Computer-Assisted Instruction Improves Clinical Reasoning Skills of Dietetics Students

Objective The effects of a computer-assisted instruction (CAI) tutorial program on learning clinical reasoning skills were compared in undergraduate dietetics students.Design A drill-and-practice program to control for time on task, a tutorial program, and a simulation program, as the test vehicle, were developed. The tutorial and simulation programs presented data on a patient with cardiovascular disease.Setting Subjects were tested in 30 undergraduate dietetics programs.Subjects Participants were 413 undergraduate diet therapy students enrolled in a coordinated program in dietetics (CPD) or a didactic program in dietetics (DPD).Intervention After completion of lectures on cardiovascular disease, subjects were given the drill-and-practice program plus a simulation test (group 1), the tutorial plus a simulation test (group 2), or the simulation test only (group 3).Main outcome measures Scores on the simulation test were compared. Variables included type of CAI, dietetics program, year in school, computer experience, and experience using a medical chart. Mastery of objectives related to lower- and higher-level clinical reasoning skills introduced in the tutorial program was compared.Statistical analysis One-way analysis of variance and Student-Newman Keuls tests were conducted to determine any differences among the three groups. Reliability was determined using the Kuder-Richardson Formula 20.Results The reliability coefficient of the simulation test was 0.93. Group 2 scored higher on the simulation test than group 1 or group 3. As a group, the CPD students scored higher than the DPD students. When CPD and DPD students were divided into the three experimental groups, there was no significant difference between the CPD and DPD student simulation scores. Group 2 mastered all objectives for lower-level reasoning skills and the higher-level decision-making objective better than groups 1 and 3.Applications/conclusions A computer tutorial program enhanced clinical reasoning skills in undergraduate dietetics students. This type of program could be used to supplement many topics taught in diet therapy and provide DPD students with experiential learning before their clinical intern practicums. J Am Diet Assoc. 1995; 95:868–873.     

Influence of Using Different Sources of Carotenoid Data in Epidemiologic Studies

Objective This study compared distributions of carotenoid intake and diet-serum correlations using two sources of carotenoid data: the US Department of Agriculture-National Cancer Institute (USDA-NCI) carotenoid food composition database and values accompanying the Block-NCI Health Habits and History Questionnaire (HHHQ).

Design and subjects A 100-item food frequency questionnaire was used to collect dietary data from 2,152 adults, aged 43 to 85 years, who were participating in the Nutritional Factors in Eye Disease Study, a population-based study designed to evaluate nutritional factors associated with age-related eye disease. Blood samples were collected from a random sample of 400 nonfasting participants in the study.

Results Median carotenoid intakes using HHHQ vs USDA-NCI data were alpha carotene (229 vs 223 μg/day), beta carotene (1,321 vs 1,325 μg/day), beta cryptoxanthin (72 vs 21 μg/day), lutein + zeaxanthin (653 vs 811 μg/day), and lycopene (593 vs 1,615 μg/day). All paired differences in carotenoid intake were significantly different from zero (Wilcoxon signed-rank, P<.0001). Despite these differences, the two databases similarly ranked individuals according to carotenoid intake: Spearman correlations ranged from .71 (lycopene) to .93 (alpha carotene). Differences between diet-serum correlations (adjusted for energy, body mass index, high density lipoprotein, and total cholesterol) using HHHQ vs USDA-NCI data were minor and not significant (P>.05): alpha carotene (r=.33 vs .32), beta carotene (r=.27 vs .32), beta cryptoxanthin (r=48 vs .53), lutein + zeaxanthin (r=.28 vs .24), and lycopene (r=.29 vs .25).

Conclusions Although estimates of carotenoid intake differed significantly, only minor differences in carotenoid rankings and diet-serum correlations were observed using either data source in this population. J Am Diet Assoc. 1996; 96:1271-1275.     

