Relevance of prognostic features in myeloid metaplasia to selection of patients for bone marrow transplantation.
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Bone Marrow Transplantation↗
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Results for “Feature selection”
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Design of a Web interface for anatomical images.
Interactive documents for use with the World Wide Web have been developed for viewing multi-dimensional radiographic and visual images of human anatomy, derived from the Visible Human Project. Emphasis has been placed on user-controlled features and selections. The purpose was to develop an interface which was independent of host operating system and browser software which would allow viewing of information by multiple users. The interfaces were implemented using HyperText Markup Language (HTML) forms, C programming language and Perl scripting language. Images were pre-processed using ANALYZE and stored on a Web server in CompuServe GIF format. Viewing options were included in the document design, such as interactive thresholding and two-dimensional slice direction. The interface is an example of what may be achieved using the World Wide Web. Key applications envisaged for such software include education, research and accessing of information through internal databases and simultaneous sharing of images by remote computers by health personnel for diagnostic purposes.
Anatomy, Cross-Sectional↗
Lumbar support most critical feature to consider during chair selection.
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Biomechanical Phenomena↗
Lymphocytotoxic antibodies in Israeli patients with rheumatoid arthritis.
The presence, antigenic specificity, and clinical role of lymphocytotoxic antibodies (LCAs) were studied in 72 Israeli patients with rheumatoid arthritis (RA). Using the microlymphocytotoxicity assay on a cell panel of 47 donors, LCAs were found in 55% of the 72 RA sera, each displaying a distinct pattern of anti-lymphocytic reactivity, mostly against B lymphocytes. Human lymphocytic antigens (HLA) analysis of donors' lymphocytes suggested that activity of LCA-positive RA sera is HLA directed in 60% of cytotoxic sera. The anti-HLA antibodies found were not autoreactive and were not restricted to a particular class I or class II antigen. Relating the presence of LCAs to selective clinical features revealed that LCAs are inversely associated with the presence of an erosive disease (P <0.01) and with the patients' HLA-DQw1 (P <0.01). These findings suggest that LCAs in Israeli patients with RA are very common, multispecific and may have a protective role not mediated through interaction with self-HLA antigens.
Antilymphocyte Serum↗
[Macroscopic evaluation of placental from ecologically-challenged area (Plock) -- Part II].
It was analysed selected macroscopic features of 226 placentas from normal pregnancies. The 146 of them was obtained from phenol's polluted area (Pøock) and from control group (Kutno). The exceeding of physiologic norm of phenol's excretion in 24-hours urine from pregnant women was the measure of pollution.
Chemical Industry↗
[Frequency and current clinical diversity of cerebral cortical dysgenesis].
OBJECTIVE: The extended use of MRI has increased the number of patients diagnosed of cortical dysgenesis and has changed the clinical spectrum usually associated with this disorder. The aim of this study was to know the frequency and clinical variety of cortical dysgenesis in our current patient population. PATIENTS AND METHODS: All patients with dysgenesis of the neocortex or of the hippocampus, according to radiological or pathological features, were selected from the total number of patients attended during 1996 at an outpatient hospital-based neuropediatric clinic. Malformations of cerebellar cortex and neurocutaneous syndrome were excluded. RESULTS: Twenty-one patients (1.3% of all patients attended at the clinic) studied by MRI showed polymicrogyria (43%) which was of perisilvian localization in three patients, heterotopias (33%), dysplasia of the hippocampus (24%), agyria-pachygria (14%) and hemimegaencephalia (5%). Three patients underwent surgical interventions. Epilepsy was present in 90%, mental retardation in 68%, cerebral palsy 47%, infantile spasms 40%, microcephally 25%, autism 10%, hyperkinesis 5% and learning disabilities in 33% of those school age children free of mental retardation. CONCLUSIONS: The actual prevalence of cortical dysgenesis at our clinic is similar to that of neurodevelopmental impairments following birth-asphyxia (1.2%), amounting to two thirds of those following prematurity and to half of those following a brain injury of late prenatal onset. Except for the almost constant presence of epilepsy, especially infantile spasms, clinical symptomatology is diverse and occurs in a similar percentages in brain lesions acquired during labour or during late pregnancy. Hyperkinesis and autism have a similar prevalence to that seen in the total number of patients attended at the clinic during 1996.
Cerebral Cortex↗
Promoting safe and comfortable driving for elders.
