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Biomedical subjects

J R Beck

Publications and source records attributed to J R Beck.

At least 73 records · Page 4Linked to original sources
PubMed1991

Significant efficiency findings while controlling for the frequent confounders of CAI research in the PlanAlyzer project's computer-based, self-paced, case-based programs in anemia and chest pain diagnosis.

Richard E. Clark in his widely published comprehensive studies and meta-analyses of the literature on computer assisted instruction (CAI) has decried the lack of carefully controlled research, challenging almost every study which shows the computer-based intervention to result in significant post-test proficiency gains over a non-computer-based intervention. We report on a randomized study in a medical school setting where the usual confounders found by Clark to plague most research, were carefully controlled. PlanAlyzer is a microcomputer-based, self-paced, case-based, event-driven system for medical education which was developed and used in carefully controlled trials in a second year medical school curriculum to test the hypothesis that students with access to the interactive programs could integrate their didactic knowledge more effectively and/or efficiently than with access only to traditional textual "nonintelligent" materials. PlanAlyzer presents cases, elicits and critiques a student's approach to the diagnosis of two common medical disorders: anemias and chest pain. PlanAlyzer uses text, hypertext, images and critiquing theory. Students were randomized, one half becoming the experimental group who received the interactive PlanAlyzer cases in anemia, the other half becoming the controls who received the exact same content material in a text format. Later in each year there was a crossover, the controls becoming the experimentals for a similar intervention with the cardiology PlanAlyzer cases. Preliminary results at the end of the first two full trials shows that the programs have achieved most of the proposed instructional objectives, plus some significant efficiency and economy gains. 96 faculty hours of classroom time were saved by using PlanAlyzer in their place, while maintaining high student achievement. In terms of student proficiency and efficiency, the 328 students in the trials over two years were able to accomplish the project's instructional objectives, and the experimentals accomplished this in 43% less time than the controls, achieving the same level of mastery. However, in spite of these significant efficiency findings, there have been no significant proficiency differences (as measured by current factual and higher order multiple choice post-tests) between the experimental and control groups. Very careful controls were used to avoid what Clark has found to be the most common confounders of CAI research. Accordingly, this research proved Clark's rival hypothesis, that the computer, in itself, does not appear to contribute to proficiency gains, at least as measured by our limited post-testing. Clark's position is that the computer is primarily a vehicle--as is either a pill or a hypodermic needle for delivering a drug.(ABSTRACT TRUNCATED AT 400 WORDS)

Anemia↗
PubMed1991

Does the mediastinum of patients with non-small cell lung cancer require histologic staging? Future standards for computed tomography.

We asked whether noninvasive staging of the mediastinum is a reasonable alternative to invasive staging in patients with non-small cell lung cancer. Decision analysis was used to compare strategies relying upon mediastinoscopy, bronchoscopy with transbronchial needle aspiration, and/or thoracotomy for histologic or cytologic confirmation of mediastinal stage to two strategies primarily relying upon computed tomography for assessing the mediastinum. Life expectancy was the outcome of interest. Extensive sensitivity analysis showed that, if the specificity of computed tomography for mediastinal disease was above 0.90, a strategy primarily relying upon computed tomography to stage the mediastinum would provide a life expectancy within 1 month of that provided by invasive testing. The difference in life expectancy between the invasive and noninvasive staging strategies decreased further as the prior probability of unresectable disease increased. Surprisingly, the sensitivity of computed tomography for mediastinal disease was of little importance in determining overall life expectancy. These results suggest that noninvasive imaging techniques might reliably replace invasive mediastinal staging if their specificity exceeds 0.90.

Carcinoma, Non-Small-Cell Lung↗
PubMed1991

Flow cytometric analysis of granulosa cells from developing rat follicles.

