Associations among drug acquisition and use behaviors, psychosocial attributes, and opioid-involved overdoses.

AIMS: This study sought to develop and assess an exploratory model of how demographic and psychosocial attributes, and drug use or acquisition behaviors interact to affect opioid-involved overdoses. DESIGN: We conducted exploratory and confirmatory factor analysis (EFA/CFA) to identify a factor structure for ten drug acquisition and use behaviors. We then evaluated alternative structural equation models incorporating the identified factors, adding demographic and psychosocial attributes as predictors of past-year opioid overdose. SETTING AND PARTICIPANTS: We used interview data collected for two studies recruiting opioid-misusing participants receiving services from a community-based syringe services program. The first investigated current attitudes toward drug-checking (N = 150). The second was an RCT assessing a telehealth versus in-person medical appointment for opioid use disorder treatment referral (N = 270). MEASUREMENTS: Demographics included gender, age, race/ethnicity, education, and socioeconomic status. Psychosocial measures were homelessness, psychological distress, and trauma. Self-reported drug-related risk behaviors included using alone, having a new supplier, using opioids with benzodiazepines/alcohol, and preferring fentanyl. Past-year opioid-involved overdoses were dichotomized into experiencing none or any. FINDINGS: The EFA/CFA revealed a two-factor structure with one factor reflecting drug acquisition and the second drug use behaviors. The selected model (CFI = .984, TLI = .981, RMSEA = .024) accounted for 13.1% of overdose probability variance. A latent variable representing psychosocial attributes was indirectly associated with an increase in past-year overdose probability (ß = .234, p = .001), as mediated by the EFA/CFA identified latent variables: drug acquisition (ß = .683, p < .001) and drug use (ß = .567, p = .001). Drug use behaviors (ß = .287, p = .04) but not drug acquisition (ß = .105, p = .461) also had a significant, positive direct effect on past-year overdose. No demographic attributes were significant direct or indirect overdose predictors. CONCLUSIONS: Psychosocial attributes, particularly homelessness, increase the probability of an overdose through associations with risky drug acquisition and drug-using behaviors. Further research is needed to replicate these findings with populations at high-risk of an opioid-related overdose to assess generalizability and refine the metrics used to assess psychosocial characteristics.

Syringe service program-based telemedicine linkage to opioid use disorder treatment: protocol for the STAMINA randomized control trial.

BACKGROUND: A key strategy for mitigating the current opioid epidemic is expanded access to medications for treating opioid use disorder (MOUD). However, interventions developed to expand MOUD access have limited ability to engage opioid users at higher levels of overdose risk, such as those who inject opioids. This paper describes the study protocol for testing STAMINA (Syringe Service Telemedicine Access for Medication-assisted Intervention through NAvigation), an intervention that engages high-risk opioid users at community-based syringe service programs (SSP) and quickly links them to MOUD using a telemedicine platform. METHODS: This randomized control trial will be conducted at three SSP sites in Chicago. All participants will complete an initial assessment with a provider from a Federally Qualified Health Center who can prescribe or refer MOUD services as appropriate. The control arm will receive standard referral to treatment and the intervention arm will receive immediate telemedicine linkage to the provider and (depending on the type of MOUD prescribed) provided transportation to pick up their induction prescription (for buprenorphine or naltrexone) or attend their intake appointment (for methadone). We aim to recruit a total of 273 participants over two years to provide enough power to detect a difference in our primary outcome of MOUD treatment linkage. Secondary outcomes include treatment engagement, treatment retention, and non-MOUD opioid use. Data will be collected using structured interviews and saliva drug tests delivered at baseline, three months, and six months. Fixed and mixed effects generalized linear regression analyses and survival analysis will be conducted to compare the probabilities of a successful treatment linkage between the two arms, days retained in treatment, and post-baseline opioid and other drug use. DISCUSSION: If successful, STAMINA's telemedicine approach will significantly reduce the amount of time between SSP clients' initial indication of interest in the medication and treatment initiation. Facilitating this process will likely lead to stronger additional treatment- and recovery-oriented outcomes. This study is also timely given the need for more rigorous testing of telemedicine interventions in light of temporary regulatory changes that have occurred during the COVID-19 pandemic. TRIAL REGISTRATION: ClinicalTrials.gov (Clinical Trials ID: NCT04575324 and Protocol Number: 1138-0420). Registered 29 September 2020. The study protocol is also registered on the Open Science Framework (DOI 10.17605/OSF.IO/4853 M).

