Assessing work role strain, burnout, and job satisfaction among remotely piloted aircraft operators: the moderating role of unit social support.

Utilizing the Job Demands-Resources (JD-R) theory as a guiding framework, the current study examined the relationships between job demands (work role strain) and occupational outcomes (burnout and job satisfaction) and assessed how job resources (team member social support and leader social support) mitigated the impact of high job demands for U.S. Air Force remotely piloted aircraft (RPA) operators. A total of 905 active duty U.S. Air Force RPA operators participated in a web-based occupational health assessment. Study findings confirmed that work role strain proved to be strongly related to negative occupational outcomes - increased burnout and reduced job satisfaction. Compelling evidence emerged suggesting that boosting job resources (i.e., team member and leader social support) may be a promising point of intervention to mitigate negative occupational outcomes. By investigating ongoing job demands that result in a higher incidence of burnout and job dissatisfaction, as well as job resources that protect against burnout and job dissatisfaction, researchers and practitioners can continue to introduce supportive resources at crucial points to alleviate the adverse consequences of occupational stress and burnout. Applying the JD-R theory to these findings highlights the importance of job resources for RPA operators and other employees working in high-risk, high-demand career fields. Implications and future directions are discussed.

Sources of Stress and Psychological Health Outcomes for Remotely Piloted Aircraft Operators: A Comparison Across Career Fields and Major Commands.

INTRODUCTION: U.S. Air Force remotely piloted aircraft (RPA) operators perform a variety of around-the-clock global intelligence, surveillance, and reconnaissance (ISR) missions that are considered critical to operational effectiveness. The growing need for ISR operations has led to significant increases in operational tempo and workload, resulting in elevated operational stress, burnout, and psychological distress. These negative outcomes are linked to conditions such as long hours, low manning, lack of sleep, and communication issues. Through regular assessments and the implementation of additional resources (i.e., embedded health care providers), Air Force leadership is working to alleviate the stressors and maintain psychological well-being. Thus, the purpose of this study is to compare the levels of stress, and prevalence of burnout and psychological distress across RPA career fields within two major commands. MATERIALS AND METHODS: Assessments were completed by 571 RPA operators from 2 major commands: Air Force Special Operations Command (n = 158) and Air Combat Command (n = 413). RPA career fields included pilots (n = 331), sensor operators (n = 137), and intelligence operators (n = 103). RESULTS: Results revealed that high stress levels from an array of sources continue to result in increased risk of burnout and psychological distress for RPA operators. Several significant differences in sources of high stress across career fields and major commands are identified and discussed. CONCLUSIONS: Overall, the results of this study highlight specific problem areas unique to certain subsets of the RPA community in need of targeted intervention and clarify several avenues for future research.

Predictors and protective factors for suicide ideation across remotely piloted aircraft career fields.

The US Air Force remote warrior community comprises several career fields including remotely piloted aircraft pilots and intelligence, cyber, and sensor operators. The crews are responsible for working seamlessly together to provide 24/7 real-time intelligence, surveillance, and reconnaissance and precision-strike weapons capabilities for a wide range of global combat operations. Due to the rapid increase in global demands and operational tempo, there is growing concern from military leadership about the impact of operational stress on the health and psychological well-being of remote warriors. Previous assessments from 2011 and 2015 have demonstrated a significant increase in the reported rates of operators experiencing suicide ideation. The current study examined two protective factors expected to reduce the risk of suicide ideation - team member social support and leader social support. A total of 905 active duty remote warriors participated in occupational health assessments conducted in 2018. Risk factors for suicide ideation included being unmarried, worsening relationship problems, occupational burnout, and increased operational stress. Results indicated that team member and leader social support were significant protective factors for shift workers and those who reported being less likely to seek mental healthcare. Implications of the findings, intervention recommendations, and directions for future research are discussed.

State policies and practices in behavior supports for persons with intellectual and developmental disabilities in the United States: a national survey.

