Computer analyses of lymphocytes in transformation. A methodologic study.
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Computers↗
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[Computer-assisted diagnosis].
Numerous models of computer-aided diagnosis have been developed. However, only a few are used in the clinical routine. The methodology of computer-aided diagnosis is described briefly in this paper and a survey of clinical applications is given. Standards for evaluating these models are proposed and illustrated by examples. The inadequate assessment of most diagnostic systems is one of the main reasons for their limited clinical use. New methodological and technical developments will lead to more clinical applications, if the systems are evaluated adequately.
Diagnosis, Computer-Assisted↗
An integrated impact assessment and weighting methodology: evaluation of the environmental consequences of computer display technology substitution.
Computer display technology is currently in a state of transition, as the traditional technology of cathode ray tubes is being replaced by liquid crystal display flat-panel technology. Technology substitution and process innovation require the evaluation of the trade-offs among environmental impact, cost, and engineering performance attributes. General impact assessment methodologies, decision analysis and management tools, and optimization methods commonly used in engineering cannot efficiently address the issues needed for such evaluation. The conventional Life Cycle Assessment (LCA) process often generates results that can be subject to multiple interpretations, although the advantages of the LCA concept and framework obtain wide recognition. In the present work, the LCA concept is integrated with Quality Function Deployment (QFD), a popular industrial quality management tool, which is used as the framework for the development of our integrated model. The problem of weighting is addressed by using pairwise comparison of stakeholder preferences. Thus, this paper presents a new integrated analytical approach, Integrated Industrial Ecology Function Deployment (I2-EFD), to assess the environmental behavior of alternative technologies in correlation with their performance and economic characteristics. Computer display technology is used as the case study to further develop our methodology through the modification and integration of various quality management tools (e.g., process mapping, prioritization matrix) and statistical methods (e.g., multi-attribute analysis, cluster analysis). Life cycle thinking provides the foundation for our methodology, as we utilize a published LCA report, which stopped at the characterization step, as our starting point. Further, we evaluate the validity and feasibility of our methodology by considering uncertainty and conducting sensitivity analysis.
Computer Terminals↗
Computer-assisted visualization of the rat epididymis: a methodological study based on paraffin sections autometallographically stained for zinc ions.
A concept for the computer-assisted visualization of tubular organs is presented. Unmarked histological zinc-stained serial sections from the epididymis of the Wistar rat were aligned to demonstrate the concept. Virtual images were made through the aligned sections and served as controls for the alignment process. Animation of the serial sections and the virtual images revealed new information about the structure of the organ under investigation. The analysis was used to upgrade the anatomical knowledge of rat epididymis by describing how the epididymal duct runs through the structure. The proximal parts of the epididymis contain large communicating septa of connective tissue dividing the caput and the upper part of the corpus epididymidis into segments. The tortuousness was high in the caput with many turns within a small area of the epididymis, whereas longer loops were found in the lower part of the corpus and cauda epididymidis. The tube of the vas deferens was found to become an integrated part of the ductal system in the cauda epididymidis, although it was histologically easy to distinguish from the epididymal duct. The total number of cross-sections of the ductus epididymidis in the 2254, 15-microm-thick, tissue sections analysed was 104700, giving a minimum length of the ductal system of 1.5 m.
Animals↗
[Computed tomography exploration of the normal lumbar spine: methodology and anatomical appearances].
A new method for exploring the lumbar spine by means of serial computed tomography sections is proposed, radio-anatomical appearances of the normal lumbar canal and its contents being described and illustrated.
Humans↗
Computer intuition: guiding scientific research in imaging and oral implantology.
As the costs associated with clinical research and new drug development increase, it is incumbent upon us to develop alternative research methodologies. A new Computer Intuition (CI) program identifies literature-based evidence with the potential to generate a hypothesis that is most likely to be clinically confirmed regarding the cause of a disease or the questions being posed. The objective of this study was to demonstrate whether computer intuition can be used to guide scientific research in solving important biomedical questions. The establishment of CI as an alternative research methodology has the potential to accelerate the translation of basic science findings into clinical practice. The specific aim of this study was to develop a CI-driven hypothesis related to the controversial issue debating which radiographic imaging technology is most suitable for diagnostic purposes prior to the placement of oral implants. This hypothesis was then compared, in retrospect, with a known opinion established following a recent literature review on this issue. In his review of the literature, Frederiksen (1995) suggests that multiplanar reformatted computed tomography (CT) is the diagnostic imaging modality of choice prior to implant placement. To compare the CI hypothesis with Frederiksen's (1995) opinion, we subjected 34 relevant papers to CI analysis. The output consisted of clusters of important statements, phrases, and thought processes from the given dataset rated with the greatest potential to generate testable hypotheses. Both CI's output and Frederiksen (1995) indicated that CT scanning is the diagnostic imaging modality of choice prior to implant placement. Although the ultimate utility of CI is dependent on the successful testing of its derived hypothesis, this preliminary retrospective study suggests that CI might be useful in guiding scientific research.
