The fast multi-frame X-ray diffraction detector at the Dynamic Compression Sector

A multi-frame, X-ray diffraction (XRD) detector system has been developed for use in time-resolved XRD measurements during single-event experiments at the Dynamic Compression Sector (DCS) at the Advanced Photon Source (APS). The system is capable of collecting four sequential XRD patterns separated by 153 ns, the period of the APS storage ring in the 24-bunch mode. This capability allows an examination of the temporal evolution of material dynamics in single-event experiments, such as plate impact experiments, explosive detonations, and split-Hopkinson pressure bar experiments. This system is available for all user experiments at the DCS. Here, the system description and measured performance parameters (detective quantum efficiency, spatial and temporal resolution, and dynamic range) are presented along with procedures for synchronization and image post-processing.

Genetic and pharmacologic modulation of cementogenesis via pyrophosphate regulators

Pyrophosphate (PP_i) serves as a potent and physiologically important regulator of mineralization, with systemic and local concentrations determined by several key regulators, including: tissue-nonspecific alkaline phosphatase (ALPL gene; TNAP protein), the progressive ankylosis protein (ANKH; ANK), and ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1; ENPP1). Results to date have indicated important roles for PP_i in cementum formation, and we addressed several gaps in knowledge by employing genetically edited mouse models where PP_i metabolism was disrupted and pharmacologically modulating PP_i in a PP_i-deficient mouse model. We demonstrate that acellular cementum growth is inversely proportional to PP_i levels, with reduced cementum in Alpl KO (increased PP_i levels) mice and excess cementum in Ank KO mice (decreased PP_i levels). Moreover, simultaneous ablation of Alpl and Ank results in reestablishment of functional cementum in dKO mice. Additional reduction of PP_i by dual deletion of Ank and Enpp1 does not further increase cementogenesis, and PDL space is maintained in part through bone modeling/remodeling by osteoclasts. Our results provide insights into cementum formation and expand our knowledge of how PP_i regulates cementum. We also demonstrate for the first time that pharmacologic manipulation of PP_i through an ENPP1-Fc fusion protein can regulate cementum growth, supporting therapeutic interventions targeting PP_i metabolism.

A Simple and Scalable Strategy for Analysis of Endogenous Protein Dynamics

The ability to analyze protein function in a native context is central to understanding cellular physiology. This study explores whether tagging endogenous proteins with a reporter is a scalable strategy for generating cell models that accurately quantitate protein dynamics. Specifically, it investigates whether CRISPR-mediated integration of the HiBiT luminescent peptide tag can easily be accomplished on a large-scale and whether integrated reporter faithfully represents target biology. For this purpose, a large set of proteins representing diverse structures and functions, some of which are known or potential drug targets, were targeted for tagging with HiBiT in multiple cell lines. Successful insertion was detected for 86% of the targets, as determined by luminescence-based plate assays, blotting, and imaging. In order to determine whether endogenously tagged proteins yield more representative models, cells expressing HiBiT protein fusions either from endogenous loci or plasmids were directly compared in functional assays. In the tested cases, only the edited lines were capable of accurately reproducing the anticipated biology. This study provides evidence that cell lines expressing HiBiT fusions from endogenous loci can be rapidly generated for many different proteins and that these cellular models provide insight into protein function that may be unobtainable using overexpression-based approaches.

Paradoxical aortic stiffening and subsequent cardiac dysfunction in Hutchinson-Gilford progeria syndrome

Hutchinson-Gilford progeria syndrome (HGPS) is an ultra-rare disorder with devastating sequelae resulting in early death, presently thought to stem primarily from cardiovascular events. We analyse novel longitudinal cardiovascular data from a mouse model of HGPS (Lmna^G609G/G609G) using allometric scaling, biomechanical phenotyping, and advanced computational modelling and show that late-stage diastolic dysfunction, with preserved systolic function, emerges with an increase in the pulse wave velocity and an associated loss of aortic function, independent of sex. Specifically, there is a dramatic late-stage loss of smooth muscle function and cells and an excessive accumulation of proteoglycans along the aorta, which result in a loss of biomechanical function (contractility and elastic energy storage) and a marked structural stiffening despite a distinctly low intrinsic material stiffness that is consistent with the lack of functional lamin A. Importantly, the vascular function appears to arise normally from the low-stress environment of development, only to succumb progressively to pressure-related effects of the lamin A mutation and become extreme in the peri-morbid period. Because the dramatic life-threatening aortic phenotype manifests during the last third of life there may be a therapeutic window in maturity that could alleviate concerns with therapies administered during early periods of arterial development.

The luminescent HiBiT peptide enables selective quantitation of G protein-coupled receptor ligand engagement and internalization in living cells

G protein-coupled receptors (GPCRs) are prominent targets to new therapeutics for a range of diseases. Comprehensive assessments of their cellular interactions with bioactive compounds, particularly in a kinetic format, are imperative to the development of drugs with improved efficacy. Hence, we developed complementary cellular assays that enable equilibrium and real-time analyses of GPCR ligand engagement and consequent activation, measured as receptor internalization. These assays utilize GPCRs genetically fused to an N-terminal HiBiT peptide (1.3 kDa), which produces bright luminescence upon high-affinity complementation with LgBiT, an 18-kDa subunit derived from NanoLuc. The cell impermeability of LgBiT limits signal detection to the cell surface and enables measurements of ligand-induced internalization through changes in cell-surface receptor density. In addition, bioluminescent resonance energy transfer is used to quantify dynamic interactions between ligands and their cognate HiBiT-tagged GPCRs through competitive binding with fluorescent tracers. The sensitivity and dynamic range of these assays benefit from the specificity of bioluminescent resonance energy transfer and the high signal intensity of HiBiT/LgBiT without background luminescence from receptors present in intracellular compartments. These features allow analyses of challenging interactions having low selectivity or affinity and enable studies using endogenously tagged receptors. Using the β-adrenergic receptor family as a model, we demonstrate the versatility of these assays by utilizing the same HiBiT construct in analyses of multiple aspects of GPCR pharmacology. We anticipate that this combination of target engagement and proximal functional readout will prove useful to the study of other GPCR families and the development of new therapeutics.

