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Biomedical subjects

J A Michael

Publications and source records attributed to J A Michael.

At least 19 recordsLinked to original sources
PubMed2000

Helping undergraduates repair faulty mental models in the student laboratory.

Over half of the undergraduate students entering physiology hold a misconception concerning how breathing pattern changes when minute ventilation increases. Repair of this misconception was used as a measure to compare the impact of three student laboratory protocols on learning by 696 undergraduate students at 5 institutions. Students were tested for the presence of the misconception before and after performing a laboratory activity in which they measured the effect of exercise on tidal volume and breathing frequency. The first protocol followed a traditional written "observe and record" ("cookbook") format. In the second treatment group, a written protocol asked students to complete a prediction table before running the experiment ("predictor" protocol). Students in the third treatment group were given the written "predictor" protocol but were also required to verbalize their predictions before running the experiment ("instructor intervention" protocol). In each of the three groups, the number of students whose performance improved on the posttest was greater than the number of students who performed less well on the posttest (P < 0.001). Thus the laboratory protocols helped students correct the misconception. However, the remediation rate for students in the "instructor intervention" group was more than twice that observed for the other treatment groups (P < 0.001). The results indicate that laboratory instruction is more effective when students verbalize predictions from their mental models than when they only "discover" the outcome of the experiment.

Exercise↗
PubMed2000

A custom confocal and two-photon digital laser scanning microscope.

We describe a custom one-photon (confocal) and two-photon all-digital (photon counting) laser scanning microscope. The confocal component uses two avalanche photodiodes (APDs) as the fluorescence detector to achieve high sensitivity and to overcome the limited photon counting rate of a single APD ( approximately 5 MHz). The confocal component is approximately nine times more efficient than our commercial confocal microscope (fluorophore fluo 4). Switching from one-photon to two-photon excitation mode (Ti:sapphire laser) is accomplished by moving a single mirror beneath the objective lens. The pulse from the Ti:sapphire laser is 109 fs in duration at the specimen plane, and average power is approximately 5 mW. Two-photon excited fluorescence is detected by a fast photomultiplier tube. With a x63 1.4 NA oil-immersion objective, the resolution of the confocal system is 0.25 microm laterally and 0.52 microm axially. For the two-photon system, the corresponding values are 0.28 and 0.82 microm. The system is advantageous when excitation intensity must be limited, when fluorescence is low, or when thick, scattering specimens are being studied (with two-photon excitation).

Animals↗
PubMed1999

Cardioversion of paroxysmal atrial fibrillation in the emergency department.

STUDY OBJECTIVE: Patients presenting to the emergency department with acute atrial fibrillation are traditionally admitted to hospital. The objective of this study was to review the success and safety of ED cardioversion and discharge of patients with acute atrial fibrillation. METHODS: This health records survey included a cohort sample of consecutive patients presenting with acute atrial fibrillation to the ED of a university-affiliated tertiary hospital. Patients who were in unstable condition on presentation, who had a complicating cardiac diagnosis, or those with other medical or surgical conditions requiring admission were excluded from the study analysis. Patient visit information was entered into a database that included demographics and clinical presentation, investigations, ED therapy, complications, consultations, disposition, and follow up. Patient visits were then categorized into the following groups: no ED intervention, spontaneous resolution, heart rate control, attempted chemical cardioversion, or electrical cardioversion. The data were analyzed using descriptive methods. RESULTS: Of the 289 eligible patients seen during an 18-month period, 62% (180) underwent attempted chemical cardioversion with a 50% success rate and 28% (80) had attempted electrical cardioversion with a 89% success rate. Ninety-three percent of electrical cardioversions were performed by emergency physicians. There was an overall 6% (19) complication rate, 95% of which were regarded as minor. One patient had a complication caused by a rate control medication, which necessitated hospital admission. Ninety-seven percent (280) of the patients were discharged home directly from the ED. CONCLUSION: Cardioversion and immediate discharge of patients who present to the ED with acute atrial fibrillation appears to be both safe and effective. This management approach should be prospectively evaluated in multiple settings.

Acute Disease↗
PubMed1999

Alertenone, a dimer of suberosenone from Alertigorgia sp.

Bioassay-guided fractionation of organic extracts of the gorgonian Alertigorgia sp. has yielded the previously known suberosenone (1), a cytotoxic tricyclic sesquiterpene of the quadrone class, and alertenone (2), a dimer of suberosenone. The structure of 2 was determined by spectral analysis; the 1D TOCSY experiment was particularly useful in the structure elucidation. Comparison of the in vitro cytotoxicity of alertenone and suberosenone revealed that the dimeric alertenone was devoid of cytotoxicity below 35 microg/mL. In a hollow-fiber assay model of in vivo activity, suberosenone exhibited some growth inhibition of two of six tumor cell lines tested.

Animals↗
PubMed1999

Undergraduate students' misconceptions about respiratory physiology.

Approximately 700 undergraduates studying physiology at community colleges, a liberal arts college, and universities were surveyed to determine the prevalence of our misconceptions about respiratory phenomena. A misconception about the changes in breathing frequency and tidal volume (physiological variables whose changes can be directly sensed) that result in increased minute ventilation was found to be present in this population with comparable prevalence (approximately 60%) to that seen in a previous study. Three other misconceptions involving phenomena that cannot be experienced directly and therefore were most likely learned in some educational setting were found to be of varying prevalence. Nearly 90% of the students exhibited a misconception about the relationship between arterial oxygen partial pressure and hemoglobin saturation. Sixty-six percent of the students believed that increasing alveolar oxygen partial pressure leads to a decrease in alveolar carbon dioxide partial pressure. Nearly 33% of the population misunderstood the relationship between metabolism and ventilation. The possible origins of these respiratory misconceptions are discussed and suggestions for how to prevent and/or remediate them are proposed.

