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Drug resistance is prevalent across many diseases, rendering therapies ineffective with severe financial and health consequences. Rather than accepting resistance after the fact, proactive strategies need to be incorporated into the drug design and development process to minimize the impact of drug resistance. These strategies can be derived from our experience with viral disease targets where multiple generations of drugs had to be developed to combat resistance and avoid antiviral failure. Significant efforts including experimental and computational structural biology, medicinal chemistry, and machine learning have focused on understanding the mechanisms and structural basis of resistance against direct-acting antiviral (DAA) drugs. Integrated methods show promise for being predictive of resistance and potency. In this review, we give an overview of this research for human immunodeficiency virus type 1, hepatitis C virus, and influenza virus and the lessons learned from resistance mechanisms of DAAs. These lessons translate into rational strategies to avoid resistance in drug design, which can be generalized and applied beyond viral targets. While resistance may not be completely avoidable, rational drug design can and should incorporate strategies at the outset of drug development to decrease the prevalence of drug resistance.

Background Conventional first-line combination therapy for ovarian cancer comprises 6 cycles of adjuvant or neoadjuvant carboplatin (AUC5-6) with paclitaxel (175 mg/m2) every 3 weeks (PC-3W). Weekly scheduling of paclitaxel may maximize its antiangiogenic effect and reduce adverse effects. We compared the efficacy and safety of PC-3W with a modified protocol of weekly paclitaxel 80 mg/m2 and weekly carboplatin AUC2 administered on days 1, 8, and 15 in a 28-day cycle (i.e., with 1 week off-treatment [PC-W]). Materials and Methods Medical records of consecutive patients treated between 2000 and 2018 were reviewed; 707 patients were analyzed for demographic and clinical characteristics, effectiveness and toxicity. Results PC-3W was administered to 402 patients (median age, 60.5 years) and PC-W to 305 patients (median age, 62.5 years). Most patients (91.4%) were diagnosed at stage III–IV. Notwithstanding a higher proportion of residual disease and older patients in the PC-W group, median progression-free survival was 21.4 months and 13.2 months for PC-W and PC-3W, respectively; median overall survival was 75.2 and 54.0 months for PC-W and PC-3W, respectively. Cox proportional hazards model indicated improved survival for patients treated with PC-W (hazard ratio, 0.54). Similar results were observed for older patients diagnosed at ≥75 years. PC-W demonstrated a better safety profile, with lower incidence of neuropathy, neutropenia, and alopecia. Conclusion PC-W is as active and better tolerated than the standard PC-3W regimen. PC-W may serve as an alternative option for elderly or frail patients. Implications for Practice Weekly scheduling of paclitaxel 80 mg/m2 and carboplatin AUC2, administered on days 1, 8, and 15 in a 28-day cycle (PC-W) for first-line therapy for advanced ovarian cancer, is as active and better tolerated than the standard regimen of carboplatin and paclitaxel (175 mg/m2) every 3 weeks (PC-3W). It is possible that the weekly holiday on day 21 in the PC-W regimen may ensure better completion rates (which may result in treatment delays for toxicity in PC-3W). The results of this retrospective analysis highlight the weekly regimen as a valid treatment option, especially for elderly patients and those with significant comorbidities.

Quality Assurance (QA) in hadron therapy is crucial to ensure safe and accurate dose delivery to patients. This can be achieved with fast, reliable and high-resolution detectors. In this paper, we present a novel solution that combines a triple Gas Electron Multiplier (GEM) and a highly pixelated readout based on a matrix of organic photodiodes fabricated on top of an oxide-based thin-film transistor backplane. The first LaGEMPix prototype with an active area of 60 × 80 mm2 was developed and characterized using low energy X-rays. The detector comprises a drift gap of 3.5 mm, a triple-GEM stack for electron amplification, and a readout featuring 480 × 640 pixels at a 126 µm pitch. Here, we describe the measurements and results in terms of spatial resolution for various experimental configurations. A comparison with GAFCHROMIC® films and the GEMPix detector used in the charge readout mode was performed to better understand the contribution to the spatial resolution from both the electron diffusion and the isotropic emission of photons. The measurements were compared to Monte Carlo simulations, using the FLUKA code. The simulation predictions are in good agreement with the GEMPix results. Future plans with respect to applications in hadron therapy are discussed.

Casein is a group of milk proteins with high nutritional value, and the exploitation of its techno-functional potentials has been investigated for decades. In this study, acid casein powder was dissolved in 0.1 mol/L phosphate buffers with different pH, resulting in casein solutions with pH 5.9, 6.6 and 7.3. During preparation and storage (40 °C) of the samples, casein hydrolysis was observed in size exclusion chromatography and gel electrophoresis. The degree of hydrolysis increased with increasing pH, and treatment of casein with commercial plasmin resulted in similar polypeptides, suggesting that the hydrolysis was caused by residual indigenous plasmin present in the acid casein powder. Most polypeptides could be cross-linked by microbial transglutaminase, except for one particular fraction which appeared at constant intensity in the chromatograms. The stiffness of acid-induced gels as determined in small amplitude oscillatory shear rheology decreased with increasing degree of hydrolysis, and was also lower for cross-linked samples when the preceding casein hydrolysis was more pronounced. Enzymatic cross-linking increased the resistance of casein against plasmin-related hydrolysis, presumably because of the resulting lysine modification. However, one particular fraction of polypeptides was released by hydrolysis in spite of cross-linking, suggesting that they did not contain lysine residues that are susceptible for mTGase. The results indicate that plasmin-related hydrolysis should be taken into account for the application of acid casein or sodium caseinate as additive in food design.

