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At least 829 records · Page 46Linked to original sources

PubMed1992

[Use of automated quantitative analysis of electroencephalograms in the diagnosis of dementia].

The submitted paper demonstrates the differential diagnostic value of automatic quantitative analysis of electroencephalograms in the diagnosis of dementia and functional mental disorders in old age. By quantitative autoregression analysis of electric activity of the brain in a group of 53 hospitalized patients (incl. 33 cases of dementia) the conclusions of visual analysis were confirmed as well as the comparability of results obtained by other methods of automatic analysis. Signs characterizing the electroencephalogram in dementia (reduced ratio of alpha activity and increase of slow activity, low value of A/T index, shift of the peak frequency towards slow activity) make differential diagnosis of dementia in organic diseases from pseudodementia possible. Analysis of the results indicates that automatic analysis can be very successful in the detection of Alzheimer's disease.

Aged↗

PubMed2003

Visualisation and navigation methods for typed protein-protein interaction networks.

Protein-protein interactions form large and complex networks. Their visualisation can aid biologists in gaining new insights about the processes in cells and is, therefore, very useful for building sophisticated research tools. Often standard force-directed graph drawing algorithms are used for the visualisation of these networks. However, currently available visual interfaces to biological databases only show general interactions and cannot cope well with more complex networks with different types of interactions. This paper presents a new approach to the visual analysis of protein-protein interaction networks. It uses a combination of circular and force-directed graph drawing algorithms to compute visual representations of protein networks depending on the type of the selected interaction. Smooth transitions between subsequent drawings enable users to explore different functional clusters in these networks without getting lost in the entire network. The visualisation system has been tested with data from the BRITE database.

Algorithms↗

PubMedDate not supplied

[Correlations between changes in hearing and cerebral hemodynamics in patients with chronic alcoholism].

Seventy eight chronic alcoholics, aged 19 to 50 years, were exposed to audiologic and rheoencephalographic examinations. Tone hearing impairment was found in all subjects. The recruitment or greater than normal increment of loudness was primarily identified in patients of Group 1 that comprised those who consumed alcohol from 1 to 10 years. Rheoencephalographic examinations showed decreases of the rheographic index as well as the tone of large and medium caliber arteries in all patients. Group 2 patients who consumed alcohol for more than 10 years displayed greater changes in the vessel tone than Group 1 patients. Analysis of rheoencephalographic waves demonstrated that peripheral and venous tone was decreased in Group 1 patients and increased in Group 2 alcoholics. Visual analysis of rheoencephalographic waves showed lability in the vessel tone of Group 1 patients and a trend for a vessel spasm in Group 2 patients. The results give evidence that Group 1 chronic alcoholics develop toxic lesions of receptors of the hearing organ which is confirmed by the occurrence of recruitment, sound perception impairment, close to normal speech discrimination and insignificant changes in cerebral hemodynamics. Group 2 alcoholics develop marked disorders in cerebral hemodynamics leading to changes in central and intermediate compartments of the hearing organ.

Adult↗

PubMed1998

Quantitative assessment of transient regional ischemia during rotational atherectomy.

