Fostering novice students' diagnostic ability: the value of guiding deliberate reflection.

BACKGROUND: Deliberate reflection when practising the diagnosis of clinical cases has been shown to develop medical students' diagnostic competence. Adding guidance by cueing reflection or providing modelling of reflection increased the benefits of reflection for advanced (Years 5-6) students. The present study investigated whether we could replicate and extend these findings by comparing the effects of free, cued and modelled reflection on novice students' diagnostic competence. METHODS: A total of 80 third-year medical students participated in a two-phase experiment. In the learning phase, students diagnosed nine clinical cases under one of three conditions: free reflection; cued reflection, and modelled reflection. Two weeks later, all students diagnosed four new examples of the diseases studied in the learning phase and four cases of non-studied related diseases ('adjacent diseases'). The main outcome measurements were diagnostic accuracy scores (range 0-1) on studied and adjacent diseases. RESULTS: For studied diseases, there was a significant effect of experimental condition on diagnostic accuracy (p < 0.02), with the cued-reflection group (mean = 0.58, standard deviation [SD] = 0.23) performing significantly better than the free-reflection group (mean = 0.41, SD = 0.20; p < 0.02). The cued-reflection and modelled-reflection groups (mean = 0.54, SD = 0.22) did not differ in diagnostic accuracy (p > 0.05), nor did the modelled-reflection group perform better than the free-reflection group (p > 0.05). For adjacent diseases, the three groups scored extremely low, without significant differences in performance (p > 0.05). Cued reflection and free reflection were rated as requiring similar effort (p > 0.05) and both were more demanding than studying examples of reflection (both p < 0.001) in the learning phase. CONCLUSIONS: Simply cueing novice students' reflection to focus it on relevant diseases was sufficient to increase diagnostic performance relative to reflection without any guidance. Cued reflection and studying examples of reflection appear to be equally useful approaches for teaching clinical diagnosis to novice students. Students found studying examples of reflection required less effort but cued reflection will certainly demand much less investment from teachers.

Effect of reflection on medical students' situational interest: an experimental study.

CONTEXT: Reflection has been considered crucial to learning. Engaging in reflection while solving problems is expected to foster identification of knowledge gaps and interest in learning more about them, the latter being a major motivational force in learning. Although theoretically sound, this assumption still lacks empirical evidence. This experiment investigated whether reflection while diagnosing clinical cases of different levels of difficulty influences medical students' awareness of knowledge gaps and situational interest. METHODS: Forty-two fourth-year students from a Brazilian medical school were randomly allocated to diagnose six clinical cases (three difficult; three easy), either by following a structured reflection procedure (reflection group) or by giving alternative diagnoses (control group). Subsequently, for each case, all students rated their situational interest and awareness of knowledge gaps. RESULTS: Situational interest was significantly higher in the reflection group than in the control group (mean = 4.10, standard deviation = 0.50 versus mean = 3.65, standard deviation = 0.48, respectively; p = 0.003; range, 1-5). The effect size was large (d = 0.92). Awareness of knowledge gaps was higher in the reflection group than in the control group, but the difference was not significant. Case difficulty influenced both situational interest, which was significantly higher on easy than on difficult cases (mean = 3.96, standard deviation = 0.56 versus mean = 3.80, standard deviation = 0.55, respectively; p = 0.004), and awareness of knowledge gaps, with higher scores observed on difficult compared with easy cases (mean = 3.99, standard deviation = 0.46 versus mean = 3.66, standard deviation = 0.53, respectively; p < .001). No interaction between experimental condition and case difficulty emerged. CONCLUSION: Relative to providing alternative diagnoses while solving cases, structured reflection increased medical students' interest and may therefore be a useful tool for teachers concerned with enhancing students' motivation for learning. Surprisingly, easy cases promoted higher situational interest despite the higher awareness of knowledge gaps on difficult cases. This suggests the potential for case difficulty to inhibit students' interest in learning, a possibility that demands further investigation.

Reflection as a strategy to foster medical students' acquisition of diagnostic competence.

