately 3 logs.

Cytomegalovirus↗
PubMed2001

Subliminal visual oddball stimuli evoke a P300 component.

OBJECTIVE: To provide evidence that a P300 component can be elicited by subliminal stimuli in an oddball paradigm. METHODS: The words LEFT and RIGHT were presented in a frequent-rare ratio (80-20%), counterbalanced between subjects. Stimuli were presented at the objective detection threshold (d'=0, via unmasked 1 ms presentations), a stringent measure for detecting any conscious perception. RESULTS: A significantly larger amplitude component was found for rare vs. frequent stimulus presentations across electrodes Fz, Cz, and Pz using both a broad 200-900 ms window (F(1,27)=5.75, P<0.012, eta(2)=0.18; one-tailed), and a more narrow 400-760 ms window defined using principal component analysis (F(1,27)=10.10, P<0.002, eta(2)=0.27; one-tailed). No significant component latency effects were found. An analysis of the conscious perception index (d') and the oddball effect (rare-frequent amplitude difference) revealed a negative relationship, further supporting the contention that conscious perception does not account for the finding, and suggesting that any conscious stimulus detection may inhibit this subliminal effect. CONCLUSIONS: Results provide evidence that an endogenous component can be elicited by undetectable subliminal stimuli in an oddball paradigm. Implications are discussed for comparing conscious and unconscious information processing, unconscious learning, and the measurement of ERPs to subliminal stimuli.

Adult↗
PubMed2003

Behavioral phenotype of the reeler mutant mouse: effects of RELN gene dosage and social isolation.

Reeler (rl/rl) and reeler/wild-type (+/rl) mice synthesize Reln at subnormal rates, as do patients with schizophrenia, bipolar disorder, and autism, thereby forming the basis for a Reln hypothesis for vulnerability to these psychopathologies and justifying attention to the behavioral phenotypes of Reln-deficient mice. Tests of gait, emotionality, social aggression, spatial working memory, novel-object detection, fear conditioning, and sensorimotor reflex modulation revealed the behavioral phenotype of rl/rl, but not +/rl, mice to be different from that of wild-type (+/+) mice. These results reveal no effect of Reln gene dosage and provide significant challenges to both the Reln and the neurodevelopmental hypotheses of the etiology of major psychopathologies.

Analysis of Variance↗
PubMed1996

Estimation of self-motion by optic flow processing in single visual interneurons.

Humans, animals and some mobile robots use visual motion cues for object detection and navigation in structured surroundings. Motion is commonly sensed by large arrays of small field movement detectors, each preferring motion in a particular direction. Self-motion generates distinct 'optic flow fields' in the eyes that depend on the type and direction of the momentary locomotion (rotation, translation). To investigate how the optic flow is processed at the neuronal level, we recorded intracellularly from identified interneurons in the third visual neuropile of the blowfly. The distribution of local motion tuning over their huge receptive fields was mapped in detail. The global structure of the resulting 'motion response fields' is remarkably similar to optic flow fields. Thus, the organization of the receptive fields of the so-called VS neurons strongly suggests that each of these neurons specifically extracts the rotatory component of the optic flow around a particular horizontal axis. Other neurons are probably adapted to extract translatory flow components. This study shows how complex visual discrimination can be achieved by task-oriented preprocessing in single neurons.

Animals↗
PubMed2003

New paediatric contrast test: Hiding Heidi low-contrast 'face' test.

BACKGROUND: The Hiding Heidi low-contrast 'face' test is a new paediatric contrast test to evaluate the ability to detect objects with low contrast. The purpose of the present study was to compare the Hiding Heidi low-contrast 'face' test (HH) with the Pelli-Robson contrast sensitivity test (PR) and the functional acuity contrast test (FACT) in the low-contrast assessment. METHODS: Thirty university students participated in the present study. The contrast ability was evaluated by using three different methods: HH, PR and FACT. The HH was repeated on two separate occasions to test the repeatability. RESULTS: There was a significant positive correlation between HH and PR (r = 0.65, P < 0.01); between HH and FACT at 6 cycles per degree (c.p.d.; r = 0.64, P < 0.01); between HH and FACT at 3 c.p.d. (r = 0.91, P < 0.01); and between HH and FACT at 1.5 c.p.d. (r = 0.56, P < 0.01). The paired t-test showed a significant difference between HH and PR (t = -6.05, P < 0.01); between HH and FACT at 6 c.p.d. (t = -11.16, P < 0.01); between HH and FACT at 3 c.p.d. (t = -8.35, P < 0.01); and between HH and FACT at 1.5 c.p.d. (t = -5.64, P < 0.01). They had good agreement. The HH had a high repeatability. CONCLUSIONS: The HH had a positive correlation but produced significantly different readings when compared with FACT and PR. The features and role of HH in clinical contrast sensitivity assessment are discussed.