Complex Formation between VEGFR2 and the β2-Adrenoceptor

Vascular endothelial growth factor (VEGF) is an important mediator of endothelial cell proliferation and angiogenesis via its receptor VEGFR2. A common tumor associated with elevated VEGFR2 signaling is infantile hemangioma that is caused by a rapid proliferation of vascular endothelial cells. The current first-line treatment for infantile hemangioma is the β-adrenoceptor antagonist, propranolol, although its mechanism of action is not understood. Here we have used bioluminescence resonance energy transfer and VEGFR2 genetically tagged with NanoLuc luciferase to demonstrate that oligomeric complexes involving VEGFR2 and the β₂-adrenoceptor can be generated in both cell membranes and intracellular endosomes. These complexes are induced by agonist treatment and retain their ability to couple to intracellular signaling proteins. Furthermore, coupling of β₂-adrenoceptor to β-arrestin2 is prolonged by VEGFR2 activation. These data suggest that protein-protein interactions between VEGFR2, the β₂-adrenoceptor, and β-arrestin2 may provide insight into their roles in health and disease.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Real-Time Ligand Binding of Fluorescent VEGF-A Isoforms that Discriminate between VEGFR2 and NRP1 in Living Cells

Fluorescent VEGF-A isoforms have been evaluated for their ability to discriminate between VEGFR2 and NRP1 in real-time ligand binding studies in live cells using BRET. To enable this, we synthesized single-site (N-terminal cysteine) labeled versions of VEGF₁₆₅a, VEGF₁₆₅b, and VEGF₁₂₁a. These were used in combination with N-terminal NanoLuc-tagged VEGFR2 or NRP1 to evaluate the selectivity of VEGF isoforms for these two membrane proteins. All fluorescent VEGF-A isoforms displayed high affinity for VEGFR2. Only VEGF₁₆₅a-TMR bound to NanoLuc-NRP1 with a similar high affinity (4.4 nM). Competition NRP1 binding experiments yielded a rank order of potency of VEGF₁₆₅a > VEGF₁₈₉a > VEGF₁₄₅a. VEGF₁₆₅b, VEGF-Ax, VEGF₁₂₁a, and VEGF₁₁₁a were unable to bind to NRP1. There were marked differences in the kinetic binding profiles of VEGF₁₆₅a-TMR for NRP1 and VEGFR2. These data emphasize the importance of the kinetic aspects of ligand binding to VEGFR2 and its co-receptors in the dynamics of VEGF signaling.

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VEGF₁₆₅a, VEGF₁₂₁a, and VEGF₁₆₅b were single-site labeled with tetramethylrhodamine

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NanoBRET quantified that VEGF-A isoforms have similar binding properties at VEGFR2

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NRP1 expressed in live cells does not bind VEGF₁₆₅b, VEGF₁₂₁a, VEGF-Ax, or VEGF₁₁₁a

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VEGFR2 and NRP1 have markedly distinct kinetic profiles binding VEGF₁₆₅a-TMR

CRISPR-Mediated Tagging of Endogenous Proteins with a Luminescent Peptide

Intracellular signaling pathways are mediated by changes in protein abundance and post-translational modifications. A common approach for investigating signaling mechanisms and the effects induced by synthetic compounds is through overexpression of recombinant reporter genes. Genome editing with CRISPR/Cas9 offers a means to better preserve native biology by appending reporters directly onto the endogenous genes. An optimal reporter for this purpose would be small to negligibly influence intracellular processes, be readily linked to the endogenous genes with minimal experimental effort, and be sensitive enough to detect low expressing proteins. HiBiT is a 1.3 kDa peptide (11 amino acids) capable of producing bright and quantitative luminescence through high affinity complementation (K_D = 700 pM) with an 18 kDa subunit derived from NanoLuc (LgBiT). Using CRISPR/Cas9, we demonstrate that HiBiT can be rapidly and efficiently integrated into the genome to serve as a reporter tag for endogenous proteins. Without requiring clonal isolation of the edited cells, we were able to quantify changes in abundance of the hypoxia inducible factor 1A (HIF1α) and several of its downstream transcriptional targets in response to various stimuli. In combination with fluorescent antibodies, we further used HiBiT to directly correlate HIF1α levels with the hydroxyproline modification that mediates its degradation. These results demonstrate the ability to efficiently tag endogenous proteins with a small luminescent peptide, allowing sensitive quantitation of the response dynamics in their regulated expression and covalent modifications.

Comparison of 12-month anatomic and functional results between Z6 femtosecond laser-assisted and manual trephination in deep anterior lamellar keratoplasty for advanced keratoconus

The management of severe keratoconus requires corneal transplantation, for which the gold standard is deep anterior lamellar keratoplasty (DALK), preserving the healthy Descemet's membrane and endothelium. The safety and reproducibility of corneal cuts have been improved by the evolution of femtosecond lasers in refractive surgery, and femtosecond laser in DALK would seem to provide the same advantages over the manual method. In our retrospective study, we compare functional and anatomical results of femtosecond-assisted DALK versus manual trephination DALK in patients with keratoconus in stage 4 of the Krumeich classification. It is a retrospective study including all patients with stage 4 keratoconus who underwent femtosecond laser-assisted DALK between November 2012 and November 2015 in Nantes university medical center. We compared those patients to a group of patients who underwent manual DALK in the same period, paired by age and maximal keratometry. We assessed visual acuity, pachymetry, endothelial cell density (specular microscopy), and keratometry before surgery and at 4, 8 and 12 months of follow-up. Laser settings and intraoperative complications were recorded. Nineteen patients underwent surgery by femtosecond-assisted DALK, 6 women and 12 men with average age 30.2±10.8 years at transplantation. They were paired with a group of 17 patients who underwent manual DALK in order to compare results. Before surgery, mean visual acuity in the femtosecond group was 0.90 logMAR versus 0.89 logMAR in the manual group, showing no statistically significant difference (P=0.96). Both groups were similar in terms of preoperative age, mean keratometry, pachymetry and endothelial cell density. Average visual acuity post-surgery was 0.27; 0.26; and 0.14 logMAR for femtosecond DALK versus 0.27; 0.17 et 0.25 for manual DALK at 4, 8 and 12 months follow-up respectively, showing no statistically significant difference. After surgery, at 4, 8 and 12 months, mean pachymetry was similar in both groups, and average endothelial cell density was 2390 cells/mm² for femto DALK versus 2531 cells/mm² for manual DALK at 12 months of follow-up, showing no statistically significant difference (P=0.5726). The rate of Descemet's membrane microperforations during the procedure was low and similar for both groups. Our study allows for a 12-month follow-up, with assessment of visual recovery, anatomic result and endothelial safety in a series of 19 femtosecond laser-assisted DALK with no statistical significant difference versus the manual trephination group. Femtosecond laser allows for increased reproducibility of the DALK procedure without reducing adverse effects during surgery. Femtosecond laser seems to improve the technique of the DALK procedure, and future developments could improve the reproducibility of DALK even further. A medical economics study would be necessary to determine the cost-effectiveness of femtosecond laser-assisted DALK.

