Science.gov

Sample records for cationic lipid-based transduction

  1. Cationic Lipid-Based Nucleic Acid Vectors.

    PubMed

    Jubeli, Emile; Goldring, William P D; Pungente, Michael D

    2016-01-01

    The delivery of nucleic acids into cells remains an important laboratory cell culture technique and potential clinical therapy, based upon the initial cellular uptake, then translation into protein (in the case of DNA), or gene deletion by RNA interference (RNAi). Although viral delivery vectors are more efficient, the high production costs, limited cargo capacity, and the potential for clinical adverse events make nonviral strategies attractive. Cationic lipids are the most widely applied and studied nonviral vectors; however, much remains to be solved to overcome limitations of these systems. Advances in the field of cationic lipid-based nucleic acid (lipoplex) delivery rely upon the development of robust and reproducible lipoplex formulations, together with the use of cell culture assays. This chapter provides detailed protocols towards the formulation, delivery, and assessment of in vitro cationic lipid-based delivery of DNA. PMID:27436310

  2. Physical Chemical and Biomolecular Methods for the Optimization of Cationic Lipid-Based Lipoplexes In Vitro for the Gene Therapy Applications.

    PubMed

    Misra, Santosh K; Bhattacharya, Santanu

    2016-01-01

    Preparation and application protocols play a very important role while optimizing the cationic lipid-based lipoplexes in vitro. These protocols serve as the basis for the betterment of the lipoplexes with regard to their successful application in animals and eventually human subjects. Starting from the chemical structures of used cationic lipids (CLs), optimization of the additive inclusions, methods of nanoparticle (lipoplex) formation, presence of blood serum, time intervals of lipoplex incubation, and type of efficiency read-outs in various conditions play important roles in reaching insightful conclusions. Such steps of summarizing protocols and requirements of the pertinent events focus on getting improved lipoplexes for achieving optimal effects in terms of post transfection gene and protein expression. The progression of optimization and efficiency evaluation lead to predictable structure-method-activity relationship with involvement of various feedback principles including physical chemical and biomolecular evaluations before and after the use of lipoplexes in biological systems. This chapter discusses some of the focused strategies for the establishment of lipoplexes for a better post transfection activity with reduced risk of failure. PMID:27436309

  3. In vivo time-dependent gene expression of cationic lipid-based emulsion as a stable and biocompatible non-viral gene carrier.

    PubMed

    Kwon, Seok Min; Nam, Hae Yun; Nam, Taehwan; Park, Kyeongsoon; Lee, Seulki; Kim, Kwangmeyung; Kwon, Ick Chan; Kim, Joon; Kim, Jun; Kang, Dongmin; Park, Jae Hyung; Jeong, Seo Young

    2008-05-22

    To make stable and biocompatible non-viral gene carriers for therapeutic gene therapy, we developed a cationic lipid-based emulsion (CLE) prepared by an oil-in-water (O/W) emulsion method, wherein squalene oil was used as an oil core and the cationic lipid, 1,2-dioleoyl-sn-glycero-3-trimethylammonium-propane (DOTAP), was employed as an emulsifier. To evaluate in vivo characteristics such as toxicity and time-dependent gene expression, a bioluminescence reporter gene in pCMV-luc plasmid DNA was simply mixed with CLE in aqueous condition, resulting in a CLE/DNA complex. The CLE/DNA complex was optimized to form a compact and stable nano-sized particle by adding different amounts of plasmid DNA, and an optimal cationic lipid-to-DNA (C/D) weight ratio of 4 was identified. Freshly prepared CLE/DNA complex, with a C/D of 4, showed a high transfection efficiency and minimal cytotoxicity in vitro, compared to controls of a liposome (DOTAP)/DNA complex and a branched poly(ethyleneimine) (Mw=25 kDa) (bPEI)/DNA complex, respectively. The in vivo characteristics of the CLE/DNA complex were evaluated after intravenous injection into Balb/c mice. Time-dependent gene expression data in vivo were obtained using a non-invasive, whole animal bioluminescence imaging system. These data showed that the CLE/DNA complex offered prolonged high-level gene expression for 1 week, particularly in the liver and spleen. On the other hand, the controls of DOTAP/DNA complex and bPEI/DNA complex showed a relatively lower gene expression, because of the unstable and toxic properties of the control carriers. Our in vivo gene expression data demonstrate the potential of the CLE/DNA complex as a non-viral gene carrier for in vivo gene delivery.

  4. Inorganic Cation Transport and Energy Transduction in Enterococcus hirae and Other Streptococci

    PubMed Central

    Kakinuma, Yoshimi

    1998-01-01

    Energy metabolism by bacteria is well understood from the chemiosmotic viewpoint. We know that bacteria extrude protons across the plasma membrane, establishing an electrochemical potential that provides the driving force for various kinds of physiological work. Among these are the uptake of sugars, amino acids, and other nutrients with the aid of secondary porters and the regulation of the cytoplasmic pH and of the cytoplasmic concentration of potassium and other ions. Bacteria live in diverse habitats and are often exposed to severe conditions. In some circumstances, a proton circulation cannot satisfy their requirements and must be supplemented with a complement of primary transport systems. This review is concerned with cation transport in the fermentative streptococci, particularly Enterococcus hirae. Streptococci lack respiratory chains, relying on glycolysis or arginine fermentation for the production of ATP. One of the major findings with E. hirae and other streptococci is that ATP plays a much more important role in transmembrane transport than it does in nonfermentative organisms, probably due to the inability of this organism to generate a large proton potential. The movements of cations in streptococci illustrate the interplay between a variety of primary and secondary modes of transport. PMID:9841664

  5. Lipid-Based Nanocarriers for RNA Delivery

    PubMed Central

    Xue, Hui Yi; Guo, Pengbo; Wen, Wu-Cheng; Wong, Ho Lun

    2015-01-01

    RNA-interference (RNAi) agents such as small-interfering RNA (siRNA) and micro-RNA (miRNA) have strong potential as therapeutic agents for the treatment of a broad range of diseases such as malignancies, infections, autoimmune diseases and neurological diseases that are associated with undesirable gene expression. In recent years, several clinical trials of RNAi therapeutics especially siRNAs have been conducted with limited success so far. For systemic administration of these poorly permeable and easily degradable macromolecules, it is obvious that a safe and efficient delivery platform is highly desirable. Because of high biocompatibility, biodegradability and solid track record for clinical use, nanocarriers made of lipids and/or phospholipids have been commonly employed to facilitate RNA delivery. In this article, the key features of the major sub-classes of lipid-based nanocarriers, e.g. liposomes, lipid nanoparticles and lipid nanoemulsions, will be reviewed. Focus of the discussion is on the various challenges researchers face when developing lipid-based RNA nanocarriers, such as the toxicity of cationic lipids and issues related to PEGylated lipids, as well as the strategies employed in tackling these challenges. It is hoped that by understanding more about the pros and cons of these most frequently used RNA delivery systems, the pharmaceutical scientists, biomedical researchers and clinicians will be more successful in overcoming some of the obstacles that currently limit the clinical translation of RNAi therapy.

  6. Generalized transduction.

    PubMed

    Thierauf, Anne; Perez, Gerardo; Maloy, And Stanley

    2009-01-01

    Transduction is the process in which bacterial DNA is transferred from one bacterial cell to another by means of a phage particle. There are two types of transduction, generalized transduction and specialized transduction. In this chapter two of the best-studied systems - Escherichia coli-phage P1, and Salmonella enterica-phage P22 - are discussed from theoretical and practical perspectives.

  7. Phage Transduction.

    PubMed

    Goh, Shan

    2016-01-01

    Bacteriophages mediate horizontal gene transfer through a mechanism known as transduction. Phage transduction carried out in the laboratory involves a bacterial donor and a recipient, both of which are susceptible to infection by the phage of interest. Phage is propagated in the donor, concentrated, and exposed transiently to recipient at different multiplicity of infection ratios. Transductants are selected for the desired phenotype by culture on selective medium. Here we describe transduction of ermB conferring resistance to erythromycin by the C. difficile phage ϕC2. PMID:27507341

  8. Hybrid lipid-based nanostructures

    NASA Astrophysics Data System (ADS)

    Dayani, Yasaman

    Biological membranes serve several important roles, such as structural support of cells and organelles, regulation of ionic and molecular transport, barriers to non-mediated transport, contact between cells within tissues, and accommodation of membrane proteins. Membrane proteins and other vital biomolecules incorporated into the membrane need a lipid membrane to function. Due to importance of lipid bilayers and their vital function in governing many processes in the cell, the development of various models as artificial lipid membranes that can mimic cell membranes has become a subject of great interest. Using different models of artificial lipid membranes, such as liposomes, planar lipid bilayers and supported or tethered lipid bilayers, we are able to study many biophysical processes in biological membranes. The ability of different molecules to interact with and change the structure of lipid membranes can be also investigated in artificial lipid membranes. An important application of lipid bilayer-containing interfaces is characterization of novel membrane proteins for high throughput drug screening studies to investigate receptor-drug interactions and develop biosensor systems. Membrane proteins need a lipid bilayer environment to preserve their stability and functionality. Fabrication of materials that can interact with biomolecules like proteins necessitates the use of lipid bilayers as a mimic of cell membranes. The objective of this research is to develop novel hybrid lipid-based nanostructures mimicking biological membranes. Toward this aim, two hybrid biocompatible structures are introduced: lipid bilayer-coated multi-walled carbon nanotubes (MWCNTs) and hydrogel-anchored liposomes with double-stranded DNA anchors. These structures have potential applications in biosensing, drug targeting, drug delivery, and biophysical studies of cell membranes. In the first developed nanostructure, lipid molecules are covalently attached to the surfaces of MWCNTs, and

  9. Actinide cation-cation complexes

    SciTech Connect

    Stoyer, N.J.; Seaborg, G.T.

    1994-12-01

    The +5 oxidation state of U, Np, Pu, and Am is a linear dioxo cation (AnO{sub 2}{sup +}) with a formal charge of +1. These cations form complexes with a variety of other cations, including actinide cations. Other oxidation states of actinides do not form these cation-cation complexes with any cation other than AnO{sub 2}{sup +}; therefore, cation-cation complexes indicate something unique about AnO{sub 2}{sup +} cations compared to actinide cations in general. The first cation-cation complex, NpO{sub 2}{sup +}{center_dot}UO{sub 2}{sup 2+}, was reported by Sullivan, Hindman, and Zielen in 1961. Of the four actinides that form AnO{sub 2}{sup +} species, the cation-cation complexes of NpO{sub 2}{sup +} have been studied most extensively while the other actinides have not. The only PuO{sub 2}{sup +} cation-cation complexes that have been studied are with Fe{sup 3+} and Cr{sup 3+} and neither one has had its equilibrium constant measured. Actinides have small molar absorptivities and cation-cation complexes have small equilibrium constants; therefore, to overcome these obstacles a sensitive technique is required. Spectroscopic techniques are used most often to study cation-cation complexes. Laser-Induced Photacoustic Spectroscopy equilibrium constants for the complexes NpO{sub 2}{sup +}{center_dot}UO{sub 2}{sup 2+}, NpO{sub 2}{sup +}{center_dot}Th{sup 4+}, PuO{sub 2}{sup +}{center_dot}UO{sub 2}{sup 2+}, and PuO{sub 2}{sup +}{center_dot}Th{sup 4+} at an ionic strength of 6 M using LIPAS are 2.4 {plus_minus} 0.2, 1.8 {plus_minus} 0.9, 2.2 {plus_minus} 1.5, and {approx}0.8 M{sup {minus}1}.

  10. Lipid-based transfection reagents can interfere with cholesterol biosynthesis.

    PubMed

    Danielli, Mauro; Marinelli, Raúl A

    2016-02-15

    Lipid-based transfection reagents are widely used for delivery of small interfering RNA into cells. We examined whether the commonly used commercial transfection reagents DharmaFECT-4 and Lipofectamine 2000 can interfere with lipid metabolism by studying cholesterogenesis. Cholesterol de novo synthesis from [(14)C]acetate was assessed in human hepatocyte-derived Huh-7 cells. The results revealed that DharmaFECT, but not Lipofectamine, markedly inhibited cholesterol biosynthesis by approximately 70%. Cell viability was not significantly altered. These findings suggest that caution is required in the choice of certain lipid-based transfection reagents for gene silencing experiments, particularly when assessing cholesterol metabolism.

  11. Lipid-based Transfection Reagents Exhibit Cryo-induced Increase in Transfection Efficiency

    PubMed Central

    Sork, Helena; Nordin, Joel Z; Turunen, Janne J; Wiklander, Oscar PB; Bestas, Burcu; Zaghloul, Eman M; Margus, Helerin; Padari, Kärt; Duru, Adil D; Corso, Giulia; Bost, Jeremy; Vader, Pieter; Pooga, Margus; Smith, CI Edvard; Wood, Matthew JA; Schiffelers, Raymond M; Hällbrink, Mattias; Andaloussi, Samir EL

    2016-01-01

    The advantages of lipid-based transfection reagents have permitted their widespread use in molecular biology and gene therapy. This study outlines the effect of cryo-manipulation of a cationic lipid-based formulation, Lipofectamine 2000, which, after being frozen and thawed, showed orders of magnitude higher plasmid delivery efficiency throughout eight different cell lines, without compromising cell viability. Increased transfection efficiency with the freeze-thawed reagent was also seen with 2'-O-methyl phosphorothioate oligonucleotide delivery and in a splice-correction assay. Most importantly, a log-scale improvement in gene delivery using the freeze-thawed reagent was seen in vivo. Using three different methods, we detected considerable differences in the polydispersity of the different nucleic acid complexes as well as observed a clear difference in their surface spreading and sedimentation, with the freeze-thawed ones displaying substantially higher rate of dispersion and deposition on the glass surface. This hitherto overlooked elevated potency of the freeze-thawed reagent facilitates the targeting of hard-to-transfect cells, accomplishes higher transfection rates, and decreases the overall amount of reagent needed for delivery. Additionally, as we also saw a slight increase in plasmid delivery using other freeze-thawed transfection reagents, we postulate that freeze-thawing might prove to be useful for an even wider variety of transfection reagents. PMID:27111416

  12. Transduction in Bacillus subtilis.

    PubMed

    THORNE, C B

    1962-01-01

    Thorne, Curtis B. (Fort Detrick, Frederick, Md.). Transduction in Bacillus subtilis. J. Bacteriol. 83:106-111. 1962.-A bacteriophage, SP-10, isolated from soil carries out general transduction in Bacillus subtilis. Phage propagated on a streptomycin-resistant mutant of the wild-type strain W-23 was capable of transducing to prototrophy strain 168 (indole(-)), as well as all of the auxotrophic mutants of W-23-S(r) tested, which included mutants requiring arginine, histidine, adenine, guanine, thiamine, leucine, or methionine. Although strain 168 was transduced by phage SP-10, lytic activity on this strain could not be detected and attempts to propagate the phage on it failed. Transductions occurred at frequencies in the range of 10(-6) to 10(-5) per plaque-forming unit. Homologous phage was ineffective, deoxyribonuclease had no effect on the frequency of transduction, and transduction was prevented by the addition of phage antiserum. Phage SP-10 was capable of lysogenizing strain W-23-S(r), and this condition was maintained through repeated growth and sporulation cycles in potato-extract medium. Although heating at 65 C for 60 min inactivated free phage particles, spores retained their lysogenic condition after such heat treatment. When heat-treated spores of the lysogenic cultures were used as inocula for growth in a nutrient broth-yeast extract-glucose medium, filtrates contained 10(9), or more, phage particles per ml.

  13. Recombinant adeno-associated virus-mediated high-efficiency, transient expression of the murine cationic amino acid transporter (ecotropic retroviral receptor) permits stable transduction of human HeLa cells by ecotropic retroviral vectors.

    PubMed Central

    Bertran, J; Miller, J L; Yang, Y; Fenimore-Justman, A; Rueda, F; Vanin, E F; Nienhuis, A W

    1996-01-01

    Adeno-associated virus has a broad host range, is nonpathogenic, and integrates into a preferred location on chromosome 19, features that have fostered development of recombinant adeno-associated viruses (rAAV) as gene transfer vectors for therapeutic applications. We have used an rAAV to transfer and express the murine cationic amino acid transporter which functions as the ecotropic retroviral receptor, thereby rendering human cells conditionally susceptible to infection by an ecotropic retroviral vector. The proportion of human HeLa cells expressing the receptor at 60 h varied as a function of the multiplicity of infection (MOI) with the rAAV. Cells expressing the ecotropic receptor were efficiently transduced with an ecotropic retroviral vector encoding a nucleus-localized form of beta-galactosidase. Cells coexpressing the ecotropic receptor and nucleus-localized beta-galactosidase were isolated by fluorescence-activated cell sorting, and cell lines were recovered by cloning at limiting dilution. After growth in culture, all clones contained the retroviral vector genome, but fewer than 10% (3 of 47) contained the rAAV genome and continued to express the ecotropic receptor. The ecotropic receptor coding sequences in the rAAV genome were under the control of a tetracycline-modulated promoter. In the presence of tetracycline, receptor expression was low and the proportion of cells transduced by the ecotropic retroviral vector was decreased. Modulation of receptor expression was achieved with both an episomal and an integrated form of the rAAV genome. These data establish that functional gene expression from an rAAV genome can occur transiently without genome integration. PMID:8794313

  14. Unstable generalized transduction in Achromobacter.

    PubMed

    Woods, D R; Thomson, J A

    1975-05-01

    Six auxotrophic markers of a halotolerant collagenolytic strain of Achromobacter were transduced by four alpha hages. Abortive transduction was also demonstrated. The generalized transduction system is unusual as the transductants were unstable, characteristic of transduction by lysogeny. The Achromobacter strain is a cryptic lysogen for alpha and purified transductants were either sensitive or resistant to alpha. Purified clones from four resistant transductants and one sensitive transductant liberated phage spontaneously. The host ranges of these spontaneous phage differed from that of the alpha phage used for the transduction experiment. Some initially resistant transductants became simi-sensitive to alpha (efficiency to plating) e.o.p. (10minus-1 to 10minus-2) after repeated cloning.

  15. CSF-1 signal transduction.

    PubMed

    Hamilton, J A

    1997-08-01

    Colony-stimulating factor-1 (CSF-1) or macrophage-CSF (M-CSF) is a growth factor involved in the proliferation, differentiation, and activation of cells of the monocyte/macrophage lineage. Its receptor is the homodimeric, tyrosine kinase product of the c-fms proto-oncogene, which contains a so-called kinase insert domain. This review focuses mainly on recent studies of signal transduction events that are initiated on interaction of CSF-1 and its receptor. A summary is given of the tyrosine autophosphorylation sites on c-Fms identified to date, including their interaction with various substrates and their possible significance for signal transduction and cellular function. In addition, the signal transduction pathways that have been identified to lie downstream of activated c-Fms are reviewed. Although it is apparent that there have been many recent significant developments in our understanding of CSF-1 signaling, a number of examples are mentioned of significant discrepancies in the literature, some possible reasons for which can sometimes be offered. It is also apparent that any particular biochemical response or signal transduction pathway, even though widespread in other ligand receptor/cellular systems, including those with similar receptor structures to c-Fms, may not be relevant to CSF-1 signaling. The relevance of any potentially important molecular signaling pathway activated by CSF-1 in cells in vitro will ultimately have to be related to the functions of monocytes/macrophages in vivo.

  16. Lipid Based Nanosystems for Curcumin: Past, Present and Future.

    PubMed

    Nayak, Aditya P; Mills, Tom; Norton, Ian

    2016-01-01

    Curcumin is one of the principle bioactive compounds used in the ayurvedic medicine system that has the history of over 5000 years for human use. Curcumin an "Indian Gold" is used to treat simple ailments like the common cold to severe life threatening diseases like cancer, and HIV. Though its contribution is immense for the health protection and disease prevention, its clinical use is limited due to its susceptible nature to alkaline pH, high temperature, presence of oxygen and light. Hence it becomes extremely difficult to maintain its bioactivity during processing, storage and consumption. Recent advancements in the application of nanotechnology to curcumin offer an opportunity to enhance its stability, bioactivity and to overcome its pharmacokinetic mismatch. This in turn helps to bridge the gaps that exist between its bench top research data to its clinical findings. Among the various types of nano/micro delivery systems, lipid based delivery systems are well studied and are the best suited delivery systems to enhance the stability and pharmacokinetic profile of curcumin both for pharma and the food application. In the current review, effort will be made to recapitulate the work done in the past to use lipid based delivery systems (liposomes, solid lipid nanoparticles, and emulsions) to enhance the application of curcumin for health promotion and disease prevention. Further, future prospects for the utilization of these lipid-based delivery systems will be discussed in detail. PMID:27306091

  17. Considerations in developing lipid-based nutrient supplements for prevention of undernutrition: experience from the International Lipid-Based Nutrient Supplements (iLANS) Project.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The International Lipid-Based Nutrient Supplements (iLiNS) Project began in 2009 with the goal of contributing to the evidence base regarding the potential of lipid-based nutrient supplements (LNS) to prevent undernutrition in vulnerable populations. The first project objective was the development o...

  18. A highlight on lipid based nanocarriers for transcutaneous immunization.

    PubMed

    Nasr, Maha; Abdel-Hamid, Sameh; Alyoussef, Abdullah A

    2015-01-01

    Transcutaneous vaccination has become a widely used technique for providing immunity against several types of pathogens, taking advantage of the immune components found in the skin. The success in the field of vaccination has not only relied on the type of antigen and adjuvant delivered, but also on how they are delivered. In this regard, particulate carriers, especially nanoparticles have evoked considerable interest, owing to the desirable properties that they impart to the substance being delivered. The presentation of antigens by the nanoparticles mimics the presentation of the immunogen by the pathogen; hence, it creates a similar immune response. Furthermore, nanoparticles protect the antigen from degradation and allow its prolonged release, which maximizes its exposure to the immune cells. The most commonly used materials for the formulation of nanoparticles are either polymer-based or lipid based. This review will focus on the lipid based nanocarriers, either vesicular such as liposomes, transfersomes, and ethosomes, or non-vesicular such as cubosomes, solid lipid nanoparticles, nano-structured lipid carriers, solid in oil nanodispersions, lipoplexes, and hybrid polymeric-lipidic systems. The applications of these carriers in the field of transcutaneous immunization will be discussed in this review as well. PMID:25658381

  19. Cell-penetrating peptides: Possible transduction mechanisms and therapeutic applications

    PubMed Central

    GUO, ZHENGRONG; PENG, HUANYAN; KANG, JIWEN; SUN, DIANXING

    2016-01-01

    Cell-penetrating peptides (CPPs), also known as protein transduction domains, are a class of diverse peptides with 5–30 amino acids. CPPs are divided into cationic, amphipathic and hydrophobic CPPs. They are able to carry small molecules, plasmid DNA, small interfering RNA, proteins, viruses, imaging agents and other various nanoparticles across the cellular membrane, resulting in internalization of the intact cargos. However, the mechanisms of CPP internalization remain to be elucidated. Recently, CPPs have received considerable attention due to their high transduction efficiency and low cytotoxicity. These peptides have a significant potential for diagnostic and therapeutic applications, such as delivery of fluorescent or radioactive compounds for imaging, delivery of peptides and proteins for therapeutic application, and delivery of molecules into induced pluripotent stem cells for directing differentiation. The present study reviews the classifications and transduction mechanisms of CPPs, as well as their potential applications. PMID:27123243

  20. Protein phylogenetic analysis of Ca(2+)/cation antiporters and insights into their evolution in plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cation transport is a critical process in all organisms and is essential for mineral nutrition, ion stress tolerance, and signal transduction. Transporters that are members of the Ca(2+)/cation antiporter (CaCA) superfamily are involved in the transport of Ca(2+) and/or other cations using the count...

  1. The Deleterious Effects of Oxidative and Nitrosative Stress on Palmitoylation, Membrane Lipid Rafts and Lipid-Based Cellular Signalling: New Drug Targets in Neuroimmune Disorders.

    PubMed

    Morris, Gerwyn; Walder, Ken; Puri, Basant K; Berk, Michael; Maes, Michael

    2016-09-01

    Oxidative and nitrosative stress (O&NS) is causatively implicated in the pathogenesis of Alzheimer's and Parkinson's disease, multiple sclerosis, chronic fatigue syndrome, schizophrenia and depression. Many of the consequences stemming from O&NS, including damage to proteins, lipids and DNA, are well known, whereas the effects of O&NS on lipoprotein-based cellular signalling involving palmitoylation and plasma membrane lipid rafts are less well documented. The aim of this narrative review is to discuss the mechanisms involved in lipid-based signalling, including palmitoylation, membrane/lipid raft (MLR) and n-3 polyunsaturated fatty acid (PUFA) functions, the effects of O&NS processes on these processes and their role in the abovementioned diseases. S-palmitoylation is a post-translational modification, which regulates protein trafficking and association with the plasma membrane, protein subcellular location and functions. Palmitoylation and MRLs play a key role in neuronal functions, including glutamatergic neurotransmission, and immune-inflammatory responses. Palmitoylation, MLRs and n-3 PUFAs are vulnerable to the corruptive effects of O&NS. Chronic O&NS inhibits palmitoylation and causes profound changes in lipid membrane composition, e.g. n-3 PUFA depletion, increased membrane permeability and reduced fluidity, which together lead to disorders in intracellular signal transduction, receptor dysfunction and increased neurotoxicity. Disruption of lipid-based signalling is a source of the neuroimmune disorders involved in the pathophysiology of the abovementioned diseases. n-3 PUFA supplementation is a rational therapeutic approach targeting disruptions in lipid-based signalling.

  2. Lipid-based nanocarriers for breast cancer treatment - comprehensive review.

    PubMed

    Talluri, Siddartha Venkata; Kuppusamy, Gowthamarajan; Karri, Veera Venkata Satyanarayana Reddy; Tummala, Shashank; Madhunapantula, SubbaRao V

    2016-05-01

    Breast cancer is the second leading cancer-related disease as the most common non-cutaneous malignancy among women. Curative options for breast cancer are limited, therapeutically substantial and associated with toxicities. Emerging nanotechnologies exhibited the possibility to treat or target breast cancer. Among the nanoparticles, various lipid nanoparticles namely, liposomes, solid lipid nanoparticles, nanostructured lipid carriers and lipid polymer hybrid nanoparticles have been developed over the years for the breast cancer therapy and evidences are documented. Concepts are confined in lab scale, which needs to be transferred to large scale to develop active targeting nanomedicine for the clinical utility. So, the present review highlights the recently published studies in the development of lipid-based nanocarriers for breast cancer treatment. PMID:26430913

  3. Generalized Transduction in CAULOBACTER CRESCENTUS.

    PubMed

    Ely, B; Johnson, R C

    1977-11-01

    Two closely related bacteriophage, varphiCr30 and varphiCr35, are the first bacteriophage shown to mediate generalized transduction in Caulobacter crescentus. Unlike most other transducing phage, they are virulent and do not form any sort of lysogenic relationship with their host. However, they are rather inefficient at adsorption, so that transductants have a good chance of survival. The phage particles have a head 80 nm in diameter and a contractile tail 140 nm in length. Procedures for growth and transduction with varphiCr30 are relatively simple; thus, it will be of great value for the genetic analysis of C. crescentus.

  4. Generalized transduction by lytic bacteriophages.

    PubMed

    Waddell, Thomas E; Franklin, Kristyn; Mazzocco, Amanda; Kropinski, Andrew M; Johnson, Roger P

    2009-01-01

    As interest in lytic phages as antimicrobial therapies or as treatments to reduce environmental contamination with pathogenic bacteria has increased, so has the need to determine if the use of lytic phages may lead to dissemination of virulence factors through generalized transduction, as occurs with temperate phages. Here we describe simple methods we have developed to determine if a lytic phage, rV5, can mediate generalized transduction in Escherichia coli O157:H7. These sensitive methods can be easily adapted to study generalized transduction between virulent and avirulent strains of bacteria.

  5. Lipoic acid functionalized amino acids cationic lipids as gene vectors.

    PubMed

    Su, Rong-Chuan; Liu, Qiang; Yi, Wen-Jing; Zheng, Li-Ting; Zhao, Zhi-Gang

    2016-10-01

    A series of reducible cationic lipids 4a-4f with different amino acid polar-head groups were prepared. The novel lipid contains a hydrophobic lipoic acid (LA) moiety, which can be reduced under reductive conditions to release of the encapsulated plasmid DNA. The particle size, zeta potential and cellular uptake of lipoplexes formed with DNA, as well as the transfection efficacy (TE) were characterized. The TE of the cationic lipid based on arginine was especially high, and was 2.5times higher than that of a branched polyethylenimine in the presence of 10% serum.

  6. Polyethyleneimine-coating enhances adenoviral transduction of mesenchymal stem cells.

    PubMed

    Yao, Xinglei; Zhou, Na; Wan, Li; Su, Xiaodong; Sun, Zhao; Mizuguchi, Hiroyuki; Yoshioka, Yasuo; Nakagawa, Shinsaku; Zhao, Robert Chunhua; Gao, Jian-Qing

    2014-05-01

    Mesenchymal stem cells (MSCs) are non-hematopoietic cells with multi-lineage potential, which makes them attractive targets for regenerative medicine applications. Efficient gene transfer into MSCs is essential for basic research in developmental biology and for therapeutic applications involving gene-modification in regenerative medicine. Adenovirus vectors (Advs) can efficiently and transiently introduce an exogenous gene into many cell types via their primary receptors, the coxsackievirus and adenovirus receptors (CARs), but not into MSCs, which lack CAR expression. To overcome this problem, an Adv coated with cationic polymer polyethyleneimine (PEI) was developed. In this study, we demonstrated that PEI coating with an optimal ratio can enhance adenoviral transduction of MSCs without cytotoxicity. We also investigated the physicochemical properties and internalization mechanisms of the PEI-coated Adv. These results could help to evaluate the potentiality of the PEI-coated Adv as a prototype vector for efficient and safe transduction into MSCs. PMID:24727452

  7. Molecular basis of mechanosensory transduction

    NASA Astrophysics Data System (ADS)

    Gillespie, Peter G.; Walker, Richard G.

    2001-09-01

    Mechanotransduction - a cell's conversion of a mechanical stimulus into an electrical signal - reveals vital features of an organism's environment. From hair cells and skin mechanoreceptors in vertebrates, to bristle receptors in flies and touch receptors in worms, mechanically sensitive cells are essential in the life of an organism. The scarcity of these cells and the uniqueness of their transduction mechanisms have conspired to slow molecular characterization of the ensembles that carry out mechanotransduction. But recent progress in both invertebrates and vertebrates is beginning to reveal the identities of proteins essential for transduction.

  8. Generalized transduction in Rhizobium meliloti.

    PubMed

    Sik, T; Horváth, J; Chatterjee, S

    1980-01-01

    The phage 11 of R. meliloti performs generalized transduction. This was confirmed by the variety of single markers transferred and by separating transducing particles containing BUdR-labelled bacterial DNA. The transduction frequencies depended on the marker. Linked alleles were mapped by cotransduction on fragments of bacterial DNA equal in size to the phage DNA. With crosses between antibiotic resistancy and auxotrophic markers a partial map was constructed with str, cml, pur-19, and leu-44 sites. With a few multi-auxotrophic mutants linkage data of conjugation were compared with the linkage by cotransduction.

  9. Specially-Made Lipid-Based Assemblies for Improving Transmembrane Gene Delivery: Comparison of Basic Amino Acid Residue Rich Periphery.

    PubMed

    Jiang, Qian; Yue, Dong; Nie, Yu; Xu, Xianghui; He, Yiyan; Zhang, Shiyong; Wagner, Ernst; Gu, Zhongwei

    2016-06-01

    Cationic lipid based assemblies provide a promising platform for effective gene condensation into nanosized particles, and the peripheral properties of the assemblies are vital for complexation and interaction with physical barriers. Here, we report three cationic twin head lipids, and each of them contains a dioleoyl-glutamate hydrophobic tail and a twin polar head of lysine, arginine, or histidine. Such lipids were proven to self-assemble in aqueous solution with well-defined nanostructures and residual amino-, guanidine-, or imidazole-rich periphery, showing strong buffering capacity and good liquidity. The assemblies with arginine (RL) or lysine (KL) periphery exhibited positive charges (∼+35 mV) and complete condensation of pDNA into nanosized complexes (∼120 nm). In contrast, assemblies composed of histidine-rich lipids (HL) showed relatively low cationic electric potential (∼+10 mV) and poor DNA binding ability. As expected, the designed RL assemblies with guanidine-rich periphery enhanced the in vitro gene transfection up to 190-fold as compared with the golden standard PEI25k and Lipofectamine 2000, especially in the presence of serum. Meanwhile, interaction with cell and endo/lysosome membrane also revealed the superiority of RL complexes, that the guanidine-rich surface efficiently promoted transmembrane process in cellular internalization and endosomal disruption. More importantly, RL complexes also succeeded beyond others in vivo with significantly (∼7-fold) enhanced expression in HepG2 tumor xenografts in mice, as well as stronger green fluorescence protein imaging in isolated tumors and tumor frozen sections. PMID:27097286

  10. Applications of lipid based formulation technologies in the delivery of biotechnology-based therapeutics.

    PubMed

    du Plessis, Lissinda H; Marais, Etienne B; Mohammed, Faruq; Kotzé, Awie F

    2014-01-01

    In the last decades several new biotechnologically-based therapeutics have been developed due to progress in genetic engineering. A growing challenge facing pharmaceutical scientists is formulating these compounds into oral dosage forms with adequate bioavailability. An increasingly popular approach to formulate biotechnology-based therapeutics is the use of lipid based formulation technologies. This review highlights the importance of lipid based drug delivery systems in the formulation of oral biotechnology based therapeutics including peptides, proteins, DNA, siRNA and vaccines. The different production procedures used to achieve high encapsulation efficiencies of the bioactives are discussed, as well as the factors influencing the choice of excipient. Lipid based colloidal drug delivery systems including liposomes and solid lipid nanoparticles are reviewed with a focus on recent advances and updates. We further describe microemulsions and self-emulsifying drug delivery systems and recent findings on bioactive delivery. We conclude the review with a few examples on novel lipid based formulation technologies. PMID:25091118

  11. Meeting Report: Teaching Signal Transduction

    ERIC Educational Resources Information Center

    Kramer, IJsbrand; Thomas, Geraint

    2006-01-01

    In July, 2005, the European Institute of Chemistry and Biology at the campus of the University of Bordeaux, France, hosted a focused week of seminars, workshops, and discussions around the theme of "teaching signal transduction." The purpose of the summer school was to offer both junior and senior university instructors a chance to reflect on the…

  12. SPP1-mediated plasmid transduction.

    PubMed Central

    Canosi, U; Lüder, G; Trautner, T A

    1982-01-01

    The virulent Bacillus subtilis phage SPP1 transduces plasmid DNA. Plasmid-transducing phages contain only plasmid DNA. Such DNA represents a concatemer of monomeric plasmid molecules with the molecular weight of mature SPP1 DNA. Biological parameters of plasmid transduction are described. Images PMID:6292508

  13. Generalized transduction in Streptomyces coelicolor.

    PubMed

    Burke, J; Schneider, D; Westpheling, J

    2001-05-22

    We report the isolation of generalized transducing phages for Streptomyces species able to transduce chromosomal markers or plasmids between derivatives of Streptomyces coelicolor, the principal genetic model system for this important bacterial genus. We describe four apparently distinct phages (DAH2, DAH4, DAH5, and DAH6) that are capable of transducing multiple chromosomal markers at frequencies ranging from 10(-5) to 10(-9) per plaque-forming unit. The phages contain DNA ranging in size from 93 to 121 kb and mediate linked transfer of genetic loci at neighboring chromosomal sites sufficiently close to be packaged within the same phage particle. The key to our ability to demonstrate transduction by these phages was the establishment of conditions expected to severely reduce superinfection killing during the selection of transductants. The host range of these phages, as measured by the ability to form plaques, extends to species as distantly related as Streptomyces avermitilis and Streptomyces verticillus, which are among the most commercially important species of this genus. Transduction of plasmid DNA between S. coelicolor and S. verticillus was observed at frequencies of approximately 10(-4) transductants per colony-forming unit.

  14. Thapsigargin activates univalent- and bivalent-cation entry in human neutrophils by a SK&F I3 96365- and Gd3+-sensitive pathway and is a partial secretagogue: involvement of pertussis-toxin-sensitive G-proteins and protein phosphatases 1/2A and 2B in the signal-transduction pathway.

    PubMed Central

    Wenzel-Seifert, K; Krautwurst, D; Musgrave, I; Seifert, R

    1996-01-01

    The Ca2+-ATPase inhibitor thapsigargin (TG) activates bivalent-cation early in human neutrophils via depletion of intracellular Ca2+ stores bu little is known about the underlying mechanism and the functional role of TG-induced cation entry. We studied the effects of TG on univalent- and bivalent cation entry, lysozyme release and superoxide-anion (O2-) formation in human neutrophils. TG, like the chemotactic peptide, N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP), stimulated entry of Ca2+, Mn2+, Ba2+, Sr2+ and Na+ in a 1-¿beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl¿-1H-imidazole hydrochloride (SK&F 96365)- and Gd3+-sensitive manner. The inhibitors of protein phosphates 1/2A, calyculin A and okadaic acid, diminished TG-induced cation influxes, whereas the inhibitors of protein phosphatase 2B, cyclosporin A and FK-506, were potentiators. Pertussis toxin (PTX) partially inhibited the effects of TG on Ca2+ and Mn2+ entry. TG and fMLP activated inward currents with a linear current-voltage relationship and a reversal potential at about 0 mV. TG activated lysozyme release and potentiated fMLP-induced O2- formation. TG-induced lysozyme release was inhibited by SK&F 96365, PTX and the removal of extracellular Ca2+ or Na+. Our data show that TG activates a non-selective and SK&F 96365- and Gd3+-sensitive cation entry pathway and is a partial secretagogue. TG-stimulated cation entry involves PTX-sensitive G-proteins and protein phosphatases, with protein phosphatases 1/2A and 2B playing opposite roles. PMID:8670085

  15. Bacteriophage Transduction in Staphylococcus epidermidis

    PubMed Central

    Olson, Michael E.; Horswill, Alexander R.

    2016-01-01

    The genetic manipulation of Staphylococcus epidermidis for molecular experimentation has long been an area of difficulty. Many of the traditional laboratory techniques for strain construction are laborious and hampered by poor efficiency. The ability to move chromosomal genetic markers and plasmids using bacteriophage transduction has greatly increased the speed and ease of S. epidermidis studies. These molecular genetic advances have advanced the S. epidermidis research field beyond a select few genetically tractable strains and facilitated investigations of clinically relevant isolates. PMID:24222465

  16. Bacteriophage Transduction in Staphylococcus aureus.

    PubMed

    Olson, Michael E

    2016-01-01

    The genetic manipulation of Staphylococcus aureus for molecular experimentation is a valuable tool for assessing gene function and virulence. Genetic variability between strains coupled with difficult laboratory techniques for strain construction is a frequent roadblock in S. aureus research. Bacteriophage transduction greatly increases the speed and ease of S. aureus studies by allowing movement of chromosomal markers and plasmids between strains. This technique enables the S. aureus research community to focus investigations on clinically relevant isolates.

  17. Generalized transduction in Rhizobium meliloti.

    PubMed

    Martin, M O; Long, S R

    1984-07-01

    Generalized transduction of Rhizobium meliloti 1021 was carried out by bacteriophage N3. Genetic markers on the chromosome and the pSym megaplasmid were transduced, along with markers on several IncP plasmids. Cotransduction between transposon Tn5 insertions and integrated recombinant plasmid markers permitted correlation of cotransductional frequencies and known physical distances. Bacteriophage N3 was capable of infecting several commonly used strains of R. meliloti.

  18. A membrane-free cation selective water-gated transistor.

    PubMed

    Althagafi, Talal M; Al Baroot, Abbad F; Algarni, Saud A; Grell, Martin

    2016-10-01

    Sensors for the detection of waterborne cations are of great practical interest, and chemistry has synthesised a formidable catalogue of cation selective complexation agents ('ionophores') as selective sensitisers. Current ionophore-based sensors separate the complexation of the cation by the ionophore, and the transduction of complexation into an electrical signal, into separate components. We here unite both functions into a single, sensitised semiconducting layer of a water-gated organic thin film transistor (OTFT). The resulting OTFT transduces waterborne cations into an electrical signal with same selectivity, sensitivity, and limit of detection as established sensors at much simplified preparation and operation. This opens a new route to apply the 'ionophore' family of functional organic materials in practical cation sensors.

  19. A membrane-free cation selective water-gated transistor.

    PubMed

    Althagafi, Talal M; Al Baroot, Abbad F; Algarni, Saud A; Grell, Martin

    2016-10-01

    Sensors for the detection of waterborne cations are of great practical interest, and chemistry has synthesised a formidable catalogue of cation selective complexation agents ('ionophores') as selective sensitisers. Current ionophore-based sensors separate the complexation of the cation by the ionophore, and the transduction of complexation into an electrical signal, into separate components. We here unite both functions into a single, sensitised semiconducting layer of a water-gated organic thin film transistor (OTFT). The resulting OTFT transduces waterborne cations into an electrical signal with same selectivity, sensitivity, and limit of detection as established sensors at much simplified preparation and operation. This opens a new route to apply the 'ionophore' family of functional organic materials in practical cation sensors. PMID:27433556

  20. Folate-targeted gadolinium-lipid-based nanoparticles as a bimodal contrast agent for tumor fluorescent and magnetic resonance imaging.

    PubMed

    Nakamura, Taro; Kawano, Kumi; Shiraishi, Kouichi; Yokoyama, Masayuki; Maitani, Yoshie

    2014-01-01

    To enhance tumor magnetic resonance imaging (MRI) signals via the selective accumulation of contrast agents, we prepared folate-modified gadolinium-lipid-based nanoparticles as MRI contrast agents. Folate-modified nanoparticles were comprised of polyethylene glycol (PEG)-lipid, gadolinium diethylenetriamine pentaacetic acid lipid, cationic cholesterol derivatives, folate-conjugated PEG-lipid, and Cy7-PEG-lipid. Folate receptor-mediated cellular nanoparticle association was examined in KB cells, which overexpress the folate receptor. The biodistribution of nanoparticles after their intravenous injection into KB tumor-bearing mice was measured. Mice were imaged through in vivo fluorescence imaging and MRI 24 h after nanoparticle injection, and the intensity enhancement of the tumor MRI signal was evaluated. Increased cellular association of folate-modified nanoparticles was inhibited by excess free folic acid, indicating that nanoparticle association was folate receptor-mediated. Irrespective of folate modification, the amount of nanoparticles in blood 24 h after injection was ca. 10% of the injected dose. Compared with non-modified nanoparticles, folate-modified nanoparticles exhibited significant accumulation in tumor tissues without altering other biodistribution, as well as enhanced tumor fluorescence and MRI signal intensity. The results support the feasibility of MRI- and in vivo fluorescence imaging-based tumor visualization using folate-modified nanoparticles and provide opportunities to develop folate targeting-based imaging applications.

  1. Assessing cellular toxicities in fibroblasts upon exposure to lipid-based nanoparticles: a high content analysis approach

    NASA Astrophysics Data System (ADS)

    Solmesky, Leonardo J.; Shuman, Michal; Goldsmith, Meir; Weil, Miguel; Peer, Dan

    2011-12-01

    Lipid-based nanoparticles (LNPs) are widely used for the delivery of drugs and nucleic acids. Although most of them are considered safe, there is confusing evidence in the literature regarding their potential cellular toxicities. Moreover, little is known about the recovery process cells undergo after a cytotoxic insult. We have previously studied the systemic effects of common LNPs with different surface charge (cationic, anionic, neutral) and revealed that positively charged LNPs ((+)LNPs) activate pro-inflammatory cytokines and induce interferon response by acting as an agonist of Toll-like receptor 4 on immune cells. In this study, we focused on the response of human fibroblasts exposed to LNPs and their cellular recovery process. To this end, we used image-based high content analysis (HCA). Using this strategy, we were able to show simultaneously, in several intracellular parameters, that fibroblasts can recover from the cytotoxic effects of (+)LNPs. The use of HCA opens new avenues in understanding cellular response and nanotoxicity and may become a valuable tool for screening safe materials for drug delivery and tissue engineering.

  2. ROS-dependent signal transduction

    PubMed Central

    Reczek, Colleen R; Chandel, Navdeep S

    2014-01-01

    Reactive oxygen species (ROS) are no longer viewed as just a toxic by-product of mitochondrial respiration, but are now appreciated for their role in regulating a myriad of cellular signaling pathways. H2O2, a type of ROS, is a signaling molecule that confers target specificity through thiol oxidation. Although redox-dependent signaling has been implicated in numerous cellular processes, the mechanism by which the ROS signal is transmitted to its target protein in the face of highly reactive and abundant antioxidants is not fully understood. In this review of redox-signaling biology, we discuss the possible mechanisms for H2O2-dependent signal transduction. PMID:25305438

  3. Meeting report: teaching signal transduction.

    PubMed

    Kramer, Ijsbrand; Thomas, Geraint

    2006-01-01

    In July, 2005, the European Institute of Chemistry and Biology at the campus of the University of Bordeaux, France, hosted a focused week of seminars, workshops, and discussions around the theme of "teaching signal transduction." The purpose of the summer school was to offer both junior and senior university instructors a chance to reflect on the development and delivery of their teaching activities in this area. This was achieved by combining open seminars with restricted access workshops and discussion events. The results suggest ways in which systems biology, information and communication technology, Web-based investigations, and high standard illustrations might be more effectively and efficiently incorporated into modern cell biology courses.

  4. Generalized Transduction in the Phytopathogen Pseudomonas syringae.

    PubMed

    Nordeen, R O; Currier, T C

    1983-06-01

    Bacteriophages isolated from culture supernatants of Pseudomonas syringae pv. syringae and from sewage transferred various chromosomal genes to P. syringae PS224. Linkage between arginine and tryptophan loci was demonstrated. The number of transductants recovered per milliliter was not altered appreciably by UV irradiation of selected phage isolates. In addition, the presence of the IncP2 plasmid R38 in a P. syringae PS224 arginine auxotroph did not increase the transduction frequency as it does in Pseudomonas aeruginosa. Increasing the multiplicity of infection of transducing phage Pssy15 from 1 to 10 resulted in up to a 10-fold increase in the number of transductants recovered, although the actual transductional frequency remained about the same. Treatment of transduction mixtures with DNase did not affect transductional frequency.

  5. Sensory Transduction in Caenorhabditis elegans

    NASA Astrophysics Data System (ADS)

    Brown, Austin L.; Ramot, Daniel; Goodman, Miriam B.

    The roundworm Caenorhabditis elegans has a well-defined and comparatively simple repertoire of sensory-guided behaviors, all of which rely on its ability to detect chemical, mechanical or thermal stimuli. In this chapter, we review what is known about the ion channels that mediate sensation in this remarkable model organism. Genetic screens for mutants defective in sensory-guided behaviors have identified genes encoding channel proteins, which are likely transducers of chemical, thermal, and mechanical stimuli. Such classical genetic approaches are now being coupled with molecular genetics and in vivo cellular physiology to elucidate how these channels are activated in specific sensory neurons. The ion channel superfamilies implicated in sensory transduction in C. elegans - CNG, TRP, and DEG/ENaC - are conserved across phyla and also appear to contribute to sensory transduction in other organisms, including vertebrates. What we learn about the role of these ion channels in C. elegans sensation is likely to illuminate analogous processes in other animals, including humans.

  6. Oxysterols and calcium signal transduction.

    PubMed

    Mackrill, John J

    2011-09-01

    Ionised calcium (Ca(2+)) is a key second messenger, regulating almost every cellular process from cell death to muscle contraction. Cytosolic levels of this ion can be increased via gating of channel proteins located in the plasma membrane, endoplasmic reticulum and other membrane-delimited organelles. Ca(2+) can be removed from cells by extrusion across the plasma membrane, uptake into organelles and buffering by anionic components. Ca(2+) channels and extrusion mechanisms work in concert to generate diverse spatiotemporal patterns of this second messenger, the distinct profiles of which determine different cellular outcomes. Increases in cytoplasmic Ca(2+) concentration are one of the most rapid cellular responses upon exposure to certain oxysterol congeners or to oxidised low-density lipoprotein, occurring within seconds of addition and preceding increases in levels of reactive oxygen species, or changes in gene expression. Furthermore, exposure of cells to oxysterols for periods of hours to days modulates Ca(2+) signal transduction, with these longer-term alterations in cellular Ca(2+) homeostasis potentially underlying pathological events within atherosclerotic lesions, such as hyporeactivity to vasoconstrictors observed in vascular smooth muscle, or ER stress-induced cell death in macrophages. Despite their candidate roles in physiology and disease, little is known about the molecular mechanisms that couple changes in oxysterol concentrations to alterations in Ca(2+) signalling. This review examines the ways in which oxysterols could influence Ca(2+) signal transduction and the potential roles of this in health and disease. PMID:21513705

  7. Providing lipid-based nutrient supplements does not affect developmental milestones among Malawian children

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our objective was to assess whether using lipid-based nutrient supplements (LNS) to complement the diets of infants and young children affected when they achieved selected developmental milestones. In rural Malawi, 840 6-month-old healthy infants were enrolled to a randomised trial. Control particip...

  8. Meeting Report: Teaching Signal Transduction

    PubMed Central

    Kramer, IJsbrand; Thomas, Geraint

    2006-01-01

    In July, 2005, the European Institute of Chemistry and Biology at the campus of the University of Bordeaux, France, hosted a focused week of seminars, workshops, and discussions around the theme of “teaching signal transduction.” The purpose of the summer school was to offer both junior and senior university instructors a chance to reflect on the development and delivery of their teaching activities in this area. This was achieved by combining open seminars with restricted access workshops and discussion events. The results suggest ways in which systems biology, information and communication technology, Web-based investigations, and high standard illustrations might be more effectively and efficiently incorporated into modern cell biology courses. PMID:17012185

  9. Vectofusin-1, a new viral entry enhancer, strongly promotes lentiviral transduction of human hematopoietic stem cells.

    PubMed

    Fenard, David; Ingrao, Dina; Seye, Ababacar; Buisset, Julien; Genries, Sandrine; Martin, Samia; Kichler, Antoine; Galy, Anne

    2013-05-07

    Gene transfer into hCD34(+) hematopoietic stem/progenitor cells (HSCs) using human immunodeficiency virus type 1 (HIV-1)-based lentiviral vectors (LVs) has several promising therapeutic applications. Yet, efficiency, safety, and cost of LV gene therapy could be ameliorated by enhancing target cell transduction levels and reducing the amount of LV used on the cells. Several transduction enhancers already exist such as fibronectin fragments and cationic compounds, but all present limitations. In this study, we describe a new transduction enhancer called Vectofusin-1, which is a short cationic peptide, active on several LV pseudotypes. Vectofusin-1 is used as a soluble additive to safely increase the frequency of transduced HSCs and to augment the level of transduction to one or two copies of vector per cell in a vector dose-dependent manner. Vectofusin-1 acts at the entry step by promoting the adhesion and the fusion between viral and cellular membranes. Vectofusin-1 is therefore a promising additive that could significantly ameliorate hCD34(+) cell-based gene therapy.Molecular Therapy-Nucleic Acids (2013) 2, e90; doi:10.1038/mtna.2013.17; published online 7 May 2013.

  10. Advanced drug delivery to the lymphatic system: lipid-based nanoformulations.

    PubMed

    Ali Khan, Arshad; Mudassir, Jahanzeb; Mohtar, Noratiqah; Darwis, Yusrida

    2013-01-01

    The delivery of drugs and bioactive compounds via the lymphatic system is complex and dependent on the physiological uniqueness of the system. The lymphatic route plays an important role in transporting extracellular fluid to maintain homeostasis and in transferring immune cells to injury sites, and is able to avoid first-pass metabolism, thus acting as a bypass route for compounds with lower bioavailability, ie, those undergoing more hepatic metabolism. The lymphatic route also provides an option for the delivery of therapeutic molecules, such as drugs to treat cancer and human immunodeficiency virus, which can travel through the lymphatic system. Lymphatic imaging is useful in evaluating disease states and treatment plans for progressive diseases of the lymph system. Novel lipid-based nanoformulations, such as solid lipid nanoparticles and nanostructured lipid carriers, have unique characteristics that make them promising candidates for lymphatic delivery. These formulations are superior to colloidal carrier systems because they have controlled release properties and provide better chemical stability for drug molecules. However, multiple factors regulate the lymphatic delivery of drugs. Prior to lymphatic uptake, lipid-based nanoformulations are required to undergo interstitial hindrance that modulates drug delivery. Therefore, uptake and distribution of lipid-based nanoformulations by the lymphatic system depends on factors such as particle size, surface charge, molecular weight, and hydrophobicity. Types of lipid and concentration of the emulsifier are also important factors affecting drug delivery via the lymphatic system. All of these factors can cause changes in intermolecular interactions between the lipid nanoparticle matrix and the incorporated drug, which in turn affects uptake of drug into the lymphatic system. Two lipid-based nanoformulations, ie, solid lipid nanoparticles and nanostructured lipid carriers, have been administered via multiple routes

  11. Advanced drug delivery to the lymphatic system: lipid-based nanoformulations

    PubMed Central

    Khan, Arshad Ali; Mudassir, Jahanzeb; Mohtar, Noratiqah; Darwis, Yusrida

    2013-01-01

    The delivery of drugs and bioactive compounds via the lymphatic system is complex and dependent on the physiological uniqueness of the system. The lymphatic route plays an important role in transporting extracellular fluid to maintain homeostasis and in transferring immune cells to injury sites, and is able to avoid first-pass metabolism, thus acting as a bypass route for compounds with lower bioavailability, ie, those undergoing more hepatic metabolism. The lymphatic route also provides an option for the delivery of therapeutic molecules, such as drugs to treat cancer and human immunodeficiency virus, which can travel through the lymphatic system. Lymphatic imaging is useful in evaluating disease states and treatment plans for progressive diseases of the lymph system. Novel lipid-based nanoformulations, such as solid lipid nanoparticles and nanostructured lipid carriers, have unique characteristics that make them promising candidates for lymphatic delivery. These formulations are superior to colloidal carrier systems because they have controlled release properties and provide better chemical stability for drug molecules. However, multiple factors regulate the lymphatic delivery of drugs. Prior to lymphatic uptake, lipid-based nanoformulations are required to undergo interstitial hindrance that modulates drug delivery. Therefore, uptake and distribution of lipid-based nanoformulations by the lymphatic system depends on factors such as particle size, surface charge, molecular weight, and hydrophobicity. Types of lipid and concentration of the emulsifier are also important factors affecting drug delivery via the lymphatic system. All of these factors can cause changes in intermolecular interactions between the lipid nanoparticle matrix and the incorporated drug, which in turn affects uptake of drug into the lymphatic system. Two lipid-based nanoformulations, ie, solid lipid nanoparticles and nanostructured lipid carriers, have been administered via multiple routes

  12. Sentra, a database of signal transduction proteins.

    SciTech Connect

    Maltsev, N.; Marland, E.; Yu, G. X.; Bhatnagar, S.; Lusk, R.; Mathematics and Computer Science

    2002-01-01

    Sentra (http://www-wit.mcs.anl.gov/sentra) is a database of signal transduction proteins with the emphasis on microbial signal transduction. The database was updated to include classes of signal transduction systems modulated by either phosphorylation or methylation reactions such as PAS proteins and serine/threonine kinases, as well as the classical two-component histidine kinases and methyl-accepting chemotaxis proteins. Currently, Sentra contains signal transduction proteins from 43 completely sequenced prokaryotic genomes as well as sequences from SWISS-PROT and TrEMBL. Signal transduction proteins are annotated with information describing conserved domains, paralogous and orthologous sequences, and conserved chromosomal gene clusters. The newly developed user interface supports flexible search capabilities and extensive visualization of the data.