Designing and implementing an intervention for returning citizens living with substance use disorder: discovering the benefits of peer recovery coach involvement in pilot clinical trial decision-making.

Peer-facilitated services in behavioral health care remain underutilized within criminal justice-involved community organizations, and there is little guidance for how to best involve peer workers in behavioral health-focused research activities. This paper described lessons learned regarding implementation of peer recovery coaches (PRCs) as part of development and pilot research on Substance Use Programming for Person-Oriented Recovery and Treatment (SUPPORT), a peer-facilitated substance use disorder (SUD) intervention for returning citizens. Qualitative data were collected from learning meetings with key stakeholders and group interviews with SUPPORT clinical trial participants and PRCs. Transcripts were analyzed to identify key decisions made impacting the development, implementation, and/or revision of the SUPPORT intervention and pilot clinical trial protocols. Analysis demonstrated that PRC involvement drove many of the decisions made regarding modifications to the original intervention and trial protocols, while benefitting client-level interactions and by influencing the non-profit agency and its connection to stakeholders. Moreover, PRCs improved the research design by refining the incentive structure and data collection plans. PRC involvement also contributed to the development of more recovery-oriented resources and catering support services to the unique needs of justice-involved individuals. Discussed were the implications for the role of PRCs in justice-involved behavioral health research and treatment.

The career transition experiences of military Veterans: A qualitative study.

Transitioning out of a military career can be difficult and stressful for Veterans. The purpose of this study was to gain an in-depth understanding of the challenges and needs of career transitioning Veterans. Fifteen United States Veterans from a larger mixed methods research project completed a qualitative semi-structured interview regarding their career transition. Interview questions invited participants to define their transition experience, identify influential psychosocial factors, resources utilized or needed, what it meant to transition out of the military, role changes experienced, and how the participant had adapted to the transition. Emergent thematic analysis revealed 4 themes: 1) it is necessary to actively prepare for the transition; 2) a variety of factors impacted the military career transition process; 3) transitioning out of a military career equated to the loss of structure; and 4) the transition required Veterans to establish themselves outside of the military. Findings from this study identified barriers, desired assistance, and facilitators to the career transition process, which should be considered by those assisting transitioning Veterans and when developing transition-related resources. Continuing to expand on this knowledge will positively impact service members as they exit their military career.

Understanding the healthcare experiences and needs of African immigrants in the United States: a scoping review.

BACKGROUND: Africans immigrants in the United States are the least-studied immigrant group, despite the research and policy efforts to address health disparities within immigrant communities. Although their healthcare experiences and needs are unique, they are often included in the "black" category, along with other phenotypically-similar groups. This process makes utilizing research data to make critical healthcare decisions specifically targeting African immigrants, difficult. The purpose of this Scoping Review was to examine extant information about African immigrant health in the U.S., in order to develop lines of inquiry using the identified knowledge-gaps. METHODS: Literature published in the English language between 1980 and 2016 were reviewed in five stages: (1) identification of the question and (b) relevant studies, (c) screening, (d) data extraction and synthesis, and (e) results. Databases used included EBSCO, ProQuest, PubMed, and Google Scholar (hand-search). The articles were reviewed according to title and abstract, and studies deemed relevant were reviewed as full-text articles. Data was extracted from the selected articles using the inductive approach, which was based on the comprehensive reading and interpretive analysis of the organically emerging themes. Finally, the results from the selected articles were presented in a narrative format. RESULTS: Culture, religion, and spirituality were identified as intertwined key contributors to the healthcare experiences of African immigrants. In addition, lack of culturally-competent healthcare, distrust, and complexity, of the U.S. health system, and the exorbitant cost of care, were identified as major healthcare access barriers. CONCLUSION: Knowledge about African immigrant health in the U.S. is scarce, with available literature mainly focusing on databases, which make it difficult to identify African immigrants. To our knowledge, this is the first Scoping Review pertaining to the healthcare experiences and needs of African immigrants in the U.S.

