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Biomedical subjects

P Haug

Publications and source records attributed to P Haug.

At least 19 recordsLinked to original sources
PubMed1994

A natural language understanding system combining syntactic and semantic techniques.

A large proportion of the medical record currently available in computerized medical information systems is in the form of free text reports. While the accessibility of this source of data is improved through inclusion in the computerized record, it remains unavailable for automated decision support, medical research, and management of medical delivery systems. Natural language understanding systems (NLUS) designed to encode free text reports represent one approach to making this information available for these uses. Below we describe an experimental NLUS designed to parse the reports of chest radiographs and store the clinical data extracted in a medical data base.

Bayes Theorem↗
PubMed1993

Linking the Computerized Severity Index (CSI) to coded patient findings in the HELP system patient database.

The Computerized Severity Index (CSI) is a commercially available scoring system for hospital inpatients. Trained abstractors review the patient's paper medical record and enter the diagnoses and relevant physiological facts. The HELP (Health Evaluation Through Logical Processing) System at LDS Hospital stores patient data in discrete codes. We believe that HELP's coded patient database may drive an automatic version of CSI without the need for manual input. This descriptive study examines the nature and depth of the HELP System patient findings needed to implement an automatic CSI.

Databases, Factual↗
PubMed1991

Methods for knowledge extraction from a clinical database on liver diseases.

We performed exploratory data analysis (EDA) to examine the hidden structure in liver disease data. The purpose was to demonstrate the potential of statistical techniques for extracting knowledge from an active HIS (hospital information system) database with decision support. The goal is to give strong support to the creation of new rules or "tuning" of old rules in the knowledge base. This would facilitate utilization of large patient databases, now commonly available, to help build/update decision support systems for improved patient care. Several statistical techniques were investigated. Stepwise discriminant analysis was found to be a good method in discriminating among different disease classes. Results showed that classification strength of a few (3) variables was similar to all the available (19) variables. Other important issues in the work are treatment of missing values as well as atypical values in medical databases. In estimating missing values we utilized both statistical methods and artificial intelligence approaches. Both these approaches were promising in the estimation of missing values. The study showed that several statistical approaches are possible for knowledge extraction from clinical data collected retrospectively.

Artificial Intelligence↗
PubMed1991

Automated selection of clinical data to support radiographic interpretation.

Modern computerized hospital information systems can store much of the clinical information required for patient care. In some settings the amount of this information is great enough to interfere with its efficient use. Supplying information in support of radiographic interpretation provides an example of this problem. We describe an automated process that abstracts select data from a clinical database and creates a report recounting salient facts designed to assist the radiologist in interpreting the chest x-ray. The reporting system selects data using a combination of expert systems technology and information theory. It produces a brief summary of relevant clinical data. The original version of this process required run-time use of expert systems techniques that were time-prohibitive in the clinical setting. Through the use of pre-compiled tables of finding specific information contents we have reduced the time requirement to a point where the applications will soon be clinically feasible.

Databases, Factual↗
PubMed1991

Iliad training effects: a cognitive model and empirical findings.

Iliad is a diagnostic expert system consisting of an "inference engine" (collection of rules and procedures for making decisions) and a "knowledge base" (collection of medical facts). Iliad's internal medicine knowledge base recognizes 5000 medical findings and covers 1150 diagnostic conditions in 10 subspecialty fields. We used Iliad's simulator mode to train diagnostic skills in junior-year medical students. The results corroborate previous findings documenting Iliad's teaching efficacy. Recent developments in cognitive psychology provide a framework for explaining Iliad's training effects.

Clinical Clerkship↗
PubMed1983

Alterations in the content of amino acid neurotransmitters before the onset and during the course of methoxypyridoxine-induced seizures in individual rabbit brain regions.

In rabbits, generalized seizures were induced by methoxypyridoxine, and changes in amino acid concentrations of 15 brain regions were investigated before seizure onset and during the course of sustained epileptiform activity. As previously reported, gamma-aminobutyric acid (GABA) concentration decreased preictally in most regions. At the same time, taurine level was elevated in the hypothalamus, thalamus, hippocampus, caudatum, and frontal cortex. After 90 min of seizures, it was significantly decreased in the hypothalamus, periaqueductal grey, substantia nigra, frontal cortex, and cerebellum. Glycine content was reduced preictally only in the substantia nigra; after seizure onset its concentration rose in all brain areas. Glutamate content in the frontal cortex decreased before seizure onset; after 1.5 h of seizures, its concentration in cerebellum, caudatum, and hippocampus was reduced. Aspartate level was decreased in most areas after sustained seizures; in putamen, however, it was elevated. In contrast, glutamine content increased preictally in the superior colliculus and in all brain areas by approximately 200% after 90 min of seizures. Alanine and valine content also rose markedly in most brain areas after prolonged seizures, and threonine showed the same tendency. The single brain regions were observed to respond to methoxypyridoxine in highly individualistic ways. For example, the glycine content of the substantia nigra, which is believed to utilize this amino acid as a neurotransmitter, decreased preictally. The potential importance of the superior colliculus in seizure induction is considered in view of the early rise in glutamine level. The antagonistic preictal behavior of taurine and GABA is discussed with respect to synthesis, uptake from the blood, and antiepileptic properties.

Amino Acids↗
PubMed1982

Increase in taurine content before onset of seizures induced by a glutamate decarboxylase inhibitor.

