Differential impact of a dyskeratosis congenita mutation in TPP1 on mouse hematopoiesis and germline

A TPP1 mutation known to cause telomere shortening and bone marrow failure in humans recapitulates telomere loss but results in severe germline defects in mice without impacting murine hematopoiesis.

Telomerase extends chromosome ends in somatic and germline stem cells to ensure continued proliferation. Mutations in genes critical for telomerase function result in telomeropathies such as dyskeratosis congenita, frequently resulting in spontaneous bone marrow failure. A dyskeratosis congenita mutation in TPP1 (K170∆) that specifically compromises telomerase recruitment to telomeres is a valuable tool to evaluate telomerase-dependent telomere length maintenance in mice. We used CRISPR-Cas9 to generate a mouse knocked in for the equivalent of the TPP1 K170∆ mutation (TPP1 K82∆) and investigated both its hematopoietic and germline compartments in unprecedented detail. TPP1 K82∆ caused progressive telomere erosion with increasing generation number but did not induce steady-state hematopoietic defects. Strikingly, K82∆ caused mouse infertility, consistent with gross morphological defects in the testis and sperm, the appearance of dysfunctional seminiferous tubules, and a decrease in germ cells. Intriguingly, both TPP1 K82∆ mice and previously characterized telomerase knockout mice show no spontaneous bone marrow failure but rather succumb to infertility at steady-state. We speculate that telomere length maintenance contributes differently to the evolutionary fitness of humans and mice.

Therapeutic Targeting of Notch Signaling: From Cancer to Inflammatory Disorders

Over the past two decades, the Notch signaling pathway has been investigated as a therapeutic target for the treatment of cancers, and more recently in the context of immune and inflammatory disorders. Notch is an evolutionary conserved pathway found in all metazoans that is critical for proper embryonic development and for the postnatal maintenance of selected tissues. Through cell-to-cell contacts, Notch orchestrates cell fate decisions and differentiation in non-hematopoietic and hematopoietic cell types, regulates immune cell development, and is integral to shaping the amplitude as well as the quality of different types of immune responses. Depriving some cancer types of Notch signals has been shown in preclinical studies to stunt tumor growth, consistent with an oncogenic function of Notch signaling. In addition, therapeutically antagonizing Notch signals showed preclinical potential to prevent or reverse inflammatory disorders, including autoimmune diseases, allergic inflammation and immune complications of life-saving procedures such allogeneic bone marrow and solid organ transplantation (graft-versus-host disease and graft rejection). In this review, we discuss some of these unique approaches, along with the successes and challenges encountered so far to target Notch signaling in preclinical and early clinical studies. Our goal is to emphasize lessons learned to provide guidance about emerging strategies of Notch-based therapeutics that could be deployed safely and efficiently in patients with immune and inflammatory disorders.

TPP1 mutagenesis screens unravel shelterin interfaces and functions in hematopoiesis

Telomerase catalyzes chromosome end replication in stem cells and other long-lived cells. Mutations in telomerase or telomere-related genes result in diseases known as telomeropathies. Telomerase is recruited to chromosome ends by the ACD/TPP1 protein (TPP1 hereafter), a component of the shelterin complex that protects chromosome ends from unwanted end joining. TPP1 facilitates end protection by binding shelterin proteins POT1 and TIN2. TPP1 variants have been associated with telomeropathies but remain poorly characterized in vivo. Disease variants and mutagenesis scans provide efficient avenues to interrogate the distinct physiological roles of TPP1. Here, we conduct mutagenesis in the TIN2- and POT1-binding domains of TPP1 to discover mutations that dissect TPP1's functions. Our results extend current structural data to reveal that the TPP1-TIN2 interface is more extensive than previously thought and highlight the robustness of the POT1-TPP1 interface. Introduction of separation-of-function mutants alongside known TPP1 telomeropathy mutations in mouse hematopoietic stem cells (mHSCs) lacking endogenous TPP1 demonstrated a clear phenotypic demarcation. TIN2- and POT1-binding mutants were unable to rescue mHSC failure resulting from end deprotection. In contrast, TPP1 telomeropathy mutations sustained mHSC viability, consistent with their selectively impacting end replication. These results highlight the power of scanning mutagenesis in revealing structural interfaces and dissecting multifunctional genes.

The Sec1/Munc18 protein Vps45 holds the Qa-SNARE Tlg2 in an open conformation

Fusion of intracellular trafficking vesicles is mediated by the assembly of SNARE proteins into membrane-bridging complexes. SNARE-mediated membrane fusion requires Sec1/Munc18-family (SM) proteins, SNARE chaperones that can function as templates to catalyze SNARE complex assembly. Paradoxically, the SM protein Munc18-1 traps the Qa-SNARE protein syntaxin-1 in an autoinhibited closed conformation. Here we present the structure of a second SM-Qa-SNARE complex, Vps45-Tlg2. Strikingly, Vps45 holds Tlg2 in an open conformation, with its SNARE motif disengaged from its Habc domain and its linker region unfolded. The domain 3a helical hairpin of Vps45 is unfurled, exposing the presumptive R-SNARE binding site to allow template complex formation. Although Tlg2 has a pronounced tendency to form homo-tetramers, Vps45 can rescue Tlg2 tetramers into stoichiometric Vps45-Tlg2 complexes. Our findings demonstrate that SM proteins can engage Qa-SNAREs using at least two different modes, one in which the SNARE is closed and one in which it is open.

Contamination in complex healthcare trials: the falls in care homes (FinCH) study experience

Background

Trials are at risk of contamination bias which can occur when participants in the control group are inadvertently exposed to the intervention. This is a particular risk in rehabilitation studies where it is easy for trial interventions to be either intentionally or inadvertently adopted in control settings. The Falls in Care Homes (FinCH) trial is used in this paper as an example of a large randomised controlled trial of a complex intervention to explore the potential risks of contamination bias. We outline the FinCH trial design, present the potential risks from contamination bias, and the strategies used in the design of the trial to minimise or mitigate against this. The FinCH trial was a multi-centre randomised controlled trial, with embedded process evaluation, which evaluated whether systematic training in the use of the Guide to Action Tool for Care Homes reduced falls in care home residents.

Data were collected from a number of sources to explore contamination in the FinCH trial. Where specific procedures were adopted to reduce risk of, or mitigate against, contamination, this was recorded. Data were collected from study e-mails, meetings with clinicians, research assistant and clinician network communications, and an embedded process evaluation in six intervention care homes.

