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PubMed2005

Comparison of measured dermal dust exposures with predicted exposures given by the EASE expert system.

Estimation and Assessment of Substance Exposure (EASE) is a rule-based computer expert system used by regulatory authorities within the European Union to assist in assessing exposure for both new and existing substances. It can provide estimates of both inhalation exposure levels and dermal exposure levels to the hands and forearms. This article describes the results of a study in which measurements of workplace dermal zinc exposures were collected for an industry-wide risk assessment and also compared with the levels predicted by EASE. Measurements were obtained from subjects in seven different workplaces that were producing or working with zinc metal or zinc compounds. The work activities were grouped a priori into one of three categories used by EASE for dermal exposure assessment: 'non-dispersive use with intermittent direct handling', 'wide dispersive use with intermittent direct handling' and 'wide dispersive use with extensive direct handling'. The predicted exposure ranges for these categories are 0.1-1, 1-5 and 5-15 mg cm(-2) day(-1). Although the average measured exposure levels for each of the categories increased in line with the predictions from EASE, the model overestimated dermal exposure to the hands by a factor of approximately 50 when the mid-point of the EASE range was compared with the measured mean exposure. Furthermore, a significant additional exposure was found on other parts of the workers' bodies for which EASE does not provide any estimates. Interpretation of the dermal exposure data was complicated by the use of protective gloves, which might have limited the amount of zinc dust adhering to the workers' skin. However, observation of the work activities suggested that the pattern of glove use was such that they would not provide a consistent level of protection. This study provided an opportunity to collect a large amount of dermal zinc exposure data for risk assessment purposes and also enabled a dermal sampling method to be developed and assessed. There is no standard method for dermal dust exposure measurement, and the choice of method was a key factor in the exposure estimation process. With regard to comparison with the EASE predictions, it is possible that EASE could appear to perform more accurately if its predictions were compared with measurements obtained using surrogate skin sampling methods. However, we believe that such sampling can provide a gross overestimate of the dust on the skin surface. We suggest that further development of the EASE system is necessary to ensure that it better reflects whole-body dermal exposures to dusts.

Dermis↗

PubMedDate not supplied

Certainty factor theory and its implementation in a medical expert system shell.

In this article some topics related to the MYCIN-model for uncertainty handling are discussed. First, it is pointed out that one of the problems identified by Adams should be considered as evidence supporting the point of view that the probabilistic interpretations of measures of belief and measures of disbelief given by Shortliffe are inappropriate. In this context some results achieved by Heckerman are reviewed, and it is shown that similar problems can be identified in the interpretation given by him. It is also pointed out that Heckerman's argument that the original probabilistic interpretation of certainty factors implies non-commutative evidence-updating is not correct. Then, in the context of the result achieved by Horvitz and Heckerman, in which it was proven that there is an isomorphic mapping from the evidence combination scheme for the likelihood ratio to the evidence combination function in EMYCIN and its successors, it is pointed out that the evidence combination scheme for the likelihood ratio suffers from a great restriction on its applicability in expert systems. Subsequently, some short remarks are made with respect to the complaint that sometimes the MYCIN model cannot work as well as expected. Lastly implementation of the certainty factor mechanism in a HIS-oriented expert system shell with some substantial changes is described.

Databases, Factual↗

PubMed1989

Computerized interactive morphometry. An expert system for the diagnosis of lymphoid-rich effusions.

The authors present experimental techniques for the diagnosis of malignant lymphoma and benign lymphocytosis in lymphoid-rich effusions with the use of an inexpensive microcomputer-based video system for computerized interactive morphometry (CIM). Lymphoid cells were randomly selected by a trained observer from real-time images of Papanicolaou-fixed and -stained cytospin smears prepared from pleural, peritoneal, or pericardial effusions. The lymphoid cells were classified by the instrument, based on the size and shape of their nuclear profiles. The morphometric data collected by the instrument were interpreted by a simple rule-based expert system that classified the smears as benign or malignant. One hundred four cases, including 28 malignant lymphomas, 63 benign lymphocytoses, 8 chronic lymphocytic leukemias, and 5 cases with incomplete immunopathologic data, were studied retrospectively. Sixty-three of these effusions had been stained to detect light chain monoclonality. Ninety-one effusions were correctly classified by the expert system. There were four potential false negative diagnoses and one potential false positive diagnosis by the CIM system. Eight effusions from patients with chronic lymphocytic leukemia (CLL) were consistently classified as benign. Although the author's series of patients with a history of CLL is small, their results suggest that CIM is unsuitable for the diagnosis of malignancy in these effusions. If only those effusions from patients with a history of CLL are excluded, the predictive value of a diagnosis of malignant lymphoma was 96.5%, whereas the predictive value of a diagnosis of benign lymphocytosis was 94.0%.