Providing effective behavioral supports to decrease challenging behavior and replace it with appropriate alternative skills is essential to meeting the needs of many individuals with intellectual and developmental disabilities (IDD). It is also necessary for fulfilling the requirements of Medicaid-funded individual support plans and is important for moral, ethical, and societal reasons. Unfortunately, there is no national standard for behavioral support practices or source of information on the status of behavior support policies, practices, and services for adults with IDD at either state or national levels. The collection of comprehensive data on state behavior support definitions, provider qualifications, training, and oversight requirements is a necessary starting point for the development of plans to address needed policy and practice changes. This survey is the first national assessment of state policies and practices regarding the definition and delivery of behavior support services to people with intellectual and developmental disabilities receiving publicly financed supports in the United States.

Gene delivery to the lung using protein/polyethylenimine/plasmid complexes.

Delivery of genes to the lung has enormous potential in a wide variety of illnesses, from lung cancer to genetic deficiency diseases. Many delivery systems have been utilized, each with its own advantages and limitations. Polyethylenimine is a polycation capable of binding and compacting DNA, enabling intravascular plasmid delivery to normal tissues in such a way that the plasmid can be expressed in a proportion of the exposed cells. We have developed a novel intravenous method to deliver small amounts of plasmid to lung tissue, using nontoxic quantities of polyethylenimine in combination with albumin (or other soluble proteins). Injection of 1 microg or less of plasmid resulted in highly efficient gene expression in lung interstitial and endothelial tissues (0.5 to 1 ng luciferase per microg plasmid DNA), while larger quantities of plasmid reduced relative gene expression. Using luciferase as a reporter gene, single injections had maximal gene expression between 24 and 48 h, with a rapid decline thereafter. In contrast to some other delivery systems, however, no inhibition of gene expression occurred during multiple rounds of plasmid administration through 20 days. As a result, this method may have useful applications in diseases that could benefit from recurrent therapeutic gene delivery.

Overexpression of BCL-X(L) underlies the molecular basis for resistance to staurosporine-induced apoptosis in PC-3 cells.

We have reported previously that among human prostate cancer cell lines LNCaP but not PC-3 cells undergo apoptosis after treatment with the protein kinase inhibitor staurosporine (STS). We have now further investigated this model to uncover the molecular mechanism causing resistance to STS-induced apoptosis in PC-3 cells. S-100 lysates of both cell lines showed biochemical changes typical of apoptosis after the addition of cytochrome c and dATP, suggesting that the postmitochondrial phase of apoptosis was intact. Upon addition of STS, the proapoptotic molecules Bax and Bad became predominantly mitochondrial in both cell lines. This, in turn, was followed by loss of mitochondrial transmembrane potential, translocation of cytochrome c to the cytosol, activation of caspase-9, -3, and -7, and cleavage of the apoptotic targets, DNA fragmentation factor and poly(ADP-ribose) polymerase, in LNCaP but not in PC-3 cells. Components of the mitochondrial permeability transition pore, adenine nucleotide transporter and voltage-dependent anion channel, were normally expressed in the correct subcellular fraction of both cell lines. Overexpression of the proapoptotic proteins Bax and Bad, fused to a green fluorescent protein but not of green fluorescent protein alone, induced apoptosis in >80% of PC-3 cells. These experiments suggested that a factor protecting the mitochondria of PC-3 cells mediates resistance to STS-induced apoptosis. A wide search among the antiapoptotic Bcl-2 family members was performed, and Bcl-X(L) was found to be overexpressed in PC-3 cells. Experiments down-regulating Bcl-X(L) expression by using the tyrosine kinase inhibitor genistein, sodium butyrate, or an antisense Bcl-X(L) oligonucleotide restored sensitivity to apoptosis in PC-3 cells. Thus, Bcl-X(L) overexpression is one of the mediators of resistance to STS-induced apoptosis in the prostate cancer cell line PC-3.

Aerosol delivery of robust polyethyleneimine-DNA complexes for gene therapy and genetic immunization.