Algorithms↗
Computing mating bull fertility from DHI nonreturn data.
Animal model methodology was used to compute yearly measures of relative fertility of Holstein AI mating bulls based upon 70-d nonreturn of first breedings as reported to U.S. DHIA from 1988 through 1997. Estimated Relative Conception Rates (ERCR) were computed for bulls with a minimum of 50 first breedings in a single year using variance ratios 45.5 for mating bull, 45.5 for animal genetic effects, and 31 for permanent environment. The model assumed repeatability across lactations of 0.05 and included fixed effects of herd-year-month bred and classes of parity, early lactation energy-corrected milk and days open when bred. Estimates of fertility were greater for breedings to cows that were young, had low early lactation production, and were in late stages of lactation. ERCR were expressed as difference in nonreturn from the average AI mating bull of herdmates. Values ranged from -18 to +13. For ERCR computed from a minimum of 1000 breedings, 90% were within four units of zero. Early ERCR computed from a few breedings in a single year were tested for ability to predict later ERCR computed from a minimum of 1000 different breedings. Early ERCR computed from 300 or more matings accurately predicted later independent ERCR. For yearly estimates each based upon a minimum of 1000 breedings, 8% changed more than three units, and 4% declined more than three units. Correlations between ERCR and predicted transmitting abilities protein and type production index were significant but accounted for little variance. Correlations between ERCR and other traits were not significant.
Age Factors↗
[Computer tomography in cardiology. 1. Methods].
The authors discuss the methodology of the computer-aided tomography of the heart which is to include dynamic scanning with, if indicated, synchronous ECG paralleled with the intravenous bolus administration of the contrast medium. The synchronization with ECG makes it possible to obtain a computer-aided tomographic image of the heart at any phase of the cardiac cycle. Computer-aided tomography was performed in 306 patients with various forms of heart disease. Five levels of scanning can be identified under normal conditions which present all structural elements of the heart.
Aortic Aneurysm↗
Arterial embolization in the treatment of severe blunt hepatic trauma.
BACKGROUND/AIMS: The Authors stress the role of arterial embolization in the treatment of severe blunt hepatic trauma, with stable hemodynamic conditions, but with continuous bleeding, demonstrated by computed tomography scan. METHODOLOGY: All patients with hepatic blunt trauma were evaluated with hemodynamic and radiological follow-up. When computed tomography scan showed continuous bleeding, arterial embolization was performed. RESULTS: Arterial embolization was performed on 9 patients, 8 cases successfully. Only one patient required surgical treatment. CONCLUSIONS: Our results show that arterial embolization is useful and effective in the treatment of severe blunt hepatic trauma when, in spite of stable hemodynamic state, computed tomography scan shows persistent bleeding.
Adult↗
Automated diagnosis of data-model conflicts using metadata.
The authors describe a methodology for helping computational biologists diagnose discrepancies they encounter between experimental data and the predictions of scientific models. The authors call these discrepancies data-model conflicts. They have built a prototype system to help scientists resolve these conflicts in a more systematic, evidence-based manner. In computational biology, data-model conflicts are the result of complex computations in which data and models are transformed and evaluated. Increasingly, the data, models, and tools employed in these computations come from diverse and distributed resources, contributing to a widening gap between the scientist and the original context in which these resources were produced. This contextual rift can contribute to the misuse of scientific data or tools and amplifies the problem of diagnosing data-model conflicts. The authors' hypothesis is that systematic collection of metadata about a computational process can help bridge the contextual rift and provide information for supporting automated diagnosis of these conflicts. The methodology involves three major steps. First, the authors decompose the data-model evaluation process into abstract functional components. Next, they use this process decomposition to enumerate the possible causes of the data-model conflict and direct the acquisition of diagnostically relevant metadata. Finally, they use evidence statically and dynamically generated from the metadata collected to identify the most likely causes of the given conflict. They describe how these methods are implemented in a knowledge-based system called GRENDEL and show how GRENDEL can be used to help diagnose conflicts between experimental data and computationally built structural models of the 30S ribosomal subunit.