Adult↗
PubMed2000

Assessment of the chronotropic response at the anaerobic threshold: an objective measure of chronotropic function.

The evaluation of the heart rate response to exercise is important for the diagnosis of chronotropic incompetence and the assessment of a rate responsive algorithm of sensor-controlled pacemakers. The aim of the present study was to examine a classification of the chronotropic response at an individually moderate exercise level. Sixteen pacemaker patients (patient group, age 62.9 +/- 7.6 years) with sick sinus syndrome and 15 age-matched healthy subjects (control group, age 57.6 +/- 9.4 years) underwent a maximum cardiopulmonary exercise test on a treadmill after a protocol with individually selected incremental steps. To analyze the patients' intrinsic heart rate response, the rate responsive mode of the pacemaker was switched off. Chronotropic incompetence was diagnosed in eight patients whose maximal heart rate was < 80% of the age-predicted heart rate. The heart rate at the anaerobic threshold was significantly lower in the chronotropically incompetent subgroup than in the chronotropically competent patients and the healthy subjects (85.9 +/- 6.6 beats/min vs 100.3 +/- 9.9 beats/min and 112.9 +/- 11.7 beats/min, respectively). The chronotropic slope of the heart rate reserve as a function of the metabolic reserve was significantly higher in the control group than in the patient groups with either mild or severe chronotropic incompetence (0.94 +/- 0.17 vs 0.64 +/- 0.08 and 0.43 +/- 0.14, respectively). Furthermore, the chronotropically incompetent response could be divided into a linear type with and without a threshold, an exponential, and a logarithmic type. The anaerobic threshold was an objectively detectable breakpoint at an individually moderate exercise level that could be used for characterization of chronotropic function. At the anaerobic threshold, a physiological heart rate response was about 220--age--50 beats/min. A deviation of more than 10 beats/min below this physiological value characterized chronotropic incompetence.

Algorithms↗
PubMed1999

Comparison of prenatal ultrasound and postmortem findings in fetuses and infants with congenital heart defects.

OBJECTIVE: Detection of congenital heart defects by prenatal ultrasound examination has been one of the great challenges since the investigation for fetal anomalies became part of the routine fetal examination. This prospective study was designed to evaluate the concordance of prenatal ultrasound findings with autopsy examination in a population consisting of both referred women and non-selected pregnant women. DESIGN: Criteria for inclusion were an ultrasound examination at the National Center for Fetal Medicine and an autopsy performed during the years 1985-94. Results from the ultrasound and autopsy examinations were systematized into categories depending on the degree of concordance. RESULTS: Of 408 infants and fetuses with developmental anomalies, 106 (26%) had congenital heart defects. In 63 (59%) of these 106 cases, the heart defect was the principal reason for the termination of pregnancy or the cause of death. Excluding five cases with a secundum atrial septal defect, there was complete agreement between the ultrasound examination and the autopsy findings in 74 (73%) of 101 cases. In 18 cases, there were minor discrepancies between ultrasound and autopsy findings. The main diagnosis was thus correct in 92 cases (91%). From the first time period (1985-89) to the second (1990-94), the detection rate of all heart defects increased from 48% to 82%. CONCLUSION: This study confirms a good correlation between ultrasound and autopsy diagnoses in fetuses and infants with congenital heart defects. A significant improvement in the detection of heart defects occurred from the first time period to the second and was probably due to increased experience and technical advances.

Abnormalities, Multiple↗
PubMed2000

Fetuses and infants with congenital urinary system anomalies: correlation between prenatal ultrasound and postmortem findings.