Real-time analysis of the binding of fluorescent VEGF165a to VEGFR2 in living cells: Effect of receptor tyrosine kinase inhibitors and fate of internalized agonist-receptor complexes

Vascular endothelial growth factor (VEGF) is an important mediator of angiogenesis. Here we have used a novel stoichiometric protein-labeling method to generate a fluorescent variant of VEGF (VEGF₁₆₅a-TMR) labeled on a single cysteine within each protomer of the antiparallel VEGF homodimer. VEGF₁₆₅a-TMR has then been used in conjunction with full length VEGFR2, tagged with the bioluminescent protein NanoLuc, to undertake a real time quantitative evaluation of VEGFR2 binding characteristics in living cells using bioluminescence resonance energy transfer (BRET). This provided quantitative information on VEGF-VEGFR2 interactions. At longer incubation times, VEGFR2 is internalized by VEGF₁₆₅a-TMR into intracellular endosomes. This internalization can be prevented by the receptor tyrosine kinase inhibitors (RTKIs) cediranib, sorafenib, pazopanib or vandetanib. In the absence of RTKIs, the BRET signal is decreased over time as a consequence of the dissociation of agonist from the receptor in intracellular endosomes and recycling of VEGFR2 back to the plasma membrane.

Improved Deconvolution of Protein Targets for Bioactive Compounds Using a Palladium Cleavable Chloroalkane Capture Tag

The benefits provided by phenotypic screening of compound libraries are often countered by difficulties in identifying the underlying cellular targets. We recently described a new approach utilizing a chloroalkane capture tag, which can be chemically attached to bioactive compounds to facilitate the isolation of their respective targets for subsequent identification by mass spectrometry. The tag minimally affects compound potency and membrane permeability, enabling target engagement inside cells. Effective enrichment of these targets is achieved through selectivity in both their rapid capture onto immobilized HaloTag and their subsequent release by competitive elution. Here, we describe a significant improvement to this method where selective elution was achieved through palladium-catalyzed cleavage of an allyl-carbamate linkage incorporated into the chloroalkane capture tag. Selective tag cleavage provided robust release of captured targets exhibiting different modes of binding to the bioactive compound, including prolonged residence time and covalent interactions. Using the kinase inhibitors ibrutinib and BIRB796 as model compounds, we demonstrated the capability of this new method to identify both expected targets and "off-targets" exhibiting a range of binding affinities, cellular abundances, and binding characteristics.

NanoLuc Complementation Reporter Optimized for Accurate Measurement of Protein Interactions in Cells

Protein-fragment complementation assays (PCAs) are widely used for investigating protein interactions. However, the fragments used are structurally compromised and have not been optimized nor thoroughly characterized for accurately assessing these interactions. We took advantage of the small size and bright luminescence of NanoLuc to engineer a new complementation reporter (NanoBiT). By design, the NanoBiT subunits (i.e., 1.3 kDa peptide, 18 kDa polypeptide) weakly associate so that their assembly into a luminescent complex is dictated by the interaction characteristics of the target proteins onto which they are appended. To ascertain their general suitability for measuring interaction affinities and kinetics, we determined that their intrinsic affinity (KD = 190 μM) and association constants (kon = 500 M(-1) s(-1), koff = 0.2 s(-1)) are outside of the ranges typical for protein interactions. The accuracy of NanoBiT was verified under defined biochemical conditions using the previously characterized interaction between SME-1 β-lactamase and a set of inhibitor binding proteins. In cells, NanoBiT fusions to FRB/FKBP produced luminescence consistent with the linear characteristics of NanoLuc. Response dynamics, evaluated using both protein kinase A and β-arrestin-2, were rapid, reversible, and robust to temperature (21-37 °C). Finally, NanoBiT provided a means to measure pharmacology of kinase inhibitors known to induce the interaction between BRAF and CRAF. Our results demonstrate that the intrinsic properties of NanoBiT allow accurate representation of protein interactions and that the reporter responds reliably and dynamically in cells.

Deciphering the Cellular Targets of Bioactive Compounds Using a Chloroalkane Capture Tag

Phenotypic screening of compound libraries is a significant trend in drug discovery, yet success can be hindered by difficulties in identifying the underlying cellular targets. Current approaches rely on tethering bioactive compounds to a capture tag or surface to allow selective enrichment of interacting proteins for subsequent identification by mass spectrometry. Such methods are often constrained by ineffective capture of low affinity and low abundance targets. In addition, these methods are often not compatible with living cells and therefore cannot be used to verify the pharmacological activity of the tethered compounds. We have developed a novel chloroalkane capture tag that minimally affects compound potency in cultured cells, allowing binding interactions with the targets to occur under conditions relevant to the desired cellular phenotype. Subsequent isolation of the interacting targets is achieved through rapid lysis and capture onto immobilized HaloTag protein. Exchanging the chloroalkane tag for a fluorophore, the putative targets identified by mass spectrometry can be verified for direct binding to the compound through resonance energy transfer. Using the interaction between histone deacetylases (HDACs) and the inhibitor, Vorinostat (SAHA), as a model system, we were able to identify and verify all the known HDAC targets of SAHA as well as two previously undescribed targets, ADO and CPPED1. The discovery of ADO as a target may provide mechanistic insight into a reported connection between SAHA and Huntington's disease.

Selection of pairings reaching evenly across the data (SPREAD): A simple algorithm to design maximally informative fully crossed mating experiments

We present a novel algorithm for the design of crossing experiments. The algorithm identifies a set of individuals (a 'crossing-set') from a larger pool of potential crossing-sets by maximizing the diversity of traits of interest, for example, maximizing the range of genetic and geographic distances between individuals included in the crossing-set. To calculate diversity, we use the mean nearest neighbor distance of crosses plotted in trait space. We implement our algorithm on a real dataset of Neurospora crassa strains, using the genetic and geographic distances between potential crosses as a two-dimensional trait space. In simulated mating experiments, crossing-sets selected by our algorithm provide better estimates of underlying parameter values than randomly chosen crossing-sets.