UNLABELLED: Sustained myocardial ischemia with angina pectoris, electrocardiographic changes and subsequent non-Q-wave infarctions has been reported during percutaneous transluminal rotational atherectomy of complex coronary lesions. The purpose of this study was to evaluate the effect of rotational atherectomy on regional myocardial perfusion as assessed by serial 99mTc-sestamibi SPECT imaging with semiquantitative tracer uptake analysis. METHODS: Twenty-nine consecutive patients with anginal symptoms, complex coronary lesions (all Type B and Type C) and preserved left ventricular function were studied using resting 99mTc-sestamibi SPECT before rotational atherectomy, during and 2 days after the procedure. For semiquantitative computerized analysis, the left ventricular myocardium was divided into 24 regions, and regional perfusion was expressed as percentage of maximal sestamibi uptake. RESULTS: Visual analysis of scintigraphic images revealed transient perfusion defects corresponding to the revascularized vessel in 26 of 29 patients, whereas three patients had no transient hypoperfusion. During rotational atherectomy, perfusion decreased significantly (>2 s.d. below normal mean) in 3.1 +/- 2.4 regions (range 1-10). Perfusion in the territory of the revascularized vessel was 75% +/- 11% at baseline, decreased to 67% +/- 12% during rotational atherectomy (p < 0.001) and normalized again after rotational atherectomy to 78% +/- 8% (p < 0.001). Similarly, perfusion in the region with the maximal reduction decreased from 74% +/- 15% at baseline to 55% +/- 14% (p < 0.001) during the procedure and returned to 74% +/- 16% (p < 0.001) following the intervention. In calcified stenoses, the extent of perfusion defects was larger as compared to noncalcified (4.2 +/- 2.5 versus 2.3 +/- 2.0 regions/patient, p < 0.05). CONCLUSION: During rotational atherectomy, myocardial hypoperfusion occurs. The transient nature of this perfusion defect can be demonstrated and quantified by serial 99mTc SPECT. This model may prove useful to assess the effects of pharmacological approaches to reducing myocardial hypoperfusion during coronary rotational atherectomy.

Atherectomy, Coronary↗

PubMed1997

Breast imaging with fluorine-18-FDG PET: quantitative image analysis.

UNLABELLED: This study evaluated various quantitative criteria for analysis of breast imaging with PET using the radiolabeled glucose analog 18F-fluorodeoxyglucose (FDG). METHODS: In a prospective study, 73 patients with abnormal mammography or palpable breast masses scheduled for biopsy were investigated with PET. A total of 97 breast tumors were evaluated by histology, including 46 benign and 51 malignant tumors. Using a whole-body PET scanner, attenuation-corrected images were acquired between 40 and 60 min after tracer injection. For Patlak analysis, dynamic data acquisition was obtained in 24 patients. To differentiate between benign and malignant breast tumors, receiver operating characteristic curves were calculated using incrementally increasing threshold values for tumor/ nontumor ratios based on average and maximum activity values per region of interest, standardized uptake values (corrected for partial volume effect, normalized to blood glucose, partial volume effect and blood glucose, using the lean body mass as well as the body surface area) and calculating the FDG influx rate (K) assessed by Patlak analysis. RESULTS: Quantification of FDG uptake in breast tumors provided objective criteria for differentiation between benign and malignant tissue with similar diagnostic accuracy as compared with visual analysis. Applying correction for partial volume effect and normalization by blood glucose yielded the highest diagnostic accuracy. CONCLUSIONS: These quantitative methods provided accurate evaluation of PET data for differentiating benign from malignant breast tumors. Quantitative assessment is recommended to complement visual image interpretation with the potential benefit of reduced interobserver variability.

Breast Diseases↗

PubMedDate not supplied

An approach to comparative analysis of chromatographic fingerprints for assuring the quality of botanical drugs.

The present study was focused on developing the chemometric methods for analysis of the chromatographic fingerprint to control the quality of botanical drugs, which has gained attention in Asia and other countries. We developed a novel approach to generate a set of fingerprint features, called Fisher components (FCs) that were extracted from the chromatographic fingerprint. The method greatly reduces the dimensionality of the fingerprint vector, and the resulting FCs still retain most discriminatory information of the original fingerprint. Choosing an example of relevance to contemporary botanical drugs, we applied the FCs to a set of Shenmai injection samples. We successfully identified the manufacturers of the samples using two classifiers, linear discriminant analysis (LDA) and k-Nearest Neighbor (k-NN) based on the FCs. We also applied a similarity assessment together with the visual analysis using the FCs to exam the products from different manufacturers. We found that the lot-to-lot consistency of products can be accurately determined using the FCs. Finally, we demonstrated that the application of chemometric methods for chromatographic fingerprinting offers reliability to detect suspected fraud samples. In summary, we demonstrated that the presented approaches could be useful to determine the identity, consistency, and authenticity of Shenmai injection through chromatographic fingerprinting. The methods are equally applicable to other botanical drugs.