Drug resistance threatens many critical therapeutics through mutations in the drug target. The molecular mechanisms by which combinations of mutations, especially involving those distal from the active site, alter drug binding to confer resistance are poorly understood and thus difficult to counteract. A machine learning strategy was developed that couples parallel molecular dynamics simulations and experimental potency to identify specific conserved mechanisms underlying resistance. A series of 28 HIV-1 protease variants with 0-24 substitutions each were used as a rigorous model of this strategy. Many of the mutations were distal from the active site and the potency of variants to a drug (darunavir) varied from low picomolar to near micromolar. With features extracted from the simulations, elastic network machine learning was applied to correlate physical interactions with loss of potency and succeeded to within 1 kcal/mol of experimental affinity for both the training and test sets, outperforming MM/GBSA calculations. Feature reduction resulted in a model with 4 specific features that describe interactions critical for potency for all 28 variants. These predictive features, that specifically vary with potency, occur throughout the enzyme and would not have been identified without dynamics and machine learning. This strategy thus captures the conserved dynamic mechanisms by which complex combinations of mutations confer resistance and identifies critical features that serve as bellwethers of loss of inhibitor potency. Machine learning models leveraging molecular dynamics can thus elucidate mechanisms of drug resistance that confer loss of affinity and will serve as predictive tools in future drug design.

IMPORTANCE: Therapies that improve survival in critically ill patients with coronavirus disease 2019 (COVID-19) are needed. Tocilizumab, a monoclonal antibody against the interleukin 6 receptor, may counteract the inflammatory cytokine release syndrome in patients with severe COVID-19 illness. OBJECTIVE: To test whether tocilizumab decreases mortality in this population. DESIGN, SETTING, AND PARTICIPANTS: The data for this study were derived from a multicenter cohort study of 4485 adults with COVID-19 admitted to participating intensive care units (ICUs) at 68 hospitals across the US from March 4 to May 10, 2020. Critically ill adults with COVID-19 were categorized according to whether they received or did not receive tocilizumab in the first 2 days of admission to the ICU. Data were collected retrospectively until June 12, 2020. A Cox regression model with inverse probability weighting was used to adjust for confounding. EXPOSURES: Treatment with tocilizumab in the first 2 days of ICU admission. MAIN OUTCOMES AND MEASURES: Time to death, compared via hazard ratios (HRs), and 30-day mortality, compared via risk differences. RESULTS: Among the 3924 patients included in the analysis (2464 male [62.8%]; median age, 62 [interquartile range {IQR}, 52-71] years), 433 (11.0%) received tocilizumab in the first 2 days of ICU admission. Patients treated with tocilizumab were younger (median age, 58 [IQR, 48-65] vs 63 [IQR, 52-72] years) and had a higher prevalence of hypoxemia on ICU admission (205 of 433 [47.3%] vs 1322 of 3491 [37.9%] with mechanical ventilation and a ratio of partial pressure of arterial oxygen to fraction of inspired oxygen of

Water is an essential in many biological processes, and the hydration structure plays a critical role in facilitating protein folding, dynamics and ligand binding. A variety of biophysical spectroscopic techniques have been used to probe the water solvating proteins, often complemented with molecular dynamics (MD) simulations to resolve the spatial and dynamic features of the hydration shell, but comparing relative water structure is challenging. In this study 1 microsecond MD simulations were performed to identify and characterize hydration sites around HIV-1 protease bound to an inhibitor, darunavir (DRV). The water density, hydration site occupancy, extent and anisotropy of fluctuations, coordinated water molecules, and hydrogen bonds were characterized and compared to the properties of bulk water. The water density of the principal hydration shell was found to be higher than bulk, dependent on the topology and physio-chemical identity of the biomolecular surface. The dynamics of water molecules occupying principal hydration sites was highly dependent on the number of water-water interactions, and inversely correlated with hydrogen bonds to the protein–inhibitor complex. While many waters were conserved following the symmetry of homodimeric HIV protease, the asymmetry induced by DRV resulted in asymmetric lower-occupancy hydration sites at the concave surface of the active site. Key interactions between water molecules and the protease, that stabilize the protein in the inhibited form, were altered in a drug resistant variant of the protease indicating that modulation of solvent–solute interactions might play a key role in conveying drug resistance. Our analysis provides insights into the interplay between an enzyme inhibitor complex and the hydration shell and has implications in elucidating water structure in a variety of biological processes and applications including ligand binding, inhibitor design and resistance.

