X-ray Raman scattering for bulk chemical and structural insight into green carbon.

X-ray Raman scattering (XRS) spectroscopy is an emerging inelastic scattering technique which uses hard X-rays to study the X-ray absorption edges of low-Z elements (e.g. C, N, O) in bulk. This study applies XRS spectroscopy to pyrolysis and hydrothermal carbons. These materials are thermochemically-produced carbon from renewable resources and represent a route for the sustainable production of carbon materials for many applications. Results confirm local structural differences between biomass-derived (Oak, Quercus Ilex) pyrolysis and hydrothermal carbon. In comparison with NEXAFS, XRS spectroscopy has been shown to be more resilient to experimental artefacts such as self-absorption. Density functional theory XRS calculations of potential structural sub-units confirm that hydrothermal carbon is a highly disordered carbon material formed principally of furan units linked by the α carbon atoms. Comparison of two pyrolysis temperatures (450 °C and 650 °C) shows the development of an increasingly condensed carbon structure. Based on our results, we have proposed a semi-quantitative route to pyrolysis condensation.

Polymeric nanoparticles as cancer-specific DNA delivery vectors to human hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the third most deadly cancer in the US, with a meager 5-year survival rate of <20%. Such unfavorable numbers are closely related to the heterogeneity of the disease and the unsatisfactory therapies currently used to manage patients with invasive HCC. Outside of the clinic, gene therapy research is evolving to overcome the poor responses and toxicity associated with standard treatments. The inadequacy of gene delivery vectors, including poor intracellular delivery and cell specificity, are major barriers in the gene therapy field. Herein, we described a non-viral strategy for effective and cancer-specific DNA delivery to human HCC using biodegradable poly(beta-amino ester) (PBAE) nanoparticles (NPs). Varied PBAE NP formulations were evaluated for transfection efficacy and cytotoxicity to a range of human HCC cells as well as healthy human hepatocytes. To address HCC heterogeneity, nine different sources of human HCC cells were utilized. The polymeric NPs composed of 2-((3-aminopropyl)amino) ethanol end-modified poly(1,5-pentanediol diacrylate-co-3-amino-1-propanol) ('536') at a 25 polymer-to-DNA weight-to-weight ratio led to high transfection efficacy to all of the liver cancer lines, but not to hepatocytes. Each individual HCC line had a significantly higher percentage of exogenous gene expression than the healthy liver cells (P<0.01). Notably, this biodegradable end-modified PBAE gene delivery vector was not cytotoxic and maintained the viability of hepatocytes above 80%. In a HCC/hepatocyte co-culture model, in which cancerous and healthy cells share the same micro-environment, 536 25 w/w NPs specifically transfected cancer cells. PBAE NP administration to a subcutaneous HCC mouse model, established with one of the human lines tested in vitro, confirmed effective DNA transfection in vivo. PBAE-based NPs enabled high and preferential DNA delivery to HCC cells, sparing healthy hepatocytes. These biodegradable and liver cancer-selective NPs are a promising technology to deliver therapeutic genes to liver cancer.

Ag colloids and arrays for plasmonic non-radiative energy transfer from quantum dots to a quantum well.

Non-radiative energy transfer (NRET) can be an efficient process of benefit to many applications including photovoltaics, sensors, light emitting diodes and photodetectors. Combining the remarkable optical properties of quantum dots (QDs) with the electrical properties of quantum wells (QWs) allows for the formation of hybrid devices which can utilize NRET as a means of transferring absorbed optical energy from the QDs to the QW. Here we report on plasmon-enhanced NRET from semiconductor nanocrystal QDs to a QW. Ag nanoparticles in the form of colloids and ordered arrays are used to demonstrate plasmon-mediated NRET from QDs to QWs with varying top barrier thicknesses. Plasmon-mediated energy transfer (ET) efficiencies of up to ∼25% are observed with the Ag colloids. The distance dependence of the plasmon-mediated ET is found to follow the same d -4 dependence as the direct QD to QW ET. There is also evidence for an increase in the characteristic distance of the interaction, thus indicating that it follows a Förster-like model with the Ag nanoparticle-QD acting as an enhanced donor dipole. Ordered Ag nanoparticle arrays display plasmon-mediated ET efficiencies up to ∼21%. To explore the tunability of the array system, two arrays with different geometries are presented. It is demonstrated that changing the geometry of the array allows a transition from overall quenching of the acceptor QW emission to enhancement, as well as control of the competition between the QD donor quenching and ET rates.