Chromatography↗

PubMed1995

Neural mechanisms of visual selective attention.

Visual selective attention improves our perception and performance by modifying sensory inputs at an early stage of processing. Spatial attention produces the most consistent early modulations of visual processing, which can be observed when attention is voluntarily allocated to locations. These effects of spatial attention are similar when attention is cued in a trial-by-trial, or sustained, fashion and are manifest as changes in the amplitudes, but not the latencies, of evoked neural activity recorded from the intact human scalp. This modulation of sensory processing first occurs within the extrastriate visual cortex and not within the striate or earlier subcortical processing stages. These relatively early spatial filters alter the inputs to higher stages of visual analysis that are responsible for feature extraction and ultimately object perception and recognition, and thus provide physiological evidence for early precategorical selection during visual attention. Moreover, the physiological evidence extends early selection theories by providing neurophysiologically precise information about the stages of visual processing affected by attention.

Arousal↗

PubMed2005

[The application of 18F-fluorodeoxyglucose positron emission tomography in the diagnosis and staging of lung cancer].

OBJECTIVE: To study the clinical value of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in the diagnosis and staging of lung cancer. METHODS: Ninety-four patients with lung nodular changes were examined by CT, 18F-FDG PET and pathology, cytology. 18F-FDG PET images were analyzed by semi-quantitative standard uptake value (SUV) only and (or) SUV plus visual observation. Focuses with a SUV > 2.5 were judged as malignant changes, while SUV < or = 2.5 was judged as benign. SUV plus visual analysis, based on the focal SUV, the nodular size and shape, and clinical data, was carried out by two nuclear doctors. CT imaging was interpreted by two radiological doctors. The sensitivity, specificity, accuracy, positive predictive and negative predictive values of 18F-FDG PET and CT in the diagnosis, and in the evaluation of lymphatic metastasis and remote metastasis of lung lesions were calculated. The diagnostic efficiency of the two methods (SUV or visual plus SUV method) was compared. RESULTS: (1) 58 cases were confirmed to be malignant by surgery or pathological examination, while 36 cases were proved benign by pathology or empirical therapy. (2) The sensitivity, specificity, accuracy, positive and negative predictive values were 69%, 65%, 68%, 82% and 49% respectively for CT; and 91%, 89%, 90%, 93% and 87% respectively for SUV analysis; and 95%, 94%, 95%, 97% and 92% respectively for visual plus SUV methods. (3) Among 34 patients with mediastinal lymph node involvement confirmed by pathology, 18F-FDG PET detected 30 cases, while CT detected only 18 cases (P < 0.01). (4) 18F-FDG PET revealed 19 cases with distant metastases, while CT only discovered 8 cases with distant metastases. As a result, the therapy was modified by PET examination in 14 patients. CONCLUSION: 18F-FDG PET imaging is of important clinical value in the diagnosis of lung lesions and the staging of malignancy.

Adolescent↗

PubMed2001

Effect of soldering on metal-porcelain bond strength in repaired porcelain-fused-to-metal castings.