Identifying Unreported Opioid Deaths Through Toxicology Data and Vital Records Linkage: Case Study in Marion County, Indiana, 2011-2016.

OBJECTIVES: To demonstrate the severity of undercounting opioid-involved deaths in a local jurisdiction with a high proportion of unspecified accidental poisoning deaths. METHODS: We matched toxicology data to vital records for all accidental poisoning deaths (n = 1238) in Marion County, Indiana, from January 2011 to December 2016. From vital records, we coded cases as opioid involved, specified other substance, or unspecified. We extracted toxicology data on opioid substances for unspecified cases, and we have reported corrected estimates of opioid-involved deaths after accounting for toxicology findings. RESULTS: Over a 6-year period, 57.7% of accidental overdose deaths were unspecified and 34.2% involved opioids. Toxicology data showed that 86.8% of unspecified cases tested positive for an opioid. Inclusion of toxicology results more than doubled the proportion of opioid-involved deaths, from 34.2% to 86.0%. CONCLUSIONS: Local jurisdictions may be undercounting opioid-involved overdose deaths to a considerable degree. Toxicology data can improve accuracy in identifying opioid-involved overdose deaths. Public Health Implications. Mandatory toxicology testing and enhanced training for local coroners on standards for death certificate reporting are needed to improve the accuracy of local monitoring of opioid-involved accidental overdose deaths.

Fostering Local Health Department and Health System Collaboration Through Case Conferences for At-Risk and Vulnerable Populations.

In case conferences, health care providers work together to identify and address patients' complex social and medical needs. Public health nurses from the local health department joined case conference teams at federally qualified health center primary care sites to foster cross-sector collaboration, integration, and mutual learning. Public health nurse participation resulted in frequent referrals to local health department services, greater awareness of public health capabilities, and potential policy interventions to address social determinants of health.

Effects of smoke-free air law on acute myocardial infarction hospitalization in Indianapolis and Marion County, Indiana.

BACKGROUND: A comprehensive smoke-free air law was enacted on June 1, 2012 in most of Marion County, Indiana, including all of the City of Indianapolis. We evaluated changes in acute myocardial infarction (AMI) admission rates in Indianapolis and Marion County before compared to after the law. METHODS: We collected AMI admissions from five Marion County hospitals between May 2007 and December 2014. We used Poisson regression to evaluate the overall effects of the law on monthly AMI hospitalizations, adjusting for month, seasonality, meteorology, air pollution, and hospital utilization. We tested the interactions between the law and AMI risk factors on monthly AMI admission rates to identify subpopulations for which the effects might be stronger. RESULTS: Monthly AMI admissions declined 20% (95% CI 14-25%) in Marion County and 25% (95% CI 20-29%) in Indianapolis after the law was implemented. We observed decreases among never (21%, 95% CI 13-29%), former (28%, 95% CI 21-34%), and current smokers (26%, 95% CI 11-38%); Medicaid beneficiaries (19%, 95% CI 9-29%) and non-beneficiaries (26%, 95% CI 20-31%). We observed decreases among those with a history of diabetes (Yes: 22%, 95% CI 14-29%; No: 25%, 95% CI 18-31%), congestive heart failure (Yes: 23%, 95% CI 16-30%; No: 24%, 95% CI 17-31%), and hypertension (Yes: 23%, 95% CI 17-28%: No: 26%, 95% CI 15-36%). CONCLUSIONS: We observed decreases in AMI admissions comparable with previous studies. We identified subpopulations who benefitted from the law, such as former and current smokers, and those without comorbidities such as congestive heart failure and hypertension.