OBJECTIVE: Detection of congenital urinary system anomalies is an important part of the prenatal ultrasound examination. The present study compares prenatal ultrasonographic findings and postmortem examinations of fetuses and infants with renal and urinary tract anomalies. DESIGN: Criteria for inclusion were an ultrasound examination at the National Center for Fetal Medicine (Trondheim, Norway) and autopsy performed during the period 1985-94. Results from the ultrasound examination and autopsy regarding urinary system anomalies were categorized according to the degree of concordance. RESULTS: Urinary system anomalies were found in 112 (27%) of 408 fetuses with congenital anomalies. The renal and/or urinary tract anomaly was the principal reason for induced abortion or cause of death in 50 cases (45%). In 97 (87%) of the 112 cases there was full agreement between the ultrasound observations and the autopsy findings. In five cases the autopsy revealed minor findings not mentioned in the ultrasound report. The main diagnosis was thus correct in 102 cases (91%). In four cases major autopsy findings had not been found by ultrasound examination; in another four, none of the autopsy findings were suspected by ultrasound, and in two, minor ultrasound findings were not confirmed at autopsy. CONCLUSIONS: The accordance between ultrasound diagnoses and postmortem examinations proved to be satisfactory. The close co-operation between ultrasonographers and perinatal pathologists is mutually beneficial. In addition to complementing prenatal diagnosis, postmortem examination is of vital importance for the quality control of ultrasonography in fetal diagnosis and plays an important role in genetic counseling.

Autopsy↗
PubMed2006

[Transient elastography for diagnosing liver cirrhosis].

BACKGROUND AND OBJECTIVE: Detection of liver cirrhosis has numerous implications because of the potential sequelae of cirrhosis. Transient elastography (Fibroscan), was evaluated as a novel, non-invasive means of assessing cirrhosis by measuring liver stiffness. METHODS: 147 consecutive patients with different forms of liver disease and histologically determined stages of liver fibrosis were prospectively studied by transient elastography. 48 patients had liver cirrhosis. RESULTS: The number of transient elastographic measurements per patient was 12+/-4 (range 6 - 30). Valid elastography measurements were available for 135 out of 147 patients (92 %). The results of transient elastography correlated positively with the histological score of liver fibrosis (r = 0.8; 95 % CI: 0.72 - 0.85; p < 0.001). Areas under the receiver operating characteristic curve (AUROC) were 0.91 for > or = F3 fibrosis (95 % CI: 0.85 - 0.96) and 0.94 for cirrhosis (95 % CI: 0.90 - 0.98). Using a cut-off value of 13 kPa for detection of liver cirrhosis a sensitivity of 90 %, a specificity of 82 %, a positive predictive value of 71 % and a negative predictive value of 95 % were obtained. CONCLUSIONS: Measuring liver stiffness by transient elastography proved to be an easy method to assess liver cirrhosis. In combination with clinical signs, ultrasound and biochemical markers noninvasive diagnosis of liver cirrhosis will be further improved.

Adolescent↗
PubMedDate not supplied

[Mobilization of the partially stiff shoulder under anesthesia (ankylosing humeroscapular periarthritis)].

"Humeroscapular periarthritis" (HPA) was first described by Duplay in 1872 and is to be understood as a syndrome whose typical symptoms are pain and partial or total stiffness of the shoulder ("ankylosing" HPA). This term includes all regressive and reactive affections occurring in the region of the shoulder joint proper (Refish and van Laack, 1985), and has meanwhile become a synonym for painful shoulder stiffness, a term which covers many different processes which are not covered in detail here. Today, however, thanks to refined clinical and radiological examination methods, it is often possible to detect objectively at least some of the changes and to gain insights into the pathophysiological processes. The goal of treatment of HPA is to restore the function of the shoulder joint and eliminate the pain. To this end, various forms of treatment are fundamentally available: 1) conservative treatment, with medication and physiotherapy; 2) surgical treatment; and 3) mobilization under anesthetic, with which, comparatively speaking, results have been best.

Adult↗
PubMed2001

Radiofrequency spectral analysis of attenuated ultrasound signals in experiments with echo contrast microbubbles.