STATEMENT OF PROBLEM: Chemical bonding plays a major role in the adherence between metal and porcelain. The formation of an oxide layer on solder material has not been described in the literature. It is unknown whether the application of solder negatively affects the bond strength between porcelain and metal. PURPOSE: This in vitro study assessed the effect of solder on the bond strength between metal and porcelain. MATERIAL AND METHODS: Forty 20 x 6 x 0.5 mm patterns were divided into test (20) and control (20) groups. Test samples were perforated and repaired with solder, and 2 layers of opaque and dentin porcelain subsequently were applied on all samples. The samples were subjected to a 3-point flexural test on a screw-driven mechanical testing machine at a crosshead speed of 0.5 mm/min. Failure type (adhesive vs cohesive) was quantified by digitizing photographs of test and control samples. Three samples in each group also were examined with an SEM coupled with an x-ray energy-dispersive spectroscopy apparatus (SEM/EDS). Means and standard deviations of loads at failure, sample thickness, and surface area covered with porcelain were calculated, and data were analyzed with Student t test (P < or = 0.05). RESULTS: The mean fracture load for test samples was significantly greater than for control samples (P = 0.0038). Test samples also were significantly thicker (mean thickness difference 0.14 mm) (P = 0.0001). When the data were controlled for thickness by using a multiple linear regression analysis, no significant difference was found (P = 0.68). Test samples had a greater surface area covered with opaque porcelain (P = 0.0006) as determined by visual inspection. CONCLUSION: In this study, soldered and nonsoldered samples did not show any significant difference in porcelain-to-metal bond strength. Visual analysis revealed a significant difference in the amount of porcelain remaining on the fracture surface of the test and control samples; a complete quantitative elemental analysis with SEM/EDS is in progress.

Dental Porcelain↗

PubMed1991

Quantitative analysis of protein deposits on hydrophilic soft contact lenses: I. Comparison to visual methods of analysis. II. Deposit variation among FDA lens material groups.

Patient-worn lenses (N = 1058) were evaluated using both the Rudko method for deposit typing and a quantitative assay for adsorbed protein. The visible deposit typing results were compared to the values obtained by the quantitative assay. The Rudko method for deposit classification was found to be a poor quantitative measure of deposited protein. Statistical differences were found between protein levels on lenses with identical Rudko scores among the FDA lens groups. In many cases, no meaningful correlation was found between Rudko scores and protein levels for lenses within the same FDA lens group. Significant differences in the distribution of visible deposits (Rudko scores) were found among the four FDA lens groups. Significant differences were also found in the quantity of adsorbed protein among FDA lens groups.

Contact Lenses, Hydrophilic↗

PubMed2006

Blind source separation for the computational analysis of dynamic oncological PET studies.

The analysis of dynamic positron emission tomography (PET) studies provides clinically useful parametric information, but often requires complex and time-consuming compartmental or non-compartmental techniques. Independent component analysis (ICA), a statistical method used for feature extraction and signal separation, is applied to dynamic PET studies to facilitate the initial interpretation and visual analysis of these large image sequences. ICA produces parametric images, where structures with different kinetic characteristics are assigned opposite values and readily discriminated, improving the identification of lesions and facilitating the posterior detailed kinetic analysis.

Algorithms↗

PubMed2001

[Clinical application of gated SPECT imaging to regional function assessment: current status and limitations].

It is likely that clinical applications of ECG-gated single-photon emission computed tomography (SPECT) are established in nuclear cardiology practice because of the improved diagnostic accuracy of gated SPECT imaging for the detection of coronary artery disease and because this technique enables not only simultaneous assessment of myocardial perfusion and function but also improvement of risk stratification of coronary patients. Although a gated approach with SPECT imaging has been demonstrated to have high reproducibility and reliability for quantifying global function, there are several limitations in appropriate processing of 4-dimensional data for quantitative assessment of regional function. Even if limited spatial and temporal resolutions and a lack of attenuation and scatter corrections are disregarded, sufficient data collection, image-quality control, and precise application of algorithms to gated SPECT data are prerequisite. The results of several kinds of quantitative analysis of regional cardiac function, such as regional wall motion (distance deviation of the inner myocardial border), regional ejection fraction, percent wall thickening, and percent count increase with or without self-normalization have been reported. Further clinical application of quantitative regional function assessment by a gated SPECT technique, however, requires standardization of data acquisition, data analysis, and data presentation with appropriate quantitative parameters; production of a standard map using quantitative values; and validation study by comparison with results of visual analysis and other modalities in a large-scale patient population.

Algorithms↗

PubMedDate not supplied

Teleplot: a computing system for objective analysis of fetal heart rate recordings.