During the FinCH trial, there were six new falls prevention initiatives implemented outside the study which could have contaminated our intervention and findings. Methods used to minimise contamination were: cluster randomisation at the level of care home; engagement with the clinical community to highlight the risks of early adoption; establishing local collaborators in each site familiar with the local context; signing agreements with NHS falls specialists that they would maintain confidentiality regarding details of the intervention; opening additional research sites; and by raising awareness about the importance of contamination in research among participants.

Conclusion

Complex rehabilitation trials are at risk of contamination bias. The potential for contamination bias in studies can be minimized by strengthening collaboration and dialogue with the clinical community. Researchers should recognise that clinicians may contaminate a study through lack of research expertise.

Multiscale analyses reveal native-like lamellar bone repair and near perfect bone-contact with porous strontium-loaded bioactive glass

The efficient healing of critical-sized bone defects using synthetic biomaterial-based strategies is promising but remains challenging as it requires the development of biomaterials that combine a 3D porous architecture and a robust biological activity. Bioactive glasses (BGs) are attractive candidates as they stimulate a biological response that favors osteogenesis and vascularization, but amorphous 3D porous BGs are difficult to produce because conventional compositions crystallize during processing. Here, we rationally designed a porous, strontium-releasing, bioactive glass-based scaffold (pSrBG) whose composition was tailored to deliver strontium and whose properties were optimized to retain an amorphous phase, induce tissue infiltration and encourage bone formation. The hypothesis was that it would allow the repair of a critical-sized defect in an ovine model with newly-formed bone exhibiting physiological matrix composition and structural architecture. Histological and histomorphometric analyses combined with indentation testing showed pSrBG encouraged near perfect bone-to-material contact and the formation of well-organized lamellar bone. Analysis of bone quality by a combination of Raman spectral imaging, small-angle X-ray scattering, X-ray fluorescence and focused ion beam-scanning electron microscopy demonstrated that the repaired tissue was akin to that of normal, healthy bone, and incorporated small amounts of strontium in the newly formed bone mineral. These data show the potential of pSrBG to induce an efficient repair of critical-sized bone defects and establish the importance of thorough multi-scale characterization in assessing biomaterial outcomes in large animal models.

The efficacy of PD-L1 blockade on PD-L1 negative medulloblastoma is dependent on timing and the tumor microenvironment

PD-L1 blockade has shown great success in the rejection of specific PD-L1+ tumor-types within various tissues. Blocking PD-L1 interactions with PD-1 molecules expressed on effector T cells allow them to engage their targets unimpeded and enhances tumor rejections. However, most pediatric tumors and some adult tumors express low to no surface PD-L1. Interestingly, some reports have demonstrated the rejection of PD-L1 negative tumors after treatment with anti-PD-L1 antibodies (Abs). When we administered anti-PD-L1 Abs 7 days after injection of CRISPR-negative PD-L1 (crPD-L1neg) medulloblastoma (MM1) tumors, all tumors were rejected. However, treating with anti-PD-L1 Abs at the time of tumor inoculation (day 0), resulted in a greatly diminished response to further treatment and a loss of protection. In addition, analysis of day 7 treated tumors in comparison to isotype and day 0 treated tumors, revealed an ~4- and ~2-fold increase in PD-1+ CD8+ T cells by day 21, respectively. These data suggest that the efficacy of anti-PD-L1 Abs on PD-L1 negative tumors is dependent on the timing and the microenvironment in which the T cell priming occurs. Our lab is investigating this phenomenon by interrogating the interaction of DC-T cell priming in the tumor draining lymph nodes (TDLNs) during the early stages of tumor growth. These studies may lead to improved efficacy of immune checkpoint blockade in PD-L1 negative tumors.

Positively selected enhancer elements endow osteosarcoma cells with metastatic competence

Metastasis results from a complex set of traits acquired by tumor cells, distinct from those necessary for tumorigenesis. Here, we investigate the contribution of enhancer elements to the metastatic phenotype of osteosarcoma. Through epigenomic profiling, we identify substantial differences in enhancer activity between primary and metastatic human tumors and between near isogenic pairs of highly lung metastatic and nonmetastatic osteosarcoma cell lines. We term these regions metastatic variant enhancer loci (Met-VELs). Met-VELs drive coordinated waves of gene expression during metastatic colonization of the lung. Met-VELs cluster nonrandomly in the genome, indicating that activity of these enhancers and expression of their associated gene targets are positively selected. As evidence of this causal association, osteosarcoma lung metastasis is inhibited by global interruptions of Met-VEL-associated gene expression via pharmacologic BET inhibition, by knockdown of AP-1 transcription factors that occupy Met-VELs, and by knockdown or functional inhibition of individual genes activated by Met-VELs, such as that encoding coagulation factor III/tissue factor (F3). We further show that genetic deletion of a single Met-VEL at the F3 locus blocks metastatic cell outgrowth in the lung. These findings indicate that Met-VELs and the genes they regulate play a functional role in metastasis and may be suitable targets for antimetastatic therapies.

CCL3 augments tumor rejection and enhances CD8+ T cell infiltration through NK and CD103+ dendritic cell recruitment via IFNγ

Inflammatory chemokines are critical contributors in attracting relevant immune cells to the tumor microenvironment and driving cellular interactions and molecular signaling cascades that dictate the ultimate outcome of host anti-tumor immune response. Therefore, rational application of chemokines in a spatial-temporal dependent manner may constitute an attractive adjuvant in immunotherapeutic approaches against cancer. Existing data suggest that the macrophage inflammatory protein (MIP)-1 family and related proteins, consisting of CCL3 (MIP-1α), CCL4 (MIP-1β), and CCL5 (RANTES), can be major determinant of immune cellular infiltration in certain tumors through their direct recruitment of antigen presenting cells, including dendritic cells (DCs) to the tumor site. In this study, we examined how CCL3 in a murine colon tumor microenvironment, CT26, enhances antitumor immunity. We identified natural killer (NK) cells as a major lymphocyte subtype that is preferentially recruited to the CCL3-rich tumor site. NK cells contribute to the overall IFNγ content, CD103⁺ DC accumulation, and augment the production of chemokines CXCL9 and CXCL10 for enhanced T cell recruitment. We further demonstrate that both soluble CCL3 and CCL3-secreting irradiated tumor vaccine can effectively halt the progression of established tumors in a spatial-dependent manner. Our finding implies an important contribution of NK in the CCL3 - CD103⁺ DC - CXCL9/10 signaling axis in determining tumor immune landscape within the tumor microenvironment.