Culturally perceived illness and guinea worm disease surveillance

Surveillance is a central component of the international guineaworm eradication effort to aid planning, monitoring and certificationof disease elimination. The programme is based on a standardcase definition of 'a person exhibiting or having a historyof a skin lesion with emergence of a guinea worm'. Local namesfor and cultural conceptions of the guinea worm illness experiencevary from this definition, either by being non-specific or inclusiveof other presentations, thus setting the stage for false positivecase reporting. False reports have serious implications on decisionsto allocate disease control resources, especially in the remoteregions where guinea worm is endemic. A recent case search inone district of southwestern Nigeria provided an opportunityto determine the prevalence of the various cultural manifestationsof guinea worm. Only 65% of total cases reported matched thestandard case definition. Furthermore, an additional 26% ofsmall farm villages would have been targeted for programme intervention,had interviewers not verified positive responses. Previous workhad shown that local health staff were not sensitive to theimportance of the case definition. Thus there is need, not onlyfor ethnographic study preceding design of surveillance activities,but also for the involvement of local health staff in this processto increase their commitment to and understanding of eradicationefforts     

Five-Month Oral (Diet) Toxicity/lnfectivity Study of Bacillus thuringiensis Insecticides in Sheep

Five-Month Oral (Diet) Toxicity/Infectivity Study of Bacillusthuringiensis Insecticides in Sheep. HADLEY, W. M., BURCHIEL,S. W., MCDOWELL, T. D., THILSTED, J. P., HIBBS, C. M., WHORTON,J. A., DAY, P. W., FRIEDMAN, M. B., and STOLL, R. E. (1987).Fundam. Appl. Toxicol. 8, 236–242. Bacillus thuringiensisinsecticides (Bt) [Dipel (test substance D or Thuri-cide-HP(test substance T)] were administered in the diet for 5 monthsto castrated mixed ram-bouillet/merino sheep (24–34 kgat the beginning of the study) at a dose of 500 mg/kg/day (approximately10¹² spores per day). No treatment-related effect was seen onweight gain or clinical chemistry parameters nor were significantgross clinical changes observed. Several blood and tissue samplestaken just prior to the time the animals were killed or at necropsywere found to be positive for Bt when cultured. Detailed grossand microscopic pathologic examination of the sheep revealedseveral incidental lesions. However, the only lesion that mayhave been associated with the treatment was lymphocytic hyperplasiain Peyer's patches seen in the cecum of three sheep and it wasnot considered to be clinically significant.     

Diesel Exhaust Is a Pulmonary Carcinogen in Rats Exposed Chronically by Inhalation

Diesel Exhaust Is a Pulmonary Carcinogen in Rats Exposed Chronicallyby Inhalation. MAUDERLY, J. L., JONES, R. K., GRIFFITH, W. C.,HENDERSON, R. F., AND MCCLELLAN, R. O. (1987). Fundam. Appl.Toxicol 9, 208–221. Male and female F344 rats were exposed7 hr/day, 5 day/week for up to 30 months to automotive dieselengine exhaust at soot concentrations of 0.35, 3.5, or 7.0 mg/m³or were sham-exposed to clean air. Rats were terminated at 6-monthintervals to measure lung burdens of diesel soot and for histopathology.Other rats either died or were terminated after 30 months ofexposure. Lungs were fixed, sectioned into 3-mm slices, andexamined by a dissecting microscope to detect tumors. Lesionswere stained and examined by light microscopy. Survival andbody weight were unaffected by exposure. Focal fibrotic andproliferative lung disease accompanied a progressive accumulationof soot in the lung. The prevalence of lung tumors was significantlyincreased at the high (13%) and medium (4%) dose levels abovethe control prevalence (1%). Four tumor types, all of epithelialorigin, were observed: adenoma. adenocarcinoma, squamous cyst,and squamous cell carcinoma. Logistic regression modeling demonstrateda significant relationship between tumor prevalence and bothexposure concentration and soot lung burden. These results demonstratethat diesel exhaust, inhaled chronically at a high concentration,is a pulmonary carcinogen in the rat.     

Endocrine Modulation of Reproduction

The ability of foreign compounds to affect the functioning ofvarious endocrine systems is currently thought responsible fora wide variety of effects. The presentations in this Symposiumreviewed the evidence for and against the involvement of endocrinesystems in several different aspects of reproduction. The mechanismbehind the ability of a triazine herbicide to cause enhancedappearance of mammary tumors in one strain of female rats isreviewed by Stevens. The data suggest that enhanced aging, notdirect mammary modulation, is responsible. Dietary phytoestrogens,the mediators of their actions, their effects in various biologicalsystems, and the relationships between phytoestrogen producersand consumers are all provocatively and succinctly reviewedby Hughes. Kelce presents the strategy used to dissect the modeand mechanisms of action of a fungicide that opened a new awarenessin reproductive toxicology: the possibility of xenobiotics beingantiandrogens. Finally, to heighten our understanding of theinterplay among hormonal systems in vivo, Hess reviews the datathat show that androgens are not the only hormones importantin the development of the male reproductive system: the pituitaryis shown to play a critical role at specific stages of development.The breadth of these presentations, and the implications oftheir findings, should make us pause and realize how much thereis still to discover about the interaction between the reproductivesystem and anthropogenic compounds.     