Algorithms↗

PubMed1997

Application of an expert system in the management of HIV-infected patients.

A rule-based expert system, Customized Treatment Strategies for HIV (CTSHIV), which encodes information from the literature on known drug-resistant mutations was developed. Additional rules include ranking and weighting based on antiviral activities, redundant mechanisms of action, overlapping toxicities, relative levels of drug-resistance, and proportion of drug-resistant clones in the HIV quasispecies. Plasma was obtained from HIV-infected patients and the RNA was extracted. Segments of the HIV pol gene encoding the entire protease, reverse transcriptase, and integrase proteins were amplified by reverse transcriptase-polymerase chain reaction (using a total of three primer pairs) and cloned. Sequencing was performed on five clones from each of two patients. When the patient's RNA sequencing data were entered into the expert program, and the information was downloaded directly into the CTSHIV program, the five most effective two, three, and four drug regimens coupled with an explanation for their choice were displayed for each patient. Thus, the CTSHIV system couples efficient genetic sequencing with an expert program that recommends regimens based on information in the current medical literature. It may serve as a useful tool in the design of clinical trials and in the management of HIV-infected patients.

Anti-HIV Agents↗

PubMedDate not supplied

[The use of the medical expert system in the diagnosis and treatment of myocardial infarct patients].

The authors consider it essential and expedient for patients with myocardial infarction that an expert medical system be created to diagnose and treat this condition. The presented structure of the created expert system incorporates data base, information base, and control system. Placed in the system as separate blocks are those of optimization and minimization securing clear cut medical recommendations in the output of the system. A variety of potential applications of the expert system are described together with expected results.

Cardiotonic Agents↗

PubMed2004

An expert system for cutaneous blood flow in melanocytic skin lesions.

A basic tool in microcirculation research is laser Doppler fluxmetry (LDF). The chaotic behaviour of the measured LDF-time series acquires mathematical tools like, for instance, Wavelets. The notion of contrast is known as useful tool to measure differences between two LDF-time series [K. Bräuer, Chaos, Attraktoren und Fraktale, Logos, Berlin, 2002]. The one time series arises from the blood flow in healthy skin and the other from a pigmented symmetric contra lateral skin lesion. Our approach is based on taking the contrast from all shorter non-overlapping time intervals of approximate length 5 or 10 seconds. This gives a sample or more precisely, a time series of contrast values. Our goal is an expert system to decide between malign and beligne lesions by estimating the probability for a maligne lesion. As a data base we again use the same data set as [H.-M. Häfner, K. Bräuer, M. Eichner, A. Steins, M. Möhrle, A. Blum and M. Jünger, Wavelet analysis of cutaneous blood flow in melanocytic skin lesions, J. Vasc. Res., submitted]. The statistical tool is logistic regression. We can show that 93% of data are correctly classified. If we check the expert system against the independent data base of the Greifswald dermatology department we get 78% correctly classified cases. Further work must be done to find a well distributed data base for an expert release system.

Blood Flow Velocity↗

PubMed1989

Expert systems survey on biodegradation of xenobiotic chemicals.

