Cytokine exposure mediates transcriptional activation of the orphan nuclear receptor Nur77 in hematopoietic cells.

The orphan nuclear receptor Nur77 is an immediate-early response gene that based on tissue and cell context is implicated in a plethora of cellular processes, including proliferation, differentiation, apoptosis, metabolism, and inflammation. Nur77 has a ligand-binding pocket that is obstructed by hydrophobic side groups. Naturally occurring, cell-endogenous ligands have not been identified, and Nur77 transcriptional activity is thought to be regulated through posttranslational modification and modulation of protein levels. To determine whether Nur77 is transcriptionally active in hematopoietic cells in vivo, we used an upstream activating sequence (UAS)-GFP transgenic reporter. We found that Nur77 is transcriptionally inactive in vivo in hematopoietic cells under basal conditions, but that activation occurs following cytokine exposure by G-CSF or IL-3. We also identified a series of serine residues required for cytokine-dependent transactivation of Nur77. Moreover, a kinase inhibitor library screen and proximity labeling-based mass spectrometry identified overlapping kinase pathways that physically interacted with Nur77 and whose inhibition abrogated cytokine-induced activation of Nur77. We determined that transcriptional activation of Nur77 by G-CSF or IL-3 requires functional JAK and mTor signaling since their inhibition leads to Nur77 transcriptional inactivation. Thus, intracellular cytokine signaling networks appear to regulate Nur77 transcriptional activity in mouse hematopoietic cells.

RXRA DT448/9PP generates a dominant active variant capable of inducing maturation in acute myeloid leukemia cells.

RARA and RXRA contribute to myeloid maturation in both mice and humans, and deletion of Rxra and Rxrb augments leukemic growth in mice. While defining the domains of RXRA that are required for anti-leukemic effects in murine KMT2A-MLLT3 leukemia cells, we unexpectedly identified RXRA DT448/9PP as a constitutively active variant capable of inducing maturation and loss of their proliferative phenotype. RXRA DT448/9PP was associated with ligand-independent activity in reporter assays, with enhanced co-activator interactions, reduced engraftment in vivo, and activation of myeloid maturation transcriptional signatures that overlapped with those of cells treated with the potent RXRA agonist bexarotene, suggestive of constitutive activity that leads to leukemic maturation. Phenotypes of RXRA DT448/9PP appear to differ from those of two other RXRA mutations with forms of constitutive activity (F318A and S427F), in that DT448/9PP activity was resistant to mutations at critical ligand-interacting amino acids (R316A/L326A) and was resistant to pharmacological antagonists, suggesting it may be ligand-independent. These data provide further evidence that activated retinoid X receptors can regulate myeloid maturation and provide a novel constitutively active variant that may be germane for broader studies of retinoid X receptors in other settings.

Endogenous and combination retinoids are active in myelomonocytic leukemias.

Retinoid therapy transformed response and survival outcomes in acute promyelocytic leukemia (APL), but has demonstrated only modest activity in non-APL forms of acute myeloid leukemia (AML). The presence of natural retinoids in vivo could influence the efficacy of pharmacologic agonists and antagonists. We found that natural RXRA ligands, but not RARA ligands, were present in murine MLL-AF9-derived myelomonocytic leukemias in vivo and that the concurrent presence of receptors and ligands acted as tumor suppressors. Pharmacologic retinoid responses could be optimized by concurrent targeting RXR ligands (e.g. bexarotene) and RARA ligands (e.g. all-trans retinoic acid, ATRA), which induced either leukemic maturation or apoptosis depending on cell culture conditions. Co-repressor release from the RARA:RXRA heterodimer occurred with RARA activation, but not RXRA activation, providing an explanation for the combination synergy. Combination synergy could be replicated in additional, but not all, AML cell lines and primary samples, and was associated with improved survival in vivo, although tolerability of bexarotene administration in mice remained an issue. These data provide insight into the basal presence of natural retinoids in leukemias in vivo and a potential strategy for clinical retinoid combination regimens in leukemias beyond acute promyelocytic leukemia.

CDK1 and CDK2 regulate NICD1 turnover and the periodicity of the segmentation clock.

