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Biomedical subjects

H J Doller

Publications and source records attributed to H J Doller.

15 recordsLinked to original sources
PubMed1993

Epileptologist's assistant: a cost effective expert system.

Epileptologist's Assistant is an expert system designed to cost effectively handle routine care in an epilepsy follow up clinic. The system guides nurses in gathering patient histories and then generates progress notes and a patient information sheet. The progress note, organized in the SOAP format, is reviewed by the physician with the patient. For difficult cases the physician may modify the Assessment or Plan sections; the Subjective and Objective sections rarely need modifications. The assertion of cost-effectiveness is based on time/motion data. Without the system a physician in our epilepsy clinic spends about 21 minutes seeing a patient. With the system the nurse spends about 14 minutes with the patient and the physician spends about 7 minutes. Two nurses and a physician handle the work load of 3 physicians. Physician time is cut by about 66%. Using the average salaries for physicians and nurses at the Department of Veterans Affairs, the cost of a clinic visit is reduced 39% by using the expert system and nurses. In addition, the progress note is more legible, it contains more information, Q/A procedures are implemented at the point of patient contact, and the data is entered into a computer system in a data field format.

Ambulatory Care Facilities↗
PubMed1992

Assessment of a computer program to detect epileptiform spikes.

This study compares an automated spike detection program to a group of 6 electroencephalographers. Since group members varied in experience, an expertise factor was devised to weight their scoring. EEGers underscored epileptiform events on 6 records in a manner analogous to the computer's storage of EEG segments. A summation of expertise factors was determined for every event. This sum was normalized and interpreted as a probability the event would be called a spike by a given EEGer. The performance of each scorer and of the computer at different amplitude thresholds was analyzed based on this probability. Higher rated scorers identified more subtle events. Lowering the threshold of the computer program produced a comparable increase in sensitivity. The increase in total events detected by the computer was linear over the range studied. While the proportion of false positive detections increased with lowering threshold, our readers have not found a moderate number of these distracting. We conclude that the computer system, while not as specific as an EEGer, can be as sensitive and can be a reliable screening editor for large amounts of monitoring data. On balance it is more effective than an EEGer for this limited purpose.

Electroencephalography↗
PubMed1992

A cost effective expert system to assist physicians: epileptologists' assistant.

While medical expert systems helped demonstrate that artificial intelligence was possible, few medical systems have been heralded as practical successes. We believe that expert systems will be practical successes if they cost effectively handle most of a physician's workload (i.e., routine care). To accomplish this goal, technology must appear invisible to the user; the system must be intuitive and anticipate users' needs. "Epileptologists' Assistant" is an example of our approach of combining a graphical user interface with an expert system and data base in a system to help in a routine specialty clinic. The goal is for two nurses and a physician to handle the workload of three physicians while increasing the quality of care. The current system reduces physician time by 66%. Our ultimate goal is to create a unified family of systems for medical specialties.

Costs and Cost Analysis↗
PubMed1991

Modeling shift workers' scheduling desires: an application involving nursing personnel.

We are developing a computerized scheduling program that considers the schedule preferences of individual nurses. We want schedules that satisfy the staffing requirements of the unit and the work preferences of the nurses, while being fair. To reach this goal, we must calculate the desirability of every possible schedule for every nurse. The calculated preference scores of the schedules will be used by the computer to assign individual schedules and to keep a running tally of how well nurses' desires have been met. We present here the first model of nurses' scheduling desires. We modeled the schedule preferences as the desire to work the assigned shifts, plus the pattern of day-off, plus the pattern of tour splitting. Using this model, we account for an average of 81% of the variance.

Attitude of Health Personnel↗
PubMed1987

A nonlinear modeling procedure applied to hippocampal convulsant activity.

A strategy is described for fitting complex nonlinear models to experimental data. The procedure is demonstrated using an amplitude and frequency damped sine wave. The nature of the time dependency of the amplitude and frequency components was determined by fitting preliminary models to extreme data values and half-wave frequency estimates, respectively. In both cases, an exponential damping model fit the data. Parameter estimates from these preliminary models were used as starting values for a simultaneous nonlinear fit using all the data. Data used in this analysis were obtained from the picrotoxin-induced rhythmic discharges recorded from CA1 cells in vitro hippocampal slice. This analysis allows the response to be described by six parameters: a linear trend with slope and intercept, and a sinusoidal component with amplitude, amplitude decay, frequency, and frequency decay. This damped sine-wave model may be useful in quantifying seizure activity and the actions of convulsant and anticonvulsant drugs.

Animals↗
PubMed1985

Perforant pathway-evoked long-term potentiation of CA1 neurons in the hippocampal slice preparation.

Previously, we have presented electrophysiological evidence reaffirming the existence of a controversial hippocampal pathway. These fibers are part of the perforant pathway and terminate directly on the CA1 cells. We now report that, in the hippocampal slice preparation, tetanic stimulation of the perforant pathway produces long-term potentiation (LTP) of CA1 cell responses. LTP of population spikes varied from 150% to 500%. The results were of interest because these axons synapse at distal sites on the apical dendrite. This location is usually thought to be a difficult site to evoke action potentials.

