Jane N. Scott

Using QuickTime Virtual Reality Objects in Computer-Assisted Instruction of Gross Anatomy: Yorick—the VR Skull

QuickTime virtual reality (QTVR) is a software technology that creates, on a normal computer screen, the illusion of holding and turning a three‐dimensional object. QTVR is a practical photo‐realistic virtual reality technology that is easily implemented on any current personal computer or via the Internet with no special hardware requirements. Because of its ability to present dynamic photo‐quality images, we reasoned that QTVR can provide a more realistic presentation of anatomic structure than two‐dimensional atlas pictures and facilitate study of specimens outside the dissection lab. We created QTVR objects, using portions of the skull, and incorporated them into an instructional program for first‐year medical students. To obtain images, the bones of the skull were mounted on a rotating table, and a digital camera was positioned on a swinging arm so that the focal point remained coincident with the rotational center of the object as the camera was panned through a vertical arc. Digital images were captured at intervals of 10° rotation of the object (horizontal pan). The camera was then swung through an arc with additional horizontal pan sequences taken at 10° intervals of vertical pan. The images were edited to place the object on a solid black background, then assembled into a linear QuickTime movie. The linear movie was processed to yield a QTVR object movie that can be manipulated on vertical and horizontal axes using the mouse. QTVR movies were incorporated into an interactive environment that provided labeling, links to text‐based information and self‐testing capabilities. This program, Yorick—the VR Skull, has been used in our first‐year medical and graduate gross anatomy courses for the past two years. Results of student evaluation of the program indicate that this QTVR‐based program is an effective learning tool that is well received by students. Clin. Anat. 13:287–293, 2000.

Critical Thinking: Change During Medical School and Relationship to Performance in Clinical Clerkships

The development of critical thinking, the ability to solve problems by assessing evidence using valid inferences, abstractions, and generalizations, is one of the global goals advocated by most medical schools. This study determined changes in critical thinking skills between entry and near the end of the third year of medical school, assessed the predictive ability of a test of critical thinking skills, and assessed the concurrent validity of clerkship components and final grade. The Watson–Glaser Critical Thinking Assessment (WGCTA) was administered to one class of students at entry to medical school and near the end of year 3. Performance data for those students who completed their clinical clerkships on schedule were also recorded. Critical thinking improved modestly but significantly from entry to medical school to near the end of year 3. The ability of a critical thinking test to predict clerkship performance was limited; the correlation between WGCTA total score at entry and the components and final grade of five major clerkships ranged from near 0 to 0·34. The concurrent validity of clerkship components and final grade was also limited; correlations with WGCTA total score near the end of year 3 ranged between 0·08 and 0·49. The correlation between WGCTA total score and United States Medical Licensing Examination Step 2 was higher at year 3 than at medical school entry. Critical thinking skills improve moderately during medical school. Used alone, tests of critical thinking may be of limited value in predicting which students will be successful in clinical clerkships. Clerkship evaluation components and final grade have limited concurrent validity when a test of critical thinking is the criterion.

Relationship between Critical Thinking Skills and Success in Preclinical Courses.

PURPOSE. To examine the relationship between critical thinking skills as measured by the Watson-Glaser Critical Thinking Appraisal (WGCTA) and success during the first two years of medical school. METHOD. The WGCTA was administered to 92 students participating in orientation for the class of 1994. Total scores and subtest scores were calculated for each student. Scores from the Medical College Admission Test (MCAT) subtests, undergraduate grade-point averages (GPAs), gender, race-ethnicity, and other premedical data were obtained from admission files. Measures of student success in medical school included the final numerical scores of preclinical courses, preclinical GPA, United States Medical Licensing Examination (USMLE) Step 1 total score, course remediations, and alterations in schedules such as reduced loads or repeated years. Pearson correlation and the t-test were used in the analysis of data. RESULTS. WGCTA scores correlated best with MCAT scores for reading skils (r = .57) and quantitative skills (r = .40). Significant correlations were found between WGCTA scores and final scores for nearly all preclinical courses; however, the only correlations reaching .40 were for Behavioral Science 1 and Biometrics. Correlations between WGCTA scores and first- and second-year GPAs and scores on the USMLE Step 1 were between .33 and .36. The WGCTA scores for students who had extended time to meet course requirements or altered their curricula were significantly lower than those of students who neither took extended time nor changed their academic schedules. CONCLUSION. Critical thinking skills as measured by the WGCTA are moderately predictive of academic success during the preclinical years of medical education.

Distribution of atrial natriuretic factor in fetal rat atria and ventricles

SummaryAn immunohistochemical study of rat fetal hearts at 20 days of gestation revealed the presence of immunoreactive atrial natriuretic factor (ANF) in cardiocytes of the left and right atria as well as in certain cells is the left and right ventricles. In the atria, cells of the adluminal pectinate muscles appear more densely labeled than the more peripheral mural cells. In the ventricles, immunoreactive cells were found only in adluminal cardiocytes of the presumptive trabeculae and papillary muscles. The results indicate that ANF is synthesized in the perinatal heart, and that the presence of this hormone in the ventricular cardiocytes may be of only temporary nature during certain stages of pre- and postnatal development.

Development of immunoreactive atrial natriuretic peptide in fetal hearts of spontaneously hypertensive and Wistar-Kyoto rats.

