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At least 217 records · Page 12Linked to original sources
PubMed1998

Implementation of a fuzzy prototype-based machine learning method to predict myocardial infarction from coronary angiography.

Formal knowledge on the predictive value of morphological angiographic factors is lacking to estimate the risk of myocardial infarction. This article presents a computer system for predicting the incidence of myocardial infarction from angiographic morphological descriptions of coronary lesions. The system includes two phases. The learning phase consists in extracting from a large database of described stenoses two classes represented by one or several fuzzy prototypes. One class corresponds to stenoses leading to infarction and the other to stenoses not leading to that event. The evaluation phase consists in classifying a stenosis according to its morphological characteristics in one of these two classes. The learning method is based on a fuzzy supervised Machine Learning algorithm that combines some aspects of the K-nearest neighbours clustering approach with a defined measure of similarity, and a prototype induction function from the most similar stenoses, taking into account their degree of typicality. The current results of the evaluation phase to correctly predicted X% stenoses for their risk of myocardial infarction. This article emphasizes the feasibility of the approach, however, the learning phase relies on some heuristics that should be validated to get a formal evaluation of the system.

Artificial Intelligence↗
PubMed1999

Selective laser sintering: application of a rapid prototyping method in craniomaxillofacial reconstructive surgery.

Advances in technology have benefited the medical world in many ways and a new generation of computed tomography (CT) scanners and three-dimensional (3-D) model making rapid prototyping systems (RPS) have taken craniofacial surgical planning and management to new heights. With the development of new rapid prototyping systems and the improvements in CT scan technology, such as the helical scanner, biomedical modelling has improved considerably and accurate 3-D models can now be fabricated to allow surgeons to visualise and physically handle a 3-D model on which simulation surgery can be performed. The principle behind this technology is to first acquire digital data (CT scan data) which is then imported to the RPS to fabricate fine layers or cuts of the model which are gradually built up to form the 3-D models. Either liquid resin or nylon powder or special paper may be used to make these models using the various RPS available today. Selective laser sintering (SLS), which employs a CO2 laser beam to solidify special nylon powder and build up the model in layers is described in this case report, where a 23-year old Chinese female with panfacial fracture and a skull defect benefited from SLS biomodelling in the preoperative workup.

Accidents, Traffic↗
PubMed1992

DentLE. The Dental Learning Environment: a prototype demonstration.

DentLE, the Dental Learning Environment is a hypermedia software system being prototyped as part of a research and development project at the State University of New York at Buffalo School of Dental Medicine. The design seeks to reach beyond single discipline software or cases, and integrate a range of patient problems within a comprehensive dental knowledge base. The approach is to use computer and hypermedia technology to weave together the disciplines of dentistry so that learning occurs in relation to patients, as they appear in the real world. The DentLE system prototype allows the learner to explore information in all the disciplines related to patient problems, as well as other information including "blind alleys" and results of curiosity.

Computer-Assisted Instruction↗
PubMed1991

[Hepatitis C virus: sequence homology of a European isolate and divergence from the prototype].

The polymerase chain reaction (PCR) detected specific hepatitis C viral (HCV) RNA sequences in liver biopsies from two patients with chronic hepatitis, in the tissue of a liver implantate, in plasma from four chronic non-A, non-B hepatitis (NANBH) patients and, for the first time, in an infectious anti-D-immunoglobulin preparation. A comparison of the viral sequences coding for a region for the nonstructural NS3 protein from the liver tissues revealed only a very small degree of sequence divergence on the cDNA as well as on the amino acid level (between 0 and 5%). The sequence similarities of the RNA isolated from plasma of the four chronic NANBH patients and the anti-D-immunoglobulin preparation were partly somewhat lower but altogether also high (between 90 and 100%). In contrast, all eight cDNA and amino acid sequences exhibited a significantly higher degree of divergence in comparison with the HCV prototype sequence (between 29 and 32%) than among themselves (between 0 and 10%). This unexpected high sequence similarity of the eight European isolates and their low homology to the Northamerican prototype sequence is indicative for the existence of different types of HCV. This will be important not only for epidemiological studies but also for the development of effective diagnostic procedures and vaccines. Concerning the pathogenesis of NANBH, a double infection or a helper mechanism has to be considered: in addition to the C virus, sequences of an other virus particle were found in the infectious IgG preparation as well as in the liver biopsies.

Amino Acid Sequence↗
PubMed1991

CD-ROM prototype applications within the Department of Veterans Affairs.

The Department of Veterans Affairs (VA) has been actively involved in examining the benefits of Compact Disc Read Only Memory (CD-ROM) to its operations. Approximately twenty VA titles either have been produced or are scheduled for production by Summer of 1991. Both textual and database CDs have been prototyped. Several of the CDs have been integrated directly into the VA's MUMPS-based hospital information systems. Titles which contain patient information employ the Data Encryption Standard (DES) for sensitive information. A related project involves the installation of a system which allows common VDTs on the hospital system to access commercial CDs such as MEDLINE, PDR, and CCIS. The prototypes have been successful and very favorably received by users.