In human pregnancies, fetal heart rate recordings are useful both in predicting and in preventing imminent fetal death. Although an objective numerical measurement of such recordings is preferable to visual analysis, few obstetric centres have the computer expertise to implement this. Here we describe the principles of a technique whereby the fetal heart rate versus time trace may be transferred into computer memory for further processing in a numerical and objective fashion. The methodology is valid howsoever the fetal heart rate is detected.

Computers↗

PubMed2002

Schema design and implementation of the grasp-related mirror neuron system.

Mirror neurons within a monkey's premotor area F5 fire not only when the monkey performs a certain class of actions but also when the monkey observes another monkey (or the experimenter) perform a similar action. It has thus been argued that these neurons are crucial for understanding of actions by others. We offer the hand-state hypothesis as a new explanation of the evolution of this capability: the basic functionality of the F5 mirror system is to elaborate the appropriate feedback - what we call the hand state - for opposition-space based control of manual grasping of an object. Given this functionality, the social role of the F5 mirror system in understanding the actions of others may be seen as an exaptation gained by generalizing from one's own hand to an other's hand. In other words, mirror neurons first evolved to augment the "canonical" F5 neurons (active during self-movement based on observation of an object) by providing visual feedback on "hand state," relating the shape of the hand to the shape of the object. We then introduce the MNS1 (mirror neuron system 1) model of F5 and related brain regions. The existing Fagg-Arbib-Rizzolatti-Sakata model represents circuitry for visually guided grasping of objects, linking the anterior intraparietal area (AIP) with F5 canonical neurons. The MNS1 model extends the AIP visual pathway by also modeling pathways, directed toward F5 mirror neurons, which match arm-hand trajectories to the affordances and location of a potential target object. We present the basic schemas for the MNS1 model, then aggregate them into three "grand schemas" - visual analysis of hand state, reach and grasp, and the core mirror circuit - for each of which we present a useful implementation (a non-neural visual processing system, a multijoint 3-D kinematics simulator, and a learning neural network, respectively). With this implementation we show how the mirror system may learn to recognize actions already in the repertoire of the F5 canonical neurons. We show that the connectivity pattern of mirror neuron circuitry can be established through training, and that the resultant network can exhibit a range of novel, physiologically interesting behaviors during the process of action recognition. We train the system on the basis of final grasp but then observe the whole time course of mirror neuron activity, yielding predictions for neurophysiological experiments under conditions of spatial perturbation, altered kinematics, and ambiguous grasp execution which highlight the importance of the timing of mirror neuron activity.

Animals↗

PubMed1988

Preliminary studies on scoring micronuclei by computerised image analysis.

Initial studies of the use of computerised image analysis to determine micronucleus frequencies in human lymphocytes that have completed one nuclear division are described. Two methods, based on (a) bromodeoxyuridine incorporation and (b) cytokinesis blocking with cytochalasin-B, were studied. The former method is directly amenable to automation. Cytokinesis-blocked cells could not be automatically recognised by image analysis but it was possible to obtain the correct micronucleus frequency from the integrated optical density histograms by using the mononucleate/binucleate cell ratio obtained by visual analysis. The mean (+/- 1 S.E.) integrated optical density of X-ray-induced micronuclei was 11.2% (+/- 1.1) of that measured for nuclei of G1 cells.

Automation↗

PubMed2005

Neural mechanisms underlying target selection with saccadic eye movements.