Influence of plasmonic array geometry on energy transfer from a quantum well to a quantum dot layer.

A range of seven different Ag plasmonic arrays formed using nanostructures of varying shape, size and gap were fabricated using helium-ion lithography (HIL) on an InGaN/GaN quantum well (QW) substrate. The influence of the array geometry on plasmon-enhanced Förster resonance energy transfer (FRET) from a single InGaN QW to a ∼80 nm layer of CdSe/ZnS quantum dots (QDs) embedded in a poly(methyl methacrylate) (PMMA) matrix is investigated. It is shown that the energy transfer efficiency is strongly dependent on the array properties and an efficiency of ∼51% is observed for a nanoring array. There were no signatures of FRET in the absence of the arrays. The QD acceptor layer emission is highly sensitive to the array geometry. A model was developed to confirm that the increase in the QD emission on the QW substrate compared with a GaN substrate can be attributed solely to plasmon-enhanced FRET. The individual contributions of direct enhancement of the QD layer emission by the array and the plasmon-enhanced FRET are separated out, with the QD emission described by the product of an array emission factor and an energy transfer factor. It is shown that while the nanoring geometry results in an energy transfer factor of ∼1.7 the competing quenching by the array, with an array emission factor of ∼0.7, results in only an overall gain of ∼14% in the QD emission. The QD emission was enhanced by ∼71% for a nanobox array, resulting from the combination of a more modest energy transfer factor of 1.2 coupled with an array emission factor of ∼1.4.

Renal Ablation Techniques: State of the Art.

OBJECTIVE: The purpose of this article is to describe the indications for and approach to image-guided percutaneous ablation of renal tumors. CONCLUSION: Image-guided ablation techniques have become accepted treatment of patients with small renal tumors, a viable alternative to partial nephrectomy.

Avoiding miscommunication in acute musculoskeletal trauma cases: use of standardized reporting and classification schemes.

Classification schemes can be a key element of a structured radiology report, providing succinct guidance for clinical decision making. Classification systems delineate the location and morphological characteristics of fractures (diagnosis), may provide a graded measure of severity (prognosis), and ideally guide treatment options. Reports structured in this fashion optimize communication between the physician interpreting the examination and the physician directing the patient's treatment. This article reviews the concept and utility of standardized structured radiologic reporting based on templates or checklists to avoid miscommunication in the context of acute musculoskeletal trauma.

Student award winner in the Ph.D. category for the 2013 society for biomaterials annual meeting and exposition, april 10-13, 2013, Boston, Massachusetts : biomaterial-mediated cancer-specific DNA delivery to liver cell cultures using synthetic poly(beta-amino ester)s.

Liver cancer is a leading cause of cancer death. Most patients are treated by arterial injection of chemoembolizing agents, providing a convenient avenue for local treatment by novel therapies, including gene therapy. Poly(beta-amino ester)s (PBAEs) were synthesized and used to form nanoparticles for non-viral transfection of buffalo rat hepatoma (MCA-RH7777) and hepatocyte (BRL-3A) lines with eGFP and luciferase DNA. Hepatoma cells were transfected with up to (98 ± 0.4)% efficacy with no measurable cytotoxicity. Hepatocytes were transfected with as high as (73 ± 0.4)% efficacy with (10 ± 4)% non-specific cytotoxicity. In contrast, positive controls (branched polyethylenimine, Lipofectamine™ 2000, and X-tremeGENE(®) DNA HP) caused 30-90% toxicity in BRL-3A cells at doses required for >50% transfection. Of the 21 optimized PBAE-DNA formulations tested, 12 showed significant specificity for hepatoma cells over hepatocytes in monoculture (p < 0.05 for both percentage transfected and eGFP expression intensity). Top polymers from eGFP studies also delivered luciferase DNA with 220 ± 30-fold and 470 ± 30-fold greater specificity for hepatoma cells than hepatocytes. Transfections of co-cultures of hepatoma and hepatocytes with eGFP DNA also showed high specificity (1.9 ± 0.1- to 5.8± 1.4-fold more transfected hepatoma cells than hepatocytes, measured by percentage transfected and flow cytometry). By eGFP intensity, up to 530 ±60-fold higher average expression per cell was measured in hepatoma cells. One top formulation caused (95 ± 0.2)% transfection in hepatoma cells and (27 ± 0.2)% in hepatocytes [(96 ± 9)% relative hepatocyte viability]. PBAE-based nanoparticles are a viable strategy for liver cancer treatment, delivering genes to nearly 100% of cancer cells while maintaining high biomaterial-mediated specificity to prevent toxic side-effects on healthy hepatocytes.

