Barriers, facilitators, and opportunities for Doctor of Nursing Practice engagement in translational research

BACKGROUND

Little is known about how Doctor of Nursing Practice (DNP) graduates apply translational research competencies in the practice setting.

PURPOSE

This qualitative descriptive study aimed to explore the barriers, facilitators, and opportunities for engaging in translational research among DNPs in practice.

METHODS

We conducted semi-structured interviews with 11 DNPs working within an 8-hospital health system from November 2020 through July 2021.

DISCUSSION

We identified four themes related to barriers (invisibility of the DNP degree and skillset; lack of role clarity and organizational structure for DNPs; lack of time for engagement in translational research; lack of support for engagement in translational research), one theme related to facilitators (encouragement from colleagues and supervisors), and two themes related to opportunities (DNP education promotes recognition of nurse role in translational research; DNPs are interested in role expansion to include translational research).

CONCLUSION

DNPs have the interest and training to engage in translational research but face structural barriers to doing so.

Quality of work-life among advanced practice nurses who manage care for patients with heart failure: The effect of resilience during the Covid-19 pandemic

Background Clinician burnout, stress and job dissatisfaction among Advance Practice Registered Nurses (APRNS) may have impacted work-related quality of life (WRQoL) during the COVID-19 pandemic. No studies describe burnout and resilience in APRNs who manage care for patients with HF. Objectives Among APRNs who manage care for patients with HF, study aims included: 1) Describe burnout and WRQoL levels; 2) Determine the relationship between burnout and WRQoL; 3) Examine whether resilience moderates the association between WRQoL and burnout.

METHODS

 An online survey of American Association of Heart Failure Nurses and the Heart Failure Society of America APRN members were queried.

INCLUSION CRITERIA

APRN's who practiced in ambulatory or inpatient cardiology settings at least 8 h weekly.

OUTCOMES MEASURED

Burnout, WRQoL, and resilience. Results Participants' (N = 101) mean age was 50 (±10) years and 93% identified as female. APRNs worked more than 42 h weekly and reported moderate levels of resilience, high levels of personal (M = 51.7, norm-referenced mean: 35.9) and work-related burnout (M = 50.1, norm-referenced mean: 33.0). Correlations between high levels of burnout and low WRQoL (r range: -0.74 - -0.39 -, p<.001) were found. Burnout moderated the relationships among resilience and WRQoL. Conclusion APRNs had high levels of burnout during the COVID-19 pandemic. Patient-related burnout was not high. Level of burnout influenced the relationships among resilience and WRQoL suggesting that burnout is from workplace and personal sources, and that level of resilience could not overcome the effect of burnout. Interventions are needed regarding systems changes to uplift and support our workforce.

Coronary artery and thoracic aorta calcification is inversely related to coronary flow reserve as measured by ⁸²Rb PET/CT in intermediate risk patients

BACKGROUND

The strength and nature of the relationship between myocardial perfusion imaging (MPI), coronary flow reserve (CFR), and coronary artery calcium (CAC) and thoracic aorta calcium (TAC) remain to be clarified.

METHODS

Dynamic rest-pharmacological stress (82)Rb positron emission tomography/computed tomography MPI with CFR, CAC, and TAC was performed in 75 patients (59 ± 13 years; F/M = 38/37) with intermediate risk of coronary artery disease.

RESULTS

A total of 29 (39%) patients had ischemic and 46 (61%) had normal MPI. CAC was correlated with TAC (ρ = 0.7; P < .001), and CFR was inversely related with CAC and TAC (ρ = -0.6 and -0.5; P < .001, respectively). By gender-specific univariate analysis, age (P = .001), CAC (P = .004), and CFR (P = .008) in males, but CFR (P = .0001), age (P = .002), and TAC (P = .01) in females were significant predictors of ischemic MPI. By multiple regression, the most potent predictor was CFR [odds ratio (OR) = 0.17, P = .01), followed by age (OR = 1.07, P = .02), gender (OR = 4.01, P = .03), and CAC (OR = 1.002, P = .9).

CONCLUSIONS

Combination of MPI, CFR, CAC, and TAC has complementary roles in intermediate risk patients.

Working conditions and masked hypertension

INTRODUCTION

Masked hypertension, i.e., normal clinic blood pressure but elevated blood pressure during normal daily activities as measured by ambulatory monitoring, is a common problem and a serious cardiovascular risk factor. Given previously reported associations between work stressors and ambulatory blood pressure, an inquiry into the relationship between work stressors and masked hypertension is warranted.