In exploring the visual scene we make about three saccadic eye movements per second. During each fixation, in addition to analyzing the object at which we are looking, a decision has to be made as to where to look next. Although we perform this task with the greatest of ease, the computations to perform the task are complex and involve numerous brain structures. We have applied several investigative tools that include single-cell recordings, microstimulation, pharmacological manipulations and lesions to learn more about the neural control of visually guided eye saccadic movements. Electrical stimulation of the superior colliculus (SC), areas V1 and V2, the lateral intraparietal sulcus (LIP), the frontal eye fields (FEF) and the medial eye fields (MEF) produces saccadic eye movements at low current levels. After ablation of the SC, electrical microstimulation of V1, V2, and LIP no longer elicits saccadic eye movements whereas stimulation of the FEF and MEF continues to be effective. Ablation of the SC but not of the FEF eliminates short-latency saccadic eye movements to visual targets called "express saccades," whereas lesions of the FEF selectively interfere with target selection. Bilateral removal of both the SC and the FEF causes major, long lasting deficits: all visually elicited saccadic eye movements are eliminated. In intact monkeys, subthreshold electrical microstimulation of the FEF and MEF as well as the lower layers of V1 and V2 and of some subregions of LIP greatly facilitates the choice of targets presented in the receptive fields of the stimulated neurons. By contrast, stimulation of the upper layers of V1 and V2 and other sub-regions of LIP produces a dramatic interference in target selection. Examination of the role of inhibitory circuits in eye-movement generation reveals that local infusion of muscimol, a GABA (gamma-aminobutyric acid) agonist, or bicuculline, a GABA antagonist, interferes with target selection in V1. On the other hand, infusion of bicuculline into the FEF produces facilitation in target choice and irrepressible saccades. It appears therefore that inhibitory circuits play a central role in visual analysis in V1 and in the generation of saccadic eye movements in the FEF. It is proposed that two major streams can be discerned in visually guided eye-movement control, the posterior from occipital and parietal cortex that reaches the brainstem via the SC and the anterior from the FEF and MEF that has direct access to the brainstem oculomotor centers.

Animals↗

PubMed2006

Transmission network analysis to complement routine tuberculosis contact investigations.

OBJECTIVE: We examined the feasibility and value of network analysis to complement routine tuberculosis (TB) contact investigation procedures during an outbreak. METHODS: We reviewed hospital, health department, and jail records and interviewed TB patients. Mycobacterium tuberculosis isolates were genotyped. We evaluated contacts of TB patients for latent TB infection (LTBI) and TB, and analyzed routine contact investigation data, including tuberculin skin test (TST) results. Outcomes included number of contacts identified, number of contacts evaluated, and their TST status. We used network analysis visualizations and metrics (reach, degree, betweenness) to characterize the outbreak. RESULTS: secondary TB patients and more than 1200 contacts. Genotyping detected a 21-band pattern of a strain W variant. No HIV-infected patients were diagnosed. Contacts prioritized by network analysis were more likely to have LTBI than nonprioritized contacts (odds ratio=7.8; 95% confidence interval=1.6, 36.6). Network visualizations and metrics highlighted patients central to sustaining the outbreak and helped prioritize contacts for evaluation. CONCLUSIONS: A network-informed approach to TB contact investigations provided a novel means to examine large quantities of data and helped focus TB control.

Adolescent↗

PubMed1989

Sleep EEG evaluation: a comparison of results obtained by visual scoring and automatic analysis with the Oxford sleep stager.

Oxford Medical has introduced an automatic sleep stager based on the stage-scoring criteria by Rechtschaffen and Kales. With our study we intended to examine whether the results of the stager (version 3.0) match those of the visual evaluation by two independent raters. We also wanted to test the reliability of this automatic sleep stage-scoring system. Ten somnopolygrams of subjects without sleep disturbances served as a basis for the comparison. Each sleep recording was scored twice automatically by the stager, twice visually by the first rater, and once by the second rater. The two automatic analyses of the somnopolygrams differed by 4.3% in a total of 13,850 epochs (1 epoch delta 20 s) regarding sleep stage scoring. The difference between the first and the second visual evaluation by the same rater amounted to 5.7%, whereas the results of the two independent raters deviated by 8.7%. Compared with the results of the visual analysis reached as a consensus by both raters--the so-called optimized visual analysis--the stager showed a 26.9% difference. The automatic analysis scored fewer epochs as stages wake, rapid eye movement (REM), and 2 and more as stages 1, 3, and 4. The sleep stager's frequent difficulty in identifying stage wake correctly as well as its incorrect allocation to other stages--mainly stage REM--could lead to misinterpretations of sleep recordings, whereas the increase in stages 1, 3, and 4, as compared with visual scoring, was negligible.

Adult↗