Aerosol delivery of plasmid DNA to the lungs offers the possibility of direct application of gene preparations to pulmonary surfaces as a means of treating a variety of genetic pulmonary disorders. However, the process of jet nebulization rapidly degrades naked DNA, viral vectors, and many lipid-based formulations. While complexing DNA with cationic lipids has been shown to significantly stabilize plasmid DNA, losses of biological activity often occur during nebulization, severely limiting the efficiency of aerosol delivery of many such complexes. In conjunction with the design of aerosol delivery systems appropriate for DNA delivery, we have developed formulations using polyethyleneimine (PEI, a polycationic polymer) and DNA that result in a high level of pulmonary transfection (10- to 100-fold greater than many cationic lipids) and are stable during nebulization. In addition, these PEI-based formulations exhibit a high degree of specificity for the lungs. The properties of PEI-based formulations that make them resistant to nebulization and efficient as DNA delivery vectors for pulmonary sites have been investigated. Potential applications of this technology, including the use of aerosolized PEI-DNA for genetic immunization, are discussed.

Genetic immunization with lung-targeting macroaggregated polyethyleneimine-albumin conjugates elicits combined systemic and mucosal immune responses.

Genetic immunization is a novel form of vaccination in which transgenes are delivered into the host to produce the foreign protein within host cells. Although systemic immune responses have been relatively easy to induce by genetic immunization, the induction of regional and mucosal immunity has often been more challenging. To address the problem of eliciting mucosal immunity in the lung, we utilized macroaggregated albumin to target plasmid DNA to the lung. Macroaggregated albumin is trapped in the lung after i. v. injection, and it is routinely used in radiolabeled form as an imaging modality to evaluate pulmonary blood flow. To couple DNA to this targeting agent, polyethyleneimine (a polycation that binds DNA and enhances transfection) was conjugated to serum albumin, and the conjugate was aggregated by heating to produce particles of 25-100 microm. The resulting particles bound plasmid DNA avidly, and when injected i.v. in mice, the particles distributed in the peripheral lung tissue in the alveolar interstitium. Particle-bound luciferase plasmid transfected a variety of cell lines in vitro, and after i.v. injection, gene expression was detected exclusively in the lung. Using human growth hormone as the encoded foreign Ag for immunization, i.v. injection of the particle-bound plasmid elicited both pulmonary mucosal and systemic immune responses, whereas naked DNA injected either i.v. or i.m. elicited only systemic responses. Thus, particle-bound plasmid DNA may have utility for genetic immunization by intravascular delivery to the lung and potentially to other organs and tissues.

Triple helix formation: binding avidity of acridine-conjugated AG motif third strands containing natural, modified and surrogate bases opposed to pyrimidine interruptions in a polypurine target.

A critical issue for the general application of triple-helix-forming oligonucleotides (TFOs) as modulators of gene expression is the dramatically reduced binding of short TFOs to targets that contain one or two pyrimidines within an otherwise homopurine sequence. Such targets are often found in gene regulatory regions, which represent desirable sites for triple helix formation. Using intercalator-conjugated AG motif TFOs, we compared the efficacy and base selectivity of 13 different bases or base surrogates in opposition to pyrimidines and purines substituted into selected positions within a paradigm 15-base polypurine target sequence. We found that substitutions closer to the intercalator end of the TFO (positions 4-6) had a more deleterious effect on the dissociation constant (K d) than those farther away (position 11). Opposite T residues at position 11, 3-nitropyrrole or cytosine in the TFO provided adequate binding avidity for useful triplex formation (K ds of 55 and 110 nM, respectively). However, 3-nitropyrrole was more base selective than cytosine, binding to T >/=4 times better than to A, G or C. None of the TFOs tested showed avid binding when C residues were in position 11, although the 3-nitropyrrole-containing TFO bound with a K d of 200 nM, significantly better than the other designs. Molecular modeling showed that the 3-nitropyrrole.T:A triad is isomorphous with the A.A:T triad, and suggests novel parameters for evaluating new base triad designs.