All vertebrates share a segmented body axis. Segments form from the rostral end of the presomitic mesoderm (PSM) with a periodicity that is regulated by the segmentation clock. The segmentation clock is a molecular oscillator that exhibits dynamic clock gene expression across the PSM with a periodicity that matches somite formation. Notch signalling is crucial to this process. Altering Notch intracellular domain (NICD) stability affects both the clock period and somite size. However, the mechanism by which NICD stability is regulated in this context is unclear. We identified a highly conserved site crucial for NICD recognition by the SCF E3 ligase, which targets NICD for degradation. We demonstrate both CDK1 and CDK2 can phosphorylate NICD in the domain where this crucial residue lies and that NICD levels vary in a cell cycle-dependent manner. Inhibiting CDK1 or CDK2 activity increases NICD levels both in vitro and in vivo, leading to a delay of clock gene oscillations and an increase in somite size.

The genome of a songbird.

The zebra finch is an important model organism in several fields with unique relevance to human neuroscience. Like other songbirds, the zebra finch communicates through learned vocalizations, an ability otherwise documented only in humans and a few other animals and lacking in the chicken-the only bird with a sequenced genome until now. Here we present a structural, functional and comparative analysis of the genome sequence of the zebra finch (Taeniopygia guttata), which is a songbird belonging to the large avian order Passeriformes. We find that the overall structures of the genomes are similar in zebra finch and chicken, but they differ in many intrachromosomal rearrangements, lineage-specific gene family expansions, the number of long-terminal-repeat-based retrotransposons, and mechanisms of sex chromosome dosage compensation. We show that song behaviour engages gene regulatory networks in the zebra finch brain, altering the expression of long non-coding RNAs, microRNAs, transcription factors and their targets. We also show evidence for rapid molecular evolution in the songbird lineage of genes that are regulated during song experience. These results indicate an active involvement of the genome in neural processes underlying vocal communication and identify potential genetic substrates for the evolution and regulation of this behaviour.

Current opinions and practices in post-stroke movement disorders: Survey of movement disorders society members.

BACKGROUND: Post-stroke movement disorders (PSMD) encompass a wide array of presentations, which vary in mode of onset, phenomenology, response to treatment, and natural history. There are no evidence-based guidelines on the diagnosis and treatment of PSMD. OBJECTIVES: To survey current opinions and practices on the diagnosis and treatment of PSMD. METHODS: A survey was developed by the PSMD Study Group, commissioned by the International Parkinson's and Movement Disorders Society (MDS). The survey, distributed to all members, yielded a total of 529 responses, 395 (74.7%) of which came from clinicians with experience with PSMD. RESULTS: Parkinsonism (68%), hemiballismus/hemichorea (61%), tremor (58%), and dystonia (54%) were by far the most commonly endorsed presentation of PSMD, although this varied by region. Basal ganglia stroke (76% of responders), symptoms contralateral to stroke (75%), and a temporal relationship (59%) were considered important factors for the diagnosis of PSMD. Oral medication use depended on the phenomenology of the PSMD. Almost 50% of respondents considered deep brain stimulation and ablative surgeries as options for treatment. The lack of guidelines for the diagnosis and treatment was considered the most important gap to address. CONCLUSIONS: Regionally varying opinions and practices on PSMD highlight gaps in (and mistranslation of) epidemiologic and therapeutic knowledge. Multicenter registries and prospective community-based studies are needed for the creation of evidence-based guidelines to inform the diagnosis and treatment of patients with PSMD.

A prospective newborn screening and treatment program for sickle cell anemia in Luanda, Angola.