Protease inhibitors have the highest potency among antiviral therapies against HIV-1 infections, yet the virus can evolve resistance. Darunavir (DRV), currently the most potent Food and Drug Administration-approved protease inhibitor, retains potency against single-site mutations. However, complex combinations of mutations can confer resistance to DRV. While the interdependence between mutations within HIV-1 protease is key for inhibitor potency, the molecular mechanisms that underlie this control remain largely unknown. In this study, we investigated the interdependence between the L89V and L90M mutations and their effects on DRV binding. These two mutations have been reported to be positively correlated with one another in HIV-1 patient-derived protease isolates, with the presence of one mutation making the probability of the occurrence of the second mutation more likely. The focus of our investigation is a patient-derived isolate, with 24 mutations that we call "KY"; this variant includes the L89V and L90M mutations. Three additional KY variants with back-mutations, KY(V89L), KY(M90L), and the KY(V89L/M90L) double mutation, were used to experimentally assess the individual and combined effects of these mutations on DRV inhibition and substrate processing. The enzymatic assays revealed that the KY(V89L) variant, with methionine at residue 90, is highly resistant, but its catalytic function is compromised. When a leucine to valine mutation at residue 89 is present simultaneously with the L90M mutation, a rescue of catalytic efficiency is observed. Molecular dynamics simulations of these DRV-bound protease variants reveal how the L90M mutation induces structural changes throughout the enzyme that undermine the binding interactions.

Here, amorphous silica nanoparticles (NPs), one of the most abundant nanomaterials, are used as an example to illustrate the utmost importance of surface coverage by functional groups which critically determines biocompatibility. Silica NPs are functionalized with increasing amounts of amino groups, and the number of surface exposed groups is quantified and characterized by detailed NMR and fluorescamine binding studies. Subsequent biocompatibility studies in the absence of serum demonstrate that, irrespective of surface modification, both plain and amine-modified silica NPs trigger cell death in RAW 264.7 macrophages. The in vitro results can be confirmed in vivo and are predictive for the inflammatory potential in murine lungs. In the presence of serum proteins, on the other hand, a replacement of only 10% of surface-active silanol groups by amines is sufficient to suppress cytotoxicity, emphasizing the relevance of exposure conditions. Mechanistic investigations identify a key role of lysosomal injury for cytotoxicity only in the presence, but not in the absence, of serum proteins. In conclusion, this work shows the critical need to rigorously characterize the surface coverage of NPs by their constituent functional groups, as well as the impact of serum, to reliably establish quantitative nanostructure activity relationships and develop safe nanomaterials.

TPS6085 Background: Differentiated thyroid cancer is the most common endocrine malignancy and has a high frequency of actionable molecular aberrations including BRAF V600E mutations (45%), RET fusions (10%), and NTRK fusions ( < 2%). FDA approved systemic therapies for metastatic radioiodine refractory differentiated thyroid cancer (RR-DTC) include multikinase inhibitors (Lenvatinib and sorafenib), NTRK inhibitors (larotrectinib and entrectinib for NTRK fusion+ cancers), and RET inhibitors (selpercatinib and pralsetinib for RET fusion+ cancers). Previous phase II clinical trials showed clinical efficacy with first and second generation BRAF inhibitors in patients with BRAF mutant RR-DTC. BRAF inhibitors have not yet been FDA approved for treatment of BRAF mutant RR-DTC. Effective therapeutic options for patients with BRAF mutant RR-DTC remains an important unmet clinical need. BRAF mutant thyroid cancers often show elevated expression of PD-L1. Additionally, BRAF inhibition results in increased expression of PD-L1 in thyroid cancer. This clinical trial seeks to evaluate the safety and efficacy of encorafenib plus binimetinib with or without nivolumab in patients with BRAF mutant metastatic RR-DTC. Encorafenib and binimetinib are highly selective and potent oral inhibitors of BRAF and MEK, respectively. Nivolumab is a potent inhibitor of the immune co-inhibitory receptor programmed cell death protein 1 (PD-1). Methods: This is a phase II, single institution, open-label, randomized clinical trial evaluating the combinations of (Arm 1) encorafenib 450 mg/day + binimetinib 45 mg twice daily and (Arm 2) encorafenib 450 mg/day + binimetinib 45 mg twice daily + nivolumab 480 mg I.V. every 4 weeks in patients with metastatic BRAF mutant RR-DTC. The trial will enroll 20 patients in each arm and treatment will be given in 28 day cycles for up to 2 years. Eligible patients must have metastatic/unresectable BRAF mutant RR-DTC, an ECOG performance status of 0-1 and adequate bone marrow, liver and kidney function. Patients with CNS metastases are included if the metastases have been treated and remained stable or are asymptomatic and ≤10 mm in diameter. Patients may be systemic therapy naïve or have previously been treated with multikinase inhibitors. Prior therapy with BRAF, MEK or immune checkpoint inhibitors is exclusionary. The primary endpoint is confirmed objective response rate (ORR) determined by RECIST v1.1 with restaging imaging every 12 weeks. Secondary endpoints include progression free survival, overall survival, and safety/tolerability (CTCAE v5.0). Arms 1 and 2 will be evaluated independently and are not powered for direct comparison. The trial design includes continuous toxicity monitoring with a Pocock-type stopping boundary. This clinical trial is in progress and 3 patients have been enrolled. Clinical trial information: NCT04061980.