NanoBRET--A Novel BRET Platform for the Analysis of Protein-Protein Interactions

Dynamic interactions between proteins comprise a key mechanism for temporal control of cellular function and thus hold promise for development of novel drug therapies. It remains technically challenging, however, to quantitatively characterize these interactions within the biologically relevant context of living cells. Although, bioluminescence resonance energy transfer (BRET) has often been used for this purpose, its general applicability has been hindered by limited sensitivity and dynamic range. We have addressed this by combining an extremely bright luciferase (Nanoluc) with a means for tagging intracellular proteins with a long-wavelength fluorophore (HaloTag). The small size (19 kDa), high emission intensity, and relatively narrow spectrum (460 nm peak intensity) make Nanoluc luciferase well suited as an energy donor. By selecting an efficient red-emitting fluorophore (635 nm peak intensity) for attachment onto the HaloTag, an overall spectral separation exceeding 175 nm was achieved. This combination of greater light intensity with improved spectral resolution results in substantially increased detection sensitivity and dynamic range over current BRET technologies. Enhanced performance is demonstrated using several established model systems, as well as the ability to image BRET in individual cells. The capabilities are further exhibited in a novel assay developed for analyzing the interactions of bromodomain proteins with chromatin in living cells.

Abstract 1998: A novel luminescent system for monitoring intracellular protein:protein interactions

Protein:protein interactions (PPIs) are essential to the cellular signal transduction pathways that contribute to cancer. Although numerous approaches exist to monitor protein:protein interactions in vitro, methods for intracellular detection have been more limited. We developed a system for the detection of PPIs based on NanoLuc luciferase. Proteins are fused to either an 18 kDa or 1 kDa subunit. PPI facilitates interaction of the subunits, leading to increased luminescence. Intracellular PPIs are measured using a non-lytic assay protocol by providing a cell permeable substrate. The interaction status can be monitored at a single time point or followed continuously over 1-2 hours. Unlike related approaches where a luciferase enzyme is simply split, the subunits of this system were optimized for structural stability and minimal binding affinity. The result is a luminescence signal that is orders of magnitude brighter than approaches using split luciferase, allowing use of fusion protein expression levels at or near physiological levels. The low affinity interaction between subunits (Kd ∼200 μM) minimizes assay background by preventing non-specific association, and the system shows rapid reversibility using model systems such as protein kinase A catalytic and regulatory subunits. We have successfully applied this system to several PPIs related to cancer research, including TP53:MDM2, MYC:MAX, and members of the RAS-RAF signaling pathway.

Citation Format: Brock Binkowski, Andrew S. Dixon, Marie K. Schwinn, Mary P. Hall, Kris Zimmerman, Paul Otto, Thomas Lubben, Braeden Butler, Thomas Kirkland, Monika G. Wood, Lance P. Encell, Frank Fan, Keith V. Wood. A novel luminescent system for monitoring intracellular protein:protein interactions. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1998. doi:10.1158/1538-7445.AM2015-1998

Abstract 3512: Measuring intracellular target engagement and drug residence time with nanoBRET

We present a biophysical method to directly measure target engagement within intact mammalian cells using bioluminescence energy transfer (BRET). Compound interactions with intracellular targets can be detected with complete specificity by their ability to compete with energy transfer complexes introduced into the cells. These complexes can be detected at physiologically relevant levels by exploiting an extraordinarily bright luciferase (NanoLuc), together with fluorescent tracers optimized for cell-permeability and spectral resolution from the luciferase. We demonstrate applications of the technology for target engagement among key drug target classes, including; kinases, histone deacetylases (HDACs), bromodomains, and the methyltransferase EZH2. Intracellular selectivity and affinity profiles of various reference compounds and approved drugs will be presented. For a panel of HDAC inhibitors, affinity profiles for specific HDAC isozymes strongly correlate with phenotypic potencies (e.g. cell viability). Furthermore, the luminescent output of the energy transfer complex enables a technique to monitor ligand occupancy in real-time. Association and dissociation rates can be derived from the kinetic measurements, providing a means to quantify drug residence time on select targets within intact cell populations. This novel application of intracellular BRET should significantly advance target engagement work flows, and allow for intracellular target affinities to be coupled to phenotypic outcomes.

Citation Format: Matthew B. Robers, Melanie Dart, Chad Zimprich, Thomas Kirkland, Sergiy Levin, Thomas Machleidt, Jim Hartnett, Kris Zimmerman, Rachel Ohana, Danette Daniels, Mei Cong, Frank Fan, Keith Wood. Measuring intracellular target engagement and drug residence time with nanoBRET. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3512. doi:10.1158/1538-7445.AM2015-3512

Real-time, high-resolution x-ray diffraction measurements on shocked crystals at a synchrotron facility

The Advanced Photon Source (APS) at Argonne National Laboratory was used to obtain real-time, high-resolution x-ray diffraction measurements to determine the microscopic response of shock-compressed single crystals. Disk shaped samples were subjected to plane shock wave compression by impacting them with half-inch diameter, flat-faced projectiles. The projectiles were accelerated to velocities ranging between 300 and 1200 m/s using a compact powder gun designed specifically for use at a synchrotron facility. The experiments were designed to keep the sample probed volume under uniaxial strain and constant stress for a duration longer than the 153.4 ns spacing between x-ray bunches. X-rays from a single pulse (<100 ps duration) out of the periodic x-ray pulses emitted by the synchrotron were used for the diffraction measurements. A synchronization and x-ray detection technique was developed to ensure that the measured signal was obtained unambiguously from the desired x-ray pulse incident on the sample while the sample was in a constant uniaxial strain state. The synchronization and x-ray detection techniques described can be used for a variety of x-ray measurements on shock compressed solids and liquids at the APS. Detailed procedures for applying the Bragg-Brentano parafocusing approach to single crystals at the APS are presented. Analytic developments to determine the effects of crystal substructure and non-ideal geometry on the diffraction pattern position and shape are presented. Representative real-time x-ray diffraction data, indicating shock-induced microstructural changes, are presented for a shock-compressed Al(111) sample. The experimental developments presented here provided, in part, the impetus for the Dynamic Compression Sector (DCS) currently under development at the APS. Both the synchronization∕x-ray detection methods and the analysis equations for high-resolution single crystal x-ray diffraction can be used at the DCS.