To determine the feasibility of developing an expert system for biodegradability assessment, a survey was conducted in which biodegradation experts were asked to estimate rates and products of degradation for 50 chemicals. These chemicals, which varied widely in structure, were considered representative of the spectrum of premanufacture notice chemicals subject to EPA review under the Toxic Substances Control Act. There was substantial agreement among the 22 experts on both sites of initial attack and rates of degradation. The approximate order in which various groups were viewed as contributing to aerobic biodegradability is as follows: ester, amide, anhydride greater than hydroxyl greater than carboxyl, epoxide, site of unsaturation greater than benzene ring, methyl, methylene. Hydrolyzable groups, azo bonds, halogens, and nitro groups were preferred sites of anaerobic attack. Among the negative influences on aerobic biodegradability were molecular mass, branching, halogenation, and nitrogen heterocycles. Results also indicate that estimates of removal by biodegradation in aerobic wastewater treatment and time for aerobic ultimate and primary degradation were well correlated, and that the predictive value of such correlations could be improved using correction factors for certain classes of chemicals. The results lend support to existing rules of thumb, but also offer additional insight that will prove useful in designing a prototype system.

Biodegradation, Environmental↗

PubMed1986

Computer sleep stage scoring--an expert system approach.

This paper describes the application of the expert system concept to sleep stage scoring and is aimed at managing the large variability found in such records. The primary computational burden, sleep parameter calculation, can be relieved by recognizing major classes of recordings or 'somnotypes' having internally consistent sleep parameters for each class but significant differences between classes. The initiation and evolution of somnotypes so as to maintain accuracy while introducing a variety of sleep recordings is treated. The technique is demonstrated on seven all-night recordings resulting in 89.6% accuracy for about 5000 pages of data.

Computers↗

PubMed1993

Pilot study of an expert system adviser for controlling general anaesthesia.

RESAC (real time expert system for advice and control), has been developed to advise on the concentration of inhaled volatile anaesthetics during anaesthesia. It merges clinical information and on-line measurements using Bayesian inference and fuzzy logic. This paper describes a clinical trial in seven patients after initial development of the knowledge base and the human computer interface. Evaluation of the performance of RESAC included analysis of questionnaire responses. Anaesthetists were confident enough to follow the dosage advice given by RESAC in most of the patients.

Adult↗

PubMed2005

The validity of the EASE expert system for inhalation exposures.

Estimation and Assessment of Substance Exposure (EASE) is a computerized expert system developed by the UK Health and Safety Executive to facilitate exposure assessments in the absence of exposure measurements. The system uses a number of rules to predict a range of likely exposures or an 'end-point' for a given work situation. The purpose of this study was to identify a number of inhalation exposure measurements covering a wide range of end-points in the EASE system to compare with the predicted exposures. Occupational exposure data sets were identified from previous research projects or from consultancy work. Available information for each set of measurements was retrieved from archive storage and reviewed to ensure that it was adequate to enable EASE (version 2) predictions to be obtained. Exposure measurements and other relevant contextual data were abstracted and entered into a computer spreadsheet. EASE predictions were then obtained for each task or job and entered into the spreadsheet. In addition, we generated a random exposure range for each data set for comparison with the EASE predictions. Finally, we produced exposure assessments for a subset of the data using a structured subjective assessment method. We were able to identify approximately 4000 inhalation exposure measurements covering 52 different scenarios and 28 EASE end-points. The data included measurements of solvent vapours, non-fibrous dusts and fibres. In 62% of the end-points the EASE predictions were generally greater than the exposure measurements and in 30% of the end-points the EASE estimates were comparable with the measurements. The random allocation of exposure ranges was, as expected, less reliable than EASE, although there were still about one-third of the cases where the randomly generated exposure ranges generally agreed with the measurements. The structured subjective assessments undertaken by a human expert produced exposure estimates in better agreement with the measurements with about two-thirds of the end-points derived from these assessments in good agreement with the data. We argue that the inhalation exposure estimates from EASE could be improved by incorporating some of the parameters included in the structured subjective assessment methodology.

Air Pollutants, Occupational↗

PubMed1986

[The assisted-diagnosis by identification program, an expert system for acquired ocular hypertension in adults].

Computer Aided Diagnosis by Identification packages are expert systems which proceed by iterative comparisons sign by sign between patient's cases and data encased in their clinical memory. They draw straight forward inference from thought processes analyses that lead to diagnosis: comparison between patient's own case report and acquired identified situation, error factors: ignorance or non-performance and, lastly rules to subscribe to: perfect knowledge of every kind of glaucoma and for every kind, perfect knowledge of every sign. Formalization of the problem specifies the algorithm, the miscellaneous solutions: single hypothesis and multiple hypothesis, and their respective values. In order to build up the clinical library, literature search is required to be comprehensive: treaty, reviews, papers, communications and personal case-reports. Outputs are retrieved in an average time-lag of 15 seconds, and are expressed as a list from which only the physician can make out the meaning.

