Adverse learning strategy: the Adelaide Diagnostic Learning Inventory and its subscale replicability in a medical student population

The Adelaide Diagnostic Learning Inventory (ADLIMS) is a measure of learning styles and learning pathologies that was designed to investigate the impact of traditional approaches to learning versus problem-based learning and to identify students whose approach to learning tasks predicted poor academic performance. In this study, some important psychometric properties of the ADLIMS were examined, including its factor structure. In this study, factor replicability across samples was argued to provide a more robust and psychologically meaningful factor solution than that which can be obtained using traditional mathematical criteria. The results of the factor analysis did not confirm the presence of the four factor solution earlier reported for the ADLIMS, but did identify three clear factors that had very high replicability. An inspection of the items comprising these three factors showed that factor 1 tapped subjective distress related to poor study habits, lack of motivation to study, and distraction from social activities. Factor 2 tapped distress arising from high achievement expectations that were hampered by superficial or disorganized study habits that did not enable the student to grasp the relationships between concepts and ideas. Factor 3 tapped positive feelings and a sense of satisfaction associated with a problem-based approach to the learning of new study material. Although the internal reliability of the ADLIMS subscales met the requirements of a measure to be used in general research such as in the investigation of correlates among groups of medical students, they did not meet the higher requirements of a measure to be used to identify or predict individuals with pathological learning styles.     

Concept Mapping: An Effective Instructional Strategy for Diet Therapy

Concept mapping is an instructional strategy that requires learners to identify, graphically display, and link key concepts in instructional reading material. Although proven effective in numerous disciplines as a means to promote critical thinking and self-directed learning, concept mapping has not been tested in diet therapy. The objective of this study was to implement concept mapping as a small-group, cooperative learning strategy in an upper-division diet therapy course and to evaluate student attitudes about the effect of concept mapping on knowledge, self-directed learning, problem-solving, and collaborative skills. Students in the first semester (n=27) initially learned course material by lecture (4 weeks) followed by an integrated mapping/lecture format (12 weeks); the second semester (n=25) used an integrated mapping lecture format for the full 16 weeks. At the end of both semesters, students completed a 10-item original survey questionnaire. Responses for first (n=25) and second (n=21) semesters were analyzed independently. Results indicated that a majority of students thought participation in concept mapping enhanced knowledge of diet therapy principles (n=19 of 25; 18 of 21), self-directed learning (n=14 of 25; 18 of 21), critical thinking (n=21 of 25; 14 of 21), problem-solving (n=22 of 25; 16 of 21), and collaboration (n=24 of 25; 20 of 21) skills. When noncooperation of teammates was a factor, concept mapping was viewed as more frustrating and time consuming than lecture. This study demonstrated concept mapping as an effective learning strategy for diet therapy; it improves students’ ability to engage in self-directed learning, critical thinking, collaboration, and creative problem solving. Results suggest that concept mapping is most effective when accompanied with comprehensive training, coordinated lectures, instructor guidance, and long-term practice. J Am Diet Assoc. 1995; 95:908–911.     

Issues in the development of health promotion indicators

The rapid adoption of the concept of health promotion in recentyears, with the corresponding need to monitor health promotionendeavours, raises issues for the development of valid indicatorsof progress. A first step in such development is the differentiationof health promotion indicators from indicators of health status.The former constitute the means or methods to achieve the goalof enhancing health. The two types of indicators should be conceptuallydistinguished. Indicators must be refined, to tap the relevantdimensions of influences on health. Another major issue in thedevelopment of health promotion indicators is the excessivefocus on indicators of personal behaviour. Meaningful indicatorsare needed of the cultural, structural and situational processesthat affect health.     

