Patient-embodied virtual reality as a learning tool for therapeutic communication skills among anaesthesiologists: A phenomenological study.

OBJECTIVE: In medicine, especially in a preoperative setting, training of effective communication skills is challenging, since communication is often implicatively copied from professional environment. This phenomenological study describes the development and experience of two patient-embodied virtual reality experiences designed to be used as an educational tool. METHOD: Two patient-embodied VR experiences from a first person patient perspective deployed negative or positive communication styles. The authors investigated the lived learning experiences of these VR tools through semi-structured interviews with ten anaesthesiologists adapting a thematic analysis framework. RESULTS: Interviews revealed acknowledgement of the importance of good communication skills. Overall, participants learned and adapted their style of communication 'on the job'. Patient-embodied VR was effective for a full immersive experience as participants expressed to have felt as if they had been a patient. They were able to distinguish differences in communication styles and analysis of the reflection showed a shift in perception, implying effective immersive experimental learning. CONCLUSIONS: This study elaborated the potency of experimental learning with VR in communication in a preoperative setting. Patient-embodied VR can influence beliefs and values and demonstrated effective as an educative tool. PRACTICAL IMPLICATIONS: The findings of this study can contribute to further research and healthcare education programs avid to use immersive learning with VR.

Does formative assessment help students to acquire prescribing skills?

PURPOSE: Formative assessments can help motivate students and ease students' learning through feedback. There is a pressing need for improvement of clinical pharmacotherapy (CPT) education since junior doctors make many prescribing errors. The aim of this study was to determine whether a formative assessment with personalized narrative feedback helps medical students to increase their prescribing skills. METHODS: This retrospective cohort study was conducted among masters' medical students at Erasmus Medical Centre, The Netherlands. Students made a formative and a summative skill-based prescription assessment, both during clerkships as part of their regular curriculum. Errors in both assessments were categorized by type and possible consequence and compared with each other. RESULTS: A total of 388 students made 1964 errors in the formative assessment and 1016 in the summative assessment. Most improvements after the formative assessment were seen for mentioning the weight of a child on the prescription (n = 242, 19%). Most new and repeated errors in the summative assessment were missing usage instructions (n = 82, 16% and n = 121, 41%). CONCLUSIONS: This formative assessment with personalized and individual narrative feedback has helped students to increase the technical correctness of their prescriptions. However, errors repeated after the feedback were predominantly errors showing that only one formative assessment has not yet enhanced the clinical prescribing enough.

Comparison of neuromuscular block measured by compressomyography at the upper arm and electromyography at the adductor pollicis muscle in obese and non-obese patients: An observational study.

STUDY OBJECTIVE: Quantitative neuromuscular monitoring is traditionally evaluated at the adductor pollicis muscle. By contrast, the TOF-Cuff compressomyograph evaluates neuromuscular block (NMB) at the upper arm. However, compressomyography has not been fully validated against other monitoring entities. This study evaluates the agreement between NMB measured by compressomyography at the upper arm and electromyography at the adductor pollicis muscle during various levels of neuromuscular block in patients with and without obesity. INTERVENTIONS: NMB was measured at the upper arm by compressomyography (TOF-Cuff) and by electromyography (GE-NMT) at the adductor pollicis. DESIGN: Prospective, multicenter, observational study. SETTING: Secondary and tertiary care hospitals' operating theatres. PATIENTS: 200 non-obese and 50 obese patients. MEASUREMENTS: During onset and offset of deep (post-tetanic-count 1-15 twitches), moderate (Train-of-Four-count 1-3 twitches) and shallow (Train-of-Four-ratio 0.01-1.0) depths of NMB were measured in obese and non-obese patients. The bias and limits of agreement of both devices were calculated using a Bland-Altman analysis for repeated measurements. Data obtained during spontaneous recovery (i.e. without the use of reversal agents) were used in the primary analyses. MAIN RESULTS: Data from enrolled patients yielded 942 paired post-tetanic-counts, 1175 paired train-of-four-counts and 1574 paired train-of-four ratios during spontaneous recovery. In non-obese patients, mean bias (95% CI) between the two devices was 3.405 (2.294 to 4.517) during deep NMB; -0.023 (-0.205 to 0.160) during moderate NMB and 0.312 (0.287 to 0.338) during shallow NMB. In obese patients, bias was -0.170 (-2.872 to 2.531); 0.178 (-0.202 to 0.558); 0.384 (0.299 to 0.469) for deep, moderate and shallow NMB respectively. CONCLUSIONS: There is variable disagreement between the level of NMB measured at the upper arm by compressomyography and at the adductor pollicis muscle measured by electromyography, throughout the various stages of NMB in obese and non-obese patients. Recovery of NMB on compressomyography preceded recovery on electromyography, which may have consequences for reversal and extubation decisions in clinical practice.