An Analysis of Nasal Irritation Thresholds Using a New Solvation Equation

In the present paper we have developed a quantitative structure-activityrelationship (QSAR) equation for nasal pungency caused by nonreactivevolatile organic compounds (VOCs). Our QSAR was developed uponpreviously published nasal pungency thresholds in anosmics,i.e., patients lacking a sense of smell and thus respondingonly to sensory irritation evoked by trigeminal nerve stimulation.The reported solvation equation, which fits the data with considerableprecision, describes sensory potency in terms of interactionvia electron pairs, dipolarity/polarizability, hydrogen bondacidity and basicity, and hydrophobicity. It correspondinglysuggests relevant physicochemical properties of the biophasewhere the sensory response is brought about. The equation impliesthat in the range of molecular size where nonreactive VOCs canproduce any pungency, transport from the air to the biophasestrictly determines potency. In this respect, the potency ofnasal pungency shares characteristics with the ability of VOCsto cause narcosis and anesthesia.     

Chronic Dietary Toxicity/Oncogenicity Studies on 2,4-Dichlorophenoxyacetic Acid in Rodents

Forms of 2,4-dichlorophenoxyacetic acid (collectively knownas 2,4-D) are herbicides used to control a wide variety of broadleafand woody plants. Doses in the 2-year chronic/oncogenicity ratstudy were 0, 5, 75, and 150 mg/kg/day. The chronic toxicityparalleled subchronic findings, and a NOEL of 5 mg/kg/day wasestablished. A slight increase in astrocytomas observed (inmales only) at 45 mg/kg/day in a previously conducted chronicrat study was not confirmed in the present study at the highdose of 150 mg/kg/day. Doses in the 2-year mouse oncogenicitystudies were 0, 5, 150, and 300 mg/kg/day for females and 0,5, 62.5, and 125 mg/kg/day for males. No oncogenic effect wasnoted in the study. In summary, the findings of these studiesindicate low chronic toxicity of 2,4-D and the lack of oncogenicresponse to 2,4-D following chronic dietary exposure of 2,4-Din the rat and mouse.     

Detection of Aldehydes in Bronchoalveolar Lavage of Rats Exposed to Ozone

We report the detection of hexanal, heptanal, and nonanal inthe bronchoalveolar lavage (BAL) of rats exposed to 0.5 to 10ppm ozone with or without simultaneous 5% CO₂. These three aldehydesprimarily result from the Criegee ozonation of specific mono-or polyunsaturated fatty acids that are present in significantamounts in the rat lung; e.g., palmitoleic acid gives heptanal,oleic gives nonanal, and linoleic and arachidonic can give hexanal.Hexanal also is produced in the ozone-initiated autoxidationof any n-6 polyunsaturated fatty acid, and thus is a measureof generalized oxidative stress. (Monounsaturated fatty acidsdo not undergo appreciable autoxidation.) This detection andquantitation of aldehydes directly demonstrates for the firsttime that unsaturated fatty acids undergo Criegee ozonationin the lung when ozone is inhaled. Exposure to ozone alone producedsmaller apparent yields of the three aldehydes than did exposureto ozone plus 5% CO₂. Hexanal, heptanal, and nonanal can bedetected in BAL of rats 5 hr after the end of the ozone exposure,but after more than 5 hr only hexanal can be found, probablyfrom ozone-induced autoxidation of n-6 PUFA that continues afterozone exposure. The measured amounts of aldehydes are low, andthat, coupled with inherent biovariability, suggests that aldehydesmay not be useful as quantitative dosimeters. However, theycan be useful biomarkers, since some of these aldehydes (e.g.,nonanal) are produced in ozone-specific pathways and aldehydesare the most easily detected among the lipid ozonation products(LOP). Furthermore, our identification of these aldehydes byBAL, coupled with our recognition that ozone itself cannot penetratefar enough into the lung to cause many of the effects associatedwith the inhalation of ozone, suggests that these aldehydes,as well as other types of LOP (such as hydroxyhydroperoxidesand Criegee ozonides), may act as signal transduction molecules,activating lipases and causing the release of inflammatory moleculesby a variety of pathways not yet entirely elucidated.