The concentration of taurine was measured in 15 brain regions of the rabbit before the onset of convulsions induced by the potent glutamate decarboxylase inhibitor methoxypyridoxine. A significant rise in taurine content was observed in the hippocampus, putamen, caudate nucleus, frontal cortex, thalamus and hypothalamus. GABA levels determined from the same tissue samples were all significantly reduced. An unaffected taurine synthesis coupled with blocked transport to the blood is considered as a possible explanation for this taurine increase.

Animals↗
PubMed1982

Effect of motor and premotor cortex ablation on concentrations of amino acids, monoamines, and acetylcholine and on the ultrastructure in rat striatum. A confirmation of glutamate as the specific cortico-striatal transmitter.

At 1, 2, and 4 weeks after unilateral premotor and motor cortex ablation in rats, a significant and lasting decrease in glutamate levels in the ipsilateral versus contralateral striatum was observed. A significant corresponding fall in aspartate was seen only after 1 week. In contrast, there was a large increase in the striatal concentrations of lysine, threonine, alanine, and glutamine 1 week after the cortical ablation. This correlates with the extensive glial proliferation in the deafferented ipsilateral striatum. Four weeks after cortical ablation the GABA concentration was significantly increased. There was no decrease in other putative transmitters (dopamine, serotonin, acetylcholine, glycine and taurine), nor was a glutamate decrease observed in the hippocampus or in the hypothalamus, which do not receive direct premotor and motor cortical inputs. Both biochemical and morphological evidence for a minor contralateral cortico-striatal projection was obtained. Correlating with the fall in glutamate, ultrastructural observations indicated the degeneration of two types of striatal synapses, i.e., those of the axo-spinous type III and of the axo-dendritic type VII. Frontal cortex ablation clearly affects, in opposite directions, the metabolism of various striatal amino acids but not that of acetylcholine and the monoamine transmitters. The results strongly support the view that glutamate is the transmitter of the cortico-striatal fibers.

Acetylcholine↗
PubMed1980

Changes in acetylcholine in caudate nucleus tissue isolated in situ detected by gas chromatography mass spectrometry selected ion monitoring.

Acetylcholine neurons in the striatum are believed to be primarily intrinsic. In cats a cylinder of caudate tissue was isolated unilaterally from all afferent and efferent connections while preserving the blood supply through the base of the cylinder. Cats were decapitated two and four weeks after operation. Dorsal, intermediate and ventral portions of the viable isolated cylinder, and corresponding tissue from the contralateral hemisphere serving as control, were removed, weighed and frozen. Deuterated internal standards at concentrations approximating those of acetylcholine and choline in the tissue were added and acetylcholine and choline extracted, reacted with propionyl chloride and demethylated with sodium benzenethiolate. The derivatives were separated by gas chromatography, and the acetylcholine and choline concentrations in the tissue evaluated using selected ion monitoring of m/z 58, 60 and 64. The observed decrease in the acetylcholine concentration in the dorsal portion could be due either to the interruption of the cholinergic thalamic input or to the more severe ischemia in this portion. The increase in the acetylcholine concentration in the ventral portion, where blood circulation is normal, may reflect accumulation of acetylcholine in inactive intrinsic neurons after severance of their input, or indicate sprouting of intrinsic acetylcholine neurons.

Acetylcholine↗
PubMed1980

Selected ion monitoring determination of acetylcholine during methoxypyridoxine seizures.

The neurotransmitter gamma-aminobutyric acid is known to decrease preictally after administration of the potent convulsant methyoxypyridoxine, a competitive inhibitor of glutamate decarboxylase. An attempt was made to determine the effect of this gamma-aminobutyric acid decrease on the cholinergic system. Rabbits were immobilized and artificially ventilated in order to avoid hypoxidosis. Seizures were induced by intravenous injection of 100 mg kg-1 methoxypyridoxine; 40 minutes later the animals were decapitated and discrete brain areas removed. Tissue contents of acetylcholine and choline were estimated by gas chromatographic mass spectrometric analysis of the beta-dimethylaminoethyl acetate and propionate derivatives using deuterated internal standards. Gas chromatographic column optimization resulted in a considerable sensitivity gain. Computerized selected ion monitoring was carried out on the dimethylmethyleneimmonium ions using voltage switching. The use of a computer controlled solvent dump valve was implemented to increase precision. No significant difference was observed in the concentration of acetylcholine in the frontal cortex, cerebellar cortex, septum, hippocampus, or caudate of seizure versus control animals; septal choline increased, however. This suggests that the acetylcholine turnover could be increased during seizure.

Acetylcholine↗
PubMed1978

Role of debridement and interferon in the treatment of dendritic keratitis.

In a controlled clinical study, 42 patients with dendritic keratitis were treated either with thermocautery plus human leukocyte interferon (HLI) or with minimal wiping debridement plus HLI. The results show that the efficiency with which primary debridement was carried out, determined the success of further therapy using interferon. We conclude that interferon works basically as a prophylactic agent and needs the support of further antiviral measures to be effective against dendritic keratitis.

Debridement↗
PubMed1978

[The influence of Poly-HEMA and silicone contact lenses on corneal thickness (author's transl)].

The influence of permanent wear contact lenses (highly oxygen permeable silicone and less oxygen permeable highly hydrophilic Poly-HEMA) on corneal thickness was evaluated in 22 volunteers. Poly-HEMA lenses provoked a highly significant increase in corneal thickness not correlated with the fitting technique, while no significant variation in corneal thickness was observed under silicone lenses.

Contact Lenses, Hydrophilic↗