Americans are life-long drivers. It is imperative that aging drivers remain on the road safely. This chapter addresses one strategy for achieving this end, namely the utilization of low-tech vehicle modifications for addressing challenges with driving due to functional deficits that normally occur with aging. It focuses primarily on the selection of useful features to be demonstrated in a video intervention in a research project to assess whether watching the video would increase elders' awareness of and likelihood of using the features. The features were chosen with the assistance of a panel of experts in transportation, aging, rehabilitation, and related fields plus a focus group of older drivers. Selecting the features, developing survey instruments, and producing the video constitute Phase I of the study. Phase II investigates whether watching a video would increase older drivers' awareness of such features and motivate them to use any of them. This chapter also includes an overview of Phase II and some comments with respect to high-tech features and the future of automobile travel.
Accident Prevention↗
Neural networks for detection and classification of walking pattern changes due to ageing.
With age, gait functions reflected in the walking patterns degenerate and threaten the balance control mechanisms of the locomotor system. The aim of this paper is to explore applications of artificial neural networks for automated recognition of gait changes due to ageing from their respective gait-pattern characteristics. The ability of such discrimination has many advantages including the identification of at-risk or faulty gait. Various gait features (e.g., temporal-spatial, foot-ground reaction forces and lower limb joint angular data) were extracted from 12 young and 12 elderly participants during normal walking and these were utilized for training and testing on three neural network algorithms (Standard Backpropagation: Scaled Conjugate Gradient; and Backpropagation with Bayesian Regularization, BR). Receiver operating characteristics plots, sensitivity and specificity results as well as accuracy rates were used to evaluate performance of the three classifiers. Cross-validation test results indicate a maximum generalization performance of 83.3% in the recognition of the young and elderly gait patterns. Out of the three neural network algorithms, BR performed superiorly in the test results with best sensitivity, selectivity and detection rates. With the help of a feature selection technique, the maximum classification accuracy of the BR attained 100%, when trained with a small subset of selected gait features. The results of this study demonstrate the capability of neural networks in the detection of gait changes with ageing and their potentials for future applications as gait diagnostics.
Adult↗
The clinical value of computerized axial tomography in patients without focal neurological features.
74 randomly selected patients with non-focal cerebral symptoms and a normal neurologic examination were referred from neurologic departments to CT scan of the brain. 29 patients had generalised epilepsy of long duration. In 26 patients (90%) with epilepsy the CT scan was normal. 2 patients (7%) had cerebral atrophy, 1 (3%) showed porencephaly (?) 41 (91%) of the patients without epileptic features had a normal CT scan. 4 (9%) presented cerebral atrophy. In this survey, CT scanning did not contribute to a focal diagnosis in patients with diffuse cerebral features.
Adolescent↗
[Typological features of behavior and memory in Norway rats selected for absence of aggression toward a man].
Features of behavior and retrieval of passive conditioned avoidance on a new and forgotten stimuli were compared in Wistar rats and Norway rats bred for the absence of aggression toward a man. As distinct from white rats, grey rats were characterized by low anxiety and high locomotor exploratory activity in the elevated plus maze and dark-light chamber. Norway rats demonstrated better avoidance performance with active defensive behavioral strategy than Wistar rats. Latent inhibition during conditioning with a previously forgotten situational stimulus was the same in both rat strains. The results are discussed in terms of the use of grey rats as a model for an in-depth analysis of the mechanisms of memory optimization.
Aggression↗
A multi-feature and multi-channel univariate selection process for seizure prediction.
OBJECTIVE: To develop a prospective method for optimizing seizure prediction, given an array of implanted electrodes and a set of candidate quantitative features computed at each contact location. METHODS: The method employs a genetic-based selection process, and then tunes a probabilistic neural network classifier to predict seizures within a 10 min prediction horizon. Initial seizure and interictal data were used for training, and the remaining IEEG data were used for testing. The method continues to train and learn over time. RESULTS: Validation of these results over two workshop patients demonstrated a sensitivity of 100%, and 1.1 false positives per hour for Patient E, using a 2.4s block predictor, and a failure of the method on Patient B. CONCLUSIONS: This study demonstrates a prospective, exploratory implementation of a seizure prediction method designed to adapt to individual patients with a wide variety of pre-ictal patterns, implanted electrodes and seizure types. Its current performance is limited likely by the small number of input channels and quantitative features employed in this study, and segmentation of the data set into training and testing sets rather than using all continuous data available. SIGNIFICANCE: This technique theoretically has the potential to address the challenge presented by the heterogeneity of EEG patterns seen in medication-resistant epilepsy. A more comprehensive implementation utilizing all electrode sites, a broader feature library, and automated multi-feature fusion will be required to fully judge the method's potential for predicting seizures.