OBJECTIVES: Developing diagnostic competence in students is a major goal of medical education, but there is little empirical evidence on instructional strategies that foster the acquisition of this competence. The aim of this study was to investigate the effects of structured reflection compared with the generation of immediate or differential diagnosis while practising with clinical cases on learning clinical diagnosis. METHODS: This was a three-phase experimental study. During a learning phase, 46 Year 4 students diagnosed six clinical cases under different experimental conditions: structured reflection, immediate diagnosis, or differential diagnosis. This was followed by an immediate test and a delayed test administered 1 week later. Each test consisted of diagnosing four different cases of diseases presented in the learning phase. Performance in diagnosing these new cases was used as a measure of learning. RESULTS: Repeated-measures analysis of variance on the mean diagnostic accuracy scores (range: 0-1) showed a significant interaction between performance moment (i.e. performance in the learning phase and on each test) and instructions followed during the learning phase (p=0.003). Follow-up analyses of this interaction showed that diagnostic performance did not differ between conditions in the learning phase. On the immediate test, scores in the reflection condition (mean=0.48, 95% confidence interval [CI] 0.38-0.58) were significantly lower than scores in the differential diagnosis condition (mean=0.62, 95% CI 0.54-0.70; p=0.012) and marginally lower than those in the immediate diagnosis condition (mean=0.61, 95% CI 0.52-0.70; p=0.04). One week later, however, scores in the reflection condition (mean=0.66, 95% CI 0.56-0.76) significantly outperformed those in the other conditions (differential diagnosis: mean=0.48, 95% CI 0.37-0.58 [p<0.01]; immediate diagnosis: mean=0.52, 95% CI 0.43-0.60 [p=0.01]). Comparisons within experimental conditions showed that performance from the immediate to the delayed test decreased in the immediate and differential diagnosis conditions (immediate diagnosis: p=0.042; differential diagnosis: p=0.012), but increased in the reflection condition (p=0.003). CONCLUSIONS: Structured reflection while practising with cases appears to foster the learning of clinical knowledge more effectively than the generation of immediate or differential diagnoses and therefore seems to be an effective instructional approach to developing diagnostic competence in students.

Specific interaction of lymphocyte function-associated antigen 3 with CD2 can inhibit T cell responses.

Accessory cell surface molecules, such as T cell antigen CD2 and its ligand lymphocyte function-associated antigen 3 (LFA-3; CD58), are critical costimulatory pathways for optimal T cell activation in response to antigens. Interaction of CD2 with cell surface LFA-3 not only increases T cell/accessory cell adhesion, but also induces signal transduction events involved in the regulation of T cell responses. In this report, we show that specific interactions of LFA-3 with CD2 can result in T cell unresponsiveness to antigenic or mitogenic stimuli in vitro. By deletion of certain regions of the extracellular domain of LFA-3, we localized the CD2 binding site to the first domain of LFA-3. We then demonstrated that a soluble, purified first domain-LFA-3/IgG1 fusion protein (LFA3TIP) interacts with CD2 and binds to the same CD2 epitope as purified multimeric or cell surface-expressed LFA-3. LFA3TIP inhibits tetanus toxoid, hepatitis B surface antigen, anti-CD3 mAb, Con A, and phytohemagglutinin P-induced T cell proliferation, as well as xenogeneic and allogeneic mixed lymphocyte reactions (MLR). Unlike anti-LFA-3 or anti-CD2 monoclonal antibodies (mAbs) which inhibit T cell responses by blocking LFA-3/CD2 binding, LFA3TIP is capable of rendering T cells unresponsive to antigenic stimuli in situations where T cell activation is independent of CD2/LFA-3 interactions. Furthermore, LFA3TIP, but not blocking anti-CD2 mAbs, is capable of inducing T cell unresponsiveness to secondary stimulation in allogeneic MLR. This inhibition of T cell responses by LFA3TIP occurs through a different mechanism from that of mAbs to LFA-3 or CD2.

An isomorphous heavy-atom derivative of crystaline formylmethionine transfer RNA.

An isomorphous osmium derivative of crystalline yeast initiator transfer RNA has been prepared and interpreted to 6-angstrom resolution. The coordinates of the heavy atoms have been determined by Patterson and "direct" methods applied to the difference coefficients of the centric projections, followed by least-squares refinement. There is one dominant site per asymmetric unit, consistent with the finding by neutron-activation analysis that there is approximately one osmium atom per molecule of transfer RNA. The osmium derivative appears to be a normal substrate for enzymatic aminoacylation.

Antibodies from patients with connective tissue diseases bind specific subsets of cellular RNA-protein particles.

