Higher topoisomerase 2 alpha gene transcript levels predict better prognosis in GBM patients receiving temozolomide chemotherapy: identification of temozolomide as a TOP2A inhibitor

The search for molecular markers which predict response to chemotherapy is an important aspect of current neuro-oncology research. MGMT promoter methylation is the only proved marker of glioblastoma. The purpose of this study was to assess the effect of topoisomerase expression on glioblastoma survival and study the mechanisms involved. The transcript levels of all isoforms of the topoisomerase family in all grades of diffuse astrocytoma were assessed. A prospective study of patients with glioblastoma treated by a uniform treatment procedure was performed with the objective of correlating outcome with gene expression. The ability of TOP2A enzyme to relax the super coiled plasmid DNA in the presence of temozolomide was evaluated to assess its effect on TOP2A. The temozolomide cyctotoxicity of TOP2A-silenced U251 cells was assessed. The transcript levels of TOP2A, TOP2B, and TOP3A are upregulated significantly in GBM in comparison with lower grades of astrocytoma and normal brain samples. mRNA levels of TOP2A correlated significantly with survival of the patients. Higher TOP2A transcript levels in GBM patients predicted better prognosis (P = 0.043; HR = 0.889). Interestingly, we noted that temozolomide inhibited TOP2A activity in in-vitro enzyme assays. We also noted that siRNA knock down of TOP2A rendered a glioma cell line resistant to temozolomide chemotherapy. We demonstrated for the first time that temozolomide is also a TOP2A inhibitor and established that TOP2A transcript levels determine the chemosensitivity of glioblastoma to temozolomide therapy. Very high levels of TOP2A are a good prognostic indicator in GBM patients receiving temozolomide chemotherapy.

Effect of Interfacial Microstructure of Adsorbed Poly(ethylene glycol) Monooleate on Steel Substrate on Sliding Friction in Oil in Water Emulsion

The concentration of a nonionic surfactant and water pH were varied in an oil-in-water emulsion to minimize the friction coefficient between a steel ball sliding on a steel flat. At a surfactant concentration near the CMC (critical micelle concentration) the oil droplet size was found to be minimum. In this paper we study the microstructure of the surfactant molecules self-assembled on the steel substrate in water to comment on the ability of the surfactant aggregate to attract and retain oil. We find that a near semicylindrical hemimiceller microstructure with hydrocarbon tails projecting into bulk water as obtained at CMC in near neutral water is best able to capture and retain oil in yielding a low coefficient of friction.

Polymorphs and hydrates of Etoricoxib, a selective COX-2 inhibitor

The crystal structures of two polymorphs and two polymorphic hemihydrates of Etoricoxib are reported. Etoricoxib is a non-steroidal anti-inflammatory drug (NSAID) that is a selective inhibitor of COX-2. It is used in the treatment of various types of inflammation, pain and fever. Clas et al. have reported four polymorphs (labeled I through IV) and two solvates (hemi-and sesquihydrate) of the API in US patent 6,441,002 (Clas et al, US patent 6,441,002, 2002). However, no crystal structures have been reported for any of these forms. A comparison was made between the PXRD patterns reported in patent `002 and the powder spectra simulated from single crystal data. The two polymorphs characterized here correspond to form I and form IV of the patent. Form II of the patent could not be obtained by us with a variety of experimental conditions. Form III of the patent corresponds to hemihydrate II of this study. Form III is therefore not a polymorph of form I and form IV. What we have termed hemihydrate I in this study is obtained under a wide variety of conditions and it is also the only hemihydrate reported as such in the patent. Because the Etoricoxib molecule contains no conventional hydrogen bond donors, there cannot be any strong hydrogen bonds in the crystal structures of forms I and IV. The packing is accordingly characterized by weak hydrogen bonds of the C-H center dot center dot center dot O=S and C-H center dot center dot center dot N type. Thermal data were collected for form I, form IV and hemihydrate I to shed some light on relative stabilities. PXRD diffractograms show the transformation of form IV to form I at elevated temperature, indicating that form I is more stable than form IV. However, this transformation occurs only in samples of form IV that contain some form I; it does not occur in pure form IV. The formation of the two hemihydrates could follow from the known tendency of an acceptor-rich molecule to crystallize as a hydrate.