In vitro design and characterization of the nonviral gene delivery vector iopamidol, protamine, ethiodized oil reagent.

PURPOSE: To demonstrate cellular selectivity toward hepatoma cells and compare the efficiency of gene delivery of a novel nonviral vector of iopamidol, protamine, and ethiodized oil reagents (VIPER). MATERIALS AND METHODS: Rat hepatocellular carcinoma (HCC) cells were transfected in triplicate under varying conditions by using firefly luciferase as a reporter gene. Conditions included variations of a protamine:DNA (P:D) complex (20:1, 50:1, 100:1, 200:1 mass ratios), iopamidol (0%, 10%, 33%), and ethiodized oil (0%, 1%, 2%, 4%, 8%, and 16%). The conditions affording efficient gene transfer and ease of translation to in vivo studies were selected for cell line comparison (HCC cells vs hepatocytes). Adenoviral transduction was compared with nonviral vector transfection. RESULTS: At low concentrations, ethiodized oil increased transfection efficiency regardless of P:D mass ratio. However, high concentrations resulted in significant attenuation. Unexpectedly, the addition of iopamidol to P:D complexes markedly improved transfection efficiency. When using an optimal P:D, iopamidol, and ethiodized oil solution, DNA transfection of normal liver and tumor cells showed significant selectivity for tumor cells. In the context of hepatoma cells, transfection efficiency with the nonviral vector was better than 10(4) pfu adenovirus. CONCLUSIONS: The development and characterization of the VIPER system provides a possible alternative to viral gene therapy of HCC.

Structural basis of regiospecificity of a mononuclear iron enzyme in antibiotic fosfomycin biosynthesis.

Hydroxypropylphosphonic acid epoxidase (HppE) is an unusual mononuclear iron enzyme that uses dioxygen to catalyze the oxidative epoxidation of (S)-2-hydroxypropylphosphonic acid (S-HPP) in the biosynthesis of the antibiotic fosfomycin. Additionally, the enzyme converts the R-enantiomer of the substrate (R-HPP) to 2-oxo-propylphosphonic acid. To probe the mechanism of HppE regiospecificity, we determined three X-ray structures: R-HPP with inert cobalt-containing enzyme (Co(II)-HppE) at 2.1 Å resolution; R-HPP with active iron-containing enzyme (Fe(II)-HppE) at 3.0 Å resolution; and S-HPP-Fe(II)-HppE in complex with dioxygen mimic NO at 2.9 Å resolution. These structures, along with previously determined structures of S-HPP-HppE, identify the dioxygen binding site on iron and elegantly illustrate how HppE is able to recognize both substrate enantiomers to catalyze two completely distinct reactions.

The evolution of imaging in cancer: current state and future challenges.

Molecular imaging allows for the remote, noninvasive sensing and measurement of cellular and molecular processes in living subjects. Drawing upon a variety of modalities, molecular imaging provides a window into the biology of cancer from the subcellular level to the patient undergoing a new, experimental therapy. As signal transduction cascades and protein interaction networks become clarified, an increasing number of relevant targets for cancer therapy--and imaging--become available. Although conventional imaging is already critical to the management of patients with cancer, molecular imaging will provide even more relevant information, such as early detection of changes with therapy, identification of patient-specific cellular and metabolic abnormalities, and the disposition of therapeutic, gene-tagged cells throughout the body--all of which will have a considerable impact on morbidity and mortality. This overview discusses molecular imaging in oncology, providing examples from a variety of modalities, with an emphasis on emerging techniques for translational imaging.