Defining the external implementation context: an integrative systematic literature review.

BACKGROUND: Proper implementation of evidence-based interventions is necessary for their full impact to be realized. However, the majority of research to date has overlooked facilitators and barriers existing outside the boundaries of the implementing organization(s). Better understanding and measurement of the external implementation context would be particularly beneficial in light of complex health interventions that extend into and interact with the larger environment they are embedded within. We conducted a integrative systematic literature review to identify external context constructs likely to impact implementation of complex evidence-based interventions. METHODS: The review process was iterative due to our goal to inductively develop the identified constructs. Data collection occurred in four primary stages: (1) an initial set of key literature across disciplines was identified and used to inform (2) journal and (3) author searches that, in turn, informed the design of the final (4) database search. Additionally, (5) we conducted citation searches of relevant literature reviews identified in each stage. We carried out an inductive thematic content analysis with the goal of developing homogenous, well-defined, and mutually exclusive categories. RESULTS: We identified eight external context constructs: (1) professional influences, (2) political support, (3) social climate, (4) local infrastructure, (5) policy and legal climate, (6) relational climate, (7) target population, and (8) funding and economic climate. CONCLUSIONS: This is the first study to our knowledge to use a systematic review process to identify empirically observed external context factors documented to impact implementation. Comparison with four widely-utilized implementation frameworks supports the exhaustiveness of our review process. Future work should focus on the development of more stringent operationalization and measurement of these external constructs.

Lay responder naloxone access and Good Samaritan law compliance: postcard survey results from 20 Indiana counties.

BACKGROUND: To reduce fatal drug overdoses, two approaches many states have followed is to pass laws expanding naloxone access and Good Samaritan protections for lay persons with high likelihood to respond to an opioid overdose. Most prior research has examined attitudes and knowledge among lay responders in large metropolitan areas who actively use illicit substances. The present study addresses current gaps in knowledge related to this issue through an analysis of data collected from a broader group of lay responders who received naloxone kits from 20 local health departments across Indiana. METHODS: Postcard surveys were included inside naloxone kits distributed in 20 Indiana counties, for which 217 returned cards indicated the person completing it was a lay responder. The survey captured demographic information and experiences with overdose, including the use of 911 and knowledge about Good Samaritan protections. RESULTS: Few respondents had administered naloxone before, but approximately one third had witnessed a prior overdose and the majority knew someone who had died from one. Those who knew someone who had overdosed were more likely to have obtained naloxone for someone other than themselves. Also, persons with knowledge of Good Samaritan protections or who had previously used naloxone were significantly more likely to have indicated calling 911 at the scene of a previously witnessed overdose. Primary reasons for not calling 911 included fear of the police and the person who overdosed waking up on their own. CONCLUSIONS: Knowing someone who has had a fatal or non-fatal overdose appears to be a strong motivating factor for obtaining naloxone. Clarifying and strengthening Good Samaritan protections, educating lay persons about these protections, and working to improve police interactions with the public when they are called to an overdose scene are likely to improve implementation and outcomes of naloxone distribution and opioid-related Good Samaritan laws.

Error Sources and Distinctness of Materials Parameters Obtained by THz-Time Domain Spectroscopy Using an Example of Oxidized Engine Oil.