To compare a low-tube-voltage with or without high-iodine-load multidetector CT (MDCT) protocol with a normal-tube-voltage, normal-iodine-load (standard) protocol in patients with pancreatic ductal adenocarcinoma (PDAC) with respect to tumour conspicuity and image quality. Thirty consecutive patients (mean age: 66 years, men/women: 14/16) preoperatively underwent triple-phase 64-channel MDCT examinations twice according to: (i) 120-kV standard protocol (PS; 0.75 g iodine (I)/kg body weight, n = 30) and (ii) 80-kV protocol A (PA; 0.75 g I/kg, n = 14) or protocol B (PB; 1 g I/kg, n = 16). Two independent readers evaluated tumour delineation and image quality blindly for all protocols. A third reader estimated the pancreas-to-tumour contrast-to-noise ratio (CNR). Statistical analysis was performed with the Chi-square test. Tumour delineation was significantly better in PB and PA compared with PS (P = 0.02). The evaluation of image quality was similar for the three protocols (all, P > 0.05). The highest CNR was observed with PB and was significantly better compared to PA (P = 0.02) and PS (P = 0.0002). In patients with PDAC, a low-tube-voltage, high-iodine-load protocol improves tumour delineation and CNR leading to higher tumour conspicuity compared to standard protocol MDCT. • Low-tube-voltage high-iodine-load MDCT improves pancreatic cancer conspicuity compared to a standard protocol. • The pancreas-to-tumour attenuation difference increases significantly by reducing the tube voltage. • The radiation exposure dose decreases by reducing the tube voltage.

HIV-1 protease is one of the prime targets of agents used in antiretroviral therapy against HIV. However, under selective pressure of protease inhibitors, primary mutations at the active site weaken inhibitor binding to confer resistance. Darunavir (DRV) is the most potent HIV-1 protease inhibitor in clinic; resistance is limited, as DRV fits well within the substrate envelope. Nevertheless, resistance is observed due to hydrophobic changes at residues including I50, V82 and I84 that line the S1/S1’ pocket within the active site. Through enzyme inhibition assays and a series of 12 crystal structures, we interrogated susceptibility of DRV and two potent analogs to primary S1’ mutations. The analogs had modifications at the hydrophobic P1’ moiety to better occupy the unexploited space in the S1’ pocket where the primary mutations were located. Considerable losses of potency were observed against protease variants with I84V and I50V mutations for all three inhibitors. The crystal structures revealed an unexpected conformational change in the flap region of I50V protease bound to the analog with the largest P1’ moiety, indicating interdependency between the S1’ subsite and the flap region. Collective analysis of protease-inhibitor van der Waals (vdW) interactions in the crystal structures using principle component analysis indicated I84V mutation underlying the largest variation in the vdW contacts. Interestingly, the principle components were able to distinguish inhibitor identity and relative potency solely based on vdW interactions of active site residues in the crystal structures. Our results reveal the interplay between inhibitor P1’ moiety and primary S1’ mutations, as well as suggesting a novel method for distinguishing the interdependence of resistance through principle component analyses.

APOBEC3s proteins (A3s), a family of human cytidine deaminases, protect the host cell from endogenous retro-elements and exogenous viral infections by introducing hypermutations. However, the ability to mutate genomic DNA makes A3s a potential cancer source. Of the 7 human A3s, A3B has been implicated as an endogenous cause for multiple cancers. Despite overall similarity, A3s have distinct deamination activity with A3B among the least catalytically active. Over the past few years, several structures of apo as well as DNA-bound A3 proteins have been determined. These structures revealed the molecular determinants of nucleotide specificity and the importance of the loops around the active site in DNA binding. However, for A3B, the structural basis for regulation of deamination activity and the role of active site loops in coordinating DNA had remained unknown. In this study, using a combination of advanced molecular modelling followed by experimental mutational analysis and dynamics simulations, we investigated molecular mechanism of A3B regulating activity and DNA binding. We identified a unique auto-inhibited conformation of A3B that restricts access and binding of DNA to the active site, mainly due to the extra PLV residues in loop 1. We modelled DNA binding to fully native A3B and found that Arg211 in the arginine patch of loop1 is the gatekeeper while Arg212 stabilizes the bound DNA. This model also identified the critical residues for substrate specificity, especially at the -1 position. Our results reveal the structural basis for relatively lower catalytic activity of A3B and provide opportunities for rational design of inhibitors that specifically target A3B to benefit cancer therapeutics.

Background To evaluate the function of arteriovenous (AV) dialysis fistula using dynamic computed tomography (CT) and time-resolved 3-dimensional (3D) volume rendering (VR). Methods Seven patients referred for angiographic CT examination of the AV dialysis fistula were enrolled. Twenty-four grams of iodine were administered intravenously (iomeprol 400 mg I/mL at 6 mL/sec) followed by a 50-mL saline flush. Dynamic scanning was performed for 15–24 sec. CT images were then postprocessed on a dedicated workstation creating time-resolved 3D VR images and movies. Results All studies showed good image quality showing pathology in 6 of 7 patients. Unexpected findings were observed in 1 patient, aneurysm ( n = 1). Radiation dose was 5 mSv. Conclusions The function of AV dialysis fistula can be visualized using dynamic CT and time-resolved 3D VR.