  13. SENTRA, a database of signal transduction proteins.

    SciTech Connect

    D'Souza, M.; Romine, M. F.; Maltsev, N.; Mathematics and Computer Science; PNNL

    2000-01-01

    SENTRA, available via URL http://wit.mcs.anl.gov/WIT2/Sentra/, is a database of proteins associated with microbial signal transduction. The database currently includes the classical two-component signal transduction pathway proteins and methyl-accepting chemotaxis proteins, but will be expanded to also include other classes of signal transduction systems that are modulated by phosphorylation or methylation reactions. Although the majority of database entries are from prokaryotic systems, eukaroytic proteins with bacterial-like signal transduction domains are also included. Currently SENTRA contains signal transduction proteins in 34 complete and almost completely sequenced prokaryotic genomes, as well as sequences from 243 organisms available in public databases (SWISS-PROT and EMBL). The analysis was carried out within the framework of the WIT2 system, which is designed and implemented to support genetic sequence analysis and comparative analysis of sequenced genomes.

  14. The Physiology of Mechanoelectrical Transduction Channels in Hearing

    PubMed Central

    Fettiplace, Robert; Kim, Kyunghee X.

    2014-01-01

    Much is known about the mechanotransducer (MT) channels mediating transduction in hair cells of the vertrbrate inner ear. With the use of isolated preparations, it is experimentally feasible to deliver precise mechanical stimuli to individual cells and record the ensuing transducer currents. This approach has shown that small (1–100 nm) deflections of the hair-cell stereociliary bundle are transmitted via interciliary tip links to open MT channels at the tops of the stereocilia. These channels are cation-permeable with a high selectivity for Ca2+; two channels are thought to be localized at the lower end of the tip link, each with a large single-channel conductance that increases from the low- to high-frequency end of the cochlea. Ca2+ influx through open channels regulates their resting open probability, which may contribute to setting the hair cell resting potential in vivo. Ca2+ also controls transducer fast adaptation and force generation by the hair bundle, the two coupled processes increasing in speed from cochlear apex to base. The molecular intricacy of the stereocilary bundle and the transduction apparatus is reflected by the large number of single-gene mutations that are linked to sensorineural deafness, especially those in Usher syndrome. Studies of such mutants have led to the discovery of many of the molecules of the transduction complex, including the tip link and its attachments to the stereociliary core. However, the MT channel protein is still not firmly identified, nor is it known whether the channel is activated by force delivered through accessory proteins or by deformation of the lipid bilayer. PMID:24987009

  15. A Critical Review of Lipid-based Nanoparticles for Taxane Delivery

    PubMed Central

    Feng, Lan; Mumper, Russell J.

    2012-01-01

    Nano-based delivery systems have attracted a great deal of attention in the past two decades as a strategy to overcome the low therapeutic index of conventional anticancer drugs and delivery barriers in solid tumors. Myriads of preclinical studies have been focused on developing nano-based formulations to effectively deliver taxanes, one of the most important and most prescribed anticancer drug types in the clinic. Given the hydrophobic property of taxanes, lipid-based NPs, serve as a viable alternative delivery system. This critical review will provide an overview and perspective of the advancement of lipid-based nanoparticles for taxane delivery. Currently available formulations of taxanes and their drawbacks as well as criteria for idea taxane delivery system will be discussed. PMID:22796606

  16. Lipid-based carriers for pulmonary products: preclinical development and case studies in humans.

    PubMed

    Cipolla, David; Shekunov, Boris; Blanchard, Jim; Hickey, Anthony

    2014-08-01

    A number of lipid-based technologies have been applied to pharmaceuticals to modify their drug release characteristics, and additionally, to improve the drug loading for poorly soluble drugs. These technologies, including solid-state lipid microparticles, many of which are porous in nature, liposomes, solid lipid nanoparticles and nanostructured lipid carriers, are increasingly being developed for inhalation applications. This article provides a review of the rationale for the use of these technologies in the pulmonary delivery of drugs, and summarizes the manufacturing processes and their limitations, the in vitro and in vivo performance of these systems, the safety of these lipid-based systems in the lung, and their promise for commercialization. PMID:24819218

  17. Lipid-Based Nanoparticles as Pharmaceutical Drug Carriers: From Concepts to Clinic

    PubMed Central

    Puri, Anu; Loomis, Kristin; Smith, Brandon; Lee, Jae-Ho; Yavlovich, Amichai; Heldman, Eli; Blumenthal, Robert

    2010-01-01

    In recent years, various nanotechnology platforms in the area of medical biology, including both diagnostics and therapy, have gained remarkable attention. Moreover, research and development of engineered multifunctional nanoparticles as pharmaceutical drug carriers have spurred exponential growth in applications to medicine in the last decade. Design principles of these nanoparticles, including nano-emulsions, dendrimers, nano-gold, liposomes, drug-carrier conjugates, antibody-drug complexes, and magnetic nanoparticles, are primarily based on unique assemblies of synthetic, natural, or biological components, including but not limited to synthetic polymers, metal ions, oils, and lipids as their building blocks. However, the potential success of these particles in the clinic relies on consideration of important parameters such as nanoparticle fabrication strategies, their physical properties, drug loading efficiencies, drug release potential, and, most importantly, minimum toxicity of the carrier itself. Among these, lipid-based nanoparticles bear the advantage of being the least toxic for in vivo applications, and significant progress has been made in the area of DNA/RNA and drug delivery using lipid-based nanoassemblies. In this review, we will primarily focus on the recent advances and updates on lipid-based nanoparticles for their projected applications in drug delivery. We begin with a review of current activities in the field of liposomes (the so-called honorary nanoparticles), and challenging issues of targeting and triggering will be discussed in detail. We will further describe nanoparticles derived from a novel class of amphipathic lipids called bolaamphiphiles with unique lipid assembly features that have been recently examined as drug/DNA delivery vehicles. Finally, an overview of an emerging novel class of particles (based on lipid components other than phospholipids), solid lipid nanoparticles and nanostructured lipid carriers will be presented. We

  18. Lipid-based nanoparticles as pharmaceutical drug carriers: from concepts to clinic.

    PubMed

    Puri, Anu; Loomis, Kristin; Smith, Brandon; Lee, Jae-Ho; Yavlovich, Amichai; Heldman, Eliahu; Blumenthal, Robert

    2009-01-01

    In recent years, various nanotechnology platforms in the area of medical biology, including both diagnostics and therapy, have gained remarkable attention. Moreover, research and development of engineered multifunctional nanoparticles as pharmaceutical drug carriers have spurred exponential growth in applications to medicine in the last decade. Design principles of these nanoparticles, including nanoemulsions, dendrimers, nano-gold, liposomes, drug-carrier conjugates, antibody-drug complexes, and magnetic nanoparticles, are primarily based on unique assemblies of synthetic, natural, or biological components, including but not limited to synthetic polymers, metal ions, oils, and lipids as their building blocks. However, the potential success of these particles in the clinic relies on consideration of important parameters such as nanoparticle fabrication strategies, their physical properties, drug loading efficiencies, drug release potential, and, most importantly, minimum toxicity of the carrier itself. Among these, lipid-based nanoparticles bear the advantage of being the least toxic for in vivo applications, and significant progress has been made in the area of DNA/RNA and drug delivery using lipid-based nanoassemblies. In this review, we will primarily focus on the recent advances and updates on lipid-based nanoparticles for their projected applications in drug delivery. We begin with a review of current activities in the field of liposomes (the so-called honorary nanoparticles), and challenging issues of targeting and triggering will be discussed in detail. We will further describe nanoparticles derived from a novel class of amphipathic lipids called bolaamphiphiles with unique lipid assembly features that have been recently examined as drug/DNA delivery vehicles. Finally, an overview of an emerging novel class of particles (based on lipid components other than phospholipids), solid lipid nanoparticles and nanostructured lipid carriers will be presented. We

  19. Enhanced bioavailability of nerve growth factor with phytantriol lipid-based crystalline nanoparticles in cochlea

    PubMed Central

    Bu, Meng; Tang, Jingling; Wei, Yinghui; Sun, Yanhui; Wang, Xinyu; Wu, Linhua; Liu, Hongzhuo

    2015-01-01

    Purpose Supplementation of exogenous nerve growth factor (NGF) into the cochlea of deafened animals rescues spiral ganglion cells from degeneration. However, a safe and potent delivery of therapeutic proteins, such as NGF, to spiral ganglion cells remains one of the greatest challenges. This study presents the development of self-assembled cubic lipid-based crystalline nanoparticles to enhance inner ear bioavailability of bioactive NGF via a round window membrane route. Methods A novel nanocarrier-entrapped NGF was developed based on phytantriol by a liquid precursor dilution, with Pluronic® F127 and propylene glycol as the surfactant and solubilizer, respectively. Upon dilution of the liquid lipid precursors, monodispersed submicron-sized particles with a slight negative charge formed spontaneously. Results Biological activity of entrapped NGF was assessed using pheochromocytoma cells with NGF-loaded reservoirs to induce significant neuronal outgrowth, similar to that seen in free NGF-treated controls. Finally, a 3.28-fold increase in inner ear bioavailability was observed after administration of phytantriol lipid-based crystalline nanoparticles as compared to free drug, contributing to an enhanced drug permeability of the round window membrane. Conclusion Data presented here demonstrate the potential of lipid-based crystalline nanoparticles to improve the outcomes of patients bearing cochlear implants. PMID:26604754

  20. Gravitational Effects on Signal Transduction

    NASA Technical Reports Server (NTRS)

    Sytkowski, Arthur J.

    1999-01-01

    An understanding of the mechanisms by which individual cells perceive gravity and how these cells transduce and respond to gravitational stimuli is critical for the development of long-term manned space flight experiments. We now propose to use a well-characterized model erythroid cell system and to investigate gravitational perturbations of its erythropoietin (Epo) signaling pathway and gene regulation. Cells will be grown at 1-G and in simulated microgravity in the NASA Rotating Wall Vessel bioreactor (RWV). Cell growth and differentiation, the Epo-receptor, the protein kinase C pathway to the c-myc gene, and the protein phosphatase pathway to the c-myb gene will be studied and evaluated as reporters of gravitational stimuli. The results of these experiments will have impact on the problems of 1) gravitational sensing by individual cells, and 2) the anemia of space flight. This ground-based study also will serve as a Space Station Development Study in gravitational effects on intracellular signal transduction.

  1. Generalized transduction of small Yersinia enterocolitica plasmids.

    PubMed

    Hertwig, S; Popp, A; Freytag, B; Lurz, R; Appel, B

    1999-09-01

    To study phage-mediated gene transfer in Yersinia, the ability of Yersinia phages to transduce naturally occurring plasmids was investigated. The transduction experiments were performed with a temperate phage isolated from a pathogenic Yersinia enterocolitica strain and phage mixtures isolated from sewage. Small plasmids (4.3 and 5.8 kb) were transduced at a frequency of 10(-5) to 10(-7)/PFU. However, we could not detect the transduction of any indigenous virulence plasmid (ca. 72 kb) in pathogenic Yersinia strains. Transductants obtained by infection with the temperate phage were lysogenic and harbored the phage genome in their chromosomes.

  2. Recipient gene duplication during generalized transduction.

    PubMed

    Stodolsky, M

    1974-11-01

    An Hfr13 Delta(proA-lac) deletion recipient, -Delta(proA-lac)-F-purE(+)-, has been utilized in a study of the origins of duplications formed during chromosome fragment integration. Among the Pro(-)Lac(+) transductants, some have duplications spanning the F locus. These transductants are, or segregate, strains with F' episomes carrying genes of the duplication. Some of the duplications include purE(+), a gene which is not coinherited with lac(+) during bacteriophage P1-mediated transduction. Thus recipient genes have been duplicated during recombinant formation. Crossing-over models including replication steps provide a basis for explaining the duplication process.

  3. Considerations in developing lipid-based nutrient supplements for prevention of undernutrition: experience from the International Lipid-Based Nutrient Supplements (iLiNS) Project.

    PubMed

    Arimond, Mary; Zeilani, Mamane; Jungjohann, Svenja; Brown, Kenneth H; Ashorn, Per; Allen, Lindsay H; Dewey, Kathryn G

    2015-12-01

    The International Lipid-Based Nutrient Supplements (iLiNS) Project began in 2009 with the goal of contributing to the evidence base regarding the potential of lipid-based nutrient supplements (LNS) to prevent undernutrition in vulnerable populations. The first project objective was the development of acceptable LNS products for infants 6-24 months and for pregnant and lactating women, for use in studies in three countries (Burkina Faso, Ghana and Malawi). This paper shares the rationale for a series of decisions in supplement formulation and design, including those related to ration size, ingredients, nutrient content, safety and quality, and packaging. Most iLiNS supplements have a daily ration size of 20 g and are intended for home fortification of local diets. For infants, this ration size is designed to avoid displacement of breast milk and to allow for dietary diversity including any locally available and accessible nutrient-dense foods. Selection of ingredients depends on acceptability of flavour, micronutrient, anti-nutrient and essential fatty acid contents. The nutrient content of LNS designed to prevent undernutrition reflects the likelihood that in many resource-poor settings, diets of the most nutritionally vulnerable individuals (infants, young children, and pregnant and lactating women) are likely to be deficient in multiple micronutrients and, possibly, in essential fatty acids. During ingredient procurement and LNS production, safety and quality control procedures are required to prevent contamination with toxins or pathogens and to ensure that the product remains stable and palatable over time. Packaging design decisions must include consideration of product protection, stability, convenience and portion control.

  4. Considerations in developing lipid-based nutrient supplements for prevention of undernutrition: experience from the International Lipid-Based Nutrient Supplements (iLiNS) Project.

    PubMed

    Arimond, Mary; Zeilani, Mamane; Jungjohann, Svenja; Brown, Kenneth H; Ashorn, Per; Allen, Lindsay H; Dewey, Kathryn G

    2015-12-01

    The International Lipid-Based Nutrient Supplements (iLiNS) Project began in 2009 with the goal of contributing to the evidence base regarding the potential of lipid-based nutrient supplements (LNS) to prevent undernutrition in vulnerable populations. The first project objective was the development of acceptable LNS products for infants 6-24 months and for pregnant and lactating women, for use in studies in three countries (Burkina Faso, Ghana and Malawi). This paper shares the rationale for a series of decisions in supplement formulation and design, including those related to ration size, ingredients, nutrient content, safety and quality, and packaging. Most iLiNS supplements have a daily ration size of 20 g and are intended for home fortification of local diets. For infants, this ration size is designed to avoid displacement of breast milk and to allow for dietary diversity including any locally available and accessible nutrient-dense foods. Selection of ingredients depends on acceptability of flavour, micronutrient, anti-nutrient and essential fatty acid contents. The nutrient content of LNS designed to prevent undernutrition reflects the likelihood that in many resource-poor settings, diets of the most nutritionally vulnerable individuals (infants, young children, and pregnant and lactating women) are likely to be deficient in multiple micronutrients and, possibly, in essential fatty acids. During ingredient procurement and LNS production, safety and quality control procedures are required to prevent contamination with toxins or pathogens and to ensure that the product remains stable and palatable over time. Packaging design decisions must include consideration of product protection, stability, convenience and portion control. PMID:23647784

  5. Transduction of chemical into electrical energy.

    PubMed Central

    Nachmansohn, D

    1976-01-01

    The paper recalls some fundamental notions, developed by Otto Meyerhof, which were used in the analysis of the transduction of chemical into mechanical energy during muscular contraction. These notions formed the basis of the approach to the analysis of the transduction of chemical into electrical energy, i.e., the very principle underlying nerve and muscle excitability and bioelectricity. Instrumental for this purpose was the use, since 1937, of electric organs of fish, a tissue highly specialized for bioelectrogenesis. Images PMID:1061129

  6. Transduction of chemical into electrical energy.

    PubMed

    Nachmansohn, D

    1976-01-01

    The paper recalls some fundamental notions, developed by Otto Meyerhof, which were used in the analysis of the transduction of chemical into mechanical energy during muscular contraction. These notions formed the basis of the approach to the analysis of the transduction of chemical into electrical energy, i.e., the very principle underlying nerve and muscle excitability and bioelectricity. Instrumental for this purpose was the use, since 1937, of electric organs of fish, a tissue highly specialized for bioelectrogenesis.

  7. Multivariate analysis of physicochemical characteristics of lipid based nanoemulsifying cilostazol--quality by design.

    PubMed

    Pund, Swati; Shete, Yogesh; Jagadale, Sujata

    2014-03-01

    Simultaneous analysis of the effect of multiple formulation ingredients on the critical physico-chemical properties of lipid based nanoemulsifying cilostazol was studied using integrated quality by design approach. Cilostazol is a poorly soluble drug belonging to class II of the biopharmaceutics classification system. To improve the solubility and in turn bioavailability of cilostazol, a lipid based nanoemulsifying cilostazol was developed. Self nanoemulsifying system comprising of Capmul MCM (oily solubilizer), Tween 80 (surfactant); and Transcutol HP (cosolvent) was developed. A 2(3) full factorial experimental design was employed to optimize simultaneously the effect of levels of these three components on physico-chemical responses (viz. globule size, span, zeta potential, solubility, and dissolution efficiency at 30 min) of nanoemulsifying cilostazol. Graphical analysis using Pareto charts and Bayesian analysis along with mathematical modelling of the results allowed the identification and quantification of the formulation variables active on the selected responses. A polynomial equation fitted to the data was used to predict the composition with optimum responses. The optimum formulation was a mixture of Capmul MCM, Tween 80 and Transcutol HP; 3:5:5 parts by weight. Optimized composition on dilution with water showed globule size; 215.2 nm with a span of 0.42. The nanoemulsifying formulation showed equilibrium solubility and dissolution efficiency; 9.82 mg/ml and 83.3% respectively, indicating significant improvement in comparison to pristine cilostazol. Interaction between oil and the cosolvent significantly affected the globule size and the span of the resultant nanoemulsion. Zeta potential was independent of selected formulation variables. The optimized formulation was adsorbed onto Neusilin US2 without affecting nanoemusifying ability of lipid based cilostazol composition.

  8. Multivariate analysis of physicochemical characteristics of lipid based nanoemulsifying cilostazol--quality by design.

    PubMed

    Pund, Swati; Shete, Yogesh; Jagadale, Sujata

    2014-03-01

    Simultaneous analysis of the effect of multiple formulation ingredients on the critical physico-chemical properties of lipid based nanoemulsifying cilostazol was studied using integrated quality by design approach. Cilostazol is a poorly soluble drug belonging to class II of the biopharmaceutics classification system. To improve the solubility and in turn bioavailability of cilostazol, a lipid based nanoemulsifying cilostazol was developed. Self nanoemulsifying system comprising of Capmul MCM (oily solubilizer), Tween 80 (surfactant); and Transcutol HP (cosolvent) was developed. A 2(3) full factorial experimental design was employed to optimize simultaneously the effect of levels of these three components on physico-chemical responses (viz. globule size, span, zeta potential, solubility, and dissolution efficiency at 30 min) of nanoemulsifying cilostazol. Graphical analysis using Pareto charts and Bayesian analysis along with mathematical modelling of the results allowed the identification and quantification of the formulation variables active on the selected responses. A polynomial equation fitted to the data was used to predict the composition with optimum responses. The optimum formulation was a mixture of Capmul MCM, Tween 80 and Transcutol HP; 3:5:5 parts by weight. Optimized composition on dilution with water showed globule size; 215.2 nm with a span of 0.42. The nanoemulsifying formulation showed equilibrium solubility and dissolution efficiency; 9.82 mg/ml and 83.3% respectively, indicating significant improvement in comparison to pristine cilostazol. Interaction between oil and the cosolvent significantly affected the globule size and the span of the resultant nanoemulsion. Zeta potential was independent of selected formulation variables. The optimized formulation was adsorbed onto Neusilin US2 without affecting nanoemusifying ability of lipid based cilostazol composition. PMID:24316585

  9. Regulation of Cation Balance in Saccharomyces cerevisiae

    PubMed Central

    Cyert, Martha S.; Philpott, Caroline C.

    2013-01-01

    All living organisms require nutrient minerals for growth and have developed mechanisms to acquire, utilize, and store nutrient minerals effectively. In the aqueous cellular environment, these elements exist as charged ions that, together with protons and hydroxide ions, facilitate biochemical reactions and establish the electrochemical gradients across membranes that drive cellular processes such as transport and ATP synthesis. Metal ions serve as essential enzyme cofactors and perform both structural and signaling roles within cells. However, because these ions can also be toxic, cells have developed sophisticated homeostatic mechanisms to regulate their levels and avoid toxicity. Studies in Saccharomyces cerevisiae have characterized many of the gene products and processes responsible for acquiring, utilizing, storing, and regulating levels of these ions. Findings in this model organism have often allowed the corresponding machinery in humans to be identified and have provided insights into diseases that result from defects in ion homeostasis. This review summarizes our current understanding of how cation balance is achieved and modulated in baker’s yeast. Control of intracellular pH is discussed, as well as uptake, storage, and efflux mechanisms for the alkali metal cations, Na+ and K+, the divalent cations, Ca2+ and Mg2+, and the trace metal ions, Fe2+, Zn2+, Cu2+, and Mn2+. Signal transduction pathways that are regulated by pH and Ca2+ are reviewed, as well as the mechanisms that allow cells to maintain appropriate intracellular cation concentrations when challenged by extreme conditions, i.e., either limited availability or toxic levels in the environment. PMID:23463800

  10. Meeting report: Signal transduction meets systems biology

    PubMed Central

    2012-01-01

    In the 21st century, systems-wide analyses of biological processes are getting more and more realistic. Especially for the in depth analysis of signal transduction pathways and networks, various approaches of systems biology are now successfully used. The EU FP7 large integrated project SYBILLA (Systems Biology of T-cell Activation in Health and Disease) coordinates such an endeavor. By using a combination of experimental data sets and computational modelling, the consortium strives for gaining a detailed and mechanistic understanding of signal transduction processes that govern T-cell activation. In order to foster the interaction between systems biologists and experimentally working groups, SYBILLA co-organized the 15th meeting “Signal Transduction: Receptors, Mediators and Genes” together with the Signal Transduction Society (STS). Thus, the annual STS conference, held from November 7 to 9, 2011 in Weimar, Germany, provided an interdisciplinary forum for research on signal transduction with a major focus on systems biology addressing signalling events in T-cells. Here we report on a selection of ongoing projects of SYBILLA and how they were discussed at this interdisciplinary conference. PMID:22546078

  11. Lipid-based siRNA Delivery Systems: Challenges, Promises and Solutions Along the Long Journey.

    PubMed

    Sarisozen, Can; Salzano, Giuseppina; Torchilin, Vladimir P

    2016-01-01

    RNA interference (RNAi) is an evolutionary conserved highly specific gene-silencing mechanism initiated by small interfering RNA (siRNA) molecules. Fast-paced preclinical and clinical studies helped the siRNA technology become an efficient tool for undruggable targets in different diseases including genetic diseases, viral diseases and cancer. Despite great feature of siRNAs that can down-regulate any protein in the cells, the full potential and the success of the preclinical studies could not be translated into largely successful clinical outcomes. It has become clear that the possibility of overcoming the pitfalls for in vivo siRNA therapy fully depends on delivery systems. In this review, we start with the challenges and barriers for in vivo siRNA delivery. Then we briefly discuss the recent developments in siRNA modification technology. We specifically focused on siRNA lipidation and delivery approaches with special emphasis on the lipid based hybrid systems. Here we summarize the journey of lipid-based micelle-like nanoparticle systems that combine longevity in blood, effective cellular uptake and endosomal escape for successful siRNA delivery and discuss the multifunctional stimuli-sensitive systems based on lipids as the next generation smart systems. PMID:27033509

  12. Clinical studies with oral lipid based formulations of poorly soluble compounds

    PubMed Central

    Fatouros, Dimitrios G; Karpf, Ditte M; Nielsen, Flemming S; Mullertz, Anette

    2007-01-01

    This work is an attempt to give an overview of the clinical data available on lipid based formulations. Lipid and surfactant based formulations are recognized as a feasible approach to improve bioavailability of poorly soluble compounds. However not many clinical studies have been published so far. Several drug products intended for oral administration have been marketed utilizing lipid and surfactant based formulations. Sandimmune® and Sandimmune Neoral® (cyclosporin A, Novartis), Norvir® (ritonavir), and Fortovase® (saquinavir) have been formulated in self-emulsifying drug delivery systems (SEDDS). This review summarizes published pharmacokinetic studies of orally administered lipid based formulations of poorly aqueous soluble drugs in human subjects. Special attention has been paid to the physicochemical characteristics of the formulations, when available and the impact of these properties on the in vivo performance of the formulation. Equally important is the effect of concurrent food intake on the bioavailability of poorly soluble compounds. The effect of food on the bioavailability of compounds formulated in lipid and surfactant based formulations is also reviewed. PMID:18472981

  13. Oxidants as stimulators of signal transduction.

    PubMed

    Suzuki, Y J; Forman, H J; Sevanian, A

    1997-01-01

    Redox (oxidation-reduction) reactions regulate signal transduction. Oxidants such as superoxide, hydrogen peroxide, hydroxyl radicals, and lipid hydroperoxides (i.e., reactive oxygen species) are now realized as signaling molecules under subtoxic conditions. Nitric oxide is also an example of a redox mediator. Reactive oxygen species induce various biological processes such as gene expression by stimulating signal transduction components such as Ca(2+)-signaling and protein phosphorylation. Various oxidants increase cytosolic Ca2+; however, the exact origin of Ca2+ is controversial. Ca2+ may be released from the endoplasmic reticulum, extracellular space, or mitochondria in response to oxidant-influence on Ca2+ pumps, channels, and transporters. Alternatively, oxidants may release Ca2+ from Ca2+ binding proteins. Various oxidants stimulate tyrosine as well as serine/threonine phosphorylation, and direct stimulation of protein kinases and inhibition of protein phosphatases by oxidants have been proposed as mechanisms. The oxidant-stimulation of the effector molecules such as phospholipase A2 as well as the activation of oxidative stress-responsive transcription factors may also depend on the oxidant-mediated activation of Ca(2+)-signaling and/or protein phosphorylation. In addition to the stimulation of signal transduction by oxidants, the observations that ligand-receptor interactions produce reactive oxygen species and that antioxidants block receptor-mediated signal transduction led to a proposal that reactive oxygen species may be second messengers for transcription factor activation, apoptosis, bone resorption, cell growth, and chemotaxis. Physiological significance of the role of biological oxidants in the regulation of signal transduction as well as the mechanisms of the oxidant-stimulation of signal transduction are discussed.

  14. Probing visual transduction in a plant cell

    PubMed Central

    Uhl, Rainer; Hegemann, Peter

    1990-01-01

    Light scattering studies of vertebrate rod cells have greatly aided our understanding of the visual transduction process. This technique has now been successfully applied to study visual transduction in a unicellular alga. Flash-induced light scattering changes have been recorded which are repeatable, graded with photon exposure, and adaptive. They appear on a timescale of 15-1,000 ms and correlate kinetically with flash-induced movement responses. The responsible photoreceptor is a rhodopsin. Evidence is provided for the ability of the organism to count single photons. PMID:19431775

  15. Pathway to the piezoelectronic transduction logic device.

    PubMed

    Solomon, P M; Bryce, B A; Kuroda, M A; Keech, R; Shetty, S; Shaw, T M; Copel, M; Hung, L-W; Schrott, A G; Armstrong, C; Gordon, M S; Reuter, K B; Theis, T N; Haensch, W; Rossnagel, S M; Miyazoe, H; Elmegreen, B G; Liu, X-H; Trolier-McKinstry, S; Martyna, G J; Newns, D M

    2015-04-01

    The piezoelectronic transistor (PET) has been proposed as a transduction device not subject to the voltage limits of field-effect transistors. The PET transduces voltage to stress, activating a facile insulator-metal transition, thereby achieving multigigahertz switching speeds, as predicted by modeling, at lower power than the comparable generation field effect transistor (FET). Here, the fabrication and measurement of the first physical PET devices are reported, showing both on/off switching and cycling. The results demonstrate the realization of a stress-based transduction principle, representing the early steps on a developmental pathway to PET technology with potential to contribute to the IT industry.

  16. Macrophage-Specific Lipid-Based Nanoparticles Improve MRI Detection and Characterization of Human Atherosclerosis

    PubMed Central

    Lipinski, Michael J.; Frias, Juan C.; Amirbekian, Vardan; Briley-Saebo, Karen C.; Mani, Venkatesh; Samber, Daniel; Abbate, Antonio; Aguinaldo, Juan Gilberto S.; Massey, Davis; Fuster, Valentin; Vetrovec, George W.; Fayad, Zahi A.

    2009-01-01

    Objectives We sought to determine if gadolinium (Gd)-containing lipid-based nanoparticles (NPs) targeting the macrophage scavenger receptor-B (CD36) improve magnetic resonance (MR) detection and characterization of human atherosclerosis. Background The ability to detect atherosclerosis with MR imaging using gadolinium Gd-containing lipid-based NPs targeting macrophages may enable early detection of high-risk lesions prior to an atherothrombotic event. Gd-containing lipid-based NPs targeting macrophages improved MR detection of murine atherosclerosis. Methods Gd-containing NPs, anti-CD36 NPs and Fc-NPs were created. Macrophages were incubated with fluorescent targeted and non-targeted NPs to determine uptake via confocal microscopy and inductively coupled plasma mass spectroscopy (ICP-MS) quatified Gd uptake. Human aortic specimens were harvested at autopsy. Using a 1.5 T scanner, T1, T2, and PDW 3-dimensional scans were performed along with post-contrast scans after 24 h incubation. T1 and cluster analysis were performed and compared with immunohistopathology. Results The NPs had a mean diameter of 125 nm, 14,900 Gd-ions, and relaxivity was 37 mM-1s-1 at 1.5T and 37°C. Confocal microscopy and ICP-MS demonstrated significant in vitro macrophage uptake of targeted NPs while non-targeted NPs had minimal uptake. On T1 imaging, targeted NPs increased CNR by 52.5% which was significantly great than Fc-NPs (CNR increased 17.2%) and non-targeted NPs (CNR increased 18.7%) (p=0.001). Confocal fluorescent microscopy showed that NPs target resident macrophages while the untargeted NPs and Fc-NPs are found diffusely throughout the plaque. Targeted NPs had a greater signal intensity increase in the fibrous cap compared with (p<0.001) while non-targeted NPs and Fc-NPs had a greater increase in the lipid core (p<0.01). Conclusion Macrophage-specific (CD36) NPs bind human macrophages and improved MR detection and characterization of human aortic atherosclerosis. Thus, macrophage

  17. Lipid-based colloidal carriers for peptide and protein delivery – liposomes versus lipid nanoparticles

    PubMed Central

    Martins, Susana; Sarmento, Bruno; Ferreira, Domingos C; Souto, Eliana B

    2007-01-01

    This paper highlights the importance of lipid-based colloidal carriers and their pharmaceutical implications in the delivery of peptides and proteins for oral and parenteral administration. There are several examples of biomacromolecules used nowadays in the therapeutics, which are promising candidates to be delivered by means of liposomes and lipid nanoparticles, such as solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC). Several production procedures can be applied to achieve a high association efficiency between the bioactives and the carrier, depending on the physicochemical properties of both, as well as on the production procedure applied. Generally, this can lead to improved bioavailability, or in case of oral administration a more consistent temporal profile of absorption from the gastrointestinal tract. Advantages and drawbacks of such colloidal carriers are also pointed out. This article describes strategies used for formulation of peptides and proteins, methods used for assessment of association efficiency and practical considerations regarding the toxicological concerns. PMID:18203427

  18. Lipid-based colloidal carriers for peptide and protein delivery--liposomes versus lipid nanoparticles.

    PubMed

    Martins, Susana; Sarmento, Bruno; Ferreira, Domingos C; Souto, Eliana B

    2007-01-01

    This paper highlights the importance of lipid-based colloidal carriers and their pharmaceutical implications in the delivery of peptides and proteins for oral and parenteral administration. There are several examples of biomacromolecules used nowadays in the therapeutics, which are promising candidates to be delivered by means of liposomes and lipid nanoparticles, such as solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC). Several production procedures can be applied to achieve a high association efficiency between the bioactives and the carrier, depending on the physicochemical properties of both, as well as on the production procedure applied. Generally, this can lead to improved bioavailability, or in case of oral administration a more consistent temporal profile of absorption from the gastrointestinal tract. Advantages and drawbacks of such colloidal carriers are also pointed out. This article describes strategies used for formulation of peptides and proteins, methods used for assessment of association efficiency and practical considerations regarding the toxicological concerns. PMID:18203427

  19. Novel aliphatic lipid-based diesters for use in lubricant formulations: Structure property investigations

    NASA Astrophysics Data System (ADS)

    Raghunanan, Latchmi Cindy

    Structure-property relationships are increasingly valued for the identification of specifically engineered materials with properties optimized for targeted application(s). In this work, linear and branched diesters for use in lubricant formulations are prepared from lipid-based oleochemicals and their structure-property relationships reported. It is shown that the branched diesters possess exceptional physical property profiles, including suppression of crystallization, and are superior alternatives for use in lubricant formulations. For the linear aliphatic diesters, both high and low temperature properties were predictable functions of total chain length, and both were differently influenced by the fatty acid versus diol chain length. Symmetry did not influence either, although thermal stability decreased and thermal transition temperatures increased with increasing saturation. All of the linear diesters demonstrated Newtonian flow behaviour. Viscosity was also predictable as a function of total chain length; any microstructural features due to structural effects were superseded by mass effects.

  20. LIPID ABNORMALITIES AND LIPID-BASED REPAIR STRATEGIES IN ATOPIC DERMATITIS

    PubMed Central

    Elias, Peter M.

    2013-01-01

    Prior studies have revealed the key roles played by Th1/Th2 cell dysregulation, IgE production, mast cell hyperactivity, and dendritic cell signaling in the evolution of the chronic, pruritic, inflammatory dermatosis that characterizes atopic dermatitis (AD). We review here increasing evidence that the inflammation in AD results primarily from inherited abnormalities in epidermal structural and enzymatic proteins that impact permeability barrier function. We also will show that the barrier defect can be attributed to a paracellular abnormality due to a variety of abnormalities in lipid composition, transport and extracellular organization. Accordingly, we also review the therapeutic implications of this emerging pathogenic paradigm, including several current and potentially novel, lipid-based approaches to corrective therapy. PMID:24128970

  1. Super-cooled and amorphous lipid-based colloidal dispersions for the delivery of phytosterols.

    PubMed

    Ribeiro, H S; Gupta, R; Smith, K W; van Malssen, K F; Popp, A K; Velikov, K P

    2016-07-01

    Super-cooled and amorphous lipid-based colloids are highly desirable delivery systems because of their ability to encapsulate compounds in a soluble or in a non-crystalline state. In this study, we demonstrate the preparation and characterization of super-cooled and amorphous lipid-based nanoscale colloidal dispersions containing high concentrations of phytosterols (PSs). PSs are highly hydrophobic natural bioactive compounds that are known to significantly reduce blood cholesterol levels in humans, but are insoluble in water and are poorly soluble in common lipids such as triacylglycerols (TAGs). Using the ultrahigh pressure homogenization of pre-heated dispersions, followed by temperature quenching, colloidal dispersions with varying concentrations of PSs in the lipid phase are prepared. Long and medium chain TAGs in combination with a non-ionic surfactant are used. The particle size, morphology and stability are analysed by dynamic and static light scattering, electron microscopy, and X-ray diffraction. Rapid temperature quenching enables the formation of stable colloidal dispersions of 10 wt% PSs, more than five times the equilibrium solubility at room temperature. Super-cooled emulsions are formed using liquid TAG, whereas amorphous particles are formed in the case of solid TAG. In both cases, the complete suppression of the crystallization of both PSs and lipids is observed due to the nanoscale confinement. The colloidal dispersions are stable for at least four months. The insights of this work will help understand the colloid formation and particle morphology control in the development of delivery systems for hydrophobic bio-actives such as drugs, cosmeceuticals, nutraceuticals, nutritional and agricultural nanoscale formulations. PMID:27174457

  2. The design of cationic lipids for gene delivery.

    PubMed

    Martin, B; Sainlos, M; Aissaoui, A; Oudrhiri, N; Hauchecorne, M; Vigneron, J-P; Lehn, J-M; Lehn, P

    2005-01-01

    Synthetic gene delivery vectors are gaining increasing importance in gene therapy as an alternative to recombinant viruses. Among the various types of non-viral vectors, cationic lipids are especially attractive as they can be prepared with relative ease and extensively characterised. Further, each of their constituent parts can be modified, thereby facilitating the elucidation of structure-activity relationships. In this forward-looking review, cationic lipid-mediated gene delivery will mainly be discussed in terms of the structure of the three basic constituent parts of any cationic lipid: the polar headgroup, hydrophobic moiety and linker. Particular emphasis will be placed on recent advances in the field as well as on our own original contributions. In addition to reviewing critical physicochemical features (such as headgroup hydration) of monovalent lipids, the use of headgroups with known nucleic-acid binding modes, such as linear and branched polyamines, aminoglycosides and guanidinium functions, will be comprehensively assessed. A particularly exciting innovation in linker design is the incorporation of environment-sensitive groups, the intracellular hydrolysis of which may lead to more controlled DNA delivery. Examples of pH-, redox- and enzyme-sensitive functional groups integrated into the linker are highlighted and the benefits of such degradable vectors can be evaluated in terms of transfection efficiency and cationic lipid-associated cytotoxicity. Finally, possible correlations between the length and type of hydrophobic moiety and transfection efficiency will be discussed. In conclusion it may be foreseen that in order to be successful, the future of cationic lipid-based gene delivery will probably require the development of sophisticated virus-like systems, which can be viewed as "programmed supramolecular systems" incorporating the various functions required to perform in a chronological order the different steps involved in gene transfection.

  3. Advances in Targeting Signal Transduction Pathways

    PubMed Central

    McCubrey, James A.; Steelman, Linda S.; Chappell, William H.; Sun, Lin; Davis, Nicole M.; Abrams, Stephen L.; Franklin, Richard A.; Cocco, Lucio; Evangelisti, Camilla; Chiarini, Francesca; Martelli, Alberto M.; Libra, Massimo; Candido, Saverio; Ligresti, Giovanni; Malaponte, Grazia; Mazzarino, Maria C.; Fagone, Paolo; Donia, Marco; Nicoletti, Ferdinando; Polesel, Jerry; Talamini, Renato; Bäsecke, Jörg; Mijatovic, Sanja; Maksimovic-Ivanic, Danijela; Milella, Michele; Tafuri, Agostino; Dulińska-Litewka, Joanna; Laidler, Piotr; D'Assoro, Antonio B.; Drobot, Lyudmyla; Umezawa, Kazuo; Montalto, Giuseppe; Cervello, Melchiorre; Demidenko, Zoya N.

    2012-01-01

    Over the past few years, significant advances have occurred in both our understanding of the complexity of signal transduction pathways as well as the isolation of specific inhibitors which target key components in those pathways. Furthermore critical information is being accrued regarding how genetic mutations can affect the sensitivity of various types of patients to targeted therapy. Finally, genetic mechanisms responsible for the development of resistance after targeted therapy are being discovered which may allow the creation of alternative therapies to overcome resistance. This review will discuss some of the highlights over the past few years on the roles of key signaling pathways in various diseases, the targeting of signal transduction pathways and the genetic mechanisms governing sensitivity and resistance to targeted therapies. PMID:23455493

  4. The ethylene signal transduction pathway in Arabidopsis

    NASA Technical Reports Server (NTRS)

    Kieber, J. J.; Evans, M. L. (Principal Investigator)

    1997-01-01

    The gaseous hormone ethylene is an important regulator of plant growth and development. Using a simple response of etiolated seedlings to ethylene as a genetic screen, genes involved in ethylene signal transduction have been identified in Arabidopsis. Analysis of two of these genes that have been cloned reveals that ethylene signalling involves a combination of a protein (ETR1) with similarity to bacterial histidine kinases and a protein (CTR1) with similarity to Raf-1, a protein kinase involved in multiple signalling cascades in eukaryotic cells. Several lines of investigation provide compelling evidence that ETR1 encodes an ethylene receptor. For the first time there is a glimpse of the molecular circuitry underlying the signal transduction pathway for a plant hormone.

  5. Aging of signal transduction pathways, and pathology

    PubMed Central

    Carlson, Morgan E.; Silva, Haroldo S.; Conboy, Irina M.

    2008-01-01

    The major cell signaling pathways, and their specific mechanisms of transduction, have been a subject of investigation for many years. As our understanding of these pathways advances, we find that they are evolutionarily well-conserved not only individually, but also at the level of their crosstalk and signal integration. Productive interactions within the key signal transduction networks determine success in embryonic organogenesis, and postnatal tissue repair throughout adulthood. However, aside from clues revealed through examining age-related degenerative diseases, much remains uncertain about imbalances within these pathways during normal aging. Further, little is known about the molecular mechanisms by which alterations in the major cell signal transduction networks cause age-related pathologies. The aim of this review is to describe the complex interplay between the Notch, TGFβ, WNT, RTK-Ras and Hh signaling pathways, with a specific focus on the changes introduced within these networks by the aging process, and those typical of age-associated human pathologies. PMID:18474281

  6. Signal transduction in T lymphocytes in microgravity

    NASA Technical Reports Server (NTRS)

    Cogoli, A.

    1997-01-01

    More than 120 experiments conducted in space in the last 15 years have shown that dramatic changes are occurring in several types of single cells during their exposure to microgravity. One focus of today's research on cells in space is on signal transduction, especially those steps involving the cytoskeleton and cell-cell interactions. Signal transduction is often altered in microgravity as well as in hypergravity. This leads to changes in cell proliferation, genetic expression and differentiation. Interesting examples are leukocytes, HeLa cells, epidermoid cells and osteoblastic cells. Signalling pathways were studied in T lymphocytes in microgravity by several investigators after the discovery that mitogenic activation in vitro is virtually nil at 0g. T cells are a good model to study signal transduction because three extracellular signals (mitogen, IL-1 and IL-2) are required for full activation, and two classical pathways (via proteins G and PKC) are activated within the cell. In addition, low molecular weight GTP-binding proteins (Ras and Rap) are interacting with the cytoskeleton. The data at 0g support the notion that the expression of IL-2 receptor is inhibited at 0g, while mitogen binding and the transmission of IL-1 by accessory cells occur normally. In addition, alterations of the cytoskeleton suggest that the interaction with Rap proteins is disturbed. Data obtained with phorbol esters indicate that the function of PKC is changed in microgravity. Similar conclusions are drawn from the results with epidermoid cells A431.

  7. A novel lipid-based nanomicelle of docetaxel: evaluation of antitumor activity and biodistribution

    PubMed Central

    Ma, Mingshu; Hao, Yanli; Liu, Nan; Yin, Zhe; Wang, Lan; Liang, Xingjie; Zhang, Xiaoning

    2012-01-01

    Purpose A lipid-based, nanomicelle-loaded docetaxel (M-DOC) was designed and characterized. Optical imaging was employed to evaluate the pharmacokinetics and antitumor efficacy of docetaxel in vivo. Materials and methods The M-DOC was prepared using the emulsion-diffusion method. Transmission electron microscopy and dynamic light scattering were used to assess the morphology and particle size of the M-DOC. Critical micelle concentrations, their stability under physiological conditions, and their encapsulation efficiency – as measured by high-performance liquid chromatography – were assessed. Pharmacological features were evaluated in two different animal models by comparing M-DOC treatments with docetaxel injections (I-DOC). Bioluminescence imaging was used to assess antitumor activity and docetaxel distribution in vivo, using nude mice injected with luciferase-expressing MDA-MB-231 human breast tumor cells. In addition, animals injected with B16 melanoma cells were used to measure survival time and docetaxel distribution. Results The M-DOC was prepared as round, uniform spheres with an effective diameter of 20.8 nm. The critical micelle concentration of the original emulsion was 0.06%. Satisfactory encapsulation efficiency (87.6% ± 3.0%) and 12-hour stability were achieved. Xenograft results demonstrated that the M-DOC was more effective in inhibiting tumor growth, without significantly changing body weight. Survival was prolonged by 12.6% in the M-DOC group. Tumor growth inhibitory rates in the M-DOC and I-DOC groups were 91.2% and 57.8% in volume and 71.8% and 44.9% in weight, respectively. Optical bioluminescence imaging of tumor growths yielded similar results. Area under the curve(0–6 hour) levels of docetaxel in blood and tumors were significantly higher in the M-DOC group (15.9 ± 3.2 μg/mL−1, 601.1 ± 194.5 μg/g−1) than in the I-DOC group (7.2 ± 1.7 μg/mL−1, 357.8 ± 86.2 μg/g−1). The fluorescent dye 1,1-dioctadecyl-3,3,3,3

  8. Generalized transduction Of shigella flexneri by converting phage PE5.

    PubMed

    Financsek, I; Kétyi, I

    1976-01-01

    Phage PE5, responsible for the conversion of type V antigen in Shigella flexneri, has the ability to produce generalized transduction. The correlation between phage multiplicity and the number of transductants, the specific inhibitory activity of anti-PE5 serum, and the lack of transduction in PE5 resistant recipients, indicate the role of phage PE5 in generalized transduction. Transduction of the R100-1 factor resulted in a non-transmissible tetracycline resistance segragation. The characteristics of the tetracycline resistance determinant suggest the possibility of integration.

  9. Cesium cation affinities and basicities

    NASA Astrophysics Data System (ADS)

    Gal, Jean-François; Maria, Pierre-Charles; Massi, Lionel; Mayeux, Charly; Burk, Peeter; Tammiku-Taul, Jaana

    2007-11-01

    This review focuses on the quantitative data related to cesium cation interaction with neutral or negatively charged ligands. The techniques used for measuring the cesium cation affinity (enthalpies, CCA), and cesium cation basicities (Gibbs free energies, CCB) are briefly described. The quantum chemical calculations methods that were specifically designed for the determination of cesium cation adduct structures and the energetic aspects of the interaction are discussed. The experimental results, obtained essentially from mass spectrometry techniques, and complemented by thermochemical data, are tabulated and commented. In particular, the correlations between cesium cation affinities and lithium cation affinities for the various kinds of ligands (rare gases, polyatomic neutral molecules, among them aromatic compounds and negative ions) serve as a basis for the interpretation of the diverse electrostatic modes of interaction. A brief account of some recent analytical applications of ion/molecule reactions with Cs+, as well as other cationization approaches by Cs+, is given.

  10. Formulation and in vitro characterization of a novel solid lipid-based drug delivery system.

    PubMed

    Ma, Hongxing; Chu, Mingjuan; Itagaki, Kiyoshi; Xin, Ping; Zhou, Xuegang; Zhang, Dawei; Wang, Youzhi; Fu, Jia; Sun, Shiqin

    2014-01-01

    The liquid self-emulsifying drug delivery system (L-SEDDS), commonly used to deliver effective but poorly water-soluble oleanolic acid (OA), has many limitations such as high manufacturing costs, few choices of dosage forms, risk of leakage from hard gelatin capsules, low stability, limited portability, incompatibility with capsule materials, and relatively restricted storage conditions. Thus the main purpose of our study was to develop a promising solid lipid-based drug delivery system (S-SEDDS) for OA. The S-SEDDS, prepared from wet granulation with an optimized L-SEDDS formulation and mannitol, was characterized by particle size analysis, scanning electron microscopy, differential scanning calorimetry, and X-ray powder diffraction. Finally, the solubility of the OA-loaded S-SEDDS was compared with that of OA powder in the dissolution assay. Our new S-SEDDS for OA was developed from the optimum L-SEDDS with ethyl oleate (oil phase), Labrasol (surfactant), and Transcutol P (cosurfactant) at a volume ratio of 15:71:14 with 1.5% w/v OA and mannitol. The dissolution of OA was improved by 60% compared with that of the pure OA powder. All the problems associated with the L-SEDDS were resolved. The methodologies we developed for OA delivery could also be utilized for the delivery of other drugs with the S-SEDDS. PMID:25450625

  11. Assembling nanoparticle coatings to improve the drug delivery performance of lipid based colloids

    NASA Astrophysics Data System (ADS)

    Simovic, Spomenka; Barnes, Timothy J.; Tan, Angel; Prestidge, Clive A.

    2012-02-01

    Lipid based colloids (e.g. emulsions and liposomes) are widely used as drug delivery systems, but often suffer from physical instabilities and non-ideal drug encapsulation and delivery performance. We review the application of engineered nanoparticle layers at the interface of lipid colloids to improve their performance as drug delivery systems. In addition we focus on the creation of novel hybrid nanomaterials from nanoparticle-lipid colloid assemblies and their drug delivery applications. Specifically, nanoparticle layers can be engineered to enhance the physical stability of submicron lipid emulsions and liposomes, satbilise encapsulated active ingredients against chemical degradation, control molecular transport and improve the dermal and oral delivery characteristics, i.e. increase absorption, bioavailability and facilitate targeted delivery. It is feasible that hybrid nanomaterials composed of nanoparticles and colloidal lipids are effective encapsulation and delivery systems for both poorly soluble drugs and biological drugs and may form the basis for the next generation of medicines. Additional pre-clinical research including specific animal model studies are required to advance the peptide/protein delivery systems, whereas the silica lipid hybrid systems have now entered human clinical trials for poorly soluble drugs.

  12. Thermo-adjustable mechanical properties of polymer, lipid-based complex fluids

    NASA Astrophysics Data System (ADS)

    Firestone, Millicent; Lee, Sungwon

    2012-02-01

    Combined rheology (oscillatory and steady shear) and SAXS studies reveal details on the temperature-dependent, reversible mechanical properties of nonionic polymer, lipid-based complex fluids. Compositions prepared by introduction of the polymer as either a lipid conjugate or a triblock copolymer form an elastic gel as the temperature is increased to 18 C. The network is produced from PEO chain entanglement and physical crosslinks confined within the intervening aqueous layers of a multilamellar structured lyotropic mesophase. Although the complex fluids are weak gels, tuning of the gel strength can be achieved by temperature adjustment. The sol state formed at reduced temperature arises as a consequence of the well-solvated PEO chains adopting a non-interacting, conformational state. Complex fluids prepared with the triblock copolymers exhibit greater tunability in viscoelasticity than those containing the PEGylated-lipid conjugate because of the temperature-dependent water solubility of the central PPO block. The water solubility of PPO at reduced temperatures results in the polymer being expelled from the self-assembled amphiphilic bilayer, causing collapse of the swollen lamellar structure and loss of the PEO network. At elevated temperatures, the triblock reinserts into the bilayer producing an elastic gel. These studies identify macromolecular architectures for the facile preparation of dynamic soft materials possessing a range of mechanical properties that can be tuned by modest temperature control.

  13. Why Fish Oil Fails: A Comprehensive 21st Century Lipids-Based Physiologic Analysis

    PubMed Central

    Peskin, B. S.

    2014-01-01

    The medical community suffered three significant fish oil failures/setbacks in 2013. Claims that fish oil's EPA/DHA would stop the progression of heart disease were crushed when The Risk and Prevention Study Collaborative Group (Italy) released a conclusive negative finding regarding fish oil for those patients with high risk factors but no previous myocardial infarction. Fish oil failed in all measures of CVD prevention—both primary and secondary. Another major 2013 setback occurred when fish oil's DHA was shown to significantly increase prostate cancer in men, in particular, high-grade prostate cancer, in the Selenium and Vitamin E Cancer Prevention Trial (SELECT) analysis by Brasky et al. Another monumental failure occurred in 2013 whereby fish oil's EPA/DHA failed to improve macular degeneration. In 2010, fish oil's EPA/DHA failed to help Alzheimer's victims, even those with low DHA levels. These are by no means isolated failures. The promise of fish oil and its so-called active ingredients EPA / DHA fails time and time again in clinical trials. This lipids-based physiologic review will explain precisely why there should have never been expectation for success. This review will focus on underpublicized lipid science with a focus on physiology. PMID:24551453

  14. RNA is an Adjuvanticity Mediator for the Lipid-Based Mucosal Adjuvant, Endocine.

    PubMed

    Hayashi, Masayuki; Aoshi, Taiki; Ozasa, Koji; Kusakabe, Takato; Momota, Masatoshi; Haseda, Yasunari; Kobari, Shingo; Kuroda, Etsushi; Kobiyama, Kouji; Coban, Cevayir; Ishii, Ken J

    2016-01-01

    Nasal vaccination has the potential to elicit systemic and mucosal immunity against pathogens. However, split and subunit vaccines lack potency at stimulating mucosal immunity, and an adjuvant is indispensable for eliciting potent mucosal immune response to nasal vaccines. Endocine, a lipid-based mucosal adjuvant, potentiates both systemic and mucosal immune responses. Although Endocine has shown efficacy and tolerability in animal and clinical studies, its mechanism of action remains unknown. It has been reported recently that endogenous danger signals are essential for the effects of some adjuvants such as alum or MF59. However, the contribution of danger signals to the adjuvanticity of Endocine has not been explored. Here, we show that RNA is likely to be an important mediator for the adjuvanticity of Endocine. Administration of Endocine generated nucleic acids release, and activated dendritic cells (DCs) in draining lymph nodes in vivo. These results suggest the possibility that Endocine indirectly activates DCs via damage-associated molecular patterns. Moreover, the adjuvanticity of Endocine disappeared in mice lacking TANK-binding kinase 1 (Tbk1), which is a downstream molecule of nucleic acid sensing signal pathway. Furthermore, co-administration of RNase A reduced the adjuvanticity of Endocine. These data suggest that RNA is important for the adjuvanticity of Endocine. PMID:27374884

  15. In-vitro release of diclofenac diethylammonium from lipid-based formulations.

    PubMed

    Parsaee, Siamak; Sarbolouki, Mohammad N; Parnianpour, Mohamad

    2002-07-01

    This article presents the preparation and topical performance of some new lipid-based formulations of diclofenac, namely (a) a diclofenac aqueous gel containing mixed micelles (sodium cholate:egg lecithin molar ratio 0.55); (b) diclofenac lotion that contains soya lecithin, ethanol and buffer; and (c) diclofenac lipogel containing egg lecithin, isopropyl myristate, propylene glycol and ethanol. Gel formulations were prepared using Carbomer 934. Release of diclofenac from all formulations was monitored via dialysis through Spectra/por membrane into phosphate buffer (0.2 M pH=7.4) using a Franz cell. Drug release profile and diffusion coefficients were compared with brand formulation (Geigy's Vlotaren Emulgel). Statistical analysis of data show that the diffusion coefficient of the drug from these formulations rank according to the following order: Diclofenac lotion (D=5.308x10(-7) cm(2)/s) >lipogel (D=2.102 x 10(-7) cm(2)/s) >Voltaren Emulgel (1.518 x 10(-7) cm(2)/s) >aqueous gel mixed micelle (0.966 x 10(-7) cm(2)/s). These results show that diclofenac lotion and lipogel maybe more suitable formulations than the conventional topical dosage form.