CD-ROM↗
PubMed1991

AI/Consult: a prototype directed history system based upon the AI/Rheum knowledge base.

An expert system is designed which uses the AI/Rheum knowledge base as the basis for a directed workup system for rheumatological disorders. A Turbo Pascal prototype is demonstrated which, unlike AI/Rheum, permits entry by the clinician of a patient's chief complaint(s) and subsequently develops a dynamic differential diagnosis for this limited set of findings. The system restricts its line of questioning to those pertinent in order to rule in or rule out items on this dynamic differential diagnosis, and, unlike AI/Rheum, it provides immediate notification to the user when a critical mass of information has been entered in order to meet a diagnosis at one of the AI/Rheum criteria table's three levels of diagnosis (possible, probable, definite). Thus the system allows for a more rapid, focused decision making approach than does AI/Consult, while it follows the trend established by QMR in that it abandons the Greek Oracle problem solving approach and instead adopts a physician-assisted hypothesis investigation approach. The system is currently a prototype, without AI/Rheum's page oriented and mouse driven interface, and thus the total user interaction time may be longer than with AI/Rheum even though fewer user interactions (responses) are required. Plans for future development include optimization of the knowledge base to allow for more efficient, problem oriented questioning and modification of the knowledge base compiler in order to dynamically rule out diseases through the addition of three new levels of diagnosis in the knowledge base criteria tables.

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

Emergence of highly pathogenic virus during selective chicken passage of the prototype mildly pathogenic chicken/Pennsylvania/83 (H5N2) influenza virus.

The prototype mildly pathogenic A/chicken/Pennsylvania/21525/83 (H5N2) avian influenza virus, which was isolated more than 5 months before the emergence of highly pathogenic virus in the major 1983 Pennsylvania outbreak, was examined for the presence of minority subpopulations of highly pathogenic virus. Selective serial passage of the parental mildly pathogenic virus in leghorn hens did not lead to recovery of highly pathogenic virus. However, several highly pathogenic reisolates were recovered from hens inoculated with either of two mildly pathogenic virus clones selected for their ability to efficiently produce plaques in trypsin-free chicken embryo fibroblasts. Unlike the parental virus, these reisolates caused high mortality in chickens and produced postmortem lesions typical of highly pathogenic avian influenza. Electrophoretic mobilities of the hemagglutinin glycoproteins of the highly pathogenic derivatives resembled those of the prototype highly pathogenic A/chicken/Pennsylvania/1370/83 (H5N2) virus isolated in October 1983. These results suggest that unrecognized subpopulations of highly pathogenic virus may have infected Pennsylvania chickens for several months before emerging as the clinically manifest component of the virus population.

Animals↗
PubMed1991

Chemically induced tumors in transgenic mice carrying prototype human c-Ha-ras genes.

Three independent transgenic mouse lines carrying human prototype c-Ha-ras genes were established. Approximately 50% of the transgenic offspring of these lines developed spontaneous tumors within 18 months. Types of tumors were restricted to angiosarcomas, skin papillomas and lung or Harderian adenocarcinomas. Interestingly, all angiosarcomas (16/16) had point mutations at the 61st codon of the transgenes. Furthermore, they were also very susceptible to the chemical carcinogens, N-methyl-N'-nitrosourea (MNU) and dimethyl-benzanthracene (DMBA). Within 12 weeks after administration of MNU, the transgenic mice developed forestomach papillomas and then carcinomas very frequently, at the rate of almost 100% and almost all of the tumors had point mutations in their transgenes at the 12th codon from GGC (Gly) to GAC (Asp). All the carcinomas of the forestomach, lung and spleen induced by DMBA had point mutations at the 61st codon from CAG (Gln) to CTG (Leu). Because no somatic point mutations in the transgenes have ever been detected in normal tissues of the affected mice, these mutations seemingly activated the human prototype c-Ha-ras transgene. From these results, it is suggested that the somatic mutation of the human c-Ha-ras transgene plays a causative role in the occurrence of natural tumors and those induced by MNU or DMBA administration in transgenic mice. This transgenic mouse provides a unique screening system for chemicals that induce or suppress the tumorigenesis.

Animals↗
PubMedDate not supplied

The Corneal EyeSys System: accuracy analysis and reproducibility of first-generation prototype.