Molecular recognition is a highly interdependent process. Subsite couplings within the active site of proteases are most often revealed through conditional amino acid preferences in substrate recognition. However, the potential effect of these couplings on inhibition and thus inhibitor design is largely unexplored. The present study examines the interdependency of subsites in HIV-1 protease using a focused library of protease inhibitors, to aid in future inhibitor design. Previously a series of darunavir (DRV) analogs was designed to systematically probe the S1′ and S2′ subsites. Co-crystal structures of these analogs with HIV-1 protease provide the ideal opportunity to probe subsite interdependency. All-atom molecular dynamics simulations starting from these structures were performed and systematically analyzed in terms of atomic fluctuations, intermolecular interactions, and water structure. These analyses reveal that the S1′ subsite highly influences other subsites: the extension of the hydrophobic P1′ moiety results in 1) reduced van der Waals contacts in the P2′ subsite, 2) more variability in the hydrogen bond frequencies with catalytic residues and the flap water, and 3) changes in the occupancy of conserved water sites both proximal and distal to the active site. In addition, one of the monomers in this homodimeric enzyme has atomic fluctuations more highly correlated with DRV than the other monomer. These relationships intricately link the HIV-1 protease subsites and are critical to understanding molecular recognition and inhibitor binding. More broadly, the interdependency of subsite recognition within an active site requires consideration in the selection of chemical moieties in drug design; this strategy is in contrast to what is traditionally done with independent optimization of chemical moieties of an inhibitor.

The NF-κB subunit RelB is known to act either as an activator or repressor of NF-κB-dependent gene expression. The RelB-p52 heterodimer, for instance, is the key element of the alternative NF-κB signaling pathway supporting the expression of a subset of NF-κB target genes. By contrast, RelB is crucial for the repression of important pro-inflammatory cytokines like TNFα or interleukin 1β. Despite accumulating reports describing the functional variability of RelB, the molecular mechanisms underlying these divergent functions are still unknown. One potential explanation could be a functional reprogramming of RelB by different post-translational modifications. Here, we demonstrate that SUMOylation of RelB might be one of these post-translational modifications rendering the function of the NF-κB transcription factor RelB. In vivo SUMOylation analyses using either the UBC9-fusion-directed SUMOylation method or endogenous proteins from Namalwa B cells revealed that RelB is modified by either SUMO1 or SUMO2 attachment at various sites. Functional studies suggest that SUMOylation converts RelB into a transcriptional repressor. For instance, a SUMO1-RelB fusion protein mimicking RelB-SUMOylation displayed a reduced transcriptional activity in comparison to wild type RelB. Consistently, inactivation of specific SUMOylation sites in the central part of RelB augmented the transcription activity of the corresponding RelB mutant. Taken together, our data suggest that SUMOylation might be a potential molecular mechanism involved in reprogramming RelB, thus contributing to its functional diversity.

This review is focused on methods for detecting small molecules and, in particular, the characterisation of their interaction with natural proteins (e.g. receptors, ion channels). Because there are intrinsic advantages to using label-free methods over labelled methods (e.g. fluorescence, radioactivity), this review only covers label-free techniques. We briefly discuss available techniques and their advantages and disadvantages, especially as related to investigating the interaction between small molecules and proteins. The reviewed techniques include well-known and widely used standard analytical methods (e.g. HPLC-MS, NMR, calorimetry, and X-ray diffraction), newer and more specialised analytical methods (e.g. biosensors), biological systems (e.g. cell lines and animal models), and in-silico approaches.

A grating coupler system has been developed to measure refractive index gradients with high spatial (6.7 μm) and temporal (milliseconds) resolution. The system was applied to two-phase model systems consisting of water and non-aqueous pollution liquids. Refractive index gradients at the interfaces between the aqueous and organic phase of 1-butanol, hexane, and 1-heptanol were monitored under steady-state conditions. The temporal resolution was utilized in diffusion experiments with glycerol and sodium chloride in water, where the formation of a concentration gradient was studied. In a further application, the grating coupler system was modified to monitor low-level concentrations of aqueous pollution profiles as are caused by bacterial degradation in the aqueous phase. Toluene was selected as contaminant. The sensor sensitivity was improved by coating the sensor with the pre-concentrating polymers polydimethylsiloxane and Teflon(®) AF-2400. With the grating coupler setup, a multi-purpose instrument was created to measure high-resolution refractive index gradients with high temporal and spatial resolution in different fields of application. The new sensor system can be used to measure absolute refractive indices by covering parts of the sensing area with cover media of known refractive index. Coatings can be used for sensitivity improvement by pre-concentrating the sample, for selectivity by utilizing filtering properties of the coating, and as calibration standard for absolute refractive index measurements.

Despite significant progress in hepatitis C virus (HCV) protease inhibitor (PI) drug design, resistance remains a problem causing treatment failure. Double-substitution variants, notably Y56H/D168A, have emerged in patients who fail therapy with a PI-containing regimen. The resistance conferred by Asp168 substitutions has been well characterized and avoided in newer inhibitors. However, an additional mutation at Tyr56 confers resistance to even the most robust inhibitors. Here, we elucidate the molecular mechanisms of resistance for the Y56H/D168A variant against grazoprevir (and four analogs), paritaprevir, and danoprevir through inhibition assays, co-crystal structures, and molecular dynamics simulations. The PIs' susceptibility to Y56H/D168A varies, with those stacking on the catalytic His57 losing the most potency. For such inhibitors, the Y56H substitution disrupts favorable stacking interactions with the neighboring catalytic His57. This indirect mechanism of resistance threatens to cause multi-PI failure as all HCV PIs in clinical development rely on interactions with the catalytic triad.