Development of a dehalogenase-based protein fusion tag capable of rapid, selective and covalent attachment to customizable ligands

Our fundamental understanding of proteins and their biological significance has been enhanced by genetic fusion tags, as they provide a convenient method for introducing unique properties to proteins so that they can be examinedin isolation. Commonly used tags satisfy many of the requirements for applications relating to the detection and isolation of proteins from complex samples. However, their utility at low concentration becomes compromised if the binding affinity for a detection or capture reagent is not adequate to produce a stable interaction. Here, we describe HaloTag® (HT7), a genetic fusion tag based on a modified haloalkane dehalogenase designed and engineered to overcome the limitation of affinity tags by forming a high affinity, covalent attachment to a binding ligand. HT7 and its ligand have additional desirable features. The tag is relatively small, monomeric, and structurally compatible with fusion partners, while the ligand is specific, chemically simple, and amenable to modular synthetic design. Taken together, the design features and molecular evolution of HT7 have resulted in a superior alternative to common tags for the overexpression, detection, and isolation of target proteins.

Abstract 151: Advancing pathway analysis using bioluminescent reporters

To enable investigation of key cellular signaling pathways, Promega has developed a portfolio of bioluminescent reporter gene assays using Firefly and Renilla luciferases. In combination with best-in-class luciferase detection reagents, these genetic reporter systems enable interrogation of important cellular responses involved in cancer, inflammation, and CNS disease. To address specialized customer needs in our industrial and research markets, Promega has a new custom assay service team dedicated to applying these enabling technologies through strategic external research collaborations. The performance of this technology portfolio is presented, including novel applications of luciferase reporters to interrogation of cytokine, stress, and toxicity pathway responses.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 151. doi:1538-7445.AM2012-151

A luminescent biosensor with increased dynamic range for intracellular cAMP

The second messenger cAMP is a key mediator of signal transduction following activation of G-protein coupled receptors. Investigations on Gs-coupled receptors would benefit from a second messenger assay that allows continuous monitoring of kinetic changes in cAMP concentration over a broad dynamic range. To accomplish this, we have evolved a luminescent biosensor for cAMP to better encompass the physiological concentration ranges present in living cells. When compared to an immunoassay, the evolved biosensor construct was able to accurately track both the magnitude and kinetics of cAMP change using a far less labor intensive format. We demonstrate the utility of this construct to detect a broad range of receptor activity, together with showing suitability for use in high-throughput screening.

HaloTag: a novel protein labeling technology for cell imaging and protein analysis

We have designed a modular protein tagging system that allows different functionalities to be linked onto a single genetic fusion, either in solution, in living cells, or in chemically fixed cells. The protein tag (HaloTag) is a modified haloalkane dehalogenase designed to covalently bind to synthetic ligands (HaloTag ligands). The synthetic ligands comprise a chloroalkane linker attached to a variety of useful molecules, such as fluorescent dyes, affinity handles, or solid surfaces. Covalent bond formation between the protein tag and the chloroalkane linker is highly specific, occurs rapidly under physiological conditions, and is essentially irreversible. We demonstrate the utility of this system for cellular imaging and protein immobilization by analyzing multiple molecular processes associated with NF-kappaB-mediated cellular physiology, including imaging of subcellular protein translocation and capture of protein--protein and protein--DNA complexes.

Neurological effects of acute uranium exposure with and without stress

Circulating uranium rapidly enters the brain and may cause adverse effects on the nervous system that are potentially modulated by stress. In this study, the neurological effects of a single intramuscular injection of 0, 0.1, 0.3, or 1 mg uranium/kg (as uranyl acetate, UA) in rats were examined in the presence and absence of stress. Treatment with UA produced time and dose-dependent increases in serum and regional brain uranium levels. While serum levels returned to control levels by day 30, brain levels remained elevated. Application of stress did not affect the distribution or retention of uranium. Exposure to 1 mg U/kg significantly decreased ambulatory activity, weight gain, forelimb grip strength and transiently impaired working memory. Effects on grip strength and memory were prevented by application of stress prior to uranium exposure. Striatal dopamine content was reduced by 30% 3 days after treatment with 1mg/kg (59+/-6 nmol/mg tissue versus 41+/-5 nmol/mg tissue), but levels returned to control 7 days after uranium exposure. The effect on dopamine was ameliorated by prior application of stress. Exposure to UA did not alter 3,4 dihydroxyphenylacetic acid (DOPAC) levels or numbers of D2 receptors in the striatum. No effect of uranium or stress was observed on levels of GABA, serotonin, norepinephrine, or glutathione (GSH) in the striatum, hippocampus, cerebellum, or cortex. These results indicate that single intramuscular exposures to uranium produce sustained elevation of brain uranium levels and at doses above 0.3 mg/kg can have adverse neurological effects. Application of stress prior to uranium administration modulates neurological effects, but the mechanism is not due to effects on uranium distribution. Uranium exposure also produced renal toxicity which must be considered to accurately assess the effects of uranium on neurological function.

Intestinal carriage of Campylobacter jejuni and Campylobacter coli among cattle from south-western Norway and comparative genotyping of bovine and human isolates by amplified-fragment length polymorphism

In a survey conducted in 1999-2001, the carriage of thermotolerant Campylobacters in cattle was investigated, and the genetic diversity of C. jejuni within one herd was examined and compared with human isolates. C. jejuni, C. coli and other thermotolerant Campylobacter spp. were isolated from intestinal contents from 26%, 3% and 2% of 804 cattle, respectively. The carriage rate was higher in calves (46%) than in adults (29%). Twenty-nine C. jejuni isolates from one herd and 31 human isolates from the study area were genotyped with amplified-fragment length polymorphism (AFLP). Eighty-three % of the bovine isolates fell into three distinct clusters with 95-100% similarity, persistent in the herd for 5-10 months. Among human isolates, 58% showed >90% similarity with bovine isolates. The results show that cattle are a significant and stable reservoir for C. jejuni in the study area. Transmission between individuals within the herd may be sufficient to maintain a steady C. jejuni population independent of environmental influx. The results of this study have provided new information on C. jejuni and C. coli transmission, and also on the carriage in cattle, genotypes stability and similarity between bovine and human isolates.