Gasoline engine oil (SAE 5W-20) was subjected to thermal oxidization (TO) for four periods of time (0 h, 48 h, 96 h and 144 h) and exposed to THz-time domain spectroscopy (TDS) measurement. Error contributions from various error sources, such as repeatability errors, assembly errors of the probe volume and errors caused by the TDS system were evaluated with respect to discernibility and significance of measurement results. The most significant error source was due to modifications of the TDS setup, causing errors in the range of 0.13% of the refractive index for samples with a refractive index around 1.467 and a probe volume length between 5 and 15 mm at 1 THz. The absorption coefficient error was in the range of 8.49% for an absorption around 0.6 cm−1. While the average of measurements taken with different setup configurations did not yield significant differences for different TO times, a single, fixed setup would be able to discern all investigated oil species across the entire frequency range of 0.5⁻2.5 THz. The absorption coefficient measurement showed greater discernibility than the measurement of the refractive index.

Erratum: Mendez Aller, M. et al. Error Sources and Distinctness of Materials Parameters Obtained by THz-Time Domain Spectroscopy Using an Example of Oxidized Engine Oil. Sensors. Sensors 2018, 18, 2087.

The authors wish to correct the affiliation of co-author Ali Mazin Abdul-Munaim, due to name changes of which he was unaware during his leave of absence. [...].

Permanent Housing Placement and Reentry to Services Among Family Recipients of Homelessness Prevention and Rapid Re-Housing Program (HPRP) Assistance.

The Homelessness Prevention and Rapid Re-Housing Program (HPRP) provided individuals and families who were either at-risk or currently experiencing homelessness with time-limited financial and housing support services. Evaluations of HPRP showed a high rate of family placement into permanent housing. However, little research has explored immediate and longitudinal outcomes for families enrolled in HPRP. Using Homeless Management Information System data from Indianapolis, Indiana, we examined demographic and program-related predictors of families entering permanent housing and their risk of reentry into homeless services following HPRP participation. The sample included 511 families who enrolled in the program from 2009 to 2012, with an average follow-up period of 4.5 years. We conducted analyses separately for Homelessness Prevention (HP) recipients (n = 357) and Rapid Re-Housing (RRH) recipients (n = 154). Results revealed that HP families were more likely to enter permanent housing if they: included adults who were older in age, were enrolled longer in the program, were provided rental arrear services and utility payments, and did not receive legal services. RRH families receiving rental assistance services had significantly greater odds of entering permanent housing. Among permanently housed families, at least one family member in 10.9% of HP recipients and 18.8% of RRH recipients reentered homeless services. HP families with younger children and one veteran family member were at increased risk of reentry to homelessness services. RRH recipients who did not receive moving cost services and had more children were at greater risk of reentry. Study findings suggest a need for future research on HP and RRH interventions that identify unique service needs among families who are experiencing housing instability or homelessness.

Complementary feature selection from alternative splicing events and gene expression for phenotype prediction.

MOTIVATION: A central task of bioinformatics is to develop sensitive and specific means of providing medical prognoses from biomarker patterns. Common methods to predict phenotypes in RNA-Seq datasets utilize machine learning algorithms trained via gene expression. Isoforms, however, generated from alternative splicing, may provide a novel and complementary set of transcripts for phenotype prediction. In contrast to gene expression, the number of isoforms increases significantly due to numerous alternative splicing patterns, resulting in a prioritization problem for many machine learning algorithms. This study identifies the empirically optimal methods of transcript quantification, feature engineering and filtering steps using phenotype prediction accuracy as a metric. At the same time, the complementary nature of gene and isoform data is analyzed and the feasibility of identifying isoforms as biomarker candidates is examined. RESULTS: Isoform features are complementary to gene features, providing non-redundant information and enhanced predictive power when prioritized and filtered. A univariate filtering algorithm, which selects up to the N highest ranking features for phenotype prediction is described and evaluated in this study. An empirical comparison of pipelines for isoform quantification is reported by performing cross-validation prediction tests with datasets from human non-small cell lung cancer (NSCLC) patients, human patients with chronic obstructive pulmonary disease (COPD) and amyotrophic lateral sclerosis (ALS) transgenic mice, each including samples of diseased and non-diseased phenotypes. AVAILABILITY AND IMPLEMENTATION: https://github.com/clabuzze/Phenotype-Prediction-Pipeline.git CONTACT: clabuzze@iastate.edu, antoniom@bc.edu, watsondk@musc.edu, andersonpe2@cofc.edu.