Adult↗

PubMed1988

Heart-rate variability and SIDS. Examination of heart-rate patterns using an expert system generator.

In a prospective, population-based study, HRV was analyzed from 24-hr tape recordings made on 16 full-term and one preterm infant who had subsequently suffered SIDS and compared to similar data on 23 control infants (n of recordings, 44). In the SIDS group, heart rate was higher, and overall and beat-to-beat HRV (CV, CVS, respectively) were lower, than in the controls, but not significantly. Respiratory rate and respiratory HRV (by spectral analysis) were similar in both groups. Assuming that cardiorespiratory mechanisms of SIDS are multifactorial, we expected that several subgroups would be detected in both test groups. Therefore, the average data for each recording were subsequently examined by means of an expert system generator (ExTran, Intelligent Terminals Ltd., Edinburgh, UK). By rules induced with 25 nodes, the following results were obtained: 16/44 recordings were diagnosed as SIDS on the basis of (1) respiratory rate (RR) less than 33 and CV less than 3.46% (n = 8); (2) RR greater than 33, CVS less than 2.18%, and BW greater than 3,520 g (n = 4); and (3) RR greater than 33, CVS less than 2.18%, BW less than 3,520 g, HR greater than 136, and CV greater than 1.89% (n = 4). Seventeen of 44 were considered as non-SIDS when (1) RR was 33-47.4, CVS greater than 2.18%, and RSA less than 74.3 and (2) RR greater than 33, CVS less than 2.18%, BW less than 3,520 g, and HR less than 142. The remaining 11 cases required more complicated rules in order to be classified. This study shows that although the trend of increased HR and decreased HRV in the SIDS cases was statistically non-significant, an expert system program may be helpful in defining decision rules to identify cases of SIDS on the basis of cardiorespiratory data.

Decision Trees↗

PubMed1992

VALAB: expert system for validation of biochemical data.

In large laboratories that use "high-throughput" equipment, it is now possible to use artificial intelligence techniques to aid decision making and validation of data. This paper describes an artificial intelligence project, VALAB, that has been carried out in our laboratory. VALAB, an expert system that permits real-time validation of data, is designed to be equivalent to validation by the laboratory director. The decision produced by the expert system is based on several factors, including correlation between repeated laboratory results, physiological association between different variables, the hospital department from which the test was ordered, and the patient's age and sex. In 200 abnormal chemistry profiles randomly selected, VALAB's ability to detect abnormal cases (i.e., sensitivity = 0.75) was exceeded by only one of seven laboratory experts. However, all seven experts outperformed VALAB's measured specificity of 0.63. The VALAB system incorporates greater than 4000 rules. Operational since November 1988, it has validated greater than 50,000 medical patients' reports in real time.

Artificial Intelligence↗

PubMed1991

Expert system for predicting protein localization sites in gram-negative bacteria.

We have developed an expert system that makes use of various kinds of knowledge organized as "if-then" rules for predicting protein localization sites in Gram-negative bacteria, given the amino acid sequence information alone. We considered four localization sites: the cytoplasm, the inner (cytoplasmic) membrane, the periplasm, and the outer membrane. Most rules were derived from experimental observations. For example, the rule to recognize an inner membrane protein is the presence of either a hydrophobic stretch in the predicted mature protein or an uncleavable N-terminal signal sequence. Lipoproteins are first recognized by a consensus pattern and then assumed present at either the inner or outer membrane. These two possibilities are further discriminated by examining an acidic residue in the mature N-terminal portion. Furthermore, we found an empirical rule that periplasmic and outer membrane proteins were successfully discriminated by their different amino acid composition. Overall, our system could predict 83% of the localization sites of proteins in our database.

Bacterial Outer Membrane Proteins↗

PubMedDate not supplied

Is there a rational method to purify proteins? From expert systems to proteomics.