The EyeSyS Corneal Topography System manufactured by EyeSys Laboratories, Inc., Houston, Tex utilizes a unique data-acquisition design to perform rapid, cost-effective quantitative photokeratoscopy. We evaluated a first-generation prototype system. Repeated testing with this prototype demonstrated an accuracy and reproducibility to within 0.25 D on spherical surfaces. Similar results were obtained in testing aspherical surfaces without refocusing. Data from preliminary clinical studies are displayed for the following corneal conditions: normal, keratoconus, post-keratoplasty, and post-keratoplasty with wound ectasia. Advantages of the EyeSys System include rapid data analysis and display, ease of operation, and compact table-top size.

Adult↗
PubMed1979

Abstraction of prototypical information by adults and 10-month-old infants.

The primary purpose of this study was to investigate whether preverbal infants, when presented with exemplars of an artificially constructed category, would abstract a prototypical representation of the category, and if so, whether this representation was formed by either "counting" or "averaging" the features that were varying among category members. Two experiments are reported. In Experiment 1, a set of stimuli was developed and tested for which it was demonstrated that adult subjects would readily abstruct either a modal or an average prototypical representation. The type of representation abstracted was found to be dependent on the discriminability of the feature values. In Experiment 2, 10-mo.-old infants were tested using a habituation paradigm with the stimuli developed in the first experiment. The results of this study indicated that the infants were also able to abstract the featural information that was varying among the exemplars of the category, and the infants formed an internal represenatation of the category by averaging feature values. Thus, the results clearly imply that infants are able to constructively process visual information and hence take a more active role in category formation than had been previously believed.

Adult↗
PubMed1994

Prototyping a genetics deductive database.

We are developing a laboratory notebook system known as the Genetics Deductive Database. Currently our prototype provides storage for biological facts and rules with flexible access via an interactive graphical display. We have introduced a formal basis for the representation and reasoning necessary to order genome map data and handle the uncertainty inherent in biological data. We aim to support laboratory activities by introducing an experiment planner into our prototype. The Genetics Deductive Database is built using new database technology which provides an object-oriented conceptual model, a declarative rule language, and a procedural update language. This combination of features allows the implementation of consistency maintenance, automated reasoning, and data verification.

Animals↗
PubMed1994

Oncogenic activation of human R-ras by point mutations analogous to those of prototype H-ras oncogenes.

R-ras, K-rev-1/rap and TC21, are more closely related to prototype H-ras than any other known members of the ras superfamily. We recently isolated a mutationally activated TC21 oncogene from a human ovarian carcinoma cell line. Based upon these observations, we sought to re-examine the transforming potential of R-ras, which was reported earlier to lack transforming capacity. Mutations were introduced into the R-ras gene at codons 38 or 87, analogous to positions 12 and 61, respectively, responsible for H-ras oncogene activation. While both mutations resulted in acquisition of R-ras transforming capacity for NIH3T3 cells the position 61 was shown to be more active. Transfectants expressing either R-ras mutant formed colonies in soft agar and were tumorigenic in vivo. As has been reported for H-ras, R-ras cooperated with c-raf-1 in inducing transformation of NIH3T3 cells. These results imply interactions in R-ras and c-raf-1 signaling pathways. We observed R-ras transcripts of 4.6 and 1.2 kb ubiquitously expressed in each of a variety of tissues examined. All these findings raise the possibility that R-ras, like prototype ras genes, may be mutationally activated as an oncogene in some human malignancies.

3T3 Cells↗
PubMed1994

Oxygen performance of a prototype nonconventional hydrogel.

UNLABELLED: INTRODUCTION. Oxygen permeability (Dk) of available hydrogel materials used for soft contact lenses is currently restricted by the oxygen permeability of water at 80 Dk units. A predicted upper limit for conventional hydrogels amenable for use as a contact lens, has been 37 Dk units obtained with a water content of 80%. Methods for increasing oxygen permeability beyond that determined by water content must be explored, in order to further advance the physiological compatibility of hydrogel contact lenses. METHODS: Oxygen transport characteristics of a prototype nonconventional hydrogel contact lens material were derived in terms of human equivalent oxygen percentage (EOP) and thickness (L). The oxygen permeability of the material and oxygen transmissibilities (Dk/L) of various thicknesses were computed on the bases of a recently published nonlinear EOP vs. Dk/L relationship. RESULT: The material's oxygen permeability (Dk) was determined to be approximately 35 Dk units compared to 12.7 Dk units calculated for a conventional gel material having the same water content (52% H2O). Oxygen permeability equivalent to that obtained with high-water conventional gels was achieved using this mid-water nonconventional hydrogel. The prototype material was apparently also capable of low critical thicknesses typical of low-water conventional gels. DISCUSSION: Should new gel materials be durable with critical thicknesses in the "ultra-thin" range, nonconventional gel lenses could be capable of super and perhaps even hyper transmissibility with central minus lens EOP between 15-18.5% and Dk/L between 50-90 Dk/L units. The conventional relationships between water content and oxygen transmissibility of hydrogel contact lenses appear to have been surpassed. However, significant additional hurdles have yet to be overcome before nonconventional hydrogel materials can be ready for the ophthalmic marketplace.

