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.

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.

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.

Mieloma múltiplo: características clínicas e laboratoriais ao diagnóstico e estudo prognóstico / Multiple myeloma: clinical and laboratory characteristics in the diagnosis and prognostic study

O mieloma múltiplo (MM) caracteriza-se por expansão clonal plasmocitária na medula óssea e produção de imunoglobulina monoclonal, promovendo progressivamente destruição óssea, falência renal, supressão da hematopoiética e infecções. A identificação de fatores clínicos e laboratoriais ao diagnóstico é importante para predizer sobrevida. O sistema de estadiamento de Durie e Salmon (1975) é o mais utilizado e baseia-se na correlação entre parâmetros clínico-laboratoriais à massa tumoral. A combinação de β2 microglobulina e albumina sérica resultou em um sistema de estadiamento simples e confiável, conhecido como Sistema Internacional de Estadiamento (ISS), que tem sido reconhecido atualmente. O objetivo deste trabalho foi analisar as características clínicas e laboratoriais, ao diagnóstico, de pacientes portadores de MM e estudo de sobrevida. Realizou-se estudo de coorte não concorrente de 101 pacientes portadores de MM atendidos no Serviço de Hematologia do Hospital das Clínicas da UFMG, que receberam diagnóstico no período de abril de 1994 a 31 de outubro de 2006, através da coleta de dados contidos em prontuários médicos. Os pacientes foram acompanhados até maio de 2007. Foi feita análise descritiva das características ao diagnóstico e estudo de sobrevida, utilizando-se análise univariada pela técnica do produto-limite de Kaplan & Meier e teste de Log-Rank para comparação das curvas; já na análise multivariada, utilizou-se regressão múltipla de Cox. A mediana de idade dos pacientes foi de 63 anos de idade, 47,5 por cento eram homens e 52,5 por cento mulheres, sendo 50,6 por cento brancos, 33,3 por cento negros e 16,1 por cento pardos. Manifestações clínicas mais comuns foram: dor óssea (83,2 por cento), fraqueza (70,3 por cento) e perda de peso (40,6 por cento). Radiografia de esqueleto mostrou alterações em 83,8 por cento dos casos. Em relação ao sistema de estadiamento proposto por Durie & Salmon, 63 (62,4 por cento) pacientes...

Multiple myeloma (MM) is characterized by plasmocyte expansion in the bone marrow and the production of monoclonal immunoglobulin, causing bone destruction, renal failure, hematopoietic suppression and infections. Identification of clinical and laboratory factors in the diagnosis are important to predict survival. The Dürie/Salmon staging system, used for the disease, is based on the correlation of clinical and laboratory parameters on tumoral mass. Studies of the combination of β2 microglobulin and albumin resulted in a simple staging system, known as the International Staging System (ISS), which is currently being used. The objectives of this work were to analyze clinical and laboratory characteristics in the diagnosis of MM patients and a study of survival. A non-competitive cohort study was performed of 101 MM patients attended in the Hematology Service/Hospital das Clínicas-UFMG who were diagnosed in the period of April 1994 to October 2006.A descriptive analysis of the characteristics at diagnosis and a study of survival were made. The descriptive analysis was achieved using the Kaplan-Meier technique and the Log-Rank test utilized for a comparison of survival curves. The Cox regression test was used for multivariate analysis. The average age of the patients was 63 years, 47.5 percent were men and 52.5 percent women, with 50.6 percent being white, 33.3 percent black and 16.1 percent mulattos. The most common clinical manifestations were: bone pain (83.2 percent) and weakness (70.3 percent). Radiographies of the skeleton showed alterations in 83.8 percent of the cases. In respect to the Dürie/Salmon staging system, 63 (62.4 percent) patients were in stage III, 32 (31.7 percent) in stage II and 6 (5.9 percent) in stage I. Using the ISS classification, 22 (30.1 percent) patients were in stage III, 31 (42.5 percent) in stage II and 20 (27.4 percent) in stage I. Overall survival was 66.52 months with a follow-up of 20 months. In...