Cost and resource utilization in cervical cancer management: a real-world retrospective cost analysis.

OBJECTIVES: We set out to assess the health care resource utilization and cost of cervical cancer from the perspective of a single-payer health care system. METHODS: Retrospective observational data for women diagnosed with cervical cancer in British Columbia between 2004 and 2009 were analyzed to calculate patient-level resource utilization patterns from diagnosis to death or 5-year discharge. Domains of resource use within the scope of this cost analysis were chemotherapy, radiotherapy, and brachytherapy administered by the BC Cancer Agency; resource utilization related to hospitalization and outpatient visits as recorded by the B.C. Ministry of Health; medically required services billed under the B.C. Medical Services Plan; and prescriptions dispensed under British Columbia's health insurance programs. Unit costs were applied to radiotherapy and brachytherapy, producing per-patient costs. RESULTS: The mean cost per case of treating cervical cancer in British Columbia was $19,153 (standard error: $3,484). Inpatient hospitalizations, at 35%, represented the largest proportion of the total cost (95% confidence interval: 32.9% to 36.9%). Costs were compared for subgroups of the total cohort. CONCLUSIONS: As health care systems change the way they manage, screen for, and prevent cervical cancer, cost-effectiveness evaluations of the overall approach will require up-to-date data for resource utilization and costs. We provide information suitable for such a purpose and also identify factors that influence costs.

Improved diagnosis of childhood tuberculous meningitis using more than one nucleic acid amplification test.

BACKGROUND: Early treatment is critical to reducing tuberculous meningitis (TBM) related morbidity and mortality. Diagnosis based on cerebrospinal fluid (CSF) culture is impractical due to slow turnaround times, while microscopy has poor sensitivity. Enhanced detection methods are essential to guide early treatment initiation, especially in vulnerable young children. METHODS: We assessed the diagnostic accuracy of the GenoType(®) MTBDRplus and Xpert(®) MTB/RIF assays on CSF collected from paediatric meningitis suspects prospectively enrolled at Tygerberg Hospital, Cape Town, South Africa. Fluorescent auramine-O microscopy, liquid culture for Mycobacterium tuberculosis, GenoType and Xpert assays were performed on all CSF samples. RESULTS: Of 101 meningitis suspects, 55 were diagnosed with TBM and 46 served as non-TBM controls. Using a pre-defined TBM case definition as reference standard, sensitivities and specificities were 4% and 100% for fluorescent microscopy, 22% and 100% for culture, 33% and 98% for GenoType, 26% and 100% for Xpert, 22% and 100% for microscopy and culture combined and 49% and 98% for GenoType and Xpert combined. Culture, GenoType and Xpert combined performed best, with 56% sensitivity and 98% specificity. CONCLUSION: Although commercial nucleic-acid amplification tests performed on CSF revealed incrementally improved diagnostic accuracy, providing rapid microbiological confirmation, they cannot serve as a rule-out test.

inhA promoter mutations: a gateway to extensively drug-resistant tuberculosis in South Africa?

SETTING: Western Cape and Eastern Cape Provinces, South Africa. OBJECTIVE: To assess the potential association between the evolution of extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis and mutations in the inhA promoter or the katG gene. DESIGN: Analysis of the frequency distribution of isoniazid (INH) resistance conferring mutations in a population sample of drug-resistant isolates of M. tuberculosis. RESULTS: In the Western Cape and Eastern Cape Provinces, the percentage of isolates exhibiting inhA promoter mutations increased significantly from respectively 48.4% and 62.4% in multidrug-resistant tuberculosis (MDR-TB) isolates to 85.5% and 91.9% in XDR isolates. Data from the Western Cape revealed that significantly more XDR-TB isolates showed mutations in the inhA promoter than in katG (85.5% vs. 60.9%, P < 0.01), while the respective proportions were equal for INH-resistant non-MDR-TB isolates (∼30%). CONCLUSIONS: inhA promoter mutations are strongly associated with XDR-TB in South Africa. We suggest that this is due to the dual resistance to ethionamide and (low-dose) INH conferred by inhA promoter mutations. The use of molecular probe assays such as the GenoType® MTBDRplus assay, which allows the detection of inhA promoter mutations, could enable treatment regimens to be adjusted depending on the pharmacogenetic properties of the mutations detected.

