Peptoid Residues Make Diverse, Hyperstable Collagen Triple-Helices.

As the only ribosomally encoded N-substituted amino acid, proline promotes distinct secondary protein structures. The high proline content in collagen, the most abundant protein in the human body, is crucial to forming its hallmark structure: the triple-helix. For over five decades, proline has been considered compulsory for synthetic designs aimed at recapitulating collagen's structure and properties. Here we describe that N-substituted glycines (N-glys), also known as peptoid residues, exhibit a general triple-helical propensity similar to or greater than proline, enabling synthesis of stable triple-helical collagen mimetic peptides (CMPs) with unprecedented side chain diversity. Supported by atomic-resolution crystal structures as well as circular dichroism and computational characterizations spanning over 30 N-gly-containing CMPs, we discovered that N-glys stabilize the triple-helix primarily by sterically preorganizing individual chains into the polyproline-II helix. We demonstrated that N-glys with exotic side chains including a "click"-able alkyne and a photosensitive side chain enable CMPs for functional applications including the spatiotemporal control of cell adhesion and migration. The structural principles uncovered in this study open up opportunities for a new generation of collagen-mimetic therapeutics and materials.

MERTK Mediates Intrinsic and Adaptive Resistance to AXL-targeting Agents.

The TAM (TYRO3, AXL, MERTK) family receptor tyrosine kinases (RTK) play an important role in promoting growth, survival, and metastatic spread of several tumor types. AXL and MERTK are overexpressed in head and neck squamous cell carcinoma (HNSCC), triple-negative breast cancer (TNBC), and non-small cell lung cancer (NSCLC), malignancies that are highly metastatic and lethal. AXL is the most well-characterized TAM receptor and mediates resistance to both conventional and targeted cancer therapies. AXL is highly expressed in aggressive tumor types, and patients with cancer are currently being enrolled in clinical trials testing AXL inhibitors. In this study, we analyzed the effects of AXL inhibition using a small-molecule AXL inhibitor, a monoclonal antibody (mAb), and siRNA in HNSCC, TNBC, and NSCLC preclinical models. Anti-AXL-targeting strategies had limited efficacy across these different models that, our data suggest, could be attributed to upregulation of MERTK. MERTK expression was increased in cell lines and patient-derived xenografts treated with AXL inhibitors and inhibition of MERTK sensitized HNSCC, TNBC, and NSCLC preclinical models to AXL inhibition. Dual targeting of AXL and MERTK led to a more potent blockade of downstream signaling, synergistic inhibition of tumor cell expansion in culture, and reduced tumor growth in vivo Furthermore, ectopic overexpression of MERTK in AXL inhibitor-sensitive models resulted in resistance to AXL-targeting strategies. These observations suggest that therapeutic strategies cotargeting both AXL and MERTK could be highly beneficial in a variety of tumor types where both receptors are expressed, leading to improved survival for patients with lethal malignancies. Mol Cancer Ther; 17(11); 2297-308. ©2018 AACR.

Improved diagnostic clarity in shrimp allergic non-dust-mite sensitized patients.

BACKGROUND: Allergen specific immunoglobulin E (sIgE) levels predictive of shrimp allergy have not been identified, but these may be helpful in identifying patients at risk for shrimp-induced allergic reactions. OBJECTIVE: This study sought to identify component resolved diagnostic tests useful for diagnosis of shrimp allergy in patients with or without house-dust mite (HDM) sensitization to the major allergen cysteine protease (Der p 1). METHODS: Patients with positive skin-prick test (SPT) results and/or sIgE values were recruited. Shrimp allergy was classified by oral food challenge (OFC) or by a clear history of anaphylaxis after shrimp ingestion. Patients with shrimp allergy and patients who were tolerant were further classified based on HDM sensitivity (Der p 1 > 0.35 kUA/L). Testing for sIgE to total shrimp, and shrimp and HDM components was performed. The Fisher exact test, Wilcoxon sum rank test, and receiver operating characteristics analyses were used to compare sIgE levels in patients with allergy and patients who were tolerant. RESULTS: Of 79 patients recruited, 12 patients with shrimp allergy (7 with positive OFC results and 5 with a history of anaphylaxis) and 18 patients who were shrimp tolerant were enrolled. Of the patients not HDM sensitized, sIgE levels to shrimp (10.5 kUA/L, p = 0.012) and Der p 10 (4.09 kUA/L, p = 0.035) were higher in patients with shrimp allergy. Shrimp sIgE of ≥3.55 kUA/L had 100% diagnostic sensitivity and 85.7% specificity (receiver operating characteristic 0.94 [0.81, 1.0] 95% CI) and Der p 10 sIgE levels of ≥3.98 kUA/L had a diagnostic sensitivity of 80% and specificity of 100% (receiver operating characteristic 0.86 [0.57, 1.0] 95% CI) for prediction of clinical reactivity. CONCLUSION: HDM sensitization influences shrimp and HDM component sIgE levels and, consequently, their diagnostic accuracy in shrimp allergy. In our series, in the patients who were non-HDM sensitized, a shrimp sIgE level of >3.55 kUA/L showed 100% sensitivity and, Der p 10 sIgE of >3.98 kUA/L showed 100% specificity for the diagnosis of shrimp allergy. These levels may not be applicable to every patient and, therefore, may not obviate the need for OFC.

Thyroxine and triiodothyronine content in commercially available thyroid health supplements.