Mieloma múltiplo: verificação do conhecimento da doença em médicos que atuam na atenção primária à saúde / Multiple myeloma: assessment of knowledge of doctors working in primary healthcare

podem não ser identificados associados, dificultando e retardando o diagnóstico. A Atenção Primária à Saúde (APS) é a porta de entrada à rede de assistência à saúde no Brasil, por isso é importante o médico desse serviço reconhecer as características clínicas e laboratoriais do MM para conduzir adequadamente o paciente. Nosso objetivo foi verificar o conhecimento clínico e laboratorial sobre MM em médicos da APS. Foi realizado inquérito epidemiológico utilizando-se teste de múltipla escolha, aplicado em médicos das 137 Unidades Básicas de Saúde de Belo Horizonte (MG), entre outubro e dezembro de 2006. Doenças crônicas e neoplásicas em idosos foram reconhecidas como causas de anemia normocrômica e normocítica por 127 (94,1%) médicos;lesões osteolíticas ao Raio-X não foram associadas ao MM por 83 (61,5%); quadro clínico de hipercalcemia não foi clinicamente suspeitado pela maioria, 82 (60,7%); a eletroforese de proteínas foi incorretamente interpretada por 96 (71,1%) médicos eapenas 49 (36,3%) pensaram em MM diante de caso clínico característico. O tempo de graduação e de trabalho do médico na APS, assim como a existência de especialização médica, não influenciaram os resultados. Os sinais, sintomas e achados laboratoriais do MM não foram identificados por grande parte da população estudada, sendo umindicador da necessidade de maior interação entre os níveis de atenção secundária e primária, o que proporcionará educação compartilhada e continuada entre os profissionais dos diferentes níveis de atenção à saúde e maior eficiência no cuidado do paciente.

Multiple myeloma (MM) presents clinically with unspecific symptomswith an association that may not be identified, thus delaying the difficult diagnosis. Primary healthcare (PHC) is the doorway to the health system in Brazil; hence, doctors in this service should be able to recognize clinical and laboratorial characteristics of MM, inorder to manage the patient properly. Our objective was to verify clinical and laboratorial knowledge on MM of doctors working in PHC. An epidemiological survey was performed using a multiplechoice test completed by doctors of the 137 PHC units in Belo Horizonte(MG), between October and December 2006. Chronic and neoplastic diseases were recognized as causes of normochromic and normocytic anemia by 127 (94.1%) doctors; osteolytic lesions in the X-ray were not associated to MM by 83 (61.5%); clinical manifestations of hypercalcemia were not a clinical suspicion for the majority (82 - 60.7%); protein electrophoresis was incorrectly interpreted by 96 (71.1%) doctors and only 49 (36.3%) considered MM when presented with a characteristic clinical case. Neither timesince graduation, nor time working in PHCs, nor medical specialty influenced the results. A large proportion of the studied population failed to identify the signs, symptoms and laboratorial findings of MM, which indicates the need for a greater interaction between secondary and primary healthcare professionals, which will, in turn, promote shared and continuous education among professionals at the different levels of healthcare and a higher efficiency in patient care.

Biotin/avidin sandwich enzyme-linked immunosorbent assay for Culicidae mosquito blood meal identification

The knowledge of mosquitoes Culicidae host feeding patterns is basic to understand the roles of different species and to indicate their importance in the epidemiology of arthropod-borne diseases. A laboratory assay was developed aiming at standardizing the biotin-avidin sandwich enzyme-linked immunosorbent assay, which was unprecedented for mosquito blood meal identification. The enzyme-linked immunosorbent assay (ELISA) activity was evaluated by the detection of titers on each sample of the 28 blood-fed Culex quinquefasciatus. In light of the high sensitivity that the technique permits, by means of small quantities of specific antibodies commercially provided and phosphatase substrate which reinforces additional dilutions, human and rat blood meals were readily identified in all laboratory-raised Culex quinquefasciatus tested. The assay was effective to detect human blood meal dilutions up to 1:4,096, which enables the technique to be applied in field studies. Additionally, the present results indicate a significant difference between the detection patterns recorded from human blood meal which corroborate the results of host feeding patterns.

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.

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.