Mycobacterial transport medium for routine culture of fine needle aspiration biopsies.

Fine needle aspiration biopsy (FNAB) offers a simple outpatient technique for specimen collection in child tuberculosis suspects with peripheral lymphadenopathy. To perform FNAB with mycobacterial culture on an outpatient basis requires use of a sterile transport medium to facilitate bedside inoculation, maintain organism viability and reduce contamination risk en route to the laboratory. The mycobacterial yield and time to positive culture following bedside inoculation into standard mycobacterial growth indicator tubes were compared with initial inoculation into an inexpensive "in-house" liquid growth medium. Of 150 FNAB performed, 57 (38%) cultured Mycobacterium tuberculosis complex. There was one case each with non-tuberculous mycobacteria and Mycobacterium bovis BCG; the remaining 55 being M tuberculosis. Results were concordant in 142 (94.7%) bedside and laboratory inoculation pairs. There was no significant difference in time to positive culture between bedside and laboratory inoculation (16.2 days (SD 0.87) vs 17.1 days (SD 0.85)). Provision of inexpensive specimen transport bottles and practical tuition in FNAB should improve cost-effective diagnosis of tuberculosis at the primary healthcare level.

'Loss of pigment epithelium-derived factor enables migration, invasion and metastatic spread of human melanoma'.

Pigment epithelium-derived factor (PEDF) is a multifunctional secreted glycoprotein that displays broad anti-tumor activity based on dual targeting of the tumor microenvironment (anti-angiogenic action) and the tumor cells (direct anti-tumor action). Here, we show that PEDF expression is high in melanocytes, but it is lost during malignant progression of human melanoma. Using a high-throughput analysis of the data from microarray studies of molecular profiling of human melanoma, we found that PEDF expression is lost in highly invasive melanomas. In paired cell lines established from the same lesion but representing the high and low extremes of malignant potential, abundant PEDF expression was restricted to the poorly aggressive counterparts. We used RNA interference to directly address the functional consequences of PEDF silencing. PEDF knockdown in poorly aggressive melanoma cell lines augmented migration, invasion and vasculogenic mimicry, which translated into an increased in vivo metastatic potential. PEDF interference also significantly enhanced the migratory and invasive capability of normal melanocytes and moderately increased their proliferative potential. Our results show that loss of PEDF enables melanoma cells to acquire an invasive phenotype and, therefore, modulation of this multifunctional factor could be critical for the malignant progression of human melanoma.

Melanoma progression, gene expression and DNA microarrays.

In recent years DNA microarray analyses of gene expression changes in melanoma have been employed in an effort to better understand the processes of disease progression. Typically, the samples assessed are taken directly from tissue biopsies of distinct clinical stages. Apart from noting a significant shift in gene expression at the transition from thin to thick primary lesions, surprisingly little else has been learned. Furthermore, experiments performed using cell cultures derived from distinct clinical stages have entirely failed to identify a consistent stage-specific gene expression signature. This review compares the two approaches, discusses what was learned about the molecular nature of melanoma progression, and considers why stage-specific gene expression may be more complicated than originally thought.

Discordance between mycobacterial interspersed repetitive-unit-variable-number tandem-repeat typing and IS6110 restriction fragment length polymorphism genotyping for analysis of Mycobacterium tuberculosis Beijing strains in a setting of high incidence of tuberculosis.

IS6110 restriction fragment length polymorphism (RFLP) genotyping is the most widely used genotyping method to study the epidemiology of Mycobacterium tuberculosis. However, due to the complexity of the IS6110 RFLP genotyping technique, and the interpretation of RFLP data, mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) genotyping has been proposed as the new genotyping standard. This study aimed to determine the discriminatory power of different MIRU-VNTR locus combinations relative to IS6110 RFLP genotyping, using a collection of Beijing genotype M. tuberculosis strains with a well-established phylogenetic history. Clustering, diversity index, clustering concordance, concordance among unique genotypes, and divergent and convergent evolution were calculated for seven combinations of 27 different MIRU-VNTR loci and compared to IS6110 RFLP results. Our results confirmed previous findings that MIRU-VNTR genotyping can be used to estimate the extent of recent or ongoing transmission. However, molecular epidemiological linking of cases varied significantly depending on the genotyping method used. We conclude that IS6110 RFLP and MIRU-VNTR loci evolve independently and at different rates, which leads to discordance between transmission chains predicted by the respective genotyping methods. Concordance between the two genotyping methods could be improved by the inclusion of genetic distance (GD) into the clustering formulae for some of the MIRU-VNTR loci combinations. In summary, our findings differ from previous reports, which may be explained by the fact that in settings of low tuberculosis incidence, the genetic distance between epidemiologically unrelated isolates was sufficient to define a strain using either marker, whereas in settings of high incidence, continuous evolution and persistence of strains revealed the weaknesses inherent to these markers.