The purification of recombinant proteins for therapeutic or analytical applications requires the use of several chromatographic steps in order to achieve a high level of purity. A range of techniques is available such as anion and cation exchange chromatography, which can be carried out at different pHs, and hence used at different steps, hydrophobic interaction chromatography, gel filtration and affinity chromatography. Evidently when confronted with a complex mixture of partially unknown proteins or a clarified cell extract there are many different routes one can take in order to choose the minimum and most efficient number of purification steps to achieve a desired level of purity (e.g. 98, 99.5 or 99.9%). In this review we will show how an initial "proteomic" characterization of the complex initial mixture of target protein and protein contaminants can be used to select the most efficient chromatographic separation steps in order to achieve a maximum level of purity with a minimum number of steps. The chosen methodology was implemented in a computer based expert system. The first algorithm developed was used to select the most efficient purification method to separate a protein from its contaminants based on the physicochemical properties of the protein product and the protein contaminants. The second algorithm developed was used to predict the number and concentration of contaminants after each separation as well as protein product purity. The successful application of the expert system approach, based on an initial proteomic characterization, to the practical cases of protein mixtures and clarified fermentation supernatant is presented and discussed. The purification strategy proposed was experimentally tested and validated with a mixture of four proteins and the experimental validation was also carried out with an "unknown" supernatant of Bacillus subtilis producing a recombinant beta-1,3-glucanase. The system was robust to errors <10% which is the range that can be found in the experimental determination of the properties in the database of product and contaminants. On the other hand, the system was sensitive both to larger variations (>20%) in the properties of the contaminant database and the protein product and to variations in one protein property (e.g. hydrophobicity).

Animals↗

PubMed1993

Comparative study of human expertise and an expert system: application to the diagnosis of child's meningitis.

We present a general method of statistical evaluation for expert systems, applied to a system for the diagnosis of child's meningitis. Fifty difficult clinical cases of child's meningitis were submitted to the system, to seven senior specialists and to seven young physicians. Multidimensional analysis of the diagnosis of the infection category reveals that the two groups of physicians separate naturally and that the system is located among the group of experts. The study of the agreement of the microbiological diagnosis and therapeutic advice shows that the advice of the two groups of physicians is significantly different and that the advice of the system is significantly closer to that of the experts. This result is confirmed by the study of therapeutic errors. This type of study allows one to classify the performance of the system among physicians having different levels of expertise without referring to an objective solution.

Child↗

PubMedDate not supplied

["Slukh-3"--an expert system for the individual selection of hearing aids].

Herein is described the algorithm of an expert system intended for the individual choice of hearing aids, based on SM-4 computer. The audiometric data and hearing aids bank information allow to select for each patient the most preferable unit, regarded as suitable from the view of speech distinction. Moreover, with the help of this system it is possible to identify the most preferable way for manufacturing the audition prosthetic appliance (mono-or binaural) and to get recommendations for manufacturing prosthetic appliances for each ear individually; and for mono-aural prosthetic manufacturing--to identify the best version of the prosthesis for each ear individually. This system is most effective for the manufacture of audition prosthetic appliances for people with defective hearing.

Algorithms↗

PubMedDate not supplied

Development and validation of HEPAR, an expert system for the diagnosis of disorders of the liver and biliary tract.

HEPAR is an expert system in the field of hepatology which can be used as a supportive tool in the diagnosis of disorders of the liver and biliary tract. The representation language employed in HEPAR consists of production rules with object-attribute-value triples. In the system, medical diagnosis is modelled according to the strategy which is clinically used in this field. The patient's disorder is assessed in two stages. In the first stage, available data from medical interview, physical examination and simple laboratory tests are used to determine whether the disorder is hepatocellular or biliary obstructive in nature, and whether benign or malignant features are present. In the second stage the system produces a subset of possible diagnoses out of a set of more than 80 disease categories, using additional data from supplementary tests. The results of the first stage classification cause considerable pruning of the search space. In this paper the structure, development process and approach followed in the validation of the HEPAR system are described. The results of a recent performance validation study using data from 181 consecutive patient cases are discussed.

Biliary Tract Diseases↗