Immature rats were treated with diethylstilboestrol (DES) or pregnant mares' serum gonadotropin (PMSG) and forward angle light-scatter (FALS) and 90 degrees light-scatter (90 degrees LS) signals were used to measure the size and the granularity (internal organization) of the granulosa cells, respectively. The results confirmed the presence of two major populations of granulosa cells in the ovaries of both groups of rats, with the same percentage of larger cells in both treatments (52.3% in DES, 49.5% in PMSG). Since DES treatment brings about granulosa cell growth while PMSG treatment causes growth and differentiation, it is evident that there is heterogeneity in granulosa cell sizes during different states of growth and differentiation. There was also heterogeneity in sizes of granulosa cells harvested from follicles of small (less than 210 microns), medium (210-420 microns) and large (greater than 420 microns) diameter. Quadrant analysis of granulosa cells in various fractions collected from Percoll gradients suggested an increase in granularity in the small and large granulosa cell populations. Cell cycle analysis of small and large granulosa cell populations collected from large follicles of rats treated with PMSG indicated that each population was distributed in G0/G1, S and G2/M phases. These results demonstrate that populations of small and large granulosa cells exist in rat ovarian follicles during various stages of growth and differentiation.

Animals↗
PubMed1991

A systems approach to planning biomedical information services.

A systems approach to planning was applied within the Biomedical Information Communication Center at Oregon Health Sciences University when its User Services division launched a strategic planning effort. By looking at the choice subsystem, the organizational structure, and the behavioral subsystem, those engaged in planning attempted to assure that desired change would permeate the entire system. The challenge of applying a theoretically ideal planning model within an environment averse to planning is delineated.

Information Centers↗
PubMed1991

Findings from an evaluation of PlanAlyzer's double cross-over trials of computer-based, self-paced, case-based programs in anemia and chest pain diagnosis.

We report on three years of research trials of the PlanAlyzer I Project--a carefully controlled research study using a microcomputer-based, self-paced, case-based, event-driven system for medical education. PlanAlyzer presents cases, elicits and critiques a second year student's approach to the diagnosis of anemias and chest pain. PlanAlyzer uses text, hypertext, images and critiquing theory. Students were randomized, one half becoming the experimental group who received the interactive PlanAlyzer cases in anemia, the other half becoming the controls who received the exact same content material in a text format. Later in each year there was a crossover, the controls becoming the experimentals for a similar intervention with the cardiology PlanAlyzer cases. Results at the end of the first two years of trials show that the programs have achieved some significant efficiency and economy gains. 96 faculty hours of classroom time were saved by using PlanAlyzer in their place, with no loss in student achievement. In terms of student proficiency and efficiency, combining the anemia and cardiology trials, the 328 students in the two years of full scale trials were able to accomplish the project's instructional objectives. The experimentals accomplished this in 43% less time than the controls. On the average, for both the anemia and chest pain programs, this amounted to students spending 7.5 hours longer on the 30 text cases than on the same 30 computer cases to achieve the same level of mastery. There have been no significant proficiency differences (as measured by current post-tests) between the experimental and control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Anemia↗
PubMed1990

Light microscope immunolocation of Bacillus thuringiensis kurstaki delta-endotoxin in the midgut and Malpighian tubules of the tobacco budworm, Heliothis virescens.

Light microscope immunofluorescence was used to localize the membrane binding of Bacillus thuringiensis kurstaki 63-kDa delta-endotoxin in Heliothis virescens midgut and Malpighian tubules. Staining was observed along all exposed mucosal (apical microvillar) plasma membranes. Interpretation of the serosal (basal) plasma membrane staining was complicated because the basal lamina also stained. The results suggest that the toxin binds to all exposed plasma membranes without apparent specificity for particular membrane domains.

Animals↗
PubMed1990

The effect of decision analysis on clinical uncertainty at tumor board.

Decision analysis is a formal approach to clinical decision making in the setting of uncertainty. Computer assisted clinical decision analysis was used at tumor board to help examine difficult oncological cases. Patients were identified early in the week and the decisions, possible outcomes, and uncertainties of each decision were modeled. These models were then presented at tumor board where the calculated expected utilities of each decision could be discussed. A description of decision analysis and three representative cases are presented here. These exercises were valuable for at least two reasons. First, modeling the problems confronting practicing oncologists was instructive as such. Second, the mathematical treatment of the probabilities and the utilities of the various outcomes for each decision stimulated a lively debate among the board members, forcing them to quantify probabilities and outcomes that they had previously ascertained qualitatively.