The IkappaB-Kinase (IKK) complex is a multisubunit protein complex crucial for signal-induced phosphorylation of the IkappaB proteins and thus controls the activity of the transcription factor NF-kappaB. Besides the two kinases IKKalpha and IKKbeta, the IKK complex contains NEMO/IKKgamma, an additional subunit with regulatory and adaptor functions. NEMO not only confers structural stability to the IKK complex but also participates in the activation process of the IKK complex by linking the IKK subunits to upstream activators. In this study we analyze the IKKbeta-mediated phosphorylation of the IKK-binding domain of NEMO. In vitro, IKKbeta phosphorylates three serine residues in the domain of NEMO at positions 43, 68, and 85. However, mutational analysis revealed that only the phosphorylation of serine 68 in the center of the IKK-binding domain plays an essential role for the formation and the function of the IKK complex. Thus, Ser(68) phosphorylation attenuates the amino-terminal dimerization of NEMO as well as the IKKbeta-NEMO interaction. In contrast, the NEMO-IKKalpha interaction was only mildly affected by the phosphorylation of Ser(68). However, functional analysis revealed that Ser(68) phosphorylation primarily affects the activity of IKKalpha. Furthermore, in complementation experiments of NEMO-deficient murine embryonic fibroblasts, a S68A-NEMO mutant enhanced, whereas a S68E mutant decreased, TNF-alpha-induced NF-kappaB activity, thus emphasizing the inhibitory role of the Ser(68) phosphorylation on the signal-induced NF-kappaB activity. Finally, we provide evidence that the protein phosphatase PP2A is involved in the regulation of the Ser(68)-based mechanism. In summary, we provide evidence for a signal-induced phosphorylation-dependent alteration of the IKK complex emphasizing the dynamic nature of this multisubunit kinase complex.

Introduction Despite declining risk of vertical HIV transmission, prophylactic cotrimoxazole (CTX) remains widely used to reduce morbidity and mortality in the event of HIV infection among exposed infants, with an inherent risk of conferring commensal antimicrobial resistance. Using data from a randomized, placebo-controlled trial of infant CTX prophylaxis, we sought to quantify emergence of antibiotic resistance. Methods HIV-exposed uninfected infants enrolled in the Botswana Mpepu study were randomized to prophylactic CTX or placebo between 14 and 34 days of life and continued through 15 months. Stool samples were collected from a subset of participating infants at randomization, three, and six months, and stored at −70°C prior to culture. Specimens that grew Escherichia coli (E. coli) or Klebsiella species (Klebsiella spp.) underwent antibiotic susceptibility testing by Kirby Bauer method using CTX (CTX 1.25/23.75 μg) and Amoxicillin (10 μg) in Mueller Hinton agar. Fisher's exact testing was used to compare prevalence of resistance by randomization arm (CTX/placebo). Results and Discussion A total of 381 stool samples from 220 infants were cultured: 118 at randomization, 151 at three months, and 112 at six-months. E. coli was isolated from 206 specimens and Klebsiella spp. from 138 specimens. Resistance to CTX was common in both E. coli and Klebsiella spp. at the randomization visit (52.2% and 37.7% respectively) and did not differ by study arm. E. Coli isolates from CTX recipients at three and six months had 94.9% and 84.2% CTX resistance, as compared with 51.4% and 57.5% CTX resistance in isolates from placebo recipients (p=0.01). Klebsiella spp. isolates from CTX recipients had 79.0% and 68.8% CTX resistance at three and six months, as compared with 19.1% and 14.3% in isolates from placebo recipients (p

Gastrin-releasing-peptide (GRP)-receptors and αvβ3-integrins are widely discussed as potential target structures for oncological imaging with positron emission tomography (PET). Favored by the overexpression of receptors on the surface of tumor cells good imaging characteristics can be achieved with highly specific radiolabeled receptor ligands. PEGylated bombesin (PESIN) derivatives as specific GRP receptor ligands and RGD (one-letter codes for arginine-glycine-aspartic acid) peptides as specific αvβ3 binders were synthesized and tagged with a silicon-fluorine-acceptor (SiFA) moiety. The SiFA synthon allows for a fast and highly efficient isotopic exchange reaction at room temperature giving the [(18)F]fluoride labeled peptides in up to 62% radiochemical yields (d.c.) and ≥99% radiochemical purity in a total synthesis time of less than 20 min. Using nanomolar quantities of precursor high specific activities of up to 60 GBq μmol(-1) were obtained. To compensate the high lipophilicity of the SiFA moiety various hydrophilic structure modifications were introduced leading to significantly reduced logD values. Competitive displacement experiments with the PESIN derivatives showed a 32 to 6 nM affinity to the GRP receptor on PC3 cells, and with the RGD peptides a 7 to 3 μM affinity to the αvβ3 integrins on U87MG cells. All derivatives proved to be stable in human plasma over at least 120 min. Small animal PET measurements and biodistribution studies revealed an enhanced and specific accumulation of the RGD peptide (18)F-SiFA-LysMe3-γ-carboxy-d-Glu-RGD (17) in the tumor tissue of U87MG tumor-bearing mice of 5.3% ID/g whereas the PESIN derivatives showed a high liver uptake and only a low accumulation in the tumor tissue of PC3 xenografts. Stability studies with compound 17 provided further information on its metabolism in vivo. These results altogether demonstrate that the reduction of the overall lipophilicity of SiFA tagged RGD peptides is a promising approach for the generation of novel potent (18)F-labeled imaging agents.

