Information retrieved from a database and the augmentation of personal knowledge.

OBJECTIVE: To assess the degree to which information retrieved from a biomedical database can augment personal knowledge in addressing novel problems, and how the ability to retrieve information evolves over time. DESIGN: This longitudinal study comprised three assessments of two cohorts of medical students. The first assessment occurred just before student course experience in bacteriology, the second occurred just after the course, and the third occurred five months later. At each assessment, the students were initially given a set of bacteriology problems to solve using their personal knowledge only. Each student was then reassigned a sample of problems he or she had answered incorrectly, to work again with assistance from a database containing information about bacteria and bacteriologic concepts. The initial pass through the problems generated a "personal knowledge" score; the second pass generated a "database-assisted" score for each student at each assessment. RESULTS: Over two cohorts, students' personal knowledge scores were very low (approximately 12%) at the first assessment. They rose substantially at the second assessment (approximately 48%) but decreased six months later (approximately 25%). By contrast, database-assisted scores rose linearly: from approximately 44% at the first assessment to approximately 57% at the second assessment, to approximately 75% at the third assessment. CONCLUSION: The persistent increase in database-assisted scores, even when personal knowledge had attenuated, was the most remarkable finding of this study. While some of the increase may be attributed to artifacts of the design, the pattern seems to result from the retained ability to recognize problem-relevant information in a database even when it cannot be recalled.

Database access and problem solving in the basic sciences.

This study examined the potential contribution that access to a database of biomedical information may offer in support of problem-solving exercises when personal knowledge is inadequate. Thirty-six medical students were assessed over four occasions and three domains in the basic sciences: bacteriology, pharmacology, and toxicology. Each assessment consisted of a two-pass protocol in which students were first assessed for their personal knowledge of a domain with a short-answer problem set. Then, for a sample of problems they had missed, they were asked to use a database, INQUIRER, to respond to questions which they had been unable to address with their personal knowledge. Results indicate that for a domain in which the database is well-integrated in course activities, useful retrieval of information which augmented personal knowledge increased over three assessment occasions, even continuing to increase several months after course exposure and experience with the database. For all domains, even at assessments prior to course exposure, students were able to moderately extend their ability to solve problems through access to the INQUIRER database.

Influence of a computer database and problem exercises on students' knowledge of bacteriology.

This study compared the performances of students at the University of North Carolina at Chapel Hill School of Medicine who had access to sets of problem exercises and a computer database to support their learning of bacteriology with the performances of students at the University of Iowa College of Medicine who did not have such access. The study also examined the extent of a student's database use as a predictor of posttest performance. The students studied were randomly selected groups of 32-44 first-year students per year at each school; the study was conducted in three academic years (1988-1990) with some modifications in the intervention as the host environment evolved. The criterion measure was a posttest created from the same pool of problems used to generate the problem sets. The students at the intervention school scored significantly higher on the posttest in two of the three years, and overall. Also in two of the three years and overall, there was a significant relationship between the extent of a student's database use and his or her posttest score. Although the observed effects may have been due to other factors in this quasi-experimental design, the authors conclude that the use of problem sets and a computer database had a positive influence on the students' learning.

Studying the utilization and effects of a computer-based educational intervention in bacteriology.

We introduced a computerized database as part of a problem-oriented component of bacteriology instruction for first year medical students. This paper explores utilization of the computer resource and its effects on students' knowledge in the field.

Quantitative microlocalization of diffusible ions in normal and galactose cataractous rat lens by secondary ion mass spectrometry.

Secondary ion mass spectrometry (SIMS) is a surface analytical technique with high sensitivity for elemental detection and microlocalization capabilities within the micrometre range. Quantitative analysis of epoxy resins and gelatin have been reported (Burns-Bellhorn & File, 1979). We report here the first application of this technique to quantitative microlocalization in the context of a physiological problem--analyses of sodium, potassium and calcium in normal and galactose-induced cataract in rat lens. It is known that during the development of galactose-induced cataract the whole lens content of potassium is decreased, sodium is increased and, in late stages, calcium concentration increases. Whether these alterations in diffusible ions occur homogeneously or heterogeneously is not known. Standard curves were generated from epoxy resins containing known concentrations of sodium, potassium or calcium organometallic compounds using the Cameca IMS 300 Secondary Ion Mass Spectrometer. Normal and cataractous lenses were prepared by freezing in isopentane in a liquid nitrogen bath followed by freeze-drying at -30 degrees C. After dry embedding in epoxy resin, 10 microns thick sections of lens were pressure mounted on silicon wafers, overcoated with gold, and ion emission measured under the same instrumental conditions used to obtain the standard curves. Quantitative analysis of an area 27 microns in diameter, or a total analysed volume of 1.1 microns3, was performed by using a mechanical aperture in the ion optical system. Ion images provided qualitative microanalysis with a lateral resolution of 1 micron. Control rat lenses gave values for sodium and potassium content with a precision of +/- 17% or less. These values were compared to flame photometry and atomic absorption measurements of normal lenses and were accurate within 25%. Analysis of serum and blood also gave accurate and precise measurements of these elements. Normal rat lenses had a gradient of sodium, and, to a lesser degree, of potassium from the cortex to the nucleus. Development of galactose-induced cataract was heterogeneous by morphological criteria, beginning at the lens equator and spreading from the cortex into the nucleus. However, the loss of potassium and increase in sodium concentration occurred at early stages in both the cortex and nucleus cells, possibly because these cells are interconnected by gap junctions. There is a local alteration in elemental content prior to morphologically demonstrable cataract formation.(ABSTRACT TRUNCATED AT 400 WORDS)

Matrix effects in secondary ion mass spectrometric analysis of biological tissue.

We have made several observations during the course of our studies that show the presence of matrix effects in soft biological tissue and standards. The sputtering rate of gelatin is approximately twice that of epoxy resin, but the ion yield of lithium in gelatin is an order of magnitude less than in epoxy. Osmium impregnation of freeze-dried material significantly alters the localization of calcium, but not potassium and barium. The absolute count rate for calcium in osmicated tissue is increased several-fold above that in freeze-dried tissue. Scanning electron microscopy of sputtered material shows the formation of cones during sputtering, which is particularly, but not exclusively, associated with melanin granules and red blood cells. These structures are known to be highly emissive for Na, K, and Ca. Boron implanted tissue also exhibits selective boron emission from melanin granules. Relative proportions of monoatomic and polyatomic emission vary in epoxy, gelatin and tissue. Ion images of carbon, chlorine and vanadium in tissue embedded with a vanadium-doped epoxy resin show variations in local regions that correspond to tissue structure. The energy distributions of common secondary ions differed somewhat in resin and two different tissue regions. These examples show the existence of potential matrix effects in soft biological tissue that involve both differential sputtering and ion yield effects.