Orthogonal biofunctionalization of magnetic nanoparticles via ``clickable'' poly(ethylene glycol) silanes: a ``universal ligand'' strategy to design stealth and target-specific nanocarriers

The present work demonstrates a novel strategy to synthesize orthogonally bio-engineered magnetonanohybrids (MNPs) through the design of versatile, biocompatible linkers whose structure includes: (i) a robust anchor to bind with metal-oxide surfaces; (ii) tailored surface groups to act as spacers and (iii) a general method to implement orthogonal functionalizations of the substrate via ``click chemistry''. Ligands that possess the synthetic generality of features (i)-(iii) are categorized as ``universal ligands''. Herein, we report the synthesis of a novel, azido-terminated poly(ethylene glycol) (PEG) silane that can easily self-assemble on MNPs through hetero-condensation between surface hydroxyl groups and the silane end of the ligand, and simultaneously provide multiple clickable sites for high density, chemoselective bio-conjugation. To establish the universal-ligand-strategy, we clicked alkyl-functionalized folate onto the surface of PEGylated MNPs. By further integrating a near-infrared fluorescent (NIRF) marker (Alexa-Fluor 647) with MNPs, we demonstrated their folate-receptor mediated internalization inside cancer cells and subsequent translocation into lysosomes and mitochondria. Ex vivo NIRF imaging established that the azido-PEG-silane developed in course of the study can effectively reduce the sequestration of MNPs by macrophage organs (viz. liver and spleen). These folate-PEG-MNPs were not only stealth and noncytotoxic but their dual optical and magnetic properties aided in tracking their whereabouts through combined magnetic resonance and optical imaging. Together, these results provided a strong motivation for the future use of the ``universal ligand'' strategy towards development of ``smart'' nanohybrids for theragnostic applications.

An Inhibitor of Nonhomologous End-Joining Abrogates Double-Strand Break Repair and Impedes Cancer Progression

DNA Ligase IV is responsible for sealing of double-strand breaks (DSBs) during nonhomologous end-joining (NHEJ). Inhibiting Ligase IV could result in amassing of DSBs, thereby serving as a strategy toward treatment of cancer. Here, we identify a molecule, SCR7 that inhibits joining of DSBs in cell-free repair system. SCR7 blocks Ligase IV-mediated joining by interfering with its DNA binding but not that of T4 DNA Ligase or Ligase I. SCR7 inhibits NHEJ in a Ligase IV-dependent manner within cells, and activates the intrinsic apoptotic pathway. More importantly, SCR7 impedes tumor progression in mouse models and when coadministered with DSB-inducing therapeutic modalities enhances their sensitivity significantly. This inhibitor to target NHEJ offers a strategy toward the treatment of cancer and improvement of existing regimens.

Metabolites of PPI-2458, a selective, irreversible inhibitor of methionine aminopeptidase-2: structure determination and In vivo activity

The natural product fumagillin exhibits potent antiproliferative and antiangiogenic properties. The semisynthetic analog PPI-2458, (3R,4S,5S,6R)-5-methoxy-4-(2R,3R)-2-methyl-3-(3-methylbut-2-enyl) oxiran-2-yl]-1-oxaspiro2.5]octan-6-yl] N-(2R)-1-amino-3-methyl-1-oxobutan-2-yl]carbamate, demonstrates rapid inactivation of its molecular target, methionine aminopeptidase-2 (MetAP2), and good efficacy in several rodent models of cancer and inflammation with oral dosing despite low apparent oral bioavailability. To probe the basis of its in vivo efficacy, the metabolism of PPI-2458 was studied in detail. Reaction phenotyping identified CYP3A4/5 as the major source of metabolism in humans. Six metabolites were isolated from liver microsomes and characterized by mass spectrometry and nuclear resonance spectroscopy, and their structures were confirmed by chemical synthesis. The synthetic metabolites showed correlated inhibition of MetAP2 enzymatic activity and vascular endothelial cell growth. In an ex vivo experiment, MetAP2 inhibition in white blood cells, thymus, and lymph nodes in rats after single dosing with PPI-2458 and the isolated metabolites was found to correlate with the in vitro activity of the individual species. In a phase 1 clinical study, PPI-2458 was administered to patients with non-Hodgkin lymphoma. At 15 mg administered orally every other day, MetAP2 in whole blood was 80% inactivated for up to 48 hours, although the exposure of the parent compound was only similar to 10% that of the summed cytochrome P450 metabolites. Taken together, the data confirm the participation of active metabolites in the in vivo efficacy of PPI-2458. The structures define a metabolic pathway for PPI-2458 that is distinct from that of TNP-470 ((3R, 4S, 5S, 6R)-5-methoxy-4-(2R, 3R)-2-methyl-3-(3-methylbut-2-enyl)oxiran-2-yl]-1-oxaspiro2.5]octan-6 -yl] N-(2-chloroacetyl)carbamate). The high level of MetAP2 inhibition achieved in vivo supports the value of fumagillin-derived therapeutics for angiogenic diseases.