Biocompatible Materials↗
PubMed1995

The informatics superhighway: prototyping on the World Wide Web.

We have experimented with developing a prototype Surgeon's Workstation which makes use of the World Wide Web client-server architecture. Although originally intended merely as a means for obtaining user feedback for use in designing a "real" system, the application has been adopted for use by our Department of Surgery. As they begin to use the application, they have suggested changes and we have responded. This paper illustrates some of the advantages we have found for prototyping with Web-based applications, including security aspects.

Computer Communication Networks↗
PubMed1994

Examination of tooth-drying techniques: evaluation in-vitro of a prototype warm-air tooth dryer.

A prototype, rechargeable, warm-air tooth dryer is evaluated and its capabilities compared with those of an established mains electricity powered dryer (Handi-Dri). The evaluation includes warm-up cycle, maximum temperature and constancy of temperature of air output, battery discharge profile, time required to dry etched enamel, ability to dry wet filter paper, flow rate and pressure of air output, convenience and ease of use. Selected tests were also applied to a dental 3-in-1 syringe. Alternative methods of drying the tooth surface are also reviewed. The prototype was found to be suitable for tooth drying; it was considered safer and more convenient than the Handi-Dri and offered advantages over other methods.

Air Pressure↗
PubMed1997

Prototype expert system to assist with the stabilization of neonates prior to transport.

The transport of sick or premature newborns from community hospitals to acute care facilities is often necessary for the infants to receive the level of care required. Prior stabilization of these infants is imperative to a successful transport. The knowledge required to treat and stabilize sick and premature newborns is specialized and may not be available in community hospitals. "The S.T.A.B.L.E. Assistant" is a prototype rule based decision support system based on the educational program "Transporting Newborns the S.T.A.B.L.E. Way". "The S.T.A.B.L.E. Assistant" accepts clinical information related to an infant's breathing status, blood glucose status and selected lab values and provides instructions as to what interventions are needed to stabilize and prepare the infant for transport. The computerized program was evaluated using data collected from 19 charts of newborns requiring transport from a community hospital to a tertiary care center. Patient data were entered into the computerized program and the subsequent instructions were reviewed by a group of neonatology and neonatal transport experts. Reviewers evaluated "The S.T.A.B.L.E. Assistant" for the safety of the program, the extent to which the computerized program follows the educational program guidelines and the degree to which the instructions generated are within the scope of community caregivers' practice. Results were positive, indicating "The S.T.A.B.L.E. Assistant" prototype is safe, and within the guidelines of neonatal clinical practice.

Decision Support Systems, Clinical↗
PubMed1998

Prototypes of intrafamily homicide and serious assault among insanity acquittees.

Public concern with societal violence is intensified when persons who have been found not guilty by reason of insanity (NGRI) of having committed a homicide or serious assault are returned to the community. Successful management of such acquittees in the community requires a sophisticated understanding of the person and the illness within the larger context of the violent incident, the family, the community, and the culture. In this article, we present an analysis of psychotic violence within a family context. A qualitative study of 64 subjects who were found NGRI of killing or seriously injuring a family member resulted in four prototypes of intrafamilial homicide/assault: Till Death Us Do Part; Overwhelming Burden, Elimination of the Limit Setter; and Family-Focused Delusional Killing. The prototypes are presented as a model for developing management strategies both for future risk assessment and for successful transition of the insanity acquittee into the community.

Adolescent↗
PubMed1998

The attributes of medical event-reporting systems: experience with a prototype medical event-reporting system for transfusion medicine.

OBJECTIVE: To design, develop, and implement a prototype medical event-reporting system for use in transfusion medicine to improve transfusion safety by studying incidents and errors. METHODS: The IDEALS concept of design was used to identify specifications for the event-reporting system, and a Delphi and subsequent nominal group technique meetings were used to reach consensus on the development of the system. An interdisciplinary panel of experts from aviation safety, nuclear power, cognitive psychology, artificial intelligence, and education and representatives of major transfusion medicine organizations participated in the development process. Setting.- Three blood centers and three hospital transfusion services implemented the reporting system. RESULTS: A working prototype event-reporting system was recommended and implemented. The system has seven components: detection, selection, description, classification, computation, interpretation, and local evaluation. Its unique features include no-fault reporting initiated by the individual discovering the event, who submits a report that is investigated by local quality assurance personnel and forwarded to a nonregulatory central system for computation and interpretation. CONCLUSIONS: An event-reporting system incorporated into present quality assurance and risk management efforts can help organizations address system structural and procedural weakness where the potential for errors can adversely affect health care outcomes. Input from the end users of the system as well as from external experts should enable this reporting system to serve as a useful model for others who may develop event-reporting systems in other medical domains.

Blood Transfusion↗