Bayes Theorem↗
PubMed1990

The conjunction fallacy?

Tversky and Kahneman (1983) showed that when subjects are asked to rate the likelihood of several alternatives, including single and joint events, they often make a "conjunction fallacy." That is, they rate the conjunction of two events as being more likely than one of the constituent events. This, they claim, is a fallacy, since the conjunction of two events can never be more probable than either of the component events. In addition, they found that prior training in probability theory does not decrease the likelihood of making this fallacy. We argue that in some contexts, an alternative that contains the conjunction of two events can be more probable than an alternative that contains only one of the conjunction's constituent events. We carried out four experiments in which we manipulated this context. The frequency of making a conjunction fallacy was affected by the manipulation of context. Furthermore, when the context was clearly specified, prior training in statistics influenced the ratings.

Decision Making↗
PubMed1990

A knowledge-based system for transfusion advice.

A knowledge-based system has been designed for evaluating the appropriateness of transfusion of non-red blood cell blood components. The goal of the system is to assist the blood bank physician in quality assurance efforts by automatically identifying cases of inappropriate transfusion before the blood is issued. Evaluation of a working prototype system shows that it is indeed capable of serving this function. The system identifies and summarizes cases, but it leaves consultation, education, and decision making to the blood bank physician. Small "expert systems" such as this may find use in quality assurance activities throughout the laboratory.

Blood Transfusion↗
PubMed1989

Computer-based exercises in anemia diagnosis (PlanAlyzer).

PlanAlyzer is a microcomputer-based, event-driven system for instructional research in medical education. Aimed at the second year medical student, PlanAlyzer elicits and critiques a student's approach to the diagnosis of a common medical disorder. In this paper we discuss the concept, development, implementation and formative evaluation of the PlanAlyzer system for the evaluation of anemia.

Anemia↗
PubMed1989

Detection of hepatotoxicity associated with methotrexate therapy for psoriasis.

To determine whether liver function tests and clinical and demographic information would predict methotrexate-associated hepatotoxicity, we identified 78 patients who had undergone 147 liver biopsies associated with methotrexate therapy for psoriasis. The joint sensitivity of aspartate aminotransferase, alkaline phosphatase, and total bilirubin values in detecting abnormal results from a biopsy specimen obtained after treatment was .86; the predictive value of negative test results was .93. A logistic regression model significantly predicted the presence of abnormal (grade III or higher) liver biopsy specimen results. The concordance index was .92 (perfect, 1.0). Regression coefficients may be used along with information from a specific patient to calculate the predicted probability of an abnormal result from a liver biopsy specimen after treatment. We conclude that this multivariate risk estimation model significantly predicts the likelihood of positive findings from liver biopsy specimens in this patient population. The clinical use of this model awaits further validation.

Biopsy↗
PubMed1989

Hypermedia in pathology--the Dartmouth Interactive Medical Record project.

Hypermedia and hypertext are the focus of intense interest in multiple disciplines in medicine, particularly pathology. This communication provides explanation of theories and applications that serve as motivation for the expansion of use of these technologies. The Dartmouth Interactive Medical Record (IMR) project is discussed.

Humans↗
PubMed1988

The dot plot. A starting point for evaluating test performance.

We suggest that evaluations of diagnostic tests start with dot plots that depict multiple test results over multiple clinical states. From this starting point we can calculate posttest probabilities for multiple clinical states at multiple test results. Also, we can project one subset of clinical states as "disease positive" and a second subset as "disease negative" to provide standard analyses such as likelihood ratios, relative operating characteristic curves, posttest/pretest probability plots, sensitivity, specificity, and predictive value. Finally, this starting point provides an excellent basis for comparing multiple studies of diagnostic performance. The advantages of dot plots are illustrated with data on serum ferritin levels over multiple clinical states.

Ferritins↗