OBJECTIVE

To assess the relationship between working conditions and masked hypertension.

DESIGN

Cross-sectional study.

SETTING

Hospital and home care employers in New York City.

STUDY PARTICIPANTS

Forty-five male and 119 female hospital and home care employee volunteers wore an ambulatory blood pressure monitor during working hours.

MAIN OUTCOME MEASURES

Masked hypertension was defined as work systolic ambulatory blood pressure ≥135 mmHg or diastolic ambulatory blood pressure ≥85 mmHg, and casual blood pressure <140/90 mmHg with no use of antihypertensive medications. Associations between work stressors and masked hypertension were tested by multiple logistic regression.

RESULTS

Masked hypertension, observed in 24.0% of males and 17.6% of females with normal casual office obtained blood pressure, was associated with evening, night or rotating shiftwork (odds ratio (OR) 8.25, 95% confidence interval (CI) 2.11-40.31) and with the combination of job strain and effort-reward imbalance (OR 2.97, 95% CI 1.02-8.60) after controlling for age. Associations remained substantial, and statistically significant for shiftwork, after individual adjustment for each of 10 potential confounders. Masked hypertension was not associated with total weekly work hours.

CONCLUSIONS

Masked hypertension is a significant individual and public health concern. Additional research is needed to clarify the role of work-related risk factors in the development of masked hypertension, and to develop an appropriate clinical and public health strategy for diagnosis, treatment and prevention.

Comparison of the Pentax Airway Scope and McGrath Videolaryngoscope with the Macintosh laryngoscope in tracheal intubation by anaesthetists unfamiliar with videolaryngoscopes: a manikin study

Videolaryngoscopes are becoming widely available and have been suggested as a replacement for the Macintosh in cases of cervical instability or even for use in the first instance. There is limited existing data on the use of videoscopes by experienced anaesthetists who are inexperienced in the use of videoscopes. We used a manikin model to compare time to intubation between the Macintosh blade, Pentax Airway Scope and the McGrath videolaryngoscope in a simulated urgent intubation by 23 experienced anaesthetists with no prior experience in the use of these videoscopes. We also measured the number of attempts and success of intubation within three minutes. Ease of device use and laryngoscopic view obtained were also recorded. We found that all participants could intubate the manikin within three minutes, with a median of one attempt using the Pentax Airway Scope. Only 48% of participants (n=11) could intubate within three minutes using the McGrath videolaryngoscope and required a median of three attempts. This difference occurred despite the majority of anaesthetists obtaining a Grade 1 Cormack and Lehane view with both videoscopes. We demonstrated that anaesthetists who were naive to these videoscopes can successfully intubate the trachea using the Pentax Airway Scope but not the McGrath videolaryngoscope.

Lymphoscintigraphy and triangulated body marking for morbidity reduction during sentinel node biopsy in breast cancer

Current trends in patient care include the desire for minimizing invasiveness of procedures and interventions. This aim is reflected in the increasing utilization of sentinel lymph node biopsy, which results in a lower level of morbidity in breast cancer staging, in comparison to extensive conventional axillary dissection. Optimized lymphoscintigraphy with triangulated body marking is a clinical option that can further reduce morbidity, more than when a hand held gamma probe alone is utilized. Unfortunately it is often either overlooked or not fully understood, and thus not utilized. This results in the unnecessary loss of an opportunity to further reduce morbidity.

Optimized lymphoscintigraphy and triangulated body marking provides a detailed 3 dimensional map of the number and location of the sentinel nodes, available before the first incision is made. The number, location, relevance based on time/sequence of appearance of the nodes, all can influence 1) where the incision is made, 2) how extensive the dissection is, and 3) how many nodes are removed. In addition, complex patterns can arise from injections. These include prominent lymphatic channels, pseudo-sentinel nodes, echelon and reverse echelon nodes and even contamination, which are much more difficult to access with the probe only. With the detailed information provided by optimized lymphoscintigraphy and triangulated body marking, the surgeon can approach the axilla in a more enlightened fashion, in contrast to when the less informed probe only method is used. This allows for better planning, resulting in the best cosmetic effect and less trauma to the tissues, further reducing morbidity while maintaining adequate sampling of the sentinel node(s).