Avaliaçäo da qualidade físico-química e microbiológica do leite pasteurizado proveniente de mini e micro-usinas de beneficiamento da regiäo de Ribeiräo Preto/SP / Physicochemical and microbiological quality evaluation of the pasteurized milk processed by mini and microprocessing lants of the area of Ribeiräo Preto, State of Säo Paulo - Brazil

Foram analisadas, de 1995 a 1998, 390 amostras de leite (123 tipo C, 86 tipo B, e 181 tipo Integral) provenientes de dezesseis mini e micro-usinas da regiäo de Ribeiräo Preto/SP. Dentre essas usinas, dez foram submetidas a um estudo longitudinal, ou seja, as amostras de leite foram analisadas durante 4 anos, sendo que cada ano correspdeu a um período. Os estabelecimentos foram fiscalizados por um médico veterinário do Serviço de Inspeçäo de Säo Paulo que, mediante os resultados das análises de leite, orientava os responsáveis pelas usinas. Dentre o total de amostras estudadas, observou-se que estavam em desacordo com os padröes físico-químicos e microbiológicos, estabelecidos pela legislaçäo em vigor, 15,5 por cento e 32,5 por cento do tipo C; 37,2 por cento e 32,6 por cento do leite tipo B e 30,9 por cento e 31,0 por cento do tipo Integral, respectivamente. Na avaliaçäo das dez mini e micro-usinas estudadas durante os 4 anos observou-se, quanto a qualidade microbiológica, que o leite tipo B apresentou uma melhora a partir do terceiro período de estudo; o de tipo Integral também no terceiro período e depois manteve níveis um pouco mais altos no decorrer do estudo. Os dados mostraram que a fiscalizaçäo e orientaçäo resultaram em uma maior adequaçäo nas condiçöes higiênico-sanitárias do leite. O mesmo näo foi observado em relaçäo às características físico-químicas. (AU)

The objective of this research was to investigate the physicochemical and microbiological quality of pasteurized milk processed by mini and microprocessing plants of the area of Ribeirão Preto, State of São Paulo, Brazil. The total of 390 samples of pasteurized milk types C,B and whole were analyzed for their physicochemical and microbiological conditions. Ten of this mini and microprocessing plants were submmited a longitudinal study, and their milk samples were analized during four years. These factories were supervised by a veterinary of the Agricultural Secretary of São Paulo State who guided each responsible for factory about the results of the milk analises. The microbiological analysis showed that 32.5% of 123 samples of type C milk, 32.6% of 86 samples of type B milk and 31.0% of 181 samples of whole milk did not comply with the legal standards established by the Brasilian legislation. By the physicochemical analysis 15.5%, 37.2% e 30.9%, respectively, did not comply with legal standards in Brazil. Salmonella were negative in all samples. The evaluation of ten mini and microprocessing plants showed that the microbiological quality of the type B milk has a improved in the last two years, the type C milk showed an improvement only in the second year of the study and the type whole milk showed a significant improvement in the third period of study. The results of this study showed that the inspection and guidance resulted in improvement of the sanitary-hygienic quality of these products. (AU)

[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.

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.

Modulation of macrophage activation by prostaglandins.

The effect of prostaglandtn E(2), iloprost and cAMP on both nitric oxide and tumour necrosis factor-alpha release in J774 macrophages has been studied. Both prostaglandin E(2) and iloprost inhibited, in a concentration-dependent fashion, the lipopolysaccharide-induced generation of nitric oxide and tumour necrosis factor-alpha. The inhibitory effect of these prostanoids seems to be mediated by an increase of the second messenger cAMP since it was mimicked by dibutyryl cAMP and potentiated by the selective type IV phosphodiesterase inhibitor RO-20-1724. Our results suggest that the inhibition of nitric oxide release by prostaglandin E(2) and iloprost in lipopolysaccharide-activated J774 macrophages may be secondary to the inhibition of tumour necrosis factor-alpha generation, which in turn is likely to be mediated by cAMP.

Vascular cell adhesion molecule (VCAM)-Ig fusion protein defines distinct affinity states of the very late antigen-4 (VLA-4) receptor.