  16. Preparation and characterization of lipid based nanosystems for topical delivery of quercetin.

    PubMed

    Bose, Sonali; Michniak-Kohn, Bozena

    2013-02-14

    The main objective of this study was to evaluate the potential of lipid nanosystems for topical delivery of the naturally occurring flavonoid quercetin. These lipid based nanosystems were manufactured using a solvent free probe ultrasonication process. Formulation factors such as the nature of the lipid (solid/combination of solid and liquid) in solid lipid nanoparticle (SLN) and nanostructured lipid carrier (NLC) systems and drug loading were evaluated to produce an optimum formulation with adequate physical stability for up to 14 weeks at 2-8°C. The mean particle size of the optimized formulation was around 282 nm, with a zeta potential value of -36.57 ± 2.67 mV, indicating the formation of a stable system. Release studies showed a biphasic release profile, characterized by an initial burst release followed by a more controlled release pattern from both SLN and NLC systems. The NLC system showed the highest improvement in topical delivery of quercetin manifested by the amount of quercetin retained in full thickness human skin, compared to a control formulation with similar composition and particle size in the micrometer range. This study demonstrated the feasibility of nanostructured lipid carrier systems for improved topical delivery of quercetin.

  17. Pharmacokinetic aspects and in vitro-in vivo correlation potential for lipid-based formulations.

    PubMed

    Kollipara, Sivacharan; Gandhi, Rajesh Kumar

    2014-10-01

    Lipid-based formulations have been an attractive choice among novel drug delivery systems for enhancing the solubility and bioavailability of poorly soluble drugs due to their ability to keep the drug in solubilized state in the gastrointestinal tract. These formulations offer multiple advantages such as reduction in food effect and inter-individual variability, ease of preparation, and the possibility of manufacturing using common excipients available in the market. Despite these advantages, very few products are available in the present market, perhaps due to limited knowledge in the in vitro tests (for prediction of in vivo fate) and lack of understanding of the mechanisms behind pharmacokinetic and biopharmaceutical aspects of lipid formulations after oral administration. The current review aims to provide a detailed understanding of the in vivo processing steps involved after oral administration of lipid formulations, their pharmacokinetic aspects and in vitro in vivo correlation (IVIVC) perspectives. Various pharmacokinetic and biopharmaceutical aspects such as formulation dispersion and lipid digestion, bioavailability enhancement mechanisms, impact of excipients on efflux transporters, and lymphatic transport are discussed with examples. In addition, various IVIVC approaches towards predicting in vivo data from in vitro dispersion/precipitation, in vitro lipolysis and ex vivo permeation studies are also discussed in detail with help of case studies. PMID:26579403

  18. Assembling nanoparticle coatings to improve the drug delivery performance of lipid based colloids.

    PubMed

    Simovic, Spomenka; Barnes, Timothy J; Tan, Angel; Prestidge, Clive A

    2012-02-21

    Lipid based colloids (e.g. emulsions and liposomes) are widely used as drug delivery systems, but often suffer from physical instabilities and non-ideal drug encapsulation and delivery performance. We review the application of engineered nanoparticle layers at the interface of lipid colloids to improve their performance as drug delivery systems. In addition we focus on the creation of novel hybrid nanomaterials from nanoparticle-lipid colloid assemblies and their drug delivery applications. Specifically, nanoparticle layers can be engineered to enhance the physical stability of submicron lipid emulsions and liposomes, satbilise encapsulated active ingredients against chemical degradation, control molecular transport and improve the dermal and oral delivery characteristics, i.e. increase absorption, bioavailability and facilitate targeted delivery. It is feasible that hybrid nanomaterials composed of nanoparticles and colloidal lipids are effective encapsulation and delivery systems for both poorly soluble drugs and biological drugs and may form the basis for the next generation of medicines. Additional pre-clinical research including specific animal model studies are required to advance the peptide/protein delivery systems, whereas the silica lipid hybrid systems have now entered human clinical trials for poorly soluble drugs.

  19. Pharmacokinetic aspects and in vitro–in vivo correlation potential for lipid-based formulations

    PubMed Central

    Kollipara, Sivacharan; Gandhi, Rajesh Kumar

    2014-01-01

    Lipid-based formulations have been an attractive choice among novel drug delivery systems for enhancing the solubility and bioavailability of poorly soluble drugs due to their ability to keep the drug in solubilized state in the gastrointestinal tract. These formulations offer multiple advantages such as reduction in food effect and inter-individual variability, ease of preparation, and the possibility of manufacturing using common excipients available in the market. Despite these advantages, very few products are available in the present market, perhaps due to limited knowledge in the in vitro tests (for prediction of in vivo fate) and lack of understanding of the mechanisms behind pharmacokinetic and biopharmaceutical aspects of lipid formulations after oral administration. The current review aims to provide a detailed understanding of the in vivo processing steps involved after oral administration of lipid formulations, their pharmacokinetic aspects and in vitro in vivo correlation (IVIVC) perspectives. Various pharmacokinetic and biopharmaceutical aspects such as formulation dispersion and lipid digestion, bioavailability enhancement mechanisms, impact of excipients on efflux transporters, and lymphatic transport are discussed with examples. In addition, various IVIVC approaches towards predicting in vivo data from in vitro dispersion/precipitation, in vitro lipolysis and ex vivo permeation studies are also discussed in detail with help of case studies. PMID:26579403

  20. Metastability in lipid based particles exhibits temporally deterministic and controllable behavior

    PubMed Central

    Jacoby, Guy; Cohen, Keren; Barkan, Kobi; Talmon, Yeshayahu; Peer, Dan; Beck, Roy

    2015-01-01

    The metastable-to-stable phase-transition is commonly observed in many fields of science, as an uncontrolled independent process, highly sensitive to microscopic fluctuations. In particular, self-assembled lipid suspensions exhibit phase-transitions, where the underlying driving mechanisms and dynamics are not well understood. Here we describe a study of the phase-transition dynamics of lipid-based particles, consisting of mixtures of dilauroylphosphatidylethanolamine (DLPE) and dilauroylphosphatidylglycerol (DLPG), exhibiting a metastable liquid crystalline-to-stable crystalline phase transition upon cooling from 60°C to 37°C. Surprisingly, unlike classically described metastable-to-stable phase transitions, the manner in which recrystallization is delayed by tens of hours is robust, predetermined and controllable. Our results show that the delay time can be manipulated by changing lipid stoichiometry, changing solvent salinity, adding an ionophore, or performing consecutive phase-transitions. Moreover, the delay time distribution indicates a deterministic nature. We suggest that the non-stochastic physical mechanism responsible for the delayed recrystallization involves several rate-affecting processes, resulting in a controllable, non-independent metastability. A qualitative model is proposed to describe the structural reorganization during the phase transition. PMID:25820650

  1. Lipids-based nanostructured lipid carriers (NLCs) for improved oral bioavailability of sirolimus.

    PubMed

    Yu, Qin; Hu, Xiongwei; Ma, Yuhua; Xie, Yunchang; Lu, Yi; Qi, Jianping; Xiang, Li; Li, Fengqian; Wu, Wei

    2016-05-01

    The main purpose of this study was to improve the oral bioavailability of sirolimus (SRL), a poorly water-soluble immunosuppressant, by encapsulating into lipids-based nanostructured lipid carriers (NLCs). SRL-loaded NLCs (SRL-NLCs) were prepared by a high-pressure homogenization method with glycerol distearates (PRECIROL ATO-5) as the solid lipid, oleic acid as the liquid lipids, and Tween 80 as the emulsifier. The SRL-NLCs prepared under optimum conditions was spherical in shape with a mean particle size of about 108.3 nm and an entrapment efficiency of 99.81%. In vitro release of SRL-NLCs was very slow, about 2.15% at 12 h, while in vitro lipolysis test showed fast digestion of the NLCs within 1 h. Relative oral bioavailability of SRL-NLCs in Beagle dogs was 1.81-folds that of the commercial nanocrystalline sirolimus tablets Rapamune®. In conclusion, the NLCs show potential to improve the oral bioavailability of SRL. PMID:27187522

  2. RNA is an Adjuvanticity Mediator for the Lipid-Based Mucosal Adjuvant, Endocine

    PubMed Central

    Hayashi, Masayuki; Aoshi, Taiki; Ozasa, Koji; Kusakabe, Takato; Momota, Masatoshi; Haseda, Yasunari; Kobari, Shingo; Kuroda, Etsushi; Kobiyama, Kouji; Coban, Cevayir; Ishii, Ken J.

    2016-01-01

    Nasal vaccination has the potential to elicit systemic and mucosal immunity against pathogens. However, split and subunit vaccines lack potency at stimulating mucosal immunity, and an adjuvant is indispensable for eliciting potent mucosal immune response to nasal vaccines. Endocine, a lipid-based mucosal adjuvant, potentiates both systemic and mucosal immune responses. Although Endocine has shown efficacy and tolerability in animal and clinical studies, its mechanism of action remains unknown. It has been reported recently that endogenous danger signals are essential for the effects of some adjuvants such as alum or MF59. However, the contribution of danger signals to the adjuvanticity of Endocine has not been explored. Here, we show that RNA is likely to be an important mediator for the adjuvanticity of Endocine. Administration of Endocine generated nucleic acids release, and activated dendritic cells (DCs) in draining lymph nodes in vivo. These results suggest the possibility that Endocine indirectly activates DCs via damage-associated molecular patterns. Moreover, the adjuvanticity of Endocine disappeared in mice lacking TANK-binding kinase 1 (Tbk1), which is a downstream molecule of nucleic acid sensing signal pathway. Furthermore, co-administration of RNase A reduced the adjuvanticity of Endocine. These data suggest that RNA is important for the adjuvanticity of Endocine. PMID:27374884

  3. Molecularly imprinted microparticles in lipid-based formulations for sustained release of donepezil.

    PubMed

    Ruela, André Luís Morais; de Figueiredo, Eduardo Costa; de Araújo, Magali Benjamim; Carvalho, Flávia Chiva; Pereira, Gislaine Ribeiro

    2016-10-10

    Donepezil is a drug administered for Alzheimer's disease treatment, and it is a potential template molecule for imprinted microparticles. The precipitation polymerization technique allows the synthesis of spherical imprinted microparticles, and the intermolecular interactions among drug and molecularly imprinted polymers (MIPs) play a promising role for delineating drug delivery systems. Once that donepezil is a poorly-water soluble compound, lipid based-formulations (LBFs) may enhance its oral administration. Based on this, LBFs are useful vehicles to incorporate imprinted microparticles synthesized by precipitation polymerization. In these formulations, the drug dissolved in lipids is accessible to adsorbate in the polymers, and the hydrophobic environment of lipids increases the molecular recognition of MIPs. The formulations based on MIPs using pure oleic acid as vehicle prolong the in vitro release of donepezil up to several hours by a Fickian diffusion mechanism, and it provides a multiphasic release pattern related to the heterogeneity of the binding sites. The modulation of donepezil release from MIPs-based formulations using oil vehicles may contribute to decrease its side effects, possibly regulating its absorption rate in the gastrointestinal tract. These systems represent a novel technological platform to prolong the delivery not only for donepezil, but also for a variety of therapeutics.

  4. Lipid-Based Nanodiscs as Models for Studying Mesoscale Coalescence A Transport Limited Case

    SciTech Connect

    Hu, Andrew; Fan, Tai-Hsi; Katsaras, John; Xia, Yan; Li, Ming; Nieh, Mu-Ping

    2014-01-01

    Lipid-based nanodiscs (bicelles) are able to form in mixtures of long- and short-chain lipids. Initially, they are of uniform size but grow upon dilution. Previously, nanodisc growth kinetics have been studied using time-resolved small angle neutron scattering (SANS), a technique which is not well suited for probing their change in size immediately after dilution. To address this, we have used dynamic light scattering (DLS), a technique which permits the collection of useful data in a short span of time after dilution of the system. The DLS data indicate that the negatively charged lipids in nanodiscs play a significant role in disc stability and growth. Specifically, the charged lipids are most likely drawn out from the nanodiscs into solution, thereby reducing interparticle repulsion and enabling the discs to grow. We describe a population balance model, which takes into account Coulombic interactions and adequately predicts the initial growth of nanodiscs with a single parameter i.e., surface potential. The results presented here strongly support the notion that the disc coalescence rate strongly depends on nanoparticle charge density. The present system containing low-polydispersity lipid nanodiscs serves as a good model for understanding how charged discoidal micelles coalesce.

  5. Preparation and characterization of lipid based nanosystems for topical delivery of quercetin.

    PubMed

    Bose, Sonali; Michniak-Kohn, Bozena

    2013-02-14

    The main objective of this study was to evaluate the potential of lipid nanosystems for topical delivery of the naturally occurring flavonoid quercetin. These lipid based nanosystems were manufactured using a solvent free probe ultrasonication process. Formulation factors such as the nature of the lipid (solid/combination of solid and liquid) in solid lipid nanoparticle (SLN) and nanostructured lipid carrier (NLC) systems and drug loading were evaluated to produce an optimum formulation with adequate physical stability for up to 14 weeks at 2-8°C. The mean particle size of the optimized formulation was around 282 nm, with a zeta potential value of -36.57 ± 2.67 mV, indicating the formation of a stable system. Release studies showed a biphasic release profile, characterized by an initial burst release followed by a more controlled release pattern from both SLN and NLC systems. The NLC system showed the highest improvement in topical delivery of quercetin manifested by the amount of quercetin retained in full thickness human skin, compared to a control formulation with similar composition and particle size in the micrometer range. This study demonstrated the feasibility of nanostructured lipid carrier systems for improved topical delivery of quercetin. PMID:23246734

  6. Mechano-Transduction: From Molecules to Tissues

    PubMed Central

    Pruitt, Beth L.; Dunn, Alexander R.; Weis, William I.; Nelson, W. James

    2014-01-01

    External forces play complex roles in cell organization, fate, and homeostasis. Changes in these forces, or how cells respond to them, can result in abnormal embryonic development and diseases in adults. How cells sense and respond to these mechanical stimuli requires an understanding of the biophysical principles that underlie changes in protein conformation and result in alterations in the organization and function of cells and tissues. Here, we discuss mechano-transduction as it applies to protein conformation, cellular organization, and multi-cell (tissue) function. PMID:25405923

  7. The Molecular Basis of Mechanosensory Transduction

    PubMed Central

    Marshall, Kara L.; Lumpkin, Ellen A.

    2014-01-01

    Multiple senses including hearing, touch, and osmotic regulation, require the ability to convert force into an electrical signal: a process called mechanotransduction. Mechanotransduction occurs through specialized proteins that open an ion channel pore in response to a mechanical stimulus. Many of these proteins remain unidentified in vertebrates, but known mechanotransduction channels in lower organisms provide clues into their identity and mechanism. Bacteria, fruit flies, and nematodes have all been used to elucidate the molecules necessary for force transduction. This chapter discusses many different mechanical senses and takes an evolutionary approach to review the proteins responsible for mechanotransduction in various biological kingdoms. PMID:22399400

  8. Electromechanical Energy Transduction for Hybrid Vehicles

    NASA Astrophysics Data System (ADS)

    Reddy Vanja, Sridhar; Kelly, Michael W.; Caruso, A. N.

    2010-03-01

    Hybrid vehicle technology seeks to reduce the total energy consumption used for vehicle locomotion by recovering and reutilizing kinetic energy that is otherwise unrecovered or dissipated in conventional vehicle deceleration. The goal of the work is to determine the transduction mechanisms that work towards a Carnot efficiency without considering constraints or limitations placed by cost or materials. Specifically, this talk will present ideal thermodynamic models of energy exchange between mechanical, electrostatic, electromechanical and electrochemical devices with a goal of projecting an ideal hybrid vehicle.

  9. Signal transduction mechanisms in plants: an overview

    NASA Technical Reports Server (NTRS)

    Clark, G. B.; Thompson, G. Jr; Roux, S. J.

    2001-01-01

    This article provides an overview on recent advances in some of the basic signalling mechanisms that participate in a wide variety of stimulus-response pathways. The mechanisms include calcium-based signalling, G-protein-mediated-signalling and signalling involving inositol phospholipids, with discussion on the role of protein kinases and phosphatases interspersed. As a further defining feature, the article highlights recent exciting findings on three extracellular components that have not been given coverage in previous reviews of signal transduction in plants, extracellular calmodulin, extracellular ATP, and integrin-like receptors, all of which affect plant growth and development.

  10. Tumor targeting profiling of hyaluronan-coated lipid based-nanoparticles

    NASA Astrophysics Data System (ADS)

    Mizrahy, Shoshy; Goldsmith, Meir; Leviatan-Ben-Arye, Shani; Kisin-Finfer, Einat; Redy, Orit; Srinivasan, Srimeenakshi; Shabat, Doron; Godin, Biana; Peer, Dan

    2014-03-01

    Hyaluronan (HA), a naturally occurring high Mw (HMw) glycosaminoglycan, has been shown to play crucial roles in cell growth, embryonic development, healing processes, inflammation, and tumor development and progression. Low Mw (LMw, <10 kDa) HA has been reported to provoke inflammatory responses, such as induction of cytokines, chemokines, reactive nitrogen species and growth factors. Herein, we prepared and characterized two types of HA coated (LMw and HMw) lipid-based targeted and stabilized nanoparticles (tsNPs) and tested their binding to tumor cells expressing the HA receptor (CD44), systemic immunotoxicity, and biodistribution in tumor bearing mice. In vitro, the Mw of the surface anchored HA had a significant influence on the affinity towards CD44 on B16F10 murine melanoma cells. LMw HA-tsNPs exhibited weak binding, while binding of tsNPs coated with HMw HA was characterized by high binding. Both types of tsNPs had no measured effect on cytokine induction in vivo following intravenous administration to healthy C57BL/6 mice suggesting no immune activation. HMw HA-tsNPs showed enhanced circulation time and tumor targeting specificity, mainly by accumulating in the tumor and its vicinity compared with LMw HA-tsNPs. Finally, we show that methotrexate (MTX), a drug commonly used in cancer chemotherapy, entrapped in HMw HA-tsNPs slowly diffused from the particles with a half-life of 13.75 days, and improved the therapeutic outcome in a murine B16F10 melanoma model compared with NPs suggesting an active cellular targeting beyond the Enhanced Permeability and Retention (EPR) effect. Taken together, these findings have major implications for the use of high molecular weight HA in nanomedicine as a selective and safe active cellular targeting moiety.Hyaluronan (HA), a naturally occurring high Mw (HMw) glycosaminoglycan, has been shown to play crucial roles in cell growth, embryonic development, healing processes, inflammation, and tumor development and progression

  11. Examining the gastrointestinal transit of lipid-based liquid crystalline systems using whole-animal imaging.

    PubMed

    Pham, Anna C; Nguyen, Tri-Hung; Nowell, Cameron J; Graham, Bim; Boyd, Ben J

    2015-12-01

    Lipid-based liquid crystalline (LC) systems have the potential to sustain the oral absorption of poorly water-soluble drugs in vivo, facilitating slow drug release from their complex internal structure. To further evaluate the dynamic relationship between gastric retention and sustained drug absorption for these systems, this study aimed to explore non-invasive X-ray micro-CT imaging as an approach to assess gastric retention. Pharmacokinetic studies were also conducted with cinnarizine-loaded LC formulations to correlate gastric retention of the formulation to drug absorption. The in vivo studies demonstrated the interplay between gastric retention and drug absorption based on the digestibility of the LC structures. An increase in non-digestible phytantriol (PHY) composition in the formulation relative to digestible glyceryl monooleate (GMO) increased the gastric retention, with 68 ± 4 % of formulation intensity remaining at 8 h for 85 % w/w PHY, and 26 ± 9 % for 60 % w/w PHY. Interestingly, it was found that PHY 30 % w/w in GMO provided the highest bioavailability for cinnarizine (CZ) amongst the other combinations, including GMO alone. The studies demonstrated that combining digestible and non-digestible lipids into LC systems allowed for an optimal balance between sustaining drug absorption whilst increasing plasma concentration (C max) over time, leading to enhanced oral bioavailability. The results demonstrate the potential for utilising non-invasive X-ray micro-CT imaging to dynamically assess the GI transit of orally administered liquid crystal-forming formulations.

  12. Tumor Targeting Potential of Lipid-Based Nano-Pharmaceuticals (LNPs)

    NASA Astrophysics Data System (ADS)

    Gupta, Kshitij; Yavlovich, Amichai; Puri, Anu; Blumenthal, Robert

    2013-09-01

    Nanoparticle-mediated targeted drug delivery has become the modality of interest for cancer/tumor therapy as it reduces the undesirable delivery to normal cells and improves efficacy of the pharmaceuticals. Among all the nanosystems, lipid-based nano-pharmaceuticals (LNPs) have been most extensively studied for cancer therapy. Doxil formulation was the first LNP that has been approved for cancer treatment. When conjugated with ligands, LNPs can be targeted to tumor cells. This chapter focuses on the targeting potential of LNPs for cancer therapy. We will discuss the advantages of enhanced permeability and retention (EPR) effect (passive targeting) for preferential tumor accumulation of LNPs, the importance of pegylation to avoid reticulo-endothelial system uptake and active targeting strategies using various targeting ligands that can be coupled to the LNP surface to target the tumor region (tumor cells/tumor vasculature). Targeted LNPs show higher binding affinity, greater intracellular localization and thereby increased cancer cell killing in comparison to non targeted LNPs. However, contrasting reports exist that pose challenges to the notion that targeted LNPs are advantageous. Recent trends have also demonstrated the concept of dual targeting that simultaneously homes LNPs to receptors on the tumor cells and biomarkers expressed on the tumor vasculature. In addition, targeting with multiple ligands on the LNPs has also been explored. These approaches may prove to be a better answer for next generation of LNPs for delivery of anti-cancer agents. However, more extensive studies are required to get their clinical approval in anti-cancer therapy.

  13. Impact of lipid-based nutrient supplementation (LNS) on children's diet adequacy in Western Uganda.

    PubMed

    Ickes, Scott B; Adair, Linda S; Brahe, Catherine A; Thirumurthy, Harsha; Charles, Baguma; Myhre, Jennifer A; Bentley, Margaret E; Ammerman, Alice S

    2015-12-01

    Lipid-based nutrient supplements (LNS) can help treat undernutrition; however, the dietary adequacy of children supplemented with LNS, and household utilisation patterns are not well understood. We assessed diet adequacy and the quality of complementary foods by conducting a diet assessment of 128 Ugandan children, ages 6-59 months, who participated in a 10-week programme for children with moderate acute malnutrition (MAM, defined as weight-for-age z-score < -2). Caregivers were given a weekly ration of 650 kcal day(-1) (126 g day(-1) ) of a peanut/soy LNS. Two 24-h dietary recalls were administered per child. LNS was offered to 86% of targeted children at least once. Among non-breastfed children, over 90% met their estimated average requirement (EAR) cut-points for all examined nutrients. Over 90% of breastfed children met EAR cut-points for nutrient density for most nutrients, except for zinc where 11.7% met cut-points. A lower proportion of both breastfed and non-breastfed children met adjusted EARs for the specific nutritional needs of MAM. Fewer than 20% of breastfed children met EAR nutrient-density guidelines for MAM for zinc, vitamin C, vitamin A and folate. Underweight status, the presence of a father in the child's home, and higher programme attendance were all associated with greater odds of feeding LNS to targeted children. Children in this community-based supplemental feeding programme who received a locally produced LNS exhibited substantial micronutrient deficiencies given the special dietary needs of this population. These results can help inform programme strategies to improve LNS targeting, and highlight potential nutrient inadequacies for consumers of LNS in community-based settings.

  14. Acceptability of three novel lipid-based nutrient supplements among Malawian infants and their caregivers.

    PubMed

    Phuka, John; Ashorn, Ulla; Ashorn, Per; Zeilani, Mamane; Cheung, Yin Bun; Dewey, Kathryn G; Manary, Mark; Maleta, Kenneth

    2011-10-01

    We tested the acceptability of three new lipid-based nutrient supplements (LNSs) in two independent phases among 18 8-12-month-old healthy rural Malawians and their caregivers. In phase 1, acceptability was assessed by offering three new LNSs in random order, and an LNS already determined to be acceptable, Nutributter(®), each added to 30 g of warm maize porridge over three consecutive days. In phase 2, infants from each village were provided one of the new supplements for a 2-week home-use trial. Outcome measures included the amount consumed, time completion of the dose and the maternal rating of likeability on a 5-point scale. The supplements were rated acceptable if consumption was over 50% of the offered dose in phase 1. The mean (95% confidence interval) proportion of the LNS test meals consumed under direct observation was 88% (82-94%) for LNS-10gM, 90% (84-95%) for LNS-20gM, 87% (79-95%) for LNS-20gNoM, and 86% (83-90%) for Nutributter. The median (25th and 75th centile) time (minutes) for completing the offered test meal was 4 (2, 7) for LNS-10gM, 5 (3, 6) for LNS-20gM, 4 (3, 8) for LNS-20gNoM and 4 (2, 6) for Nutributter. During both phases, almost all caregivers rated all study foods very likeable for themselves and their children, with mean scores slightly lower among the caregivers than among the infants. In the home-use phase, the test foods were almost exclusively used by the study participants with minimal sharing with siblings and other household members. Some infants were reported to prefer the new investigational products over traditional complementary food. Considering that the novel LNS was largely acceptable. Efficacy trials are now needed to assess their impact on child growth and development.

  15. Tools for Early Prediction of Drug Loading in Lipid-Based Formulations

    PubMed Central

    2015-01-01

    Identification of the usefulness of lipid-based formulations (LBFs) for delivery of poorly water-soluble drugs is at date mainly experimentally based. In this work we used a diverse drug data set, and more than 2,000 solubility measurements to develop experimental and computational tools to predict the loading capacity of LBFs. Computational models were developed to enable in silico prediction of solubility, and hence drug loading capacity, in the LBFs. Drug solubility in mixed mono-, di-, triglycerides (Maisine 35-1 and Capmul MCM EP) correlated (R2 0.89) as well as the drug solubility in Carbitol and other ethoxylated excipients (PEG400, R2 0.85; Polysorbate 80, R2 0.90; Cremophor EL, R2 0.93). A melting point below 150 °C was observed to result in a reasonable solubility in the glycerides. The loading capacity in LBFs was accurately calculated from solubility data in single excipients (R2 0.91). In silico models, without the demand of experimentally determined solubility, also gave good predictions of the loading capacity in these complex formulations (R2 0.79). The framework established here gives a better understanding of drug solubility in single excipients and of LBF loading capacity. The large data set studied revealed that experimental screening efforts can be rationalized by solubility measurements in key excipients or from solid state information. For the first time it was shown that loading capacity in complex formulations can be accurately predicted using molecular information extracted from calculated descriptors and thermal properties of the crystalline drug. PMID:26568134

  16. Physicochemical characterization of anionic lipid-based ternary siRNA complexes.

    PubMed

    Kapoor, Mamta; Burgess, Diane J

    2012-07-01

    Physicochemical characterization is a useful tool in understanding lipoplex assemblies and their correlation to biological activity. Anionic lipid-based ternary siRNA complexes composed of anionic liposomes (DOPG/DOPE), calcium ions and siRNA, have recently been shown to be safe and efficient in a breast cancer cell culture model. In the present work, the effects of various formulation parameters such as liposome composition (DOPG/DOPE ratio) and anionic lipid/Ca2+/siRNA molar charge ratio, on the physicochemical attributes (particle size, surface charge, siRNA loading efficiency and serum stability) of these ternary anionic lipoplexes were evaluated. Particle size, siRNA loading efficiency and serum stability correlated with the in vitro silencing efficiency of these lipoplexes. For example, large lipoplex particles (5/2.5/1 anionic lipid/Ca2+/siRNA molar charge ratio) showed less efficient silencing while absolute serum stability and high siRNA loading (1.3/2.5/1 anionic lipid/Ca2+/siRNA molar charge ratio), exhibited maximum silencing in breast cancer cells. The physicochemical properties also indicated that the siRNA exists in the complexed and/or encapsulated form within the lipoplexes, depending on the anionic lipid/siRNA charge ratio. Based on these studies a model representing lipid-siRNA association within the anionic lipoplexes prepared under various formulation conditions is proposed. Physicochemical attributes can be utilized to estimate in vitro activity of lipid-siRNA complexes and understand their morphology.

  17. Examining the gastrointestinal transit of lipid-based liquid crystalline systems using whole-animal imaging.

    PubMed

    Pham, Anna C; Nguyen, Tri-Hung; Nowell, Cameron J; Graham, Bim; Boyd, Ben J

    2015-12-01

    Lipid-based liquid crystalline (LC) systems have the potential to sustain the oral absorption of poorly water-soluble drugs in vivo, facilitating slow drug release from their complex internal structure. To further evaluate the dynamic relationship between gastric retention and sustained drug absorption for these systems, this study aimed to explore non-invasive X-ray micro-CT imaging as an approach to assess gastric retention. Pharmacokinetic studies were also conducted with cinnarizine-loaded LC formulations to correlate gastric retention of the formulation to drug absorption. The in vivo studies demonstrated the interplay between gastric retention and drug absorption based on the digestibility of the LC structures. An increase in non-digestible phytantriol (PHY) composition in the formulation relative to digestible glyceryl monooleate (GMO) increased the gastric retention, with 68 ± 4 % of formulation intensity remaining at 8 h for 85 % w/w PHY, and 26 ± 9 % for 60 % w/w PHY. Interestingly, it was found that PHY 30 % w/w in GMO provided the highest bioavailability for cinnarizine (CZ) amongst the other combinations, including GMO alone. The studies demonstrated that combining digestible and non-digestible lipids into LC systems allowed for an optimal balance between sustaining drug absorption whilst increasing plasma concentration (C max) over time, leading to enhanced oral bioavailability. The results demonstrate the potential for utilising non-invasive X-ray micro-CT imaging to dynamically assess the GI transit of orally administered liquid crystal-forming formulations. PMID:26328930

  18. Rational design for multifunctional non-liposomal lipid-based nanocarriers for cancer management: theory to practice

    PubMed Central

    2013-01-01

    Nanomedicines have gained more and more attention in cancer therapy thanks to their ability to enhance the tumour accumulation and the intracellular uptake of drugs while reducing their inactivation and toxicity. In parallel, nanocarriers have been successfully employed as diagnostic tools increasing imaging resolution holding great promises both in preclinical research and in clinical settings. Lipid-based nanocarriers are a class of biocompatible and biodegradable vehicles that provide advanced delivery of therapeutic and imaging agents, improving pharmacokinetic profile and safety. One of most promising engineering challenges is the design of innovative and versatile multifunctional targeted nanotechnologies for cancer treatment and diagnosis. This review aims to highlight rational approaches to design multifunctional non liposomal lipid-based nanocarriers providing an update of literature in this field. PMID:24564841

  19. Activity Dependent Signal Transduction in Skeletal Muscle

    NASA Technical Reports Server (NTRS)

    Hamilton, Susan L.

    1999-01-01

    The overall goals of this project are: 1) to define the initial signal transduction events whereby the removal of gravitational load from antigravity muscles, such as the soleus, triggers muscle atrophy, and 2) to develop countermeasures to prevent this from happening. Our rationale for this approach is that, if countermeasures can be developed to regulate these early events, we could avoid having to deal with the multiple cascades of events that occur downstream from the initial event. One of our major findings is that hind limb suspension causes an early and sustained increase in intracellular Ca(2+) concentration ([Ca (2+)](sub i)). In most cells the consequences of changes in ([Ca (2+)](sub i))depend on the amplitude, frequency and duration of the Ca(2+) signal and on other factors in the intracellular environment. We propose that muscle remodeling in microgravity represents a change in the balance among several CA(2+) regulated signal transduction pathways, in particular those involving the transcription factors NFAT and NFkB and the pro-apoptotic protein BAD. Other Ca(2+) sensitive pathways involving PKC, ras, rac, and CaM kinase II may also contribute to muscle remodeling.

  20. Signal transduction by the growth hormone receptor

    SciTech Connect

    Waters, M.J.; Rowlinson, S.W.; Clarkson, R.W.

    1994-12-31

    It has been proposed that dimerization of identical receptor subunits by growth hormone (GH) is the mechanism of signal transduction across the cell membrane. We present here data with analogs of porcine GH (pGH), with GH receptors (GHR) mutated in the dimerization domain and with monoclonal antibodies to the GHR which indicate that dimerization is necessary but not sufficient for transduction. We also report nuclear uptake of GH both in vivo and in vitro, along with nuclear localization of the receptor and GH-binding protein (GHBP). This suggests that GH acts directly at the nucleus, and one possible target for this action is a rapid increase in transcription of C/EBP delta seen in 3T3-F442A cells in response to GH. This tyrosine kinase-dependent event may be an archetype for induction of other immediate early gene transcription factors which then interact to determine the programming of the subsequent transcriptional response to GH. 29 refs., 1 fig., 1 tab.

  1. Simulated evolution of signal transduction networks.

    PubMed

    Mobashir, Mohammad; Schraven, Burkhart; Beyer, Tilo

    2012-01-01

    Signal transduction is the process of routing information inside cells when receiving stimuli from their environment that modulate the behavior and function. In such biological processes, the receptors, after receiving the corresponding signals, activate a number of biomolecules which eventually transduce the signal to the nucleus. The main objective of our work is to develop a theoretical approach which will help to better understand the behavior of signal transduction networks due to changes in kinetic parameters and network topology. By using an evolutionary algorithm, we designed a mathematical model which performs basic signaling tasks similar to the signaling process of living cells. We use a simple dynamical model of signaling networks of interacting proteins and their complexes. We study the evolution of signaling networks described by mass-action kinetics. The fitness of the networks is determined by the number of signals detected out of a series of signals with varying strength. The mutations include changes in the reaction rate and network topology. We found that stronger interactions and addition of new nodes lead to improved evolved responses. The strength of the signal does not play any role in determining the response type. This model will help to understand the dynamic behavior of the proteins involved in signaling pathways. It will also help to understand the robustness of the kinetics of the output response upon changes in the rate of reactions and the topology of the network.

  2. Driving DNA transposition by lentiviral protein transduction

    PubMed Central

    Cai, Yujia; Mikkelsen, Jacob Giehm

    2014-01-01

    Gene vectors derived from DNA transposable elements have become powerful molecular tools in biomedical research and are slowly moving into the clinic as carriers of therapeutic genes. Conventional uses of DNA transposon-based gene vehicles rely on the intracellular production of the transposase protein from transfected nucleic acids. The transposase mediates mobilization of the DNA transposon, which is typically provided in the context of plasmid DNA. In recent work, we established lentiviral protein transduction from Gag precursors as a new strategy for direct delivery of the transposase protein. Inspired by the natural properties of infecting viruses to carry their own enzymes, we loaded lentivirus-derived particles not only with vector genomes carrying the DNA transposon vector but also with hundreds of transposase subunits. Such particles were found to drive efficient transposition of the piggyBac transposable element in a range of different cell types, including primary cells, and offer a new transposase delivery approach that guarantees short-term activity and limits potential cytotoxicity. DNA transposon vectors, originally developed and launched as a non-viral alternative to viral integrating vectors, have truly become viral. Here, we briefly review our findings and speculate on the perspectives and potential advantages of transposase delivery by lentiviral protein transduction. PMID:25057443

  3. Lipid-based systems as a promising approach for enhancing the bioavailability of poorly water-soluble drugs.

    PubMed

    Cerpnjak, Katja; Zvonar, Alenka; Gašperlin, Mirjana; Vrečer, Franc

    2013-12-01

    Low oral bioavailability as a consequence of low water solubility of drugs is a growing challenge to the development of new pharmaceutical products. One of the most popular approaches of oral bioavailability and solubility enhancement is the utilization of lipid-based drug delivery systems. Their use in product development is growing due to the versatility of pharmaceutical lipid excipients and drug formulations, and their compatibility with liquid, semi-solid, and solid dosage forms. Lipid formulations, such as self-emulsifying (SEDDS), self-microemulsifying SMEDDS) and self- -nanoemulsifying drug delivery systems (SNEDDS) were explored in many studies as an efficient approach for improving the bioavailability and dissolution rate of poorly water-soluble drugs. One of the greatest advantages of incorporating poorly soluble drugs into such formulations is their spontaneous emulsification and formation of an emulsion, microemulsion or nanoemulsion in aqueous media. This review article focuses on the following topics. First, it presents a classification overview of lipid-based drug delivery systems and mechanisms involved in improving the solubility and bioavailability of poorly water-soluble drugs. Second, the article reviews components of lipid-based drug delivery systems for oral use with their characteristics. Third, it brings a detailed description of SEDDS, SMEDDS and SNEDDS, which are very often misused in literature, with special emphasis on the comparison between microemulsions and nanoemulsions. PMID:24451070

  4. Trends in the Assessment of Drug Supersaturation and Precipitation In Vitro Using Lipid-Based Delivery Systems.

    PubMed

    Stillhart, Cordula; Kuentz, Martin

    2016-09-01

    The generation of drug supersaturation close to the absorptive site is an important mechanism of how several formulation technologies enhance oral absorption and bioavailability. Lipid-based formulations belong to the supersaturating drug delivery systems although this is not the only mechanism of how drug absorption is promoted in vivo. Different methods to determine drug supersaturation and precipitation from lipid-based formulations are described in the literature. Experimental in vitro setups vary according to their complexity and proximity to the in vivo conditions and, therefore, some tests are used for early formulation screening, while others better qualify for a later stage of development. The present commentary discusses this rapidly evolving field of in vitro testing with a special focus on the advancements in analytical techniques and new approaches of mechanistic modeling. The importance of considering a drug absorption sink is particularly emphasized. This commentary should help formulators in the pharmaceutical industry as well as in academia to make informed decisions on how to conduct in vitro tests for lipid-based delivery systems and to decide on the implications of experimental results.

  5. Conformation transformation determined by different self-assembled phases in a DNA complex with cationic polyhedral oligomeric silsesquioxane lipid.

    PubMed

    Cui, Li; Chen, Daoyong; Zhu, Lei

    2008-05-01

    In this work, a novel cube-shaped cationic lipid based on the imidazolium salt of polyhedral oligomeric silsesquioxane (POSS) was complexed with double-stranded DNA. Because of the negative spontaneous curvature of the cationic POSS imidazolium lipid, an inverted hexagonal phase resulted above the melting point of POSS crystals. Depending on the competition between the crystallization of POSS molecules and the negative spontaneous curvature of cationic POSS imidazolium lipids, different self-assembled phase morphologies were obtained. A lamellar phase was obtained when the POSS crystallization was relatively slow. When the POSS crystallization was fast, an inverted hexagonal phase was obtained with POSS lamellar crystals grown in the interstitials of DNA cylinders. On the basis of a circular dichroism study, double-stranded DNA adopted the B-form helical conformation in the inverted hexagonal phase, whereas the helical conformation was largely destroyed in the lamellar phase.

  6. Toxicity of cationic lipids and cationic polymers in gene delivery.

    PubMed

    Lv, Hongtao; Zhang, Shubiao; Wang, Bing; Cui, Shaohui; Yan, Jie

    2006-08-10

    Gene therapy, as a promising therapeutics to treat genetic or acquired diseases, has achieved exciting development in the past two decades. Appropriate gene vectors can be crucial for gene transfer. Cationic lipids and polymers, the most important non-viral vectors, have many advantages over viral ones as non-immunogenic, easy to produce and not oncogenic. They hold the promise to replace viral vectors to be used in clinic. However, the toxicity is still an obstacle to the application of non-viral vectors to gene therapy. For overcoming the problem, many new cationic compounds have been developed. This article provides a review with respect to toxicity of cationic lipids and polymers in gene delivery. We evaluate the structural features of cationic compounds and summarize the relationship of toxicity and structure and hope to provide available suggestions on the development of these cationic compounds.

  7. Recombinant Adeno-associated virus (rAAV)-mediated transduction and optogenetic manipulation of cortical neurons in vitro

    NASA Astrophysics Data System (ADS)

    Lange, Wienke; Jin, Lei; Maybeck, Vanessa; Meisenberg, Annika; Baumann, Arnd; Offenhäusser, Andreas

    2014-03-01

    Genetically encoded light-sensitive proteins can be used to manipulate and observe cellular functions. According to different modes of action, these proteins are divided into actuators like the blue-light gated cation channel Channelrhodopsin-2 (ChR2) and detectors like the calcium sensor GCaMP. In order to optogenetically control and study the activity of rat primary cortical neurons, we established a transduction procedure using recombinant Adeno-associated viruses (rAAVs) as gene-ferries. Thereby, we achieved high transduction rates of these neurons with ChR2. In ChR2 expressing neurons, action potentials could be repeatedly and precisely elicited with laser pulses and measured via patch clamp recording.

  8. 50years of oral lipid-based formulations: Provenance, progress and future perspectives.

    PubMed

    Feeney, Orlagh M; Crum, Matthew F; McEvoy, Claire L; Trevaskis, Natalie L; Williams, Hywel D; Pouton, Colin W; Charman, William N; Bergström, Christel A S; Porter, Christopher J H

    2016-06-01

    Lipid based formulations (LBF) provide well proven opportunities to enhance the oral absorption of drugs and drug candidates that sit close to, or beyond, the boundaries of Lipinski's 'rule-of-five' chemical space. Advantages in permeability, efflux and presystemic metabolism are evident; however, the primary benefit is in increases in dissolution and apparent intestinal solubility for lipophilic, poorly water soluble drugs. This review firstly details the inherent advantages of LBF, their general properties and classification, and provides a brief retrospective assessment of the development of LBF over the past fifty years. More detailed analysis of the ability of LBF to promote intestinal solubilisation, supersaturation and absorption is then provided alongside review of the methods employed to assess formulation performance. Critical review of the ability of simple dispersion and more complex in vitro digestion methods to predict formulation performance subsequently reveals marked differences in the correlative ability of in vitro tests, depending on the properties of the drug involved. Notably, for highly permeable low melting drugs e.g. fenofibrate, LBF appear to provide significant benefit in all cases, and sustained ongoing solubilisation may not be required. In other cases, and particularly for higher melting point drugs such as danazol, where re-dissolution of crystalline precipitate drug is likely to be slow, correlations with ongoing solubilisation and supersaturation are more evident. In spite of their potential benefits, one limitation to broader use of LBF is low drug solubility in the excipients employed to generate formulations. Techniques to increase drug lipophilicity and lipid solubility are therefore explored, and in particular those methods that provide for temporary enhancement including lipophilic ionic liquid and prodrug technologies. The transient nature of these lipophilicity increases enhances lipid solubility and LBF viability, but

  9. Localized RNAi therapeutics of chemoresistant grade IV glioma using hyaluronan-grafted lipid-based nanoparticles.

    PubMed

    Cohen, Zvi R; Ramishetti, Srinivas; Peshes-Yaloz, Naama; Goldsmith, Meir; Wohl, Anton; Zibly, Zion; Peer, Dan

    2015-02-24

    Glioblastoma multiforme (GBM) is one of the most infiltrating, aggressive, and poorly treated brain tumors. Progress in genomics and proteomics has paved the way for identifying potential therapeutic targets for treating GBM, yet the vast majority of these leading drug candidates for the treatment of GBM are ineffective, mainly due to restricted passages across the blood-brain barrier. Nanoparticles have been emerged as a promising platform to treat different types of tumors due to their ability to transport drugs to target sites while minimizing adverse effects. Herein, we devised a localized strategy to deliver RNA interference (RNAi) directly to the GBM site using hyaluronan (HA)-grafted lipid-based nanoparticles (LNPs). These LNPs having an ionized lipid were previously shown to be highly effective in delivering small interfering RNAs (siRNAs) into various cell types. LNP's surface was functionalized with hyaluronan (HA), a naturally occurring glycosaminoglycan that specifically binds the CD44 receptor expressed on GBM cells. We found that HA-LNPs can successfully bind to GBM cell lines and primary neurosphers of GBM patients. HA-LNPs loaded with Polo-Like Kinase 1 (PLK1) siRNAs (siPLK1) dramatically reduced the expression of PLK1 mRNA and cumulated in cell death even under shear flow that simulate the flow of the cerebrospinal fluid compared with control groups. Next, a human GBM U87MG orthotopic xenograft model was established by intracranial injection of U87MG cells into nude mice. Convection of Cy3-siRNA entrapped in HA-LNPs was performed, and specific Cy3 uptake was observed in U87MG cells. Moreover, convection of siPLK1 entrapped in HA-LNPs reduced mRNA levels by more than 80% and significantly prolonged survival of treated mice in the orthotopic model. Taken together, our results suggest that RNAi therapeutics could effectively be delivered in a localized manner with HA-coated LNPs and ultimately may become a therapeutic modality for GBM.

  10. Effects of lipophilic components on the compatibility of lipid-based formulations with hard gelatin capsules.

    PubMed

    Chen, Feng-Jing; Etzler, Frank M; Ubben, Johanna; Birch, Amy; Zhong, Li; Schwabe, Robert; Dudhedia, Mayur S

    2010-01-01

    The present study investigated the effect of lipophilic components on the compatibility of propylene glycol (PG)-containing lipid-based drug delivery system (LBDDS) formulations with hard gelatin capsules. The presence of a lipophilic active pharmaceutical ingredient (API) (log P approximately 6.1) and an additional lipophilic excipient (Capmul MCM) significantly affected the activity of PG in the fills and the equilibrium of PG between capsule shells and fills. These changes in activity and equilibrium of PG were furthermore correlated to the mechanical and thermal properties of the liquid-filled capsules and subsequently linked to the shelf-life of the capsules on stability with respect to capsule deformation. The present study also investigated the mechanism by which lipophilic component(s) might affect the activity of PG in the fill formulations and the equilibrium of PG between capsule shells and fills. The activities of PG in two series of "binary" mixtures with Capmul MCM and with Cremophor EL were measured, respectively. The mixtures of PG containing Capmul MCM were found to be more nearly ideal than those containing Cremophor EL. The observed negative deviation from Rauolt's law indicates that the excess free energies of mixing are less then zero indicating favorable interaction between PG and the other component. It is speculated that enhanced hydrogen bonding opportunities with Cremophor EL are responsible for the decreased excess free energy of mixing. Replacement of Cremophor EL with lipophilic API also reduces the hydrogen bonding opportunities for PG in the mixtures. This hypothesis may further explain the increased activity of PG in the fills and the shifted equilibrium of PG toward the capsule shells. Activity determination utilizing headspace gas chromatography (GC) using short 30 min incubation time seems to be a time-efficient approach for assessing capsule-fill compatibility. Direct measurements of PG migration and other physical properties of

  11. Interactions of lipid-based liquid crystalline nanoparticles with model and cell membranes.

    PubMed

    Barauskas, Justas; Cervin, Camilla; Jankunec, Marija; Spandyreva, Marija; Ribokaite, Kristina; Tiberg, Fredrik; Johnsson, Markus

    2010-05-31

    Lipid-based liquid crystalline nanoparticles (LCNPs) are interesting candidates for drug delivery applications, for instance as solubilizing or encapsulating carriers for intravenous (i.v.) drugs. Here it is important that the carriers are safe and tolerable and do not have, e.g. hemolytic activity. In the present study we have studied LCNP particles of different compositions with respect to their mixing behavior and membrane destabilizing effects in model and cell membrane systems. Different types of non-lamellar LCNPs were studied including cubic phase nanoparticles (Cubosome) based on glycerol monooleate (GMO), hexagonal phase nanoparticles (Hexosome) based on diglycerol monooleate (DGMO) and glycerol dioleate (GDO), sponge phase nanoparticles based on DGMO/GDO/polysorbate 80 (P80) and non-lamellar nanoparticles based on soy phosphatidylcholine (SPC)/GDO. Importantly, the LCNPs based on the long-chain monoacyl lipid, GMO, were shown to display a very fast and complete lipid mixing with model membranes composed of multilamellar SPC liposomes as assessed by a fluorescence energy transfer (FRET) assay. The result correlated well with pronounced hemolytic properties observed when the GMO-based LCNPs were mixed with rat whole blood. In sharp contrast, LCNPs based on mixtures of the long-chain diacyl lipids, SPC and GDO, were found to be practically inert towards both hemolysis in rat whole blood as well as lipid mixing with SPC model membranes. The LCNP dispersions based on a mixture of long-chain monoacyl and diacyl lipids, DGMO/GDO, displayed an intermediate behavior compared to the GMO and SPC/GDO-based systems with respect to both hemolysis and lipid mixing. It is concluded that GMO-based LCNPs are unsuitable for parenteral drug delivery applications (e.g. i.v. administration) while the SPC/GDO-based LCNPs exhibit good properties with limited lipid mixing and hemolytic activity. The correlation between results from lipid mixing or FRET experiments and the in

  12. Hedgehog Secretion and Signal Transduction in Vertebrates

    PubMed Central

    Ryan, Kaitlyn E.; Chiang, Chin

    2012-01-01

    Signaling by the Hedgehog (Hh) family of secreted proteins is essential for proper embryonic patterning and development. Dysregulation of Hh signaling is associated with a variety of human diseases ranging from developmental disorders such as holoprosencephaly to certain forms of cancer, including medulloblastoma and basal cell carcinoma. Genetic studies in flies and mice have shaped our understanding of Hh signaling and revealed that nearly all core components of the pathway are highly conserved. Although many aspects of the Drosophila Hh pathway are conserved in vertebrates, mechanistic differences between the two species have begun to emerge. Perhaps the most striking divergence in vertebrate Hh signaling is its dependence on the primary cilium, a vestigial organelle that is largely absent in flies. This minireview will provide an overview of Hh signaling and present recent insights into vertebrate Hh secretion, receptor binding, and signal transduction. PMID:22474285

  13. Transduction of mechanical strain in bone

    NASA Technical Reports Server (NTRS)

    Duncan, R. L.

    1995-01-01

    One physiologic consequence of extended periods of weightlessness is the rapid loss of bone mass associated with skeletal unloading. Conversely, mechanical loading has been shown to increase bone formation and stimulate osteoblastic function. The mechanisms underlying mechanotransduction, or how the osteoblast senses and converts biophysical stimuli into cellular responses has yet to be determined. For non-innervated mechanosensitive cells like the osteoblast, mechanotransduction can be divided into four distinct phases: 1) mechanocoupling, or the characteristics of the mechanical force applied to the osteoblast, 2) biochemical coupling, or the mechanism through which mechanical strain is transduced into a cellular biochemical signal, 3) transmission of signal from sensor to effector cell and 4) the effector cell response. This review examines the characteristics of the mechanical strain encountered by osteoblasts, possible biochemical coupling mechanisms, and how the osteoblast responds to mechanical strain. Differences in osteoblastic responses to mechanical strain are discussed in relation to the types of strain encountered and the possible transduction pathways involved.

  14. Nonequilibrium phase transitions in biomolecular signal transduction

    NASA Astrophysics Data System (ADS)

    Smith, Eric; Krishnamurthy, Supriya; Fontana, Walter; Krakauer, David

    2011-11-01

    We study a mechanism for reliable switching in biomolecular signal-transduction cascades. Steady bistable states are created by system-size cooperative effects in populations of proteins, in spite of the fact that the phosphorylation-state transitions of any molecule, by means of which the switch is implemented, are highly stochastic. The emergence of switching is a nonequilibrium phase transition in an energetically driven, dissipative system described by a master equation. We use operator and functional integral methods from reaction-diffusion theory to solve for the phase structure, noise spectrum, and escape trajectories and first-passage times of a class of minimal models of switches, showing how all critical properties for switch behavior can be computed within a unified framework.

  15. Green Light to Illuminate Signal Transduction Events

    PubMed Central

    Balla, Tamas

    2009-01-01

    When cells are exposed to hormones that act on cell surface receptors, information is processed through the plasma membrane into the cell interior via second messengers generated in the inner leaflet of the plasma membrane. Individual biochemical steps along this cascade, starting with ligand binding to receptors to activation of guanine nucleotide binding proteins and their downstream effectors such as adenylate cyclase or phospholipase C, have been biochemically characterized. However, the complexity of temporal and spatial integration of these molecular events requires that they be studied in intact cells. The great expansion of fluorescent techniques and improved imaging technologies such as confocal- and TIRF microscopy combined with genetically engineered protein modules has provided a completely new approach to signal transduction research. Spatial definition of biochemical events followed with real-time temporal resolution has become a standard goal and we are breaking the resolution barrier of light microscopes with several new techniques. PMID:19818623

  16. Calcium and signal transduction in plants

    NASA Technical Reports Server (NTRS)

    Poovaiah, B. W.; Reddy, A. S.

    1993-01-01

    Environmental and hormonal signals control diverse physiological processes in plants. The mechanisms by which plant cells perceive and transduce these signals are poorly understood. Understanding biochemical and molecular events involved in signal transduction pathways has become one of the most active areas of plant research. Research during the last 15 years has established that Ca2+ acts as a messenger in transducing external signals. The evidence in support of Ca2+ as a messenger is unequivocal and fulfills all the requirements of a messenger. The role of Ca2+ becomes even more important because it is the only messenger known so far in plants. Since our last review on the Ca2+ messenger system in 1987, there has been tremendous progress in elucidating various aspects of Ca(2+) -signaling pathways in plants. These include demonstration of signal-induced changes in cytosolic Ca2+, calmodulin and calmodulin-like proteins, identification of different Ca2+ channels, characterization of Ca(2+) -dependent protein kinases (CDPKs) both at the biochemical and molecular levels, evidence for the presence of calmodulin-dependent protein kinases, and increased evidence in support of the role of inositol phospholipids in the Ca(2+) -signaling system. Despite the progress in Ca2+ research in plants, it is still in its infancy and much more needs to be done to understand the precise mechanisms by which Ca2+ regulates a wide variety of physiological processes. The purpose of this review is to summarize some of these recent developments in Ca2+ research as it relates to signal transduction in plants.