Algorithms↗
Calculation of absolute protein-ligand binding free energy from computer simulations.
A general methodology for calculating the equilibrium binding constant of a flexible ligand to a protein receptor is formulated on the basis of potentials of mean force. The overall process is decomposed into several stages that can be computed separately: the free ligand in the bulk is first restrained into the conformation it adopts in the bound state, position, and orientation by applying biasing potentials, then it is translated into the binding site, where it is released completely. The conformational restraining potential is based on the root-mean-square deviation of the peptide coordinates relative to its average conformation in the bound complex. Free energy contributions from each stage are calculated by means of free energy perturbation potential of mean force techniques by using appropriate order parameters. The present approach avoids the need to decouple the ligand from its surrounding (bulk solvent and receptor protein) as is traditionally performed in the double-decoupling scheme. It is believed that the present formulation will be particularly useful when the solvation free energy of the ligand is very large. As an application, the equilibrium binding constant of the phosphotyrosine peptide pYEEI to the Src homology 2 domain of human Lck has been calculated. The results are in good agreement with experimental values.
Binding Sites↗
[Computed tomography in dental implantation. Technical and methodological aspects].
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Dental Implantation, Endosseous↗
Metrizamide computed tomography cisternography: pediatric applications.
The methodology and clinical use of metrizamide (Amipaque) computed tomography (CT) cisternography are described as applied in the cases of 22 children with morphologic and physiologic abnormalities affecting the cranial portion portion of the central nervous system. In contrast to pneumoencephalography, CT cisternography affords equivalent or superior visualization of the basal cranal subarachnoid spaces with simpler technique and low morbidity. Intrathecal metrizamide enchancement in children causes a very low incidence of side effects.
Adenoma, Chromophobe↗
An overview of computer algorithms for deconvolution-based assessment of in vivo neuroendocrine secretory events.
The availability of increasingly efficient computational systems has made feasible the otherwise burdensome analysis of complex neurobiological data, such as in vivo neuroendocrine glandular secretory activity. Neuroendocrine data sets are typically sparse, noisy and generated by combined processes (such as secretion and metabolic clearance) operating simultaneously over both short and long time spans. The concept of a convolution integral to describe the impact of two or more processes acting jointly has offered an informative mathematical construct with which to dissect (deconvolve) specific quantitative features of in vivo neuroendocrine phenomena. Appropriate computer-based deconvolution algorithms are capable of solving families of 100-300 simultaneous integral equations for a large number of secretion and/or clearance parameters of interest. For example, one application of computer technology allows investigators to deconvolve the number, amplitude and duration of statistically significant underlying secretory episodes of algebraically specifiable waveform and simultaneously estimate subject- and condition-specific neurohormone metabolic clearance rates using all observed data and their experimental variances considered simultaneously. Here, we will provide a definition of selected deconvolution techniques, review their conceptual basis, illustrate their applicability to biological data and discuss new perspectives in the arena of computer-based deconvolution methodologies for evaluating complex biological events.
Algorithms↗
Computed tomography-guided anterior approach to the superior hypogastric plexus for noncancer pelvic pain: a report of two cases.
The objective of this study was to evaluate the possibility and describe the methodology of a computed tomography-guided anterior approach to superior hypogastric plexus block for noncancer pain. A computed tomography-guided anterior approach to the superior hypogastric plexus was used in 2 patients with pelvic pain and anatomic disturbance of the lumbar spine, which was a contraindication to the conventional dorsal approach. The first case was a 43-year-old patient suffering from burning pain of the urethra. Pain relief using analgesics and antidepressants was insufficient. The posterior approach was excluded due to coexisting irritation of the L5 nerve root. The second case was a 68-year-old man suffering from chronic burning and itching pain of the urethra and glans penis. Conservative therapy (anti-inflammatory drugs, tramadol, spasmolytics) failed to provide satisfactory pain relief. The posterior approach was contraindicated because of laterally prominent L5 vertebral body osteophytes. Both patients received a prognostic block to the superior hypogastric plexus via the anterior approach guided by computed tomography. Visual analog scale scores prior to the block were 6 to 7 and 5 to 6, respectively. The visual analog scale scores 24 hours after the block were 1 and 0, respectively. The second patient received a permanent neurolytic block via the anterior approach to provide long-term pain relief. In conclusion, the authors describe the computed tomography-guided anterior approach to the superior hypogastric plexus for chronic pelvic pain. The technique is simple to perform, and the analgesic effect is satisfactory. More extensive studies are necessary to evaluate the safety of this approach.