CCL3 Enhances Antitumor Immune Priming in the Lymph Node via IFNγ with Dependency on Natural Killer Cells

Lymph node (LN) plays a critical role in tumor cell survival outside of the primary tumor sites and dictates overall clinical response in many tumor types (1, 2). Previously, we and others have demonstrated that CCL3 plays an essential role in orchestrating T cell—antigen-presenting cell (APC) encounters in the draining LN following vaccination, and such interactions enhance the magnitude of the memory T cell pool (3–5). In the current study, we investigate the cellular responses in the tumor-draining lymph nodes (TDLNs) of a CCL3-secreting CT26 colon tumor (L3TU) as compared to wild-type tumor (WTTU) during the priming phase of an antitumor response (≤10 days). In comparison to WTTU, inoculation of L3TU resulted in suppressed tumor growth, a phenomenon that is accompanied by altered in vivo inflammatory responses on several fronts. Autologous tumor-derived CCL3 (aCCL3) secretion by L3TU bolstered the recruitment of T- and B-lymphocytes, tissue-migratory CD103⁺ dendritic cells (DCs), and CD49b⁺ natural killer (NK) cells, resulting in significant increases in the differentiation and activation of multiple Interferon-gamma (IFNγ)-producing leukocytes in the TDLN. During this early phase of immune priming, NK cells constitute the major producers of IFNγ in the TDLN. CCL3 also enhances CD8+ T cell proliferation and differentiation by augmenting DC capacity to drive T cell activation in the TDLN. Our results revealed that CCL3-dependent IFNγ production and CCL3-induced DC maturation drive the priming of effective antitumor immunity in the TDLN.

A reference genome for Nicotiana tabacum enables map-based cloning of homeologous loci implicated in nitrogen utilization efficiency

BACKGROUND

Tobacco (Nicotiana tabacum) is an important plant model system that has played a key role in the early development of molecular plant biology. The tobacco genome is large and its characterisation challenging because it is an allotetraploid, likely arising from hybridisation between diploid N. sylvestris and N. tomentosiformis ancestors. A draft assembly was recently published for N. tabacum, but because of the aforementioned genome complexities it was of limited utility due to a high level of fragmentation.

RESULTS

Here we report an improved tobacco genome assembly, which, aided by the application of optical mapping, achieves an N50 size of 2.17 Mb and enables anchoring of 64% of the genome to pseudomolecules; a significant increase from the previous value of 19%. We use this assembly to identify two homeologous genes that explain the differentiation of the burley tobacco market class, with potential for greater understanding of Nitrogen Utilization Efficiency and Nitrogen Use Efficiency in plants; an important trait for future sustainability of agricultural production.

CONCLUSIONS

Development of an improved genome assembly for N. tabacum enables what we believe to be the first successful map-based gene discovery for the species, and demonstrates the value of an improved assembly for future research in this model and commercially-important species.

Regulatory T cells exhibit distinct lymph node homing and trafficking kinetics as compared to conventional CD4+ T cells

Regulatory T cells (Tregs) express the canonical marker Foxp3 and are critical for suppressing the immune response in homeostatic and inflammatory conditions. Despite how widely studied CD4+Foxp3+ Tregs are in mice, their physiologic trafficking and scanning behavior of antigen-presenting cells in secondary lymphoid organs (SLOs) have yet to be quantitatively analyzed in the intravital setting. We have previously described the dynamics of T cell trafficking through SLOs and scanning of dendritic cells (DCs), revealing that CD4+ T cells and CD8+ T cells exhibit different transit kinetics through lymph nodes (LNs). On average, CD4+ T cells spend less time scanning for self-peptide/MHC (self-pMHC), dwell shorter in LNs, and egress faster compared to CD8+ T cells. Here we use flow cytometry and 2-photon laser scanning microscopy (2-PLSM) to quantitate the homeostatic trafficking behavior and surveillance strategy of Tregs in LNs and to compare their behavior to conventional T cells (Tconvs). Our data reveal significant differences in Treg versus Tconv homing and transit through peripheral and mesenteric LNs. We find that Tregs with an effector phenotype are preferentially retained in LNs, and complementary transwell assays demonstrate that Tregs have blunted response to CCL21 compared to Tconvs. Finally, we use intravital 2-PLSM to quantify the contribution of self-pMHC recognition to Treg kinetics and scanning of DCs in peripheral and mesenteric LNs, taking advantage of a novel gut SLO stabilization device allowing up to 10 hours of continuous imaging. These results add quantitative data to the emerging paradigm that self-pMHC interactions dynamically control homeostatic Treg retainment and localized suppressive function in LNs.

CCL3 augment antitumor immune priming in the tumor draining lymph node

Lymph nodes (LNs) represent an area of interest for targeting metastatic tumors because they play an essential role in tumor survival in non-native tissues. The chemokine CCL3 is important in recruiting first-responder immune cells to areas of epithelial insult and orchestrating cellular contacts in the LNs of vaccinated mice that subsequently lead toward the enhancement of memory CD8+ T cell generation. We hypothesize that by introducing a continuous supply of CCL3 into the microenvironment of a metastatic tumor, we can redirect a LN destined for tumor-tolerance toward the production of greater antitumor cellular responses. To interrogate our hypothesis, we subcutaneously inoculated naïve murine recipients with a Balb/c colon metastatic tumor (CT26) that is either the wild-type (WTTUs) or WTTUs transfected to secrete CCL3 (L3TUs). Immunocompetent mice injected with L3TUs resulted in a suppression of tumor growth compared to the WTTU. In vivo analysis across 7-days post-tumor injections with WTTUs or L3TUs, revealed an enhanced accumulation of endogenous DCs, NKs, and lymphocytes in the TDLNs. In vitro analysis showed that OVA-peptide or whole-protein-pulsed bone marrow derived dendritic cells (BMDCs) cultured with CCL3, showed an enhanced capacity to induce proliferation of antigen-specific T cells. Examination of the day-5 TDLNs for direct signs of adaptive antitumor responses also revealed an enhanced production of the antitumor cytokine, IFNγ compared to WTTUs and the specific recruitment of antitumor-associated DCs to the TDLN.

Fibroblastic niches prime T cell alloimmunity through Delta-like Notch ligands

Alloimmune T cell responses induce graft-versus-host disease (GVHD), a serious complication of allogeneic bone marrow transplantation (allo-BMT). Although Notch signaling mediated by Delta-like 1/4 (DLL1/4) Notch ligands has emerged as a major regulator of GVHD pathogenesis, little is known about the timing of essential Notch signals and the cellular source of Notch ligands after allo-BMT. Here, we have shown that critical DLL1/4-mediated Notch signals are delivered to donor T cells during a short 48-hour window after transplantation in a mouse allo-BMT model. Stromal, but not hematopoietic, cells were the essential source of Notch ligands during in vivo priming of alloreactive T cells. GVHD could be prevented by selective inactivation of Dll1 and Dll4 in subsets of fibroblastic stromal cells that were derived from chemokine Ccl19-expressing host cells, including fibroblastic reticular cells and follicular dendritic cells. However, neither T cell recruitment into secondary lymphoid organs nor initial T cell activation was affected by Dll1/4 loss. Thus, we have uncovered a pathogenic function for fibroblastic stromal cells in alloimmune reactivity that can be dissociated from their homeostatic functions. Our results reveal what we believe to be a previously unrecognized Notch-mediated immunopathogenic role for stromal cell niches in secondary lymphoid organs after allo-BMT and define a framework of early cellular and molecular interactions that regulate T cell alloimmunity.