  17. Phototaxis and sensory transduction in Euglena.

    PubMed

    Diehn, B

    1973-09-14

    The accumulation of Euglena gracilis in an illuminated region is brought about by two main mechanisms: orientation and subsequent directed movement (positive phototaxis) toward light scattered from particles in the illuminated zone; and by the trapping of cells in this region because of shock reactions experienced upon the cells encountering a sudden decrease of light intensity at the light-dark boundary (inverse photophobic responses). Phototactic orientation is mediated by inverse photophobic reactions which occur when the shadow of the stigma periodically falls upon the photoreceptor proper. Euglena also exhibits shock reactions when an already high light intensity is increased further (direct photophobic responses). The expression of both types of phobic responses depends upon stimulus intensity and adaptation of the sensory system in a seemingly complex way. A definition of the minimum components of the stimulus transduction system and a systems analytical approach to the study of input-output relationships enables one to construct an electronic analog of the cell's signal processing system that converts the photoreceptor input to commands which activate or inhibit flagellar reorientation. Computer simulation studies show that this model has considerable predictive value. It is hoped that with the approach presented in this article, a generalized model has become available for dealing with the questions of sensory transduction in aneural systems. Certainly, at this point more questions have been raised than have been answered. Where is the processing device located? Are its kinetic properties determined by electrical processes or by the rates of chemical reactions? Is the processor, and thereby the behavior of the orgamism, modulated by natural environmental parameters, and can it be modified permanently through more drastic chemical treatment of the cell? Is the system capable of permanent or transitory modification through repeated response, that is, does it

  18. Studying Cellular Signal Transduction with OMIC Technologies

    PubMed Central

    Landry, Benjamin D.; Clarke, David C.; Lee, Michael J.

    2016-01-01

    In the gulf between genotype and phenotype exists proteins and, in particular, protein signal transduction systems. These systems use a relatively limited parts list to respond to a much longer list of extracellular, environmental, and/or mechanical cues with rapidity and specificity. Most signaling networks function in a highly nonlinear and often contextual manner. Furthermore, these processes occur dynamically across space and time. Because of these complexities, systems and “OMIC” approaches are essential for the study of signal transduction. One challenge in using OMIC-scale approaches to study signaling is that the “signal” can take different forms in different situations. Signals are encoded in diverse ways such as protein-protein interactions, enzyme activities, localizations, or post-translational modifications to proteins. Furthermore, in some cases signals may be encoded only in the dynamics, duration, or rates of change of these features. Accordingly, systems-level analyses of signaling may need to integrate multiple experimental and/or computational approaches. As the field has progressed, the non-triviality of integrating experimental and computational analyses has become apparent. Successful use of OMIC methods to study signaling will require the “right” experiments and the “right” modeling approaches, and it is critical to consider both in the design phase of the project. In this review, we discuss common OMIC and modeling approaches for studying signaling, emphasizing the philosophical and practical considerations for effectively merging these two types of approaches to maximize the probability of obtaining reliable and novel insights into signaling biology. PMID:26244521

  19. Striatal signal transduction and drug addiction.

    PubMed

    Philibin, Scott D; Hernandez, Adan; Self, David W; Bibb, James A

    2011-01-01

    Drug addiction is a severe neuropsychiatric disorder characterized by loss of control over motivated behavior. The need for effective treatments mandates a greater understanding of the causes and identification of new therapeutic targets for drug development. Drugs of abuse subjugate normal reward-related behavior to uncontrollable drug-seeking and -taking. Contributions of brain reward circuitry are being mapped with increasing precision. The role of synaptic plasticity in addiction and underlying molecular mechanisms contributing to the formation of the addicted state are being delineated. Thus we may now consider the role of striatal signal transduction in addiction from a more integrative neurobiological perspective. Drugs of abuse alter dopaminergic and glutamatergic neurotransmission in medium spiny neurons of the striatum. Dopamine receptors important for reward serve as principle targets of drugs abuse, which interact with glutamate receptor signaling critical for reward learning. Complex networks of intracellular signal transduction mechanisms underlying these receptors are strongly stimulated by addictive drugs. Through these mechanisms, repeated drug exposure alters functional and structural neuroplasticity, resulting in transition to the addicted biological state and behavioral outcomes that typify addiction. Ca(2+) and cAMP represent key second messengers that initiate signaling cascades, which regulate synaptic strength and neuronal excitability. Protein phosphorylation and dephosphorylation are fundamental mechanisms underlying synaptic plasticity that are dysregulated by drugs of abuse. Increased understanding of the regulatory mechanisms by which protein kinases and phosphatases exert their effects during normal reward learning and the addiction process may lead to novel targets and pharmacotherapeutics with increased efficacy in promoting abstinence and decreased side effects, such as interference with natural reward, for drug addiction.

  20. High frequency generalized transduction by miniMu plasmid phage.

    PubMed

    Wang, B M; Liu, L; Groisman, E A; Casadaban, M J; Berg, C M

    1987-06-01

    Deletion derivatives of phage Mu which replicate as multicopy plasmids, and also transpose and package like Mu, have been developed for the in vivo cloning of bacterial genes. We show here that these miniMu plasmid phage are also efficient at generalized transduction and that both in vivo cloning and generalized transduction of a given gene can be accomplished in a single experiment.

  1. Separate TRP channels mediate amplification and transduction in drosophila

    NASA Astrophysics Data System (ADS)

    Lehnert, Brendan P.; Baker, Allison E.; Wilson, Rachel I.

    2015-12-01

    Auditory receptor cells rely on mechanically-gated channels to transform sound stimuli into neural activity. Several TRP channels have been implicated in Drosophila auditory transduction, but mechanistic studies have been hampered by the inability to record subthreshold signals from receptor neurons. We developed a non-invasive method for measuring these signals by recording from a central neuron that is electrically coupled to a genetically-defined population of auditory receptors. We find that the TRPN family member NompC, which is necessary for the active amplification of motion by the auditory organ, is not required for transduction. Instead, NompC sensitizes the transduction complex to movement and precisely regulates the static forces on the complex. In contrast, the TRPV channels Nanchung and Inactive are required for responses to sound, suggesting they are components of the transduction complex. Thus, transduction and active amplification are genetically separable processes in Drosophila hearing.

  2. An intimate link: two-component signal transduction systems and metal transport systems in bacteria

    PubMed Central

    Singh, Kamna; Senadheera, Dilani B; Cvitkovitch, Dennis G

    2014-01-01

    Bacteria have evolved various strategies to contend with high concentrations of environmental heavy metal ions for rapid, adaptive responses to maintain cell viability. Evidence gathered in the past two decades suggests that bacterial two-component signal transduction systems (TCSTSs) are intimately involved in monitoring cation accumulation, and can regulate the expression of related metabolic and virulence genes to elicit adaptive responses to changes in the concentration of these ions. Using examples garnered from recent studies, we summarize the cross-regulatory relationships between metal ions and TCSTSs. We present evidence of how bacterial TCSTSs modulate metal ion homeostasis and also how metal ions, in turn, function to control the activities of these signaling systems linked with bacterial survival and virulence. PMID:25437189

  3. The Membrane and Lipids as Integral Participants in Signal Transduction: Lipid Signal Transduction for the Non-Lipid Biochemist

    ERIC Educational Resources Information Center

    Eyster, Kathleen M.

    2007-01-01

    Reviews of signal transduction have often focused on the cascades of protein kinases and protein phosphatases and their cytoplasmic substrates that become activated in response to extracellular signals. Lipids, lipid kinases, and lipid phosphatases have not received the same amount of attention as proteins in studies of signal transduction.…

  4. The Cation-π Interaction

    PubMed Central

    DOUGHERTY, DENNIS A.

    2014-01-01

    CONSPECTUS The chemistry community now recognizes the cation-π interaction as a major force for molecular recognition, joining the hydrophobic effect, the hydrogen bond, and the ion pair in determining macromolecular structure and drug-receptor interactions. This Account provides the author’s perspective on the intellectual origins and fundamental nature of the cation-π interaction. Early studies on cyclophanes established that water-soluble, cationic molecules would forgo aqueous solvation to enter a hydrophobic cavity if that cavity was lined with π systems. Important gas phase studies established the fundamental nature of the cation-π interaction. The strength of the cation-π interaction – Li+ binds to benzene with 38 kcal/mol of binding energy; NH4+ with 19 kcal/mol– distinguishes it from the weaker polar-π interactions observed in the benzene dimer or water-benzene complexes. In addition to the substantial intrinsic strength of the cation-π interaction in gas phase studies, the cation-π interaction remains energetically significant in aqueous media and under biological conditions. Many studies have shown that cation-π interactions can enhance binding energies by 2 – 5 kcal/mol, making them competitive with hydrogen bonds and ion pairs in drug-receptor and protein-protein interactions. As with other noncovalent interactions involving aromatic systems, the cation-π interaction includes a substantial electrostatic component. The six (four) Cδ−–Hδ+ bond dipoles of a molecule like benzene (ethylene) combine to produce a region of negative electrostatic potential on the face of the π system. Simple electrostatics facilitate a natural attraction of cations to the surface. The trend for (gas phase) binding energies is Li+>Na+>K+>Rb+: as the ion gets larger the charge is dispersed over a larger sphere and binding interactions weaken, a classical electrostatic effect. On other hand, polarizability does not define these interactions. Cyclohexane

  5. Structural Insights into Divalent Cation Modulations of ATP-Gated P2X Receptor Channels.

    PubMed

    Kasuya, Go; Fujiwara, Yuichiro; Takemoto, Mizuki; Dohmae, Naoshi; Nakada-Nakura, Yoshiko; Ishitani, Ryuichiro; Hattori, Motoyuki; Nureki, Osamu

    2016-02-01

    P2X receptors are trimeric ATP-gated cation channels involved in physiological processes ranging widely from neurotransmission to pain and taste signal transduction. The modulation of the channel gating, including that by divalent cations, contributes to these diverse physiological functions of P2X receptors. Here, we report the crystal structure of an invertebrate P2X receptor from the Gulf Coast tick Amblyomma maculatum in the presence of ATP and Zn(2+) ion, together with electrophysiological and computational analyses. The structure revealed two distinct metal binding sites, M1 and M2, in the extracellular region. The M1 site, located at the trimer interface, is responsible for Zn(2+) potentiation by facilitating the structural change of the extracellular domain for pore opening. In contrast, the M2 site, coupled with the ATP binding site, might contribute to regulation by Mg(2+). Overall, our work provides structural insights into the divalent cation modulations of P2X receptors. PMID:26804916

  6. Depletion of bitter taste transduction leads to massive spermatid loss in transgenic mice.

    PubMed

    Li, Feng; Zhou, Minliang

    2012-06-01

    Bitter taste perception is an important sensory input warning against the ingestion of toxic and noxious substances. Bitter receptors, a family of ~30 highly divergent G-protein-coupled receptors, are exclusively expressed in taste receptor cells that contain the G-protein α-subunit gustducin, bind to α-gustducin in vitro, and respond to bitter tastes in functional expression assays. We generated a taste receptor type 2 member 5 (T2R5)-Cre/green fluorescent protein reporter transgenic mouse to investigate the tissue distribution of T2R5. Our results showed that Cre gene expression in these mice was faithful to the expression of T2R5 in taste tissue. More surprisingly, immunostaining and X-gal staining revealed T2R5 expression in the testis. Ablation of T2R5 + cells led to a smaller testis and removed the spermatid phase from most of the seminiferous tubules. The entire taste transduction cascade (α-gustducin, Ggamma13, phospholipase Cβ2) was detected in spermatogenesis, whereas transient receptor potential, cation channel subfamily M member 5 (Trpm5), was observed only in the later spermatid phase. In short, our results indicate that the taste transduction cascade may be involved in spermatogenesis. PMID:22266327

  7. Diarylferrocene tweezers for cation binding.

    PubMed

    Lima, Carlos F R A C; Fernandes, Ana M; Melo, André; Gonçalves, Luís M; Silva, Artur M S; Santos, Luís M N B F

    2015-10-01

    The host-guest chemistry of ferrocene derivatives was explored by a combined experimental and theoretical study. Several 1-arylferrocenes and 1,1'-diarylferrocenes were synthesized by the Suzuki-Miyaura cross-coupling reaction. The ability of these compounds to bind small cations in the gas phase was investigated experimentally by electrospray ionization mass spectrometry (ESI-MS). The results evidenced a noticeable ability of all 1,1'-diarylferrocenes studied to bind cations, while the same was not observed for the corresponding 1-arylferrocenes nor ferrocene. The 1,1'-diarylferrocenecation relative interaction energies were evaluated by ESI-MS and quantum chemical calculations and showed that cation binding in these systems follows electrostatic trends. It was found that, due to their unique molecular shape and smooth torsional potentials, 1,1'-diarylferrocenes can act as molecular tweezers of small-sized cations in the gas phase. PMID:26309143

  8. The effect of neutral helper lipids on the structure of cationic lipid monolayers

    PubMed Central

    Dabkowska, A. P.; Barlow, D. J.; Hughes, A. V.; Campbell, R. A.; Quinn, P. J.; Lawrence, M. J.

    2012-01-01

    Successful drug delivery via lipid-based systems has often been aided by the incorporation of ‘helper lipids’. While these neutral lipids enhance the effectiveness of cationic lipid-based delivery formulations, many questions remain about the nature of their beneficial effects. The structure of monolayers of the cationic lipid dimethyldioctadecylammonium bromide (DODAB) alone, and mixed with a neutral helper lipid, either diolelyphosphatidylethanolamine or cholesterol at a 1 : 1 molar ratio was investigated at the air–water interface using a combination of surface pressure–area isotherms, Brewster angle microscopy (BAM) and specular neutron reflectivity in combination with contrast variation. BAM studies showed that while pure DODAB and DODAB with cholesterol monolayers showed fairly homogeneous surfaces, except in the regions of phase transition, monolayers of DODAB with diolelyphosphatidylethanolamine were, in contrast, inhomogeneous exhibiting irregular bean-shaped domains throughout. Neutron reflectivity data showed that while the thickness of the DODAB monolayer increased from 17 to 24 Å as it was compressed from a surface pressure of 5–40 mN m−1, the thickness of the helper lipid-containing monolayers, over the same range of surface pressures, was relatively invariant at between 25 and 27 Å. In addition, the monolayers containing diolelyphosphatidylethanolamine were found to be more heavily hydrated than the monolayers of cationic lipid, alone or in combination with cholesterol, with hydration levels of 18 molecules of water per molecule of lipid being recorded for the diolelyphosphatidylethanolamine-containing monolayers at a surface pressure of 30 mN m−1 compared with only six and eight molecules of water per molecule of lipid for the pure DODAB monolayer and the cholesterol-containing DODAB monolayer, respectively. PMID:21831895

  9. Effect of propranolol on platelet signal transduction.

    PubMed Central

    Dash, D; Rao, K

    1995-01-01

    Propranolol inhibits platelet secondary aggregation and secretion by mechanisms unrelated to its beta-adrenergic-blocking activity. We previously reported that a major effect of the drug is perturbation of the physical microenvironment of the human platelet membrane. To explore further the molecular mechanisms underlying propranolol-mediated platelet inhibition, we studied protein kinase C activity, estimated from the phosphorylation of the substrate protein pleckstrin, in propranolol-treated human platelets. The drug inhibited activation of the enzyme in thrombin-stimulated platelets but not in platelets stimulated with phorbol esters, indicating that its site of action might be upstream of protein kinase C. It also inhibited the activity of phospholipase C, determined from the extent of generation of inositol phosphates and phosphatidic acid, in platelets stimulated with thrombin as well as the non-hydrolysable GTP analogue guanosine 5'-[beta, gamma-imido]triphosphate in a dose-dependent manner. These data suggest that propranolol inhibits signal transduction in thrombin-stimulated platelets by interacting at the level of phospholipase C and exclude interaction of the drug with the downstream effector enzyme protein kinase C. Images Figure 1 Figure 2 Figure 3 PMID:7619088

  10. Glycosphingolipid–Protein Interaction in Signal Transduction

    PubMed Central

    Russo, Domenico; Parashuraman, Seetharaman; D’Angelo, Giovanni

    2016-01-01

    Glycosphingolipids (GSLs) are a class of ceramide-based glycolipids essential for embryo development in mammals. The synthesis of specific GSLs depends on the expression of distinctive sets of GSL synthesizing enzymes that is tightly regulated during development. Several reports have described how cell surface receptors can be kept in a resting state or activate alternative signalling events as a consequence of their interaction with GSLs. Specific GSLs, indeed, interface with specific protein domains that are found in signalling molecules and which act as GSL sensors to modify signalling responses. The regulation exerted by GSLs on signal transduction is orthogonal to the ligand–receptor axis, as it usually does not directly interfere with the ligand binding to receptors. Due to their properties of adjustable production and orthogonal action on receptors, GSLs add a new dimension to the control of the signalling in development. GSLs can, indeed, dynamically influence progenitor cell response to morphogenetic stimuli, resulting in alternative differentiation fates. Here, we review the available literature on GSL–protein interactions and their effects on cell signalling and development. PMID:27754465

  11. Signal transduction activated by cannabinoid receptors.

    PubMed

    Díaz-Laviada, Inés; Ruiz-Llorente, Lidia

    2005-07-01

    Since the discovery that cannabinoids exert biological actions through binding to specific receptors, signal mechanisms triggered by these receptors have been focus of extensive study. This review summarizes the current knowledge of the signalling events produced by cannabinoids from membrane receptors to downstream regulators. Two types of cannabinoid receptors have been identified to date: CB(1) and CB(2) both belonging to the heptahelichoidal receptor family but with different tissue distribution and signalling mechanisms. Coupling to inhibitory guanine nucleotide-binding protein and thus inhibition of adenylyl cyclase has been observed in both receptors but other signal transduction pathways that are regulated or not by these G proteins are differently activated upon ligand-receptor binding including ion channels, sphingomyelin hydrolysis, ceramide generation, phospholipases activation and downstream targets as MAP kinase cascade, PI3K, FAK or NOS regulation. Cannabinoids may also act independently of CB(1)or CB(2) receptors. The existence of new unidentified putative cannabinoid receptors has been claimed by many investigators. Endocannabinoids activate vanilloid TRPV1 receptors that may mediate some of the cannabinoid effects. Other actions of cannabinoids can occur through non-receptor-mediated mechanisms.

  12. Confocal Scanner for Highly Sensitive Photonic Transduction of Nanomechanical Resonators

    NASA Astrophysics Data System (ADS)

    Diao, Zhu; Losby, Joseph E.; Sauer, Vincent T. K.; Westwood, Jocelyn N.; Freeman, Mark R.; Hiebert, Wayne K.

    2013-06-01

    We show that a simple confocal laser scanning system can be used to couple light through grating couplers into nanophotonic circuits. The coupling efficiency is better than 15% per coupler. Our technique avoids using multi-axis fibre stages and is especially advantageous when the nanophotonic circuit is kept in vacuum, e.g., for nanomechanical resonator displacement transduction. This was demonstrated by recording the resonant response of a nanomechanical doubly clamped beam embedded in a race-track optical cavity. The nanophotonic transduction offers an increase of two orders of magnitude in transduction responsivity compared with conventional free-space optical interferometry.

  13. Ultrasonic Transduction of DNA into Central Nervous System Cells

    NASA Astrophysics Data System (ADS)

    Manome, Yoshinobu; Nakayama, Naoto; Furuhata, Hiroshi

    2005-03-01

    Many diseases involving the central nervous system are intractable to conventional therapies, thereby requiring an alternative treatment such as gene therapy. Therapy requires safety since the central nervous system is a critical organ. The choice of non-viral vectors, such as naked plasmid DNA, may have merit. However, transduction efficiencies of these vectors are low. We have investigated the use of ultrasound and found that insonation effectively enhanced transduction of naked plasmid DNA into cultured slices of mouse brain. Since ultrasound successfully facilitated the transduction of naked plasmid DNA into the neural tissue, this approach may have a role in gene therapy for the central nervous system.

  14. The Precipitation Behavior of Poorly Water-Soluble Drugs with an Emphasis on the Digestion of Lipid Based Formulations.

    PubMed

    Khan, Jamal; Rades, Thomas; Boyd, Ben

    2016-03-01

    An increasing number of newly discovered drugs are poorly water-soluble and the use of natural and synthetic lipids to improve the oral bioavailability of these drugs by utilizing the digestion pathway in-vivo has proved an effective formulation strategy. The mechanisms responsible for lipid digestion and drug solubilisation during gastrointestinal transit have been explored in detail, but the implications of drug precipitation beyond the potential adverse effect on bioavailability have received attention only in recent years. Specifically, these implications are that different solid forms of drug on precipitation may affect the total amount of drug absorbed in-vivo through their different physico-chemical properties, and the possibility that the dynamic environment of the small intestine may afford re-dissolution of precipitated drug if present in a high-energy form. This review describes the events that lead to drug precipitation during the dispersion and digestion of lipid based formulations, common methods used to inhibit precipitation, as well as conventional and newly emerging characterization techniques for studying the solid state form of the precipitated drug. Moreover, selected case studies are discussed where drug precipitation has ensued from the digestion of lipid based formulations, as well as the apparent link between drug ionisability and altered solid forms on precipitation, culminating in a discussion about the importance of the solid form on precipitation with relevance to the total drug absorbed.

  15. Lipid-based nanocarriers for drug delivery and targeting: a patent survey of methods of production and characterization.

    PubMed

    Carbone, Claudia; Cupri, Sarha; Leonardi, Antonio; Puglisi, Giovanni; Pignatello, Rosario

    2013-09-01

    Among the colloidal vectors proposed for the controlled delivery and targeting of drugs and other biologically active compounds, lipid-based nanocarriers are acquiring an increasing role due to a number of peculiar technological and physical features. Solid lipid nanoparticles, lipid nanocapsules, nanostructured lipid carriers, and drug-lipid conjugates are all examples of how it can be possible to combine the properties of the more acknowledged liposomal systems, such as biocompatibility and biodegradability, with the stability and compositional flexibility, distinctive of polymeric nanosystems. This article introduces recent patents, filed in years 2007-2013, that deal with novel or amended methods of production of the various types of lipid-based nanocarriers. Although a significant gap still remains between basic research and patenting activity in this field, many of the proposed methods can attain an industrial value. Furthermore, the critical analysis of these patents further supports the position that a general revision of patenting systems at an international level would be necessary for nanosized pharmaceutical systems. PMID:24237173

  16. Cell-Specific Promoters Enable Lipid-Based Nanoparticles to Deliver Genes to Specific Cells of the Retina In Vivo

    PubMed Central

    Wang, Yuhong; Rajala, Ammaji; Cao, Binrui; Ranjo-Bishop, Michelle; Agbaga, Martin-Paul; Mao, Chuanbin; Rajala, Raju V.S.

    2016-01-01

    Non-viral vectors, such as lipid-based nanoparticles (liposome-protamine-DNA complex [LPD]), could be used to deliver a functional gene to the retina to correct visual function and treat blindness. However, one of the limitations of LPD is the lack of cell specificity, as the retina is composed of seven types of cells. If the same gene is expressed in multiple cell types or is absent from one desired cell type, LPD-mediated gene delivery to every cell may have off-target effects. To circumvent this problem, we have tested LPD-mediated gene delivery using various generalized, modified, and retinal cell-specific promoters. We achieved retinal pigment epithelium cell specificity with vitelliform macular dystrophy (VMD2), rod cell specificity with mouse rhodopsin, cone cell specificity with red/green opsin, and ganglion cell specificity with thymocyte antigen promoters. Here we show for the first time that cell-specific promoters enable lipid-based nanoparticles to deliver genes to specific cells of the retina in vivo. This work will inspire investigators in the field of lipid nanotechnology to couple cell-specific promoters to drive expression in a cell- and tissue-specific manner. PMID:27446487

  17. Drug-excipient complexation in lipid based delivery systems: an investigation of the Tipranavir-1,3-dioctanolyglycerol complex.

    PubMed

    Chen, Shirlynn; Dudhedia, Mayur S; Wang, Zeren; Darrington, Richard T; Tamblyn, Toby; Smoliga, John A; Jones, Paul-James; Krill, Steven L

    2009-05-01

    This report describes the solubility properties of a poorly soluble drug-excipient complex in a lipid based formulation. Tipranavir (TPV) was used as the model drug and 1,3-dioctanoylglycerol (DOG) as the excipient. The TPV-DOG complex was prepared by dissolving TPV and DOG in ethanol at 60 degrees C followed by evaporation of ethanol. The formation of the complex with a 4:1 TPV-to-DOG molar ratio was confirmed by XRPD, DSC, and NMR. At 25 degrees C, total solubility of TPV decreased with increasing DOG concentration. The solubility properties of the TPV-DOG complex can be described by two simultaneous equilibria: a liquid-solid phase equilibrium of the complex and a species equilibrium among the various species in the liquid phase. A model equation was derived accordingly with two parameters, the intrinsic solubility of the complex (S(o)), and the solution complex constant (K(41)). The model was in good agreement with experimental results. The values of S(o) and K(41) are 0.0186 +/- 0.0025 (M) and 21.97 +/- 7.19 (1/M(4)), respectively. The equation can successfully predict the concentrations of total and free TPV as a function of DOG in the formulation. The approach developed provides a useful tool for rationale selection of excipients and their levels to avoid drug precipitation in lipid based formulations.

  18. Cell-Specific Promoters Enable Lipid-Based Nanoparticles to Deliver Genes to Specific Cells of the Retina In Vivo.

    PubMed

    Wang, Yuhong; Rajala, Ammaji; Cao, Binrui; Ranjo-Bishop, Michelle; Agbaga, Martin-Paul; Mao, Chuanbin; Rajala, Raju V S

    2016-01-01

    Non-viral vectors, such as lipid-based nanoparticles (liposome-protamine-DNA complex [LPD]), could be used to deliver a functional gene to the retina to correct visual function and treat blindness. However, one of the limitations of LPD is the lack of cell specificity, as the retina is composed of seven types of cells. If the same gene is expressed in multiple cell types or is absent from one desired cell type, LPD-mediated gene delivery to every cell may have off-target effects. To circumvent this problem, we have tested LPD-mediated gene delivery using various generalized, modified, and retinal cell-specific promoters. We achieved retinal pigment epithelium cell specificity with vitelliform macular dystrophy (VMD2), rod cell specificity with mouse rhodopsin, cone cell specificity with red/green opsin, and ganglion cell specificity with thymocyte antigen promoters. Here we show for the first time that cell-specific promoters enable lipid-based nanoparticles to deliver genes to specific cells of the retina in vivo. This work will inspire investigators in the field of lipid nanotechnology to couple cell-specific promoters to drive expression in a cell- and tissue-specific manner. PMID:27446487

  19. Transductional instability of Tn5-induced mutations: generalized and specialized transduction of Tn5 by bacteriophage P1.

    PubMed

    Berg, C M; Grullón, C A; Wang, A; Whalen, W A; Berg, D E

    1983-10-01

    Generalized transduction is commonly used to move transposon-induced mutations among bacterial strains by selecting for inheritance of a transposon-encoded resistance determinant. Although complete cotransduction of the resistance determinant and the chromosomal mutation might be expected, it is often found that when Tn5(Kan) insertion mutations are transduced by bacteriophage P1 most of the nonmutant kanamycin-resistant transductants area due to specialized transduction of Tn5. Such P1::Tn5 specialized transducing phage are not found when a mutant Tn5 element lacking a functional transposase is employed.

  20. The transduction properties of intercostal muscle mechanoreceptors

    PubMed Central

    Holt, Gregory A; Johnson, Richard D; Davenport, Paul W

    2002-01-01

    Background Intercostal muscles are richly innervated by mechanoreceptors. In vivo studies of cat intercostal muscle have shown that there are 3 populations of intercostal muscle mechanoreceptors: primary muscle spindles (1°), secondary muscle spindles (2°) and Golgi tendon organs (GTO). The purpose of this study was to determine the mechanical transduction properties of intercostal muscle mechanoreceptors in response to controlled length and velocity displacements of the intercostal space. Mechanoreceptors, recorded from dorsal root fibers, were localized within an isolated intercostal muscle space (ICS). Changes in ICS displacement and the velocity of ICS displacement were independently controlled with an electromagnetic motor. ICS velocity (0.5 – 100 μm/msec to a displacement of 2,000 μm) and displacement (50–2,000 μm at a constant velocity of 10 μm/msec) parameters encompassed the full range of rib motion. Results Both 1° and 2° muscle spindles were found evenly distributed within the ICS. GTOs were localized along the rib borders. The 1° spindles had the greatest discharge frequency in response to displacement amplitude followed by the 2° afferents and GTOs. The 1° muscle spindles also possessed the greatest discharge frequency in response to graded velocity changes, 3.0 spikes·sec-1/μm·msec-1. GTOs had a velocity response of 2.4 spikes·sec-1/μm·msec-1 followed by 2° muscle spindles at 0.6 spikes·sec-1/μm·msec-1. Conclusion The results of this study provide a systematic description of the mechanosenitivity of the 3 types of intercostal muscle mechanoreceptors. These mechanoreceptors have discharge properties that transduce the magnitude and velocity of intercostal muscle length. PMID:12392601

  1. Gravitational sensory transduction chain in flagellates

    NASA Astrophysics Data System (ADS)

    Häder, D.-P.; Richter, P.; Ntefidou, M.; Lebert, M.

    Earlier hypotheses have assumed that gravitactic orientation in flagellates, such as the photosynthetic unicell Euglena gracilis, is brought about by passive alignment of the cells in the water column by being tail heavy. A recent experiment on a sounding rocket (TEXUS 40) comparing immobilized cells with mobile cells demonstrated that the passive buoy effect can account for approximately 20% of the orientation of the cells in a gravity field. The cells show either positive or negative gravitaxis depending on other external or internal factors. Shortly after inoculation, the tendency of young cells to swim downward in the water column can be readily reverted by adding micromolar concentrations of some heavy metal ions including copper, cadmium or lead. The negative gravitaxis of older cells is converted into a positive one by stress factors such as increasing salinity or exposure to excessive visible or UV radiation. The mechanism for this switch seems to involve reactive oxygen species since the gravitactic sign change was suppressed when oxygen was removed by flushing the cell suspension with nitrogen. Also, the addition of radical scavengers (Trolox, ascorbic acid or potassium cyanide) abolished or reduced the gravitactic sign change. Addition of hydrogen peroxide induced a gravitactic sign change in the absence of external stress factors. The primary reception for the gravity vector seems to involve mechanosensitive ion channels which specifically gate calcium ions inward. We have identified several gene sequences for putative mechanosensory channels in Euglena and have applied RNAi to identify which of these channels are involved in graviperception. The influx of Ca 2+ activates calmodulin (CaM) which has been shown to be involved in the sensory transduction chain of graviorientation. It is known that an adenylyl cyclase is bound to the flagellar membrane in Euglena which is activated by CaM. This enzyme produces cAMP which has also been shown to be the key

  2. The sensory transduction pathways in bacterial chemotaxis

    NASA Technical Reports Server (NTRS)

    Taylor, Barry L.

    1989-01-01

    Bacterial chemotaxis is a useful model for investigating in molecular detail the behavioral response of cells to changes in their environment. Peritrichously flagellated bacteria such as coli and typhimurium swim by rotating helical flagella in a counterclockwise direction. If flagellar rotation is briefly reversed, the bacteria tumble and change the direction of swimming. The bacteria continuously sample the environment and use a temporal sensing mechanism to compare the present and immediate past environments. Bacteria respond to a broad range of stimuli including changes in temperature, oxygen concentration, pH and osmotic strength. Bacteria are attracted to potential sources of nutrition such as sugars and amino acids and are repelled by other chemicals. In the methylation-dependent pathways for sensory transduction and adaptation in E. coli and S. typhimurium, chemoeffectors bind to transducing proteins that span the plasma membrane. The transducing proteins are postulated to control the rate of autophosphorylation of the CheA protein, which in turn phosphorylates the CheY protein. The phospho-CheY protein binds to the switch on the flagellar motor and is the signal for clockwise rotation of the motor. Adaptation to an attractant is achieved by increasing methylation of the transducing protein until the attractant stimulus is cancelled. Responses to oxygen and certain sugars involve methylation-independent pathways in which adaption occurs without methylation of a transducing protein. Taxis toward oxygen is mediated by the electron transport system and changes in the proton motive force. Recent studies have shown that the methylation-independent pathway converges with the methylation-dependent pathway at or before the CheA protein.

  3. Signal transduction in the footsteps of goethe and schiller.

    PubMed

    Friedrich, Karlheinz; Lindquist, Jonathan A; Entschladen, Frank; Serfling, Edgar; Thiel, Gerald; Kieser, Arnd; Giehl, Klaudia; Ehrhardt, Christina; Feller, Stephan M; Ullrich, Oliver; Schaper, Fred; Janssen, Ottmar; Hass, Ralf

    2009-02-04

    The historical town of Weimar in Thuringia, the "green heart of Germany" was the sphere of Goethe and Schiller, the two most famous representatives of German literature's classic era. Not yet entirely as influential as those two cultural icons, the Signal Transduction Society (STS) has nevertheless in the last decade established within the walls of Weimar an annual interdisciplinary Meeting on "Signal Transduction - Receptors, Mediators and Genes", which is well recognized as a most attractive opportunity to exchange results and ideas in the field.The 12th STS Meeting was held from October 28 to 31 and provided a state-of-the-art overview of various areas of signal transduction research in which progress is fast and discussion lively. This report is intended to share with the readers of CCS some highlights of the Meeting Workshops devoted to specific aspects of signal transduction.

  4. Bacteriophage Transduction in Staphylococcus aureus: Broth-Based Method.

    PubMed

    Krausz, Kelsey L; Bose, Jeffrey L

    2016-01-01

    The ability to move DNA between Staphylococcus strains is essential for the genetic manipulation of this bacterium. Often in the Staphylococci, this is accomplished through transduction using generalized transducing phage and can be performed in different ways and therefore the presence of two transduction procedures in this book. The following protocol is a relatively easy-to-perform, broth-based procedure that we have used extensively to move both plasmids and chromosomal fragments between strains of Staphylococcus aureus.

  5. Transforming lipid-based oral drug delivery systems into solid dosage forms: an overview of solid carriers, physicochemical properties, and biopharmaceutical performance.

    PubMed

    Tan, Angel; Rao, Shasha; Prestidge, Clive A

    2013-12-01

    The diversity of lipid excipients available commercially has enabled versatile formulation design of lipid-based drug delivery systems for enhancing the oral absorption of poorly water-soluble drugs, such as emulsions, microemulsions, micelles, liposomes, niosomes and various self-emulsifying systems. The transformation of liquid lipid-based systems into solid dosage forms has been investigated for several decades, and has recently become a core subject of pharmaceutical research as solidification is regarded as viable means for stabilising lipid colloidal systems while eliminating stringent processing requirements associated with liquid systems. This review describes the types of pharmaceutical grade excipients (silica nanoparticle/microparticle, polysaccharide, polymer and protein-based materials) used as solid carriers and the current state of knowledge on the liquid-to-solid conversion approaches. Details are primarily focused on the solid-state physicochemical properties and redispersion capacity of various dry lipid-based formulations, and how these relate to the in vitro drug release and solubilisation, lipid carrier digestion and cell permeation performances. Numerous in vivo proof-of-concept studies are presented to highlight the viability of these dry lipid-based formulations. This review is significant in directing future research work in fostering translation of dry lipid-based formulations into clinical applications. PMID:23775443

  6. Mechanical basis of osmosensory transduction in magnocellular neurosecretory neurones of the rat supraoptic nucleus.

    PubMed

    Prager-Khoutorsky, M; Bourque, C W

    2015-06-01

    Rat magnocellular neurosecretory cells (MNCs) release vasopressin and oxytocin to promote antidiuresis and natriuresis at the kidney. The osmotic control of oxytocin and vasopressin release at the neurohypophysis is required for osmoregulation in these animals, and this release is mediated by a modulation of the action potential firing rate by the MNCs. Under basal (isotonic) conditions, MNCs fire action potentials at a slow rate, and this activity is inhibited by hypo-osmotic conditions and enhanced by hypertonicity. The effects of changes in osmolality on MNCs are mediated by a number of different factors, including the involvement of synaptic inputs, the release of taurine by local glial cells and regulation of ion channels expressed within the neurosecretory neurones themselves. We review recent findings that have clarified our understanding of how osmotic stimuli modulate the activity of nonselective cation channels in MNCs. Previous studies have shown that osmotically-evoked changes in membrane potential and action potential firing rate in acutely isolated MNCs are provoked mainly by a modulation of nonselective cation channels. Notably, the excitation of isolated MNCs during hypertonicity is mediated by the activation of a capsaicin-insensitive cation channel that MNCs express as an N-terminal variant of the transient receptor potential vanilloid 1 (Trpv1) channel. The activation of this channel during hypertonicity is a mechanical process associated with cell shrinking. The effectiveness of this mechanical process depends on the presence of a thin layer of actin filaments (F-actin) beneath the plasma membrane, as well as a densely interweaved network of microtubules (MTs) occupying the bulk of the cytoplasm of MNCs. Although the mechanism by which F-actin contributes to Trpv1 activation remains unknown, recent data have shown that MTs interact with Trpv1 channels via binding sites on the C-terminus, and that the force mediated through this complex is

  7. Modeling Signal Transduction and Lipid Rafts in Immune Cells

    NASA Astrophysics Data System (ADS)

    Prasad, Ashok

    2011-03-01

    Experimental evidence increasingly suggests that lipid rafts are nanometer sized cholesterol dependent dynamic assemblies enriched in sphingolipids and associated proteins. Lipid rafts are dynamic structures that break-up and reform on a relatively short time-scale, and are believed to facilitate the interactions of raft-associated proteins. The role of these rafts in signaling has been controversial, partly due to controversies regarding the existence and nature of the rafts themselves. Experimental evidence has indicated that in several cell types, especially T cells, rafts do influence signal transduction and T cell activation. Given the emerging consensus on the biophysical character of lipid rafts, the question can be asked as to what roles they possibly play in signal transduction. Here we carry out simulations of minimal models of the signal transduction network that regulates Src-family kinase dynamics in T cells and other cell types. By separately treating raft-based biochemical interactions, we find that rafts can indeed putatively play an important role in signal transduction, and in particular may affect the sensitivity of signal transduction. This illuminates possible functional consequences of membrane heterogeneities on signal transduction and points towards mechanisms for spatial control of signaling by cells.

  8. Engineering key components in a synthetic eukaryotic signal transduction pathway

    PubMed Central

    Antunes, Mauricio S; Morey, Kevin J; Tewari-Singh, Neera; Bowen, Tessa A; Smith, J Jeff; Webb, Colleen T; Hellinga, Homme W; Medford, June I

    2009-01-01

    Signal transduction underlies how living organisms detect and respond to stimuli. A goal of synthetic biology is to rewire natural signal transduction systems. Bacteria, yeast, and plants sense environmental aspects through conserved histidine kinase (HK) signal transduction systems. HK protein components are typically comprised of multiple, relatively modular, and conserved domains. Phosphate transfer between these components may exhibit considerable cross talk between the otherwise apparently linear pathways, thereby establishing networks that integrate multiple signals. We show that sequence conservation and cross talk can extend across kingdoms and can be exploited to produce a synthetic plant signal transduction system. In response to HK cross talk, heterologously expressed bacterial response regulators, PhoB and OmpR, translocate to the nucleus on HK activation. Using this discovery, combined with modification of PhoB (PhoB-VP64), we produced a key component of a eukaryotic synthetic signal transduction pathway. In response to exogenous cytokinin, PhoB-VP64 translocates to the nucleus, binds a synthetic PlantPho promoter, and activates gene expression. These results show that conserved-signaling components can be used across kingdoms and adapted to produce synthetic eukaryotic signal transduction pathways. PMID:19455134

  9. Transformation of poorly water-soluble drugs into lipophilic ionic liquids enhances oral drug exposure from lipid based formulations.

    PubMed

    Sahbaz, Yasemin; Williams, Hywel D; Nguyen, Tri-Hung; Saunders, Jessica; Ford, Leigh; Charman, Susan A; Scammells, Peter J; Porter, Christopher J H

    2015-06-01

    Absorption after oral administration is a requirement for almost all drug products but is a challenge for drugs with intrinsically low water solubility. Here, the weakly basic, poorly water-soluble drugs (PWSDs) itraconazole, cinnarizine, and halofantrine were converted into lipophilic ionic liquids to facilitate incorporation into lipid-based formulations and integration into lipid absorption pathways. Ionic liquids were formed via metathesis reactions of the hydrochloride salt of the PWSDs with a range of lipophilic counterions. The resultant active pharmaceutical ingredient-ionic liquids (API-ILs) were liquids or low melting point solids and either completely miscible or highly soluble in lipid based, self-emulsifying drug delivery systems (SEDDS) comprising mixtures of long or medium chain glycerides, surfactants such as Kolliphor-EL and cosolvents such as ethanol. They also readily incorporated into the colloids formed in intestinal fluids during lipid digestion. Itraconazole docusate or cinnarizine decylsulfate API-ILs were subsequently dissolved in long chain lipid SEDDS at high concentration, administered to rats and in vivo exposure assessed. The data were compared to control formulations based on the same SEDDS formulations containing the same concentrations of drug as the free base, but in this case as a suspension (since the solubility of the free base in the SEDDS was much lower than the API-ILs). For itraconazole, comparison was also made to a physical mixture of itraconazole free base and sodium docusate in the same SEDDS formulation. For both drugs plasma exposure was significantly higher for the API-IL containing formulations (2-fold for cinnarizine and 20-fold for itraconazole), when compared to the suspension formulations (or the physical mixture in the case of itraconazole) at the same dose. The liquid SEDDS formulations, made possible by the use of the API-ILs, also provide advantages in dose uniformity, capsule filling, and stability compared

  10. Lipid-based nanosystems for CD44 targeting in cancer treatment: recent significant advances, ongoing challenges and unmet needs.

    PubMed

    Nascimento, Thais Leite; Hillaireau, Hervé; Vergnaud, Juliette; Fattal, Elias

    2016-07-01

    Extensive experimental evidence demonstrates the important role of hyaluronic acid (HA)-CD44 interaction in cell proliferation and migration, inflammation and tumor growth. Taking advantage of this interaction, the design of HA-modified nanocarriers has been investigated for targeting CD44-overexpressing cells with the purpose of delivering drugs to cancer or inflammatory cells. The effect of such modification on targeting efficacy is influenced by several factors. In this review, we focus on the impact of HA-modification on the characteristics of lipid-based nanoparticles. We try to understand how these modifications influence particle physicochemical properties, interaction with CD44 receptors, intracellular trafficking pathways, toxicity, complement/macrophage activation and pharmacokinetics. Our aim is to provide insight in tailoring particle modification by HA in order to design more efficient CD44-targeting lipid nanocarriers.

  11. Phase Transitions of Isotropic to Anisotropic Biocompatible Lipid-Based Drug Delivery Systems Overcoming Insoluble Benznidazole Loading.

    PubMed

    Streck, Letícia; Sarmento, Víctor H V; Machado, Paula R L; Farias, Kleber J S; Fernandes-Pedrosa, Matheus F; da Silva-Júnior, Arnóbio Antônio

    2016-01-01

    Previous studies reported low benznidazole (BNZ) loading in conventional emulsions due to the weak interaction of the drug with the most common oils used to produce foods or pharmaceuticals. In this study, we focused on how the type of surfactant, surfactant-to-oil ratio w/w (SOR) and oil-to-water ratio w/w (OWR) change the phase behavior of different lipid-based drug delivery systems (LBDDS) produced by emulsion phase inversion. The surfactant mixture composed of soy phosphatidylcholine and sodium oleate (1:7, w/w, hydrophilic lipophilic balance = 16) stabilized medium chain triglyceride in water. Ten formulations with the clear aspect or less turbid dispersions (five with the SOR ranging from 0.5 to 2.5 and five with the OWR from 0.06 to 0.4) were selected from the phase behavior diagram to assess structural features and drug-loading capacity. The rise in the SOR induced the formation of distinct lipid-based drug delivery systems (nanoemulsions and liquid crystal lamellar type) that were identified using rheological measurements and cross-polarized light microscopy images. Clear dispersions of small and narrow droplet-sized liquid-like nanoemulsions, Newtonian flow-type, were produced at SOR from 0.5 to 1.5 and OWR from 0.12 to 0.4, while clear liquid or gel-like liquid crystals were produced at SOR from 1.5 to 2.5. The BNZ loading was improved according to the composition and type of LBDDS produced, suggesting possible drug location among surfactant layers. The cell viability assays proved the biocompatibility for all of the prepared nanoemulsions at SOR less than 1.5 and liquid crystals at SOR less than 2.5, demonstrating their promising features for the oral or parenteral colloidal delivery systems containing benznidazole for Chagas disease treatment. PMID:27376278

  12. Formulation and physiological and biopharmaceutical issues in the development of oral lipid-based drug delivery systems.

    PubMed

    Wasan, K M

    2001-04-01

    The rapidly increasing availability of drug receptor structural characteristics has permitted the receptor-guided synthesis of potential new drug molecules. This synthesis strategy frequently results in the creation of polycyclic and highly hydrophobic compounds, with attendant poor oral bioavailability resulting from low solubility and slow dissolution rate in the primarily aqueous contents of the gastrointestinal (GI) tract. In an attempt to improve the solubility-limited bioavailabiliy associated with these compounds, formulators have turned to the use of lipid excipients in which the compounds can be solubilized prior to oral administration. This new class of excipients presents the pharmaceutical scientist with a number of new challenges at all stages of the formulation development process, beginning with the excipient selection and stability assessment of the prototype formulation, up to and including scale-up and mass production of the final market-image product. The interaction of lipid-based formulations with the gastrointestinal system and associated digestive processes presents additional challenges and opportunities that will be understood more fully as we begin to unravel the intricacies of the GI processing of lipid excipients. For example, an increasing body of evidence has shown that certain lipids are capable of inhibiting both presystemic drug metabolism and drug efflux by the gut wall mediated by p-glycoprotein (PGP). And, it is well known that lipids are capable of enhancing lymphatic transport of hydrophobic drugs, thereby reducing drug clearance resulting from hepatic first-pass metabolism. This review addresses the current state of knowledge regarding oral lipid-based formulation development and scale-up issues and the physiological and biopharmaceutical aspects pertinent to the development of an orally bioavailable and efficacious dosage form.

  13. Phase Transitions of Isotropic to Anisotropic Biocompatible Lipid-Based Drug Delivery Systems Overcoming Insoluble Benznidazole Loading

    PubMed Central

    Streck, Letícia; Sarmento, Víctor H. V.; Machado, Paula R. L.; Farias, Kleber J. S.; Fernandes-Pedrosa, Matheus F.; da Silva-Júnior, Arnóbio Antônio

    2016-01-01

    Previous studies reported low benznidazole (BNZ) loading in conventional emulsions due to the weak interaction of the drug with the most common oils used to produce foods or pharmaceuticals. In this study, we focused on how the type of surfactant, surfactant-to-oil ratio w/w (SOR) and oil-to-water ratio w/w (OWR) change the phase behavior of different lipid-based drug delivery systems (LBDDS) produced by emulsion phase inversion. The surfactant mixture composed of soy phosphatidylcholine and sodium oleate (1:7, w/w, hydrophilic lipophilic balance = 16) stabilized medium chain triglyceride in water. Ten formulations with the clear aspect or less turbid dispersions (five with the SOR ranging from 0.5 to 2.5 and five with the OWR from 0.06 to 0.4) were selected from the phase behavior diagram to assess structural features and drug-loading capacity. The rise in the SOR induced the formation of distinct lipid-based drug delivery systems (nanoemulsions and liquid crystal lamellar type) that were identified using rheological measurements and cross-polarized light microscopy images. Clear dispersions of small and narrow droplet-sized liquid-like nanoemulsions, Newtonian flow-type, were produced at SOR from 0.5 to 1.5 and OWR from 0.12 to 0.4, while clear liquid or gel-like liquid crystals were produced at SOR from 1.5 to 2.5. The BNZ loading was improved according to the composition and type of LBDDS produced, suggesting possible drug location among surfactant layers. The cell viability assays proved the biocompatibility for all of the prepared nanoemulsions at SOR less than 1.5 and liquid crystals at SOR less than 2.5, demonstrating their promising features for the oral or parenteral colloidal delivery systems containing benznidazole for Chagas disease treatment. PMID:27376278

  14. Phase Transitions of Isotropic to Anisotropic Biocompatible Lipid-Based Drug Delivery Systems Overcoming Insoluble Benznidazole Loading.

    PubMed

    Streck, Letícia; Sarmento, Víctor H V; Machado, Paula R L; Farias, Kleber J S; Fernandes-Pedrosa, Matheus F; da Silva-Júnior, Arnóbio Antônio

    2016-01-01

    Previous studies reported low benznidazole (BNZ) loading in conventional emulsions due to the weak interaction of the drug with the most common oils used to produce foods or pharmaceuticals. In this study, we focused on how the type of surfactant, surfactant-to-oil ratio w/w (SOR) and oil-to-water ratio w/w (OWR) change the phase behavior of different lipid-based drug delivery systems (LBDDS) produced by emulsion phase inversion. The surfactant mixture composed of soy phosphatidylcholine and sodium oleate (1:7, w/w, hydrophilic lipophilic balance = 16) stabilized medium chain triglyceride in water. Ten formulations with the clear aspect or less turbid dispersions (five with the SOR ranging from 0.5 to 2.5 and five with the OWR from 0.06 to 0.4) were selected from the phase behavior diagram to assess structural features and drug-loading capacity. The rise in the SOR induced the formation of distinct lipid-based drug delivery systems (nanoemulsions and liquid crystal lamellar type) that were identified using rheological measurements and cross-polarized light microscopy images. Clear dispersions of small and narrow droplet-sized liquid-like nanoemulsions, Newtonian flow-type, were produced at SOR from 0.5 to 1.5 and OWR from 0.12 to 0.4, while clear liquid or gel-like liquid crystals were produced at SOR from 1.5 to 2.5. The BNZ loading was improved according to the composition and type of LBDDS produced, suggesting possible drug location among surfactant layers. The cell viability assays proved the biocompatibility for all of the prepared nanoemulsions at SOR less than 1.5 and liquid crystals at SOR less than 2.5, demonstrating their promising features for the oral or parenteral colloidal delivery systems containing benznidazole for Chagas disease treatment.

  15. EDITORIAL: Special section on signal transduction Special section on signal transduction

    NASA Astrophysics Data System (ADS)

    Shvartsman, Stanislav

    2012-08-01

    This special section of Physical Biology focuses on multiple aspects of signal transduction, broadly defined as the study of the mechanisms by which cells communicate with their environment. Mechanisms of cell communication involve detection of incoming signals, which can be chemical, mechanical or electromagnetic, relaying these signals to intracellular processes, such as cytoskeletal networks or gene expression systems, and, ultimately, converting these signals to responses such as cell differentiation or death. Given the multiscale nature of signal transduction systems, they must be studied at multiple levels, from the identities and structures of molecules comprising signal detection and interpretation networks, to the systems-level properties of these networks. The 11 papers in this special section illustrate some of the most exciting aspects of signal transduction research. The first two papers, by Marie-Anne Félix [1] and by Efrat Oron and Natalia Ivanova [2], focus on cell-cell interactions in developing tissues, using vulval patterning in worm and cell fate specification in mammalian embryos as prime examples of emergent cell behaviors. Next come two papers from the groups of Julio Saez-Rodriguez [3] and Kevin Janes [4]. These papers discuss how the causal relationships between multiple components of signaling systems can be inferred using multivariable statistical analysis of empirical data. An authoritative review by Zarnitsyna and Zhu [5] presents a detailed discussion of the sequence of signaling events involved in T-cell triggering. Once the structure and components of the signaling systems are determined, they can be modeled using approaches that have been successful in other physical sciences. As two examples of such approaches, reviews by Rubinstein [6] and Kholodenko [7], present reaction-diffusion models of cell polarization and thermodynamics-based models of gene regulation. An important class of models takes the form of enzymatic networks

  16. Cationic surfactants based on ferrocene

    SciTech Connect

    Pankratov, V.A.; Kucherova, N.L.; Abramzon, A.A.

    1988-07-20

    Quaternary ammonium salts based on ferrocene were synthesized and their surface active properties were studied as potential cationic surfactants and for uses including antiknock compounds. The salts were halide and nitrate derivatives of dimethylferrocenylmethylammonium and were prepared by aminomethylation of ferrocene. Chemical reaction yields, melting points, surface tension isotherms, and other characteristics were assessed.

  17. Reciprocity and gyrotropism in magnetic resonance transduction

    SciTech Connect

    Tropp, James

    2006-12-15

    We give formulas for transduction in magnetic resonance - i.e., the appearance of an emf due to Larmor precession of spins - based upon the modified Lorentz reciprocity principle for gyrotropic (also called 'nonreciprocal') media, i.e., in which a susceptibility tensor is carried to its transpose by reversal of an external static field [cf., R. F. Harrington and A. T. Villeneuve IRE Trans. Microwave Theory and Technique MTT6, 308 (1958)]. Prior applications of reciprocity to magnetic resonance, despite much success, have ignored the gyrotropism which necessarily arises due to nuclear and/or unpaired electronic spins. For detection with linearly polarized fields, oscillating at the Larmor frequency, the emf is written in terms of a volume integral containing a product of two factors which we define as the antenna patterns, i.e. (H{sub 1x}{+-}iH{sub 1y}), where, e.g., for a single transceive antenna, the H's are just the spatially dependent oscillatory magnetic field strengths, per the application of some reference current at the antenna terminals, with the negative sign obtaining for transmission, and the positive for reception. Similar expressions hold for separate transmit and receive antennas; expressions are also given for circular polarization of the fields. We then exhibit a receive-only array antenna of two elements for magnetic resonance imaging of protons, which, due an intensity artifact arising from stray reactive coupling of the elements, produces, despite its own bilateral symmetry, asymmetric proton NMR images of a symmetric cylindrical phantom containing aqueous saline solution [J. Tropp and T. Schirmer, J. Magn. Reson. 151, 146 (2001)]. Modification of this two-port antenna, to function in transmit-receive mode, allows us to demonstrate highly nonreciprocal behavior: that is, to record images (of cylindrical test phantoms containing aqueous saline solution) whose appearance dramatically changes, when the roles of transmission and reception are

  18. Arene-thioether mixed complex radical cations

    SciTech Connect

    Werst, D.W.

    1994-03-01

    Studies of radiolytically generated radical cations in aromatic hydrocarbon solvents have led to the first direct characterization of monomeric thioether radical cations in liquid solution. Observation of these very reactive chemical intermediates is made possible by the great sensitivity of fluorescence-detected magnetic resonance (FDMR) and by solvent stabilization of the thioether radical cations via electron donation. Monomeric thioether radical cations in arene solvents such as toluene exist as arene-thioether mixed complex radical cations -- the first {pi}-lone pair mixed complex radical cations ever observed. Such orbital interactions are of fundamental importance for open-shell intermediates as they have consequences for both electronic structure and reactivity. Thioether radical cations provide a valuable test system to probe the chemical influence of orbital interactions that are generic to all {pi}-type and heteroatom-containing organic radical cations, and magnetic resonance provides unsurpassed structural resolution for condensed-phase paramagnetic intermediates.