The Very Late Antigen-4 receptor (VLA-4) (alpha 4 beta 1) is constitutively expressed on leukocytes and plays a role in cell trafficking, activation and development through its interaction with two alternative ligands, Vascular Cell Adhesion Molecule (VCAM-1) and fibronectin (FN). VLA-4-dependent cell adhesion is augmented by various stimuli, such as divalent cations, certain beta 1-specific monoclonal antibodies (mAbs) and cell activation. However, the steps of the adhesive process which they affect are currently undefined. In order to investigate whether or not these stimuli affect the primary step, VLA-4/ligand binding, we employed a recombinant VCAM-IgG fusion protein (VCAM-Ig) as a soluble ligand for VLA-4. Using this soluble ligand, we have directly demonstrated that the VLA-4 receptor can exist in at least three different affinity states on the cell surface. Two distinct high affinity states are induced on normal peripheral blood T cells, one by the anti-beta 1 mAb TS2/16, and one of 15-20 fold higher affinity by the divalent cation Mn2+. Interestingly, activation through the T cell receptor (TcR), through CD31 or by the Macrophage Inflammatory Protein-1 beta chemokine (MIP-1 beta) do not detectably increase VLA-4 affinity although they do augment VLA-4 dependent cell adhesion in vitro. Thus, VCAM-Ig binding defines high affinity VLA-4 receptors, revealing unique effects of the TS2/16 mAb and Mn2+ cations in vitro, and distinguishes VLA-4/VCAM interactions from subsequent steps in cell adhesion.

Infecçäo humana por Hantavirus no sul e sudeste do Brasil / Human infection by Hantavirus in southern and southeastern Brazil

Descrevem-se os resultados de inquérito sorológico para pesquisa de anticorpos de Hantavírus conduzido de fevereiro de 1986 a agosto de 1990, em grupos populacionais humanos dos Estados de Säo Paulo e Paraná, que apresentavam estreito contato com ratos urbanos ou com roedores e outros pequenos mamíferos silvestres. OBJETIVO. Identificar infecçäo humana causada por Hantavírus, agentes etiológicos da febre hemorrágica com síndrome renal. MÉTODOS. Os soros de 1.063 pessoas foram examinados com técnica imunoenzimática para detecçäo de anticorpos IgG e IgM utilizando-se antígenos dos vírus Hantaan, Seoul e Puumala. Nos soros positivos realizou-se teste de neutralizaçäo com reduçäo em placa para os mesmos antígenos e imunofluorescência indireta para o antígeno do vírus Hantaan. RESULTADOS. Observou-se presença de anticorpos anti-Hantavirus em 32 pessoas, evidenciados por testes imunoenzimáticos e de imunofluorescência. Em cinco delas foram positivos os testes de neutralizaçäo com reduçäo em placa (três para o vírus Scoul e dois para o vírus Pumala). Uma dessas pessoas apresentou alto título em todos os testes para o vírus Seoul. Trata-se de um morador da zona rural da regiäo do vale do Ribeira, que nasceu, sempre viveu no local e nunca viajou para fora do Estado de Säo Paulo. CONCLUSOES. Há evidências sorológicas de infecçäo causada por Hantavírus em moradores de área rural da Ilha do Amparo, Baia de Paranaguá, e da regiäo do Vale do Ribeira, Estado de Säo Paulo, em portuários de Paranaguá, Estado do Paraná, e em doentes internados com suspeita de leptospirose no Hospital Emílio Ribas, Säo Paulo

[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.

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.

Continuous wave dye-laser technique for simultaneous, spatially resolved measurements of temperature, pressure, and velocity of NO in an underexpanded free jet.

Gas dynamic quantities within an underexpanded nitrogen free jet, seeded with 0.5% NO, were measured nonintrusively by using an intracavity-doubled, rapid-tuning, cw ring dye laser. The UV beam passed obliquely through the jet axis, and its frequency repetitively scanned across adjacent rotational lines in the NO gamma band near 225 nm at a rate of 4 kHz. Spatially resolved excitation scans were obtained by monitoring the induced broadband fluoresence. Modeling the Doppler-shifted excitation scans with Voigt profiles permitted simultaneous determinations of NO velocity, rotational temperature, and pressure. Zero Doppler shift was referenced to an absorption trace obtained across a static cell and recorded concurrently with the excitation scan. Typically, the measured and predicted axial distributions agreed within 10%. At high Mach numbers there was evidence of rotational freezing of NO.