Adoptive natural killer cell therapy is effective in reducing pulmonary metastasis of Ewing sarcoma

The survival of patients with metastatic or relapsed Ewing sarcoma (ES) remains dismal despite intensification of combination chemotherapy and radiotherapy, precipitating the need for novel alternative therapies with minimal side effects. Natural killer (NK) cells are promising additions to the field of cellular immunotherapy. Adoptive NK cell therapy has shown encouraging results in hematological malignancies. Despite these initial promising successes, however, NK cell therapy for solid tumors remains to be investigated using in vivo tumor models. The purpose of this study is to evaluate the efficacy of ex vivo expanded human NK cells in controlling primary and metastatic ES tumor growth in vitro and in vivo. Using membrane-bound IL-21 containing K562 (K562-mbIL-21) expansion platform, we were able to obtain sufficient numbers of expanded NK (eNK) cells that display favorable activation phenotypes and inflammatory cytokine secretion, along with a strong in vitro cytotoxic effect against ES. Furthermore, eNK therapy significantly decreased lung metastasis without any significant therapeutic effect in limiting primary tumor growth in an in vivo xenograft model. Our data demonstrate that eNK may be effective against pulmonary metastatic ES, but challenges remain to direct proper trafficking and augmenting the cytotoxic function of eNK to target primary tumor sites.

Abstract A119: CCL3 in the tumor microenvironment augments antitumor immune priming in the lymph node

Any therapeutic approach toward the eradication of metastatic tumor cells must involve targeting both the tumor's primary site of origin and those seeding in secondary tissues where metastasis has occurred. Lymph nodes represent an area of interest for targeting metastatic tumors because they play an essential role in tumor survival in non-native tissues. Interrogation of early cellular events in the draining lymph nodes (DLNs) during the initial priming of the adaptive T cell response can reveal new insights into how LN cells respond to a metastasizing tumor. The inflammatory chemokine CCL3 is important in orchestrating cellular contacts in vaccinated lymph nodes (LNs) and enhancing memory T cell generation. CCL3 has also been implicated in the modification and recruitment of natural killer (NK) cells and dendritic cells (DCs) to sites of epithelial insult and are important in establishing whether tumors will be tolerated or rejected. We hypothesize that by introducing a continuous supply of CCL3 into the microenvironment of a metastatic tumor, we can redirect a lymph node destined for tumor-tolerance toward the production of greater antitumor cellular responses. To interrogate our hypothesis, we subcutaneously inoculated naïve murine recipients with a Balb/c colon metastatic tumor (CT26) that is either the wild-type (WTTUs) or WTTUs transfected to secrete CCL3 (L3TUs). Immunocompetent mice injected with L3TUs resulted in a suppression of tumor growth compared to the WTTU group in a CD8+ T cell dependent manner. 1, 3, and 5-days after injection with WTTUs or L3TUs, there was an enhanced accumulation of endogenous DCs, NKs, and T cells in the DLNs and non-draining LNs (NDLNs). In vivo analysis of DCs in the DLN of L3TUs showed increased numbers of CD11c+ cells that upregulated the T cell costimulatory molecule, CD86+, while in vitro, SIINFEKL-pulsed BMDCs cultured with CCL3, showed an enhance capacity to induce proliferation of OT-I (CD8+) T cells. Examination of the day-5 DLN for direct signs of adaptive antitumor responses revealed an enhanced production of the antitumor cytokine, IFNγ, in the L3TU group, while the WTTU group showed a greater accumulation of CD4+ T-regulatory cells (Treg) over convention CD4+ T cells. Together these data suggest that CCL3 may enhance the overall immune response in the DLN in three ways. First, CCL3 attracts key cell-types such as NK cells to the DLN in larger quantities that can directly interact with DCs or T cells to enhance the development of IFNγ producing immune cells. Second, CCL3 directly influences DC maturation and indirectly enhances T cell proliferation. Third, CCL3 directly enhances the overall systemic accumulation of lymphocyte and myeloid cells in the DLN and NDLNs.

Citation Format: Frederick Allen, Joseph M. Nthale, Saada K. Eid, Peter Rauhe, David Askew, Jay Myers, Alexander Tong, Alex Y. Huang. CCL3 in the tumor microenvironment augments antitumor immune priming in the lymph node [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr A119.

Abstract LB-151: Positively selected enhancer elements endow tumor cells with metastatic competence

Metastasis results from a complex set of traits acquired by tumor cells, distinct from those necessary for tumorigenesis. Here, we investigate the contribution of enhancer elements to the metastatic phenotype of osteosarcoma. Through epigenomic profiling, we identify substantial differences in signature enhancer-histone marks between near-isogenic pairs of high and low lung-metastatic osteosarcoma cells. We term these regions Metastatic Variant Enhancer Loci (Met-VELs). Met-VELs drive coordinated waves of gene expression during metastatic colonization of the lung. Met-VELs cluster non-randomly, indicating that activity of these enhancers and their associated gene targets is positively selected. Osteosarcoma lung metastasis is inhibited by global interruptions of Met-VEL associated gene expression via pharmacologic BET inhibition, by knockdown of AP-1 transcription factors whose motifs are enriched in Met-VELs, and by knockdown of individual genes activated by Met-VELs. These observations have implications for the discovery and development of targeted anti-metastatic therapies.

Citation Format: James J. Morrow, Tyler E. Miller, Alina Saiakhova, Michael M. Lizardo, Cynthia F. Bartels, Ian Bayles, Stevephen Hung, Arnulfo Mendoza, Jay T. Myers, Frederick Allen, Analisa DiFeo, Brian P. Rubin, Alex Y. Huang, Paul S. Meltzer, Lee J. Helman, Chand Khanna, Peter C. Scacheri. Positively selected enhancer elements endow tumor cells with metastatic competence. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-151.