  19. Halogenated silanes, radicals, and cations

    NASA Astrophysics Data System (ADS)

    Wang, Liming; He, Yi-Liang

    2008-09-01

    Quantum chemistry study has been carried out on the structure and energetics of halogenated silanes, radicals, and cations (SiHxXy0,+1, X = F, Cl, Br; x + y = 1-4). The geometries are optimized at B3LYP/6-31+G(2df,p) level. The adiabatic ionization energiess (IEas), relative energetics of cations, proton affinities (PAs) of silanes, and the enthalpies of formation are predicted using G3(CC) model chemistry. Non-classical ion complex structures are found for hydrogenated cations and transition states connecting classical and non-classical structures are also located. The most stable cations for silylene and silyl radicals have their classical divalent and trivalent structures, and those for silanes have non-classical structures except for SiH3Br+ and SiH2Br2+. The non-classical structures for halosilane cations imply difficulty in experimentally measurement of the adiabatic ionization energies using photoionization or photoelectron studies. For SiH3X, SiH2X2, and SiHX3, the G3(CC) adiabatic IEas to classical ionic structures closest to their neutrals agree better with the photoelectron spectroscopic measurements. The transition states between classical and non-classical structures also hamper the photoionization determination of the appearance energies for silylene cations from silanes. The G3(CC) results for SiHx0,+1 agree excellently with the photoionization mass spectrometric study, and the results for fluorinated and chlorinated species also agree with the previous theoretical predictions at correlation levels from BAC-MP4 to CCSD(T)/CBS. The predicted enthalpy differences between SiH2Cl+, SiHCl2+, and SiCl3+ are also in accordance with previous kinetics study. The G3(CC) results show large discrepancies to the collision-induced charge transfer and/or dissociation reactions involving SiFx+ and SiClx+ ions, for which the G3(CC) enthalpies of formation are also significantly differed from the previous theoretical predictions, especially on SiFx+ (x = 2-4). The G3

  20. Nonselective block by La3+ of Arabidopsis ion channels involved in signal transduction

    NASA Technical Reports Server (NTRS)

    Lewis, B. D.; Spalding, E. P.; Evans, M. L. (Principal Investigator)

    1998-01-01

    Lanthanide ions such as La3+ are frequently used as blockers to test the involvement of calcium channels in plant and animal signal transduction pathways. For example, the large rise in cytoplasmic Ca2+ concentration triggered by cold shock in Arabidopsis seedlings is effectively blocked by 10 mM La3+ and we show here that the simultaneous large membrane depolarization is similarly blocked. However, a pharmacological tool is only as useful as it is selective and the specificity of La3+ for calcium channels was brought into question by our finding that it also blocked a blue light (BL)-induced depolarization that results from anion channel activation and believed not to involve calcium channels. This unexpected inhibitory effect of La3+ on the BL-induced depolarization is explained by our finding that 10 mM La3+ directly and completely blocked the BL-activated anion channel when applied to excised patches. We have investigated the ability of La3+ to block noncalcium channels in Arabidopsis. In addition to the BL-activated anion channel, 10 mM La3+ blocked a cation channel and a stretch-activated channel in patches of plasma membrane excised from hypocotyl cells. In root cells, 10 mM La3+ inhibited the activity of an outward-rectifying potassium channel at the whole cell and single-channel level by 47% and 58%, respectively. We conclude that La3+ is a nonspecific blocker of multiple ionic conductances in Arabidopsis and may disrupt signal transduction processes independently of any effect on Ca2+ channels.

  1. Nonreciprocal Radio Frequency Transduction in a Parametric Mechanical Artificial Lattice

    NASA Astrophysics Data System (ADS)

    Huang, Pu; Zhang, Liang; Zhou, Jingwei; Tian, Tian; Yin, Peiran; Duan, Changkui; Du, Jiangfeng

    2016-07-01

    Generating nonreciprocal radio frequency transduction plays important roles in a wide range of research and applications, and an aspiration is to integrate this functionality into microcircuits without introducing a magnetic field, which, however, remains challenging. By designing a 1D artificial lattice structure with a neighbor interaction engineered parametrically, we predicted a nonreciprocity transduction with a large unidirectionality. We then experimentally demonstrated the phenomenon on a nanoelectromechanical chip fabricated by conventional complementary metal-silicon processing. A unidirectionality with isolation as high as 24 dB is achieved, and several different transduction schemes are realized by programing the control voltage topology. Apart from being used as a radio frequency isolator, the system provides a way to build a practical on-chip programmable device for broad research and applications in the radio frequency domain.

  2. Nonreciprocal Radio Frequency Transduction in a Parametric Mechanical Artificial Lattice.

    PubMed

    Huang, Pu; Zhang, Liang; Zhou, Jingwei; Tian, Tian; Yin, Peiran; Duan, Changkui; Du, Jiangfeng

    2016-07-01

    Generating nonreciprocal radio frequency transduction plays important roles in a wide range of research and applications, and an aspiration is to integrate this functionality into microcircuits without introducing a magnetic field, which, however, remains challenging. By designing a 1D artificial lattice structure with a neighbor interaction engineered parametrically, we predicted a nonreciprocity transduction with a large unidirectionality. We then experimentally demonstrated the phenomenon on a nanoelectromechanical chip fabricated by conventional complementary metal-silicon processing. A unidirectionality with isolation as high as 24 dB is achieved, and several different transduction schemes are realized by programing the control voltage topology. Apart from being used as a radio frequency isolator, the system provides a way to build a practical on-chip programmable device for broad research and applications in the radio frequency domain. PMID:27419591

  3. Signal Transduction in Histidine Kinases: Insights from New Structures

    PubMed Central

    Bhate, Manasi P.; Molnar, Kathleen S.; Goulian, Mark; DeGrado, William F.

    2015-01-01

    Histidine kinases (HKs) are major players in bacterial signaling. There has been an explosion of new HK crystal structures in the last five years. We globally analyze the structures of HKs to yield insights into the mechanisms by which signals are transmitted to and across protein structures in this family. We interpret known enzymological data in the context of new structural data to show how asymmetry across the dimer interface is a key feature of signal transduction in HKs, and discuss how different HK domains undergo asymmetric-to-symmetric transitions during signal transduction and catalysis. A thermodynamic framework for signaling that encompasses these various properties is presented and the consequences of weak thermodynamic coupling are discussed. The synthesis of observations from enzymology, structural biology, protein engineering and thermodynamics paves the way for a deeper molecular understanding of histidine kinase signal transduction. PMID:25982528

  4. Theory and modeling of cylindrical thermo-acoustic transduction

    NASA Astrophysics Data System (ADS)

    Tong, Lihong; Lim, C. W.; Zhao, Xiushao; Geng, Daxing

    2016-06-01

    Models both for solid and thinfilm-solid cylindrical thermo-acoustic transductions are proposed and the corresponding acoustic pressure solutions are obtained. The acoustic pressure for an individual carbon nanotube (CNT) as a function of input power is investigated analytically and it is verified by comparing with the published experimental data. Further numerical analysis on the acoustic pressure response and characteristics for varying input frequency and distance are also examined both for solid and thinfilm-solid cylindrical thermo-acoustic transductions. Through detailed theoretical and numerical studies on the acoustic pressure solution for thinfilm-solid cylindrical transduction, it is concluded that a solid with smaller thermal conductivity favors to improve the acoustic performance. In general, the proposed models are applicable to a variety of cylindrical thermo-acoustic devices performing in different gaseous media.

  5. Physical and genetical analysis of bacteriophage T4 generalized transduction.

    PubMed

    Young, K K; Edlin, G

    1983-01-01

    This report describes a comparison of the efficiency of transduction of genes in E. coli by the generalized transducing bacteriophages T4GT7 and P1CM. Both phages are capable of transducing many genetic markers in E. coli although the frequency of transduction for particular genes varies over a wide range. The frequency of transduction for most genes depends on which transducing phage is used as well as on the donor and recipient bacterial strains. Analysis of T4GT7 phage lysates by cesium chloride density gradient centrifugation shows that transducing phage particles contain primarily bacterial DNA and carry little, if any, phage DNA. In this regard transducing phages P1CM and T4GT7 are similar; both phages package either bacterial or phage DNA but not both DNAs into the same particle.

  6. Developmental outcomes among 18-month-old Malawians after a year of complementary feeding with lipid-based nutrient supplements or corn-soy flour

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The major aim of this trial was to compare the development of 18-month-old infants who received complementary feeding for 1 year with either lipid-based nutrient supplements or micronutrient-fortified corn-soy porridge. Our secondary aim was to determine the socio-economic factors associated with de...

  7. Postintervention growth of Malawian children who received 12-mo dietary complementation with a lipid-based nutrient supplement or maize-soy flour

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Therapeutic feeding with micronutrient-fortified lipid-based nutrient supplements (LNSs) has proven useful in the rehabilitation of severely malnourished children. We recently reported that complementary feeding of 6 to 18-mo-old infants with LNS known as FS50, was associated with improved linear gr...

  8. Cationic electrodepositable coating composition comprising lignin

    DOEpatents

    Fenn, David; Bowman, Mark P; Zawacky, Steven R; Van Buskirk, Ellor J; Kamarchik, Peter

    2013-07-30

    A cationic electrodepositable coating composition is disclosed. The present invention in directed to a cationic electrodepositable coating composition comprising a lignin-containing cationic salt resin, that comprises (A) the reaction product of: lignin, an amine, and a carbonyl compound; (B) the reaction product of lignin, epichlorohydrin, and an amine; or (C) combinations thereof.

  9. Studying Chemoattractant Signal Transduction Dynamics in Dictyostelium by BRET.

    PubMed

    Islam, A F M Tariqul; Stepanski, Branden M; Charest, Pascale G

    2016-01-01

    Understanding the dynamics of chemoattractant signaling is key to our understanding of the mechanisms underlying the directed migration of cells, including that of neutrophils to sites of infections and of cancer cells during metastasis. A model frequently used for deciphering chemoattractant signal transduction is the social amoeba Dictyostelium discoideum. However, the methods available to quantitatively measure chemotactic signaling are limited. Here, we describe a protocol to quantitatively study chemoattractant signal transduction in Dictyostelium by monitoring protein-protein interactions and conformational changes using Bioluminescence Resonance Energy Transfer (BRET). PMID:27271894

  10. Mechanism and evolution of cytosolic Hedgehog signal transduction

    PubMed Central

    Wilson, Christopher W.; Chuang, Pao-Tien

    2010-01-01

    Hedgehog (Hh) signaling is required for embryonic patterning and postnatal physiology in invertebrates and vertebrates. With the revelation that the primary cilium is crucial for mammalian Hh signaling, the prevailing view that Hh signal transduction mechanisms are conserved across species has been challenged. However, more recent progress on elucidating the function of core Hh pathway cytosolic regulators in Drosophila, zebrafish and mice has confirmed that the essential logic of Hh transduction is similar between species. Here, we review Hh signaling events at the membrane and in the cytosol, and focus on parallel and divergent functions of cytosolic Hh regulators in Drosophila and mammals. PMID:20530542

  11. Modelling protein functional domains in signal transduction using Maude

    NASA Technical Reports Server (NTRS)

    Sriram, M. G.

    2003-01-01

    Modelling of protein-protein interactions in signal transduction is receiving increased attention in computational biology. This paper describes recent research in the application of Maude, a symbolic language founded on rewriting logic, to the modelling of functional domains within signalling proteins. Protein functional domains (PFDs) are a critical focus of modern signal transduction research. In general, Maude models can simulate biological signalling networks and produce specific testable hypotheses at various levels of abstraction. Developing symbolic models of signalling proteins containing functional domains is important because of the potential to generate analyses of complex signalling networks based on structure-function relationships.

  12. Signal transduction pathways involved in mechanotransduction in bone cells

    SciTech Connect

    Liedert, Astrid . E-mail: astrid.liedert@uni-ulm.de; Kaspar, Daniela; Blakytny, Robert; Claes, Lutz; Ignatius, Anita

    2006-10-13

    Several in vivo and in vitro studies with different loading regimens showed that mechanical stimuli have an influence on proliferation and differentiation of bone cells. Prerequisite for this influence is the transduction of mechanical signals into the cell, a phenomenon that is termed mechanotransduction, which is essential for the maintenance of skeletal homeostasis in adults. Mechanoreceptors, such as the integrins, cadherins, and stretch-activated Ca{sup 2+} channels, together with various signal transduction pathways, are involved in the mechanotransduction process that ultimately regulates gene expression in the nucleus. Mechanotransduction itself is considered to be regulated by hormones, the extracellular matrix of the osteoblastic cells and the mode of the mechanical stimulus.

  13. Cavity optoelectromechanical system combining strong electrical actuation with ultrasensitive transduction

    SciTech Connect

    McRae, Terry G.; Lee, Kwan H.; Harris, Glen I.; Knittel, Joachim; Bowen, Warwick P.

    2010-08-15

    A cavity optoelectromechanical system is reported which combines the ultrasensitive transduction of cavity optomechanical systems with the electrical actuation of nanoelectromechanical systems. Ultrasensitive mechanical transduction is achieved via optomechanical coupling. Electrical gradient forces as large as 0.40 {mu}N are realized, facilitating strong actuation with ultralow dissipation. A scanning probe microscope is implemented, capable of characterizing the mechanical modes. The integration of electrical actuation into optomechanical devices is an enabling step toward the regime of quantum nonlinear dynamics and provides capabilities for quantum control of mechanical motion.

  14. Calorimetric study of cationic photopolymerization

    NASA Astrophysics Data System (ADS)

    Czajlik, I.; Hedvig, P.; Ille, A.; Dobó, J.

    1996-03-01

    The photopolymerization of penta-erythritol tetra-glycidyl ether (initiator Degacure KI-85) was studied by a du Pont 910 type DSC. From our experimental results the following conclusions can be drawn: (1) During the cationic polymerization reaction the lifetime of the initiating centers are long compared to the lifetime of free radicals in case of radical polymerization. (2) The rate of deactivation of the initiating centers increases with increasing temperature.

  15. Lipid-based oral delivery systems for skin deposition of a potential chemopreventive DIM derivative: characterization and evaluation.

    PubMed

    Boakye, Cedar H A; Patel, Ketan; Patel, Apurva R; Faria, Henrique A M; Zucolotto, Valtencir; Safe, Stephen; Singh, Mandip

    2016-10-01

    The objective of this study was to explore the oral route as a viable potential for the skin deposition of a novel diindolylmethane derivative (DIM-D) for chemoprevention activity. Various lipid-based oral delivery systems were optimized and compared for enhancing DIM-D's oral bioavailability and skin deposition. Preformulation studies were performed to evaluate the log P and solubility of DIM-D. Microsomal metabolism, P-glycoprotein efflux, and caco-2 monolayer permeability of DIM-D were determined. Comparative evaluation of the oral absorption and skin deposition of DIM-D-loaded various lipid-based formulations was performed in rats. DIM-D showed pH-dependent solubility and a high log P value. It was not a strong substrate of microsomal degradation and P-glycoprotein. SMEDDs comprised of medium chain triglycerides, monoglycerides, and kolliphor-HS15 (36.70 ± 0.42 nm). SNEDDs comprised of long chain triglycerides, cremophor RH40, labrasol, and TPGS (84.00 ± 14.14 nm). Nanostructured lipid carriers (NLC) consisted of compritol, miglyol, and surfactants (116.50 ± 2.12 nm). The blank formulations all showed >70 % cell viability in caco-2 cells. Differential Scanning Calorimetry confirmed the amorphization of DIM-D within the lipid matrices while Atomic Force Microscopy showed particle size distribution similar to the dynamic light scattering data. DIM-D also showed reduced permeation across caco-2 monolayer that was enhanced (p < 0.05) by SNEDDs in comparison to SMEDDs and NLC. Fabsolute for DIM-D SNEDDs, SMEDDs, and NLC was 0.14, 0.04, and 0.007, respectively. SNEDDs caused 53.90, 11.32, and 15.08-fold more skin deposition of DIM-D than the free drug, SMEDDs, and NLC, respectively, at 2 h following oral administration and shows a viable potential for use in skin cancer chemoprevention. Graphical Abstract ᅟ. PMID:27405772

  16. Lipid-based oral delivery systems for skin deposition of a potential chemopreventive DIM derivative: characterization and evaluation.

    PubMed

    Boakye, Cedar H A; Patel, Ketan; Patel, Apurva R; Faria, Henrique A M; Zucolotto, Valtencir; Safe, Stephen; Singh, Mandip

    2016-10-01

    The objective of this study was to explore the oral route as a viable potential for the skin deposition of a novel diindolylmethane derivative (DIM-D) for chemoprevention activity. Various lipid-based oral delivery systems were optimized and compared for enhancing DIM-D's oral bioavailability and skin deposition. Preformulation studies were performed to evaluate the log P and solubility of DIM-D. Microsomal metabolism, P-glycoprotein efflux, and caco-2 monolayer permeability of DIM-D were determined. Comparative evaluation of the oral absorption and skin deposition of DIM-D-loaded various lipid-based formulations was performed in rats. DIM-D showed pH-dependent solubility and a high log P value. It was not a strong substrate of microsomal degradation and P-glycoprotein. SMEDDs comprised of medium chain triglycerides, monoglycerides, and kolliphor-HS15 (36.70 ± 0.42 nm). SNEDDs comprised of long chain triglycerides, cremophor RH40, labrasol, and TPGS (84.00 ± 14.14 nm). Nanostructured lipid carriers (NLC) consisted of compritol, miglyol, and surfactants (116.50 ± 2.12 nm). The blank formulations all showed >70 % cell viability in caco-2 cells. Differential Scanning Calorimetry confirmed the amorphization of DIM-D within the lipid matrices while Atomic Force Microscopy showed particle size distribution similar to the dynamic light scattering data. DIM-D also showed reduced permeation across caco-2 monolayer that was enhanced (p < 0.05) by SNEDDs in comparison to SMEDDs and NLC. Fabsolute for DIM-D SNEDDs, SMEDDs, and NLC was 0.14, 0.04, and 0.007, respectively. SNEDDs caused 53.90, 11.32, and 15.08-fold more skin deposition of DIM-D than the free drug, SMEDDs, and NLC, respectively, at 2 h following oral administration and shows a viable potential for use in skin cancer chemoprevention. Graphical Abstract ᅟ.

  17. A microstructural study of water effects in lipid-based pharmaceutical formulations for liquid filling of capsules.

    PubMed

    Machado, Alexandra H E; Kokubo, Tohru; Dujovny, Gabriela; Jones, Brian; Scialdone, Claudio; Bravo, Roberto; Kuentz, Martin

    2016-07-30

    Water is known to exhibit pronounced effects on lipid-based formulations (LBFs) and much research has focused on aqueous dispersion and dilution behavior regarding biopharmaceutical performance. From a product quality perspective, it is also critical to study a range of lower water amounts in formulations with respect to capsule filling. The present work addressed the need for a better understanding of LBF microstructure by taking percolation theory into account. The effects of increasing amounts of water on LBFs were analyzed by conductivity, water activity, time-domain nuclear magnetic resonance, and diffusing wave spectroscopy. Results were interpreted using percolation theory and preliminary mechanical tests were conducted on gelatin and hypromellose (HPMC) capsule shells. For both LBF systems, increasing water amounts led to marked changes in the microstructure of the formulations. Percolation laws could be fitted adequately to the data and thresholds were identified for the formation of continuous water channels (ϕwc~0.02-0.06). A new theoretical model was proposed for water activity. The preliminary shell material studies showed that the threshold for generating water channels in the formulation could be correlated to mechanical changes of the capsule shell that were relatively more pronounced in the case of gelatin. This mechanistic study demonstrated the importance of understanding and monitoring of microstructural changes occurring in LBFs with increasing amounts of water, which will help to design quality into the final dosage form. PMID:27132811

  18. Novel Nanostructured Solid Materials for Modulating Oral Drug Delivery from Solid-State Lipid-Based Drug Delivery Systems.

    PubMed

    Dening, Tahnee J; Rao, Shasha; Thomas, Nicky; Prestidge, Clive A

    2016-01-01

    Lipid-based drug delivery systems (LBDDS) have gained significant attention in recent times, owing to their ability to overcome the challenges limiting the oral delivery of poorly water-soluble drugs. Despite the successful commercialization of several LBDDS products over the years, a large discrepancy exists between the number of poorly water-soluble drugs displaying suboptimal in vivo performances and the application of LBDDS to mitigate their various delivery challenges. Conventional LBDDS, including lipid solutions and suspensions, emulsions, and self-emulsifying formulations, suffer from various drawbacks limiting their widespread use and commercialization. Accordingly, solid-state LBDDS, fabricated by adsorbing LBDDS onto a chemically inert solid carrier material, have attracted substantial interest as a viable means of stabilizing LBDDS whilst eliminating some of the various limitations. This review describes the impact of solid carrier choice on LBDDS performance and highlights the importance of appropriate solid carrier material selection when designing hybrid solid-state LBDDS. Specifically, emphasis is placed on discussing the ability of the specific solid carrier to modulate drug release, control lipase action and lipid digestion, and enhance biopharmaceutical performance above the original liquid-state LBDDS. To encourage the interested reader to consider their solid carrier choice on a higher level, various novel materials with the potential for future use as solid carriers for LBDDS are described. This review is highly significant in guiding future research directions in the solid-state LBDDS field and fostering the translation of these delivery systems to the pharmaceutical marketplace. PMID:26354801

  19. A comparative study of curcumin-loaded lipid-based nanocarriers in the treatment of inflammatory bowel disease.

    PubMed

    Beloqui, Ana; Memvanga, Patrick B; Coco, Régis; Reimondez-Troitiño, Sonia; Alhouayek, Mireille; Muccioli, Giulio G; Alonso, María José; Csaba, Noemi; de la Fuente, María; Préat, Véronique

    2016-07-01

    Selective drug delivery to inflamed tissues is of widespread interest for the treatment of inflammatory bowel disease (IBD). Because a lack of physiological lipids has been described in patients suffering IBD, and some lipids present immunomodulatory properties, we hypothesize that the combination of lipids and anti-inflammatory drugs together within a nanocarrier may be a valuable strategy for overcoming IBD. In the present study, we investigated and compared the in vitro and in vivo efficacy of three lipid-based nanocarriers containing curcumin (CC) as an anti-inflammatory drug for treating IBD in a murine DSS-induced colitis model. These nanocarriers included self-nanoemulsifying drug delivery systems (SNEDDS), nanostructured lipid carriers (NLC) and lipid core-shell protamine nanocapsules (NC). In vitro, a 30-fold higher CC permeability across Caco-2 cell monolayers was obtained using NC compared to SNEDDS (NC>SNEDDS>NLC and CC suspension). The CC SNEDDS and CC NLC but not the CC NC or CC suspension significantly reduced TNF-α secretion by LPS-activated macrophages (J774 cells). In vivo, only CC NLC were able to significantly decrease neutrophil infiltration and TNF-α secretion and, thus, colonic inflammation. Our results show that a higher CC permeability does not correlate with a higher efficacy in IBD treatment, which suggests that lipidic nanocarriers exhibiting increased CC retention at the intestinal site, rather than increased CC permeability are efficient treatments of IBD. PMID:27022873

  20. Preventative lipid-based nutrient supplements (LNS) and young child feeding practices: findings from qualitative research in Haiti.

    PubMed

    Lesorogol, Carolyn; Jean-Louis, Sherlie; Green, Jamie; Iannotti, Lora

    2015-12-01

    To prevent undernutrition in an urban slum in Haiti, a lipid-based nutrient supplement (LNS) was introduced through a randomised control trial. Food supplementation for young child nutrition has a long history in Haiti, but there is little empirical information regarding the effects of supplementation on young child feeding practices. One of the concerns raised by supplementation is that it may disrupt other positive feeding practices such as breastfeeding and use of other complementary foods, with negative consequences for child nutrition. We conducted 29 in-depth interviews with mother-baby pairs from the three comparison groups: control, 3-month LNS supplementation and 6-month LNS supplementation. Findings from those in the LNS groups indicated high acceptance and satisfaction with LNS and perceptions that it positively affects child health and development. LNS was integrated into and enhanced ongoing complementary feeding practices. The effects of LNS use on duration and perceived quantity of breastfeeding were variable, but generally, breastfeeding was maintained during and after the intervention. Interviews generated insights into beliefs regarding infant and young child feeding practices such as introduction and use of complementary foods, and breastfeeding duration, exclusivity and cessation. Implications for the use of LNS in public health nutrition programmes are discussed.

  1. Novel Nanostructured Solid Materials for Modulating Oral Drug Delivery from Solid-State Lipid-Based Drug Delivery Systems.

    PubMed

    Dening, Tahnee J; Rao, Shasha; Thomas, Nicky; Prestidge, Clive A

    2016-01-01

    Lipid-based drug delivery systems (LBDDS) have gained significant attention in recent times, owing to their ability to overcome the challenges limiting the oral delivery of poorly water-soluble drugs. Despite the successful commercialization of several LBDDS products over the years, a large discrepancy exists between the number of poorly water-soluble drugs displaying suboptimal in vivo performances and the application of LBDDS to mitigate their various delivery challenges. Conventional LBDDS, including lipid solutions and suspensions, emulsions, and self-emulsifying formulations, suffer from various drawbacks limiting their widespread use and commercialization. Accordingly, solid-state LBDDS, fabricated by adsorbing LBDDS onto a chemically inert solid carrier material, have attracted substantial interest as a viable means of stabilizing LBDDS whilst eliminating some of the various limitations. This review describes the impact of solid carrier choice on LBDDS performance and highlights the importance of appropriate solid carrier material selection when designing hybrid solid-state LBDDS. Specifically, emphasis is placed on discussing the ability of the specific solid carrier to modulate drug release, control lipase action and lipid digestion, and enhance biopharmaceutical performance above the original liquid-state LBDDS. To encourage the interested reader to consider their solid carrier choice on a higher level, various novel materials with the potential for future use as solid carriers for LBDDS are described. This review is highly significant in guiding future research directions in the solid-state LBDDS field and fostering the translation of these delivery systems to the pharmaceutical marketplace.

  2. Syngeneic AAV pseudo-vectors potentiates full vector transduction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An excessive amount of empty capsids are generated during regular AAV vector production process. These pseudo-vectors often remain in final vectors used for animal studies or clinical trials. The potential effects of these pseudo-vectors on AAV transduction have been a major concern. In the current ...

  3. Mitogen-activated protein kinase and abscisic acid signal transduction.

    PubMed

    Heimovaara-Dijkstra, S; Testerink, C; Wang, M

    2000-01-01

    The phytohormone abscisic acid (ABA) is a classical plant hormone, responsible for regulation of abscission, diverse aspects of plant and seed development, stress responses and germination. It was found that ABA signal transduction in plants can involve the activity of type 2C-phosphatases (PP2C), calcium, potassium, pH and a transient activation of MAP kinase. The ABA signal transduction cascades have been shown to be tissue-specific, the transient activation of MAP kinase has until now only been found in barley aleurone cells. However, type 2C phosphatases are involved in the induction of most ABA responses, as shown by the PP2C-deficient abi-mutants. These phosphatases show high homology with phosphatases that regulate MAP kinase activity in yeast. In addition, the role of farnesyl transferase as a negative regulator of ABA responses also indicates towards involvement of MAP kinase in ABA signal transduction. Farnesyl transferase is known to regulate Ras proteins, Ras proteins in turn are known to regulate MAP kinase activation. Interestingly, Ras-like proteins were detected in barley aleurone cells. Further establishment of the involvement of MAP kinase in ABA signal transduction and its role therein, still awaits more study.

  4. Protein phosphorylation and its role in archaeal signal transduction.

    PubMed

    Esser, Dominik; Hoffmann, Lena; Pham, Trong Khoa; Bräsen, Christopher; Qiu, Wen; Wright, Phillip C; Albers, Sonja-Verena; Siebers, Bettina

    2016-09-01

    Reversible protein phosphorylation is the main mechanism of signal transduction that enables cells to rapidly respond to environmental changes by controlling the functional properties of proteins in response to external stimuli. However, whereas signal transduction is well studied in Eukaryotes and Bacteria, the knowledge in Archaea is still rather scarce. Archaea are special with regard to protein phosphorylation, due to the fact that the two best studied phyla, the Euryarchaeota and Crenarchaeaota, seem to exhibit fundamental differences in regulatory systems. Euryarchaeota (e.g. halophiles, methanogens, thermophiles), like Bacteria and Eukaryotes, rely on bacterial-type two-component signal transduction systems (phosphorylation on His and Asp), as well as on the protein phosphorylation on Ser, Thr and Tyr by Hanks-type protein kinases. Instead, Crenarchaeota (e.g. acidophiles and (hyper)thermophiles) only depend on Hanks-type protein phosphorylation. In this review, the current knowledge of reversible protein phosphorylation in Archaea is presented. It combines results from identified phosphoproteins, biochemical characterization of protein kinases and protein phosphatases as well as target enzymes and first insights into archaeal signal transduction by biochemical, genetic and polyomic studies.

  5. Protein phosphorylation and its role in archaeal signal transduction.

    PubMed

    Esser, Dominik; Hoffmann, Lena; Pham, Trong Khoa; Bräsen, Christopher; Qiu, Wen; Wright, Phillip C; Albers, Sonja-Verena; Siebers, Bettina

    2016-09-01

    Reversible protein phosphorylation is the main mechanism of signal transduction that enables cells to rapidly respond to environmental changes by controlling the functional properties of proteins in response to external stimuli. However, whereas signal transduction is well studied in Eukaryotes and Bacteria, the knowledge in Archaea is still rather scarce. Archaea are special with regard to protein phosphorylation, due to the fact that the two best studied phyla, the Euryarchaeota and Crenarchaeaota, seem to exhibit fundamental differences in regulatory systems. Euryarchaeota (e.g. halophiles, methanogens, thermophiles), like Bacteria and Eukaryotes, rely on bacterial-type two-component signal transduction systems (phosphorylation on His and Asp), as well as on the protein phosphorylation on Ser, Thr and Tyr by Hanks-type protein kinases. Instead, Crenarchaeota (e.g. acidophiles and (hyper)thermophiles) only depend on Hanks-type protein phosphorylation. In this review, the current knowledge of reversible protein phosphorylation in Archaea is presented. It combines results from identified phosphoproteins, biochemical characterization of protein kinases and protein phosphatases as well as target enzymes and first insights into archaeal signal transduction by biochemical, genetic and polyomic studies. PMID:27476079

  6. Protein phosphorylation and its role in archaeal signal transduction

    PubMed Central

    Esser, Dominik; Hoffmann, Lena; Pham, Trong Khoa; Bräsen, Christopher; Qiu, Wen; Wright, Phillip C.; Albers, Sonja-Verena; Siebers, Bettina

    2016-01-01

    Reversible protein phosphorylation is the main mechanism of signal transduction that enables cells to rapidly respond to environmental changes by controlling the functional properties of proteins in response to external stimuli. However, whereas signal transduction is well studied in Eukaryotes and Bacteria, the knowledge in Archaea is still rather scarce. Archaea are special with regard to protein phosphorylation, due to the fact that the two best studied phyla, the Euryarchaeota and Crenarchaeaota, seem to exhibit fundamental differences in regulatory systems. Euryarchaeota (e.g. halophiles, methanogens, thermophiles), like Bacteria and Eukaryotes, rely on bacterial-type two-component signal transduction systems (phosphorylation on His and Asp), as well as on the protein phosphorylation on Ser, Thr and Tyr by Hanks-type protein kinases. Instead, Crenarchaeota (e.g. acidophiles and (hyper)thermophiles) only depend on Hanks-type protein phosphorylation. In this review, the current knowledge of reversible protein phosphorylation in Archaea is presented. It combines results from identified phosphoproteins, biochemical characterization of protein kinases and protein phosphatases as well as target enzymes and first insights into archaeal signal transduction by biochemical, genetic and polyomic studies. PMID:27476079

  7. MOLECULAR MECHANISMS OF RECEPTOR KINASE ACTION IN BRASSINOSTEROID SIGNAL TRANSDUCTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Brassinosteroids (BRs) regulate multiple aspects of plant growth and development and require an active BRASSINOSTEROID INSENSITIVE 1 (BRI1) and BRI1-ASSOCIATED RECEPTOR KINASE 1 (BAK1) for hormone perception and signal transduction. To examine early events in BR signaling, we used co-immunoprecipita...

  8. Rapid methods for generalized transduction of Salmonella typhimurium mutants.

    PubMed

    Rosenfeld, S A; Brenchley, J

    1979-04-01

    A procedure has been developed that allows the propagation of generalized transducing phage directly on cells growing on solid media. After the donor cells are killed with chloroform, the phage can be transferred directly to recipient cells and transductants can be selected.

  9. Efficacious redox-responsive gene delivery in serum by ferrocenylated monomeric and dimeric cationic cholesterols.

    PubMed

    Vulugundam, Gururaja; Kumar, Krishan; Kondaiah, Paturu; Bhattacharya, Santanu

    2015-04-14

    Herein, we present the design and synthesis of new redox-active monomeric and dimeric (gemini) cationic lipids based on ferrocenylated cholesterol derivatives for gene delivery. The cationic cholesterols are shown to be transfection efficient after being formulated with the neutral helper lipid DOPE in the presence of serum (FBS). The redox activity of the resulting co-liposomes and their lipoplexes could be regulated using the alkanyl ferrocene moiety attached to the ammonium head groups of the cationic cholesterols. Atomic force microscopy (AFM), dynamic light scattering (DLS) and zeta potential measurements were performed to characterize the co-liposomal aggregates and their complexes with pDNA. The transfection efficiency of lipoplexes could be tuned by changing the oxidation state of the ferrocene moiety. The gene transfection capability was assayed in terms of green fluorescence protein (GFP) expression using pEGFP-C3 plasmid DNA in three cell lines of different origins, namely Caco-2, HEK293T and HeLa, in the presence of serum. The vesicles possessing ferrocene in the reduced state induced an efficient transfection, even better than a commercial reagent Lipofectamine 2000 (Lipo 2000) as evidenced by flow cytometry and fluorescence microscopy. All the co-liposomes containing the oxidized ferrocene displayed diminished levels of gene expression. Gene transfection events from the oxidized co-liposomes were further potentiated by introducing ascorbic acid (AA) as a reducing agent during lipoplex incubation with cells, leading to the resumption of transfection activity. Assessment of transfection capability of both reduced and oxidized co-liposomes was also undertaken following cellular internalization of labelled pDNA using confocal microscopy and flow cytometry. Overall, we demonstrate here controlled gene transfection activities using redox-driven, transfection efficient cationic monomeric and dimeric cholesterol lipids. Such systems could be used in gene

  10. Cation disorder in shocked orthopyroxene.

    NASA Technical Reports Server (NTRS)

    Dundon, R. W.; Hafner, S. S.

    1971-01-01

    The study of cation distributions over nonequivalent lattice sites in minerals may reveal information on the history of temperature and pressure in rocks. Chemically homogeneous orthopyroxene specimens were shocked under well-controlled conditions in the laboratory in order to provide a basis for the interpretation of more complex natural materials. As a result of the investigation it is concluded that the distribution of magnesium and iron over the M1 and M2 positions in Bamle enstatite shocked at 1 megabar is highly disordered. It corresponds to an equilibrium distribution of at least 1000 C.

  11. Transduction heats in retinal rods: tests of the role of cGMP by pyroelectric calorimetry.

    PubMed Central

    Hagins, W A; Ross, P D; Tate, R L; Yoshikami, S

    1989-01-01

    The sensory dark current of vertebrate retinal rods is believed to be controlled by light activation of a chain of coupled biochemical cycles that finally regulate the cationic conductance of the plasma membrane by hydrolytically reducing the level of cGMP in rod outer segment cytoplasm. The scheme has been tested by measuring heat production by live frog retinas when stimulated with sequences of light flashes of progressively increasing energy. Using pyroelectric poly(vinylidene 1,1-difluoride) detectors that simultaneously measure transretinal voltage and retinal temperature change, four heat effects assignable to known biochemical cycles in rods have been found. As the dark current shuts down after a flash causing 180-1800 rhodopsin photoisomerizations per rod, a heat burst, q1, raises the retinal temperature 1-2 microK. q1 is closely regulated in size and slightly precedes dark current shutdown. Isobutylmethylxanthine slows and enlarges q1, delaying the dark-current response. Increasing cytoplasmic Ca2+ stops the dark current without affecting q1. Although rod heat production is consistent with splitting of 1-3 microM of free cytoplasmic cGMP during transduction, the kinetics of the two processes do not match the predictions of current cGMP control models. PMID:2537492

  12. In vivo biodistribution, biocompatibility, and efficacy of sorafenib-loaded lipid-based nanosuspensions evaluated experimentally in cancer

    PubMed Central

    Yang, Shaomei; Zhang, Bo; Gong, Xiaowei; Wang, Tianqi; Liu, Yongjun; Zhang, Na

    2016-01-01

    Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. In this study, sorafenib-loaded lipid-based nanosuspensions (sorafenib-LNS) were first developed as an intravenous injectable formulation to increase the efficacy of sorafenib against HCC. LNS were used as nanocarriers for sorafenib owing to their desired features in increasing the solubility and dissolution velocity, improving the bioavailability of sorafenib. Sorafenib-LNS were prepared by nanoprecipitation and consisted of spherical particles with a uniform size distribution (164.5 nm, polydispersity index =0.202) and negative zeta potential (−11.0 mV). The drug loading (DL) was 10.55%±0.16%. Sorafenib-LNS showed higher in vitro cytotoxicity than sorafenib against HepG2 cells (P<0.05) and Bel-7402 cells (P<0.05). The in vivo biodistribution, biocompatibility, and antitumor efficacy of sorafenib-LNS were evaluated in H22-bearing liver cancer xenograft murine model. The results showed that sorafenib-LNS (9 mg/kg) exhibited significantly higher antitumor efficacy by reducing the tumor volume compared with the sorafenib oral group (18 mg/kg, P<0.05) and sorafenib injection group (9 mg/kg, P<0.05). Furthermore, the results of the in vivo biodistribution experiments demonstrated that sorafenib-LNS injected into H22 tumor-bearing mice exhibited increased accumulation in the tumor tissue, which was confirmed by in vivo imaging. In the current experimental conditions, sorafenib-LNS did not show significant toxicity both in vitro and in vivo. These results suggest that sorafenib-LNS are a promising nanomedicine for treating HCC. PMID:27307733

  13. In vivo biodistribution, biocompatibility, and efficacy of sorafenib-loaded lipid-based nanosuspensions evaluated experimentally in cancer.

    PubMed

    Yang, Shaomei; Zhang, Bo; Gong, Xiaowei; Wang, Tianqi; Liu, Yongjun; Zhang, Na

    2016-01-01

    Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. In this study, sorafenib-loaded lipid-based nanosuspensions (sorafenib-LNS) were first developed as an intravenous injectable formulation to increase the efficacy of sorafenib against HCC. LNS were used as nanocarriers for sorafenib owing to their desired features in increasing the solubility and dissolution velocity, improving the bioavailability of sorafenib. Sorafenib-LNS were prepared by nanoprecipitation and consisted of spherical particles with a uniform size distribution (164.5 nm, polydispersity index =0.202) and negative zeta potential (-11.0 mV). The drug loading (DL) was 10.55%±0.16%. Sorafenib-LNS showed higher in vitro cytotoxicity than sorafenib against HepG2 cells (P<0.05) and Bel-7402 cells (P<0.05). The in vivo biodistribution, biocompatibility, and antitumor efficacy of sorafenib-LNS were evaluated in H22-bearing liver cancer xenograft murine model. The results showed that sorafenib-LNS (9 mg/kg) exhibited significantly higher antitumor efficacy by reducing the tumor volume compared with the sorafenib oral group (18 mg/kg, P<0.05) and sorafenib injection group (9 mg/kg, P<0.05). Furthermore, the results of the in vivo biodistribution experiments demonstrated that sorafenib-LNS injected into H22 tumor-bearing mice exhibited increased accumulation in the tumor tissue, which was confirmed by in vivo imaging. In the current experimental conditions, sorafenib-LNS did not show significant toxicity both in vitro and in vivo. These results suggest that sorafenib-LNS are a promising nanomedicine for treating HCC.

  14. Recent Trends in Nanotechnology Toward CNS Diseases: Lipid-Based Nanoparticles and Exosomes for Targeted Therapeutic Delivery.

    PubMed

    Cardoso, A M; Guedes, J R; Cardoso, A L; Morais, C; Cunha, P; Viegas, A T; Costa, R; Jurado, A; Pedroso de Lima, M C

    2016-01-01

    Central nervous system (CNS) diseases constitute a set of challenging pathological conditions concerning diagnosis and therapeutics. For most of these disorders, there is a lack of early diagnosis, biomarkers to allow proper follow-up of disease progression and effective therapeutic strategies to allow a persistent cure. The poor prognosis of most CNS diseases is, therefore, a global concern, especially regarding chronic age-related neurodegenerative disorders, which are already considered problems of public health due to the increasing average of life expectancy. The difficulties associated with the treatment of CNS diseases are owed, at least in part, to very specific characteristics of the brain and spinal cord, when compared to peripheral organs. In this regard, the CNS is physically and chemically protected by the blood-brain barrier (BBB), which, while maintaining essential brain homeostasis, significantly restricts the delivery of most therapeutic agents to the brain parenchyma. On the other hand, regenerative properties of the tissue are lacking, meaning that a CNS insult resulting in neuronal death is a permanent phenomenon. Approaches for transposing the BBB aiming to treat CNS diseases, relying on specific properties of nanosystems, have been reported for therapeutic delivery to CNS without interfering with the normal function of the brain. In this chapter, we address the latest advances concerning the principles of such approaches, employing lipid-based nanoparticles and cell-produced exosomes as drug and nucleic acid delivery systems, and summarize recent example of applications in the context of neurological diseases. Major achievements obtained in preclinical studies and the trends identified by these studies are emphasized to provide new prospects for further developments in this area, thus enabling us to move from the research realm to the clinical arena. PMID:27678173

  15. Design of lipid-based formulations for oral administration of poorly water-soluble drug fenofibrate: effects of digestion.

    PubMed

    Mohsin, Kazi

    2012-06-01

    Lipid-based drug carriers are likely to have influence on bioavailability through enhanced solubilization of the drug in the gastrointestinal tract. The study was designed to investigate the lipid formulation digestibility in the simulated gastro intestinal media. Fenofibrate was formulated in representative Type II, IIIA, IIIB and IV self-emulsifying/microemulsifying lipid delivery systems (SEDDS and SMEDDS designed for oral administration) using various medium-chain glyceride components, non-ionic surfactants and cosolvents as excipients. Soybean oil was used only as an example of long-chain triglycerides to compare the effects of formulation with their counterparts. The formulations were subjected to in vitro digestion specifically to predict the fate of the drug in the gastro intestinal tract after exposure of the formulation to pancreatic enzymes and bile. In vitro digestion experiments were carried out using a pH-stat maintained at pH 7.5 for 30 min using intestinal fluids simulating the fed and fasted states. The digestion rate was faster and almost completed in Type II and IIIA systems. Most of the surfactants used in the studies are digestible. However, the high concentration of surfactant and/or cosolvent used in Type IIIB or IV systems lowered the rate of digestion. The digestion of medium-chain triglycerides was faster than long-chain triglycerides, but kept comparatively less drug in the post digestion products. Medium-chain mixed glycerides are good solvents for fenofibrate as rapidly digested but to improve fenofibrate concentration in post digestion products the use of long-chain mixed glycerides are suggested for further investigations.

  16. Acceptability of zinc-fortified, lipid-based nutrient supplements (LNS) prepared for young children in Burkina Faso.

    PubMed

    Hess, Sonja Y; Bado, Lucien; Aaron, Grant J; Ouédraogo, Jean-Bosco; Zeilani, Mamane; Brown, Kenneth H

    2011-10-01

    Micronutrient deficiencies are a public health concern among young children in low-income countries, and novel strategies are needed to improve the nutritional status of children at risk. One promising approach is the use of lipid-based nutrient supplements (LNS), which can be added to complementary food at the time of consumption. The optimal amount of zinc to include in LNS is uncertain, and concerns have been expressed about possible adverse effects of zinc on sensory characteristics of LNS. We conducted a series of acceptability studies of LNS containing either 0 or 10 mg of zinc per daily 20 g LNS dose among Burkinabe children 9-15 months old and their mothers. These acceptability studies included observations of children's consumption, maternal and child sensory reaction to the products using a 5-unit hedonic scale, a triangle test for detection of differences and a review of maternal reports of their child-feeding experiences during a 2-week home-feeding trial. The LNS products were well appreciated by the mothers and children during the sensory trials and the 2-week home-feeding trial. The addition of 10 mg zinc to LNS did not affect the consumed proportion of the offered porridge-LNS-mixture (P = 0.43). Results of the triangle test with mothers confirmed that there was no detectable difference between products containing 0 or 10 mg zinc per 20 g LNS dose. Most importantly, interviews and focus groups following the 2-week home-feeding trial indicated good acceptability of the products by mothers and their children.

  17. Prenatal lipid-based nutrient supplements increase cord leptin concentration in pregnant women from rural Burkina Faso.

    PubMed

    Huybregts, Lieven; Roberfroid, Dominique; Lanou, Hermann; Meda, Nicolas; Taes, Youri; Valea, Innocent; D'Alessandro, Umberto; Kolsteren, Patrick; Van Camp, John

    2013-05-01

    In developing countries, prenatal lipid-based nutrient supplements (LNSs) were shown to increase birth size; however, the mechanism of this effect remains unknown. Cord blood hormone concentrations are strongly associated with birth size. Therefore, we hypothesize that LNSs increase birth size through a change in the endocrine regulation of fetal development. We compared the effect of daily prenatal LNSs with multiple micronutrient tablets on cord blood hormone concentrations using a randomized, controlled design including 197 pregnant women from rural Burkina Faso. Insulin-like growth factors (IGF) I and II, their binding proteins IGFBP-1 and IGFBP-3, leptin, cortisol, and insulin were quantified in cord sera using immunoassays. LNS was associated with higher cord blood leptin mainly in primigravidae (+57%; P = 0.02) and women from the highest tertile of BMI at study inclusion (+41%; P = 0.02). We did not find any significant LNS effects on other measured cord hormones. The observed increase in cord leptin was associated with a significantly higher birth weight. Cord sera from small-for-gestational age newborns had lower median IGF-I (-9 μg/L; P = 0.003), IGF-II (-79 μg/L; P = 0.003), IGFBP-3 (-0.7 μg/L; P = 0.007), and leptin (-1.0 μg/L; P = 0.016) concentrations but higher median cortisol (+18 μg/L; P = 0.037) concentrations compared with normally grown newborns. Prenatal LNS resulted in increased cord leptin concentrations in primigravidae and mothers with higher BMI at study inclusion. The elevated leptin concentrations could point toward a higher neonatal fat mass.

  18. Silica encapsulated lipid-based drug delivery systems for reducing the fed/fasted variations of ziprasidone in vitro.

    PubMed

    Dening, Tahnee J; Rao, Shasha; Thomas, Nicky; Prestidge, Clive A

    2016-04-01

    Ziprasidone is a poorly water-soluble antipsychotic drug that demonstrates low fasted state oral bioavailability and a clinically significant two-fold increase in absorption when dosed postprandially. Owing to significant compliance challenges faced by schizophrenic patients, a novel oral formulation of ziprasidone that demonstrates improved fasted state absorption and a reduced food effect is of major interest, and is therefore the aim of this research. Three lipid-based drug delivery systems (LBDDS) were developed and investigated: (a) a self-nanoemulsifying drug delivery system (SNEDDS), (b) a solid SNEDDS formulation, and (c) silica-lipid hybrid (SLH) microparticles. SNEDDS was developed using Capmul MCM® and Tween 80®, and solid SNEDDS was fabricated by spray-drying SNEDDS with Aerosil 380® silica nanoparticles as the solid carrier. SLH microparticles were prepared in a similar manner to solid SNEDDS using a precursor lipid emulsion composed of Capmul MCM® and soybean lecithin. The performance of the developed formulations was evaluated under simulated digesting conditions using an in vitro lipolysis model, and pure (unformulated) ziprasidone was used as a control. While pure ziprasidone exhibited the lowest rate and extent of drug solubilization under fasting conditions and a significant 2.4-fold increase in drug solubilization under fed conditions, all three LBDDS significantly enhanced the extent of drug solubilization under fasting conditions between 18- and 43-folds in comparison to pure drug. No significant difference in drug solubilization for the fed and fasted states was observed for the three LBDDS systems. To highlight the potential of LBDDS, mechanism(s) of action and various performance characteristics are discussed. Importantly, LBDDS are identified as an appropriate formulation strategy to explore further for the improved oral delivery of ziprasidone.

  19. Developing a synthetic signal transduction system in plants.

    PubMed

    Morey, Kevin J; Antunes, Mauricio S; Albrecht, Kirk D; Bowen, Tessa A; Troupe, Jared F; Havens, Keira L; Medford, June I

    2011-01-01

    One area of focus in the emerging field of plant synthetic biology is the manipulation of systems involved in sensing and response to environmental signals. Sensing and responding to signals, including ligands, typically involves biological signal transduction. Plants use a wide variety of signaling systems to sense and respond to their environment. One of these systems, a histidine kinase (HK) based signaling system, lends itself to manipulation using the tools of synthetic biology. Both plants and bacteria use HKs to relay signals, which in bacteria can involve as few as two proteins (two-component systems or TCS). HK proteins are evolutionarily conserved between plants and bacteria and plant HK components have been shown to be functional in bacteria. We found that this conservation also applies to bacterial HK components which can function in plants. This conservation of function led us to hypothesize that synthetic HK signaling components can be designed and rapidly tested in bacteria. These novel HK signaling components form the foundation for a synthetic signaling system in plants, but typically require modifications such as codon optimization and proper targeting to allow optimal function. We describe the process and methodology of producing a synthetic signal transduction system in plants. We discovered that the bacterial response regulator (RR) PhoB shows HK-dependent nuclear translocation in planta. Using this discovery, we engineered a partial synthetic pathway in which a synthetic promoter (PlantPho) is activated using a plant-adapted PhoB (PhoB-VP64) and the endogenous HK-based cytokinin signaling pathway. Building on this work, we adapted an input or sensing system based on bacterial chemotactic binding proteins and HKs, resulting in a complete eukaryotic signal transduction system. Input to our eukaryotic signal transduction system is provided by a periplasmic binding protein (PBP), ribose-binding protein (RBP). RBP interacts with the membrane

  20. Metal cation controls myosin and actomyosin kinetics

    PubMed Central

    Tkachev, Yaroslav V; Ge, Jinghua; Negrashov, Igor V; Nesmelov, Yuri E

    2013-01-01

    We have perturbed myosin nucleotide binding site with magnesium-, manganese-, or calcium-nucleotide complexes, using metal cation as a probe to examine the pathways of myosin ATPase in the presence of actin. We have used transient time-resolved FRET, myosin intrinsic fluorescence, fluorescence of pyrene labeled actin, combined with the steady state myosin ATPase activity measurements of previously characterized D.discoideum myosin construct A639C:K498C. We found that actin activation of myosin ATPase does not depend on metal cation, regardless of the cation-specific kinetics of nucleotide binding and dissociation. The rate limiting step of myosin ATPase depends on the metal cation. The rate of the recovery stroke and the reverse recovery stroke is directly proportional to the ionic radius of the cation. The rate of nucleotide release from myosin and actomyosin, and ATP binding to actomyosin depends on the cation coordination number. PMID:24115140

  1. Electronic spectra of astrophysically interesting cations

    SciTech Connect

    Maier, John P. Rice, Corey A. Mazzotti, Fabio J. Johnson, Anatoly

    2015-01-22

    The electronic spectra of polyacetylene cations were recorded at 20K in the laboratory in an ion trap instrument. These can then be compared with diffuse interstellar band (DIB) absorptions. Examination of recently published data shows that the attribution of a weak DIB at ∼506.9 nm to diacetylene cation is not justified. Study of the higher excited electronic states of polyacetylene cations shows that their widths can still be sufficiently narrow for consideration as DIB carriers.

  2. ADSORPTION METHOD FOR SEPARATING METAL CATIONS

    DOEpatents

    Khym, J.X.

    1959-03-10

    The chromatographic separation of fission product cations is discussed. By use of this method a mixture of metal cations containing Zr, Cb, Ce, Y, Ba, and Sr may be separated from one another. Mentioned as preferred exchange adsorbents are resins containing free sulfonic acid groups. Various eluants, such as tartaric acid, HCl, and citric acid, used at various acidities, are employed to effect the selective elution and separation of the various fission product cations.

  3. Developmental outcomes among 18-month-old Malawians after a year of complementary feeding with lipid-based nutrient supplements or corn-soy flour.

    PubMed

    Phuka, John C; Gladstone, Melissa; Maleta, Kenneth; Thakwalakwa, Chrissie; Cheung, Yin Bun; Briend, André; Manary, Mark J; Ashorn, Per

    2012-04-01

    The major aim of this trial was to compare the development of 18-month-old infants who received complementary feeding for 1 year either with lipid-based nutrient supplements or micronutrient fortified corn-soy porridge. Our secondary aim was to determine the socio-economic factors associated with developmental outcomes in the same population. A total of 163 six-month-old rural Malawian children were enrolled in a randomized controlled trial where the control population received daily supplementation with 71 g corn-soy flour [Likuni Phala (LP)] (282 kcal) and individuals in the intervention groups received daily either 50 g of lipid-based nutrient supplement (FS50) (264 kcal) or 25 g of lipid-based nutrient supplement (FS25) (130 kcal). The main outcome measures were Griffiths' developmental scores at 0-2 years. Independent comparison of study groups was carried out using analysis of variance (ANOVA) statistics where mean raw scores, quotients, or mental ages were compared. Association of developmental outcome with predictor variables were examined using multiple regression. At 18 months of chronological age, the mean ± standard deviation (SD) mental ages in the LP, FS50, and FS25 groups were 17.9 ± 1.3, 17.9 ± 1.3, and 17.9 ± 1.2 (P > 0.99), respectively. Likewise, the mean raw developmental scores and mean developmental quotients did not differ significantly. Length-for-age z-score gain during the intervention period, and maternal education were associated with developmental outcome at 18 months (P = 0.03 and P = 0.04; respectively). In conclusion, rural Malawian infants receiving 12-month daily supplementation of their diet either with the tested lipid-based nutrient supplements or fortified corn-soy flour have comparable development outcomes by 18 months of age. PMID:21342456

  4. High-sensitivity linear piezoresistive transduction for nanomechanical beam resonators.

    PubMed

    Sansa, Marc; Fernández-Regúlez, Marta; Llobet, Jordi; San Paulo, Álvaro; Pérez-Murano, Francesc

    2014-01-01

    Highly sensitive conversion of motion into readable electrical signals is a crucial and challenging issue for nanomechanical resonators. Efficient transduction is particularly difficult to realize in devices of low dimensionality, such as beam resonators based on carbon nanotubes or silicon nanowires, where mechanical vibrations combine very high frequencies with miniscule amplitudes. Here we describe an enhanced piezoresistive transduction mechanism based on the asymmetry of the beam shape at rest. We show that this mechanism enables highly sensitive linear detection of the vibration of low-resistivity silicon beams without the need of exceptionally large piezoresistive coefficients. The general application of this effect is demonstrated by detecting multiple-order modes of silicon nanowire resonators made by either top-down or bottom-up fabrication methods. These results reveal a promising approach for practical applications of the simplest mechanical resonators, facilitating its manufacturability by very large-scale integration technologies. PMID:25000256

  5. Maxwell's demon in biochemical signal transduction with feedback loop

    NASA Astrophysics Data System (ADS)

    Ito, Sosuke; Sagawa, Takahiro

    2015-06-01

    Signal transduction in living cells is vital to maintain life itself, where information transfer in noisy environment plays a significant role. In a rather different context, the recent intensive research on `Maxwell's demon'--a feedback controller that utilizes information of individual molecules--have led to a unified theory of information and thermodynamics. Here we combine these two streams of research, and show that the second law of thermodynamics with information reveals the fundamental limit of the robustness of signal transduction against environmental fluctuations. Especially, we find that the degree of robustness is quantitatively characterized by an informational quantity called transfer entropy. Our information-thermodynamic approach is applicable to biological communication inside cells, in which there is no explicit channel coding in contrast to artificial communication. Our result could open up a novel biophysical approach to understand information processing in living systems on the basis of the fundamental information-thermodynamics link.