Fluorometric assay for testing rifampin susceptibility of Mycobacterium tuberculosis complex.

The emergence and transmission of multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) have raised concern about diagnostic delay associated with culture-based drug susceptibility testing methods. The association between rifampin resistance and MDR-TB or XDR-TB makes it an important genetic marker for genotypic drug susceptibility testing. In this article, we describe the analysis of the physical properties of the rifampin resistance-determining region (RRDR) in the rpoB gene by high-resolution thermal melt analysis as a method for detecting rifampin resistance in Mycobacterium tuberculosis complex. The RRDR from the M. tuberculosis complex was amplified by PCR from DNA templates extracted from sputum cultures of M. tuberculosis or the laboratory strain (H37Rv) in the presence of a fluorescent DNA binding dye. Subsequent mixing of the amplification products from the respective sputum cultures and the laboratory strain and thermocycling allowed the formation of DNA duplexes. The thermal denaturation properties of these DNA duplexes were determined by measuring the derivative of the intensity of fluorescence at different temperatures. Analysis of DNA extracted from 153 sputum cultures showed a sensitivity of 98% and a specificity of 100% for the detection of rifampin resistance compared to the "gold standard" culture-based phenotyping method. No statistical difference was detected in the performance of the method when applied to crude DNA from 134 boiled cultures. This method, named "FAST-Rif" ("fluorometric assay for susceptibility testing of rifampin"), allowed the rapid, reliable, and easy detection of genotypic rifampin resistance as a marker for MDR-TB and XDR-TB.

Ovarian leukocyte distribution and cytokine/chemokine mRNA expression in follicular fluid cells in women with polycystic ovary syndrome.

BACKGROUND: Polycystic ovary syndrome (PCOS) affects 5-10% of reproductive-aged women and is commonly associated with anovulatory infertility. Leukocytes, together with granulosa cells, may contribute to the pathogenesis of PCOS via their ability to secrete an array of cytokines implicated in follicle growth. The aim of this study was to examine leukocyte subtypes in follicular phase ovaries and to quantify cytokine and chemokine mRNA expression in follicular fluid cells obtained at the time of oocyte retrieval before IVF in women with and without PCOS. METHODS: Ovaries were immunostained for various leukocyte markers [CD3, CD4, CD14, CD15, CD45, CD45RA, CD45RO, CD57 and major histocompatibility complex (MHC) class II]. In addition, follicular fluid cells were subjected to quantitative RT-PCR to evaluate colony-stimulating factor-1 (CSF-1), granulocyte-macrophage (GM)-CSF, interleukins (IL-1beta, IL-6, IL-8 and IL-10), monocyte chemotactic protein (MCP-1) and tumour necrosis factor (TNFalpha) mRNA expression relative to beta-actin. RESULTS: CD45RO+ cells (activated/memory T lymphocytes) were reduced by 60% in the theca layer of follicles from PCOS women. The relative abundance of macrophages and neutrophils was unchanged. Cytokine and chemokine mRNA transcripts examined were not affected by PCOS status. There was an association between high BMI and high TNFalpha and low IL-6 mRNA expression in follicular cells. IL-6 expression was higher in women who subsequently achieved pregnancy. CONCLUSIONS: T lymphocytes potentially play a role in the local pathological mechanisms of PCOS. Further studies are required to identify their contribution to the aetiology of this common condition.

Surface N balances and reactive N loss to the environment from global intensive agricultural production systems for the period 1970-2030.