Adolescent↗
PubMed1998

Students' misconceptions about perceived physiological responses.

Students' misconceptions about scientific phenomena can arise from at least two possible sources, the students' personal experience with those phenomena and things learned in the classroom. Misconceptions have been studied in a variety of science disciplines, but little attention has been given to the faulty models that students have for physiological processes. In this study 393 undergraduates in three different research universities were asked to predict the changes in heart rate and strength of cardiac contraction and breathing frequency and depth of breathing (physiological parameters that can be directly and personally perceived) under conditions that result in predicted that heart rate would increase but that the strength of contraction would decrease or stay unchanged. Approximately one-half of the students predicted that breathing frequency would increase but depth of breathing would decrease (also erroneous). Explanations for these erroneous predictions were elicited, and the reasons offered revealed significant misconceptions about cardiac and respiratory mechanics. The persistence of such misconceptions was demonstrated in a small group of first-year medical students. A general approach to detecting and remediating misconceptions is discussed.

Adult↗
PubMed1997

Implementation of the Ottawa Knee Rule for the use of radiography in acute knee injuries.

CONTEXT: The Ottawa Knee Rule is a previously validated clinical decision rule that was developed to allow physicians to be more selective and efficient in their use of plain radiography for patients with acute knee injuries. OBJECTIVE: To assess the impact on clinical practice of implementing the Ottawa Knee Rule. DESIGN: Controlled clinical trial with before-after and concurrent controls. SETTING: Emergency departments of 2 teaching and 2 community hospitals. PATIENTS: All 3907 consecutive eligible adults seen with acute knee injuries during two 12-month periods before and after the intervention. INTERVENTION: During the after period in the 2 intervention hospitals, the Ottawa Knee Rule was taught to all house staff and attending physicians who were encouraged to order knee radiography according to the rule. MAIN OUTCOME MEASURES: Referral for knee radiography, accuracy and reliability of the rule, mean time in emergency department, and mean charges. RESULTS: There was a relative reduction of 26.4% in the proportion of patients referred for knee radiography in the intervention group (77.6% vs 57.1 %; P<.001), but a relative reduction of only 1.3% in the control group (76.9% vs 75.9%; P=.60). These changes over time were significant when the intervention and control groups were compared (P<.001). The rule was found to have a sensitivity of 1.0 (95% confidence interval [CI], 0.94-1.0) for detecting 58 knee fractures. The K coefficient for interpretation of the rule was 0.91 (95% CI, 0.82-1.0). Compared with nonfracture patients who underwent radiography during the after-intervention period, those discharged without radiography spent less time in the emergency department (85.7 minutes vs 118.8 minutes) and incurred lower estimated total medical charges for physician visits and radiography (US $80 vs US $183). CONCLUSIONS: Implementation of the Ottawa Knee Rule led to a decrease in use of knee radiography without patient dissatisfaction or missed fractures and was associated with reduced waiting times and costs. Widespread use of the rule could lead to important health care savings without jeopardizing patient care.

Acute Disease↗
PubMed1992

The Predictions Table: a tool for assessing students' knowledge.

The Predictions Table (PT), a tool for determining students' knowledge, is described. The PT is a matrix consisting of a group of variables and a set of time periods. Students enter in the PT their qualitative predictions of the effects of a perturbation on a physiological system. The instructor or a teaching program can then evaluate the students' knowledge from these entries. An example is given from the teaching program CIRCSIM, which deals with blood pressure regulation. It shows the way that the program uses errors in the students' PT entries. CIRCSIM was evaluated and was found to have a statistically significant effect. It reduced the number of errors that students made in predicting the responses of the cardiovascular system to a perturbation. Also, students who worked in groups had significantly greater improvement than did control students. Using CIRCSIM also significantly reduces the number of relationship errors that the students make. They made even fewer errors when an instructor was present in the computer classroom while the students used CIRCSIM.

Computer-Assisted Instruction↗
PubMed1989

An agenda for research on teaching of physiology.

Calls to reform American medical education have not led to marked changes in the teaching of physiology. In large measure, this is the result of ignorance about how to most effectively teach physiology, a discipline requiring mastery of a complex domain in which the ability to solve problems is essential. However, contemporary cognitive science is beginning to provide us with the needed knowledge. After reviewing some of the key findings in this area, an agenda for research on topics specifically relevant to teaching physiology is proposed.

Models, Theoretical↗
PubMed1976

Oxygen microelectrode response to oxygen pressures up to 15 ATA.

Polarographic measurements of oxygen at high pressures were made at 21-22 degrees C with open-type Wood's metal microelectrodes with tip diameter about 5 mu. Although the sensitivity of the individual electrodes ranged from 3.1 x 10(-10) to 8.8 x 10(-12) amps/mm Hg of O2, the oxygen current was always a straight line function of Po2 from 21% O2 at ambient pressure (Po2 = 160 mm Hg) to 100% O2 at 200 psig (Po2 = 11,102 mm Hg). Compression to 200 psig with 100% nitrogen produced no significant change in microelectrode current, showing that the microelectrodes are insensitive to pressure alone.

Microelectrodes↗