Unique Transcompartmental Bridge: Antigen-Presenting Cells Sampling across Endothelial and Mucosal Barriers

Potentially harmful pathogens can gain access to tissues and organ systems through body sites that are in direct contact with the outside environment, such as the skin, the gut, and the airway mucosa. Antigen-presenting cells (APCs) represent a bridge between the innate and adaptive immunity, and their capacity for constant immune surveillance and rapid sampling of incoming pathogens and other potentially harmful antigens is central for mounting an effective and robust protective host response. The classical view is that APCs perform this task efficiently within the tissue to sense invading agents intra-compartmentally. However, recent data based on high resolution imaging support an additional transcompartmental surveillance behavior by APC by reaching across intact physical barriers. In this review, we summarize intravital microscopic evidences of APC to sample antigens transcompartmentally at the gut mucosa and other body sites.

Quantification of lymph node transit times reveals differences in the trafficking behavior of regulatory versus conventional CD4+ T cells

Regulatory T cells (Tregs) express the canonical marker Foxp3 and are critical for suppressing the immune response in homeostatic and inflammatory conditions. Despite how widely studied CD4+Foxp3+ Tregs are in mice, their physiologic trafficking and scanning behavior of antigen-presenting cells in secondary lymphoid organs (SLOs) have yet to be quantitatively analyzed in the intravital setting. Our laboratory has previously described the dynamics of T cell trafficking through SLOs and scanning of dendritic cells (DCs), revealing that CD4+ T cells and CD8+ T cells exhibit different transit kinetics through lymph nodes (LNs). On average, CD4+ T cells spend less time scanning for self-peptide/MHC (self-pMHC), dwell shorter in LNs, and egress faster compared to CD8+ T cells. Here we use flow cytometry and 2-photon laser scanning microscopy (2-PLSM) to quantitate the homeostatic trafficking behavior and surveillance strategy of Tregs in LNs and to compare their behavior to conventional T cells (Tconvs). Our data reveal surprising differences in Treg versus Tconv trafficking in mesenteric versus other peripheral LNs. Furthermore, we find that Treg LN transit time is heavily dependent on recognition of self-pMHC. Finally, we use intravital 2-PLSM to quantify the contribution of self-pMHC recognition to Treg kinetics and scanning of DCs in peripheral and mesenteric LNs. These results add quantitative data to the emerging paradigm that self-pMHC interactions dynamically control homeostatic Treg retainment and localized suppressive function in peripheral LNs.

CCL3 in the tumor microenvironment augments the antitumor immune response

CCL3 is important in orchestrating cellular contacts in vaccinated lymph nodes (LNs) and enhancing memory T cell generation. Furthermore, dendritic cells (DCs) have been shown to mediate both tumor-tolerance and antitumor immunity in some tumor models. We hypothesize that incorporating CCL3 into tumor vaccines can enhance antitumor immunity. We injected into the footpad of naïve recipients, wild-type tumors (WTTUs) or CCL3-secreting (L3TUs) colon tumors (CT26). Immunocompetent mice injected with L3TUs resulted in a suppression of tumor growth compared to the WTTU group in a CD8+ T cell dependent manner. 1- and 5- days after injection with WTTUs or L3TUs, there was a superior accumulation of endogenous DCs and activated T cells in the draining lymph node (DLN) of the L3TU group. Concurrently bone marrow dendritic cells (BMDC)-tumor or -T cell co-culturing experiments were conducted to assess the effects the tumor and its microenvironment (+/− CCL3) has on DC function. In vitro experiments using BMDCs cultured with CCL3 enhanced their expression of MHC-I, CD86, and CCR7. BMDCs cultured with CCL3, then pulsed with SIINFEKL peptide, also showed an enhance capacity to proliferate OT-I (CD8+) T cells. In vivo analysis reveal that BMDCs injected directly into mice bearing L3TUs showed an enhanced ability to home to DLNs. Moreover, ElISpot and intracellular analysis of isolated T cells from LNs revealed an enhanced ability for T cells to upregulate IFNγ post-tumor injection with L3TUs. Together these data reveal that CCL3 in the tumor microenvironment leads to a reduction in tumor growth and improved T cell responses in the DLN, which may be a result of an enhanced capacity for DCs to home to the DLN and activate antitumor T cells.

Polyphenol administration impairs T-cell proliferation by imprinting a distinct dendritic cell maturational profile

Currently little is known as to how nutritionally derived compounds may affect dendritic cell (DC) maturation and potentially prevent inappropriate inflammatory responses that are characteristic of chronic inflammatory syndromes. Previous observations have demonstrated that two polyphenols quercetin and piperine delivered through reconstituted oil bodies (ROBs-QP) can influence DC maturation in response to LPS leading to a modulated inflammatory response. In the present study, we examined the molecular effects of ROBs-QP exposure on DC differentiation in mice and identified a unique molecular signature in response to LPS administration that potentially modulates DC maturation and activity in inflammatory conditions. Following LPS administration, ROBs-QP-exposed DCs expressed an altered molecular profile as compared with control DCs, including cytokine and chemokine production, chemokine receptor repertoire, and antigen presentation ability. In vivo ROBs-QP administration suppresses antigen-specific T-cell division in the draining lymph nodes resulting from a reduced ability to create stable immunological synapse. Our data demonstrate that polyphenols exposure can drive DCs toward a new anti-inflammatory molecular profile capable of dampening the inflammatory response, highlighting their potential as complementary nutritional approaches in the treatment of chronic inflammatory syndromes.

Inflammatory chemokine CCL3 Leads to enhanced antitumor development in the draining lymph node (TUM10P.1053)

CCL3 has been shown to be important in orchestrating cellular contacts in vaccinated lymph nodes. Moreover, dendritic cells can mediate both tumor tolerance and anti-tumor immunity in some tumor models. We hypothesize that incorporating CCL3 into tumor vaccines can enhance anti-tumor immunity. We inoculated naïve recipient mice with either WT or CCL3-secreting colon tumors. CCL3-secreting tumors showed enhanced antitumor immunity and suppressed growth kinetics in immunocompetent mice versus WT-tumors. Relative to non-injected controls or WT-injected tumors, 3 days after injections CCL3-secreting tumors revealed an increase of CD4+, CD8+, and CD19+ lymphocyte in the draining lymph node. Concurrently we conducted in vitro BMDCs experiments to assess the effects the tumor microenvironment (+/- CCL3) has on the capacity of DCs to upregulate T cell activation and adhesion molecules. BMDCs differentiated in the presence of CCL3 showed a greater capacity to upregulation CD86, ICAM1, CD11b, and CCR7 before and after LPS stimulation. Moreover, BMDCs cultured in the presence of WT and CCL3-secreting tumor supernatants revealed an increase in CD86, MHCII, and CCR7 before and after LPS stimulation. Together these data reveal that CCL3 in the tumor microenvironments leads to a reduction in tumor growth and early lymphocyte accumulation in the DLN, which may be a result of an enhanced capacity for DCs to home to the DLN and activate antitumor T cells.