Gene transfer by guanidinium-cholesterol: dioleoylphosphatidyl-ethanolamine liposome-DNA complexes in aerosol.

BACKGROUND: A major challenge of gene therapy is the efficient transfer of genes to cell sites where effective transfection can occur. The impact of jet nebulization on DNA structural and functional integrity has been problematic for the aerosol delivery of genes to pulmonary sites and remains a serious concern for this otherwise promising and noninvasive approach. METHODS: This study examined effects of cationic liposome-DNA formulation on both transfection efficiency (in vitro and in vivo) and jet nebulizer stability. The effects of nebulization and sonication on liposome-DNA particle size characteristics were examined. Electron microscopy of promising formulations was performed using several fixation methods. RESULTS: The cationic lipid bis-guanidinium-tren-cholesterol (BGTC), in combination with the neutral co-lipid dioleoylphosphatidylethanolamine (DOPE), was found to have a degree of stability adequate to permit effective gene delivery by the aerosol route. Optimal ratios of lipids and plasmid DNA were identified. Particle size analysis and ultrastructural studies revealed a remarkably homogeneous population of distinctly liposomal structures correlating with the highest levels of transfection efficiency and nebulizer stability. CONCLUSIONS: Optimizing gene delivery vectors for pulmonary aerosol delivery to respiratory sites must take into account factors other than transfection efficiency in vitro. Effects of liposome-DNA formulation on liposomal morphology (i.e. particle size, multilamellar structure) appear to be relevant to stability during aerosolization. These studies have allowed us to identify formulations that hold promise for successful clinical application of aerosol gene delivery.

Synthesis and biodistribution of R- and S-isomers of [18F]-fluoropropranolol, a lipophilic ligand for the beta-adrenergic receptor.

The S and R isomers of [18F]-fluoropropranolol (1-[1-fluoro-2-isopropylamino]-3-naphthalen-1-yloxy-propan-2 -ol) have been prepared by reductive alkylation of the appropriate aminoalcohols. The radiosynthesis provides a reasonable yield (approximately 25%) to give products of 99% enantiomeric excess and specific activities of 1-3 Ci/micromol. The dissociation constants for the beta2 adrenergic receptor are 0.5 and 2.5 nM for the S and the R isomers, respectively. The biodistribution data in rats show that uptake and egress of the tracer is rapid but that the result of blocking studies and the difference between the R and the S isomers suggest receptor-mediated uptake in receptor-rich tissue.

A 15-base acridine-conjugated oligodeoxynucleotide forms triplex DNA with its IL-2R alpha promoter target with greatly improved avidity.

Attachment of 6,9-diamino-2-methoxyacridine to the 5' end of a purine-rich oligodeoxynucleotide targeting a 15 bp oligopurine oligopyrimidine stretch in the promoter region of the interleukin-2 receptor alpha chain (IL-2R alpha) gene results in an approximately 500-fold increase in its triplex forming avidity as determined by both band shift assay and DMS footprinting (Kd lowered from 2.5 microM to 5 nM). This oligonucleotide participates in Mg(2+)-dependent three-stranded DNA formation in which it is oriented antiparallel relative to the purine strand of the target duplex as determined by acridine moiety sensitized photoreactivity with the target duplex DNA. The oligonucleotides used in these studies were synthesized with a 3-amino-2-hydroxypropyl group at the 3' end to protect against exonucleolytic degradation for future in vivo applications. The 3'-amino group underwent partial removal, probably during the NaOH deprotection step. Both the 3'-amino and the 3'-free forms of the oligo have the same binding avidity and specificity. The interaction of the third strand with its target is sequence specific and can be essentially abolished by a point G-->T transversion 4 bases away from the 3' end of the target oligopurine block or severely reduced by other mutations within the target duplex. Thus, the attachment of the acridine moiety to the 5' end of the oligonucleotide does not seem to substantially compromise the sequence specificity of binding. Additionally, the oligonucleotide composed of G and A nucleotides was found to be superior to the oligonucleotide containing G and T residues since the difference in avidity of binding to the same target site was 17-fold.