  6. High-sensitivity linear piezoresistive transduction for nanomechanical beam resonators.

    PubMed

    Sansa, Marc; Fernández-Regúlez, Marta; Llobet, Jordi; San Paulo, Álvaro; Pérez-Murano, Francesc

    2014-01-01

    Highly sensitive conversion of motion into readable electrical signals is a crucial and challenging issue for nanomechanical resonators. Efficient transduction is particularly difficult to realize in devices of low dimensionality, such as beam resonators based on carbon nanotubes or silicon nanowires, where mechanical vibrations combine very high frequencies with miniscule amplitudes. Here we describe an enhanced piezoresistive transduction mechanism based on the asymmetry of the beam shape at rest. We show that this mechanism enables highly sensitive linear detection of the vibration of low-resistivity silicon beams without the need of exceptionally large piezoresistive coefficients. The general application of this effect is demonstrated by detecting multiple-order modes of silicon nanowire resonators made by either top-down or bottom-up fabrication methods. These results reveal a promising approach for practical applications of the simplest mechanical resonators, facilitating its manufacturability by very large-scale integration technologies.

  7. Study of spatial signal transduction in bistable switches

    NASA Astrophysics Data System (ADS)

    Zhao, Qi; Yao, Cheng-Gui; Tang, Jun; Liu, Li-Wei

    2016-10-01

    Bistable switch modules are among the most important fundamental motifs in signal-transduction pathways. To better understand their spatial signal transduction, we model the diffusion process in the one-dimensional (1-D) domain. We find that when none of the elements diffuse, the response of the system exhibits a spatial switch-like property. However, when one of the elements is highly diffusible, the response of the system does not show any spatial switching behavior. Furthermore, we observe that the spatial responses of the system are more sensitive to the time constant of the switch when none of the elements are diffusible. Further, a slow loop keeps the system in the high steady state more positions than that in the fast loop. Finally, we consolidate our numerical results analytically by performing a mathematical method.

  8. The In Vitro Lipolysis of Lipid-Based Drug Delivery Systems: A Newly Identified Relationship between Drug Release and Liquid Crystalline Phase

    PubMed Central

    Xiao, Lu; Yi, Tao; Liu, Ying; Zhou, Hua

    2016-01-01

    The purpose of this study was to offer a new insight into the microstructure changes during in vitro lipolysis of five lipid-based drug delivery formulations belonging to different lipid formulation types. Five lipid-based formulations of indomethacin were investigated using an in vitro lipolysis model. During lipolysis, microstructures of the intermediate phase formed by lipolytic products were observed. The results showed that the time of liquid crystal formation during in vitro digestion for these formulations was Type I > Type II > Type IIIB > Type IV > Type IIIA (p < 0.05). After lipolysis, the drug releases from these formulations were determined. The results showed that the amount of drug distributed in the aqueous phase, obtained by ultracentrifuge after lipolysis, was, astonishingly, in inverse rank order of the above mentioned, that is, Type IIIA > Type IV > Type IIIB > Type II > Type I (p < 0.05). These results showed that the liquid crystalline phase probably has a critical influence on the fate of the drug during in vitro lipolysis and suggested that the liquid crystalline phase facilitated drug precipitation. These findings may improve the understanding of lipolysis of lipid-based drug delivery systems for designing better delivery system. PMID:27294110

  9. In vitro-in vivo evaluation of lipid based formulations of the CETP inhibitors CP-529,414 (torcetrapib) and CP-532,623.

    PubMed

    McEvoy, Claire L; Trevaskis, Natalie L; Edwards, Glenn A; Perlman, Michael E; Ambler, Catherine M; Mack, Mary C; Brockhurst, Barbara; Porter, Christopher J H

    2014-11-01

    The present study investigated the use of lipid based drug delivery systems to enhance the oral bioavailability of the CETP inhibitors CP-532,623 and torcetrapib. A series of self-emulsifying lipid based drug delivery systems (SEDDS) were assembled and examined using an in vitro lipid digestion model to evaluate patterns of drug precipitation under simulated intestinal conditions. Drug exposure after oral administration of the same formulations was subsequently assessed in beagle dogs. CP-532,623 was maintained in a solubilised state during dispersion of most formulations in simulated intestinal fluid, however, solubilisation capacity was reduced to various degrees upon in vitro digestion. Administration of SEDDS formulations to beagle dogs resulted in moderate differences in plasma AUC when compared to the differences in solubilisation observed in vitro. Similar trends were observed for torcetrapib. In all cases, however, in vivo exposure of CP-532,623 was greatly enhanced by administration in lipid based drug delivery systems when compared to a powder formulation. Some correlation between in vitro solubilisation and in vivo drug exposure (AUC) was evident; however, this was not linear. The data suggest that for highly lipophilic drugs such as CP-532,623 in vitro digestion data may be a conservative in vitro indicator of utility and that good exposure may be evident even for formulations that result in significant drug precipitation during in vitro digestion.

  10. Dynamic disorder and the energetic costs of information transduction

    SciTech Connect

    Thill, Peter

    2014-07-07

    We study a model of dynamic disorder relevant for signal transduction pathways in which enzymatic reaction rates fluctuate over several orders of magnitude. For the simple networks we consider, dynamic disorder drives the system far from equilibrium and imposes an energetic burden for high fidelity signaling capability. We study how the dynamics of the underlying stochastic behavior in the reaction rate process is related to the energetic cost of transmitting information through the network.

  11. Tuning piezoresistive transduction in nanomechanical resonators by geometrical asymmetries

    SciTech Connect

    Llobet, J.; Sansa, M.; Lorenzoni, M.; Pérez-Murano, F.; Borrisé, X.; San Paulo, A.

    2015-08-17

    The effect of geometrical asymmetries on the piezoresistive transduction in suspended double clamped beam nanomechanical resonators is investigated. Tapered silicon nano-beams, fabricated using a fast and flexible prototyping method, are employed to determine how the asymmetry affects the transduced piezoresistive signal for different mechanical resonant modes. This effect is attributed to the modulation of the strain in pre-strained double clamped beams, and it is confirmed by means of finite element simulations.

  12. Hypergravity signal transduction and gene expression in cultured mammalian cells

    NASA Technical Reports Server (NTRS)

    Kumei, Y.; Whitson, P. A.

    1994-01-01

    A number of studies have been conducted during space flight and with clinostats and centrifuges, suggesting that gravity effects the proliferation and differentiation of mammalian cells in vitro. However, little is known about the mechanisms by which mammalian cells respond to changes in gravitational stress. This paper summarizes studies designed to clarify the effects of hypergravity on the cultured human HeLa cells and to investigate the mechanism of hypergravity signal transduction in these cells.

  13. Soliton growth-signal transduction in topologically quantized T cells

    NASA Astrophysics Data System (ADS)

    Matsson, Leif

    1993-09-01

    A model for growth-signal transduction of the T cell and its growth factor, interleukin-2, is presented. It is obtained as a generalization of the usual rate equation and is founded on the observation that a definite number of receptor occupations must take place in order to promote transition to the S phase and subsequent DNA replication. The generalized rate equation is identified as the equation of motion of a Lagrangian field theory of Ginzburg-Landau (Goldstone) type. However it is not an ad hoc model but is a microscopic theory of the interaction of interleukin-2 and its receptor. The topological quantum number of the model is related to the observed definite number of receptor occupations required to elicit growth-signal transduction. Individual receptor quanta, up to this limit, are subjected to a type of Bose condensation. This collective excitation constitutes the growth signal in the form of a topological kink soliton which is then launched by the next potential receptor occupation that makes the interaction repulsive. The model provides a possible long-absent explanation of the triggering mechanism for growth-signal transduction by means of the ambivalent interaction, which switches sign after a definite number of receptor occupations. Moreover, it offers an explanation of how Nature screens out fractional signals in the growth-signal-transduction process of T cells. Although the model is derived for assumed point-like cells and certain other restrictions, the obtained dose-response curves are in striking agreement with proliferation data from studies of both the leukemic T cell line MLA-144 from gibbon ape and normal human T cells in, and without, the presence of monoclonal anti-Tac antibodies.

  14. Signal transduction and information processing in mammalian taste buds

    PubMed Central

    2013-01-01

    The molecular machinery for chemosensory transduction in taste buds has received considerable attention within the last decade. Consequently, we now know a great deal about sweet, bitter, and umami taste mechanisms and are gaining ground rapidly on salty and sour transduction. Sweet, bitter, and umami tastes are transduced by G-protein-coupled receptors. Salty taste may be transduced by epithelial Na channels similar to those found in renal tissues. Sour transduction appears to be initiated by intracellular acidification acting on acid-sensitive membrane proteins. Once a taste signal is generated in a taste cell, the subsequent steps involve secretion of neurotransmitters, including ATP and serotonin. It is now recognized that the cells responding to sweet, bitter, and umami taste stimuli do not possess synapses and instead secrete the neurotransmitter ATP via a novel mechanism not involving conventional vesicular exocytosis. ATP is believed to excite primary sensory afferent fibers that convey gustatory signals to the brain. In contrast, taste cells that do have synapses release serotonin in response to gustatory stimulation. The postsynaptic targets of serotonin have not yet been identified. Finally, ATP secreted from receptor cells also acts on neighboring taste cells to stimulate their release of serotonin. This suggests that there is important information processing and signal coding taking place in the mammalian taste bud after gustatory stimulation. PMID:17468883

  15. Hair-bundle friction from transduction channels' gating forces

    NASA Astrophysics Data System (ADS)

    Bormuth, Volker; Barral, Jérémie; Joanny, Jean-François; Jülicher, Frank; Martin, Pascal

    2015-12-01

    Hearing starts when sound-evoked mechanical vibrations of the hair-cell bundle activate mechanosensitive ion channels, giving birth to an electrical signal. As for any mechanical system, friction impedes movements of the hair bundle and thus constrains the sensitivity and frequency selectivity of auditory transduction. We have shown recently that the opening and closing of the transduction channels produce internal frictional forces that can dominate viscous drag on the micrometer-sized hair bundle and thus provide a major source of damping [2]. We develop here a physical theory of passive hair-bundle mechanics that explains the origin of channel friction. We show that channel friction can be understood quantitatively by coupling the dynamics of the conformational change associated with channel gating to tip-link tension. As a result, varying channel properties affects friction, with faster channels producing smaller friction. The analysis emphasizes the dual role of transduction channels' gating forces, which affect both hair-bundle stiffness and drag. Friction originating from gating of ion channels is a general concept that is relevant to all mechanosensitive channels.

  16. Key cancer cell signal transduction pathways as therapeutic targets.

    PubMed

    Bianco, Roberto; Melisi, Davide; Ciardiello, Fortunato; Tortora, Giampaolo

    2006-02-01

    Growth factor signals are propagated from the cell surface, through the action of transmembrane receptors, to intracellular effectors that control critical functions in human cancer cells, such as differentiation, growth, angiogenesis, and inhibition of cell death and apoptosis. Several kinases are involved in transduction pathways via sequential signalling activation. These kinases include transmembrane receptor kinases (e.g., epidermal growth factor receptor EGFR); or cytoplasmic kinases (e.g., PI3 kinase). In cancer cells, these signalling pathways are often altered and results in a phenotype characterized by uncontrolled growth and increased capability to invade surrounding tissue. Therefore, these crucial transduction molecules represent attractive targets for cancer therapy. This review will summarize current knowledge of key signal transduction pathways, that are altered in cancer cells, as therapeutic targets for novel selective inhibitors. The most advanced targeted agents currently under development interfere with function and expression of several signalling molecules, including the EGFR family; the vascular endothelial growth factor and its receptors; and cytoplasmic kinases such as Ras, PI3K and mTOR.

  17. Piezotransistive transduction of femtoscale displacement for photoacoustic spectroscopy.

    PubMed

    Talukdar, Abdul; Faheem Khan, M; Lee, Dongkyu; Kim, Seonghwan; Thundat, Thomas; Koley, Goutam

    2015-01-01

    Measurement of femtoscale displacements in the ultrasonic frequency range is attractive for advanced material characterization and sensing, yet major challenges remain in their reliable transduction using non-optical modalities, which can dramatically reduce the size and complexity of the transducer assembly. Here we demonstrate femtoscale displacement transduction using an AlGaN/GaN heterojunction field effect transistor-integrated GaN microcantilever that utilizes piezoelectric polarization-induced changes in two-dimensional electron gas to transduce displacement with very high sensitivity. The piezotransistor demonstrated an ultra-high gauge factor of 8,700 while consuming an extremely low power of 1.36 nW, and transduced external excitation with a superior noise-limited resolution of 12.43 fm Hz(-1/2) and an outstanding responsivity of 170 nV fm(-1), which is comparable to the optical transduction limits. These extraordinary characteristics, which enabled unique detection of nanogram quantity of analytes using photoacoustic spectroscopy, can be readily exploited in realizing a multitude of novel sensing paradigms. PMID:26258983

  18. State-time spectrum of signal transduction logic models

    NASA Astrophysics Data System (ADS)

    MacNamara, Aidan; Terfve, Camille; Henriques, David; Peñalver Bernabé, Beatriz; Saez-Rodriguez, Julio

    2012-08-01

    Despite the current wealth of high-throughput data, our understanding of signal transduction is still incomplete. Mathematical modeling can be a tool to gain an insight into such processes. Detailed biochemical modeling provides deep understanding, but does not scale well above relatively a few proteins. In contrast, logic modeling can be used where the biochemical knowledge of the system is sparse and, because it is parameter free (or, at most, uses relatively a few parameters), it scales well to large networks that can be derived by manual curation or retrieved from public databases. Here, we present an overview of logic modeling formalisms in the context of training logic models to data, and specifically the different approaches to modeling qualitative to quantitative data (state) and dynamics (time) of signal transduction. We use a toy model of signal transduction to illustrate how different logic formalisms (Boolean, fuzzy logic and differential equations) treat state and time. Different formalisms allow for different features of the data to be captured, at the cost of extra requirements in terms of computational power and data quality and quantity. Through this demonstration, the assumptions behind each formalism are discussed, as well as their advantages and disadvantages and possible future developments.

  19. Piezotransistive transduction of femtoscale displacement for photoacoustic spectroscopy.

    PubMed

    Talukdar, Abdul; Faheem Khan, M; Lee, Dongkyu; Kim, Seonghwan; Thundat, Thomas; Koley, Goutam

    2015-08-10

    Measurement of femtoscale displacements in the ultrasonic frequency range is attractive for advanced material characterization and sensing, yet major challenges remain in their reliable transduction using non-optical modalities, which can dramatically reduce the size and complexity of the transducer assembly. Here we demonstrate femtoscale displacement transduction using an AlGaN/GaN heterojunction field effect transistor-integrated GaN microcantilever that utilizes piezoelectric polarization-induced changes in two-dimensional electron gas to transduce displacement with very high sensitivity. The piezotransistor demonstrated an ultra-high gauge factor of 8,700 while consuming an extremely low power of 1.36 nW, and transduced external excitation with a superior noise-limited resolution of 12.43 fm Hz(-1/2) and an outstanding responsivity of 170 nV fm(-1), which is comparable to the optical transduction limits. These extraordinary characteristics, which enabled unique detection of nanogram quantity of analytes using photoacoustic spectroscopy, can be readily exploited in realizing a multitude of novel sensing paradigms.

  20. Piezotransistive transduction of femtoscale displacement for photoacoustic spectroscopy

    PubMed Central

    Talukdar, Abdul; Faheem Khan, M.; Lee, Dongkyu; Kim, Seonghwan; Thundat, Thomas; Koley, Goutam

    2015-01-01

    Measurement of femtoscale displacements in the ultrasonic frequency range is attractive for advanced material characterization and sensing, yet major challenges remain in their reliable transduction using non-optical modalities, which can dramatically reduce the size and complexity of the transducer assembly. Here we demonstrate femtoscale displacement transduction using an AlGaN/GaN heterojunction field effect transistor-integrated GaN microcantilever that utilizes piezoelectric polarization-induced changes in two-dimensional electron gas to transduce displacement with very high sensitivity. The piezotransistor demonstrated an ultra-high gauge factor of 8,700 while consuming an extremely low power of 1.36 nW, and transduced external excitation with a superior noise-limited resolution of 12.43 fm Hz−1/2 and an outstanding responsivity of 170 nV fm−1, which is comparable to the optical transduction limits. These extraordinary characteristics, which enabled unique detection of nanogram quantity of analytes using photoacoustic spectroscopy, can be readily exploited in realizing a multitude of novel sensing paradigms. PMID:26258983

  1. Signal transduction images in human brain by positron emission tomography

    SciTech Connect

    Imahori, Y.; Fujii, R.; Ueda, S.

    1994-05-01

    Analysis of changes in intracellular signal transduction will provide clear images of the projected target neurons. We have recently developed a technique which allows second-messenger imaging of changes in intracellular signal transduction which is activated in parallel with phosphoinositide (PI) turnover. Using carbon-11-labeled 1,2-diacylglycerol (DAG), we have recently succeeded in making an image of intracellular signal transduction during the course of synaptic transmission in human brains. When five healthy volunteers were examined by this technique, they had high activity in the associate field, in particular the prefrontal area. In the absence of paradigm loading, the associate field was unilaterally active, and human subjects showed predominant activity in the right prefrontal area. Activation of the ipsilateral supraorbital region and the superior temporal area was also seen at the same time. In conclusion, no previous study has directly demonstrated the unilateral predominance of the activity in the associate fields (projected target area) and the accompanying areas. Unlike the conventional positron-labeled compounds which did not permit visualization of activation of the associate fields, our technique can measure the PI turnover, as a postsynaptic response, and thus provide clear images of the projected target nerve cells in relation to higher cortical function in human brain.

  2. An Electrokinetic Model of Transduction in the Semicircular Canal

    PubMed Central

    O'Leary, Dennis P.

    1970-01-01

    Transduction in the semicircular canal was studied by focusing an infrared beam on either side of exposed ampullae from the posterior canals of Rana pipiens. The direction of fluid movement resulting from a stimulus was inferred by observing the polarity of the change in afferent impulse mean rate relative to the spontaneous value. On the basis of the accepted functional polarization of this receptor, the results indicate that fluid moved toward the warmer side of the ampulla. Convection and thermal reception were shown to be unlikely explanations for these results. Morover, cupular displacements toward the warmer side would not be expected. Because thermo-osmosis can cause fluid to move toward the warmer side in a gelatin membrane, the results can be interpreted as evidence that thermo-osmosis occurred in the gelatinous cupula and influenced the transduction mechanism. Thermo-osmosis of liquids appears to be due to an electric field that is set up in a charged membrane; hence, the hair cells might have detected an electric field that occurred in the cupula during thermo-osmosis. Electroreception might be an important link in the transduction of physiological stimuli also. Rotational stimuli could result in weak electric fields in the cupula by the mechanoelectric effect. Cupular displacements could be important for large stimuli, but extrapolations to threshold stimuli suggest displacements of angstrom amplitudes. Therefore, electroreception by the hair cells could be an explanation of the great sensitivity that has been observed in the semicircular canal and other labyrinthine receptors. PMID:5496906

  3. Sympathetic vascular transduction is augmented in young normotensive blacks

    NASA Technical Reports Server (NTRS)

    Ray, Chester A.; Monahan, Kevin D.

    2002-01-01

    The purpose of the present study was to determine sympathetic vascular transduction in young normotensive black and white adults. We hypothesized that blacks would demonstrate augmented transduction of muscle sympathetic nerve activity (MSNA) into vascular resistance. To test this hypothesis, MSNA, forearm blood flow, heart rate, and arterial blood pressure were measured during lower body negative pressure (LBNP). At rest, no differences existed in arterial blood pressure, heart rate, forearm blood flow, and forearm vascular resistance (FVR). Likewise, LBNP elicited comparable responses of these variables for blacks and whites. Baseline MSNA did not differ between blacks and whites, but whites demonstrated greater increases during LBNP (28 +/- 7 vs. 55 +/- 18%, 81 +/- 21 vs. 137 +/- 42%, 174 +/- 81 vs. 556 +/- 98% for -5, -15, and -40 mmHg LBNP, respectively; P < 0.001). Consistent with smaller increases in MSNA but similar FVR responses during LBNP, blacks demonstrated greater sympathetic vascular transduction (%FVR/%MSNA) than whites (0.95 +/- 0.07 vs. 0.82 +/- 0.07 U; 0.82 +/- 0.11 vs. 0.64 +/- 0.09 U; 0.95 +/- 0.37 vs. 0.35 +/- 0.09 U; P < 0.01). In summary, young whites demonstrate greater increases in MSNA during baroreceptor unloading than age-matched normotensive blacks. However, more importantly, for a given increase in MSNA, blacks demonstrate greater forearm vasoconstriction than whites. This finding may contribute to augmented blood pressure reactivity in blacks.

  4. Retinal transduction profiles by high-capacity viral vectors.

    PubMed

    Puppo, A; Cesi, G; Marrocco, E; Piccolo, P; Jacca, S; Shayakhmetov, D M; Parks, R J; Davidson, B L; Colloca, S; Brunetti-Pierri, N; Ng, P; Donofrio, G; Auricchio, A

    2014-10-01

    Retinal gene therapy with adeno-associated viral (AAV) vectors is safe and effective in humans. However, the limited cargo capacity of AAV prevents their use for therapy of those inherited retinopathies (IRs) due to mutations in large (>5 kb) genes. Viral vectors derived from adenovirus (Ad), lentivirus (LV) and herpes virus (HV) can package large DNA sequences, but do not target efficiently retinal photoreceptors (PRs) where the majority of genes responsible for IRs are expressed. Here, we have evaluated the mouse retinal transduction profiles of vectors derived from 16 different Ad serotypes, 7 LV pseudotypes and from a bovine HV. Most of the vectors tested transduced efficiently the retinal pigment epithelium. We found that LV-GP64 tends to transduce more PRs than the canonical LV-VSVG, albeit this was restricted to a narrow region. We observed more extensive PR transduction with HdAd1, 2 and 5/F35++ than with LV, although none of them outperformed the canonical HdAd5 or matched the extension of PR transduction achieved with AAV2/8.

  5. Retinal transduction profiles by high-capacity viral vectors

    PubMed Central

    Puppo, Agostina; Cesi, Giulia; Marrocco, Elena; Piccolo, Pasquale; Jacca, Sarah; Shayakhmetov, Dmitry M.; Parks, Robin J.; Davidson, Beverly L.; Colloca, Stefano; Brunetti-Pierri, Nicola; Ng, Philip; Donofrio, Gaetano; Auricchio, Alberto

    2014-01-01

    Retinal gene therapy with adeno-associated viral (AAV) vectors is safe and effective in humans. However, the limited cargo capacity of AAV prevents their use for therapy of those inherited retinopathies (IRs) due to mutations in large (>5kb) genes. Viral vectors derived from Adenovirus (Ad), Lentivirus (LV) and Herpesvirus (HV) can package large DNA sequences but do not target efficiently retinal photoreceptors (PRs) where the majority of genes responsible for IRs are expressed. Here, we have evaluated the mouse retinal transduction profiles of vectors derived from 16 different Ad serotypes, 7 LV pseudotypes, and from a bovine HV. Most of the vectors tested transduced efficiently the retinal pigment epithelium (RPE). We found that LV-GP64 tends to transduce more PRs than the canonical LV-VSVG albeit this was restricted to a narrow region. We observed more extensive PR transduction with HdAd1, 2 and 5/F35++ than with LV, although none of them outperformed the canonical HdAd5 or matched the extension of PR transduction achieved with AAV2/8. PMID:24989814

  6. Transduction in Streptomyces hygroscopicus mediated by the temperate bacteriophage SH10.

    PubMed

    Süss, F; Klaus, S

    1981-01-01

    The temperate actinophage SH10 mediates generalized transduction in Streptomyces hygroscopicus at low frequency. The efficiency of transduction depends on the average phage input, age of outgrowing spores of the recipient and on the selective marker. The highest EOT was found for the auxotrophic mutants 21(phe-) and 5(try-) (4.2 x 10(-6) and 2.7 x 10(-6), respectively). Transduction of the thermosensitive mutant NG14-216 ts 35 was two orders of magnitude lower (2.5 x 10(-8)). The transductant colonies segregated into stable and unstable clones. Stable transductants were never found to be lysogenic for phage SH10.

  7. Cation-Coupled Bicarbonate Transporters

    PubMed Central

    Aalkjaer, Christian; Boedtkjer, Ebbe; Choi, Inyeong; Lee, Soojung

    2016-01-01

    Cation-coupled HCO3− transport was initially identified in the mid-1970s when pioneering studies showed that acid extrusion from cells is stimulated by CO2/HCO3− and associated with Na+ and Cl− movement. The first Na+-coupled bicarbonate transporter (NCBT) was expression-cloned in the late 1990s. There are currently five mammalian NCBTs in the SLC4-family: the electrogenic Na,HCO3-cotransporters NBCe1 and NBCe2 (SLC4A4 and SLC4A5 gene products); the electroneutral Na,HCO3-cotransporter NBCn1 (SLC4A7 gene product); the Na+-driven Cl,HCO3-exchanger NDCBE (SLC4A8 gene product); and NBCn2/NCBE (SLC4A10 gene product), which has been characterized as an electroneutral Na,HCO3-cotransporter or a Na+-driven Cl,HCO3-exchanger. Despite the similarity in amino acid sequence and predicted structure among the NCBTs of the SLC4-family, they exhibit distinct differences in ion dependency, transport function, pharmacological properties, and interactions with other proteins. In epithelia, NCBTs are involved in transcellular movement of acid-base equivalents and intracellular pH control. In nonepithelial tissues, NCBTs contribute to intracellular pH regulation; and hence, they are crucial for diverse tissue functions including neuronal discharge, sensory neuron development, performance of the heart, and vascular tone regulation. The function and expression levels of the NCBTs are generally sensitive to intracellular and systemic pH. Animal models have revealed pathophysiological roles of the transporters in disease states including metabolic acidosis, hypertension, visual defects, and epileptic seizures. Studies are being conducted to understand the physiological consequences of genetic polymorphisms in the SLC4-members, which are associated with cancer, hypertension, and drug addiction. Here, we describe the current knowledge regarding the function, structure, and regulation of the mammalian cation-coupled HCO3− transporters of the SLC4-family. PMID:25428855

  8. Cationic Lipid-Nucleic Acid Complexes for Gene Delivery And Silencing: Pathways And Mechanisms for Plasmid Dna And Sirna

    SciTech Connect

    Ewert, K.K.; Zidovska, A.; Ahmad, A.; Bouxsein, N.F.; Evans, H.M.; McAllister, C.S.; Samuel, C.E.; Safinya, C.R.; /SLAC

    2012-07-17

    Motivated by the promises of gene therapy, there is great interest in developing non-viral lipid-based vectors for therapeutic applications due to their low immunogenicity, low toxicity, ease of production, and the potential of transferring large pieces of DNA into cells. In fact, cationic liposome (CL) based vectors are among the prevalent synthetic carriers of nucleic acids (NAs) currently used in gene therapy clinical trials worldwide. These vectors are studied both for gene delivery with CL-DNA complexes and gene silencing with CL-siRNA (short interfering RNA) complexes. However, their transfection efficiencies and silencing efficiencies remain low compared to those of engineered viral vectors. This reflects the currently poor understanding of transfection-related mechanisms at the molecular and self-assembled levels, including a lack of knowledge about interactions between membranes and double stranded NAs and between CL-NA complexes and cellular components. In this review we describe our recent efforts to improve the mechanistic understanding of transfection by CL-NA complexes, which will help to design optimal lipid-based carriers of DNA and siRNA for therapeutic gene delivery and gene silencing.

  9. Anionic Lipid Content Presents a Barrier to the Activity of ROMP-Based Synthetic Mimics of Protein Transduction Domains (PTDMs).

    PubMed

    Lis, Michael; Dorner, Franziska; Tew, Gregory N; Lienkamp, Karen

    2016-06-14

    Many biophysical studies of protein transduction domains (PTDs) and their synthetic mimics (PTDMs) focus on the interaction between the polycationic PTD(M) and anionic phospholipid surfaces. Most, but not all, of these studies suggest that these cation-anion interactions are vital for membrane activity. In this study, the effect of anionic lipid content on PTDM performance was examined for three ring-opening metathesis (ROMP)-based PTDMs with varying hydrophobicity. Using a series of dye-loaded vesicles with gradually increasing anionic lipid content, we saw that increased anionic lipid content inhibited dye release caused by these PTDMs. This result is the opposite of what was found in studies with poly- and oligo-arginine. While the effect is reduced for more hydrophobic PTDMs, it is observable even with the most hydrophobic PTDMs of our test panel. Additional experiments included dynamic light scattering and zeta potential measurements to measure size as a function of vesicle surface charge in the presence of increasing PTDM concentration and surface plasmon resonance spectroscopy to quantify binding between PTDMs and surface-bound lipid layers with varying anion content. The results from these measurements suggested that PTDM hydrophobicity, not cation-anion interactions, is the main driving force of the interaction between our PTDMs and the model membranes investigated. This suggests a model of interaction where surface association and membrane insertion are driven by PTDM hydrophobicity, while anionic lipid content serves primarily to "pin" the PTDM to the membrane surface and limit insertion. PMID:27182683

  10. Anionic Lipid Content Presents a Barrier to the Activity of ROMP-Based Synthetic Mimics of Protein Transduction Domains (PTDMs).

    PubMed

    Lis, Michael; Dorner, Franziska; Tew, Gregory N; Lienkamp, Karen

    2016-06-14

    Many biophysical studies of protein transduction domains (PTDs) and their synthetic mimics (PTDMs) focus on the interaction between the polycationic PTD(M) and anionic phospholipid surfaces. Most, but not all, of these studies suggest that these cation-anion interactions are vital for membrane activity. In this study, the effect of anionic lipid content on PTDM performance was examined for three ring-opening metathesis (ROMP)-based PTDMs with varying hydrophobicity. Using a series of dye-loaded vesicles with gradually increasing anionic lipid content, we saw that increased anionic lipid content inhibited dye release caused by these PTDMs. This result is the opposite of what was found in studies with poly- and oligo-arginine. While the effect is reduced for more hydrophobic PTDMs, it is observable even with the most hydrophobic PTDMs of our test panel. Additional experiments included dynamic light scattering and zeta potential measurements to measure size as a function of vesicle surface charge in the presence of increasing PTDM concentration and surface plasmon resonance spectroscopy to quantify binding between PTDMs and surface-bound lipid layers with varying anion content. The results from these measurements suggested that PTDM hydrophobicity, not cation-anion interactions, is the main driving force of the interaction between our PTDMs and the model membranes investigated. This suggests a model of interaction where surface association and membrane insertion are driven by PTDM hydrophobicity, while anionic lipid content serves primarily to "pin" the PTDM to the membrane surface and limit insertion.

  11. Method for encapsulating and isolating hazardous cations, medium for encapsulating and isolating hazardous cations

    DOEpatents

    Wasserman, Stephen R.; Anderson, Kenneth B.; Song, Kang; Yuchs, Steven E.; Marshall, Christopher L.

    1998-01-01

    A method for encapsulating hazardous cations is provided comprising supplying a pretreated substrate containing the cations; contacting the substrate with an organo-silane compound to form a coating on the substrate; and allowing the coating to cure. A medium for containing hazardous cations is also provided, comprising a substrate having ion-exchange capacity and a silane-containing coating on the substrate.

  12. Design of lipid-based delivery systems for improving lymphatic transport and bioavailability of delta-tocopherol and nobiletin

    NASA Astrophysics Data System (ADS)

    Xia, Chunxin

    Lymphatic drug transport can confer bioavailability advantage by avoiding the first-pass metabolism normally observed in the portal vein hepatic route. It was reported that long chain lipid-based delivery systems can stimulate the formation of chylomicron and thus promote the lymphatic transport of drugs. In this study, a novel delta-tocopherol (delta-T) loaded Solid Lipid Nanoparticle (SLN) system was developed to investigate its effect on promoting the lymphatic transport of delta-T. The delta-T SLN was prepared with hot melt emulsification method by using glyceryl behenate (compritol RTM888) as the lipid phase and lecithin (PC75) as the emulsifier. Formula configuration, processing condition and loading capacity were carefully optimized. Physicochemical properties (particle size, surface charge, morphology) were also characterized. Moreover, excellent stability of the developed delta-T SLN in the gastrointestinal environment was observed by using an in vitro digestion model. Further investigations of the SLN in stimulating delta-T lymphatic transport were performed on mice without cannulation. Compared with the control group (delta-T corn oil dispersion), much lower delta-T levels in both blood and liver indicated reduced portal vein and hepatic transport of delta-T in the form of SLN. On the other hand, significantly higher concentrations of delta-T were observed in thymus, a major lymphatic tissue, indicating improved lymphatic transport of delta-T with the SLN delivery system. Finally, the far less excreted delta-T level in feces further confirmed improved lymphatic transport and overall bioavailability of delta-T by using SLN system. Nobiletin (NOB), one of most abundant polymethoxyflavones (PMFs) found in Citrus genus, has a low solubility in both water and oil at ambient temperatures. Thus it tends to form crystals when the loading exceeds its saturation level in the carrier system. This character greatly impaired its bioavailability and application. To

  13. Exploring transduction mechanisms of protein transduction domains (PTDs) in living cells utilizing single-quantum dot tracking (SQT) technology.

    PubMed

    Suzuki, Yasuhiro

    2012-01-01

    Specific protein domains known as protein transduction domains (PTDs) can permeate cell membranes and deliver proteins or bioactive materials into living cells. Various approaches have been applied for improving their transduction efficacy. It is, therefore, crucial to clarify the entry mechanisms and to identify the rate-limiting steps. Because of technical limitations for imaging PTD behavior on cells with conventional fluorescent-dyes, how PTDs enter the cells has been a topic of much debate. Utilizing quantum dots (QDs), we recently tracked the behavior of PTD that was derived from HIV-1 Tat (TatP) in living cells at the single-molecule level with 7-nm special precision. In this review article, we initially summarize the controversy on TatP entry mechanisms; thereafter, we will focus on our recent findings on single-TatP-QD tracking (SQT), to identify the major sequential steps of intracellular delivery in living cells and to discuss how SQT can easily provide direct information on TatP entry mechanisms. As a primer for SQT study, we also discuss the latest findings on single particle tracking of various molecules on the plasma membrane. Finally, we discuss the problems of QDs and the challenges for the future in utilizing currently available QD probes for SQT. In conclusion, direct identification of the rate-limiting steps of PTD entry with SQT should dramatically improve the methods for enhancing transduction efficiency. PMID:22368485

  14. Cation exchange capacity of pine bark substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cation exchange capacity (CEC) is an important soil and substrate chemical property. It describes a substrate's ability to retain cation nutrients. Higher CEC values for a substrate generally result in greater amounts of nutrients retained in the substrate and available for plant uptake, and great...

  15. Tripodal Receptors for Cation and Anion Sensors

    PubMed Central

    Kuswandi, Bambang; Nuriman; Verboom, Willem; Reinhoudt, David N.

    2006-01-01

    This review discusses different types of artificial tripodal receptors for the selective recognition and sensing of cations and anions. Examples on the relationship between structure and selectivity towards cations and anions are described. Furthermore, their applications as potentiometric ion sensing are emphasised, along with their potential applications in optical sensors or optodes.

  16. Advancements in Anion Exchange Membrane Cations

    SciTech Connect

    Sturgeon, Matthew R.; Long, Hai; Park, Andrew M.; Pivovar, Bryan S.

    2015-10-15

    Anion-exchange membrane fuel cells (AME-FCs) are of increasingly popular interest as they enable the use of non-Pt fuel cell catalysts, the primary cost limitation of proton exchange membrane fuel cells. Benzyltrimethyl ammonium (BTMA) is the standard cation that has historically been utilized as the hydroxide conductor in AEMs. Herein we approach AEMs from two directions. First and foremost we study the stability of several different cations in a hydroxide solution at elevated temperatures. We specifically targeted BTMA and methoxy and nitro substituted BTMA. We've also studied the effects of adding an akyl spacer units between the ammonium cation and the phenyl group. In the second approach we use computational studies to predict stable ammonium cations, which are then synthesized and tested for stability. Our unique method to study cation stability in caustic conditions at elevated temperatures utilizes Teflon Parr reactors suitable for use under various temperatures and cation concentrations. NMR analysis was used to determine remaining cation concentrations at specific time points with GCMS analysis verifying product distribution. We then compare the experimental results with calculated modeling stabilities. Our studies show that the electron donating methoxy groups slightly increase stability (compared to that of BTMA), while the electron withdrawing nitro groups greatly decrease stability in base. These results give insight into possible linking strategies to be employed when tethering a BTMA like ammonium cation to a polymeric backbone; thus synthesizing an anion exchange membrane.

  17. Intracellular trafficking mechanism of cationic phospholipids including cationic liposomes in HeLa cells.

    PubMed

    Un, K; Sakai-Kato, K; Goda, Y

    2014-07-01

    The development of gene delivery methods is essential for the achievement of effective gene therapy. Elucidation of the intracellular transfer mechanism for cationic carriers is in progress, but there are few reports regarding the intracellular trafficking processes of the cationic phospholipids taken up into cells. In the present work, the trafficking processes of a cationic phospholipid (1,2-dioleoyl-3-trimethylammonium-propane, DOTAP) were investigated from intracellular uptake to extracellular efflux using cationic liposomes in vitro. Following intracellular transport of liposomes via endocytosis, DOTAP was localized in the endoplasmic reticulum, Golgi apparatus, and mitochondria. Moreover, the proteins involved in DOTAP intracellular trafficking and extracellular efflux were identified. In addition, helper lipids of cationic liposomes were found to partially affect this intracellulartrafficking. These findings might provide valuable information for designing cationic carriers and avoiding unexpected toxic side effects derived from cationic liposomal components.

  18. Cationic Bolaamphiphiles for Gene Delivery

    NASA Astrophysics Data System (ADS)

    Tan, Amelia Li Min; Lim, Alisa Xue Ling; Zhu, Yiting; Yang, Yi Yan; Khan, Majad

    2014-05-01

    Advances in medical research have shed light on the genetic cause of many human diseases. Gene therapy is a promising approach which can be used to deliver therapeutic genes to treat genetic diseases at its most fundamental level. In general, nonviral vectors are preferred due to reduced risk of immune response, but they are also commonly associated with low transfection efficiency and high cytotoxicity. In contrast to viral vectors, nonviral vectors do not have a natural mechanism to overcome extra- and intracellular barriers when delivering the therapeutic gene into cell. Hence, its design has been increasingly complex to meet challenges faced in targeting of, penetration of and expression in a specific host cell in achieving more satisfactory transfection efficiency. Flexibility in design of the vector is desirable, to enable a careful and controlled manipulation of its properties and functions. This can be met by the use of bolaamphiphile, a special class of lipid. Unlike conventional lipids, bolaamphiphiles can form asymmetric complexes with the therapeutic gene. The advantage of having an asymmetric complex lies in the different purposes served by the interior and exterior of the complex. More effective gene encapsulation within the interior of the complex can be achieved without triggering greater aggregation of serum proteins with the exterior, potentially overcoming one of the great hurdles faced by conventional single-head cationic lipids. In this review, we will look into the physiochemical considerations as well as the biological aspects of a bolaamphiphile-based gene delivery system.

  19. Reduced modeling of signal transduction – a modular approach

    PubMed Central

    Koschorreck, Markus; Conzelmann, Holger; Ebert, Sybille; Ederer, Michael; Gilles, Ernst Dieter

    2007-01-01

    Background Combinatorial complexity is a challenging problem in detailed and mechanistic mathematical modeling of signal transduction. This subject has been discussed intensively and a lot of progress has been made within the last few years. A software tool (BioNetGen) was developed which allows an automatic rule-based set-up of mechanistic model equations. In many cases these models can be reduced by an exact domain-oriented lumping technique. However, the resulting models can still consist of a very large number of differential equations. Results We introduce a new reduction technique, which allows building modularized and highly reduced models. Compared to existing approaches further reduction of signal transduction networks is possible. The method also provides a new modularization criterion, which allows to dissect the model into smaller modules that are called layers and can be modeled independently. Hallmarks of the approach are conservation relations within each layer and connection of layers by signal flows instead of mass flows. The reduced model can be formulated directly without previous generation of detailed model equations. It can be understood and interpreted intuitively, as model variables are macroscopic quantities that are converted by rates following simple kinetics. The proposed technique is applicable without using complex mathematical tools and even without detailed knowledge of the mathematical background. However, we provide a detailed mathematical analysis to show performance and limitations of the method. For physiologically relevant parameter domains the transient as well as the stationary errors caused by the reduction are negligible. Conclusion The new layer based reduced modeling method allows building modularized and strongly reduced models of signal transduction networks. Reduced model equations can be directly formulated and are intuitively interpretable. Additionally, the method provides very good approximations especially for

  20. Lentiviral vector-mediated transduction of goat undifferentiated spermatogonia.

    PubMed

    Abbasi, Hassan; Hosseini, Sayyed Morteza; Hajian, Mahdi; Nasiri, Zahra; Bahadorani, Mehrnoosh; Tahmoorespur, Mojtaba; Nasiri, Mohammad Reza; Nasr-Esfahani, Mohammad Hossein

    2015-12-01

    Recent studies show that spermatogonial stem cells (SSCs) are able to colonize and form mature spermatozoa following transplantation into germ cell depleted testes of recipient males. Therefore, efficient ways for enrichment and gene transfer into SSCs provides a powerful tool for production of transgenic animals. In order to adapt the technique to goats, three issues were addressed: (i) enrichment of the undifferentiated spermatogonia including SSCs using magnetic activated cell sorting (MACS), (ii) lentiviral vector-mediated transduction of an enhanced green fluorescent protein (EGFP) transgene into enriched cells, and (iii) transplantation of transduced undifferentiated spermatogonia into the germ cell depleted testes of immune-suppressed mice to assess for migration and colony formation ability. Enriched cells were transduced by lentiviral vectors and subsequently analyzed for expression of THY1, PLZF, VASA, UCHL1 and BCL6B genes. Cells were also analyzed for GFP and PLZF by flow cytometry. Enriched transduced cells were transplanted into germ cell depleted mice testis. Quantitative analysis of transcripts revealed that MACS-enrichment significantly increased the expression of SSC-characteristic genes THY1, PLZF, VASA, UCHL1 and BCL6B compared to non-enriched population (P≤0.05). EGFP transduction did not affect the expression levels of SSC-characteristic genes. Flow cytometry revealed that 72% of transduced-enriched cells were positive for EGFP. Finally, transduced-enriched goat SSCs could colonize within the cells into the seminiferous tubules of germ cell depleted recipient mice at higher frequency than non-enriched cells. The results indicated that enrichment of goat undifferentiated spermatogonia by magnetic-activated cell sorting for THY1 antibody combined with lentiviral vector-mediated transduction has the potential to be used for production of transgenic goats.

  1. Cationic phospholipids: structure transfection activity relationships

    SciTech Connect

    Koynova, Rumiana; Tenchov, Boris

    2010-01-18

    Synthetic cationic lipids are presently the most widely used non-viral gene carriers. Examined here is a particularly attractive cationic lipid class, triester phosphatidylcholines (PCs) exhibiting low toxicities and good transfection efficiency. Similarly to other cationic lipids, they form stable complexes (lipoplexes) with the polyanionic nucleic acids. A summary of studies on a set of {approx}30 cationic PCs reveals the existence of a strong, systematic dependence of their transfection efficiency on the lipid hydrocarbon chain structure: transfection activity increases with increase of chain unsaturation from 0 to 2 double bonds per lipid and decreases with increase of chain length in the range {approx}30-50 total number of chain carbon atoms. Maximum transfection was observed for ethyl phosphate PCs (EPCs) with monounsaturated 14:1 chains (total of 2 double bonds and 30 chain carbon atoms). Lipid phase behavior is known to depend strongly on the chain molecular structure and the above relationships thus substantiate a view that cationic PC phase propensities are an important determinant of their activity. Indeed, X-ray structural studies show that the rate of DNA release from lipoplexes as well as transfection activity well correlate with non-lamellar phase progressions observed in cationic PC mixtures with membrane lipids. These findings appear to be of considerable interest because, according to current views, key processes in lipid-mediated transfection such as lipoplex disassembly and DNA release within the cells are believed to take place upon cationic lipid mixing with cellular lipids.

  2. Deciphering Parameter Sensitivity in the BvgAS Signal Transduction.

    PubMed

    Mapder, Tarunendu; Talukder, Srijeeta; Chattopadhyay, Sudip; Banik, Suman K

    2016-01-01

    To understand the switching of different phenotypic phases of Bordetella pertussis, we propose an optimized mathematical framework for signal transduction through BvgAS two-component system. The response of the network output to the sensory input has been demonstrated in steady state. An analysis in terms of local sensitivity amplification characterizes the nature of the molecular switch. The sensitivity analysis of the model parameters within the framework of various correlation coefficients helps to decipher the contribution of the modular structure in signal propagation. Once classified, the model parameters are tuned to generate the behavior of some novel strains using simulated annealing, a stochastic optimization technique.

  3. Transduction of DNA information through water and electromagnetic waves.

    PubMed

    Montagnier, Luc; Del Giudice, Emilio; Aïssa, Jamal; Lavallee, Claude; Motschwiller, Steven; Capolupo, Antonio; Polcari, Albino; Romano, Paola; Tedeschi, Alberto; Vitiello, Giuseppe

    2015-01-01

    The experimental conditions by which electromagnetic signals (EMS) of low frequency can be emitted by diluted aqueous solutions of some bacterial and viral DNAs are described. That the recorded EMS and nanostructures induced in water carry the DNA information (sequence) is shown by retrieval of that same DNA by classical PCR amplification using the TAQ polymerase, including both primers and nucleotides. Moreover, such a transduction process has also been observed in living human cells exposed to EMS irradiation. These experiments suggest that coherent long-range molecular interaction must be present in water to observe the above-mentioned features. The quantum field theory analysis of the phenomenon is presented in this article.

  4. Umami taste in mice uses multiple receptors and transduction pathways

    PubMed Central

    Yasumatsu, Keiko; Ogiwara, Yoko; Takai, Shingo; Yoshida, Ryusuke; Iwatsuki, Ken; Torii, Kunio; Margolskee, Robert F; Ninomiya, Yuzo

    2012-01-01

    Non-technical summary The distinctive umami taste elicited by l-glutamate and some other amino acids is thought to be initiated by G-protein-coupled receptors, such as heteromers of taste receptor type 1, members 1 and 3, and metabotropic glutamate receptors 1 and 4. We demonstrate the existence of multiple types of glutamate-sensitive gustatory nerve fibres and the contribution of multiple receptors and transduction pathways to umami taste. Such multiple systems for umami taste may differentially contribute to the behavioural preference for glutamate and discriminability of glutamate taste. Abstract The distinctive umami taste elicited by l-glutamate and some other amino acids is thought to be initiated by G-protein-coupled receptors. Proposed umami receptors include heteromers of taste receptor type 1, members 1 and 3 (T1R1+T1R3), and metabotropic glutamate receptors 1 and 4 (mGluR1 and mGluR4). Multiple lines of evidence support the involvement of T1R1+T1R3 in umami responses of mice. Although several studies suggest the involvement of receptors other than T1R1+T1R3 in umami, the identity of those receptors remains unclear. Here, we examined taste responsiveness of umami-sensitive chorda tympani nerve fibres from wild-type mice and mice genetically lacking T1R3 or its downstream transduction molecule, the ion channel TRPM5. Our results indicate that single umami-sensitive fibres in wild-type mice fall into two major groups: sucrose-best (S-type) and monopotassium glutamate (MPG)-best (M-type). Each fibre type has two subtypes; one shows synergism between MPG and inosine monophosphate (S1, M1) and the other shows no synergism (S2, M2). In both T1R3 and TRPM5 null mice, S1-type fibres were absent, whereas S2-, M1- and M2-types remained. Lingual application of mGluR antagonists selectively suppressed MPG responses of M1- and M2-type fibres. These data suggest the existence of multiple receptors and transduction pathways for umami responses in mice. Information

  5. Bio-inspired signal transduction with heterogeneous networks of nanoscillators

    NASA Astrophysics Data System (ADS)

    Cervera, Javier; Manzanares, José A.; Mafé, Salvador

    2012-02-01

    Networks of single-electron transistors mimic some of the essential properties of neuron populations, because weak electrical signals trigger network oscillations with a frequency proportional to the input signal. Input potentials representing the pixel gray level of a grayscale image can then be converted into rhythms and the image can be recovered from these rhythms. Networks of non-identical nanoscillators complete the noisy transduction more reliably than identical ones. These results are important for signal processing schemes and could support recent studies suggesting that neuronal variability enhances the processing of biological information.

  6. Hedgehog Signal Transduction: Key Players, Oncogenic Drivers, and Cancer Therapy.

    PubMed

    Pak, Ekaterina; Segal, Rosalind A

    2016-08-22

    The Hedgehog (Hh) signaling pathway governs complex developmental processes, including proliferation and patterning within diverse tissues. These activities rely on a tightly regulated transduction system that converts graded Hh input signals into specific levels of pathway activity. Uncontrolled activation of Hh signaling drives tumor initiation and maintenance. However, recent entry of pathway-specific inhibitors into the clinic reveals mixed patient responses and thus prompts further exploration of pathway activation and inhibition. In this review, we share emerging insights into regulated and oncogenic Hh signaling, supplemented with updates on the development and use of Hh pathway-targeted therapies.

  7. Deciphering Parameter Sensitivity in the BvgAS Signal Transduction

    PubMed Central

    Mapder, Tarunendu; Talukder, Srijeeta; Chattopadhyay, Sudip; Banik, Suman K.

    2016-01-01

    To understand the switching of different phenotypic phases of Bordetella pertussis, we propose an optimized mathematical framework for signal transduction through BvgAS two-component system. The response of the network output to the sensory input has been demonstrated in steady state. An analysis in terms of local sensitivity amplification characterizes the nature of the molecular switch. The sensitivity analysis of the model parameters within the framework of various correlation coefficients helps to decipher the contribution of the modular structure in signal propagation. Once classified, the model parameters are tuned to generate the behavior of some novel strains using simulated annealing, a stochastic optimization technique. PMID:26812153

  8. The dynamic control of signal transduction networks in cancer cells.

    PubMed

    Kolch, Walter; Halasz, Melinda; Granovskaya, Marina; Kholodenko, Boris N

    2015-09-01

    Cancer is often considered a genetic disease. However, much of the enormous plasticity of cancer cells to evolve different phenotypes, to adapt to challenging microenvironments and to withstand therapeutic assaults is encoded by the structure and spatiotemporal dynamics of signal transduction networks. In this Review, we discuss recent concepts concerning how the rich signalling dynamics afforded by these networks are regulated and how they impinge on cancer cell proliferation, survival, invasiveness and drug resistance. Understanding this dynamic circuitry by mathematical modelling could pave the way to new therapeutic approaches and personalized treatments.

  9. Ion channels and the transduction of light signals

    NASA Technical Reports Server (NTRS)

    Spalding, E. P.; Evans, M. L. (Principal Investigator)

    2000-01-01

    Studies of biological light-sensing mechanisms are revealing important roles for ion channels. Photosensory transduction in plants is no exception. In this article, the evidence that ion channels perform such signal-transducing functions in the complex array of mechanisms that bring about plant photomorphogenesis will be reviewed and discussed. The examples selected for discussion range from light-gradient detection in unicellular algae to the photocontrol of stem growth in Arabidopsis. Also included is some discussion of the technical aspects of studies that combine electrophysiology and photobiology.

  10. Inositol trisphosphate, a novel second messenger in cellular signal transduction

    NASA Astrophysics Data System (ADS)

    Berridge, Michael J.; Irvine, Robin F.

    1984-11-01

    There has recently been rapid progress in understanding receptors that generate intracellular signals from inositol lipids. One of these lipids, phosphatidylinositol 4,5-bisphosphate, is hydrolysed to diacylglycerol and inositol trisphosphate as part of a signal transduction mechanism for controlling a variety of cellular processes including secretion, metabolism, phototransduction and cell proliferation. Diacylglycerol operates within the plane of the membrane to activate protein kinase C, whereas inositol trisphosphate is released into the cytoplasm to function as a second messenger for mobilizing intracellular calcium.

  11. Roles of lipid turnover in transmembrane signal transduction.

    PubMed

    Ganong, B R

    1991-11-01

    Cells of higher organisms respond to external stimuli with a cascade of intracellular biochemical events initiated by binding of a hormone, growth factor, or neurotransmitter to a specific cell surface receptor. Previously well-characterized signal transduction pathways involve cyclic nucleotides as intracellular second messengers. Over the past decade, increasing attention has been focused on other signaling pathways in which membrane lipids serve as second messengers or their precursors. This review describes current understanding of these pathways and points to recent discoveries likely to open new frontiers in the coming decade.

  12. Generalized transduction in the enterobacterial phytopathogen Erwinia chrysanthemi.

    PubMed

    Chatterjee, A K; Brown, M A

    1980-09-01

    Bacteriophages induced by mitomycin treatment of Erwinia chrysanthemi KS612 produced plaques on lawns of E. chrysanthemi EC183 and KS605. Bacteriophage Erch-12, purified from one such plaque, transferred an array of chromosomal genes (arg, leu, his, ser, thr, trp, ura) to appropriate recipient strains derived from E. chrysanthemi EC 183. Recombinants were formed in the absence of cellular contact between donor and recipient bacteria and in the presence of deoxyribonuclease. Ultraviolet irradiation of the bacteriophage stimulated transductional frequency. Linkage was detected in two-factor crosses between the loci thr and ser and between rif and ade; several closely linked mutations in ser were mapped with respect to thr.

  13. Cation distributions on rapidly solidified cobalt ferrite

    NASA Technical Reports Server (NTRS)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  14. Antibacterial properties of cationic steroid antibiotics.