A cyclic peptide mimic of an RNA recognition motif of human La protein is a potent inhibitor of hepatitis C virus

Due to limited available therapeutic options, developing new lead compounds against hepatitis C virus is an urgent need. Human La protein stimulates hepatitis C virus translation through interaction with the hepatitis C viral RNA. A cyclic peptide mimicking the beta-turn of the human La protein that interacts with the viral RNA was synthesized. It inhibits hepatitis C viral RNA translation significantly better than the corresponding linear peptide at longer post-treatment times. The cyclic peptide also inhibited replication as measured by replicon RNA levels using real time RT-PCR. The cyclic peptide emerges as a promising lead compound against hepatitis C.

Quantum entropic ambiguities: Ethylene

In a quantum system, there may be many density matrices associated with a state on an algebra of observables. For each density matrix, one can compute its entropy. These are, in general, different. Therefore, one reaches the remarkable possibility that there may be many entropies for a given state R. Sorkin (private communication)]. This ambiguity in entropy can often be traced to a gauge symmetry emergent from the nontrivial topological character of the configuration space of the underlying system. It can also happen in finite-dimensional matrix models. In the present work, we discuss this entropy ambiguity and its consequences for an ethylene molecule. This is a very simple and well-known system, where these notions can be put to tests. Of particular interest in this discussion is the fact that the change of the density matrix with the corresponding entropy increase drives the system towards the maximally disordered state with maximum entropy, where Boltzman's formula applies. Besides its intrinsic conceptual interest, the simplicity of this model can serve as an introduction to a similar discussion of systems such as colored monopoles and the breaking of color symmetry.

Probing p300/CBP associated Factor (PCAF)-dependent pathways with a small molecule inhibitor

PCAF (KAT2B) belongs to the GNAT family of lysine acetyltransferases (KAT) and specifically acetylates the histone H3K9 residue and several nonhistone proteins. PCAF is also a transcriptional coactivator. Due to the lack of a PCAF KAT-specific small molecule inhibitor, the exclusive role of the acetyltransferase activity of PCAF is not well understood. Here, we report that a natural compound of the hydroxybenzoquinone class, embelin, specifically inhibits H3Lys9 acetylation in mice and inhibits recombinant PCAF-mediated acetylation with near complete specificity in vitro. Furthermore, using embelin, we have identified the gene networks that are regulated by PCAF during muscle differentiation, further highlighting the broader regulatory functions of PCAF in muscle differentiation in addition to the regulation via MyoD acetylation.

Flexible poly(vinyl alcohol-co-ethylene)/modified MMT moisture barrier composite for encapsulating organic devices

Flexible, nano-composite moisture barrier films of poly(vinyl alcohol-co-ethylene) with surface modified montmorillonite fabricated by solution casting were used to encapsulate organic devices. The composite films were characterized by FTIR, UV-visible spectroscopy and SEM imaging. Thermal and mechanical properties of the composite films were studied by DSC and UTM. Calcium degradation test was used to determine the transmission rate of water vapour through the composite films, which showed a gradual reduction from similar to 0.1 g m(-2) day(-1) to 0.0001 g m(-2) day(-1) with increasing modified montmorillonite loading in the neat copolymer. The increase in moisture barrier performance is attributed to the decreased water vapour diffusivity due to matrix-filler interactions in the composite. The accelerated aging test was carried out for non-encapsulated and encapsulated devices to evaluate the efficiency of the encapsulants. The encapsulated devices exhibited longer lifetimes indicating the efficacy of the encapsulant.

Relation Between the Diffusivity, Viscosity, and Ionic Radius of LiCl in Water, Methanol, and Ethylene Glycol: A Molecular Dynamics Simulation

A molecular dynamics (MD) investigation of LiCl in water, methanol, and ethylene glycol (EG) at 298 K is reported. Several; structural and dynamical properties of the ions as well as the solvent such as self-diffusivity, radial distribution functions, void and neck distributions, velocity autocorrelation functions, and mean residence times of solvent in the first solvation shell have been computed. The results show that the reciprocal relationship between the self-diffusivity of the ions and the viscosity is valid in almost all solvents with the exception of water. From an analysis of radial distribution functions and coordination numbers the nature of hydrogen bonding within the solvent and its influence on the void and neck distribution becomes evident. It is seen that the solvent solvent interaction is important in EG while solute solvent interactions dominate in water and methanol. From Voronoi tessellation, it is seen that the voids and necks within methanol are larger as compared to those within water or EG. On the basis of the void and neck distributions obtained from MD simulations and literature experimental data of limiting ion conductivity for various ions of different sizes we show that there is a relation between the void and neck radius on e one hand and dependence of conductivity on the ionic radius on the other. It is shown that the presence of large diameter voids and necks in methanol is responsible for maximum in limiting ion conductivity (lambda(0)) of TMA(+), while in water in EG, the maximum is seen for Rb+. In the case of monovalent anions, maximum in lambda(0) as a function ionic radius is seen for Br- in water EG but for the larger ClO4- ion in methanol. The relation between the void and neck distribution and the variation in lambda(0) with ionic radius arises via the Levitation effect which is discussed. These studies show the importance of the solvent structure and the associated void structure.