Induction of hematopoietic and endothelial cell program orchestrated by ETS transcription factor ER71/ETV2.

The ETS factor ETV2 (aka ER71) is essential for the generation of the blood and vascular system, as ETV2 deficiency leads to a complete block in blood and endothelial cell formation and embryonic lethality in the mouse. However, the ETV2-mediated gene regulatory network and signaling governing hematopoietic and endothelial cell development are poorly understood. Here, we map ETV2 global binding sites and carry out in vitro differentiation of embryonic stem cells, and germ line and conditional knockout mouse studies to uncover mechanisms involved in the hemangiogenic fate commitment from mesoderm. We show that ETV2 binds to enhancers that specify hematopoietic and endothelial cell lineages. We find that the hemangiogenic progenitor population in the developing embryo can be identified as FLK1(high)PDGFRα(-). Notably, these hemangiogenic progenitors are exclusively sensitive to ETV2-dependent FLK1 signaling. Importantly, ETV2 turns on other Ets genes, thereby establishing an ETS hierarchy. Consequently, the hematopoietic and endothelial cell program initiated by ETV2 is maintained partly by other ETS factors through an ETS switching mechanism. These findings highlight the critical role that transient ETV2 expression plays in the regulation of hematopoietic and endothelial cell lineage specification and stability.

Examining Fatal Opioid Overdoses in Marion County, Indiana.

Drug-related overdoses are now the leading injury-related death in the USA, and many of these deaths are associated with illicit opioids and prescription opiate pain medication. This study uses multiple sources of data to examine accidental opioid overdoses across 6 years, 2010 through 2015, in Marion County, IN, an urban jurisdiction in the USA. The primary sources of data are toxicology reports from the county coroner, which reveal that during this period, the most commonly detected opioid substance was heroin. During the study period, 918 deaths involved an opiod, and there were significant increases in accidental overdose deaths involving both heroin and fentanyl. In order to disentangle the nature and source of opioid overdose deaths, we also examine data from Indiana's prescription drug monitoring program and the law enforcement forensic services agency. Results suggest that there have been decreases in the number of opiate prescriptions dispensed and increases in law enforcement detection of both heroin and fentanyl. Consistent with recent literature, we suggest that increased regulation of prescription opiates reduced the likelihood of overdoses from these substances, but might have also had an iatrogenic effect of increasing deaths from heroin and fentanyl. We discuss several policy implications and recommendations for Indiana.

Housing First and harm reduction: a rapid review and document analysis of the US and Canadian open-access literature.

BACKGROUND: Housing First is an evidence-based practice intended to serve chronically homeless individuals with co-occurring serious mental illness and substance use disorders. Despite housing active substance users, harm reduction is an often-overlooked element during the Housing First implementation process in real-world settings. In this paper, we explore the representation of the Housing First model within the open-access scholarly literature as a potential contributing factor for this oversight. METHODS: We conducted a rapid review of the US and Canadian open-access Housing First literature. We followed a document analysis approach, to form an interpretation of the articles' content related to our primary research questions. RESULTS: A total of 55 articles on Housing First were included in the final analysis. Only 21 of these articles (38.1%) included explicit mention of harm reduction. Of the 34 articles that did not discuss harm reduction, 22 provided a description of the Housing First model indicating it does not require abstinence from substance use; however, descriptions did not all clearly indicate abstinence was not required beyond program entry. Additional Housing First descriptions focused on the low-barrier entry criteria and/or the intervention's client-centeredness. CONCLUSIONS: Our review demonstrated a lack of both explicit mention and informed discussion of harm reduction in the Housing First literature, which is likely contributing to the Housing First research-practice gap to some degree. Future Housing First literature should accurately explain the role of harm reduction when discussing it in the context of Housing First programming, and public agencies promoting Housing First uptake should provide resources for proper implementation and monitor program fidelity to prevent model drift.