    PubMed

    Savage, Paul B; Li, Chunhong; Taotafa, Uale; Ding, Bangwei; Guan, Qunying

    2002-11-19

    Cationic steroid antibiotics have been developed that display broad-spectrum antibacterial activity. These compounds are comprised of steroids appended with amine groups arranged to yield facially amphiphilic morphology. Examples of these antibiotics are highly bactericidal, while related compounds effectively permeabilize the outer membranes of Gram-negative bacteria sensitizing these organisms to hydrophobic antibiotics. Cationic steroid antibiotics exhibit various levels of eukaryote vs. prokaryote cell selectivity, and cell selectivity can be increased via charge recognition of prokaryotic cells. Studies of the mechanism of action of these antibiotics suggest that they share mechanistic aspects with cationic peptide antibiotics. PMID:12445638

  15. Antiviral effect of HPMPC (Cidofovir®), entrapped in cationic liposomes: in vitro study on MDBK cell and BHV-1 virus.

    PubMed

    Korvasová, Zina; Drašar, Lukáš; Mašek, Josef; Turánek Knotigová, Pavlína; Kulich, Pavel; Matiašovic, Ján; Kovařčík, Kamil; Bartheldyová, Eliška; Koudelka, Štěpán; Škrabalová, Michaela; Miller, Andrew D; Holý, Antonín; Ledvina, Miroslav; Turánek, Jaroslav

    2012-06-10

    We designed and synthesised a series of new cationic lipids based on spermine linked to various hydrophobic anchors. These lipids could be potentially useful for the preparation of stable cationic liposomes intended for the construction of drug targeting systems applicable in the field of anticancer/antiviral therapy, vaccine carriers, and vectors for the gene therapy. Low in vitro toxicity was found for these compounds, especially for LD1, in several cell lines. The delivery of both a fluorescence marker (calcein) and antiviral drugs into cells has been achieved owing to a large extent of internalization of cationic liposomes (labelled by Lyssamine-Rhodamine PE or fluorescein-PE) as demonstrated by fluorescent microscopy and quantified by flow cytometry. The bovine herpes virus type 1 (BHV-1) virus infection in vitro model using MDBK cells was employed to study the effect of the established antiviral drug HPMPC (Cidofovir®) developed by Prof. A. Holý. Inhibition of BHV-1 virus replication was studied by quantitative RT-PCR and confirmed by both Hoffman modulation contrast microscopy and transmission electron microscopy. We found that in vitro antiviral activity of HPMPC was significantly improved by formulation in cationic liposomes, which decreased the viral replication by about 2 orders of magnitude.

  16. Pharmacological Investigations of the Cellular Transduction Pathways Used by Cholecystokinin to Activate Nodose Neurons

    PubMed Central

    Zhao, Huan; Kinch, Dallas C.; Simasko, Steven M.

    2011-01-01

    Cholecystokinin (CCK) directly activates vagal afferent neurons resulting in coordinated gastrointestinal functions and satiation. In vitro, the effects of CCK on dissociated vagal afferent neurons are mediated via activation of the vanilloid family of transient receptor potential (TRPV) cation channels leading to membrane depolarization and an increase in cytosolic calcium. However, the cellular transduction pathway(s) involved in this process between CCK receptors and channel opening have not been identified. To address this question, we monitored CCK-induced cytosolic calcium responses in dissociated nodose neurons from rat in the presence or absence of reagents that interact with various intracellular signaling pathways. We found that the phospholipase C (PLC) inhibitor U-73122 significantly attenuated CCK-induced responses, whereas the inactive analog U-73433 had no effect. Responses to CCK were also cross-desensitized by a brief pretreatment with m-3M3FBS, a PLC stimulator. Together these observations strongly support the participation of PLC in the effects of CCK on vagal afferent neurons. In contrast, pharmacological antagonism of phospholipase A2, protein kinase A, and phosphatidylinositol 3-kinase revealed that they are not critical in the CCK-induced calcium response in nodose neurons. Further investigations of the cellular pathways downstream of PLC showed that neither protein kinase C (PKC) nor generation of diacylglycerol (DAG) or release of calcium from intracellular stores participates in the response to CCK. These results suggest that alteration of membrane phosphatidylinositol 4,5-bisphosphate (PIP2) content by PLC activity mediates CCK-induced calcium response and that this pathway may underlie the vagally-mediated actions of CCK to induce satiation and alter gastrointestinal functions. PMID:21664195

  17. Radiative ion-ion neutralization: a new gas-phase atmospheric pressure ion transduction mechanism.

    PubMed

    Davis, Eric J; Siems, William F; Hill, Herbert H

    2012-06-01

    All atmospheric pressure ion detectors, including photo ionization detectors, flame ionization detectors, electron capture detectors, and ion mobility spectrometers, utilize Faraday plate designs in which ionic charge is collected and amplified. The sensitivity of these Faraday plate ion detectors are limited by thermal (Johnson) noise in the associated electronics. Thus approximately 10(6) ions per second are required for a minimal detection. This is not the case for ion detection under vacuum conditions where secondary electron multipliers (SEMs) can be used. SEMs produce a cascade of approximately 10(6) electrons per ion impinging on the conversion dynode. Similarly, photomultiplier tubes (PMTs) can generate approximately 10(6) electrons per photon. Unlike SEMs, however, PMTs are evacuated and sealed so that they are commonly used under atmospheric pressure conditions. This paper describes an atmospheric pressure ion detector based on coupling a PMT with light emitted from ion-ion neutralization reactions. The normal Faraday plate collector electrode was replaced with an electrode "needle" used to concentrate the anions as they were drawn to the tip of the needle by a strong focusing electric field. Light was emitted near the surface of the electrode when analyte ions were neutralized with cations produced from the anode. Although radiative-ion-ion recombination has been previously reported, this is the first time ions from separate ionization sources have been combined to produce light. The light from this radiative-ion-ion-neutralization (RIIN) was detected using a photon multiplier such that an ion mobility spectrum was obtained by monitoring the light emitted from mobility separated ions. An IMS spectrum of nitroglycerin (NG) was obtained utilizing RIIN for tranducing the mobility separated ions into an analytical signal. The implications of this novel ion transduction method are the potential for counting ions at atmospheric pressure and for obtaining ion

  18. Phosphoglycerolipids are master players in plant hormone signal transduction.

    PubMed

    Janda, Martin; Planchais, Severine; Djafi, Nabila; Martinec, Jan; Burketova, Lenka; Valentova, Olga; Zachowski, Alain; Ruelland, Eric

    2013-06-01

    Phosphoglycerolipids are essential structural constituents of membranes and some also have important cell signalling roles. In this review, we focus on phosphoglycerolipids that are mediators in hormone signal transduction in plants. We first describe the structures of the main signalling phosphoglycerolipids and the metabolic pathways that generate them, namely the phospholipase and lipid kinase pathways. In silico analysis of Arabidopsis transcriptome data provides evidence that the genes encoding the enzymes of these pathways are transcriptionally regulated in responses to hormones, suggesting some link with hormone signal transduction. The involvement of phosphoglycerolipid signalling in the early responses to abscisic acid, salicylic acid and auxins is then detailed. One of the most important signalling lipids in plants is phosphatidic acid. It can activate or inactivate protein kinases and/or protein phosphatases involved in hormone signalling. It can also activate NADPH oxidase leading to the production of reactive oxygen species. We will interrogate the mechanisms that allow the activation/deactivation of the lipid pathways, in particular the roles of G proteins and calcium. Mediating lipids thus appear as master players of cell signalling, modulating, if not controlling, major transducing steps of hormone signals.

  19. Gravity perception and signal transduction in single cells

    NASA Astrophysics Data System (ADS)

    Block, I.; Wolke, A.; Briegleb, W.; Ivanova, K.

    Cellular signal processing in multi-, as well as in unicellular organisms, has to rely on fundamentally similar mechanisms. Free-living single cells often use the gravity vector for their spatial orientation (gravitaxis) and show distinct gravisensitivities. In this investigation the gravisensitive giant ameboid cell Physarum polycephalum (Myxomycetes, acellular slime molds) is used. Its gravitaxis and the modulation of its intrinsic rhythmic contraction activity by gravity was demonstrated in 180 °turn experiments and in simulated, as well as in actual, near-weightlessness studies (fast-rotating clinostat; Spacelab D1, IML-1). The stimulus perception was addressed in an IML-2 experiment, which provided information on the gravireceptor itself by the determination of the cell's acceleration-sensitivity threshold. Ground-based experiments designed to elucidate the subsequent steps in signal transduction leading to a motor response, suggest that an acceleration stimulus induces changes in the level of second messenger, adenosine 3',5'-cyclic monophosphate (cAMP), indicating also that the acceleration-stimulus signal transduction chain of Physarum uses an ubiquitous second messenger pathway.

  20. The control of specificity in guard cell signal transduction

    PubMed Central

    Hetherington, A. M.

    1998-01-01

    Stomatal guard cells have proven to be an attractive system for dissecting the mechanisms of stimulus-response coupling in plants. In this review we focus on the intracellular signal transduction pathways by which extracellular signals bring about closure and opening of the stomatal pore. It is proposed that guard cell signal transduction pathways may be organized into functional arrays or signalling cassettes that contain elements common to a number of converging signalling pathways. The purpose of these signalling cassettes may be to funnel extracellular signals down onto the ion transporters that control the fluxes of ions that underlie stomatal movements. Evidence is emerging that specificity in guard cell signalling may be, in part, encoded in complex spatio-temporal patterns of increases in the concentration of cytosolic-free calcium ([Ca2+]cyt). It is suggested that oscillations in [Ca2+]cyt may generate calcium signatures that encode information concerning the stimulus type and strength. New evidence is presented that suggests that these calcium signatures may integrate information when many stimuli are present.

  1. Abscisic acid perception and signaling transduction in strawberry

    PubMed Central

    Li, Chunli; Jia, Haifeng; Chai, Yemao; Shen, Yuanyue

    2011-01-01

    On basis of fruit differential respiration and ethylene effects, climacteric and non-climacteric fruits have been classically defined. Over the past decades, the molecular mechanisms of climacteric fruit ripening were abundantly described and found to focus on ethylene perception and signaling transduction. In contrast, until our most recent breakthroughs, much progress has been made toward understanding the signaling perception and transduction mechanisms for abscisic acid (ABA) in strawberry, a model for non-climacteric fruit ripening. Our reports not only have provided several lines of strong evidences for ABA-regulated ripening of strawberry fruit, but also have demonstrated that homology proteins of Arabidopsis ABA receptors, including PYR/PYL/RCAR and ABAR/CHLH, act as positive regulators of ripening in response to ABA. These receptors also trigger a set of ABA downstream signaling components, and determine significant changes in the expression levels of both sugar and pigment metabolism-related genes that are closely associated with ripening. Soluble sugars, especially sucrose, may act as a signal molecular to trigger ABA accumulation through an enzymatic action of 9-cis-epoxycarotenoid dioxygenase 1 (FaNCED1). This mini-review offers an overview of these processes and also outlines the possible, molecular mechanisms for ABA in the regulation of strawberry fruit ripening through the ABA receptors. PMID:22095148

  2. Analysis and logical modeling of biological signaling transduction networks

    NASA Astrophysics Data System (ADS)

    Sun, Zhongyao

    The study of network theory and its application span across a multitude of seemingly disparate fields of science and technology: computer science, biology, social science, linguistics, etc. It is the intrinsic similarities embedded in the entities and the way they interact with one another in these systems that link them together. In this dissertation, I present from both the aspect of theoretical analysis and the aspect of application three projects, which primarily focus on signal transduction networks in biology. In these projects, I assembled a network model through extensively perusing literature, performed model-based simulations and validation, analyzed network topology, and proposed a novel network measure. The application of network modeling to the system of stomatal opening in plants revealed a fundamental question about the process that has been left unanswered in decades. The novel measure of the redundancy of signal transduction networks with Boolean dynamics by calculating its maximum node-independent elementary signaling mode set accurately predicts the effect of single node knockout in such signaling processes. The three projects as an organic whole advance the understanding of a real system as well as the behavior of such network models, giving me an opportunity to take a glimpse at the dazzling facets of the immense world of network science.

  3. Graviperception in ciliates: steps in the transduction chain

    NASA Astrophysics Data System (ADS)

    Hemmersbach, R.; Krause, M.; Bräucker, R.; Ivanova, K.

    Due to their clear gravity-induced behavioural responses (gravitaxis and gravikinesis) ciliates represent suitable model systems to study the mechanisms of gravity perception and signal transduction. While the development of distinct gravisensory organelles is the exception in ciliates (e.g. mueller organelles in Loxodes), a common strategy seems to be that the whole cytoplasm acts as statolith stimulating mechanosensitive ion channels in the cell membrane. In order to test this hypothesis, electrophysiological studies were performed, revealing the proposed changes (de- or hyperpolarizations) depending on the cell's (Stylonychia mytilus) spatial orientation. In order to test the involvement of second messengers in the gravity-signal transduction-chain, cAMP levels of Paramecium were measured under altered gravitational stimulation (TEXUS 37; centrifuge). We found a decrease in cAMP in microgravity and an increase in hypergravity (5 x g) compared to the 1 x g controls. Furthermore, the behaviour of Paramecium and Stylonychia was analyzed during the variable acceleration conditions of parabolic flights (5th German Parabolic Flight Campaign) and compared to data already known from TEXUS, MAXUS, and drop facilities (ZARM, JAMIC). The feasibility of parabolic flights with respect to threshold determination will be discussed.

  4. Alteration of EGFR Spatiotemporal Dynamics Suppresses Signal Transduction

    PubMed Central

    Turk, Harmony F.; Barhoumi, Rola; Chapkin, Robert S.

    2012-01-01

    The epidermal growth factor receptor (EGFR), which regulates cell growth and survival, is integral to colon tumorigenesis. Lipid rafts play a role in regulating EGFR signaling, and docosahexaenoic acid (DHA) is known to perturb membrane domain organization through changes in lipid rafts. Therefore, we investigated the mechanistic link between EGFR function and DHA. Membrane incorporation of DHA into immortalized colonocytes altered the lateral organization of EGFR. DHA additionally increased EGFR phosphorylation but paradoxically suppressed downstream signaling. Assessment of the EGFR-Ras-ERK1/2 signaling cascade identified Ras GTP binding as the locus of the DHA-induced disruption of signal transduction. DHA also antagonized EGFR signaling capacity by increasing receptor internalization and degradation. DHA suppressed cell proliferation in an EGFR-dependent manner, but cell proliferation could be partially rescued by expression of constitutively active Ras. Feeding chronically-inflamed, carcinogen-injected C57BL/6 mice a fish oil containing diet enriched in DHA recapitulated the effects on the EGFR signaling axis observed in cell culture and additionally suppressed tumor formation. We conclude that DHA-induced alteration in both the lateral and subcellular localization of EGFR culminates in the suppression of EGFR downstream signal transduction, which has implications for the molecular basis of colon cancer prevention by DHA. PMID:22761867

  5. Dual-transduction-mode sensing approach for chemical detection

    SciTech Connect

    Wang, Liang; Swensen, James S.

    2012-11-01

    Smart devices such as electronic nose have been developed for application in many fields like national security, defense, environmental regulation, health care, pipeline monitoring and food analysis. Despite a large array of individual sensors, these devices still lack the ability to identify a target at a very low concentration out of a mixture of odors, limited by a single type of transduction as the sensing response to distinguish one odor from another. Here, we propose a new sensor architecture empowering each individual sensor with multi-dimensional transduction signals. The resolving power of our proposed electronic nose is thereby multiplied by a set of different and independent variables which synergistically will provide a unique combined fingerprint for each analyte. We demonstrate this concept using a Light Emitting Organic Field-Effect Transistor (LEOFET). Sensing response has been observed on both electrical and optical output signals from a green LEOFET upon exposure to an explosive taggant, with optical signal exhibiting much higher sensitivity. This new sensor architecture opens a field of devices for smart detection of chemical and biological targets.

  6. Cationic ruthenium alkylidene catalysts bearing phosphine ligands.

    PubMed

    Endo, Koji; Grubbs, Robert H

    2016-02-28

    The discovery of highly active catalysts and the success of ionic liquid immobilized systems have accelerated attention to a new class of cationic metathesis catalysts. We herein report the facile syntheses of cationic ruthenium catalysts bearing bulky phosphine ligands. Simple ligand exchange using silver(i) salts of non-coordinating or weakly coordinating anions provided either PPh3 or chelating Ph2P(CH2)nPPh2 (n = 2 or 3) ligated cationic catalysts. The structures of these newly reported catalysts feature unique geometries caused by ligation of the bulky phosphine ligands. Their activities and selectivities in standard metathesis reactions were also investigated. These cationic ruthenium alkylidene catalysts reported here showed moderate activity and very similar stereoselectivity when compared to the second generation ruthenium dichloride catalyst in ring-closing metathesis, cross metathesis, and ring-opening metathesis polymerization assays.

  7. Genetic Analysis of Gravity Signal Transduction in Arabidopsis Roots

    NASA Astrophysics Data System (ADS)

    Masson, Patrick; Strohm, Allison; Barker, Richard; Su, Shih-Heng

    Like most other plant organs, roots use gravity as a directional guide for growth. Specialized cells within the columella region of the root cap (the statocytes) sense the direction of gravity through the sedimentation of starch-filled plastids (amyloplasts). Amyloplast movement and/or pressure on sensitive membranes triggers a gravity signal transduction pathway within these cells, which leads to a fast transcytotic relocalization of plasma-membrane associated auxin-efflux carrier proteins of the PIN family (PIN3 and PIN7) toward the bottom membrane. This leads to a polar transport of auxin toward the bottom flank of the cap. The resulting lateral auxin gradient is then transmitted toward the elongation zones where it triggers a curvature that ultimately leads to a restoration of vertical downward growth. Our laboratory is using strategies derived from genetics and systems biology to elucidate the molecular mechanisms that modulate gravity sensing and signal transduction in the columella cells of the root cap. Our previous research uncovered two J-domain-containing proteins, ARG1 and ARL2, as contributing to this process. Mutations in the corresponding paralogous genes led to alterations of root and hypocotyl gravitropism accompanied by an inability for the statocytes to develop a cytoplasmic alkalinization, relocalize PIN3, and transport auxin laterally, in response to gravistimulation. Both proteins are associated peripherally to membranes belonging to various compartments of the vesicular trafficking pathway, potentially modulating the trafficking of defined proteins between plasma membrane and endosomes. MAR1 and MAR2, on the other end, are distinct proteins of the plastidic outer envelope protein import TOC complex (the transmembrane channel TOC75 and the receptor TOC132, respectively). Mutations in the corresponding genes enhance the gravitropic defects of arg1. Using transformation-rescue experiments with truncated versions of TOC132 (MAR2), we have shown

  8. Genetic analysis of gravity signal transduction in roots

    NASA Astrophysics Data System (ADS)

    Masson, Patrick; Strohm, Allison; Baldwin, Katherine

    To grow downward into the soil, roots use gravity as a guide. Specialized cells, named stato-cytes, enable this directional growth response by perceiving gravity. Located in the columella region of the cap, these cells sense a reorientation of the root within the gravity field through the sedimentation of, and/or tension/pressure exerted by, dense amyloplasts. This process trig-gers a gravity signal transduction pathway that leads to a fast alkalinization of the cytoplasm and a change in the distribution of the plasma membrane-associated auxin-efflux carrier PIN3. The latter protein is uniformly distributed within the plasma membrane on all sides of the cell in vertically oriented roots. However, it quickly accumulates at the bottom side upon gravis-timulation. This process correlates with a preferential transport of auxin to the bottom side of the root cap, resulting in a lateral gradient across the tip. This gradient is then transported to the elongation zone where it promotes differential cellular elongation, resulting in downward curvature. We isolated mutations that affect gravity signal transduction at a step that pre-cedes cytoplasmic alkalinization and/or PIN3 relocalization and lateral auxin transport across the cap. arg1 and arl2 mutations identify a common genetic pathway that is needed for all three gravity-induced processes in the cap statocytes, indicating these genes function early in the pathway. On the other hand, adk1 affects gravity-induced PIN3 relocalization and lateral auxin transport, but it does not interfere with cytoplasmic alkalinization. ARG1 and ARL2 encode J-domain proteins that are associated with membranes of the vesicular trafficking path-way whereas ADK1 encodes adenosine kinase, an enzyme that converts adenosine derived from nucleic acid metabolism and the AdoMet cycle into AMP, thereby alleviating feedback inhibi-tion of this important methyl-donor cycle. Because mutations in ARG1 (and ARL2) do not completely eliminate

  9. Test procedure for cation exchange chromatography

    SciTech Connect

    Cooper, T.D.

    1994-08-24

    The purpose of this test plan is to demonstrate the synthesis of inorganic antimonate ion exchangers and compare their performance against the standard organic cation exchangers. Of particular interest is the degradation rate of both inorganic and organic cation exchangers. This degradation rate will be tracked by determining the ion exchange capacity and thermal stability as a function of time, radiation dose, and chemical reaction.

  10. Method for encapsulating and isolating hazardous cations, medium for encapsulating and isolating hazardous cations

    DOEpatents

    Wasserman, S.R.; Anderson, K.B.; Song, K.; Yuchs, S.E.; Marshall, C.L.

    1998-04-28

    A method for encapsulating hazardous cations is provided comprising supplying a pretreated substrate containing the cations; contacting the substrate with an organo-silane compound to form a coating on the substrate; and allowing the coating to cure. A medium for containing hazardous cations is also provided, comprising a substrate having ion-exchange capacity and a silane-containing coating on the substrate. 3 figs.

  11. Patterned Thread-like Micelles and DNA-Tethered Nanoparticles: A Structural Study of PEGylated Cationic Liposome–DNA Assemblies

    PubMed Central

    Majzoub, Ramsey N.; Ewert, Kai K.; Jacovetty, Erica L.; Carragher, Bridget; Potter, Clinton S.; Li, Youli; Safinya, Cyrus R.

    2015-01-01

    The self-assembly of oppositely charged biomacromolecules has been extensively studied due to its pertinence in the design of functional nanomaterials. Using cryo electronic microscopy (cryo-EM), optical light scattering and fluorescence microscopy, we investigated the structure and phase behavior of PEGylated (PEG: poly(ethylene-glycol)) cationic liposome–DNA nanoparticles (CL–DNA NPs) as a function of DNA length, topology (linear and circular) and ρchg (the molar charge ratio of cationic lipid to anionic DNA). Although all NPs studied showed a lamellar internal nanostructure, NPs formed with short (~ 2 kbps), linear, polydisperse DNA were defect-rich and contained smaller domains. Unexpectedly, we found distinctly different equilibrium structures away from the isoelectric point. At ρchg > 1, in the excess cationic lipid regime, thread-like micelles rich in PEG-lipid were found to coexist with NPs, cationic liposomes and spherical micelles. At high concentrations these PEGylated thread-like micelles formed a well-ordered, patterned morphology with highly uniform inter-micellar spacing. At ρchg < 1, in the excess DNA regime and with no added salt, individual NPs were tethered together via long, linear DNA (48 kbps λ-phage DNA) into a biopolymer-mediated floc. Our results provide insight on what equilibrium nanostructures can form when oppositely charged macromolecules self-assemble in aqueous media. Self-assembled, well-ordered thread-like micelles and tethered nanoparticles may have a broad range of applications in bionanotechnology, including nanoscale lithograpy and the development of lipid-based multi-functional nanoparticle networks. PMID:26048043

  12. Cloning and first functional characterization of a plant cyclic nucleotide-gated cation channel

    SciTech Connect

    Leng, Q.; Mercier, R.W.; Yao, W.; Berkowitz, G.A.

    1999-11-01

    Cyclic nucleotide-gated (cng) non-selective cation channels have been cloned from a number of animal systems. These channels are characterized by direct gating upon cAMO or cGMO binding to the intracellular portion of the channel protein, which leads to an increase in channel conductance. Animal cng channels are involved in signal transduction systems; they translate stimulus-induced changes in cytosolic cyclic nucleotide into altered cell membrane potential and/or cation flux as part of a signal cascade pathway. Putative plant homologs of animal cng channels have been identified. However, functional characterization (i.e., demonstration of cyclic-nucleotide-dependent ion currents) of a plant cng channel has not yet been accomplished. The authors report the cloning and first functional characterization of a plant member of this family of ion channels. The Arabidopsis cDNA AtCNGC2 encodes a polypeptide with deduced homology to the {alpha}-subunit of animal channels, and facilitates cyclic nucleotide-dependent cation currents upon expression in a number of heterologous systems. AtCNGC2 expression in a yeast mutant lacking a low-affinity K{sup +} uptake system complements growth inhibition only when lipophilic nucleotides are present in the culture medium. Voltage clamp analysis indicates that Xenopus lawvis oocytes injected with AtCNGC2 cRNA demonstrate cyclic-nucleotide-dependent, inward-rectifying K{sup +} currents. Human embryonic kidney cells (HEK293) transfected with AtCNGC2 cDNA demonstrate increased permeability to Ca{sup 2+} only in the presence of lipophilic cyclic nucleotides. The evidence presented here supports the functional classification of AtCNGC2 as a cyclic-nucleotide-gated cation channel, and presents the first direct evidence identifying a plant member of this ion channel family.

  13. Divalent cation shrinks DNA but inhibits its compaction with trivalent cation.

    PubMed

    Tongu, Chika; Kenmotsu, Takahiro; Yoshikawa, Yuko; Zinchenko, Anatoly; Chen, Ning; Yoshikawa, Kenichi

    2016-05-28

    Our observation reveals the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA 166 kbp) by fluorescence microscopy. It was found that divalent cations, Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. As the control experiment, we have confirmed the minimum effect of monovalent cation, Na(+) on the DNA higher-order structure. We interpret the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counterions. For the compaction with SPD(3+), we consider the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly charged polyelectrolyte, double-stranded DNA, by the 3+ cations. In contrast, the presence of 2+ cation decreases the gain of entropy contribution by the ion-exchange between monovalent and 3+ ions. PMID:27250329

  14. Divalent cation shrinks DNA but inhibits its compaction with trivalent cation

    NASA Astrophysics Data System (ADS)

    Tongu, Chika; Kenmotsu, Takahiro; Yoshikawa, Yuko; Zinchenko, Anatoly; Chen, Ning; Yoshikawa, Kenichi

    2016-05-01

    Our observation reveals the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA 166 kbp) by fluorescence microscopy. It was found that divalent cations, Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. As the control experiment, we have confirmed the minimum effect of monovalent cation, Na(+) on the DNA higher-order structure. We interpret the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counterions. For the compaction with SPD(3+), we consider the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly charged polyelectrolyte, double-stranded DNA, by the 3+ cations. In contrast, the presence of 2+ cation decreases the gain of entropy contribution by the ion-exchange between monovalent and 3+ ions.

  15. Dissolution of Lipid-Based Matrices in Simulated Gastrointestinal Solutions to Evaluate Their Potential for the Encapsulation of Bioactive Ingredients for Foods

    PubMed Central

    Champagne, Claude P.

    2014-01-01

    The goal of the study was to compare the dissolution of chocolate to other lipid-based matrices suitable for the microencapsulation of bioactive ingredients in simulated gastrointestinal solutions. Particles having approximately 750 μm or 2.5 mm were prepared from the following lipid-based matrices: cocoa butter, fractionated palm kernel oil (FPKO), chocolate, beeswax, carnauba wax, and paraffin. They were added to solutions designed to simulate gastric secretions (GS) or duodenum secretions (DS) at 37°C. Paraffin, carnauba wax, and bees wax did not dissolve in either the GS or DS media. Cocoa butter, FPKO, and chocolate dissolved in the DS medium. Cocoa butter, and to a lesser extent chocolate, also dissolved in the GS medium. With chocolate, dissolution was twice as fast as that with small particles (750 μm) as compared to the larger (2.5 mm) ones. With 750 μm particle sizes, 90% dissolution of chocolate beads was attained after only 60 minutes in the DS medium, while it took 120 minutes for 70% of FPKO beads to dissolve in the same conditions. The data are discussed from the perspective of controlled release in the gastrointestinal tract of encapsulated ingredients (minerals, oils, probiotic bacteria, enzymes, vitamins, and peptides) used in the development of functional foods. PMID:26904647

  16. Dissolution of Lipid-Based Matrices in Simulated Gastrointestinal Solutions to Evaluate Their Potential for the Encapsulation of Bioactive Ingredients for Foods.

    PubMed

    Raymond, Yves; Champagne, Claude P

    2014-01-01

    The goal of the study was to compare the dissolution of chocolate to other lipid-based matrices suitable for the microencapsulation of bioactive ingredients in simulated gastrointestinal solutions. Particles having approximately 750 μm or 2.5 mm were prepared from the following lipid-based matrices: cocoa butter, fractionated palm kernel oil (FPKO), chocolate, beeswax, carnauba wax, and paraffin. They were added to solutions designed to simulate gastric secretions (GS) or duodenum secretions (DS) at 37°C. Paraffin, carnauba wax, and bees wax did not dissolve in either the GS or DS media. Cocoa butter, FPKO, and chocolate dissolved in the DS medium. Cocoa butter, and to a lesser extent chocolate, also dissolved in the GS medium. With chocolate, dissolution was twice as fast as that with small particles (750 μm) as compared to the larger (2.5 mm) ones. With 750 μm particle sizes, 90% dissolution of chocolate beads was attained after only 60 minutes in the DS medium, while it took 120 minutes for 70% of FPKO beads to dissolve in the same conditions. The data are discussed from the perspective of controlled release in the gastrointestinal tract of encapsulated ingredients (minerals, oils, probiotic bacteria, enzymes, vitamins, and peptides) used in the development of functional foods.

  17. Studies on the lipase-induced degradation of lipid-based drug delivery systems. Part II - Investigations on the mechanisms leading to collapse of the lipid structure.

    PubMed

    Schwab, Martin; McGoverin, Cushla M; Gordon, Keith C; Winter, Gerhard; Rades, Thomas; Myschik, Julia; Strachan, Clare J

    2013-08-01

    It has recently been found that lipid composition appears to have a major influence on the rate of lipase-induced degradation of lipid-based extended release drug delivery systems (microparticles, compressed implants and extrudated implants). Previously, we have found that during lipase incubation, depending on the lipid used, lipidic extrudates can lose their physical strength and collapse generating lipid particles in the μm-range. The aim of this study was to characterise the processes leading to collapse of solid lipid-based drug delivery systems during in vitro lipase incubation. Compressed lipid implants were used as model systems. Free fatty acids (FFA) generated in the incubation experiments were derivatised and subsequently analysed via reversed phase-HPLC in order to characterise the degradation behaviour of single lipid components (glyceryltrilaurate (D112), glyceryltrimyristate (D114), glyceryltripalmitate (D116) and glyceryltristearate (D118)) used for the preparation of compressed lipid implants. Further, Raman spectroscopy/microscopy, differential scanning calorimetry, scanning electron and light microscopy were used to investigate the physical and chemical changes in the implants upon lipase incubation. This study revealed that the lipid component D112 plays a major role in the degradation and erosion processes occurring during lipase incubation of lipid implants. The production of D112/lauric acid mixtures, with a melting point below human body temperature, leads to lipid matrices melting and losing their physical integrity.

  18. Third colloquium in biological sciences: Cellular signal transduction

    SciTech Connect

    Strand, F.L.

    1987-01-01

    This book contains over 100 papers. Some of the paper titles are: Characterization of Antibodies to DNA by Immunoadsorption on Cation-Complexed DNA; Simultaneous Evaluation of Radiochromatography Strips Using Gamma Camera Interfaced to a Computer; Simultaneous Quantification of Procine Myocardial Adenine Nucleotides and Creatine Phosphate by Ion-Pair Reverse-Phase High-Performance Liquid Chromatography; HPLC Analysis of Proteins from Alzheimer Paired Helical Filaments; and Internal Dosimetry Evaluations of Various Organs in Humans Using a Computerized Model.

  19. Mechanosensory calcium-selective cation channels in epidermal cells

    NASA Technical Reports Server (NTRS)

    Ding, J. P.; Pickard, B. G.

    1993-01-01

    This paper explores the properties and likely functions of an epidermal Ca(2+)-selective cation channel complex activated by tension. As many as eight or nine linked or linkable equivalent conductance units or co-channels can open together. Open time for co-channel quadruplets and quintuplets tends to be relatively long with millimolar Mg2+ (but not millimolar Ca2+) at the cytosolic face of excised plasma membrane. Sensitivity to tension is regulated by transmembrane voltage and temperature. Under some circumstances channel activity is sychronized in rhythmic pulses. Certain lanthanides and a cytoskeleton-disturbing herbicide that inhibit gravitropic reception act on the channel system at low concentrations. Specifically, ethyl-N-phenylcarbamate promotes tension-dependent activity at micromolar levels. With moderate suction, Gd3+ provided at about 0.5 micromole at the extracellular face of the membrane promotes for several seconds but may then become inhibitory. Provision at 1-2 micromoles promotes and subsequently inhibits more vigorously (often abruptly and totally), and at high levels inhibits immediately. La3+, a poor gravitropic inhibitor, acts similarly but much more gradually and only at much higher concentrations. These properties, particularly these susceptibilities to modulation, indicate that in vivo the mechanosensitive channel must be mechanosensory and mechanoregulatory. It could serve to transduce the shear forces generated in the integrated wall-membrane-cytoskeleton system during turgor changes and cell expansion as well as transducing the stresses induced by gravity, touch and flexure. In so far as such transduction is modulated by voltage and temperature, the channels would also be sensors for these modalities as long as the wall-membrane-cytoskeleton system experiences mechanical stress.

  20. Analysis of the gravitaxis signal transduction chain in Euglena gracilis

    NASA Astrophysics Data System (ADS)

    Nasir, Adeel

    Abstract Euglena gracilis is a photosynthetic, eukaryotic flagellate. It can adapt autotrophic and heterotrophic mode of growth and respond to different stimuli, this makes it an organism of choice for different research disciplines. It swims to reach a suitable niche by employing different stimuli such as oxygen, light, gravity and different chemicals. Among these stimuli light and gravity are the most important. Phototaxis (locomotion under light stimulus) and gravitaxis (locomotion under gravity stimulus) synergistically help cells to attain an optimal niche in the environment. However, in the complete absence of light or under scarcity of detectable light, cells can totally depend on gravity to find its swimming path. Therefore gravity has certain advantages over other stimuli.Unlike phototatic signal transduction chain of Euglena gracilis no clear primary gravity receptor has been identified in Euglena cells so far. However, there are some convincing evidence that TRP like channels act as a primary gravity receptor in Euglena gracilis.Use of different inhibitors gave rise to the involvement of protein kinase and calmodulin proteins in signal transduction chain of Euglena gracilis. Recently, specific calmodulin (Calmodulin 2) and protein kinase (PKA) have been identified as potential candidates of gravitactic signal transduction chain. Further characterization and investigation of these candidates was required. Therefore a combination of biochemical and genetic techniques was employed to localize proteins in cells and also to find interacting partners. For localization studies, specific antibodies were raised and characterized. Specificity of antibodies was validated by knockdown mutants, Invitro-translated proteins and heterologously expressed proteins. Cell fractionation studies, involving separation of the cell body and flagella for western blot analysis and confocal immunofluorescence studies were performed for subcellular localization. In order to find

  1. Sensory Transduction of the CO2 Response of Guard Cells

    SciTech Connect

    Dr. Eduardo Zeiger

    2003-06-30

    Stomata have a key role in the regulation of gas exchange and intercellular CO2 concentrations of leaves. Guard cells sense internal and external signals in the leaf environment and transduce these signals into osmoregulatory processes that control stomatal apertures. This research proposal addresses the characterization of the sensory transduction of the CO2 signal in guard cells. Recent studies have shown that in Vicia leaves kept at constant light and temperature in a growth chamber, changes in ambient CO2 concentrations cause large changes in guard cell zeaxanthin that are linear with CO2-dependent changes in stomatal apertures. Research proposed here will test the hypothesis that zeaxanthin function as a transducer of CO2 signals in guard cells. Three central aspects of this hypothesis will be investigated: CO2 sensing by the carboxylation reaction of Rubisco in the guard cell chloroplast, which would modulate zeaxanthin concentrations via changes in lumen pH; transduction of the CO2 signal by zeaxanthin via a transducing cascade that controls guard cell osmoregulation; and blue light dependence of the CO2 signal transduction by zeaxanthin, required for the formation of an isomeric form of zeaxanthin that is physiologically active as a transducer. The role of Rubisco in CO2 sensing will be investigated in experiments characterizing the stomatal response to CO2 in the Arabidopsis mutants R100 and rca-, which have reduced rates of Rubisco-dependent carboxylation. The role of zeaxanthin as a CO2 transducer will be studied in npq1, a zeaxanthin-less mutant. The blue light-dependence of CO2 sensing will be studied in experiments characterizing the stomatal response to CO2 under red light. Arabidopsis mutants will also be used in further studies of an acclimation of the stomatal response to CO2, and a possible role of the xanthophyll cycle of the guard cell chloroplast in acclimations of the stomatal response to CO2. Studies on the osmoregulatory role of sucrose in

  2. Mechanism of oligonucleotide release from cationic liposomes.

    PubMed Central

    Zelphati, O; Szoka, F C

    1996-01-01

    We propose a mechanism for oligonucleotide (ODN) release from cationic lipid complexes in cells that accounts for various observations on cationic lipid-nucleic acid-cell interactions. Fluorescent confocal microscopy of cells treated with rhodamine-labeled cationic liposome/ fluorescein-labeled ODN (F-ODN) complexes show the F-ODN separates from the lipid after internalization and enters the nucleus leaving the fluorescent lipid in cytoplasmic structures. ODN displacement from the complex was studied by fluorescent resonance energy transfer. Anionic liposome compositions (e.g., phosphatidylserine) that mimic the cytoplasmic facing monolayer of the cell membrane released ODN from the complex at about a 1:1 (-/+) charge ratio. Release was independent of ionic strength and pH. Physical separation of the F-ODN from monovalent and multivalent cationic lipids was confirmed by gel electrophoresis. Fluid but not solid phase anionic liposomes are required, whereas the physical state of the cationic lipids does not effect the release. Water soluble molecules with a high negative linear charge density, dextran sulfate, or heparin also release ODN. However, ATP, spermidine, spermine, tRNA, DNA, polyglutamic acid, polylysine, bovine serum albumin, or histone did not release ODN, even at 100-fold charge excess (-/+). Based upon these results, we propose that the complex, after internalization by endocytosis, induces flip-flop of anionic lipids from the cytoplasmic facing monolayer. Anionic lipids laterally diffuse into the complex and form a charged neutralized ion-pair with the cationic lipids. This leads to displacement of the ODN from the cationic lipid and its release into the cytoplasm. Images Fig. 1 Fig. 3 PMID:8876163

  3. Mechanistic Insights in Ethylene Perception and Signal Transduction1

    PubMed Central

    Ju, Chuanli; Chang, Caren

    2015-01-01

    The gaseous hormone ethylene profoundly affects plant growth, development, and stress responses. Ethylene perception occurs at the endoplasmic reticulum membrane, and signal transduction leads to a transcriptional cascade that initiates diverse responses, often in conjunction with other signals. Recent findings provide a more complete picture of the components and mechanisms in ethylene signaling, now rendering a more dynamic view of this conserved pathway. This includes newly identified protein-protein interactions at the endoplasmic reticulum membrane, as well as the major discoveries that the central regulator ETHYLENE INSENSITIVE2 (EIN2) is the long-sought phosphorylation substrate for the CONSTITUTIVE RESPONSE1 protein kinase, and that cleavage of EIN2 transmits the signal to the nucleus. In the nucleus, hundreds of potential gene targets of the EIN3 master transcription factor have been identified and found to be induced in transcriptional waves, and transcriptional coregulation has been shown to be a mechanism of ethylene cross talk. PMID:26246449

  4. Perspective: Adhesion Mediated Signal Transduction in Bacterial Pathogens.

    PubMed

    Moorthy, Sudha; Keklak, Julia; Klein, Eric A

    2016-01-01

    During the infection process, pathogenic bacteria undergo large-scale transcriptional changes to promote virulence and increase intrahost survival. While much of this reprogramming occurs in response to changes in chemical environment, such as nutrient availability and pH, there is increasing evidence that adhesion to host-tissue can also trigger signal transduction pathways resulting in differential gene expression. Determining the molecular mechanisms of adhesion-mediated signaling requires disentangling the contributions of chemical and mechanical stimuli. Here we highlight recent work demonstrating that surface attachment drives a transcriptional response in bacterial pathogens, including uropathogenic Escherichia coli (E. coli), and discuss the complexity of experimental design when dissecting the specific role of adhesion-mediated signaling during infection.

  5. Transduction of the gravity stimulus in the root statocyte.

    PubMed

    Perbal, G; Driss-Ecole, D

    1994-01-01

    The amyloplasts of root statocytes are considered to be the perceptors of gravity. However, their displacement and the starch they contain are not required for gravisensing. The mechanism of the transduction of gravistimulus remains therefore controversial. It is well known that the amplitude of the stimulus is dependent upon the intensity of the acceleration and the inclination of the root with respect to gravity. This strongly supports the hypothesis that the stimulus results in a mechanical effect (pressure or tension) on a cellular structure. Three cellular components are proposed as possible candidates for the role of transducer: the actin filaments, the endoplasmic reticulum and the plasma membrane with its ion channels. Recent results obtained in the frame of the IML 1 Mission of Spacelab show that the endoplasmic reticulum should rather be responsible for the termination of the stimulus. The contacts of amyloplasts with the distal ER could therefore be involved in the regulation of root growth. PMID:11537906

  6. Lentiviral vector production, titration, and transduction of primary neurons.

    PubMed

    Ding, Baojin; Kilpatrick, Daniel L

    2013-01-01

    Lentiviral vectors have become very useful tools for transgene delivery. Based on their ability to transduce both dividing and nondividing cells and to produce long-term transgene expression, lentiviruses have found numerous applications in the biomedical sciences, including developmental neuroscience. This protocol describes how to prepare lentiviral vectors by calcium phosphate transfection and to concentrate viral particles by ultracentrifugation. Functional vector titers can then be determined by methods such as fluorescence-activated cell sorting or immunostaining. Effective titers in the range of 10(8)-10(9) infectious units/ml can be routinely obtained using these protocols. Finally, we describe the infection of primary neuronal cultures with lentiviral vectors resulting in 85-90 % cell transduction using appropriate multiplicities of infection.

  7. Reactive oxygen species mediate insulin signal transduction in mouse hypothalamus.

    PubMed

    Onoue, Takeshi; Goto, Motomitsu; Tominaga, Takashi; Sugiyama, Mariko; Tsunekawa, Taku; Hagiwara, Daisuke; Banno, Ryoichi; Suga, Hidetaka; Sugimura, Yoshihisa; Arima, Hiroshi

    2016-04-21

    In the hypothalamus, several reports have implied that ROS mediate physiological effects of insulin. In this study, we investigated the mechanisms of insulin-induced ROS production and the effect of ROS on insulin signal transduction in mouse hypothalamic organotypic cultures. Insulin increased intracellular ROS, which were suppressed by NADPH oxidase inhibitor. H2O2 increased phospho-insulin receptor β (p-IRβ) and phospho-Akt (p-Akt) levels. Insulin-induced increases in p-IRβ and p-Akt levels were attenuated by ROS scavenger or NADPH oxidase inhibitor. Our data suggest that insulin-induced phosphorylation of IRβ and Akt is mediated via ROS which are predominantly produced by NADPH oxidase in mouse hypothalamus.

  8. A Model for Axon Guidance: Sensing, Transduction and Movement

    NASA Astrophysics Data System (ADS)

    Aletti, Giacomo; Causin, Paola; Naldi, Giovanni

    2008-07-01

    Axon guidance by graded diffusible ligands plays a crucial role in the developing nervous system. In this paper, we extend the mathematical description of the growth cone transduction cascade of [1] by adding a model of the gradient sensing process related to the theory of [2]. The resulting model is composed by a series of subsystems characterized by suitable input/output relations. The study of the transmission of the noise-to-signal ratio allows to predict the variability of the gradient assay as a function of experimental parameters as the ligand concentration, both in the single and in the multiple ligand tests. For this latter condition, we address the biologically relevant case of silencing in commissural axons. We also consider a phenomenological model which reproduces the results of the experiments of [3]. This simple model allows to test hypotheses on receptor functions and regulation in time.

  9. Melusin Promotes a Protective Signal Transduction Cascade in Stressed Hearts

    PubMed Central

    Sorge, Matteo; Brancaccio, Mara

    2016-01-01

    Melusin is a chaperone protein selectively expressed in heart and skeletal muscles. Melusin expression levels correlate with cardiac function in pre-clinical models and in human patients with aortic stenosis. Indeed, previous studies in several animal models indicated that Melusin plays a broad cardioprotective role in different pathological conditions. Chaperone proteins, besides playing a role in protein folding, are also able to facilitate supramolecular complex formation and conformational changes due to activation/deactivation of signaling molecules. This role sets chaperone proteins as crucial regulators of intracellular signal transduction pathways. In particular Melusin activates AKT and ERK1/2 signaling, protects cardiomyocytes from apoptosis and induces a compensatory hypertrophic response in several pathological conditions. Therefore, selective delivery of the Melusin gene in heart via cardiotropic adenoviral associated virus serotype 9 (AAV9), may represent a new promising gene-therapy approach for different cardiac pathologies. PMID:27672636

  10. Molecular Mechanisms of Two-Component Signal Transduction.

    PubMed

    Zschiedrich, Christopher P; Keidel, Victoria; Szurmant, Hendrik

    2016-09-25

    Two-component systems (TCS) comprising sensor histidine kinases and response regulator proteins are among the most important players in bacterial and archaeal signal transduction and also occur in reduced numbers in some eukaryotic organisms. Given their importance to cellular survival, virulence, and cellular development, these systems are among the most scrutinized bacterial proteins. In the recent years, a flurry of bioinformatics, genetic, biochemical, and structural studies have provided detailed insights into many molecular mechanisms that underlie the detection of signals and the generation of the appropriate response by TCS. Importantly, it has become clear that there is significant diversity in the mechanisms employed by individual systems. This review discusses the current knowledge on common themes and divergences from the paradigm of TCS signaling. An emphasis is on the information gained by a flurry of recent structural and bioinformatics studies.

  11. Simulation of signal transduction in model multiprotein systems

    NASA Astrophysics Data System (ADS)

    Su, Julius

    2009-03-01

    To simulate the dynamics of multiprotein machines, I have developed a method called multiconformer Brownian dynamics (mcBD). In this method, proteins rotate and translate via Brownian motion while their conformations are varied among a prestored set of structures on a simplified energy landscape, taking into account inter-protein interactions. As an example, I build a simple model of a G-protein coupled receptor/G-protein complex, and show that ligand binding causes conformational shifts, which induce GDP to leave, GTP to bind, and the complex to dissociate. The two proteins couple their fast fluctuations together into large-scale coordinated functional motions, resulting in signal transduction. I vary the shapes, electrostatics, and energy landscapes of the proteins independently and examine the impact this has on the system's function. In one result, increasing the binding between proteins improves the fidelity of communication, but at the expense of overall switching frequency.

  12. Perspective: Adhesion Mediated Signal Transduction in Bacterial Pathogens

    PubMed Central

    Moorthy, Sudha; Keklak, Julia; Klein, Eric A.

    2016-01-01

    During the infection process, pathogenic bacteria undergo large-scale transcriptional changes to promote virulence and increase intrahost survival. While much of this reprogramming occurs in response to changes in chemical environment, such as nutrient availability and pH, there is increasing evidence that adhesion to host-tissue can also trigger signal transduction pathways resulting in differential gene expression. Determining the molecular mechanisms of adhesion-mediated signaling requires disentangling the contributions of chemical and mechanical stimuli. Here we highlight recent work demonstrating that surface attachment drives a transcriptional response in bacterial pathogens, including uropathogenic Escherichia coli (E. coli), and discuss the complexity of experimental design when dissecting the specific role of adhesion-mediated signaling during infection. PMID:26901228

  13. Signal Transduction Model of Magnetic Sensing in Cryptochrome Mediated Photoreception

    NASA Astrophysics Data System (ADS)

    Todd, Phillise Tiffeny

    While migratory birds have long been known to use the Earth's magnetic field for navigation, the precise biophysical mechanism behind this magnetic sense remains unconfirmed. A leading theory of magnetoreception suggests a chemical compass model with a yet undetermined molecular reaction site and unknown magnetically sensitive reactants. The cryptochrome photoreceptor has emerged as a promising candidate site. This investigation numerically models the first order kinetics of cryptochrome mediated photoreception, in order to evaluate its ability to function as a magnetic sensor and transduce orientation information along a neural pathway. A signal-to-noise ratio is defined to quantify the threshold for the functioning of a cryptochrome-based chemical compass. The model suggests that a flavin-superoxide radical pair in cryptochrome functions as the chemical reactants for magnetoreception. Such a cryptochrome-based signal transduction model reasonably predicts the general light intensity and wavelength effects that have been experimentally observed in migratory birds.

  14. Signal Transduction and Intracellular Trafficking by the Interleukin 36 Receptor*

    PubMed Central

    Saha, Siddhartha S.; Singh, Divyendu; Raymond, Ernest L.; Ganesan, Rajkumar; Caviness, Gary; Grimaldi, Christine; Woska, Joseph R.; Mennerich, Detlev; Brown, Su-Ellen; Mbow, M. Lamine; Kao, C. Cheng

    2015-01-01

    Improper signaling of the IL-36 receptor (IL-36R), a member of the IL-1 receptor family, has been associated with various inflammation-associated diseases. However, the requirements for IL-36R signal transduction remain poorly characterized. This work seeks to define the requirements for IL-36R signaling and intracellular trafficking. In the absence of cognate agonists, IL-36R was endocytosed and recycled to the plasma membrane. In the presence of IL-36, IL-36R increased accumulation in LAMP1+ lysosomes. Endocytosis predominantly used a clathrin-mediated pathway, and the accumulation of the IL-36R in lysosomes did not result in increased receptor turnover. The ubiquitin-binding Tollip protein contributed to IL-36R signaling and increased the accumulation of both subunits of the IL-36R. PMID:26269592

  15. Interferons, Signal Transduction Pathways, and the Central Nervous System

    PubMed Central

    Nallar, Shreeram C.

    2014-01-01

    The interferon (IFN) family of cytokines participates in the development of innate and acquired immune defenses against various pathogens and pathogenic stimuli. Discovered originally as a proteinaceous substance secreted from virus-infected cells that afforded immunity to neighboring cells from virus infection, these cytokines are now implicated in various human pathologies, including control of tumor development, cell differentiation, and autoimmunity. It is now believed that the IFN system (IFN genes and the genes induced by them, and the factors that regulate these processes) is a generalized alarm of cellular stress, including DNA damage. IFNs exert both beneficial and deleterious effects on the central nervous system (CNS). Our knowledge of the IFN-regulated processes in the CNS is far from being clear. In this article, we reviewed the current understanding of IFN signal transduction pathways and gene products that might have potential relevance to diseases of the CNS. PMID:25084173

  16. Graviperception in ciliates: steps in the transduction chain.

    PubMed

    Hemmersbach, R; Krause, M; Bräucker, R; Ivanova, K

    2005-01-01

    Ciliates represent suitable model systems to study the mechanisms of graviperception and signal transduction as they show clear gravity-induced behavioural responses (gravitaxis and gravikinesis). The cytoplasm seems to act as a "statolith" stimulating mechanosensitive ion channels in the cell membrane. In order to test this hypothesis, electrophysiological studies with Stylonychia mytilus were performed, revealing the proposed changes (de- or hyperpolarization) depending on the cell's spatial orientation. The behaviour of Paramecium and Stylonychia was also analyzed during variable acceleration conditions of parabolic flights (5th German Parabolic Flight Campaign, 2003). The corresponding data confirm the relaxation of the graviresponses in microgravity as well as the existence of thresholds of graviresponses, which are found to be in the range of 0.4xg (gravikinesis) and 0.6xg (gravitaxis).

  17. Graviperception in ciliates: Steps in the transduction chain

    NASA Astrophysics Data System (ADS)

    Hemmersbach, R.; Krause, M.; Bräucker, R.; Ivanova, K.

    Ciliates represent suitable model systems to study the mechanisms of graviperception and signal transduction as they show clear gravity-induced behavioural responses (gravitaxis and gravikinesis). The cytoplasm seems to act as a "statolith" stimulating mechanosensitive ion channels in the cell membrane. In order to test this hypothesis, electrophysiological studies with Stylonychia mytilus were performed, revealing the proposed changes (de- or hyperpolarization) depending on the cell's spatial orientation. The behaviour of Paramecium and Stylonychia was also analyzed during variable acceleration conditions of parabolic flights (5th German Parabolic Flight Campaign, 2003). The corresponding data confirm the relaxation of the graviresponses in microgravity as well as the existence of thresholds of graviresponses, which are found to be in the range of 0.4× g (gravikinesis) and 0.6× g (gravitaxis).

  18. Piezoelectric Multilayer-Stacked Hybrid Actuation/Transduction System

    NASA Technical Reports Server (NTRS)

    Xu, Tian-Bing (Inventor); Jiang, Xiaoning (Inventor); Su, Ji (Inventor)

    2014-01-01

    A novel full piezoelectric multilayer stacked hybrid actuation/transduction system. The system demonstrates significantly-enhanced electromechanical performance by utilizing the cooperative contributions of the electromechanical responses of multilayer stacked negative and positive strain components. Both experimental and theoretical studies indicate that for this system, the displacement is over three times that of a same-sized conventional flextensional actuator/transducer. The system consists of at least 2 layers which include electromechanically active components. The layers are arranged such that when electric power is applied, one layer contracts in a transverse direction while the second layer expands in a transverse direction which is perpendicular to the transverse direction of the first layer. An alternate embodiment includes a third layer. In this embodiment, the outer two layers contract in parallel transverse directions while the middle layer expands in a transverse direction which is perpendicular to the transverse direction of the outer layers.

  19. Mechanistic Insights in Ethylene Perception and Signal Transduction.

    PubMed

    Ju, Chuanli; Chang, Caren

    2015-09-01

    The gaseous hormone ethylene profoundly affects plant growth, development, and stress responses. Ethylene perception occurs at the endoplasmic reticulum membrane, and signal transduction leads to a transcriptional cascade that initiates diverse responses, often in conjunction with other signals. Recent findings provide a more complete picture of the components and mechanisms in ethylene signaling, now rendering a more dynamic view of this conserved pathway. This includes newly identified protein-protein interactions at the endoplasmic reticulum membrane, as well as the major discoveries that the central regulator ETHYLENE INSENSITIVE2 (EIN2) is the long-sought phosphorylation substrate for the CONSTITUTIVE RESPONSE1 protein kinase, and that cleavage of EIN2 transmits the signal to the nucleus. In the nucleus, hundreds of potential gene targets of the EIN3 master transcription factor have been identified and found to be induced in transcriptional waves, and transcriptional coregulation has been shown to be a mechanism of ethylene cross talk.