A randomized, placebo-controlled trial of calcium supplementation for decreased bone density in corticosteroid-using patients with inflammatory bowel disease: a pilot study

Background: Patients with inflammatory bowel disease (IBD) have a high prevalence of osteoporosis. A number of studies have found that corticosteroid use is associated with the development of osteoporosis in these patients. Calcium supplementation may be of benefit in corticosteroid-induced osteoporosis and calcium may be a nutrient that patients with IBD lack. Aim: To test the benefit of calcium supplementation on bone density in a pilot study over a 1-year period, in a group of corticosteroid-using patients with IBD, in a randomized, double-blind, placebo-controlled treatment study. Methods: Corticosteroid-using patients with IBD including males over the age of 18 years and premenopausal females, were randomized to receive either calcium carbonate 1000 mg plus vitamin D 250 IU (Oscal) or an identically matched placebo. Dual energy X-ray absorptiometry measurements of bone density were obtained at entry and at 1 year. At entry, and every 3 months thereafter, serum was collected for the measurement of haemoglobin, biochemistry and bone hormones. Simultaneously a 24-h urine collection was analysed for calcium excretion and creatinine clearance, and a 4-day food record was collected to document dietary calcium and vitamin D ingestion. Results: We found a high prevalence of moderately severe decreased bone density in corticosteroid-using patients with IBD. The dose of prednisone in the year prior to study entry was inversely correlated with bone density at the hip (R=-0.67, P=0.004). At study entry serum osteocalcin was inversely correlated with corticosteroid dose in the year prior to the study (R=-0.64, P=0.02) and at study end, directly correlated with the percentage change in spine bone density (R=0.59, P=0.01). The dietary calcium intake of these patients was close to the current RDA (recommended daily intake) for premenopausal, post-adolescent adults. Calcium supplementation with small extra doses of vitamin D conferred no obvious benefit to bone density at the end of 1 year. There was no correlation between oral calcium ingestion and bone mass measurements. Both the treatment and placebo groups' bone density remained relatively stable at 1 year, suggesting that bone loss in corticosteroid-using patients may peak early into the use of the corticosteroids. Conclusions: Calcium supplementation (1000 mg/day) conferred no significant benefit to bone density at 1 year in patients with corticosteroid-using IBD patients with osteoporosis. Future investigations should explore other therapeutic avenues that may have greater effects on increasing bone density in patients who already have considerable osteoporosis.     

The Inhalation Toxicology, Genetic Toxicology, and Metabolism of Difluoromethane in the Rat

Difluoromethane (HFC32) is under development as a replacementfor chlorofluorocarbons (CFCs) in some refrigeration applications.It has been evaluated by standard studies of toxicity, developmentaltoxicity, and genotoxicity. In addition, the metabolism anddisposition of HFC32 was investigated and a physiologicallybased pharmacokinetic (PB-PK) model constructed. Inhalationof HFC32 (up to 50,000 ppm) caused no organ-specific effects,but resulted in slight maternal toxicity to the pregnant ratand rabbit and some fetotoxicity to the rat. HFC32 did not sensitizethe heart to adrenaline. The pharmacokinetics of [¹⁴C]difluoromethane(10,000 to 50,000 ppm/6 hr) revealed that about 2.1% of theinhaled HFC32 was absorbed and that steady state blood levelswere achieved within 2 hr and were proportional to dose. Carbondioxide was the major metabolite of HFC32 at all exposure levels.Carbon monoxide was not detected. The in vivo data were usedto validate a PB-PK model to describe the uptake and metabolismof HFC32. Absorption and distribution are adequately describedusing rat blood:air and tissue:air partition coefficients. Metabolism,which was linear across the dose range, was described by a firstorder rate constant (K_f=8.98 hr^–1). Of the absorbed HFC32,about 63% was metabolized at all doses; however, when metabolismwas expressed as a percentage of the inhaled dose it was muchlower, being about 1.4% of the HFC32 entering the airways. Overall,the results indicate that HFC32 is of very low toxicity andshould be an acceptable alternative to CFCs.     