Animals↗
PubMed1982

Perforant pathway activation of hippocampal CA1 stratum pyramidale neurons: electrophysiological evidence for a direct pathway.

Electrophysiological techniques were used to investigate the effect of stimulating the perforant pathway (PP) on pyramidal neurons in the CA1 region of the hippocampal slice. Stimulation of the PP evoked both field potentials and single unit discharges in the pyramidal cell layer of the CA1 region. Several lines of experimental evidence suggest that the CA1 response does not involve granule or CA3 neurons: (i) movement of the recording electrode in the CA1 region away from the site of stimulation in the PP and closer to the CA3 region increased the latency of the evoked potential; (ii) the sum of latencies of the individual pathways in a trisynaptic circuit - from the PP to granule cells to CA3 neurons to CA1 neurons - was 2-3 times longer than the latency of the PP evoked response recorded in the CA1 region: (iii) lesioning the mossy fiber pathway or excising the CA3 region did not inhibit the CA1 response to PP stimulation. Other experimental results suggest that the PP activation of CA1 pyramidal neurons involves a direct synaptic pathway: (i) PP stimulation evoked potentials with similar latencies in the dentate gyrus and the CA1 region; (ii) the CA1 response was abolished in a Krebs' solution containing low calcium/high magnesium; (iii) excising a portion of the CA1 region between the stimulating electrode in the PP and the CA1 recording electrode, but sparing the PP, did not abolish the CA1 response; (iv) electrolytic lesions of the PP abolished the CA1 response to PP stimulation, but did not affect the CA1 response to stimulation of the CA3 region. The data suggest that fibers in the PP make direct synaptic connection with pyramidal neurons in the CA1 region of the hippocampus.

Animals↗
PubMed1982

Development of the biochemical and morphological changes induced by administration of a beta-xyloside to chick embryos.

4-Methylumbelliferyl beta-D-xyloside was administered to 9-day-old chick embryos, and the morphological and chemical changes in the embryo were followed daily. Increases in wet weight, Na and Cl content, and visible edema were detectable at 10 days and fully apparent at 11 days. Dry weight increased to the same extent in control and treated embryos for four days, but then diverged. The degree of sulfation of chondroitin sulfate was slightly less in treated than control embryos at 10 days, and reached a steady low value at 11 days. Analysis of glycosaminoglycans in skin, muscle, and aorta showed an increase in chondroitin and its sulfates in the two former tissues but not the latter. In muscle and aorta, the degree of sulfation of chondroitin sulfate was markedly reduced; but in skin the results suggested a more complex picture in which the normal metabolism of glycosaminoglycans was altered. A possible physiological role is suggested for chondroitin sulfate in embryonic soft tissues.

Abnormalities, Drug-Induced↗
PubMed1979

Changes in chemical composition of chick embryos treated with a beta-xyloside and a lathyrogen.

Nine-day chick embryos were treated with 4-methylumbelliferyl beta-D-xyloside or beta-aminopropionitrile fumarate, and their gross chemical composition was examined one week later. Total DNA was 10--20% less in embryos treated with either drug than it was in control embryos. Xyloside-treated embryos showed marked increases in percent wet weight and in sodium/DNA and chloride/DNA ratios, and small decreases in protein/DNA, hydroxyproline/DNA and sulfate/DNA. None of these parameters was affected in embryos treated with beta-aminopropionitrile. Approximately 85% of the uronic acid of control embryos was present as chondroitin sulfate, with a degree of sulfation of 80% and charge density of 1.8; all of this chondroitin sulfate was covalently linked to peptide and had a number-average molecular weight of 29,300. In embryos treated with beta-xyloside, 90% of the uronic acid was present as chondroitin sulfate, with a degree of sulfation of 40% and charge density ranging from 1 to 2; 27% of this chondroitin sulfate, with an average molecular weight of 25,400, was peptide linked, while 73% was linked to 4-methylumbelliferone and had an average molecular weight of 22,900. The chemical differences between embryos treated with the xyloside and embryos treated with the lathyrogen reinforce the conclusion on morphological grounds that these are distinct syndromes involving different aspects of the extracellular matrix.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Levodopa pharmacokinetics. Alterations after benserazide, a decarboxylase inhibitor.

Plasma levodopa decay curves appeared to be triexponential up to 6 hr after single intravenous injections of levodopa in rats, rabbits, and dogs. After pretreatment of each of these three species with benserazide (Ro-4-4602), a decarboxylase inhibitor, plasma levodopa concentrations declined biexponentially. Administration of benserazide decreased both total plasma clearance and apparent volume of distribution of levodopa, but did not change the rate constant of the terminal phase of the plasma levodopa decay curve. Thus, decarboxylase inhibition failed to alter the plasma half-life of levodopa.

Animals↗
PubMedDate not supplied

Preferences for specific work schedules: foundation for an expert-system scheduling program.

An expert system was developed to schedule nurses according to their preferences for specific schedules. The first step in this project was to determine the reliability and stability of nurses' schedule preferences. If nurses' preferences changed frequently, the proposed expert system would not have been feasible. Our results show that for a 3- to 6-month period most nurses are consistent in their preferences of schedules. While each nurse is unique, cluster analysis indicates that it is possible to group nurses according to desire for tour.

Choice Behavior↗