Failure of pyrolysis coils coated with anit-coking film in an ethylene cracking plant

This paper presents a specific kind of failure in ethylene cracking coils coated with anticoking film. It investigates a case in which the coils made of 35Cr 45Ni high temperature alloy failed within two years of operation. The damage occurred due to heavy oxidation in localized regions of the coil resulting in the formation of blisters, which eventually failed by cracking. The mechanism involved was determined by studying the oxidized samples under a scanning electron microscope with an energy dispersive system and is attributed to the presence of rare earth metals in the anti-coking film and inherent casting defects in the base alloy. The cerium present in the anti-coking film diffused preferentially to a defect site in the parent alloy thereby resulting in its segregation which further led to embrittlement. (C) 2014 Elsevier Ltd. All rights reserved.

Conserved water-mediated recognition and dynamics of NAD(+) (carboxamide group) to hIMPDH enzyme: water mimic approach toward the design of isoform-selective inhibitor

Inosine monophosphate dehydrogenase (IMPDH) enzyme involves in GMP biosynthesis pathway. Type I hIMPDH is expressed at lower levels in all cells, whereas type II is especially observed in acute myelogenous leukemia, chronic myelogenous leukemia cancer cells, and 10 ns simulation of the IMP-NAD(+) complex structures (PDB ID. 1B3O and 1JCN) have revealed the presence of a few conserved hydrophilic centers near carboxamide group of NAD(+). Three conserved water molecules (W1, W, and W1 `) in di-nucleotide binding pocket of enzyme have played a significant role in the recognition of carboxamide group (of NAD(+)) to D274 and H93 residues. Based on H-bonding interaction of conserved hydrophilic (water molecular) centers within IMP-NAD(+)-enzyme complexes and their recognition to NAD(+), some covalent modification at carboxamide group of di-nucleotide (NAD(+)) has been made by substituting the -CONH(2)group by -CONHNH2 (carboxyl hydrazide group) using water mimic inhibitor design protocol. The modeled structure of modified ligand may, though, be useful for the development of antileukemic agent or it could be act as better inhibitor for hIMPDH-II.

Suramin is a potent and selective inhibitor of Mycobacterium tuberculosis RecA protein and the SOS response: RecA as a potential target for antibacterial drug discovery

In eubacteria, RecA is essential for recombinational DNA repair and for stalled replication forks to resume DNA synthesis. Recent work has implicated a role for RecA in the development of antibiotic resistance in pathogenic bacteria. Consequently, our goal is to identify and characterize small-molecule inhibitors that target RecA both in vitro and in vivo. We employed ATPase, DNA strand exchange and LexA cleavage assays to elucidate the inhibitory effects of suramin on Mycobacterium tuberculosis RecA. To gain insights into the mechanism of suramin action, we directly visualized the structure of RecA nucleoprotein filaments by atomic force microscopy. To determine the specificity of suramin action in vivo, we investigated its effect on the SOS response by pull-down and western blot assays as well as for its antibacterial activity. We show that suramin is a potent inhibitor of DNA strand exchange and ATPase activities of bacterial RecA proteins with IC50 values in the low micromolar range. Additional evidence shows that suramin inhibits RecA-catalysed proteolytic cleavage of the LexA repressor. The mechanism underlying such inhibitory actions of suramin involves its ability to disassemble RecA-single-stranded DNA filaments. Notably, suramin abolished ciprofloxacin-induced recA gene expression and the SOS response and augmented the bactericidal action of ciprofloxacin. Our findings suggest a strategy to chemically disrupt the vital processes controlled by RecA and hence the promise of small molecules for use against drug-susceptible as well as drug-resistant strains of M. tuberculosis for better infection control and the development of new therapies.

Combinatorial Crystal Synthesis: Structural Landscape of Phloroglucinol:1,2-bis(4-pyridyl)ethylene and Phloroglucinol:Phenazine

A large number of crystal forms, polymorphs and pseudopolymorphs, have been isolated in the phloroglucinol-dipyridylethylene (PGL:DPE) and phloroglucinol-phenazine (PGL:PHE) systems. An understanding of the intermolecular interactions and synthon preferences in these binary systems enables one to design a ternary molecular solid that consists of PGL, PHE, and DPE, and also others where DPE is replaced by other heterocycles. Clean isolation of these ternary cocrystals demonstrates synthon amplification during crystallization. These results point to the lesser likelihood of polymorphism in multicomponent crystals compared to single-component crystals. The appearance of several crystal forms during crystallization of a multicomponent system can be viewed as combinatorial crystal synthesis with synthon selection from a solution library. The resulting polymorphs and pseudopolymorphs that are obtained constitute a crystal structure landscape.