BACKGROUND: As defined by the Dietary Supplement Health and Education Act 1997, such substances as herbs and dietary supplements fall under general Food and Drug Administration supervision but have not been closely regulated to date. We examined the thyroid hormone content in readily available dietary health supplements marketed for "thyroid support." METHODS: Ten commercially available thyroid dietary supplements were purchased. Thyroid supplements were dissolved in 10 mL of acetonitrile and water with 0.1% trifloroacetic acid and analyzed using high-performance liquid chromatography for the presence of both thyroxine (T4) and triiodothyronine (T3) using levothyroxine and liothyronine as a positive controls and standards. RESULTS: The amount of T4 and T3 was measured separately for each supplement sample. Nine out of 10 supplements revealed a detectable amount of T3 (1.3-25.4 µg/tablet) and 5 of 10 contained T4 (5.77-22.9 µg/tablet). Taken at the recommended dose, 5 supplements delivered T3 quantities of greater than 10 µg/day, and 4 delivered T4 quantities ranging from 8.57 to 91.6 µg/day. CONCLUSIONS: The majority of dietary thyroid supplements studied contained clinically relevant amounts of T4 and T3, some of which exceeded common treatment doses for hypothyroidism. These amounts of thyroid hormone, found in easily accessible dietary supplements, potentially expose patients to the risk of alterations in thyroid levels even to the point of developing iatrogenic thyrotoxicosis. The current study results emphasize the importance of patient and provider education regarding the use of dietary supplements and highlight the need for greater regulation of these products, which hold potential danger to public health.

Well-ordered porous conductive polypyrrole as a new platform for neural interfaces.

We present the preparation of electrically conductive, porous polypyrrole surfaces and demonstrate their use as an interactive substrate for neuronal growth. Nerve growth factor (NGF)-loaded porous conducting polymers were initially prepared by electrochemical deposition of a mixture of pyrrole monomers and NGF into two- or three-dimensional particle arrays followed by subsequent removal of a sacrificial template. Morphological observation by scanning electron microscopy (SEM) revealed these to possess high regularity and porosity with well-defined topographical features. A four-point probe study demonstrated remarkable electrical activities despite the presence of voids. In addition, we investigated the effects of these surfaces on cellular behaviors using PC 12 cells in the presence and absence of electrical stimulation. Our results suggest that the surface topography as well as an applied electrical field can play a crucial role in determining further cell responses. Indeed, surface-induced preferential regulation leads to enhanced cellular viability and neurite extension. Establishing the underlying cellular mechanisms in response to various external stimuli is essential in that one can elicit positive neuronal guidance and modulate their activities by engineering a series of electrical, chemical, and topographical cues.

Analysis of the kinetics of band 3 diffusion in human erythroblasts during assembly of the erythrocyte membrane skeleton.

During definitive erythropoiesis, erythroid precursors undergo differentiation through multiple nucleated states to an enucleated reticulocyte, which loses its residual RNA/organelles to become a mature erythrocyte. Over the course of these transformations, continuous changes in membrane proteins occur, including shifts in protein abundance, rates of expression, isoform prominence, states of phosphorylation, and stability. In an effort to understand when assembly of membrane proteins into an architecture characteristic of the mature erythrocyte occurs, we quantitated the lateral diffusion of the most abundant membrane protein, band 3 (AE1), during each stage of erythropoiesis using single particle tracking. Analysis of the lateral trajectories of individual band 3 molecules revealed a gradual reduction in mobility of the anion transporter as erythroblasts differentiated. Evidence for this progressive immobilization included a gradual decline in diffusion coefficients as determined at a video acquisition rate of 120 frames/s and a decrease in the percentage of compartment sizes >100 nm. Because complete acquisition of the properties of band 3 seen in mature erythrocytes is not observed until circulating erythrocytes are formed, we suggest that membrane maturation involves a gradual and cooperative assembly process that is not triggered by the synthesis of any single protein.

Mortality associated with Acinetobacter baumannii complex bacteremia among patients with war-related trauma.

We investigated the mortality associated with Acinetobacter baumannii complex bacteremia among a cohort of patients hospitalized for war-related trauma. Despite a high prevalence of multidrug-resistant strains, the 30-day mortality rate was 2%. For relatively young patients with war-related trauma, A. baumannii complex bacteremia appears to be associated with a low risk of death.

Intercellular transfer of P-glycoprotein mediates acquired multidrug resistance in tumor cells.

The overexpression of P-glycoprotein (P-gp) causes resistance to chemotherapy in many tumor types. Here, we report intercellular transfer of functional P-gp from P-gp-positive to P-gp-negative cells in vitro and in vivo. The expression of acquired P-gp is transient in isolated cells but persists in the presence of P-gp-positive cells or under the selective pressure of colchicine. The intercellular transfer of functional P-gp occurs between different tumor cell types and results in increased drug resistance both in vitro and in vivo. Most importantly, the acquired resistance permits tumor cells to survive potentially toxic drug concentrations long enough to develop intrinsic P-gp-mediated resistance. P-gp transfer also occurs to putative components of tumor stroma, such as fibroblasts, raising the possibility that multidrug resistance could be conferred by resistant tumor cells to critical stromal elements within the tumor mass. This is the first report, to our knowledge, that a protein transferred between cells retains its function and confers a complex biologic property upon the recipient cell. These findings have important implications for proteomic analyses in tumor samples and resistance to cancer therapy.