Molecular and clinical characteristics of respiratory syncytial virus infections in hospitalized children

The objective of this study was to determine the importance of respiratory syncytial virus (RSV) for hospitalization in the north east of Germany and to obtain molecular epidemiological data of the circulating strains. Using a rapid and sensitive reverse transcriptase-PCR, it was found that a quarter of pediatric respiratory disease admissions were due to RSV. Infections caused by RSV in hospitalized patients were determined over the whole year. Both RSV groups A and B were identified with a predominance of RSV A (86%) over the entire period. The analysis of the deduced amino acid sequences by direct sequencing showed that very similar RSV strains are circulating in the community.

Central mineralocorticoid receptor blockade improves volume regulation and reduces sympathetic drive in heart failure

The mineralocorticoid (MC) receptor antagonist spironolactone (SL) improves morbidity and mortality in patients with congestive heart failure (CHF). We tested the hypothesis that the central nervous system actions of SL contribute to its beneficial effects. SL (100 ng/h for 28 days) or ethanol vehicle (VEH) was administered intracerebroventricularly or intraperitoneally to rats with CHF induced by coronary artery ligation (CL) and to SHAM-operated controls. The intracerebroventricular SL treatment prevented the increase in sodium appetite and the decreases in sodium and water excretion observed within a week of CL in VEH-treated CHF rats. Intraperitoneal SL also improved volume regulation in the CHF rats, but only after 3 wk of treatment. Four weeks of SL treatment, either intracerebroventricularly or intraperitoneally, ameliorated both the increase in sympathetic drive and the impaired baroreflex function observed in VEH-treated CHF rats. These findings suggest that activation of MC receptors in the central nervous system plays a critical role in the altered volume regulation and augmented sympathetic drive that characterize clinical heart failure.

Clinical significance of the preoperative plasma carcinoembryonic antigen (CEA) level in patients with carcinoma of the large bowel

Preoperative levels of perchloric acid extractable plasma CEA were measured in 911 patients with complaints of the digestive system. A final diagnosis of benign disease was made for 579 patients; 332 patients were found to have cancer. Data for the preoperative CEA values were examined for clinical significance as an aide to diagnosis, preoperative disease staging, and prognosis. The results of our analysis support the conclusions of many investigators that the CEA assay is not a clinically useful diagnostic test, but it shows limited value in preoperative staging and a somewhat stronger correlation with prognosis.

The homeodomain-containing gene Xdbx inhibits neuronal differentiation in the developing embryo

The development of the vertebrate nervous system depends upon striking a balance between differentiating neurons and neural progenitors in the early embryo. Our findings suggest that the homeodomain-containing gene Xdbx regulates this balance by maintaining neural progenitor populations within specific regions of the neuroectoderm. In posterior regions of the Xenopus embryo, Xdbx is expressed in a bilaterally symmetric stripe that lies at the middle of the mediolateral axis of the neural plate. This stripe of Xdbx expression overlaps the expression domain of the proneural basic/helix-loop-helix-containing gene, Xash3, and is juxtaposed to the expression domains of Xenopus Neurogenin related 1 and N-tubulin, markers of early neurogenesis in the embryo. Xdbx overexpression inhibits neuronal differentiation in the embryo and when co-injected with Xash3, Xdbx inhibits the ability of Xash3 to induce ectopic neurogenesis. One role of Xdbx during normal development may therefore be to restrict spatially neuronal differentiation within the neural plate, possibly by altering the neuronal differentiation function of Xash3.

Cardiac hypertrophy is not a required compensatory response to short-term pressure overload

BACKGROUND

Cardiac hypertrophy is considered a necessary compensatory response to sustained elevations of left ventricular (LV) wall stress.

METHODS AND RESULTS

To test this, we inhibited calcineurin with cyclosporine (CsA) in the setting of surgically induced pressure overload in mice and examined in vivo parameters of ventricular volume and function using echocardiography. Normalized heart mass increased 45% by 5 weeks after thoracic aortic banding (TAB; heart weight/body weight, 8.3+/-0.9 mg/g [mean+/-SEM] versus 5. 7+/-0.1 mg/g unbanded, P<0.05). Similar increases were documented in the cell-surface area of isolated LV myocytes. In mice subjected to TAB+CsA treatment, we observed complete inhibition of hypertrophy (heart weight/body weight, 5.2+/-0.3 mg/g at 5 weeks) and myocyte surface area (endocardial and epicardial fractions). The mice tolerated abolition of hypertrophy with no signs of cardiovascular compromise, and 5-week mortality was not different from that of banded mice injected with vehicle (TAB+Veh). Despite abolition of hypertrophy by CsA (LV mass by echo, 83+/-5 mg versus 83+/-2 mg unbanded), chamber size (end-diastolic volume, 33+/-6 microL versus 37+/-1 microL unbanded), and systolic ejection performance (ejection fraction, 97+/-2% versus 97+/-1% unbanded) were normal. LV mass differed significantly in TAB+Veh animals (103+/-5 mg, P<0.05), but chamber volume (end-diastolic volume, 44+/-6 microL), ejection fraction (92+/-2%), and transstenotic pressure gradients (70+/-14 mm Hg in TAB+Veh versus 77+/-11 mm Hg in TAB+CsA) were not different.

CONCLUSIONS

In this experimental setting, calcineurin blockade with CsA prevented LV hypertrophy due to pressure overload. TAB mice treated with CsA maintain normal LV size and systolic function.

Electrophysiological characterization of CGP68730A a N-methyl-D-aspartate antagonist acting at the strychnine-insensitive glycine site