Using the intraoperative hand held probe without lymphoscintigraphy or using only dye correlates with higher sensory morbidity following sentinel lymph node biopsy in breast cancer: a review of the literature

BACKGROUND

There are no studies that have directly investigated the incremental reduction in sensory morbidity that lymphoscintigraphy images (LS) and triangulated body marking or other skin marking techniques provide during sentinel lymph node biopsy (SLNB) compared to using only the probe without LS and skin marking or using only dye. However, an indirect assessment of this potential for additional sensory morbidity reduction is possible by extracting morbidity data from studies comparing the morbidity of SLNB to that of axillary lymph node dissection.

METHODS

A literature search yielded 13 articles that had data on sensory morbidity at specific time points on pain, numbness or paresthesia from SLNB that used radiotracer and probe or used only dye as a primary method of finding the sentinel node (SN). Of these, 10 utilized LS, while 3 did not utilize LS. By matching the data in studies not employing LS to the studies that did, comparisons regarding the percentage of patients experiencing pain, numbness/paresthesia after SLNB could be reasonably attempted at a cutoff of 9 months.

RESULTS

In the 7 studies reporting on pain after 9 months (> 9 months) that used LS (1347 patients), 13.8% of patients reported these symptoms, while in the one study that did not use LS (143 patients), 28.7% of patients reported these symptoms at > 9 months (P < 0.0001). In the 6 studies reporting on numbness and/or paresthesia at > 9 months that used LS (601 patients), 12.5% of patients reported these symptoms, while in the 3 studies that did not use LS (229 patients), 23.1% of patients reported these symptoms at > 9 months (P = 0.0002). Similar trends were also noted for all these symptoms at < or = 9 months.

CONCLUSION

Because of variations in techniques and time of assessing morbidity, direct comparisons between studies are difficult. Nevertheless at a minimum, a clear trend is present: having the LS images and skin markings to assist during SLNB appears to yield more favorable morbidity outcomes for the patients compared to performing SLNB with only the probe or performing SLNB with dye alone. These results are extremely pertinent, as the main reason for performing SLNB itself in the first place is to achieve reduced morbidity.

Dietary supplementation with bean extract improves lipid profile in overweight and obese subjects

The aim of this study was to evaluate the long-term effects of a dietary supplementation of bean extract on serum lipids, nutritional parameters, and fat excretion in feces.Sixty-two overweight and obese (body mass index > 25 kg/m(2)) volunteers were randomized to receive the dietary supplement (n = 31, supplement group) or the placebo (n = 31, placebo group). There were 41 women and 21 men, ages 22 to 66 years. Two capsules of a dietary supplement or a placebo were administered three times daily for 3 mo. The supplement group was then invited to participate in an open-label study for 9 mo. Twenty-four subjects (7 men and 17 women) were randomized to receive two or four capsules of the supplement three times daily. Lipids and nutritional blood parameters were measured at baseline, after 3 mo, and at 12 mo. Excretion of fat in feces was measured. At 3 mo, reduction in serum concentration of cholesterol was found in the supplement group but not in the placebo group. High-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triacylglycerols in serum did not change in either group. In the 9-mo open-label study, no further reduction in serum cholesterol was observed. Low-density lipoprotein and the ratio of low- to high-density lipoprotein decreased, whereas triacylglycerols remained unchanged. Serum vitamin B12 and folic acid decreased but remained within the normal range. Ferritin and albumin in serum remained unchanged. No differences were observed in serum lipids and nutritional parameters between groups. The bean extract significantly increased fat excretion in feces. In conclusion, this dietary supplementation improved lipoprotein profile and enhanced fat excretion in feces in overweight and obese subjects.

Validation in the canine model of a new non-invasive method of measuring coronary blood flow reserve: split dose thallium-201 rest/stress imaging

Diffusely impaired coronary blood flow reserve is difficult to measure non-invasively. We developed and tested a quantitative non-invasive method of measuring coronary blood flow reserve using thallium-201 perfusion imaging. Ten anesthetized dogs were injected simultaneously at rest with thallium-201 and either Ru-103 or Sn-113 microspheres. SPECT images were obtained followed by varying doses of intravenous adenosine, and a second thallium-201 dose was injected simultaneously with either Nb-95 or Sc-46 microspheres. SPECT images were then repeated. The heart was removed, sectioned and counted, along with arterial blood samples. Blood flow was calculated at rest and stress. Peak resting counts in four regions in each of three SPECT slices were subtracted from stress values and stress/rest thallium-201 count ratios (coronary flow reserve (CFR)) were calculated and correlated with the corresponding microsphere flow ratios. Overall correlation of the imaging and microsphere flow ratios was 0.77 (p = 0.0001). Regional correlation coefficients ranged from 0.65-0.86 (p = 0.0001). Coronary blood flow reserve ratios by the microsphere method ranged from 0.7 to 5.3, and by thallium-201 imaging from 0.33-2.45. The non-invasively measured coronary blood flow reserve with thallium-201 imaging and adenosine stress correlates well with microsphere-measured coronary blood flow reserve over a wide range of coronary flows, and should be useful in clinical studies of CFR impairment.