Homeostatic regulatory T cell trafficking in peripheral lymph nodes (LYM2P.731)

Regulatory T cells (Tregs) express the canonical marker Foxp3 and are critical for suppressing the immune response in homeostatic and inflammatory conditions. As widely studied as CD4+Foxp3+ Tregs are in mice, their physiologic trafficking and scanning behavior of antigen-presenting cells in secondary lymphoid organs (SLOs) have yet to be quantitatively analyzed. Our laboratory has previously described the dynamics of naïve T cell trafficking through SLOs and scanning of dendritic cells, revealing that CD4+ T cells and CD8+ T cells have distinct dynamic behaviors in the lymph node (LN). On average, CD4+ T cells spend less time scanning for self-peptide/MHC (self-pMHC), dwell shorter in LNs, and egress faster compared to CD8+ T cells. In this study, we use flow cytometry and 2-photon laser scanning microscopy to quantitate the trafficking kinetics and surveillance strategy of naïve Tregs in C57BL/6 mice LNs and to compare their behavior to conventional T cells. Our data reveal differences in naïve Treg trafficking in mesenteric versus other peripheral LNs. We also show that self-pMHC recognition regulates the scanning behavior and localization of Tregs in peripheral LNs. In addition, we describe a novel imaging platform for high-resolution intravital microscopy of T cell behavior within mesenteric LNs. These results add to mounting evidence that self-pMHC interactions dynamically control physiologic Treg retainment and contact-dependent suppressive function in peripheral LNs.

Murine leukemia virus envelope gp70 is a shared biomarker for the high-sensitivity quantification of murine tumor burden

The preclinical development of anticancer drugs including immunotherapeutics and targeted agents relies on the ability to detect minimal residual tumor burden as a measure of therapeutic efficacy. Real-time quantitative (qPCR) represents an exquisitely sensitive method to perform such an assessment. However, qPCR-based applications are limited by the availability of a genetic defect associated with each tumor model under investigation. Here, we describe an off-the-shelf qPCR-based approach to detect a broad array of commonly used preclinical murine tumor models. In particular, we report that the mRNA coding for the envelope glycoprotein 70 (gp70) encoded by the endogenous murine leukemia virus (MuLV) is universally expressed in 22 murine cancer cell lines of disparate histological origin but is silent in 20 out of 22 normal mouse tissues. Further, we detected the presence of as few as 100 tumor cells in whole lung extracts using qPCR specific for gp70, supporting the notion that this detection approach has a higher sensitivity as compared with traditional tissue histology methods. Although gp70 is expressed in a wide variety of tumor cell lines, it was absent in inflamed tissues, non-transformed cell lines, or pre-cancerous lesions. Having a high-sensitivity biomarker for the detection of a wide range of murine tumor cells that does not require additional genetic manipulations or the knowledge of specific genetic alterations present in a given neoplasm represents a unique experimental tool for investigating metastasis, assessing antitumor therapeutic interventions, and further determining tumor recurrence or minimal residual disease.

Inflammatory chemokine CCL3 suppresses preferential tumor-associated accumulation of B cells and CD4 T cells in tumor-draining lymph nodes (P2017)

We have previously demonstrated that CCL3 (MIP-1α) and CCL4 (MIP-1β) were important in orchestrating cellular contacts in vaccinated lymph nodes (LNs) and can enhance memory T cell generation (Castellino et al). We hypothesize that incorporating CCL3 and CCL4 into tumor vaccines can enhance anti-tumor immunity. Using colon tumor model CT26, we generated tumors that secret CCL3, CCL4 or both, and inoculate them live into the footpad of naïve recipients. CCL3-secreting tumors failed to grow in immunocompetent mice, and enhance antitumor immunity when used as a vaccine. Flow cytometric analysis of draining popliteal LNs 3 days after live cell injection revealed that while the total LN cell number increased by 2.03 fold after wild type (WT) tumor challenge relative to contralateral LN (conLN), CCL3-secreting tumor injection failed to do so despite the presence of tumor cells in the LNs. CD4 cells in the WT draining LN were 1.58 fold higher compared to conLN, but remained unchanged in CCL3-secreting tumors. Striking differences were seen in B cells where WT tumor resulted in a 7.04-fold increased, but CCL3-secreting tumors only caused a modest 2.04-fold change. Dynamic intravital 2-photon microscopy and tissue histology studies further revealed that tumors occupy the B cell follicle during early metastasis, and exogenous CCL3 gradient may potentially alter lymphocyte homeostasis in tumor draining LN, resulting in immune activation rather than tolerance against CT26.

Bilateral thoracic sympathetic block for refractory polymorphic tachycardia

INTRODUCTION

Extensive evidence has established a link between sympathetic nervous system hyperactivity, ventricular arrhythmias, and sudden cardiac death. For this reason, cardiac sympathectomy is often beneficial in the treatment of patients at high risk for ventricular ectopy, although it involves an invasive procedure associated with potential morbidity. We report a case in which we used guided lytic thoracic sympathetic block in a patient with underlying cardiomyopathy and refractory polymorphic ventricular tachycardia.

CLINICAL FEATURES

A 74-yr-old African American male with ischemic cardiomyopathy presented with refractory episodes of ventricular tachycardia despite maximal medical therapy involving antiarrhythmic drugs and previous interventions, including endovascular epicardial ablation and open cryoablation via sternotomy. During his inpatient admission, the patient developed sustained ventricular tachycardia associated with cardiac depression requiring vasopressors. An open thoracoscopic sympathectomy was considered as a possible treatment, but in our view, the patient would not tolerate this procedure. As an alternative, the pain medicine team successfully performed a lytic thoracic sympathetic block. Subsequently, the patient demonstrated a period of clinical improvement with no apparent morbidity related to the procedure.

CONCLUSION

Lytic thoracic sympathetic blockade is a novel technique for the treatment of sympathetically mediated ventricular tachycardia, and it is less invasive than other types of cardiac sympathectomy. Additional studies are required to evaluate this treatment as a viable alternative in patients at high risk for ventricular ectopy. This report suggests the feasibility of this approach and the potential for minimal morbidity in cases of refractory ventricular arrhythmias.