Conventional gray-scale myocardial contrast echocardiography cannot distinguish perfused but attenuated from nonperfused myocardium because both may appear similar at low image intensity. We hypothesized that with radiofrequency spectral analysis of attenuated ultrasound signals, the harmonic-to-fundamental frequency ratio of the peak power spectrum (HFR(P)) could determine the presence of contrast microbubbles. We measured frequency responses of Optison microbubbles at defined degrees of ultrasound signal attenuation with different formulations of silicone (55D, 80A, and 3M); gray-scale intensities of Optison plus water compared with degassed water were analyzed at different attenuation settings (-25, -32, and -44 dB, respectively). HFR(P) values of Optison plus water were significantly higher than reference values of degassed water at each attenuation setting (55D, -14 +/- 2 dB versus -30 +/- 2 dB, P <.001; 80A, -19 +/- 2 dB versus -30 +/- 3 dB, P <.01; 3M, -22 +/- 2 dB versus -30 +/- 3 dB, P <.05), even though conventional videodensitometric analysis could not distinguish them. HFR(P) analysis objectively detects microbubbles in clinically relevant conditions of attenuation.

Contrast Media↗
PubMed2000

On the frequency spectrum of Amplitude Modulation Following Responses.

Objective detection of Amplitude Modulation Following Responses (AMFR) is based on statistics applied after signal transformation from the time to the frequency domain by means of Discrete Fourier Transformation. In theory the frequency resolution of such transformation depends only on the analysed time window. In practise frequency resolution is also limited by the error caused by minimal difference between the clocks used for stimulus generation and Analogue/Digital-conversion. Small differences in clock frequencies may cause a spread of energy to neighbouring bins. In order to avoid this error we derived the sample clock for the A/D-conversion from the stimulator clock. By means of this technique the frequency structure of the AMFR was investigated. It is shown that if technical induced errors are excluded, the energy of the AMFR-response is limited to a very narrow frequency band. No physiologically induced disturbances of the phase locking of the AMFR to the modulation frequency could be observed. Additionally it is demonstrated that an increase of frequency resolution leads to an improved signal to noise ratio similar to the increase of averages in the time domain.

Adult↗
PubMed1998

Optic neuritis. Doppler ultrasonography compared with MR and correlated with visual evoked potential assessments.

PURPOSE: To establish the role of Doppler ultrasonography (US) in the examination of patients with acute unilateral optic neuritis. MATERIAL AND METHODS: Twenty-five patients with a clinical diagnosis of optic neuritis were prospectively evaluated and 18 of them were included in the study. The inclusion criteria were MR findings of unilateral disease and age below 50 years. All patients were examined with MR in order to objectively detect, localize and measure the optic nerve lesions and in order to exclude patients with unidentifiable optic nerve involvement. Evaluation with US was performed to determine nerve morphology, nerve swelling, and resistance to flow in the central retinal artery. The patients' contralateral optic nerve served as an internal control. The US findings were correlated to the degree of visual impairment, both initially and at follow-up. Visual evoked potential (VEP) assessments were also performed in 16 patients. RESULTS: A statistically significant difference was found in the optic nerve diameter and in the resistance to flow in the central retinal artery between the affected and unaffected eyes. Patients with a prolonged impairment of visual acuity initially had a more swollen nerve and an increased resistance to flow in the affected optic nerve. Prognostic information was also gathered solely by evaluating the unaffected nerve diameter: patients who normally had thinner optic nerves had a more severe form of optic neuritis. VEP assessments were positive in all patients investigated. CONCLUSION: Doppler US can be used together with a VEP assessment as an indicator of the disease process in acute optic neuritis. These methods offer a potential for monitoring patients over time.

Adult↗
PubMed2000

A comparative study on potential cytogenetic fingerprints for radiation LET in human lymphocytes.