Effect of long-term eprosartan versus enalapril antihypertensive therapy on left ventricular mass and coronary flow reserve in stage I-II hypertension. Eprosartan Study Group

A double-blind comparator study was performed in 528 hypertensive patients [baseline sitting diastolic blood pressure (SitDBP) 95-114 mmHg]. The primary objective was to compare the incidence of drug-related cough in patients treated with enalapril and eprosartan. This paper reports the results of 27 asymptomatic patients who were recruited into a single centre substudy of the multicentre trial and randomised to receive either eprosartan (200-300 mg b.i.d.) or enalapril (5-20 mg o.d.). Blood pressure (BP) reduction, left ventricular (LV) mass regression and change in coronary flow reserve (CFR) after 6 months' treatment with either eprosartan or enalapril were compared. At the end of the study, eprosartan and enalapril were found to have caused similar reductions in BP. There was an increase in CFR in the eprosartan group to 1.6 +/- 0.3 and a decrease in CFR in the enalapril group to 1.3 +/- 0.3. Neither value was significantly different from baseline although the difference between the two groups was significant (p = 0.05). By study endpoint, there was a significant reduction in LV mass in the enalapril group (p = 0.05), but not the eprosartan (p = ns) group. Further investigation of the effects of angiotensin receptor blockers on CFR and LV mass regression appear warranted.

C-erbB-3 in human breast carcinoma: expression and relation to prognosis and established prognostic indicators

A series of 346 patients with primary operable breast cancer and a series of 145 patients with advanced breast cancer were investigated for c-erbB-3 protein expression using the monoclonal antibody RTJ1. Formalin-fixed, paraffin-embedded tumour samples were stained using a standard immunochemical method and staining was assessed on a four-point scale. The study aimed to observe the expression of the c-erbB-3 protein and investigate any relationship between expression and established prognostic indicators and prognosis. In both the primary and advanced series breast tumour tissue was found to stain heterogeneously for c-erbB-3. The staining was observed to be predominantly cytoplasmic and the majority of tumours exhibited moderate positivity. However, 15% and 35% of cases in the primary operable and advanced series respectively displayed strong positive staining. No significant difference was found between the staining in the primary and advanced series. In the primary operable breast cancers, no significant associations were demonstrated with overall survival, disease-free interval, regional recurrence, the presence of distant metastases, age, menopausal status, oestrogen receptor status, histological grade, lymph node stage, vascular invasion and c-erbB-2 protein expression. However, a significant association was seen between the degree of c-erbB-3 immunoreactivity and both tumour size (P < 0.01) and tumour type prognostic group (P = 0.05). No overall association with local recurrence was seen when the four groups of c-erbB-3 expression were analysed (P = 0.12), but when those tumours showing no or weak staining were compared with those showing moderate and strong immunoreactivity it was seen that the latter were significantly more likely to develop local recurrence (P = 0.03). In the series of patients with advanced disease, no significant associations were demonstrated with survival, UICC criteria, age, menopausal status, oestrogen receptor status, histological grade, c-erbB-2 status or the presence of vascular invasion. In conclusion this study found variable expression of c-erbB-3 protein in human breast carcinoma and an association with some recognised prognostic factors in those patients with primary operable breast carcinoma. It seems, however, unlikely that c-erbB-3 protein expression will emerge as a powerful enough prognostic factor to be of value in clinical practice.

Purification of early-B-cell factor and characterization of its DNA-binding specificity