Over 300,000 infants are born annually with sickle cell anemia (SCA) in sub-Saharan Africa, and >50% die young from infection or anemia, usually without diagnosis of SCA. Early identification by newborn screening (NBS), followed by simple interventions dramatically reduced the mortality of SCA in the United States, but this strategy is not yet established in Africa. We designed and implemented a proof-of-principle NBS and treatment program for SCA in Angola, with focus on capacity building and local ownership. Dried bloodspots from newborns were collected from five birthing centers. Hemoglobin identification was performed using isoelectric focusing; samples with abnormal hemoglobin patterns were analyzed by capillary electrophoresis. Infants with abnormal FS or FSC patterns were enrolled in a newborn clinic to initiate penicillin prophylaxis and receive education, pneumococcal immunization, and insecticide-treated bed nets. A total of 36,453 infants were screened with 77.31% FA, 21.03% FAS, 1.51% FS, and 0.019% FSC. A majority (54.3%) of affected infants were successfully contacted and brought to clinical care. Compliance in the newborn clinic was excellent (96.6%). Calculated first-year mortality rate for babies with SCA compares favorably to the national infant mortality rate (6.8 vs. 9.8%). The SCA burden is extremely high in Angola, but NBS is feasible. Capacity building and training provide local healthcare workers with skills needed for a functional screening program and clinic. Contact and retrieval of all affected SCA infants remains a challenge, but families are compliant with clinic appointments and treatment. Early mortality data suggest screening and early preventive care saves lives.

Secondary Hemophagocytic Lymphohistiocytosis Causing Hemorrhagic Encephalomyelitis and Spinal Subarachnoid Hemorrhage: A Case Report.

We are writing to present an interesting and novel case from our practice of a patient who presented with altered mental status and a rapidly progressive paraplegia as well as high fevers and pancytopenia. A bone marrow biopsy was diagnostic of hemophagocytic lymphohistiocytosis (HLH) and MRI showed hemorrhagic encephalitis and spinal subarachnoid hemorrhage. This case demonstrates the diverse neurological symptoms with which HLH presents, including spinal cord pathology. The astute neurologist should consider this diagnosis in the appropriate clinical context and diagnosis may require imaging to the complete neuraxis.

The Songbird Neurogenomics (SoNG) Initiative: community-based tools and strategies for study of brain gene function and evolution.

BACKGROUND: Songbirds hold great promise for biomedical, environmental and evolutionary research. A complete draft sequence of the zebra finch genome is imminent, yet a need remains for application of genomic resources within a research community traditionally focused on ethology and neurobiological methods. In response, we developed a core set of genomic tools and a novel collaborative strategy to probe gene expression in diverse songbird species and natural contexts. RESULTS: We end-sequenced cDNAs from zebra finch brain and incorporated additional sequences from community sources into a database of 86,784 high quality reads. These assembled into 31,658 non-redundant contigs and singletons, which we annotated via BLAST search of chicken and human databases. The results are publicly available in the ESTIMA:Songbird database. We produced a spotted cDNA microarray with 20,160 addresses representing 17,214 non-redundant products of an estimated 11,500-15,000 genes, validating it by analysis of immediate-early gene (zenk) gene activation following song exposure and by demonstrating effective cross hybridization to genomic DNAs of other songbird species in the Passerida Parvorder. Our assembly was also used in the design of the "Lund-zfa" Affymetrix array representing approximately 22,000 non-redundant sequences. When the two arrays were hybridized to cDNAs from the same set of male and female zebra finch brain samples, both arrays detected a common set of regulated transcripts with a Pearson correlation coefficient of 0.895. To stimulate use of these resources by the songbird research community and to maintain consistent technical standards, we devised a "Community Collaboration" mechanism whereby individual birdsong researchers develop experiments and provide tissues, but a single individual in the community is responsible for all RNA extractions, labelling and microarray hybridizations. CONCLUSION: Immediately, these results set the foundation for a coordinated set of 25 planned experiments by 16 research groups probing fundamental links between genome, brain, evolution and behavior in songbirds. Energetic application of genomic resources to research using songbirds should help illuminate how complex neural and behavioral traits emerge and evolve.

The Pediatric AIDS Corps: a 5-year evaluation.