Sequence-specific binding and cleavage of duplex DNA by a radioiodinated, intercalator-linked, triplex-forming oligonucleotide.

Applications of oligodeoxynucleotides to modulate gene expression have been the subject of much recent research. We have sought to develop a method to permanently inactivate a gene, or potentially kill cells containing abnormal genes. In this report, we show that a DNA intercalator conjugated to a triplex-forming oligonucleotide can be labeled with an Auger electron emitting radioisotope, can cleave its duplex DNA target, and can specifically bind the target sequence contained in a total of 10 kilobases of irrelevant DNA.

Comparison of triple helix formation by polypurine versus polypyrimidine oligodeoxynucleotides when conjugated to a DNA intercalator.

Biological applications of triplex forming oligonucleotides will require the development of oligomers with high avidity and specificity. We examined the binding enhancement resulting from intercalator conjugation to both parallel design (polythymidine T15) and antiparallel design (polypurine AG15, for binding a 15 base pair polypurine-polypyrimidine sequence in the IL-2R alpha gene enhancer) oligomers under various ionic strength and temperature conditions. Oligonucleotides were conjugated through a urea link to 6,9 diamino-3-methoxy acridine (to give T15C and AG15C). Intercalator conjugation dramatically enhanced the specific triplex binding avidity (Kd = 5 nM for AG15C and 275 nM for T15C at 25 degrees C, compared to 2 microM for AG15 and > 50 microM for T15 at 25 degrees C), without detectable binding to an inappropriate target sequence. Surprisingly, triplex formation with AG15C occurred at lower Mg2+ concentrations than with T15C. AG15 and AG15C showed rapid Mg2+ dependent self association, but not T15C or T15. T15C triplex formation occurred rapidly (completion in less than 4 min), while AG15C bound to its target sequence more slowly over 20-24 h. Thus, binding constants in the low nanomolar range are now achievable with intercalator conjugated polypurine antiparallel binding oligonucleotides, a prerequisite for biological applications of such agents.

Studies with [11C]alprazolam: an agonist for the benzodiazepine receptor.

We have built a system for the synthesis of high specific activity carbon-11 alprazolam (Xanax), a high affinity agonist for the benzodiazepine receptor. The system produces 30-40 mCi of the compound with a specific activity of > 12,000 Ci per millimole. Using this compound we have performed PET studies on 6 normal subjects and studied the cerebral influx and efflux of the compound. The uptake in the brain was low, approx. 1% of the administered dose. However, the levels of the compound in the circulation at early time points are heavily affected by the specific activity of the tracer, i.e. when pharmacologically active doses are used as blocking doses the concentration of radioactive material is higher in the circulation and more material enters the brain. We attribute this to a depot effect where the compound is trapped in saturatable sites in an organ, probably the lungs, and is slowly released over time. In the presence of blocking doses of agonist, the compound washes out of the brain more quickly suggesting that some blockade of the receptors is occurring. However, the pharmacological activity of the compound does not permit the administration of enough material to ensure complete receptor blockade. The compound shows definite signs of acting as a receptor binding ligand but the unusual pharmacokinetics complicate the interpretation of the data.

Linkage structures strongly influence the binding cooperativity of DNA intercalators conjugated to triplex forming oligonucleotides.