Early-B-cell factor (EBF) is a nuclear protein that recognizes a functionally important sequence in the promoter of the mb-1 gene. Like the mb-1 gene, which encodes an immunoglobulin-associated protein, EBF is specifically expressed in the early stages of B-lymphocyte differentiation. We purified EBF by sequence-specific DNA affinity chromatography and examined its biochemical properties and DNA-binding specificity. Crude nuclear extract and affinity-purified EBF generated protein-DNA complexes with the mb-1 promoter that were indistinguishable in electrophoretic mobility shift and DNase I footprint assays. Fractionation of affinity-purified EBF by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and renaturation of isolated polypeptides indicated that EBF DNA-binding activity could be reconstituted from polypeptides with molecular masses of 62 to 65 kDa. Gel filtration chromatography suggested that native EBF has a molecular mass of 140 kDa, if a globular shape of the protein is assumed. Thus, EBF appears to be a dimer with subunits of 62 to 65 kDa. To characterize the DNA-binding specificity of purified EBF, we performed two sets of experiments. First, we examined various mutant EBF-binding sites for interaction with purified EBF in an electrophoretic mobility shift assay. Second, we used oligonucleotides containing pairs of randomized bases in a binding-site selection and amplification experiments to determine a preferred sequence for DNA binding by EBF. Taken together, the results of these experiments indicated that EBF recognizes variations on the palindromic sequence 5'-ATTCCCNNGGGAAT, with an optimal spacer of 2 bp between the half-sites.

Cloning and functional characterization of early B-cell factor, a regulator of lymphocyte-specific gene expression

Early B-cell factor (EBF) was identified previously as a tissue-specific and differentiation stage-specific DNA-binding protein that participates in the regulation of the pre-B and B lymphocyte-specific mb-1 gene. Partial amino acid sequences obtained from purified EBF were used to isolate cDNA clones, which by multiple criteria encode EBF. The recombinant polypeptide formed sequence-specific complexes with the EBF-binding site in the mb-1 promoter. The cDNA hybridized to multiple transcripts in pre-B and B-cell lines, but transcripts were not detected at significant levels in plasmacytoma, T-cell, and nonlymphoid cell lines. Expression of recombinant EBF in transfected nonlymphoid cells strongly activated transcription from reporter plasmids containing functional EBF-binding sites. Analysis of DNA binding by deletion mutants of EBF identified an amino-terminal cysteine-rich DNA-binding domain lacking obvious sequence similarity to known transcription factors. DNA-binding assays with cotranslated wild-type and truncated forms of EBF indicated that the protein interacts with its site as a homodimer. Deletions delineated a carboxy-terminal dimerization region containing two repeats of 15 amino acids that show similarity with the dimerization domains of basic-helix-loop-helix proteins. Together, these data suggest that EBF represents a novel regulator of B lymphocyte-specific gene expression.

The membrane IgM-associated proteins MB-1 and Ig-beta are sufficient to promote surface expression of a partially functional B-cell antigen receptor in a nonlymphoid cell line

The B-cell antigen receptors consist of membrane immunoglobulins (mIgs) noncovalently associated with two accessory proteins, MB-1 and Ig-beta. We used transfection into a nonlymphoid cell line to test whether MB-1 and Ig-beta were sufficient to promote cell surface expression of mIgM capable of signal transduction. Expression of MB-1 and Ig-beta, but not MB-1 alone, allowed high-level surface expression of mIgM in the AtT20 endocrine cell line, which presumably lacks other B-cell-specific components. The reconstituted antigen receptor was capable of mediating some of the signaling reactions characteristic of mIgM in B lymphocytes. Crosslinking mIgM on transfected AtT20 cells stimulated tyrosine phosphorylation of MB-1 and Ig-beta and also increased the amount of phosphatidylinositol 3-kinase activity that could be precipitated with anti-phosphotyrosine antibodies. When total cell lysates were analyzed by anti-phosphotyrosine immunoblotting, however, no induced phosphorylation of more abundant proteins was detected. Moreover, crosslinking of the receptor in AtT20 cells did not stimulate inositol phospholipid breakdown. Thus, the transfected B-cell antigen receptor could initiate some signal transduction events but AtT20 cells may lack components required for other signaling events associated with mIgM.

Gene for lymphoid enhancer-binding factor 1 (LEF1) mapped to human chromosome 4 (q23-q25) and mouse chromosome 3 near Egf

LEF-1 is a 54-kDa nuclear protein that is expressed specifically in pre-B and T-cells. It binds to a functionally important site in the T-cell receptor alpha enhancer and contributes to maximal enhancer activity. LEF-1 is a member of a family of regulatory proteins that share homology with the high mobility group protein 1 (HMG1). The location of the LEF1 gene on human and mouse chromosomes was determined by Southern blot analysis of DNA from panels of interspecies somatic cell hybrids using a murine cDNA probe. Human-specific DNA fragments were detected in all somatic cell hybrids that retained the human chromosomal region 4cen-q31.2. Fluorescent in situ hybridization with two biotin-labeled overlapping human genomic cosmids revealed a specific hybridization signal at 4q23-q25. The homologous locus in the mouse was mapped to chromosome 3 by Southern analysis of rodent x mouse hybrid cell DNA. This chromosomal location was confirmed by the use of a restriction fragment length polymorphism (RFLP) in recombinant inbred mouse strains. The results of this RFLP analysis indicated that the mouse Lef-1 gene was closely linked to Pmv-39 and Egf and was likely placed between these loci, both of which were previously mapped to distal mouse chromosome 3. Our mapping results did not suggest involvement of this gene in previously mapped genetic disorders or in known neoplasia-associated translocation breakpoints.