Complementary roles for biomarkers of biomechanical strain ST2 and N-terminal prohormone B-type natriuretic peptide in patients with ST-elevation myocardial infarction.

BACKGROUND: ST2 is a member of the interleukin-1 receptor family with a soluble form that is markedly upregulated on application of biomechanical strain to cardiac myocytes. Circulating ST2 levels are elevated in the setting of acute myocardial infarction, but the predictive value of ST2 independent of traditional clinical factors and of an established biomarker of biomechanical strain, N-terminal prohormone B-type natriuretic peptide (NT-proBNP), has not been established. METHODS AND RESULTS: We measured ST2 at baseline in 1239 patients with ST-elevation myocardial infarction from the CLopidogrel as Adjunctive ReperfusIon TherapY-Thrombolysis in Myocardial Infarction 28 (CLARITY-TIMI 28) trial. Per trial protocol, patients were to undergo coronary angiography after 2 to 8 days and were followed up for 30 days for clinical events. In contrast to NT-proBNP, ST2 levels were independent of clinical factors potentially related to chronic increased left ventricular wall stress, including age, hypertension, prior myocardial infarction, and prior heart failure; levels also were only modestly correlated with NT-proBNP (r=0.14). After adjustment for baseline characteristics and NT-proBNP levels, an ST2 level above the median was associated with a significantly greater risk of cardiovascular death or heart failure (third quartile: adjusted odds ratio, 1.42; 95% confidence interval, 0.68 to 3.57; fourth quartile: adjusted odds ratio, 3.57; 95% confidence interval, 1.87 to 6.81; P<0.0001 for trend). When both ST2 and NT-proBNP were added to a model containing traditional clinical predictors, the c statistic significantly improved from 0.82 (95% confidence interval, 0.77 to 0.87) to 0.86 (95% confidence interval, 0.81 to 0.90) (P=0.017). CONCLUSIONS: In ST-elevation myocardial infarction, high baseline ST2 levels are a significant predictor of cardiovascular death and heart failure independently of baseline characteristics and NT-proBNP, and the combination of ST2 and NT-proBNP significantly improves risk stratification. These data highlight the prognostic value of multiple, complementary biomarkers of biomechanical strain in ST-elevation myocardial infarction.

Local delivery of protease-resistant stromal cell derived factor-1 for stem cell recruitment after myocardial infarction.

BACKGROUND: Local delivery of chemotactic factors represents a novel approach to tissue regeneration. However, successful chemokine protein delivery is challenged by barriers including the rapid diffusion of chemokines and cleavage of chemokines by proteases that are activated in injured tissues. Stromal cell-derived factor-1 (SDF-1) is a well-characterized chemokine for attracting stem cells and thus a strong candidate for promoting regeneration. However, SDF-1 is cleaved by exopeptidases and matrix metalloproteinase-2, generating a neurotoxin implicated in some forms of dementia. METHODS AND RESULTS: We designed a new chemokine called S-SDF-1(S4V) that is resistant to matrix metalloproteinase-2 and exopeptidase cleavage but retains chemotactic bioactivity, reducing the neurotoxic potential of native SDF-1. To deliver S-SDF-1(S4V), we expressed and purified fusion proteins to tether the chemokine to self-assembling peptides, which form nanofibers and allow local delivery. Intramyocardial delivery of S-SDF-1(S4V) after myocardial infarction recruited CXCR4+/c-Kit+ stem cells (46+/-7 to 119+/-18 cells per section) and increased capillary density (from 169+/-42 to 283+/-27 per 1 mm2). Furthermore, in a randomized, blinded study of 176 rats with myocardial infarction, nanofiber delivery of the protease-resistant S-SDF-1(S4V) improved cardiac function (ejection fraction increased from 34.0+/-2.5% to 50.7+/-3.1%), whereas native SDF-1 had no beneficial effects. CONCLUSIONS: The combined advances of a new, protease-resistant SDF-1 and nanofiber-mediated delivery promoted recruitment of stem cells and improved cardiac function after myocardial infarction. These data demonstrate that driving chemotaxis of stem cells by local chemokine delivery is a promising new strategy for tissue regeneration.