Adult↗
Computer aided vertebral visualization and analysis: a methodology using the sand rat, a small animal model of disc degeneration.
BACKGROUND: The purpose of this study is to present an automated system that analyzes digitized x-ray images of small animal spines identifying the effects of disc degeneration. The age-related disc and spine degeneration that occurs in the sand rat (Psammomys obesus) has previously been documented radiologically; selected representative radiographs with age-related changes were used here to develop computer-assisted vertebral visualization/analysis techniques. Techniques presented here have the potential to produce quantitative algorithms that create more accurate and informative measurements in a time efficient manner. METHODS: Signal and image processing techniques were applied to digitized spine x-ray images the spine was segmented, and orientation and curvature determined. The image was segmented based on orientation changes of the spine; edge detection was performed to define vertebral boundaries. Once vertebrae were identified, a number of measures were introduced and calculated to retrieve information on the vertebral separation/orientation and sclerosis. RESULTS: A method is described which produces computer-generated quantitative measurements of vertebrae and disc spaces. Six sand rat spine radiographs illustrate applications of this technique. Results showed that this method can successfully automate calculation and analysis of vertebral length, vertebral spacing, vertebral angle, and can score sclerosis. Techniques also provide quantitative means to explore the relation between age and vertebral shape. CONCLUSIONS: This method provides a computationally efficient system to analyze spinal changes during aging. Techniques can be used to automate the quantitative processing of vertebral radiographic images and may be applicable to human and other animal radiologic models of the aging/degenerating spine.
Aging↗
Methodology and validity in the construction of computational models of cognitive deficits following brain damage.
Over recent years, neural network models of several cognitive neuropsychological disorders have been developed. These include word recognition difficulties, face recognition difficulties, attentional deficits, visual processing impairments, semantic deficits, and aphasia. These models are useful in various ways. Firstly, they require detailed specifications of theories, and can focus attention on critical assumptions. Secondly, they can query alternative theories, and provide predictions which can be verified by testing patients. In this paper, issues relating both to the methodology and validity of attempts to model cognitive deficits using neural networks will be discussed, providing examples from several studies. Issues discussed will include the requirement for models to perform normally prior to damage, and to show potential effects of rehabilitation or partial recovery following damage. A single model should be able to incorporate multiple symptoms of a deficit and ideally also multiple syndromes when different lesions are introduced. The model must also be able to handle variability between patients with the same syndrome, and even with the same patient at different test sessions.
Brain Injuries↗
[Kidney spiral CT. Indication, method, results].
The introduction on spiral computed tomography (spiral CT) has vastly enriched the methodological diversity of computer-tomographic scans. It allows for the recording of different perfusion or excretion stages of the kidney parenchyma of the urine draining paths by carrying out long-distance, phase-identical multiple examinations of the retroperitoneum. The description of the findings which are characterized by their local and contrasts behavior is possible. The following report describes the indications and technological process of kidney spiral CT using kidney-typical intravenous contrast media. Special emphasis is put on the advantages and limits of multiple phase spiral CT. Decisive preconditions are: 1. specific clinical query, 2. selection of the corresponding phase contrasts of the kidneys and uretra or bladder, 3. exact technical and temporal adjustment of the acquisition parameters. Scanning times are in the range of seconds. The overall examination can be carried out quick and without any major strain on the part of the patient. A sound proof and a general differentiation of focal kidney lesions can be derived from the acquired data. This is also true for kidneys and ureters findings. Bladder findings can be localized and differentiated according to stage. More than two "spiral acquisitions" should be carried out with re-straint taking exposure to radiation into account. Due to the sound registration of focal lesions, its capability of reproduction and its short-time examination, the spiral CT of the kidneys can be said to be the most effective current scanning method of the retroperitoneum following clinical examinations and sonography.
Female↗