BACKGROUND: The Baylor College of Medicine International Pediatric AIDS Initiative at Texas Children's Hospital created a global health corps named the Pediatric AIDS Corps (PAC) in June 2005. This report provides descriptive details and outputs for PAC over its first 5 years. METHODS: Demographic data were gathered about PAC physicians employed from July 2006 to June 2011. A 21-question survey was used to query PAC physicians about their experiences in the program. Data concerning clinical experiences and educational programs also were reviewed. RESULTS: A total of 128 physicians were employed with PAC. The median duration served was 22.7 months. Eighty-seven percent indicated that experience affected their future career choice, with half continuing to work with children and families living in resource-limited areas after they left PAC. Patient care was identified as the most rewarding part of their work (73%), whereas deaths (27%) were the most difficult. Baylor College of Medicine International Pediatric AIDS Initiative enrollment of HIV-infected children and adolescents into care and treatment increased from 6107 to 103 731 with the addition of PAC physicians. Approximately 500 local health care professionals per quarter benefited from HIV clinical attachments that were not available before PAC arrival. PAC physicians visited outreach sites providing in-depth HIV mentoring of local health care professionals, leading to 37% of the sites becoming self-sufficient. CONCLUSIONS: The positive evaluation by the PAC and the scale-up of clinical and educational programs support the recent calls for the development of a national global health corps program.

The Pediatric AIDS Corps: responding to the African HIV/AIDS health professional resource crisis.

Health professional capacity for delivery of HIV/AIDS care and treatment is severely constrained across sub-Saharan Africa. African health professional expertise in pediatrics is in particularly short supply. Here we describe a Pediatric AIDS Corps program that was designed to place pediatricians and other physicians in Africa on a long-term basis to expand existing health professional capacity for pediatric and family HIV/AIDS care and treatment. In the first 2 years of this program, 76 physicians were placed in 5 African countries that have been hit hard by HIV/AIDS. Enrollment of HIV-infected children in care more than quadrupled over a 24-month period, to 26 590. We believe that this pilot program can serve as a model for larger-scale efforts to immediately expand access for African children and families to life-saving HIV/AIDS care and treatment.

Education and preparation of physicians entering an international pediatric AIDS program: the Pediatric AIDS Corps.

The Pediatric AIDS Corps (PAC) are a group of physicians that were hired to provide clinical care and treatment to children and their families infected with HIV/AIDS and to help educate local health care professionals in the management of children with HIV/AIDS located in the high prevalence areas of sub-Saharan Africa. Prior to their departure the PAC were required to participate in a 4-week educational training program that included travel and tropical medicine and HIV infections in children, teaching skills, bioethics, and good clinical practice in human research training. Evaluation of the program was done using a 50-question pretest/posttest design, a standard postcourse evaluation, and a PAC focus group follow-up. Fifty-two physicians were hired who had been trained in the following specialties: pediatrics (77%), medicine/pediatrics (9%), family medicine (8%), and internal medicine (6%). Posttest scores improved by a mean of 10 points for all PAC physicians (p < 0.001) but those that had been in Africa for 5 months or more prior to the course continued to score higher than the other participants. Reviewing the results by category demonstrated significant improvement in all areas (p < or = 0.002) except for general pediatrics for the HIV/AIDS infected patients (p = 0.124) and psychosocial issues (p = 0.376). Changes for the next training were implemented based upon the information obtained from the PAC focus group. The foundation provided by this educational course was an important beginning for the PAC physicians. Other groups providing specialized care to patients in developing countries might consider a similar educational program.

Influence of institutionalization on time to HIV disease progression in a cohort of Romanian children and teens.

OBJECTIVES: The purpose of this work was to investigate the effect of institutionalization on death and CD4 decline in a cohort of 325 HIV-infected Romanian children. METHODS: A retrospective database analysis was conducted. Data from a nearly 3-year period were examined with Kaplan-Meier survival analysis and Cox regression analysis models. Subjects all received primary and HIV specialty care and treatment at the Romanian American Children's Center in Constanta, Romania. Children in one group resided with their biological families and the other children resided in "family home"-style institutions. RESULTS: There was no difference between groups for death during the follow-up period, although there was a trend for survival advantage for children in institutional care. There was no statistically significant difference between the study groups in terms of CD4 decline, although there was a trend toward greater decline among children who resided with their biological families. Children with their biological families were more likely to experience disease progression through either death or CD4 decline than were children in institutions. CONCLUSIONS: The family home-style institution may prove to be a replicable model for the safe and appropriate care of HIV-infected orphaned and abandoned children and teens.