Conjugation of DNA intercalators to triple helix forming oligodeoxynucleotides (ODN's) can enhance ODN binding properties and consequently their potential ability to modulate gene expression. To test the hypothesis that linkage structure could strongly influence the binding enhancement of intercalator conjugation with triplex forming ODN's, we have used a model system to investigate binding avidity of short oligomers conjugated to DNA intercalators through various linkages. Using a dA10.T10 target sequence imbedded in a 20 bp duplex, binding avidities of a T10 ODN joined to the DNA intercalator 6,9-diamino, 3-methoxy acridine (DAMA) by 8 different 5' linkages were measured using an electrophoretic mobility shift assay. Although unmodified T10 has a very limited capacity for stable binding under these conditions (apparent Kd > 250 microM at 4 degrees C), conjugation to DAMA using flexible linkers of certain lengths and chemical compositions greatly enhanced binding (Kd of 1 microM at 4 degrees C). Other linkers, however, modestly enhanced binding or had no effect on binding at all. Thus, the length, flexibility, and chemical composition of linker structures all substantially influence intercalator conjugated oligodeoxynucleotide binding avidity.

Synthesis and biological activity of 125I/127I-phenylboronic acid derivatives.

Three iodinated phenylboronic acids have been synthesized: 4-iodophenylboronic acid (2a), 3-(4-iodobenzenesulfonamido)phenylboronic acid (5a) and 3-(5-dimethylamino-6-iodo-1-naphthalenesulfonamido)phenylboronic acid (6a). The corresponding no-carrier-added 125I derivatives 2b, 5b and 6b have been prepared in good yield by selective displacement of the tributylstannyl group. Compound 6b was concentrated in vitro preferentially in HT-29 human colon carcinoma cells compared to V79 Chinese hamster lung fibroblasts and showed selective retention in PaCa-2 human pancreatic cancer cells grown as solid tumor xenografts in the nude mouse.

Mutation induction by 125iodoacetylproflavine, a DNA-intercalating agent, in human cells.

Survival and the induction of mutations at the hprt and tk loci were measured in TK6 human lymphoblastoid cells following treatment with the DNA-intercalating agent 125iodoacetylproflavine (125IAP). 125IAP was readily taken up into the cells, was localized to the nucleus, and was released rapidly following resuspension of the cells in fresh medium. Treatment with 125IAP for 24 h yielded a D0 of 110 decays/cell and an induced mutant fraction of 0.13 x 10(-6) per decay at the hprt locus and 0.4 x 10(-6) per decay at the tk locus. Molecular analyses of 125IAP-induced hprt mutants by Southern blot revealed a high proportion of large-scale changes at this locus. When these results are compared with those observed with 125IdUrd, 125IAP shows a reduced effectiveness per decay, related perhaps to the non-covalent nature of intercalator binding, resulting in reduced energy deposition in the DNA.

Synthesis and biological activity of the intercalating agent 3-acetamido-5-[123/125I]iodo-6-aminoacridine.

3-Acetamido-5-iodo-6-aminoacridine (3), a derivative of the known intercalating agent proflavine (3,6-diaminoacridine) (1) was synthesized, and no-carrier-added 123I and 125I labeled compounds prepared. Compound 3 was taken up by live cells and localized in the nucleus. The intracellular concentration of [125I]3 was 7-fold greater in human prostate carcinoma (PC-3) cells than in normal Chinese hamster lung fibroblast (V-79) cells.

Absence of preferential uptake of [125I]iododihydrorhodamine 123 by four human tumor xenografts.

The biodistribution of [125I]iododihydrorhodamine 123 has been studied over a 96-h period in four human tumor xenograft models: HT-29 colon adenocarcinoma, PC-3 prostate carcinoma, HT-1080 fibrosarcoma, and PaCa-2 pancreatic carcinoma. Elimination of radioactivity in the tumor-bearing nude mice was rapid during the first 24 h and slow thereafter. The lack of uptake in the thyroid indicated there was little, if any, deiodination of the molecule. Activity was found mainly in the liver and spleen. Accumulation of radioactivity was low in all four tumors examined. At 4 h postinjection, as well as at 24 and 48 h, however, the total radioactive content in each of the four tumors was directly proportional to the weight of the tumor sample. This correlation was independent of tumor type, route of injection (i.v./i.p.) or dose (1.2-6 microCi/mouse). This was not true for any of the normal tissues, suggesting that this accumulation may be governed by certain intrinsic characteristics of the cancers tested.