SummaryThe development of immunoreactive atrial natriuretic peptide (ANP) was studied in fetal hearts of spontaneously hypertensive (SHR) and compared to normotensive Wistar-Kyoto (WKY) rats. While SHR fetal hearts were noticeably less developed than those of WKY at 10 and 11 days gestation, both strains showed ANP immunoreactive cells in some but not all primitive heart tubes. At 12 days additional ANP immunoreactive cells appeared in formative trabeculae of the ventricle and atrium. ANP cells were also observed in the myogenic layer of the truncus and bulbus arteriosus and their derivatives from 11 through 16 days, but not at 18 days. In both strains, there were more ANP cells in the left ventricle than in right beginning at day 13. There were no obvious strain differences in the developmental pattern and timing of ANP producing cells. However, on the day of birth, staining was reduced in hearts from some WKY newborn pups compared with hearts from SHR newborns and ventricular staining was reduced in both strains when compared to fetal hearts. These observations indicate that ANP is one of the earliest peptide hormones produced and that the predisposition to genetic hypertension does not appear to influence the development of ANP.

Placental changes due to administration of diethylstilbestrol (DES)

SummaryPregnant mice were injected with 12.5 μg DES/kg body weight or 25 μg DES/kg body weight daily from gestation day 9 through day 12 or 16 and sacrificed on day 13 or 17. Placentas of DES treated animals were smaller than controls, the effect being dose dependent. Histologic changes in 13 gestation day placentas include regional thinning of the labyrinth associated with an apparent inhibition of trophoblast maturation and development of fetal blood vessels. Knots of mononuclear cells form in the labyrinthine region of 13 day placentas exposed to the higher dose of DES. By 17 days gestation, coagulative necrosis is common in the decidua basalis, being most severe in those animals receiving 25 μg DES/kg. In many placentas the labyrinthine region is absent. The only remaining elements are trophoblast cells, giant cells and glycogen-containing cells. Fetal deaths associated with the lower dose of DES increased with time whereas 100% fetal mortality was associated with the higher dose.

A Rapid, Noninvasive Method for Evaluation of Total Menstrual Loss

Three types of packages containing enough sanitary supplies for one menstrual period were weighed and distributed to 100 subjects to determine adequacy of supplies and compliance to protocol. Returned packages were then reweighed to determine total menstrual loss. No subject used all the supplies in her package; therefore, packages contents were deemed ample. 7 subjects added their own purchased products to their packages; since added products were specified by name, weight corrections were easily made. 2 subjects lost unused supplies which were specified, and weight corrections were made accordingly. Evaporative loss from sealed and stored and frequently opened packages was measured. 100 g distilled water were added to contents inside 60 packages which were sealed and set aside 7 days. Average loss from these packages was 0.65 +/- 0.57 g. 5 g water were added to 60 packages 4 times daily for 5 days (100 g total). Then packages were set aside for 2 days and weighed on day 7. Average loss from these packages was 1.25 +/- 0.85 g. The combination of storage plus frequent opening resulted in an average loss of 1.90 +/- 0.87 g. Thus, the direct-weight method permits recovery of 97-98% of sample.

Effect of Small Doses of Aspirin and Acetaminophen on Total Menstrual Loss and Pain of Cramps and Headache

90 women participated in a 4-month study. During the first 2 periods, they took no pain relievers whatsoever; during their last 2 periods they took 2 X 325 mg aspirin, acetaminophen or an identically packaged placebo every 4 h to total 8 tablets during the first 24 h of their periods beginning with spotting. For statistical analysis, periods 1 and 2 were combined and averaged, then compared with periods 3 and 4 combined and averaged. Total menstrual loss in grams, number of days of flow, and pain of cramps and headaches were analyzed by MANOVA for each of the three treatment groups. An ANOVA for each of these variables as well as for daily menstrual loss for the first 3 menstrual days was also performed. The MANOVA for all variables by the three treatment groups failed to show any significant differences. Similarly, ANOVAs for the individual variables failed to indicate significant differences except for the variable pain of cramps (p = 0.0072). The Duncans Multiple Range Test for pain of cramps showed that the average pain for the placebo group was higher than for either the aspirin or the acetaminophen group, although the means for these two groups were not significantly different. These results indicate that neither aspirin nor acetaminophen in the doses given alter either total menstrual loss or the pattern of loss during the first 3 menstrual days. However, both preparations were found to be more effective than placebo in reducing pain of cramps.

Fluoride ingestion during multiple pregnancies and lactations: microscopic observations on bone of the rat

SummaryFemale rats were given 150 ppm fluoride in the drinking water during three successive pregnancy and lactation periods; the femoral diaphyses were then examined for morphological alterations by light and scanning electron microscopy to determine the influence of fluoride ingestion during multiple pregnancies and lactations. The periosteal surface was dominated by areas of woven bone formation with some prolonged resting areas around osteocyte lacunae. The endosteal surface consisted mainly of areas of active bone resorption with some areas of bone formation. The interior of the cortex was characterized by numerous resorption cavities and remodeling in secondary Haversian systems. Fluoride, by the nature of its incorporation into bone crystals and by its direct cytotoxic effect on bone resorbing cells, reduces the availability of calcium from bone. It appears that fluoride ingestion during lactation created a heightened state of calcium homeostatic stress. As a result, bone mineral was mobilized by resorption of the endosteal surface and by cavitation of the interior of the cortex. Secondary hyperparathyroidism is thought to play an integral part in an attempt to maintain calcium homeostasis.

Placental and fetal contraindications of dexamethasone administration to pregnant rats

Dexamethasone (DEXA) given to pregnant rats for either the last 3 or 6 days of gestation lowered placental, fetal body and adrenal weights. Histologically, DEXA-treated placentas appeared smaller than controls and showed signs of necrosis and pyknosis. Treated animals that were permitted to carry their litters to term did not deliver naturally, and most of their fetuses were dead when excised 1 day postmaturely.