We characterized the RNA-containing antigens precipitated by sera from 260 patients with positive antinuclear antibodies. 49 individuals, most of whom had systemic lupus erythematosus or Sjögren's syndrome, possessed antibodies that precipitated the previously identified RNP, Sm, Ro, and La antigens either singly or in combinations. These antigens, which are located on discrete sets of small nuclear or cytoplasmic RNA-protein particles, exhibited a number of antigenic interrelationships. One patient's serum recognized a new particle containing a small RNA which we have called Th; it also precipitated the Ro complexes. Other patients with systemic lupus erythematosus, hepatitis B virus infection, juvenile rheumatoid arthritis, myositis, and rheumatoid arthritis had antibodies that precipitated specific subsets of ribosomal RNA and transfer RNA. One patient's serum contained a monoclonal immunoglobulin G that precipitated ribosomes. Most of these antibodies identified antigenic determinants constituted at least in part of protein. The specificity of the proteins bound to particular cellular RNA, probably explains the exquisite precision with which antibodies from rheumatic disease patients discriminate among RNA subsets. Such sera should be useful probes for investigating specific roles that different RNA and RNA-protein complexes play in cellular metabolism.

Striking similarities are exhibited by two small Epstein-Barr virus-encoded ribonucleic acids and the adenovirus-associated ribonucleic acids VAI and VAII.

The nucleotide sequence of the region of the Epstein-Barr virus genome that specifies two small ribonucleic acids (RNAs), EBER 1 and EBER 2, has been determined. Both of these RNAs are encoded by the right-hand 1,000 base pairs of the EcoRI J fragment of EBV deoxyribonucleic acid. EBER 1 is 166 (167) nucleotides long and EBER 2 is 172 +/- 1 nucleotides long; the heterogeneity resides at the 3' termini. The EBER genes are separated by 161 base pairs and are transcribed from the same deoxyribonucleic acid strand. In vitro, both EBER genes can be transcribed by RNA polymerase III; sequences homologous to previously identified RNA polymerase III intragenic transcription control regions are present. Striking similarities are therefore apparent both between the EBERs and the two adenovirus-associated RNAs, VAI and VAII, and between the regions of the two viral genomes that specify these small RNAs. We have shown that VAII RNA as well as VAI RNA and the EBERs exist in ribonucleoprotein complexes which are precipitable by anti-La antibodies associated with systemic lupus erythematosus. Finally, we have demonstrated that the binding of protein(s) from uninfected cells confers antigenicity on each of the four virus-encoded small RNAs.

N-RAS and K-RAS gene mutations in Brazilian patients with multiple myeloma.

Point mutations affecting codons 12, 13 (exon 1) and 61 (exon 2) of the N-RAS gene and codons 12 and 13 (exon 1) of the K-RAS gene are identified in approximately 30.0% and 10.0%, respectively, of multiple myeloma (MM) patients living in the northern hemisphere. To date, there are no reports about the prevalence of RAS gene mutations in MM Brazilian patients, and this comprised the aim of the present study. DNA from bone marrow aspirates of 252 patients with MM (139 males and 113 females; aged 59.33 +/- 11.95 years) were investigated for whole exons 1 and 2 of the N-RAS gene and whole exon 1 of the K-RAS gene by direct sequencing of DNA amplified in vitro by the polymerase chain reaction. Fifty-three out of 252 (21.03%) MM patients presented RAS mutations. Heterozygous mutations at codons 4, 10 (exon 1), 61 and 65 (exon 2) of the N-RAS gene were identified in seven out of 252 (2.78%) patients. K-RAS heterozygous mutations at codons 7, 12, 13 (exon 1) were seen in 46 out of 252 (18.25%) patients. To the best of our knowledge, the mutation at codon 7 of K-RAS gene is reported for the first time in MM. Taken together, these results suggest that Brazilian MM patients are characterized by: (i) a low prevalence of RAS mutation and (ii) RAS mutations located at distinct regions of the critical codons of the N-RAS and K-RAS genes.

A humanized form of a CD4-specific monoclonal antibody exhibits decreased antigenicity and prolonged plasma half-life in rhesus monkeys while retaining its unique biological and antiviral properties.