We report the design, fabrication, and first functional verification of mid-infrared (MIR; 3–12 μm) Mach–Zehnder interferometers (MZIs). The developed MIR-MZIs are entirely chip-integrated solid-state devices based on GaAs/AlGaAs technology waveguide fabricated via conventional optical lithography and reactive ion etching (RIE). Thus, fabricated MIR-MZIs were combined with a broadly tunable quantum cascade laser (tQCL) providing a wavelength coverage of 5.78–6.35 μm. MIR-MZIs have been designed with a waveguide width of 5 μm to ensure single mode behavior, avoiding optically undefined interference patterns. Several structures with different opening angles of the Y-junction were fabricated and tested for maximizing IR radiation throughput. This study demonstrates the feasibility of the very first chip-integrated mid-infrared Mach–Zehnder structures via interference patterns produced by minute amounts of water deposited at different positions of the MIR-MZI structure.

Cyclic voltammetry has been employed to study the reactivity of Ru(OEP)(p-XC 6 H 4 ) 2 (OEP=octaethylporphyrin dianion; X=H, CH 3 , OCH 3 , Cl, F) complexes in extreme oxidation states. As previously demonstrated for Ru(OEP)(C 6 H 5 ) 5 , the [Ru(OEP)(aryl) 2 ] + complexes undergo Ru-to-N migration of an aryl group, while the [Ru(OEP)(aryl) 2 ] 2- complexes lose aryl - to form [Ru(OEP)(aryl)] - .

Polarization modulation Fourier transform infrared reflectance (PM-FTIR) spectroscopy has been employed to study the pressure-dependent molecular structure of functionalized phospholipid monolayers at the gold-air interface. Head-down monolayers of dipalmitoylphosphatidylcholine (DPPC) and the anthraquinone- and anthracene-functionalized analogues (DPPC-AQ and DPPC-AN) have been prepared on vapor-deposited polycristalline gold surfaces using Langmuir-Blodgett techniques.

Quinone-functionalized liposomes can be prepared by the sonic dispersion of a phosphatidylcholine anthraquinone (DPPC-AQ) with simple phospholipids such as DPPC (at 52°C) and DOPC (at room temperature). These small (ca. 25-30-nm diameter), unilamellar liposomes typically contain 4-12 mol % phospholipid quinone, which can be reduced and reoxidized by solution reagents

RelB is the key component of the alternative NF-kappaB (nuclear factor kappaB) signalling pathway. However, RelB exerts also a negative effect via the recruitment of a DNMT1 (DNA methyltransferase 1)-Daxx (death domain-associated protein) complex to NF-kappaB target genes. Importantly, the molecular mechanisms which determine the functions of RelB are still largely unknown. In the present study, we aimed to analyse whether ubiquitination of RelB might be involved in the regulation of RelB. Indeed, RelB is constitutively polyubiquitinated in the B-cell lines Namalwa and 70Z/3. Although a PMA+ionomycin-induced augmentation of RelB polyubiquitination was linked to its proteasomal degradation in B-cells, the constitutive RelB polyubiquitination seems to affect non-proteasomal functions. Consistently, a significant RelB polyubiquitination in HEK (human embryonic kidney)-293 cells correlated with an augmentation of the transcriptional activity of RelB. Yet, neither nuclear localization nor DNA binding was enhanced by RelB polyubiquitination. Interestingly, basal RelB polyubiquitination depends neither on Lys(48) nor on Lys(63) conjugates, but might involve unconventional ubiquitin conjugates. Mapping of the ubiquitination target sites in RelB revealed the existence of various lysine residues, which serve as ubiquitination acceptors. However, only the substitution of Lys(273/274) and Lys(305/308) significantly decreased the basal RelB activity and the ubiquitin-induced augmentation of the RelB activity. Collectively, these results imply a dual role of RelB polyubiquitination for the stability and activity of this transcription factor.

Cyclic voltammetry of Ru(OEP)(C 6 H 5 ) 2 and Ru(OEP)(C 6 H 5 ) (OEP=octaethylporphyrin dianion) reveals diverse redox and accompanying chemical reactions. Chemical oxidations and reductions of the neutral complexes yield several isolable products, including the N-arylated [Ru(OEP-N-C 6 H 5 )(C 6 H 5 )] + complex

A novel phospholipid quinone bearing hexadecyl ether chains has been synthesized and employed in the preparation of redox-active, quinone-functionalized liposomes.