IL-33 and ST2 comprise a critical biomechanically induced and cardioprotective signaling system.

ST2 is an IL-1 receptor family member with transmembrane (ST2L) and soluble (sST2) isoforms. sST2 is a mechanically induced cardiomyocyte protein, and serum sST2 levels predict outcome in patients with acute myocardial infarction or chronic heart failure. Recently, IL-33 was identified as a functional ligand of ST2L, allowing exploration of the role of ST2 in myocardium. We found that IL-33 was a biomechanically induced protein predominantly synthesized by cardiac fibroblasts. IL-33 markedly antagonized angiotensin II- and phenylephrine-induced cardiomyocyte hypertrophy. Although IL-33 activated NF-kappaB, it inhibited angiotensin II- and phenylephrine-induced phosphorylation of inhibitor of NF-kappa B alpha (I kappa B alpha) and NF-kappaB nuclear binding activity. sST2 blocked antihypertrophic effects of IL-33, indicating that sST2 functions in myocardium as a soluble decoy receptor. Following pressure overload by transverse aortic constriction (TAC), ST2(-/-) mice had more left ventricular hypertrophy, more chamber dilation, reduced fractional shortening, more fibrosis, and impaired survival compared with WT littermates. Furthermore, recombinant IL-33 treatment reduced hypertrophy and fibrosis and improved survival after TAC in WT mice, but not in ST2(-/-) littermates. Thus, IL-33/ST2 signaling is a mechanically activated, cardioprotective fibroblast-cardiomyocyte paracrine system, which we believe to be novel. IL-33 may have therapeutic potential for beneficially regulating the myocardial response to overload.

The interaction of thioredoxin with Txnip. Evidence for formation of a mixed disulfide by disulfide exchange.

The thioredoxin system plays an important role in maintaining a reducing environment in the cell. Recently, several thioredoxin binding partners have been identified and proposed to mediate aspects of redox signaling, but the significance of these interactions is unclear in part due to incomplete understanding of the mechanism for thioredoxin binding. Thioredoxin-interacting protein (Txnip) is critical for regulation of glucose metabolism, the only currently known function of which is to bind and inhibit thioredoxin. We explored the mechanism of the Txnip-thioredoxin interaction and present evidence that Txnip and thioredoxin form a stable disulfide-linked complex. We identified two Txnip cysteines that are important for thioredoxin binding and showed that this interaction is consistent with a disulfide exchange reaction between oxidized Txnip and reduced thioredoxin. These cysteines are not conserved in the broader family of arrestin domain-containing proteins, and we demonstrate that the thioredoxin-binding property of Txnip is unique. These data suggest that Txnip is a target of reduced thioredoxin and provide insight into the potential role of Txnip as a redox-sensitive signaling protein.

Structural insight into antibiotic fosfomycin biosynthesis by a mononuclear iron enzyme.

The biosynthetic pathway of the clinically important antibiotic fosfomycin uses enzymes that catalyse reactions without precedent in biology. Among these is hydroxypropylphosphonic acid epoxidase, which represents a new subfamily of non-haem mononuclear iron enzymes. Here we present six X-ray structures of this enzyme: the apoenzyme at 2.0 A resolution; a native Fe(II)-bound form at 2.4 A resolution; a tris(hydroxymethyl)aminomethane-Co(II)-enzyme complex structure at 1.8 A resolution; a substrate-Co(II)-enzyme complex structure at 2.5 A resolution; and two substrate-Fe(II)-enzyme complexes at 2.1 and 2.3 A resolution. These structural data lead us to suggest how this enzyme is able to recognize and respond to its substrate with a conformational change that protects the radical-based intermediates formed during catalysis. Comparisons with other family members suggest why substrate binding is able to prime iron for dioxygen binding in the absence of alpha-ketoglutarate (a co-substrate required by many mononuclear iron enzymes), and how the unique epoxidation reaction of hydroxypropylphosphonic acid epoxidase may occur.