Heterogeneously initiated transcription from the pre-B- and B-cell-specific mb-1 promoter: analysis of the requirement for upstream factor-binding sites and initiation site sequences

The mb-1 gene, encoding a membrane immunoglobulin-associated protein, is developmentally regulated and expressed specifically in pre-B and mature B lymphocytes. Analysis of the TATA-less mb-1 promoter indicated that it directs initiation of transcription from multiple sites. Promoter sequences between -68 and +70 conferred the correct pattern of cell type-specific transcription upon a heterologous gene. Two nuclear factor-binding sites that are important for promoter function were identified between -59 and -38. Both sites interacted with ubiquitous nuclear factors in vitro. One of these factors was identified as Sp1. Multimerized copies of both factor-binding sites augmented expression from a heterologous minimal promoter in both lymphoid and nonlymphoid cells, suggesting that additional mb-1 promoter sequences are involved in determining the correct cell type specificity. Analysis of the heterogeneity of transcription initiation indicated that a mutation which increased the distance between upstream sequences and the region of initiation resulted in the utilization of a novel set of initiation sites. Moreover, an insertion of a TATA element into the mb-1 promoter at -30 biased initiation of transcription to +1 but did not abolish the use of the other sites. Mutation of an initiator sequence homology encompassing one of the major initiation sites had only a minor effect on its utilization. From these data, we conclude that upstream factor-binding sites in the TATA-less mb-1 promoter define a region in which initiation of transcription occurs at multiple sites.

A novel lineage-specific nuclear factor regulates mb-1 gene transcription at the early stages of B cell differentiation

The mb-1 gene, which encodes a protein associated with membrane-bound antibody, is expressed only at the early stages of B cell differentiation. To gain insight into the mechanisms that underlie temporally regulated gene expression, we examined the mb-1 promoter region for interactions with cell type-specific DNA binding proteins. Here, we report the characterization of a novel nuclear factor that recognizes the mb-1 promoter. This DNA binding activity, termed Early B cell Factor, or EBF, is expressed in early stage B cells, but not in late stage B cells, T cells or non-lymphoid cells. EBF recognizes the nucleotide sequence 5'-CAAGGGAAT-3' in the mb-1 and major histocompatibility complex (MHC) class II A alpha d promoters. The binding of EBF to DNA was characterized by DNase I footprinting and by methylation interference analysis which indicated both major and minor groove contacts. The specificity of EBF binding is distinct from that of other nuclear factors expressed in hematopoietic cells. EBF appears to consist of at least two polypeptides of approximately 70-75 kDa and 80-85 kDa. The EBF binding site was important for maximal mb-1 promoter activity in early stage B cells. Moreover, the EBF binding site conferred correct lineage- and stage-specific transcriptional activity upon a heterologous promoter in a context-dependent manner. Thus, EBF appears to represent an important transcriptional regulator of B cell specific gene expression.

LEF-1, a gene encoding a lymphoid-specific protein with an HMG domain, regulates T-cell receptor alpha enhancer function [corrected]

Lymphoid-specific cDNA clones were isolated that encode a nuclear protein with homology to the chromosomal nonhistone protein HMG-1 and to putative regulators of cell specialization, including the mammalian testis-determining factor SRY and fungal mating-type proteins. The gene represented by the isolated cDNA clones, termed LEF-1 (lymphoid enhancer-binding factor 1), is developmentally regulated and expressed in pre-B and T lymphocytes but not in later-stage B cells or nonlymphoid tissues. Both endogenous and recombinant LEF-1 were shown to bind to a functionally important site in the T-cell antigen receptor (TCR) alpha enhancer. Maximal TCR alpha enhancer activity was found to parallel the cell type-specific expression pattern of LEF-1. Moreover, forced expression of recombinant LEF-1 in late stage B cells increases TCR alpha enhancer function. Taken together, these data suggest that LEF-1 is a regulatory participant in lymphocyte gene expression and differentiation.