Certain monoclonal antibodies (MAbs) directed against CD4 can efficiently block HIV-1 replication in vitro. To explore CD4-directed passive immunotherapy for prevention or treatment of AIDS virus infection, we previously examined the biological activity of a nondepleting CD4-specific murine MAb, mu5A8. This MAb, specific for domain 2 of CD4, blocks HIV-1 replication at a post-gp120-CD4 binding step. When administered to normal rhesus monkeys, all CD4+ target cells were coated with antibody, yet no cell clearance or measurable immunosuppression occurred. However, strong anti-mouse Ig responses rapidly developed in all monkeys. In the present study, we report a successfully humanized form of mu5A8 (hu5A8) that retains binding to both human and monkey CD4 and anti-AIDS virus activity. When administered intravenously to normal rhesus monkeys, hu5A8 bound to all target CD4+ cells without depletion and showed a significantly longer plasma half-life than mu5A8. Nevertheless, an anti-hu5A8 response directed predominantly against V region determinants did eventually appear within 2 to 4 weeks in most animals. However, when hu5A8 was administered to rhesus monkeys chronically infected with the simian immunodeficiency virus of macaques, anti-hu5A8 antibodies were not detected. Repeated administration of hu5A8 in these animals resulted in sustained plasma levels and CD4+ cell coating with humanized antibody for 6 weeks. These studies demonstrate the feasibility of chronic administration of CD4-specific MAb as a potential means of treating or preventing HIV-1 infection.

Evidence for the presence of substance P-like immunoreactivity in the human cerebellum.

Preliminary results on the localization of substance P-like immunoreactivity in the human cerebellum are presented. Cerebella from newborn and adult subjects were examined. While only sporadic positive fibres were detected in the adult tissue, the immunoreactive material appeared more abundant in the cerebella from newborn subjects. Varicose and non-varicose fibres and dot-like nerve terminals were present with different density in various regions. The paucity of immunoreactive perikarya suggests that most of the cerebellar substance P-like immunoreactive material has an extrinsic origin.

Effect of citric pectin on beta-carotene bioavailability in rats.

The effect of citric pectin on the bioavailability of synthetic beta-carotene was studied. Thirty Wistar rats were used, ten animals were sacrificed at the beginning of the experiment and remaining animals were divided into two groups and received the following diets for 30 days: control group (CG)--24 micrograms beta-carotene/g diet + 0% citric pectin; experimental group (EG)--24 micrograms beta-carotene/g diet + 7% citric pectin. Plasma and liver beta-carotene, vitamin A, and retinyl palmitate concentrations were determined by high-performance liquid chromatography (HPLC). Plasma retinol concentration was 1.42 +/- 0.36 mumol/L for CG and 1.10 +/- 0.24 mumol/L for EG (p = 0.1), and plasma beta-carotene concentration was 0.20 +/- 2.51 mumol/L for CG and 0.07 +/- 0.04 mumol/L for EG (p = 0.01). Only traces of retinyl palmitate were detected in CG and none in EG. Retinol did not differ significantly between groups CG and EG, while a significantly higher beta-carotene concentration was observed for CG. Liver concentrations of retinol (CG: 4.90 +/- 2.51 micrograms/g; EG: 2.68 +/- 1.12 micrograms/g), beta-carotene (CG: 0.98 +/- 0.28 microgram/g; EG: 0.11 +/- 0.06 microgram/g), and retinyl palmitate (CG: 95.47 +/- 45.13 micrograms/g, EG: 37.01 +/- 17.20 micrograms/g) differed significantly between groups (p < 0.05), with a lower concentration being observed for EG. We conclude that 7% citric pectin in the rat diet decreases the bioavailability of synthetic beta-carotene, reducing the liver reserves of vitamin A and beta-carotene.

[Recent occurrence of human infection by Rocio arbovirus in the Valley of Ribeira region]. / Ocorrência recente de infecção humana por arbovírus Rocio na região do Vale do Ribeira.

The presence of IgM antibodies to Rocio in sera of two children from rural area of Ribeira Valley, Brazil, was detected by MAC-ELISA. This new arbovirus of the Flaviviridae family was responsible for an extensive encephalitis epidemic that occurred in the region in 1975-1977. Since 1980 no human disease caused by this virus has been diagnosed. An improvement on surveillance of Rocio infections and on the researches for virus identification in suspected vectors and reservoirs is necessary.

[Subarachnoid hemorrhage, cerebral ischemia and endothelin-1]. / Hemorragia subaracnoidea, isquemia cerebral y endotelina-1.