Algorithms↗
Learning to attend: modeling the shaping of selectivity in infero-temporal cortex in a categorization task.
Recent experiments on behaving monkeys have shown that learning a visual categorization task makes the neurons in infero-temporal cortex (ITC) more selective to the task-relevant features of the stimuli (Sigala and Logothetis in Nature 415 318-320, 2002). We hypothesize that such a selectivity modulation emerges from the interaction between ITC and other cortical area, presumably the prefrontal cortex (PFC), where the previously learned stimulus categories are encoded. We propose a biologically inspired model of excitatory and inhibitory spiking neurons with plastic synapses, modified according to a reward based Hebbian learning rule, to explain the experimental results and test the validity of our hypothesis. We assume that the ITC neurons, receiving feature selective inputs, form stronger connections with the category specific neurons to which they are consistently associated in rewarded trials. After learning, the top-down influence of PFC neurons enhances the selectivity of the ITC neurons encoding the behaviorally relevant features of the stimuli, as observed in the experiments. We conclude that the perceptual representation in visual areas like ITC can be strongly affected by the interaction with other areas which are devoted to higher cognitive functions.
Algorithms↗
Multiple structural features of steroids mediate subtype-selective effects on human alpha4beta3delta GABAA receptors.
Neurosteroids have been shown to mediate some of their physiological effects via a modulatory site on type A inhibitory gamma-aminobutyric acid (GABAA) receptors. In particular, recent evidence has implicated selective potentiation of the delta subunit of GABAA receptors as an important mediator of in vitro and in vivo neurosteroid activity. However, this has been demonstrated for only a very small number of steroids, so both the generality of this finding, and the structural features of steroids which mediate functional delta-selectivity, are unclear. We have used a potentiometric assay based on fluorescence resonance energy transfer to measure GABA-activated responses in L(tk-) cells stably transfected with human GABAA receptor alpha4beta3delta and alpha4beta3gamma2 receptor subtypes. A set of 28 steroids were evaluated on these subtypes to characterise their functional potency and efficacy in modulating GABA responses. For most compounds there was a clear separation of their efficacy profiles between the receptor subtypes, with a substantially larger maximal response at the alpha4beta3delta receptor. 5beta-Pregnan-3beta-ol-20-one, 5beta-pregnane-3alpha,20beta-diol and 5beta-pregnane-3alpha,17alpha-diol-11,20-dione showed particularly high efficacy for alpha4beta3delta. No compounds were identified that simply inhibited responses at delta-containing receptors. However, 5beta-pregnane-3alpha,17alpha,20beta-triol, prednisolone 21-acetate, 4-pregnene-17alpha,20alpha-diol-3-one-20-acetate, 4-pregnen-20alpha-ol-3-one, and 5beta-pregnane-3alpha,17alpha,21-triol-20-one inhibited, though did not abolish, GABA responses at the alpha4beta3gamma2 subtype, while evoking modest-amplitude potentiation of alpha4beta3delta responses. Molecular modelling on this compound series using principal components analysis indicates that several structural features of steroids underlie their relative functional selectivity for potentiation of delta-containing GABAA receptors.
Animals↗
Classification of dopamine antagonists using functional feature hypothesis and topological descriptors.
The designing of selective dopamine antagonists for their own subreceptors can be useful in individual therapy of various neuropsychiatric disorders. Three-dimensional pharmacophore hypothesis and two-dimensional topological descriptors were used to investigate and compare different classes of dopamine antagonists. The structurally diverse D(3) and D(4) antagonists above preclinical trials were selected to map common structural features of highly selective and efficacious antagonists. The generated pharmacophore hypotheses were successfully employed as discriminative probe for database screening. To filter out the false positive from screening hits, the classification models by two-dimensional topological descriptors were built. Molconn-Z and BCUT topological descriptors were employed to develop a classification model for 1328 dopamine antagonists from MDDR database. The soft independent modeling of class analogy and artificial neural network, two supervised classification techniques, successfully classified D(1), D(3), and D(4) antagonists at the average of 80% rates into their own active classes. The mean classification rates for D(2) antagonists were obtained to 60% due to insufficient selective D(2) antagonists. In this paper, we report the validity of our models generated using functional feature hypotheses and topological descriptors. The combining both of classification using functional feature hypotheses and topological descriptors would be a useful tool to predict selective antagonists.