1. Electrophysiological experiments were performed in vitro and in vivo. Voltage clamp recordings were done in Xenopus oocytes. Extracellular recordings were done in vitro in the neocortical slice and in the CA1 region of the hippocampal slice and in vivo in the CA1 region of the hippocampus of the anaesthetized rat. 2. In oocytes expressing either the human NMDAR1A/2A or 1A/2B subunit combinations, CGP68730A [sodium (-)-9-bromo-2,3,6,7-tetrahydro-5,6-dioxo-5H-pyrazino[1,2,3-de]-1,4-benzo thiazine-3-acetic acid] antagonized L-glutamate / glycine induced currents with calculated IC50s of 20.5 and 81.6 nM, respectively. 3. In vitro, CGP68730A was tested on NMDA induced depolarizations in the neocortical slice preparation and on epileptiform activity in hippocampal slices bathed in Mg2+-free-medium, which is known to be NMDA mediated. In both in vitro models CGP68730A exhibited antagonistic effects on the NMDA receptor mediated responses. 4. In vivo CGP68730A was tested on NMDA induced excitations in the CA1 region. CGP68730A abolished NMDA induced excitations when applied microiontophoretically. However, only weak effects on NMDA induced excitation were observed after systemic administration at 100 mg/kg i.v.. These results indicate that CGP68730A has poor central nervous system bioavailability. 5. In oocytes, an increase in the glycine concentration from the EC80 to the EC95.99 shifted the inhibition curves for CGP68730A to the right. Furthermore, in neocortical slices and in anaesthetized rats CGP68730A inhibited NMDA mediated depolarizations, and this effect could be reversed by the addition of the glycine mimetic D-serine. This indicates that these effects of CGP68730A are mediated by an action on the strychnine-insensitive glycine site. 6. Selectivity tests in oocytes and in the neocortical slice preparation, using NMDA, kainate and AMPA showed that CGP68730A was selective in antagonizing NMDA receptor mediated responses. In oocytes, the compound was about 1000 times less potent on the rat GluR3 and the human GluR6 receptors than on the human NMDAR1A/2A subunit combination. In the neocortical slice preparationCGP68730A had no effects on AMPA or kainate induced depolarizations at concentrations of 3 and 10 microM. At 30 microM CGP68730A reduced the effects of each of the three agonists tested. 7. Thus, CGP68730A seems to be a selective antagonist at the strychnine-insensitive glycine coagonist site of the NMDA receptor. However, the compound showed no obvious central NMDA antagonistic effects following intravenous application.

Age-related deterioration of motion perception and detection

PURPOSE

The purpose of this study was to evaluate the effect of aging on motion detection and perception.

METHODS

Forty-six subjects, ages 19-92 years, were asked to view a motion stimulus. Infrared oculography was used to objectively evaluate motion detection by documenting the presence of optokinetic nystagmus as the subjects viewed the stimulus. Subjective responses to motion perception were recorded using a computer joystick.

RESULTS

Optokinetic nystagmus was clearly detectable in all 46 subjects. Motion detection and perception thresholds showed age-related deterioration. No relationship was found to gender or age-gender interaction.

CONCLUSION

The results indicate motion detection and perception thresholds deteriorate with age. This may reflect a susceptibility to age-related degeneration in specific cortical areas responsible for motion perception as well as neurodegeneration in the retinogeniculate pathway.

XATH-1, a vertebrate homolog of Drosophila atonal, induces a neuronal differentiation within ectodermal progenitors

XATH-1, a basic/helix-loop-helix transcription factor and a homolog of Drosophila atonal and mammalian MATH-1, is expressed specifically in the dorsal hindbrain during Xenopus neural development. In order to investigate the role of XATH-1 in the neuronal differentiation process, we have examined the effects of XATH-1 overexpression during Xenopus development. XATH-1 induces the expression of neuronal differentiation markers, such as N-tubulin, within the neural plate as well as within nonneural ectodermal progenitor populations, resulting in the appearance of process-bearing neurons within the epidermis. The related basic/helix-loop-helix genes neurogenin-related-1 and neuroD are not induced in response to XATH-1 overexpression within the embryo, suggesting that XATH-1 may activate an alternate pathway of neuronal differentiation. In further contrast to neurogenin-related-1 and neuroD, high-level expression of general neural markers expressed earlier in development, such as N-CAM, is not induced by XATH-1 overexpression. Competent ectodermal progenitors therefore respond to ectopic XATH-1 expression by initiating a distinct program of neuronal differentiation.

Differential prenyl pyrophosphate binding to mammalian protein geranylgeranyltransferase-I and protein farnesyltransferase and its consequence on the specificity of protein prenylation

Protein geranylgeranyltransferase-I (PGGT-I) and protein farnesyltransferase (PFT) attach geranylgeranyl and farnesyl groups, respectively, to the C termini of eukaryotic cell proteins. In vitro, PGGT-I and PFT can transfer both geranylgeranyl and farnesyl groups from geranylgeranyl pyrophosphate (GGPP) and farnesyl pyrophosphate (FPP) to their protein or peptide prenyl acceptor substrates. In the present study it is shown that PGGT-I binds GGPP 330-fold tighter than FPP and that PFT binds FPP 15-fold tighter than GGPP. Therefore, in vivo, where both GGPP and FPP compete for the binding to prenyltransferases, PGGT-I and PFT will likely be bound predominantly to GGPP and FPP, respectively. Previous studies have shown that K-Ras4B and the Ras-related GTPase TC21 are substrates for both PGGT-I and PFT in vitro. It is shown that TC21 can compete with the C-terminal peptide of the gamma subunit of heterotrimeric G proteins and with the C-terminal peptide of lamin B for geranylgeranylation by PGGT-I and for farnesylation by PFT, respectively. K-Ras4B competes in both cases but is almost exclusively farnesylated by PFT in the presence of the lamin B peptide competitor. Rapid and single turnover kinetic studies indicate that the rate constant for the PGGT-I-catalyzed geranylgeranyl transfer step of the reaction cycle is 14-fold larger than the steady-state turnover number, which indicates that the rate of the overall reaction is limited by a step subsequent to prenyl transfer such as release of products from the enzyme. PGGT-I-catalyzed farnesylation is 37-fold slower than geranylgeranylation and is limited by the farnesyl transfer step. These results together with earlier studies provide a paradigm for the substrate specificity of PGGT-I and PFT and provide information that is critical for the design of prenyltransferase inhibitors as anti-cancer agents.

Genes involved in cerebellar cell specification and differentiation

The conservation of transcriptional regulatory mechanisms across species, combined with the restricted expression of these molecules in time and space within the embryo, has offered new insights into CNS cell specification. Studies examining transcriptional control in the generation of specific cell classes within the cerebellar cortex have been particularly elucidative.

Comparison of visual function in fellow eyes after bilateral nonarteritic anterior ischemic optic neuropathy

PURPOSE

Although previous studies have examined the risk of bilaterality of nonarteritic ischemic optic neuropathy (NAION), none have compared extensively the extent of visual loss between fellow eyes. The authors examined cases of bilateral NAION to determine the extent of vision loss in the second eye compared with that in the first eye.