INTRODUCTION: Cerebral vasospasm is involved in the development of delayed ischemic lesions in patients with subarachnoid hemorrhage. We developed an integral theoretical model to explain the pathophysiology of cerebral vasospasm, in which endothelin-1 has a pivotal role in the development of both cerebral vasospasm and delayed ischemic neurological deficits (DIND). OBJECTIVE: The objective of this study is to analyze the relationship between temporal profile of plasma endothelin-1 levels and the development of cerebral vasospasm and DIND. PATIENTS AND METHODS: We analyzed sequentially plasma endothelin-1 levels in 17 patients with aneurysmatic subarachnoid hemorrhage. All the patients had complete clinical and neuroradiological studies. Patients were classified according to Fisher's score. RESULTS: Patients (4 males and 13 females, aged 48.1 +/- 20.3 years) had a good clinical condition (Hunt-Hess < 4, GCS > 10). Two weeks after bleeding, patients had higher plasma endothelin-1 levels than healthy volunteers (p = 0.024). Patients who developed DIND had higher plasma endothelin-1 levels (p = 0.034) and a different evolution (p = 0.0146) than patients without DIND. There is a significant correlation (p = 0.02) between basal plasma endothelin-1 levels and GOS score. Multiple regression analysis shows a significant dependence between plasma endothelin-1 levels and Fisher's score (p = 0.0195), development of DIND (p = 0.0095), and GOS score (p = 0.0319). Logistic regression analysis finds a predictive relation between Fisher's score and plasma endothelin-1 levels for the development of DIND (overall predicted = 74.24%; p = 0.0148). CONCLUSIONS: Plasma endothelin-1 levels are increased in patients after subarachnoid hemorrhage and are associated with the development of cerebral vasospasm and DIND.

[Human infection by Hantavirus in southern and southeastern Brazil]. / Infecção humana por Hantavírus no Sul e Sudeste do Brasil.

The results of serological investigation on Hantavírus antibodies carried out between February 1986 and August 1990 in human populations of the States of São Paulo and Paraná, Brazil, which had close contact with urban rats or wild rodents and others small mammals are described. OBJECTIVE--To identify the human infection caused by Hantavíruses, which are the etiological agents of Hemorrhagic fever with renal syndrome. METHODS--Sera from 1063 persons were tested by enzyme immunoassay (ELISA) to Hantaan, Seoul and Puumala antigens. Plaque reduction neutralization test to the same antigens and indirect immunofluorescent test to Hantaan antigen were performed in the positive sera. RESULTS--Antibodies to Hantaan, Seoul or Puumala viruses were detected in 32 persons by enzyme immunoassay (ELISA) and immunofluorescent test. Plaque reduction neutralization test performed in these 32 sera were positive in 5 (3 for Puumala and 2 for Seoul viruses). One serum reacted with high titer to Seoul virus in all tests. It was from a male resident in the rural area of Ribeira Valley, State of São Paulo, where he was born and has always lived. He had only travelled inside the State of São Paulo. CONCLUSION--There are serological evidences of Hantavírus infections in residents of the rural areas of the Amparo Island, Paranaguá Bay, State of Paraná and the Ribeira Valley, State of São Paulo; in employees of the port of Paranaguá, State of Paraná and in patients of the Emílio Ribas Hospital, São Paulo, State of São Paulo, who had a presumptive diagnosis of leptospirosis.

Serodiagnosis as adjunct assay for pertussis infection in São Paulo, Brazil.

Pertussis remains an important public health problem in many countries despite extensive immunization. Cultures and real-time PCR (RT-PCR) assays are the recommended pertussis diagnostic tests, but they lack sensitivity at the later stage of the disease. This study introduces the IgG anti-pertussis toxin enzyme-linked immunosorbent assay (PT ELISA) in our routine diagnosis to improve disease burden estimation. Serum samples and nasopharyngeal swabs (n = 503) were collected at the same time from patients presenting with cough illness suspected of being pertussis and tested by the PT ELISA and culture and/or RT-PCR, respectively. Patients were separated into three age groups: group 1, <1 year (n = 260; mean age, 3 months), group 2, 1 to 6 years (n = 81; mean age, 3 years), and group 3, ≥7 years (n = 162; mean age, 26 years). The times (means) from cough onset to specimen collection were 16, 24, and 26 days, respectively. In group 1, 83 (82.2%) of 101 positive cases were positive for pertussis by culture/RT-PCR, while 40 (39.6%) tested positive by PT ELISA. In group 2, 6 (19.4%) of 31 positive cases were culture/RT-PCR positive, and 29 (93.6%) were seropositive. In group 3, 13 (13.8%) of 94 positive cases were positive by culture/RT-PCR and 91 (96.8%) were positive by serology. Culture/RT-PCR detected more cases of pertussis in infants (P < 0.0001), whereas the PT ELISA detected more cases in adolescents and adults (P < 0.0001). The timing between cough onset and specimen collection or recent vaccination may have partially affected our results. Serology is a suitable, cost-effective, and complementary pertussis diagnostic tool, especially among older children, adolescents, and adults during the later disease phase.