Regional brain blood flow in mouse: quantitative measurement using a single-pass radio-tracer method and a mathematical algorithm

We have developed a reliable experimental method for measuring local regional cerebral blood flows in anesthetized mice. This method is an extension of the well-established single-pass dual-label indicator method for simultaneously measuring blood flow and glucose influx in rat brains. C57BL6J mice (n = 10) were anesthetized and regional blood flows (ml/min/g) were measured using the radio-tracer method. To test the sensitivity of this method we used a mathematical algorithm to predict the blood flows and compared the two sets of results.Measured regional blood flows between 0.7 and 1.7 ml/min/g were similar to those we have previously reported in the rat. The predicted blood flows using an assumed linearly increasing arterial tracer concentration-versus-time profile (that is, a ramp) were similar to the values measured in the physiological experiments (R(2) 0.99; slope 0.91). Thus,measurements of local regional cerebral blood flow in anesthetized mice using a single-pass radio-tracer method appear to be reliable.

The impact of hypodontia: a qualitative study on the experiences of patients

Congenital absence of teeth affects 2-6 per cent of the population, but its impact on quality of life (QoL) is not fully understood. The symptoms of hypodontia can vary and therefore also the treatment and management of this condition. Determining and understanding the possible impact of hypodontia on patients could inform and improve the management of such patients. A purposive sample of 10 participants aged 16-25 years (five males and five females) with mild, moderate, or severe hypodontia at various stages of treatment was recruited. The participants had previously completed a 49-item Oral Health Impact Profile (OHIP) questionnaire with summary scores ranging from 24 to 143. All subjects participated in semi-structured interviews, and these were transcribed and analysed using NVivo software. The results show that the role of hypodontia patients in the treatment decision-making process changes significantly as they move from childhood to adulthood. Participants indicated dissatisfaction with the lack of communication with dental services throughout early adolescence as they became more cognizant of their condition which in turn led to concerns with regard to appearance which impacted on their psychosocial well-being. Hypodontia patients expect improved communication with dental practitioners and services as they become more cognizant of their condition and wish to become more actively involved in the decision-making process regarding their current and future treatment.

Case report: intracranial placement of a nasotracheal tube in a patient with Goldenhar syndrome associated with cribriform plate agenesis

We describe a case of inadvertent intracranial placement of a nasotracheal tube in a patient with an undiagnosed major congenital cranial anomaly (a variant of Goldenhar syndrome, which included absence of the cribriform plate). We believe that this is the first reported case in which this complication arose as a result of a congenital abnormality rather than traumatic or iatrogenic disruption of the skull base. We conclude that patients with known craniofacial abnormalities or associated syndromes scheduled for procedures involving planned nasotracheal intubation or nasogastric tube placement should undergo preoperative cranial imaging studies to verify an intact skull base.

Angiostrongylus vasorum infection in dogs: Presentation and risk factors

Infection with the nematode Angiostrongylus vasorum is an emerging cause of canine disease in Europe and part of North America, yet published data on its epidemiology in endemic areas are lacking. This study tested faecal samples from 897 dogs attending veterinary practices in the southern part of Great Britain, a long standing endemic focus. Among 790 dogs presenting with respiratory or other signs broadly suggestive of angiostrongylosis, 16% tested positive on a single Baermann's examination, compared with 2% of healthy dogs in the same catchment areas. Risk factors for positive tests included age (higher risk in younger dogs), season (more cases earlier in the calendar year), and worming history (lower risk if given milbemycin oxime in the past 12 weeks). Sex, neutering status and breed were not significant in terms of risk of testing positive. The most common clinical signs in infected dogs were respiratory, along with non-specific signs such as lethargy and exercise intolerance, while bleeding, neurological and gastrointestinal signs were also recorded. Around half the dogs sampled that showed signs of extra-pulmonary disease also had respiratory signs. Direct faecal smears and Baermann's tests read after one hour detected 56% and 83% of diagnosed cases respectively. The data confirm that A. vasorum is commonly associated with disease in endemic areas, which manifests with a broad range of signs at primary care level. Information on risk factors is useful in diagnosis and control, and forms a basis for further epidemiological investigation.

Parenteral and enteral metabolism of anaplerotic triheptanoin in normal rats. II. Effects on lipolysis, glucose production, and liver acyl-CoA profile

The anaplerotic odd-medium-chain triglyceride triheptanoin is used in clinical trials for the chronic dietary treatment of patients with long-chain fatty acid oxidation disorders. We previously showed (Kinman RP, Kasumov T, Jobbins KA, Thomas KR, Adams JE, Brunengraber LN, Kutz G, Brewer WU, Roe CR, Brunengraber H. Am J Physiol Endocrinol Metab 291: E860-E866, 2006) that the intravenous infusion of triheptanoin increases lipolysis traced by the turnover of glycerol. In this study, we tested whether lipolysis induced by triheptanoin infusion is accompanied by the potentially harmful release of long-chain fatty acids. Rats were infused with heptanoate +/- glycerol or triheptanoin. Intravenous infusion of triheptanoin at 40% of caloric requirement markedly increased glycerol endogenous R(a) but not oleate endogenous R(a). Thus, the activation of lipolysis was balanced by fatty acid reesterification in the same cells. The liver acyl-CoA profile showed the accumulation of intermediates of heptanoate beta-oxidation and C(5)-ketogenesis and a decrease in free CoA but no evidence of metabolic perturbation of liver metabolism such as propionyl overload. Our data suggest that triheptanoin, administered either intravenously or intraduodenally, could be used for intensive care and nutritional support of metabolically decompensated long-chain fatty acid oxidation disorders.

Female receptivity phenotype of icebox mutants caused by a mutation in the L1-type cell adhesion molecule neuroglian

Relatively little is known about the genes and brain structures that enable virgin female Drosophila to make the decision to mate or not. Classical genetic approaches have identified several mutant females that have a reluctance-to-mate phenotype, but most of these have additional behavioral defects. However, the icebox (ibx) mutation was previously reported to lower the sexual receptivity of females, without apparently affecting any other aspect of female behavior. We have shown that the ibx mutation maps to the 7F region of the Drosophila X chromosome to form a complex complementation group with both lethal and viable alleles of neuroglian (nrg). The L1-type cell adhesion molecule encoded by nrg consists of six immunoglobulin-like domains, five fibronectin-like domains, one transmembrane domain and one alternatively spliced intracellular domain. The ibx strain has a missense mutation causing a glycine-to-arginine change at amino acid 92 in the first immunoglobulin domain of nrg. Defects in the central brain of ibx mutants are similar to those observed in another nrg mutant, central brain deranged(1) (ceb(1)). However, both ceb(1) homozygous and ceb(1)/ibx heterozygous females are receptive. The expression of a transgene containing the non-neural isoform of nrg rescues both the receptivity and the brain structure phenotypes of ibx females.