Data for the historical years 1970 and 1995 and the FAO-Agriculture Towards 2030 projection are used to calculate N inputs (N fertilizer, animal manure, biological N fixation and atmospheric deposition) and the N export from the field in harvested crops and grass and grass consumption by grazing animals. In most industrialized countries we see a gradual increase of the overall N recovery of the intensive agricultural production systems over the whole 1970-2030 period. In contrast, low N input systems in many developing countries sustained low crop yields for many years but at the cost of soil fertility by depleting soil nutrient pools. In most developing countries the N recovery will increase in the coming decades by increasing efficiencies of N use in both crop and livestock production systems. The surface balance surplus of N is lost from the agricultural system via different pathways, including NH3 volatilization, denitrification, N(2)O and NO emissions, and nitrate leaching from the root zone. Global NH(3)-N emissions from fertilizer and animal manure application and stored manure increased from 18 to 34 Tg x yr(-1) between 1970 and 1995, and will further increase to 44 Tg x yr(-1) in 2030. Similar developments are seen for N(2)O-N (2.0 Tg x yr(-1) in 1970, 2.7 Tg x yr(-1) in 1995 and 3.5 Tg x yr(-1) in 2030) and NO-N emissions (1.1 Tg x yr(-1) in 1970,1.5 Tg x yr(-1) in 1995 and 2.0 Tg x yr(-1) in 2030).

Surface N balances and reactive N loss to the environment from global intensive agricultural production systems for the period 1970-2030.

Abstract Data for the historical years 1970 and 1995 and the FAO-Agriculture Towards 2030 projection are used to calculate N inputs (N fertilizer, animal manure, biological N fixation and atmospheric deposition) and the N export from the field in harvested crops and grass and grass consumption by grazing animals. In most industrialized countries we see a gradual increase of the overall N recovery of the intensive agricultural production systems over the whole 1970-2030 period. In contrast, low N input systems in many developing countries sustained low crop yields for many years but at the cost of soil fertility by depleting soil nutrient pools. In most developing countries the N recovery will increase in the coming decades by increasing efficiencies of N use in both crop and livestock production systems. The surface balance surplus of N is lost from the agricultural system via different pathways, including NH3 volatilization, denitrification, N20 and NO emissions, and nitrate leaching from the root zone. Global NH3-N emissions from fertilizer and animal manure application and stored manure increased from 18 to 34 Tg x yr(-1) between 1970 and 1995, and will further increase to 44 Tg x yr(-1) in 2030. Similar developments are seen for N2O-N (2.0 Tg x yr(-1) in 1970, 2.7 Tg x yr(-1) in 1995 and 3.5 Tg x yr(-1) in 2030) and NO-N emissions (1.1 Tg x yr(-1) in 1970, 1.5 Tg x yr(-1) in 1995 and 2.0 Tg x yr(-1) in 2030).

Imiquimod in basal cell carcinoma: how does it work?

Imiquimod is a topical immune response modifier that binds to Toll-like receptor-7 and -8, inducing interferon-alpha. We treated superficial basal cell carcinomas (BCC) with imiquimod 5% cream daily for 5-8 days. The BCC lesions were biopsied before treatment and following imiquimod treatment, when the lesion showed the signs of erosion. We applied histology, immunohistochemistry and gene array technology (Affymetrix) to gain further insight into the mode of action of imiquimod. Our findings demonstrate that imiquimod-induced BCC regression is associated with a strong activity of the innate immune response, mediated by cells of macrophage-monocyte origin and is associated with the induction of apoptosis.

Chatters on the Internet: a special target group for HIV prevention.

This study examined characteristics of men who use gay chat boxes on the Internet, including dating behaviour and sexual risk-taking with sex partners who were initially met through chatting. Men on chat boxes were asked to complete a brief questionnaire on the Internet. The questionnaire contained questions on demographics, chatting-related variables, and dating and risk-taking sexual behaviour. The results show that a large majority of the 190 respondents reported actual encounters as well as sex with men who were initially met through chatting. Almost 30% of the respondents who engaged in sex with chat dates reported inconsistent safe sexual behaviour. The level of unprotected sex increased as the number of sex partners who were met through chatting increased. These results suggest that chatters on the Internet may be a new target group for HIV prevention. Further study is needed to gain insight into the feasibility of prevention efforts for this target group.

Effects of leptin administration and feed restriction on thecal leucocytes in the preovulatory rat ovary and the effects of leptin on meiotic maturation, granulosa cell proliferation, steroid hormone and PGE2 release in cultured rat ovarian follicles.