Poster: "ECR 2016 / C-2276 / Multidetector CT of pancreatic ductal adenocarcinoma: effect of tube-voltage and iodine-load on tumour conspicuity, vessel involvement and image quality " by: "L. Loizou1, N. Albiin2, B. Leidner1, E. Axelsson1, M. Fischer1, R. Segersvard1, C. Verbeke1, A. Sundin3, N. Kartalis 1; 1Huddinge/SE, 2Stockholm/SE, 3Uppsala/SE"

Electroactive polymer actuators that utilize the Maxwell stress effect have generated considerable interest in recent years for use in applications such as artificial muscles, sensors, and parasitic energy capture. In order to maximize performance, the dielectric layer in Maxwell stress actuators should ideally have a high dielectric constant and high dielectric breakdown strength. In this study, the effect of high dielectric constant fillers on the electrical and mechanical properties of thin elastomeric films was examined. The fillers studied included the inorganic compounds titanium dioxide (TiO2), barium titanate (BaTiO3), and lead magnesium niobate-lead titanate (Pb(Mg1/3Nb2/3)O3-PbTiO). A high dielectric constant filler based on a polymeric conjugated ligand-metal complex, poly(copper phthalocyanine), was also synthesized and studied. Maxwell stress actuators fabricated with BaTiO3 dispersed in a silicone elastomer matrix were evaluated and compared with unfilled systems. A model was presented which relates filler volume fraction to actuation stress, strain, and elastic energy density at fields below dielectric breakdown. The model and experimental results suggest that for the case of strong filler particle-elastomer matrix interaction, actuation strain decreases with increasing filler content.

Preface. 1. Introduction. 2. Fundamental Issues Pertinent to Polymer Recycling. 3. Reprocessing of Single Type Polymers. 4. Reprocessing of Mixture of Polymers. 5. Recovery of Chemicals and Energy. 6. The Way Forward. Index.

Composite films containing solid state laser nanoparticles have been created which show optical amplification in the technologically important near IR range. The solid state laser materials studied, Cr-forsterite (Cr-Mg{sub 2}SiO{sub 4}) and Cr-diopside (Cr-CaMgSi{sub 2}O{sub 6}), were prepared using a dispersion polymerized polymer precursor. The nanoparticles produced during the polymer synthesis acted as size templates, creating fine crystalline powders of the Cr-forsterite and Cr-diopside upon calcination. These fine powders were dispersed in a refractive index matched polymer matrix and cast as 5--10 {micro}m thick films. The resulting composite containing Cr-forsterite showed optical amplification of 300 dB/m at 1.24 {micro}m.

a—Si1−xGex:H alloy films with 0 > × > 1 have been prepared by reactive co— sputtering (rf—magnetron) from separate targets. The preparation conditions which have been optimized for each composition x must be changed from a—Si:H—like (0 > × > 0.4) to a—Ge:H—like (× < 0.7) to obtain the best photoelectrical quality of the alloy material. The preferential attachment of hydrogen was quantitatively investigated by detailed ir—spectrometric studies. Its monotonic change with x is attributed to fundamental preferential attachment of hydrogen to silicon superimposed by a further preferential attachment to the respective minority alloy partner. The preferential attachment of hydrogen essentially influences the microstructure of the film and thus the material properties.

Studies of molecular superconductivity have centered around a class of closely-related charge transfer salts. The synthesis, structural characterization, and especially the physics of this class of molecular superconductors dominate this conference.

MODEL JUDETTE LOUIS, JOHN HOTRA, JAMES JANISSE, ROBERT SOKOL, CaseMetrohealth Medical Center, Cleveland, Ohio, Wayne State University, Detroit, Michigan OBJECTIVE: We recently reported a strong association between alcohol exposure during human pregnancy and extreme preterm delivery; here, we sought to validate a previously reported murine model to facilitate mechanistic studies. STUDY DESIGN: Nulliparous 10-12 week old female C57BL/6J mice were randomized to one of 20 treatment groups and bred using a timed breeding method. Each mouse received one of four doses of alcohol (0, 4, 5 or 6 grams of alcohol/kg body weight) on one of five gestational days (GD) (GD 10, 15, 16, 17, 18). Cages were monitored every 6h for deliveries. Data were analyzed utilizing a 4x5 ANOVA. RESULTS: The alcohol dose by day of exposure interaction was significant (p 0.015), while the main effects for alcohol dose (p 0.942), and day of exposure (p 0.157) on gestational length were not. Examination of the interaction revealed a differential effect of day of exposure on the control group, compared to the alcohol exposed groups. Among the control group mice receiving no alcohol, the GD 10 group had a significantly longer gestation (mean 20.5) than the GD15 (mean 19.2), 17 (mean 19.4) and 18 (mean 19.3) groups. However, the day of exposure was not related to length of gestation in the alcohol groups (p 0.157). Average length of gestation for the alcohol groups was 19.3 days. CONCLUSION: Failing to confirm a previous study in this murine prenatal alcohol exposure model, no relation to gestational duration was detected. An effect may have been cloaked by an apparent major effect of intubation. Again attempting to confirm this model with additional controls or another dosing method or finding other animal models would facilitate further study of prenatal alcohol exposure and preterm delivery risk.

Amphiphiles from quinone-functionalized liposome solutions spontaneously adsorb onto glassy carbon electrodes to form electroactive, monolayer deposits.