Characteristics of a monoclonal antibody to the thyrotropin receptor that acts as a powerful thyroid-stimulating autoantibody antagonist

Analysis of nine mouse monoclonal antibodies (mAbs) to the thyrotropin receptor (TSHR) with TSH antagonist activity showed that only one of the mAbs (RSR B2) was an effective antagonist of the human thyroid stimulating autoantibody M22. Crystals of B2 Fab were analyzed by x-ray diffraction and a crystal structure at 3.3 A resolution was obtained. The surface charge and topography of the B2 antigen binding site were markedly different from those of the thyroid-stimulating mAb M22 and these differences might contribute to the different properties of the two mAbs. B2 (but not other mouse TSHR-specific mAbs) was also an effective antagonist of thyroid stimulating autoantibody activity in 14 of 14 different sera from patients with Graves' disease. 125I-labeled B2 bound to the TSHR with high affinity (2 x 10(10) L/mol) and patient serum TSHR autoantibodies inhibited labeled B2 binding to the receptor in a similar way to inhibition of labeled TSH binding (r = 0.75; n = 20). Furthermore, labeled B2 binding was inhibited by patient serum TSHR autoantibodies with TSH antagonist activity and also by mouse and human thyroid stimulating mAbs. Overall, mAb B2 is a powerful antagonist of thyroid stimulating autoantibodies (and TSH) thus resembling closely patient serum TSH antagonist TSHR autoantibodies. Furthermore, B2 might have potentially important in vivo applications when tissues containing the TSHR (including those in the orbit) need to be made unresponsive to stimulating autoantibodies.

Impact of mandatory resident work hour limitations on medical students' interest in surgery

BACKGROUND

The number of US medical students applying for general surgery residency has been declining. Recent studies have shown that the issue of "controllable lifestyle" has become a critical factor in medical students' decision-making process. We postulate that widespread implementation of resident work hour limitations would bolster medical students' interest in pursuing surgical careers.

STUDY DESIGN

Students from New York University School of Medicine were surveyed about their attitudes toward work hour limitations and its effect on their interest in pursuing a surgical residency. One hundred thirty-two students participated.

RESULTS

Nearly 95% of respondents believed that work hour limitations were a positive change and, if all other factors were equal, they would choose a training program that used work hour limitations over one that did not. The most common reasons cited in favor of limits were improvements in resident lifestyle (42%) and patient safety (34%). Fifty-three percent of respondents indicated that presence of work hour limitations alone would increase their interest in considering a surgical residency and only 2% of medical students indicated that it would lessen their interest in surgery. Not surprisingly, intellectual interest in a specialty was the most important factor in choosing a residency for 86% of students. Nevertheless, work hour limitations were designated a higher priority than future salary by 55% of medical students.

CONCLUSIONS

The presence of work hour limitations has a positive impact on medical students' interest in surgery. Widespread implementation of work hour limitations may bolster the number of applications for surgical residency.

Attitudes of applicants for surgical residency toward work hour limitations

BACKGROUND

There is an ongoing debate regarding the merits of resident work-hour limitations. We postulated that this issue would be a factor in the decision-making process of applicants to surgical residency.

METHODS

Candidates for surgical residency at a university-based program completed an anonymous survey during their visit. Data was analyzed by analysis of variance and the chi-square test.

RESULTS

Most candidates viewed work-hour limitations as being favorable to their future training. Nevertheless, work-hour limitations ultimately were not a critical factor in the decision-making process compared with issues such as quality of training and program reputation. Candidates ranked "reading in surgery" the most likely way they would spend the leisure time afforded by work-hour limitations.

CONCLUSIONS

Most applicants for surgical residency consider work hour-limitations as being favorable to their training and view the extra free time as an opportunity for furthering their education. However, other issues take precedence when choosing a residency.

A comparison of lorazepam, diazepam, and placebo for the treatment of out-of-hospital status epilepticus

BACKGROUND

It is uncertain whether the administration of benzodiazepines by paramedics is an effective and safe treatment for out-of-hospital status epilepticus.

METHODS

We conducted a randomized, double-blind trial to evaluate intravenous benzodiazepines administered by paramedics for the treatment of out-of-hospital status epilepticus. Adults with prolonged (lasting five minutes or more) or repetitive generalized convulsive seizures received intravenous diazepam (5 mg), lorazepam (2 mg), or placebo. An identical second injection was given if needed.

RESULTS

Of the 205 patients enrolled, 66 received lorazepam, 68 received diazepam, and 71 received placebo. Status epilepticus had been terminated on arrival at the emergency department in more patients treated with lorazepam (59.1 percent) or diazepam (42.6 percent) than patients given placebo (21.1 percent) (P=0.001). After adjustment for covariates, the odds ratio for termination of status epilepticus by the time of arrival in the lorazepam group as compared with the placebo group was 4.8 (95 percent confidence interval, 1.9 to 13.0). The odds ratio was 1.9 (95 percent confidence interval, 0.8 to 4.4) in the lorazepam group as compared with the diazepam group and 2.3 (95 percent confidence interval, 1.0 to 5.9) in the diazepam group as compared with the placebo group. The rates of respiratory or circulatory complications (indicated by bag valve-mask ventilation or an attempt at intubation, hypotension, or cardiac dysrhythmia) after the study treatment was administered were 10.6 percent for the lorazepam group, 10.3 percent for the diazepam group, and 22.5 percent for the placebo group (P=0.08).

CONCLUSIONS

Benzodiazepines are safe and effective when administered by paramedics for out-of-hospital status epilepticus in adults. Lorazepam is likely to be a better therapy than diazepam.

The prehospital treatment of status epilepticus (PHTSE) study: design and methodology

Status epilepticus is a neurological emergency that is typically first encountered and managed in the prehospital environment. Although aggressive pharmacological treatment of status epilepticus is well established in the emergency department and hospital settings, the relative risks and benefits of active therapy for status epilepticus in the prehospital setting are not known. The Prehospital Treatment of Status Epilepticus (PHTSE) study is a prospective, randomized, double-blind, placebo-controlled study designed to address the following aims: (1) to determine whether administration of benzodiazepines by paramedics is an effective and safe means of treating status epilepticus in the prehospital setting and whether this therapy influences longer-term patient outcome, (2) to determine whether lorazepam is superior to diazepam for the treatment of status epilepticus in the prehospital setting, and (3) to determine whether control of status epilepticus prior to arrival to the emergency department influences patient disposition. The initial phase of the PHTSE study began in January 1994 and was completed in February 1999 after the successful enrollment of 205 patients into the three treatment arms. In this paper, we describe the rationale for the conceptualization of the study and details of the study design and methodology, and emphasize some aspects of study implementation that are unique to research involving the emergency medical system.