Algorithms↗
Effects of truncal or highly selective vagotomy on the electron microscopic feature of the rabbit pancreas.
PURPOSE: To perform a comparative study of two types of vagotomy: trunctal vagotomy (TV) and highly selective vagotomy (HSV) effects on pancreatic morphology assessed with light microscope and ultrastructural changes assessed with electron microscope in rabbits 30, 90 and 180 days after the vagotomy. MATERIAL AND METHODS: The experiments were carried out on 89 male Popielno white rabbits, aged 4-6 months, 2.5 to 3.0 kg of body weight. On the 30th, 90th and 180th day after the vagotomy, rabbits were sacrificed and the pancreases were taken for the light and electron microscopic evaluation. RESULTS: The regressive changes coexisting with adaptive like renewal of epithelial cells and mild interstitial fibrosis resulting from vagotomy were more pronounced in the early post-operative period and tended to normalize in the later post-operative one. All the changes seen in post-operative period were more prominent after TV than after HSV. CONCLUSIONS: Both truncal and highly selective vagotomy affects evidently the morphology and ultrastructure of the pancreas in rabbits however the changes after the first procedure were more advanced than after the latter one. The intensity of the changes is highest early after these operations and tend to normalize in the later post-operative period.
Animals↗
Benign and malignant ovarian masses: selection of the most discriminating gray-scale and Doppler sonographic features.
PURPOSE: To determine the gray-scale and Doppler sonographic features that best enable discrimination between malignant and benign ovarian masses and develop a scoring system for accurate diagnosis with these features. MATERIALS AND METHODS: Gray-scale and Doppler sonographic features of 211 adnexal masses were correlated with the final diagnosis; the most discriminating features for malignancy were selected with stepwise logistic regression. RESULTS: Twenty-eight masses were malignant and 183 benign. All masses with a markedly hyperechoic solid component or no solid component were benign. For masses with a nonhyperechoic solid component, additional features that allowed statistically significant discrimination of benignity from malignancy were, in decreasing order of importance, (a) location of flow at conventional color Doppler imaging, (b) amount of free intraperitoneal fluid, and (c) presence and thickness of septations. A scoring formula that made use of values based on the logistic regression equation had an area under the receiver operating characteristic curve of 0.98 +/- 0.01. The cutoff score with the highest accuracy had a sensitivity of 93% and specificity of 93%. CONCLUSION: A solid component is the most statistically significant predictor of a malignant ovarian mass. A multiparameter scoring system that uses three gray-scale and one Doppler feature, developed by means of stepwise logistic regression, has high sensitivity and specificity for predicting malignancy.
Adolescent↗
GFREG: a computer program for maximum likelihood regression using the Generalized F distribution.
A FORTRAN program is described for maximum likelihood estimation within the Generalized F family of distributions. It can be used to estimate regression parameters in a log-linear model for censored survival times with covariates, for which the error distribution may have a great variety of shapes, including most distributions of current use in biostatistics. The optimization is performed by an algorithm based on the generalized reduced gradient method. A stepwise variable search algorithm for covariate selection is included in the program. Output features include: model selection criteria, standard errors of parameter estimates, quantile and survival rates with their standard errors, residuals and several plots. An example based on data from Princess Margaret Hospital, Toronto, is discussed to illustrate the program's capabilities.
Biometry↗
ERP time course of perceptual and post-perceptual mechanisms of spatial selection.
Event-related potentials (ERPs) were recorded from volunteers performing a task requiring simple judgements about the spatial location of a single target that could appear with equal probability to the left or right of fixation. A robust finding in the ERP literature is a dichotomy between attentional selection for spatial and non-spatial features. Visual spatial selection is manifest as a modulation of early components (P1, N1) that reveal exogenous processes, while non-spatial selection is revealed by the presence of longer latency endogenous components (N2). We present an analysis of several conditions that require different degrees of visual analysis to confirm the location of the single target, and show that spatial selection can be manifest at early (N1) or later (N2) stages. Observers identified the location of targets that were more salient (2D line drawings with abrupt onset) or less salient (2D line drawings without abrupt onset or 3D objects embedded in random-dot stereograms). We examined differences in amplitude, latency, and topography of early ERP components (P1, N1, P2, N2), and compared responses measured over the left and right hemispheres in response to left and right targets. The results support the hypothesis that the processes involved in spatial selection can be manifest at early or late stages, dependent on the quality of the incoming data. Moreover, the iterative process by which the percept is established benefits from a change in the visual input that is specific to the target.
Analysis of Variance↗