Multivariate models from RNA-Seq SNVs yield candidate molecular targets for biomarker discovery: SNV-DA.

BACKGROUND: It has recently been shown that significant and accurate single nucleotide variants (SNVs) can be reliably called from RNA-Seq data. These may provide another source of features for multivariate predictive modeling of disease phenotype for the prioritization of candidate biomarkers. The continuous nature of SNV allele fraction features allows the concurrent investigation of several genomic phenomena, including allele specific expression, clonal expansion and/or deletion, and copy number variation. RESULTS: The proposed software pipeline and package, SNV Discriminant Analysis (SNV-DA), was applied on two RNA-Seq datasets with varying sample sizes sequenced at different depths: a dataset containing primary tumors from twenty patients with different disease outcomes in lung adenocarcinoma and a larger dataset of primary tumors representing two major breast cancer subtypes, estrogen receptor positive and triple negative. Predictive models were generated using the machine learning algorithm, sparse projections to latent structures discriminant analysis. Training sets composed of RNA-Seq SNV features limited to genomic regions of origin (e.g. exonic or intronic) and/or RNA-editing sites were shown to produce models with accurate predictive performances, were discriminant towards true label groupings, and were able to produce SNV rankings significantly different from than univariate tests. Furthermore, the utility of the proposed methodology is supported by its comparable performance to traditional models as well as the enrichment of selected SNVs located in genes previously associated with cancer and genes showing allele-specific expression. As proof of concept, we highlight the discovery of a previously unannotated intergenic locus that is associated with epigenetic regulatory marks in cancer and whose significant allele-specific expression is correlated with ER+ status; hereafter named ER+ associated hotspot (ERPAHS). CONCLUSION: The use of models from RNA-Seq SNVs to identify and prioritize candidate molecular targets for biomarker discovery is supported by the ability of the proposed method to produce significantly accurate predictive models that are discriminant towards true label groupings. Importantly, the proposed methodology allows investigation of mutations outside of exonic regions and identification of interesting expressed loci not included in traditional gene annotations. An implementation of the proposed methodology is provided that allows the user to specify SNV filtering criteria and cross-validation design during model creation and evaluation.

Fli1 acts downstream of Etv2 to govern cell survival and vascular homeostasis via positive autoregulation.

RATIONALE: Cardiovascular health depends on proper development and integrity of blood vessels. Ets variant 2 (Etv2), a member of the E26 transforming-specific family of transcription factors, is essential to initiate a transcriptional program leading to vascular morphogenesis in early mouse embryos. However, endothelial expression of the Etv2 gene ceases at midgestation; therefore, vascular development past this stage must continue independent of Etv2. OBJECTIVE: To identify molecular mechanisms underlying transcriptional regulation of vascular morphogenesis and homeostasis in the absence of Etv2. METHODS AND RESULTS: Using loss- and gain-of-function strategies and a series of molecular techniques, we identify Friend leukemia integration 1 (Fli1), another E26 transforming-specific family transcription factor, as a downstream target of Etv2. We demonstrate that Etv2 binds to conserved Ets-binding sites within the promoter region of the Fli1 gene and governs Fli1 expression. Importantly, in the absence of Etv2 at midgestation, binding of Etv2 at Ets-binding sites in the Fli1 promoter is replaced by Fli1 protein itself, sustaining expression of Fli1 as well as selective Etv2-regulated endothelial genes to promote endothelial cell survival and vascular integrity. Consistent with this, we report that Fli1 binds to the conserved Ets-binding sites within promoter and enhancer regions of other Etv2-regulated endothelial genes, including Tie2, to control their expression at and beyond midgestation. CONCLUSIONS: We have identified a novel positive feed-forward regulatory loop in which Etv2 activates expression of genes involved in vasculogenesis, including Fli1. Once the program is activated in early embryos, Fli1 then takes over to sustain the process in the absence of Etv2.