METHODS

Thirty-one cases of bilateral NAION were reviewed. Variables included age, gender, and the presence of comorbid disease. Visual function was assessed by Snellen visual acuity, color vision, and pattern and mean deviation of the visual fields.

RESULTS

No correlation was detected between the extent or pattern of visual loss in fellow eyes. No significant difference in visual function existed between first and second eyes for the patients overall. Patients who retained better visual function in the second eye were significantly older than those who retained better visual function in the first eye (visual acuity, P = 0.0005; color vision, P = 0.07; mean deviation, P = 0.02). In patients older than 50 years of age (25 of 31 cases), the second eye had significantly better visual acuity (P = 0.04) and less Humphrey visual field mean deviation (P = 0.04) than the first eye.

CONCLUSION

Visual function in the second eye correlated poorly with that of the first eye. Older patients with bilateral NAION retained better visual function in the second eye than in the first eye. For younger patients, the extent of visual loss in the second eye could not be predicted based on the visual loss in the first eye.

Effect of celiac ganglionectomy on tachykinin innervation, receptor distribution and intestinal responses in the rat

Substance P (SP) is an important neurotransmitter in the control of intestinal motility and is found in both the enteric and sympathetic nervous systems. This study examined the effect of celiac ganglionectomy on (1) mechanical properties of the circular muscles of the duodenum, ileum and proximal colon, (2) circular muscle responses to SP and neurokinin A. (3) distribution of substance P-like immunoreactive nerves, and (4) the distribution of neurokinin 1 and neurokinin 2 receptors. Celiac ganglionectomy resulted in an effective sympathectomy as evidenced by a marked decrease in norepinephrine content and tyrosine hydroxylase staining in the duodenum, ileum and proximal colon. The in vitro length/tension characteristics of the circular muscle of the duodenum, ileum and colon were unchanged after ganglionectomy. In all regions of the gut studied, substance P and neurokinin A caused dose-dependent contractions that were unaltered by celiac ganglionectomy. Immunohistochemistry revealed moderate substance P-like immunoreactive fibers in the myenteric plexus, submucosal plexus and circular muscle of the ileum, while in the colon, substance P-like immunoreactivity was intense in the myenteric plexus, and moderate in the circular muscle. In vitro autoradiography showed minimal binding of SP (NK1 receptor) or neurokinin A (NK2 receptor) in the ileum and significantly greater binding in the circular muscle layer of the colon. Celiac ganglionectomy did not affect substance P-like immunoreactivity, or NK1 or NK2 receptor binding. A greater contractile response to neurokinins was seen in the colon than in the duodenum or ileum, which paralleled the receptor density. The studies demonstrate that surgical celiac ganglionectomy, unlike chemical sympathectomy, does not affect the substance P innervation, receptor density or physiological responses of the intestine. The greater contractile response of the colon than the ileum parallels the greater receptor density rather than the peptide content as determined by immunhistochemistry.

Diverticular bleeding and the pigmented protuberance (sentinel clot): clinical implications, histopathological correlation, and results of endoscopic intervention

Over a 3-yr period, we performed colonoscopy on five patients (mean age 71 yr) in whom a specific diverticulum that contained a pigmented protuberance (PiP) was unequivocally identified as the cause for hemorrhage. Four of these individuals had endoscopic bipolar cauterization of the PiP, and two patients had surgery.

AIM

To (1) determine the clinical significance of an intradiverticular PiP, (2) correlate endoscopic features of a PiP with histopathological findings and, (3) assess results of endoscopic treatment for affected patients with lower GI bleeding.

METHODS

Medical charts were reviewed to garner data and assess outcome for patients. The bleeding diverticulum in one surgical case was detected in the resected specimen, and histological examination was performed.

RESULTS

The mean number of transfusions, bleeding days, and lowest hemoglobin concentration before definitive treatment was 4.8, 3.4, and 8.4 gm%, respectively. All patients rebled before treatment. In all instances, the PiP projected through the neck of the diverticulum, which was actively bleeding in two patients. Endoscopic bipolar cautery directed at the PiP achieved permanent hemostasis in three of four subjects (75%) (morbidity 0%). Endoscopic therapy failed in one subject, and a hemicolectomy was performed. Histological evaluation of the resected specimen showed erosion of a medium sized artery into the diverticulum. The PiP represented a sentinel clot (not a visible vessel) adherent to a breach in the vessel wall. A patient who had surgery instead of endoscopic therapy had a prolonged, complicated postoperative course.

CONCLUSIONS

(1) The presence of an intradiverticular PiP may identify a subset of patients at risk for severe recurrent diverticular bleeding. (2) Histopathological analysis showed the PiP to be a sentinel clot rather than a visible vessel. (3) In patients with severe recurrent diverticular bleeding, endoscopic treatment of the vessel beneath this lesion may be a viable alternative to surgery.

Two-year outcome of social skills training and group psychotherapy for outpatients with schizophrenia

OBJECTIVE

The authors evaluated the effectiveness of behaviorally oriented social skills training and supportive group therapy for improving the social adjustment of schizophrenic patients living in the community and for protecting them against psychotic relapse.

METHOD

Eighty male outpatients with schizophrenia were stabilized with a low dose of fluphenazine decanoate (5 to 10 mg every 14 days), which was supplemented with oral fluphenazine (5 mg twice daily) or a placebo when they first met criteria for a prodromal period. (Half of the patients did so at some time during the study.) Patients were randomly assigned to receive either social skills training or supportive group therapy twice weekly for 6 months and then weekly for the next 18 months. Rates of psychotic exacerbation were monitored, as were scores on the Social Adjustment Scale II.

RESULTS

There were significant main effects favoring social skills training over supportive group therapy on two of the six Social Adjustment Scale II cluster totals examined (personal well-being and total) and significant interactions between psychosocial treatment and drug treatment for three items (external family, social and leisure activities, and total). In each case, these interactions indicated that the advantage of social skills training over supportive group therapy was greatest when it was combined with active drug supplementation. Social skills training did not significantly decrease the risk of psychotic exacerbation in the full group, but an advantage was observed (post hoc) among patients who received placebo supplementation.

CONCLUSIONS

These findings suggest that social skills training resulted in greater improvement in certain measures of social adjustment than supportive group therapy. The greatest improvement in social outcomes occurred when social skills training was combined with a pharmacological strategy of active drug supplementation at the time prodromal worsening of psychotic symptoms was first observed. However, these improvements were modest in absolute terms and confined to certain subgroups of patients.