Leptin is expressed by adipocytes and is thought to play a role in regulating food intake and in reproduction. It has been demonstrated that acute leptin administration to immature gonadotrophin-primed rats in vivo inhibits ovulation and causes a decline in food intake. However, feed restriction alone does not inhibit ovulation. Two experiments were designed to investigate the mechanism of leptin-induced inhibition of ovulation. In the first experiment, which was prompted by the importance of ovarian leucocytes in ovulation, the role of leucocytes in leptin-induced inhibition of ovulation was investigated. The second experiment investigated whether high leptin concentrations could inhibit other factors important to ovulation, such as meiotic competence of oocytes, granulosa cell proliferation, steroid or PGE(2) release, and interleukin 1beta production, in vitro. In the first experiment, the populations of neutrophils and monocytes-macrophages in the preovulatory follicles of gonadotrophin-primed, leptin-treated and -untreated rats were examined. A decrease in food intake, as a result of either leptin treatment or feed restriction, specifically reduced the numbers of neutrophils and monocytes-macrophages infiltrating the theca interna of preovulatory follicles without affecting the numbers found in the stroma. The findings show that reduced infiltration of thecal neutrophils and macrophages into preovulatory follicles is a response to reduced food intake. Furthermore, this reduction is not the direct cause of the leptin-induced inhibition of ovulation. In the second experiment, ovarian follicles were cultured for 4 or 12 h in the presence or absence of the following hormones: FSH (500 miu), insulin-like growth factor I (IGF-I) (50 ng ml(-1)), LH (100 ng ml(-1)) and leptin (300 ng ml(-1)). The results demonstrated that high concentrations of leptin in follicle culture do not affect meiotic maturation or steroid release, but tend to inhibit release of PGE 2 (although this result was not significant). DNA synthesis in granulosa cells was not inhibited by leptin in FSH- and IGF-I-supplemented culture media. These results are in agreement with previous studies that have shown that leptin inhibits the stimulatory effects of IGF-I on FSH-stimulated oestradiol production in rat granulosa cells without affecting progesterone production. In summary, leptin does not appear to have an adverse effect on the components of ovulation tested in this study, and therefore must impact on the ovulatory cascade in a way that remains to be defined.

Nitrogen efficiency in agriculture in Europe and India.

Nitrogen balance sheets are useful tools for studying the quantitative aspects of nutrients. Nitrogen balance sheets have been prepared for the animal production system, crop production system, and for the agricultural sector as a whole for all 15 member states of the European Union (EU15) and for the Indian subcontinent. The EU15 and India were chosen for this study on nitrogen efficiency using balance sheets because they each occupy roughly 300 million ha of land and use about 65 kg nitrogen fertiliser per hectare of agricultural land. Balance sheets were constructed for three systems: animal production, crop production, and the agricultural sector as a whole. In addition to detailed descriptions of the nitrogen balance sheets, brief recommendations for reducing nitrogen surpluses are also given. Surprisingly, the balance sheets for crop production and the agricultural sector as a whole showed a surplus of about 60 kg of nitrogen per hectare of agricultural land.

Binding of an RNA trafficking response element to heterogeneous nuclear ribonucleoproteins A1 and A2.

Heterogeneous nuclear ribonucleoprotein (hnRNP) A2 binds a 21-nucleotide myelin basic protein mRNA response element, the A2RE, and A2RE-like sequences in other localized mRNAs, and is a trans-acting factor in oligodendrocyte cytoplasmic RNA trafficking. Recombinant human hnRNPs A1 and A2 were used in a biosensor to explore interactions with A2RE and the cognate oligodeoxyribonucleotide. Both proteins have a single site that bound oligonucleotides with markedly different sequences but did not bind in the presence of heparin. Both also possess a second, specific site that bound only A2RE and was unaffected by heparin. hnRNP A2 bound A2RE in the latter site with a K(d) near 50 nm, whereas the K(d) for hnRNP A1 was above 10 microm. UV cross-linking assays led to a similar conclusion. Mutant A2RE sequences, that in earlier qualitative studies appeared not to bind hnRNP A2 or support RNA trafficking in oligodendrocytes, had dissociation constants above 5 microm for this protein. The two concatenated RNA recognition motifs (RRMs), but not the individual RRMs, mimicked the binding behavior of hnRNP A2. These data highlight the specificity of the interaction of A2RE with these hnRNPs and suggest that the sequence-specific A2RE-binding site on hnRNP A2 is formed by both RRMs acting in cis.