PURPOSE: To carry out a comparative study on potential cytogenetic fingerprints for radiation LET in human metaphase lymphocytes. MATERIALS AND METHOD: Human lymphocytes were irradiated in vitro with 3.0 Gy 60Co gamma-rays, 0.9 Gy 3H beta-rays or 0.2 Gy 2.7 Mev neutrons. Detailed chromosome aberrations were analysed by combined FISH with pan-telomere staining and specific whole-chromosome painting (1, 2 and 4). Total chromosome translocations and insertions were also analysed by multicolour whole-chromosome painting (chromosomes 1, 2 and 4 orange, chromosomes 3, 5 and 6 green). RESULTS: Among the six proposed radiation cytogenetic fingerprints, the ratio of total simple translocations to insertions (I-ratio), showed the largest difference between low-LET 60Co gamma-ray and high-LET neutron radiation. The ratios of complete exchanges to incomplete rejoinings [S(I)-ratio] and dicentrics to interstitial deletions (H-ratio), showed a similar significant difference between low- and high-LET radiation. The ratios of centric rings to interstitial deletion (G-ratio) showed a trend of LET-related difference, but the difference was not significant in this data set. The ratios of dicentrics to centric rings (F-ratio) and apparent complete exchanges to hidden complete exchanges [S(II)-ratio], showed no difference between low- and high-LET radiation. In the 1426 radiation-induced chromosome aberrations observed after 52 h culture, evidence for sister-chromatid fusion but not telomere addition was found. CONCLUSION: Pan-telomere staining plus specific whole chromosome painting allows simultaneous and objective detection of complete or incomplete chromosome exchanges and interstitial or terminal deletions in human peripheral lymphocytes. Of the six proposed cytogenetic ratios, the I-ratio is the most effective cytogenetic fingerprint for distinguishing low-LET from high-LET radiation in human metaphase human lymphocytes.

Beta Particles↗
PubMed1995

Determination of optimum injected current patterns in electrical impedance tomography.

The problem of finding the optimum current under different constraints in electrical impedance tomography is cast into a non-linear optimization problem. Optimum currents are investigated for a two-dimensional cylindrical body with a concentric or an eccentric inhomogeneity under the constraints of constant dissipated power and constant total injected current. For a concentric inhomogeneity, it is shown that the opposite drive results in a better distinguishability than the cosine current pattern under the constant-injected-current constraint. The results for the concentric case are extended to the eccentric case directly using the properties of the conformal transformation and of the constraints involved. Distinguishability and the minimum detectable object size achieved by the optimized currents are compared with the ones achieved by the cosine current pattern for conductivity distributions with the concentric and eccentric inhomogeneity.

Electric Impedance↗
PubMed2004

Looking for planetary moons in the spectra of distant Jupiters.

More than 100 nearby stars are known to have at least one Jupiter-sized planet. Whether any of these giant gaseous planets has moons is unknown, but here we suggest a possible way of detecting Earth-sized moons with future technology. The planned Terrestrial Planet Finder observatory, for example, will be able to detect objects comparable in size to Earth. Such Earth-sized objects might orbit their stars either as isolated planets or as moons to giant planets. Moons of Jovian-sized planets near the habitable zones of main-sequence stars should be noticeably brighter than their host planets in the near-infrared (1-4 microm) if their atmospheres contain methane, water, and water vapor, because of efficient absorption of starlight by these atmospheric components. By taking advantage of this spectral contrast, future space observatories will be able to discern which extrasolar giant planets have Earth-like moons capable of supporting life.

Astronomical Phenomena↗
PubMed2003

Identification of previously "undetectable" abnormalities of the bony labyrinth with computed tomography measurement.

BACKGROUND: In patients with congenital sensorineural hearing loss (SNHL), a computed tomography (CT) scan of the temporal bone identifies inner ear malformations in approximately 25%, whereas the inner ear is grossly normal to visual inspection in the remaining 75% of the patients. In the latter group, the hearing loss is often attributed to radiologically undetectable abnormalities of the membranous labyrinth. However, subtle bony malformations may be missed because visual inspection alone is insensitive for detection. OBJECTIVE: To test the hypothesis that there are subtle bony abnormalities of the inner ear in patients with SNHL who are radiologically deemed to have normal otic bone, using standardized measurements of the inner ear. STUDY DESIGN: Retrospective review. METHODS: Measurements of the cochlea, vestibule, and semicircular canals (SCCs) were made on axial and coronal temporal bone CT scans on 15 patients with normal hearing and 15 patients with congenital SNHL and grossly normal temporal bone CT scans. Student's t-test was performed to compare the measurements of the two groups. RESULTS All studies from the SNHL group were deemed normal by visual inspection and standardized measurements (+/-2 SD from normal). Surprisingly, there were significant differences in the measurements of the cochlea and of the SCCs between patients with and without SHNL (P <.05). CONCLUSIONS: As a group, patients with SNHL and a "normal CT scan" have significant differences in the dimensions of the inner ear. This suggests that these patients have disturbed morphogenesis of both membranous and bony labyrinth. This novel observation has important implications for understanding the etiology of SNHL.

Child↗