Occupational transmission of HIV in health care workers: A review

Health care workers have a small but real risk of acquiringHIV infection as a result of occupational exposure. In thispaper, we review all reports in the scientific literature from1984 through to December 1993 of confirmed and probable casesof HIV seroconversion after a specific occupational exposure.A total of 64 confirmed cases have been reported, 24 in Europe,36 in the USA and 4 in other countries. Most seroconversionshave resulted from percutaneous exposure (91%) to AIDS patients(62%), usually caused by hollow bore needlestick injuries inflictedduring blood drawing procedures. Almost all seroconversionshave been detected within 6 months of exposure (94%) and haveusually been preceded by an episode of acute illness (73%).Ten seroconversions have occurred in spite of partial or completecourses of zidovudine prophylaxis. An additional 113 probablecases have been reported, 75 in the USA, 35 in Europe and 3in other countries. Aggregating the results of the prospectivestudies carried out, it is calculated that the risk of seroconversionfollowing percutaneous exposure is 0.33% or 3 in 1000 exposures(95% Cl: 0.21–0.52%), while the risk following mucocutaneousexposure is much lower (0.04%, 95% Cl: 0.006–0.31%). Thedocumented failure of zidovudine prophylaxis following occupationalexposure in a number of instances indicate its effect is, atbest, only partial; furthermore, exposure to source patientswho have been receiving the drug may lead to transmission ofzidovudine-resistant strains of HIV. Risk factors for occupationalexposure to HIV and for transmission, given that an exposurehas occurred, are discussed.     

The Effects of {alpha},{beta}-Unsaturated Aldehydes on Hepatic Thiols and Thiol-Containing Enzymes

The effects of series of ,ß-unsaturated aldehydeson hepatic giutathione, cytochrome P450, and NADPH-cytochromec reductase activity were compared with time. Male F-344 ratswere dosed with muconaldehyde (36 µmol/kg), acrolein (89µmol/ kg), crotonaldehyde (450 µmol/kg), or thesaturated aldehyde propionaldehyde (89 µmol/kg) and terminated0.5, 4, or 24 hr later. Acroiein or muconaldehyde reduced glutathioneto 51 and 75% of controls, respectively, at 4 hr; glutathionereturned control values at 24 hr. Only at 24 hr, acrolein, muconaldehyde,or crotonaldehyde decreased cytochrome P450 to 61, 71, and 67%of control values, respectively; ethylmorphine N-demethylationwas decreased to a greater extent, i.e., to 35, 60, and 23%of controls. The reductase activity was unchanged at any timefollowing the treatment with reactive aldehydes which were nothepatotoxic (as shown by glucose 6-phosphatase activity, histologicalchanges, or serum enzymes). Propionaidehyde changed none ofthese activities. Acroiein (44.5 mol/kg) given 4 hr prior tophenobarbital (50 mg/kg) for two consecutive days decreasedthe phenobarbital induction of cytochrome P450 45% of phenobarbitalalone. This treatment also decreased the 2, 2ß, 6ß,l6, and 16ß hydroxylation of testosterone as wellas androstenedione formation showing effects on individual cytochromeP450 isozymes. NADPH-cytochrome c reductase induction was notdecreased by this treatment, thus indicating that in vivo thesechanges are due to a mechanism other than generalized inhibitionof protein synthesis.     

Differential Expression of Photoreceptor-Specific Proteins During Disease and Degeneration in the Progressive Rod-Cone Degeneration (prcd) Retina

Progressive rod-cone degeneration (prcd) is a late-onset hereditary retinal degeneration characterized by normal development of photoreceptors prior to degeneration and death of visual cells. We reported previously that expression of opsin mRNA and protein decreases prior to visual cell degeneration. To examine the specificity of this reduction, we have used immunocytochemistry to correlate photoreceptor-specific protein expression with visual cell disease progression. Eyes from light-adapted age-matched control andprcd-affected dogs were fixed in paraformaldehyde, embedded in diethylene glycol distearate (DGD) wax, and reacted with antibodies specific to interphotoreceptor retinoid-binding protein (IRBP), S-antigen, opsin, phosducin, γ-phosphodiesterase (γ-PDE), and β₁-transducin. While IRBP expression did not change with disease progression, immunoreactivity to other proteins varied. For S-antigen and opsin, immunoreactivity decreased dramatically with the transition from photoreceptor disease to degeneration; γ-PDE immunolabeling in rods also decreased, but the reduction was less abrupt. However, for two other proteins (phosducin and β₁-transducin), immunoreactivity increased initially and was redistributed (particularly to the rod outer segment) in early disease (stage 1). Our results show that there is a differential expression of photoreceptor-specific proteins with disease and degeneration that is not uniform for all the gene products examined; expression can be decreased, altered in distribution or remain unchanged. It is clear that the decrease of opsin expression described previously is not an isolated phenomenon in the progression ofprcd, but is part of a more generalized degenerative process which eventually culminates in cell death.