  20. Transductive SVM for reducing the training effort in BCI

    NASA Astrophysics Data System (ADS)

    Liao, Xiang; Yao, Dezhong; Li, Chaoyi

    2007-09-01

    A brain-computer interface (BCI) provides a communication channel that translates human intention reflected by a brain signal such as electroencephalogram (EEG) into a control signal for an output device. In this work, the main concern is to reduce the training effort for BCI, which is often tedious and time consuming. Here we introduce a transductive support vector machines (TSVM) algorithm for the classification of EEG signals associated with mental tasks. TSVM possess the property of using both labeled and unlabeled data for reducing the calibration time in BCI and achieving good performance in classification accuracy. The advantages of the proposed method over the traditional supervised support vector machines (SVM) method are confirmed by about 2%-9% higher classification accuracies on a set of EEG recordings of three subjects from three-tasks-based mental imagery experiments. This work was supported by the National Natural Science Foundation of China under Grant 30525030 and 60571019, the 973 Project No. 2003CB716106.

  1. Engineering aspects of enzymatic signal transduction: photoreceptors in the retina.

    PubMed Central

    Detwiler, P B; Ramanathan, S; Sengupta, A; Shraiman, B I

    2000-01-01

    Identifying the basic module of enzymatic amplification as an irreversible cycle of messenger activation/deactivation by a "push-pull" pair of opposing enzymes, we analyze it in terms of gain, bandwidth, noise, and power consumption. The enzymatic signal transduction cascade is viewed as an information channel, the design of which is governed by the statistical properties of the input and the noise and dynamic range constraints of the output. With the example of vertebrate phototransduction cascade we demonstrate that all of the relevant engineering parameters are controlled by enzyme concentrations and, from functional considerations, derive bounds on the required protein numbers. Conversely, the ability of enzymatic networks to change their response characteristics by varying only the abundance of different enzymes illustrates how functional diversity may be built from nearly conserved molecular components. PMID:11106590

  2. Melusin Promotes a Protective Signal Transduction Cascade in Stressed Hearts

    PubMed Central

    Sorge, Matteo; Brancaccio, Mara

    2016-01-01

    Melusin is a chaperone protein selectively expressed in heart and skeletal muscles. Melusin expression levels correlate with cardiac function in pre-clinical models and in human patients with aortic stenosis. Indeed, previous studies in several animal models indicated that Melusin plays a broad cardioprotective role in different pathological conditions. Chaperone proteins, besides playing a role in protein folding, are also able to facilitate supramolecular complex formation and conformational changes due to activation/deactivation of signaling molecules. This role sets chaperone proteins as crucial regulators of intracellular signal transduction pathways. In particular Melusin activates AKT and ERK1/2 signaling, protects cardiomyocytes from apoptosis and induces a compensatory hypertrophic response in several pathological conditions. Therefore, selective delivery of the Melusin gene in heart via cardiotropic adenoviral associated virus serotype 9 (AAV9), may represent a new promising gene-therapy approach for different cardiac pathologies.

  3. The mechanism of signal transduction by two-component systems.

    PubMed

    Casino, Patricia; Rubio, Vicente; Marina, Alberto

    2010-12-01

    Two-component systems, composed of a homodimeric histidine kinase (HK) and a response regulator (RR), are major signal transduction devices in bacteria. Typically the signal triggers HK autophosphorylation at one His residue, followed by phosphoryl transfer from the phospho-His to an Asp residue in the RR. Signal extinction frequently involves phospho-RR dephosphorylation by a phosphatase activity of the HK. Our understanding of these reactions and of the determinants of partner specificity among HK-RR couples has been greatly increased by recent crystal structures and biochemical experiments on HK-RR complexes. Cis-autophosphorylation (one subunit phosphorylates itself) occurs in some HKs while trans-autophosphorylation takes place in others. We review and integrate this new information, discuss the mechanism of the three reactions and propose a model for transmembrane signaling by these systems.

  4. Molecular immunology--gene regulation and signal transduction.

    PubMed

    Hopkins, John

    2002-09-10

    Research on 'molecular immunology-gene regulation and signal transduction' in veterinary species is relatively new. The reason for its novelty is that until recently there have been very few tools with which we can work. Over the last 10 years the veterinary immunology community has succeeded in generating panels of defined monoclonal antibodies (mAb) and cloned genes that has enabled such work to be started. More recently, quantitative, high-resolution analytical tools for veterinary species have begun to be developed; some of these are specific for veterinary species and others have been adapted from human or rodent systems. Of the species-specific tools that have recently been developed perhaps the most widely used are the immunoassays for cytokines, RNAase protection assays (RPAs) and in the near future oligonucleotide and EST-based microarrays. This presentation will describe some of these assays and discuss their relative advantages and disadvantages.

  5. Molecular biology of thermosensory transduction in C. elegans.

    PubMed

    Aoki, Ichiro; Mori, Ikue

    2015-10-01

    As the environmental temperature prominently influences diverse biological aspects of the animals, thermosensation and the subsequent information processing in the nervous system has attracted much attention in biology. Thermotaxis in the nematode Caenorhabditis elegans is an ideal behavioral paradigm by which to address the molecular mechanism underlying thermosensory transduction. Molecular genetic analysis in combination with other physiological and behavioral studies revealed that sensation of ambient temperature is mediated mainly by cyclic guanosine monophosphate (cGMP) signaling in thermosensory neurons. The information of the previously perceived temperature is also stored within the thermosensory neurons, and the consequence of the comparison between the past and the present temperature is conveyed to the downstream interneurons to further regulate the motor-circuits that encode the locomotion.

  6. Monocyte Signal Transduction Receptors in Active and Latent Tuberculosis

    PubMed Central

    Druszczynska, Magdalena; Wlodarczyk, Marcin; Janiszewska-Drobinska, Beata; Kielnierowski, Grzegorz; Zawadzka, Joanna; Kowalewicz-Kulbat, Magdalena; Fol, Marek; Szpakowski, Piotr; Rudnicka, Karolina; Chmiela, Magdalena; Rudnicka, Wieslawa

    2013-01-01

    The mechanisms that promote either resistance or susceptibility to TB disease remain insufficiently understood. Our aim was to compare the expression of cell signaling transduction receptors, CD14, TLR2, CD206, and β2 integrin LFA-1 on monocytes from patients with active TB or nonmycobacterial lung disease and healthy individuals with M.tb latency and uninfected controls to explain the background of the differences between clinical and subclinical forms of M.tb infection. A simultaneous increase in the expression of the membrane bound mCD14 receptor and LFA-1 integrin in patients with active TB may be considered a prodrome of breaking immune control by M.tb bacilli in subjects with the latent TB and absence of clinical symptoms. PMID:23401703

  7. Interferons, signal transduction pathways, and the central nervous system.

    PubMed

    Nallar, Shreeram C; Kalvakolanu, Dhan V

    2014-08-01

    The interferon (IFN) family of cytokines participates in the development of innate and acquired immune defenses against various pathogens and pathogenic stimuli. Discovered originally as a proteinaceous substance secreted from virus-infected cells that afforded immunity to neighboring cells from virus infection, these cytokines are now implicated in various human pathologies, including control of tumor development, cell differentiation, and autoimmunity. It is now believed that the IFN system (IFN genes and the genes induced by them, and the factors that regulate these processes) is a generalized alarm of cellular stress, including DNA damage. IFNs exert both beneficial and deleterious effects on the central nervous system (CNS). Our knowledge of the IFN-regulated processes in the CNS is far from being clear. In this article, we reviewed the current understanding of IFN signal transduction pathways and gene products that might have potential relevance to diseases of the CNS.

  8. Melusin Promotes a Protective Signal Transduction Cascade in Stressed Hearts.

    PubMed

    Sorge, Matteo; Brancaccio, Mara

    2016-01-01

    Melusin is a chaperone protein selectively expressed in heart and skeletal muscles. Melusin expression levels correlate with cardiac function in pre-clinical models and in human patients with aortic stenosis. Indeed, previous studies in several animal models indicated that Melusin plays a broad cardioprotective role in different pathological conditions. Chaperone proteins, besides playing a role in protein folding, are also able to facilitate supramolecular complex formation and conformational changes due to activation/deactivation of signaling molecules. This role sets chaperone proteins as crucial regulators of intracellular signal transduction pathways. In particular Melusin activates AKT and ERK1/2 signaling, protects cardiomyocytes from apoptosis and induces a compensatory hypertrophic response in several pathological conditions. Therefore, selective delivery of the Melusin gene in heart via cardiotropic adenoviral associated virus serotype 9 (AAV9), may represent a new promising gene-therapy approach for different cardiac pathologies. PMID:27672636

  9. Transductive multi-view zero-shot learning.

    PubMed

    Fu, Yanwei; Hospedales, Timothy M; Xiang, Tao; Gong, Shaogang

    2015-11-01

    Most existing zero-shot learning approaches exploit transfer learning via an intermediate semantic representation shared between an annotated auxiliary dataset and a target dataset with different classes and no annotation. A projection from a low-level feature space to the semantic representation space is learned from the auxiliary dataset and applied without adaptation to the target dataset. In this paper we identify two inherent limitations with these approaches. First, due to having disjoint and potentially unrelated classes, the projection functions learned from the auxiliary dataset/domain are biased when applied directly to the target dataset/domain. We call this problem the projection domain shift problem and propose a novel framework, transductive multi-view embedding, to solve it. The second limitation is the prototype sparsity problem which refers to the fact that for each target class, only a single prototype is available for zero-shot learning given a semantic representation. To overcome this problem, a novel heterogeneous multi-view hypergraph label propagation method is formulated for zero-shot learning in the transductive embedding space. It effectively exploits the complementary information offered by different semantic representations and takes advantage of the manifold structures of multiple representation spaces in a coherent manner. We demonstrate through extensive experiments that the proposed approach (1) rectifies the projection shift between the auxiliary and target domains, (2) exploits the complementarity of multiple semantic representations, (3) significantly outperforms existing methods for both zero-shot and N-shot recognition on three image and video benchmark datasets, and (4) enables novel cross-view annotation tasks.

  10. BRET biosensors to study GPCR biology, pharmacology, and signal transduction.

    PubMed

    Salahpour, Ali; Espinoza, Stefano; Masri, Bernard; Lam, Vincent; Barak, Larry S; Gainetdinov, Raul R

    2012-01-01

    Bioluminescence resonance energy transfer (BRET)-based biosensors have been extensively used over the last decade to study protein-protein interactions and intracellular signal transduction in living cells. In this review, we discuss the various BRET biosensors that have been developed to investigate biology, pharmacology, and signaling of G protein-coupled receptors (GPCRs). GPCRs form two distinct types of multiprotein signal transduction complexes based upon their inclusion of G proteins or β-arrestins that can be differentially affected by drugs that exhibit functional selectivity toward G protein or β-arrestin signaling. BRET has been especially adept at illuminating the dynamics of protein-protein interactions between receptors, G proteins, β-arrestins, and their many binding partners in living cells; as well as measuring the formation and accumulation of second messengers following receptor activation. Specifically, we discuss in detail the application of BRET to study dopamine and trace amine receptors signaling, presenting examples of an exchange protein activated by cAMP biosensor to measure cAMP, β-arrestin biosensors to determine β-arrestin recruitment to the receptor, and dopamine D2 receptor and trace amine-associated receptor 1 biosensors to investigate heterodimerization between them. As the biochemical spectrum of BRET biosensors expands, the number of signaling pathways that can be measured will concomitantly increase. This will be particularly useful for the evaluation of functional selectivity in which the real-time BRET capability to measure distinct signaling modalities will dramatically shorten the time to characterize new generation of biased drugs. These emerging approaches will further expand the growing application of BRET in the screening for novel pharmacologically active compounds.

  11. Gene Expressions for Signal Transduction under Acidic Conditions

    PubMed Central

    Fukamachi, Toshihiko; Ikeda, Syunsuke; Wang, Xin; Saito, Hiromi; Tagawa, Masatoshi; Kobayashi, Hiroshi

    2013-01-01

    Although it is now well known that some diseased areas, such as cancer nests, inflammation loci, and infarction areas, are acidified, little is known about cellular signal transduction, gene expression, and cellular functions under acidic conditions. Our group showed that different signal proteins were activated under acidic conditions compared with those observed in a typical medium of around pH 7.4 that has been used until now. Investigations of gene expression under acidic conditions may be crucial to our understanding of signal transduction in acidic diseased areas. In this study, we investigated gene expression in mesothelioma cells cultured at an acidic pH using a DNA microarray technique. After 24 h culture at pH 6.7, expressions of 379 genes were increased more than twofold compared with those in cells cultured at pH 7.5. Genes encoding receptors, signal proteins including transcription factors, and cytokines including growth factors numbered 35, 32, and 17 among the 379 genes, respectively. Since the functions of 78 genes are unknown, it can be argued that cells may have other genes for signaling under acidic conditions. The expressions of 37 of the 379 genes were observed to increase after as little as 2 h. After 24 h culture at pH 6.7, expressions of 412 genes were repressed more than twofold compared with those in cells cultured at pH 7.5, and the 412 genes contained 35, 76, and 7 genes encoding receptors, signal proteins including transcription factors, and cytokines including growth factors, respectively. These results suggest that the signal pathways in acidic diseased areas are different, at least in part, from those examined with cells cultured at a pH of around 7.4. PMID:24705103

  12. Mechanical signal transduction in skeletal muscle growth and adaptation.

    PubMed

    Tidball, James G

    2005-05-01

    The adaptability of skeletal muscle to changes in the mechanical environment has been well characterized at the tissue and system levels, but the mechanisms through which mechanical signals are transduced to chemical signals that influence muscle growth and metabolism remain largely unidentified. However, several findings have suggested that mechanical signal transduction in muscle may occur through signaling pathways that are shared with insulin-like growth factor (IGF)-I. The involvement of IGF-I-mediated signaling for mechanical signal transduction in muscle was originally suggested by the observations that muscle releases IGF-I on mechanical stimulation, that IGF-I is a potent agent for promoting muscle growth and affecting phenotype, and that IGF-I can function as an autocrine hormone in muscle. Accumulating evidence shows that at least two signaling pathways downstream of IGF-I binding can influence muscle growth and adaptation. Signaling via the calcineurin/nuclear factor of activated T-cell pathway has been shown to have a powerful influence on promoting the slow/type I phenotype in muscle but can also increase muscle mass. Neural stimulation of muscle can activate this pathway, although whether neural activation of the pathway can occur independent of mechanical activation or independent of IGF-I-mediated signaling remains to be explored. Signaling via the Akt/mammalian target of rapamycin pathway can also increase muscle growth, and recent findings show that activation of this pathway can occur as a response to mechanical stimulation applied directly to muscle cells, independent of signals derived from other cells. In addition, mechanical activation of mammalian target of rapamycin, Akt, and other downstream signals is apparently independent of autocrine factors, which suggests that activation of the mechanical pathway occurs independent of muscle-mediated IGF-I release.

  13. Aptamer modification improves the adenoviral transduction of malignant glioma cells.

    PubMed

    Chen, Hao; Zheng, Xiaojing; Di, BingYan; Wang, Dongyang; Zhang, Yaling; Xia, Haibin; Mao, Qinwen

    2013-12-01

    Adenovirus has shown increasing promise in the gene-viral therapy for glioblastoma, a treatment strategy that relies on the delivery of viruses or transgenes into tumor cells. However, targeting of adenovirus to human glioblastoma remains a challenge due to the low expression level of coxsackie and adenovirus receptor (CAR) in glioma cells. Aptamers are small and highly structured single-stranded oligonucleotides that bind at high affinity to a target molecule, and are good candidates for targeted imaging and therapy. In this study, to construct an aptamer-modified Ad5, we first genetically modified the HVR5 of Ad hexon by biotin acceptor peptide (BAP), which would be metabolically biotinylated during production in HEK293 cells, and then attached the biotin labeled aptamer to the modified Ad through avidin–biotin binding. The aptamers used in this study includes AS1411 and GBI-10. The former is a DNA aptamer that can bind to nucleolin, a nuclear matrix protein found on the surface of cancer cells. The latter is a DNA aptamer that can recognize the extracellular matrix protein tenascin-C on the surface of human glioblastoma cells. To examine if aptamer-modification of the hexon protein could improve the adenoviral transduction efficiency, a glioblastoma cell line, U251, was transduced with aptamer-modified Ads. The transduction efficiency of AS1411- or GBI-10-modified Ad was approximately 4.1-fold or 5.2-fold higher than that of the control. The data indicated that aptamer modified adenovirus would be a useful tool for cancer gene therapy.

  14. Influence of Unweighting on Insulin Signal Transduction in Muscle

    NASA Technical Reports Server (NTRS)

    Tischler, Marc E.

    2002-01-01

    Unweighting of the juvenile soleus muscle is characterized by an increased binding capacity for insulin relative to muscle mass due to sparing of the receptors during atrophy. Although carbohydrate metabolism and protein degradation in the unweighted muscle develop increased sensitivity to insulin in vivo, protein synthesis in vivo and system A amino acid transport in vitro do not appear to develop such an enhanced response. The long-term goal is to identify the precise nature of this apparent resistance in the insulin signal transduction pathway and to consider how reduced weight-bearing may elicit this effect, by evaluating specific components of the insulin signalling pathway. Because the insulin-signalling pathway has components in common with the signal transduction pathway for insulin-like growth factor (IGF-1) and potentially other growth factors, the study could have important implications in the role of weight-bearing function on muscle growth and development. Since the insulin signalling pathway diverges following activation of insulin receptor tyrosine kinase, the immediate specific aims will be to study the receptor tyrosine kinase (IRTK) and those branches, which lead to phosphorylation of insulin receptor substrate-1 (IRS-1) and of Shc protein. To achieve these broader objectives, we will test in situ, by intramuscular injection, the responses of glucose transport, system A amino acid transport and protein synthesis to insulin analogues for which the receptor has either a weaker or much stronger binding affinity compared to insulin. Studies will include: (1) estimation of the ED(sub 50) for each analogue for these three processes; (2) the effect of duration (one to four days) of unweighting on the response of each process to all analogues tested; (3) the effect of unweighting and the analogues on IRTK activity; and (4) the comparative effects of unweighting and analogue binding on the tyrosine phosphorylation of IRTK, IRS-1, and Shc protein.

  15. Transductive multi-view zero-shot learning.

    PubMed

    Fu, Yanwei; Hospedales, Timothy M; Xiang, Tao; Gong, Shaogang

    2015-11-01

    Most existing zero-shot learning approaches exploit transfer learning via an intermediate semantic representation shared between an annotated auxiliary dataset and a target dataset with different classes and no annotation. A projection from a low-level feature space to the semantic representation space is learned from the auxiliary dataset and applied without adaptation to the target dataset. In this paper we identify two inherent limitations with these approaches. First, due to having disjoint and potentially unrelated classes, the projection functions learned from the auxiliary dataset/domain are biased when applied directly to the target dataset/domain. We call this problem the projection domain shift problem and propose a novel framework, transductive multi-view embedding, to solve it. The second limitation is the prototype sparsity problem which refers to the fact that for each target class, only a single prototype is available for zero-shot learning given a semantic representation. To overcome this problem, a novel heterogeneous multi-view hypergraph label propagation method is formulated for zero-shot learning in the transductive embedding space. It effectively exploits the complementary information offered by different semantic representations and takes advantage of the manifold structures of multiple representation spaces in a coherent manner. We demonstrate through extensive experiments that the proposed approach (1) rectifies the projection shift between the auxiliary and target domains, (2) exploits the complementarity of multiple semantic representations, (3) significantly outperforms existing methods for both zero-shot and N-shot recognition on three image and video benchmark datasets, and (4) enables novel cross-view annotation tasks. PMID:26440271

  16. Protein Phylogenetic Analysis of Ca2+/cation Antiporters and Insights into their Evolution in Plants

    PubMed Central

    Emery, Laura; Whelan, Simon; Hirschi, Kendal D.; Pittman, Jon K.

    2012-01-01

    Cation transport is a critical process in all organisms and is essential for mineral nutrition, ion stress tolerance, and signal transduction. Transporters that are members of the Ca2+/cation antiporter (CaCA) superfamily are involved in the transport of Ca2+ and/or other cations using the counter exchange of another ion such as H+ or Na+. The CaCA superfamily has been previously divided into five transporter families: the YRBG, Na+/Ca2+ exchanger (NCX), Na+/Ca2+, K+ exchanger (NCKX), H+/cation exchanger (CAX), and cation/Ca2+ exchanger (CCX) families, which include the well-characterized NCX and CAX transporters. To examine the evolution of CaCA transporters within higher plants and the green plant lineage, CaCA genes were identified from the genomes of sequenced flowering plants, a bryophyte, lycophyte, and freshwater and marine algae, and compared with those from non-plant species. We found evidence of the expansion and increased diversity of flowering plant genes within the CAX and CCX families. Genes related to the NCX family are present in land plant though they encode distinct MHX homologs which probably have an altered transport function. In contrast, the NCX and NCKX genes which are absent in land plants have been retained in many species of algae, especially the marine algae, indicating that these organisms may share “animal-like” characteristics of Ca2+ homeostasis and signaling. A group of genes encoding novel CAX-like proteins containing an EF-hand domain were identified from plants and selected algae but appeared to be lacking in any other species. Lack of functional data for most of the CaCA proteins make it impossible to reliably predict substrate specificity and function for many of the groups or individual proteins. The abundance and diversity of CaCA genes throughout all branches of life indicates the importance of this class of cation transporter, and that many transporters with novel functions are waiting to be discovered. PMID:22645563

  17. The effect of multivalent cations and Tau on paclitaxel-stabilized microtubule assembly, disassembly, and structure.

    PubMed

    Safinya, Cyrus R; Chung, Peter J; Song, Chaeyeon; Li, Youli; Ewert, Kai K; Choi, Myung Chul

    2016-06-01

    In this review we describe recent studies directed at understanding the formation of novel nanoscale assemblies in biological materials systems. In particular, we focus on the effects of multivalent cations, and separately, of microtubule-associated protein (MAP) Tau, on microtubule (MT) ordering (bundling), MT disassembly, and MT structure. Counter-ion directed bundling of paclitaxel-stabilized MTs is a model electrostatic system, which parallels efforts to understand MT bundling by intrinsically disordered proteins (typically biological polyampholytes) expressed in neurons. We describe studies, which reveal an unexpected transition from tightly spaced MT bundles to loose bundles consisting of strings of MTs as the valence of the cationic counter-ion decreases from Z=3 to Z=2. This transition is not predicted by any current theories of polyelectrolytes. Notably, studies of a larger series of divalent counter-ions reveal strong ion specific effects. Divalent counter-ions may either bundle or depolymerize paclitaxel-stabilized MTs. The ion concentration required for depolymerization decreases with increasing atomic number. In a more biologically related system we review synchrotron small angle x-ray scattering (SAXS) studies on the effect of the Tau on the structure of paclitaxel-stabilized MTs. The electrostatic binding of MAP Tau isoforms leads to an increase in the average radius of microtubules with increasing Tau coverage (i.e. a re-distribution of protofilament numbers in MTs). Finally, inspired by MTs as model nanotubes, we briefly describe other more robust lipid-based cylindrical nanostructures, which may have technological applications, for example, in drug encapsulation and delivery. PMID:26684364

  18. The effect of multivalent cations and Tau on paclitaxel-stabilized microtubule assembly, disassembly, and structure.

    PubMed

    Safinya, Cyrus R; Chung, Peter J; Song, Chaeyeon; Li, Youli; Ewert, Kai K; Choi, Myung Chul

    2016-06-01

    In this review we describe recent studies directed at understanding the formation of novel nanoscale assemblies in biological materials systems. In particular, we focus on the effects of multivalent cations, and separately, of microtubule-associated protein (MAP) Tau, on microtubule (MT) ordering (bundling), MT disassembly, and MT structure. Counter-ion directed bundling of paclitaxel-stabilized MTs is a model electrostatic system, which parallels efforts to understand MT bundling by intrinsically disordered proteins (typically biological polyampholytes) expressed in neurons. We describe studies, which reveal an unexpected transition from tightly spaced MT bundles to loose bundles consisting of strings of MTs as the valence of the cationic counter-ion decreases from Z=3 to Z=2. This transition is not predicted by any current theories of polyelectrolytes. Notably, studies of a larger series of divalent counter-ions reveal strong ion specific effects. Divalent counter-ions may either bundle or depolymerize paclitaxel-stabilized MTs. The ion concentration required for depolymerization decreases with increasing atomic number. In a more biologically related system we review synchrotron small angle x-ray scattering (SAXS) studies on the effect of the Tau on the structure of paclitaxel-stabilized MTs. The electrostatic binding of MAP Tau isoforms leads to an increase in the average radius of microtubules with increasing Tau coverage (i.e. a re-distribution of protofilament numbers in MTs). Finally, inspired by MTs as model nanotubes, we briefly describe other more robust lipid-based cylindrical nanostructures, which may have technological applications, for example, in drug encapsulation and delivery.

  19. Innate cation sensitivity in a semiconducting polymer.

    PubMed

    Althagafi, Talal M; Algarni, Saud A; Grell, Martin

    2016-09-01

    Water-gated organic thin film transistors (OTFTs) using the hole transporting semiconducting polymer, poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT), show an innate response of their threshold voltage to the addition of divalent metal cations to the gating water, without deliberately introducing an ion-sensitive component. A similar threshold response is shown for several divalent cations, but is absent for monovalent cations. Response is absent for transistors using the inorganic semiconductor ZnO, or the similar organic semiconductor poly(3-hexylthiophene) (rrP3HT), instead of PBTTT. We assign innate cation sensitivity to residues of the organometallic Pd(0) complex used as catalyst in PBTTT synthesis which bears strong resemblance to typical metal chelating agents. Organometallic Pd(0) residues are absent from ZnO, and also from rrP3HT which is polymerised with a different type of catalyst. However, when Pd(0) complex is deliberately added to rrP3HT casting solutions, resulting OTFTs also display threshold response to a divalent cation. PMID:27343580

  20. Membrane penetrating peptides greatly enhance baculovirus transduction efficiency into mammalian cells

    SciTech Connect

    Chen, Hong-Zhang; Wu, Carol P.; Chao, Yu-Chan; Liu, Catherine Yen-Yen

    2011-02-11

    Research highlights: {yields} Ligation of CTP with GP64 enhances baculovirus transduction into mammalian cells. {yields} Fusion of PTD with VP39 enhances baculovirus transduction into mammalian cells. {yields} CTP and PTD-carrying viruses improve the transduction of co-transduced baculoviruses. {yields} Virus entry and gene expression can be separate events in different cell types. -- Abstract: The baculovirus group of insect viruses is widely used for foreign gene introduction into mammalian cells for gene expression and protein production; however, the efficiency of baculovirus entry into mammalian cells is in general still low. In this study, two recombinant baculoviruses were engineered and their ability to improve viral entry was examined: (1) cytoplasmic transduction peptide (CTP) was fused with baculovirus envelope protein, GP64, to produce a cytoplasmic membrane penetrating baculovirus (vE-CTP); and (2) the protein transduction domain (PTD) of HIV TAT protein was fused with the baculovirus capsid protein VP39 to form a nuclear membrane penetrating baculovirus (vE-PTD). Transduction experiments showed that both viruses had better transduction efficiency than vE, a control virus that only expresses EGFP in mammalian cells. Interestingly, vE-CTP and vE-PTD were also able to improve the transduction efficiency of a co-transduced baculovirus, resulting in higher levels of gene expression. Our results have described new routes to further enhance the development of baculovirus as a tool for gene delivery into mammalian cells.

  1. Generalized transduction of serotype 1/2 and serotype 4b strains of Listeria monocytogenes.

    PubMed

    Hodgson, D A

    2000-01-01

    This is the first report of generalized transduction in the gram-positive, food-borne pathogen Listeria monocytogenes. Bacteriophages were isolated from the environment and from lysogens, or were obtained from other laboratories. Of the 59 bacteriophages tested, 34 proved to be capable of transduction. We exploited the ability of L. monocytogenes to grow at room temperature and isolated bacteriophages that were incapable of growth at 37 degrees C. Transductions at this temperature therefore eliminated transductant killing and lysogeny, as did inclusion of citrate and the use of a low multiplicity of infection. Transducing bacteriophages were found for each of the well-characterized L. monocytogenes strains: EGD, 10403, Mack (serotype1/2a), L028 (serotype 1/2c), Scott A (serotype 4b) and strains from the Jalisco and Halifax, Nova Scotia outbreaks (serotype 4b). P35 (phiLMUP35) is a particularly useful generalized transducing bacteriophage with a wide host range (75% of all serotype 1/2 strains tested). Its disadvantages are that it is small and transduction is relatively infrequent. U153(phiCU-SI153/95) is larger than P35 and transduction frequency increased 100-fold, but it has a very narrow host range. We demonstrated interstrain transduction and used transduction to test linkage between transposon insertions and mutant phenotypes in a variety of strains.

  2. Novel lipid-based formulations enhancing the in vitro dissolution and permeability characteristics of a poorly water-soluble model drug, piroxicam.

    PubMed

    Prabhu, Sunil; Ortega, Maru; Ma, Chan

    2005-09-14

    Lipid-based delivery systems are becoming increasingly popular as carriers of drugs due to their ability to overcome barriers to oral absorption. The purpose of this study was to prepare novel lipid-based formulations of a model drug, piroxicam (PXCM), a poorly water-soluble non-steroidal anti-inflammatory drug (NSAID) using 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) phospholipid alone, and in combination with polyethylene glycol (PEG 4600). Lipid-based drug delivery systems were prepared using conventional methods of preparation and the following aspects were evaluated (1) in vitro dissolution behavior, (2) absorption via Caco-2 cell monolayers and (3) stability of formulations over a 12-month period. In addition, physical characterization studies using differential scanning calorimetry (DSC) were also performed. Formulations of PXCM were prepared using DMPC in the following combinations (A) 1:1 and (B) 2:1 and a mixture of DMPC and PEG 4600 (C) 2:1:1, respectively. Dissolution studies conducted in phosphate buffered saline (PBS, pH 7.4, 37+/-0.5 degrees C) using the USP type II (paddle) dissolution apparatus showed an increase in dissolution rate and extent of the PXCM from all solid dispersion formulations when compared to the control. As such, the rate of drug release was observed to be fastest with formulation (C) showing the greatest increase of over two-fold compared to the control. Release of PXCM from formulations (A) and (B) was intermediate with the latter showing superior dissolution behavior despite containing lower amounts of the carrier lipid than the former. This observation indicates a possible existence of threshold levels for phospholipids carriers beyond which dissolution could be adversely affected. DSC studies further confirmed the dissolution behavior of these formulations demonstrating different levels of amorphous to crystalline nature. Results of HPLC analysis from Caco-2 cell culture studies showed increase in transport of

  3. Intragenus generalized transduction in Staphylococcus spp. by a novel giant phage.

    PubMed

    Uchiyama, Jumpei; Takemura-Uchiyama, Iyo; Sakaguchi, Yoshihiko; Gamoh, Keiji; Kato, Shin-ichiro; Daibata, Masanori; Ujihara, Takako; Misawa, Naoaki; Matsuzaki, Shigenobu

    2014-09-01

    Bacteriophage (phage)-mediated generalized transduction is expected to contribute to the emergence of drug-resistant staphylococcal clones in various environments. In this study, novel phage S6 was isolated from sewage and used to test generalized transduction in human- and animal-derived staphylococci. Phage S6 was a novel type of giant myophage, which possessed a DNA genome that contained uracil instead of thymine, and it could infect all of the tested staphylococcal species. The phage S6 appeared to be similar to the transducing phage PBS1, which infects Bacillus spp. Moreover, phage S6 facilitated the transduction of a plasmid in Staphylococcus aureus and from S. aureus to non-aureus staphylococcal species, as well as vice versa. Transduction of methicillin resistance also occurred in S. aureus. This is the first report of successful intragenus generalized transduction among staphylococci.

  4. Cationically polymerizable monomers derived from renewable sources

    SciTech Connect

    Crivello, J.V.

    1991-10-01

    The objective of this project is to make use of products obtained from renewable plant sources as monomers for the direct production of polymers which can be used for a wide range of plastic applications. In this report is described progress in the synthesis and polymerization of cationically polymerizable monomers and oligomers derived from botanical oils, terpenes, natural rubber, and lignin. Nine different botanical oils were obtained from various sources, characterized and then epoxidized. Their photopolymerization was carried out using cationic photoinitiators and the mechanical properties of the resulting polymers characterized. Preliminary biodegradation studies are being conducted on the photopolymerized films from several of these oils. Limonene was cationically polymerized to give dimers and the dimers epoxidized to yield highly reactive monomers suitable for coatings, inks and adhesives. The direct phase transfer epoxidation of squalene and natural rubber was carried out. The modified rubbers undergo facile photocrosslinking in the presence of onium salts to give crosslinked elastomers. 12 refs., 3 figs., 10 tabs.

  5. Forging Colloidal Nanostructures via Cation Exchange Reactions

    PubMed Central

    2016-01-01

    Among the various postsynthesis treatments of colloidal nanocrystals that have been developed to date, transformations by cation exchange have recently emerged as an extremely versatile tool that has given access to a wide variety of materials and nanostructures. One notable example in this direction is represented by partial cation exchange, by which preformed nanocrystals can be either transformed to alloy nanocrystals or to various types of nanoheterostructures possessing core/shell, segmented, or striped architectures. In this review, we provide an up to date overview of the complex colloidal nanostructures that could be prepared so far by cation exchange. At the same time, the review gives an account of the fundamental thermodynamic and kinetic parameters governing these types of reactions, as they are currently understood, and outlines the main open issues and possible future developments in the field. PMID:26891471

  6. Electromers of the benzene dimer radical cation.

    PubMed

    Błoch-Mechkour, Anna; Bally, Thomas

    2015-04-28

    The well-studied benzene dimer radical cation, which is prototypical for this class of species, has been reinvestigated computationally. Thereby it turned out that both the σ-hemibonded and the half-shifted sandwich structures of the benzene dimer cation, which had been independently proposed, represent stationary points on the B2PLYP-D potential energy surfaces. However, these structures belong to distinct electronic states, both of which are associated with potential surfaces that are very flat with regard to rotation of the two benzene rings in an opposite sense relative to each other. The surfaces of these two "electromers" of the benzene dimer cation are separated by only 3-4 kcal mol(-1) and do not intersect along the rotation coordinate, which represents a rather unique electronic structure situation. When moving on either of the two surfaces the title complex is an extremely fluxional species, in spite of its being bound by over 20 kcal mol(-1).

  7. Generalized transduction: new aspects of the events in the water column

    NASA Astrophysics Data System (ADS)

    Velimirov, B.; Chiura, H. X.; Kogure, K.

    2003-04-01

    Virus mediated transfer of genetic elements among bacteria in nature has become a major research topic in the last decade. Along with conjugation and transformation, transduction is a well-known mechanism resulting in horizontal gene transfer in procaryotic organisms. In the case of generalized transduction, all regions of the procaryotic chromosome or other genetic elements in the donor cell are transferred with nearly the same frequency to the recipient. The injection of this DNA induces the generation of stable transductants. Both virulent and temperate phages have the capability to induce general transduction.Within the frame of a study on intergeneric phage-mediated gene transfer between marine bacteria and enteric bacteria, namely an auxotrophic mutant of Escherichia coli (AB1157) we used virus like particles (VLPs) from an oligotrophic marine environment (Mediterranean Sea, West coast of Corsica) and obtained gene transfer frequencies ranging between 10-2 to 10-6 per viral particle. Consequently we had to assume that an important fraction of the VLPs obtained via ultrafiltration (Minitan Ultrafiltration System, Millipore, USA. 30 kDA cut-off filter) from surface seawater have the capability to induce general transduction. In the process of this investigation we made a number of new observations which were not compatible with the concept of general transduction. The obtained transductants were able to produce new VLPs, which had again the capability to induce transduction. In an attempt to characterize these particles we show that their appearance in the experiment was neither related to plaque formation nor to cell lysis and we discuss the concept of transduction in the light of new experimental evidence concerning transducing particles. Furthermore, a preliminary numerical model allowing an estimation of the transduction events, taking place in the water column within a year is presented.

  8. Cationically polymerizable monomers derived from renewable sources

    SciTech Connect

    Crivello, J.V.

    1992-10-01

    The objectives of this project are to design and synthesize novel monomers which orginate from renewable biological sources and to carry out their rapid, efficient, pollution-free and energy efficient cationic polymerization to useful products under the influence of ultraviolet light or heat. A summary of the results of the past year's research on cationically polymerizable monomers derived from renewable sources is presented. Three major areas of investigation corresponding to the different classes of naturally occurring starting materials were investigated; epoxidized terpenes and natural rubber and vinyl ethers from alcohols and carbohydrates.

  9. ABSORPTION METHOD FOR SEPARATING METAL CATIONS

    DOEpatents

    Tompkins, E.R.; Parker, G.W.

    1959-03-10

    An improved method is presented for the chromatographic separation of fission products wherein a substantial reduction in liquid volume is obtained. The process consists in contacting a solution containing fission products with a body of ion-exchange adsorbent to effect adsorption of fission product cations. The loaded exchange resin is then contacted with a small volume of a carboxylic acid eluant, thereby recovering the fission products. The fission product carrying eluate is acidified without increasing its volume to the volume of the original solution, and the acidified eluate is then used as a feed solution for a smaller body of ion-exchange resin effecting readsorption of the fission product cations.

  10. Copper-catalyzed oxidation of a structured lipid-based emulsion containing alpha-tocopherol and citric acid: influence of pH and NaCl.

    PubMed

    Osborn-Barnes, Hannah T; Akoh, Casimir C

    2003-11-01

    The effects of salt and pH on copper-catalyzed lipid oxidation in structured lipid-based emulsions were evaluated. Ten percent oil-in-water emulsions were formulated with a canola oil/caprylic acid structured lipid and stabilized with 0.5% whey protein isolate. alpha-Tocopherol and citric acid were added to the emulsions to determine how changes in pH or the addition of NaCl affected their antioxidant activity. The peroxide values and anisidine values of emulsions stored at 50 degrees C were measured over an 8-day period. Increased lipid oxidation occurred in the pH 7.0 emulsions and when 0.5 M NaCl was added to the pH 3.0 samples. Adding alpha-tocopherol, citric acid, or a combination of the two compounds slowed the formation of hydroperoxides and their subsequent decomposition products in pH 3.0 emulsions.

  11. Microscopic structure of heterogeneous lipid-based formulations revealed by 13C high-resolution solid-state and 1H PFG NMR methods.

    PubMed

    Guillermo, Armel; Gerbaud, Guillaume; Bardet, Michel

    2010-03-01

    Lipid-based formulations such as lip glosses that are very alike on the base of their components may have significant differences in their expected macroscopic properties as cosmetics. To differentiate such formulations, high-resolution (13)C NMR was performed under magic angle spinning to investigate the properties at both molecular and microscopic levels. Temperature studies were carried out and no polymorphism in the solid domains could be evidenced after the thermal treatment performed for obtaining the commercial lip glosses. (13)C NMR spectra also showed that some waxes remain partially solubilized in the oils of formulations. The microscopic structure of the wax-oil liquid domains was worked out on the basis of restricted diffusion properties obtained with proton pulsed-field gradient NMR. Changing a single wax component, in two identical formulations, yields significant morphological differences. In the first one the liquid phase appears as a continuum whereas in the second one, the liquid phase is fractionated into micrometric droplets.

  12. Selection of a discriminant and biorelevant in vitro dissolution test for the development of fenofibrate self-emulsifying lipid-based formulations.

    PubMed

    Pestieau, Aude; Krier, Fabrice; Brouwers, Adeline; Streel, Bruno; Evrard, Brigitte

    2016-09-20

    Fenofibrate, a BCS class II compound, has a low bioavailability especially when taken orally on an empty stomach. The challenge to find a new formulation for providing bioavailability, independent of food, is still ongoing. If the development of a suitable oral delivery formulation of BCS class II compounds is a frequent and great challenge to formulation scientists, the in vitro evaluation of these new formulations is also a great challenge. The purpose of this study was therefore to select an in vitro dissolution test that would be useful and as biorelevant as possible for the development of fenofibrate self-emulsifying lipid-based formulations. In this context, three different fenofibrate formulations, for which in vivo data are available in the literature, were tested using different dissolution tests until we found the one that was the most suitable. As part of this approach, we started with the simplest in vitro dissolution tests and progressed to tests that were increasingly more complex. The first tests were different single phase dissolution tests: a test under sink conditions based on the USP monograph, and different tests under non-sink conditions in non-biorelevant and biorelevant media. Given the inconclusive results obtained with these tests, biphasic dissolution systems were then tested: one with USP apparatus type II alone and another which combined USP apparatus types II and IV. This last combined test seemed the most suitable in vitro dissolution test for the development of the future fenofibrate lipid-based formulations we intend to develop in our own laboratory. PMID:27169683

  13. Iodine status of young Burkinabe children receiving small-quantity lipid-based nutrient supplements and iodised salt: a cluster-randomised trial.

    PubMed

    Hess, Sonja Y; Abbeddou, Souheila; Yakes Jimenez, Elizabeth; Ouédraogo, Jean-Bosco; Brown, Kenneth H

    2015-12-14

    The objective of the present study was to assess the impact of providing small-quantity lipid-based nutrient supplements (SQ-LNS) on the I status of young Burkinabe children. In total, thirty-four communities were assigned to intervention (IC) or non-intervention cohorts (NIC). IC children were randomly assigned to receive 20 g lipid-based nutrient supplements (LNS)/d containing 90 µg I with 0 or 10 mg Zn from 9 to 18 months of age, and NIC children received no SQ-LNS. All the children were exposed to iodised salt through the national salt iodization programme. Spot urinary iodine (UI), thyroid-stimulating hormone (TSH) and total thyroxine (T4) in dried blood spots as well as plasma thyroglobulin (Tg) concentrations were assessed at 9 and 18 months of age among 123 IC and fifty-six NIC children. At baseline and at 18 months, UI, TSH and T4 did not differ between cohorts. Tg concentration was higher in the NIC v. IC at baseline, but this difference did not persist at 18 months of age. In both cohorts combined, the geometric mean of UI was 339·2 (95% CI 298·6, 385·2) µg/l, TSH 0·8 (95% CI 0·7, 0·8) mU/l, T4 118 (95 % CI 114, 122) nmol/l and Tg 26·0 (95% CI 24·3, 27·7) µg/l at 18 months of age. None of the children had elevated TSH at 18 months of age. Marginally more children in NIC (8·9%) had low T4 (15 ppm). A reduction of SQ-LNS I content could be considered in settings with similarly successful salt iodisation programmes.

  14. Selection of a discriminant and biorelevant in vitro dissolution test for the development of fenofibrate self-emulsifying lipid-based formulations.

    PubMed

    Pestieau, Aude; Krier, Fabrice; Brouwers, Adeline; Streel, Bruno; Evrard, Brigitte

    2016-09-20

    Fenofibrate, a BCS class II compound, has a low bioavailability especially when taken orally on an empty stomach. The challenge to find a new formulation for providing bioavailability, independent of food, is still ongoing. If the development of a suitable oral delivery formulation of BCS class II compounds is a frequent and great challenge to formulation scientists, the in vitro evaluation of these new formulations is also a great challenge. The purpose of this study was therefore to select an in vitro dissolution test that would be useful and as biorelevant as possible for the development of fenofibrate self-emulsifying lipid-based formulations. In this context, three different fenofibrate formulations, for which in vivo data are available in the literature, were tested using different dissolution tests until we found the one that was the most suitable. As part of this approach, we started with the simplest in vitro dissolution tests and progressed to tests that were increasingly more complex. The first tests were different single phase dissolution tests: a test under sink conditions based on the USP monograph, and different tests under non-sink conditions in non-biorelevant and biorelevant media. Given the inconclusive results obtained with these tests, biphasic dissolution systems were then tested: one with USP apparatus type II alone and another which combined USP apparatus types II and IV. This last combined test seemed the most suitable in vitro dissolution test for the development of the future fenofibrate lipid-based formulations we intend to develop in our own laboratory.

  15. Cationic Lipid–Nucleic Acid Complexes for Gene Delivery and Silencing: Pathways and Mechanisms for Plasmid DNA and siRNA

    PubMed Central

    Ewert, Kai K.; Zidovska, Alexandra; Ahmad, Ayesha; Bouxsein, Nathan F.; Evans, Heather M.; McAllister, Christopher S.; Samuel, Charles E.; Safinya, Cyrus R.

    2013-01-01

    Motivated by the promises of gene therapy, there is a large interest in developing non-viral lipid-based vectors for therapeutic applications due to their nonimmunogenicity, low toxicity, ease of production, and the potential of transferring large pieces of DNA into cells. In fact, cationic lipid (CL) based vectors are among the prevalent synthetic carriers of nucleic acids (NAs) currently used in human clinical gene therapy trials worldwide. These vectors are studied both for gene delivery with CL–DNA complexes and gene silencing with CL–siRNA (short-interfering RNA) complexes. However, their transfection efficiencies and silencing efficiencies remain low compared to those of engineered viral vectors. This reflects the currently poor understanding of transfection-related mechanisms at the molecular and self-assembled levels, including a lack of knowledge about interactions between membranes and double stranded NAs and between CL–NA complexes and cellular components. In this review, we describe our recent efforts to improve the mechanistic understanding of transfection by CL–NA complexes, which will help to design optimal lipid-based carriers of DNA and siRNA for therapeutic gene delivery and gene silencing. PMID:21504103

  16. Transduction for pheromones in the main olfactory epithelium is mediated by the Ca2+ -activated channel TRPM5.

    PubMed

    López, Fabián; Delgado, Ricardo; López, Roberto; Bacigalupo, Juan; Restrepo, Diego

    2014-02-26

    Growing evidence suggests that the main olfactory epithelium contains a subset of olfactory sensory neurons (OSNs) responding to pheromones. One candidate subpopulation expresses the calcium activated cation channel TRPM5 (transient receptor potential channel M5). Using GFP driven by the TRPM5 promoter in mice, we show that this subpopulation responds to putative pheromones, urine, and major histocompatibility complex peptides, but not to regular odors or a pheromone detected by other species. In addition, this subpopulation of TRPM5-GFP+ OSNs uses novel transduction. In regular OSNs, odorants elicit activation of the cyclic nucleotide-gated (CNG) channel, leading to Ca2+ gating of Cl- channels; in TRPM5-GFP+ OSNs, the Ca2+ -activated Cl- ANO2 (anoctamin 2) channel is not expressed, and pheromones elicit activation of the CNG channel leading to Ca2+ gating of TRPM5. In conclusion, we show that OSNs expressing TRPM5 respond to pheromones, but not to regular odors through the opening of CNG channels leading to Ca2+ gating of TRPM5.

  17. Genetic Analysis of Gravity Signal Transduction in Arabidopsis thaliana Seedlings

    NASA Astrophysics Data System (ADS)

    Boonsirichai, K.; Harrison, B.; Stanga, J.; Young, L.-S.; Neal, C.; Sabat, G.; Murthy, N.; Harms, A.; Sedbrook, J.; Masson, P.

    The primary roots of Arabidopsis thaliana seedlings respond to gravity stimulation by developing a tip curvature that results from differential cellular elongation on opposite flanks of the elongation zone. This curvature appears modulated by a lateral gradient of auxin that originates in the gravity-perceiving cells (statocytes) of the root cap through an apparent lateral repositioning of a component the auxin efflux carrier complex within these cells (Friml et al, 2002, Nature 415: 806-809). Unfortunately, little is known about the molecular mechanisms that govern early phases of gravity perception and signal transduction within the root-cap statocytes. We have used a molecular genetic approach to uncover some of these mechanisms. Mutations in the Arabidopsis ARG1 and ARL2 genes, which encode J-domain proteins, resulted in specific alterations in root and hypocotyl gravitropism, without pleiotropic phenotypes. Interestingly, ARG1 and ARL2 appear to function in the same genetic pathway. A combination of molecular genetic, biochemical and cell-biological approaches were used to demonstrate that ARG1 functions in early phases of gravity signal transduction within the root and hypocotyl statocytes, and is needed for efficient lateral auxin transport within the cap. The ARG1 protein is associated with components of the secretory and/or endosomal pathways, suggesting its role in the recycling of components of the auxin efflux carrier complex between plasma membrane and endosome (Boonsirichai et al, 2003, Plant Cell 15:2612-2625). Genetic modifiers of arg1-2 were isolated and shown to enhance the gravitropic defect of arg1-2, while resulting in little or no gravitropic defects in a wild type ARG1 background. A slight tendency for arg1-2;mar1-1 and arg1-2;mar2-1 double-mutant organs to display an opposite gravitropic response compared to wild type suggests that all three genes contribute to the interpretation of the gravity-vector information by seedling organs. The

  18. Cationic polymer brush-modified cellulose nanocrystals for high-affinity virus binding

    NASA Astrophysics Data System (ADS)

    Rosilo, Henna; McKee, Jason R.; Kontturi, Eero; Koho, Tiia; Hytönen, Vesa P.; Ikkala, Olli; Kostiainen, Mauri A.

    2014-09-01

    Surfaces capable of high-affinity binding of biomolecules are required in several biotechnological applications, such as purification, transfection, and sensing. Therein, the rod-shaped, colloidal cellulose nanocrystals (CNCs) are appealing due to their large surface area available for functionalization. In order to exploit electrostatic binding, their intrinsically anionic surfaces have to be cationized as biological supramolecules are predominantly anionic. Here we present a facile way to prepare cationic CNCs by surface-initiated atom-transfer radical polymerization of poly(N,N-dimethylaminoethyl methacrylate) and subsequent quaternization of the polymer pendant amino groups. The cationic polymer brush-modified CNCs maintained excellent dispersibility and colloidal stability in water and showed a ζ-potential of +38 mV. Dynamic light scattering and electron microscopy showed that the modified CNCs electrostatically bind cowpea chlorotic mottle virus and norovirus-like particles with high affinity. Addition of only a few weight percent of the modified CNCs in water dispersions sufficed to fully bind the virus capsids to form micrometer-sized assemblies. This enabled the concentration and extraction of the virus particles from solution by low-speed centrifugation. These results show the feasibility of the modified CNCs in virus binding and concentrating, and pave the way for their use as transduction enhancers for viral delivery applications.Surfaces capable of high-affinity binding of biomolecules are required in several biotechnological applications, such as purification, transfection, and sensing. Therein, the rod-shaped, colloidal cellulose nanocrystals (CNCs) are appealing due to their large surface area available for functionalization. In order to exploit electrostatic binding, their intrinsically anionic surfaces have to be cationized as biological supramolecules are predominantly anionic. Here we present a facile way to prepare cationic CNCs by surface

  19. Cation Selectivity in Biological Cation Channels Using Experimental Structural Information and Statistical Mechanical Simulation.

    PubMed

    Finnerty, Justin John; Peyser, Alexander; Carloni, Paolo

    2015-01-01

    Cation selective channels constitute the gate for ion currents through the cell membrane. Here we present an improved statistical mechanical model based on atomistic structural information, cation hydration state and without tuned parameters that reproduces the selectivity of biological Na+ and Ca2+ ion channels. The importance of the inclusion of step-wise cation hydration in these results confirms the essential role partial dehydration plays in the bacterial Na+ channels. The model, proven reliable against experimental data, could be straightforwardly used for designing Na+ and Ca2+ selective nanopores. PMID:26460827

  20. Restructuring of a peat in interaction with multivalent cations: effect of cation type and aging time.

    PubMed

    Kunhi Mouvenchery, Yamuna; Jaeger, Alexander; Aquino, Adelia J A; Tunega, Daniel; Diehl, Dörte; Bertmer, Marko; Schaumann, Gabriele Ellen

    2013-01-01

    It is assumed to be common knowledge that multivalent cations cross-link soil organic matter (SOM) molecules via cation bridges (CaB). The concept has not been explicitly demonstrated in solid SOM by targeted experiments, yet. Therefore, the requirements for and characteristics of CaB remain unidentified. In this study, a combined experimental and molecular modeling approach was adopted to investigate the interaction of cations on a peat OM from physicochemical perspective. Before treatment with salt solutions of Al(3+), Ca(2+) or Na(+), respectively, the original exchangeable cations were removed using cation exchange resin. Cation treatment was conducted at two different values of pH prior to adjusting pH to 4.1. Cation sorption is slower (>2 h) than deprotonation of functional groups (<2 h) and was described by a Langmuir model. The maximum uptake increased with pH of cation addition and decreased with increasing cation valency. Sorption coefficients were similar for all cations and at both pH. This contradicts the general expectations for electrostatic interactions, suggesting that not only the interaction chemistry but also spatial distribution of functional groups in OM determines binding of cations in this peat. The reaction of contact angle, matrix rigidity due to water molecule bridges (WaMB) and molecular mobility of water (NMR analysis) suggested that cross-linking via CaB has low relevance in this peat. This unexpected finding is probably due to the low cation exchange capacity, resulting in low abundance of charged functionalities. Molecular modeling demonstrates that large average distances between functionalities (∼3 nm in this peat) cannot be bridged by CaB-WaMB associations. However, aging strongly increased matrix rigidity, suggesting successive increase of WaMB size to connect functionalities and thus increasing degree of cross-linking by CaB-WaMB associations. Results thus demonstrated that the physicochemical structure of OM is decisive for

  1. Method for encapsulating and isolating hazardous cations, medium for encapsulating and isolating hazardous cations

    SciTech Connect

    Wasserman, S.R.; Anderson, K.B.; Song, K.; Yuchs, S.E.; Marshall, C.L.

    1996-12-31

    The problems associated with the disposal of toxic metals in an environmentally acceptable manner continues to plague industry. Such metals as nickel, vanadium, molybdenum, cobalt, iron, and antimony present physiological and ecological challenges that are best addressed through minimization of exposure and dispersion. A method for encapsulating hazardous cations is provided comprising supplying a pretreated substrate containing the cations; contacting the substrate with an organo-silane compound to form a coating on the substrate; and allowing the coating to cure. A medium for containing hazardous cations is also provided, comprising a substrate having ion-exchange capacity and a silane-containing coating on the substrate.

  2. Cation Selectivity in Biological Cation Channels Using Experimental Structural Information and Statistical Mechanical Simulation

    PubMed Central

    Finnerty, Justin John

    2015-01-01

    Cation selective channels constitute the gate for ion currents through the cell membrane. Here we present an improved statistical mechanical model based on atomistic structural information, cation hydration state and without tuned parameters that reproduces the selectivity of biological Na+ and Ca2+ ion channels. The importance of the inclusion of step-wise cation hydration in these results confirms the essential role partial dehydration plays in the bacterial Na+ channels. The model, proven reliable against experimental data, could be straightforwardly used for designing Na+ and Ca2+ selective nanopores. PMID:26460827

  3. Viscoelastic cationic polymers containing the urethane linkage

    NASA Technical Reports Server (NTRS)

    Rembaum, A. (Inventor)

    1972-01-01

    A method for the synthesis and manufacturing of elastomeric compositions and articles containing quaternary nitrogen centers and condensation residues along the polymeric backbone of the centers is presented. Linear and cross-linked straight chain and block polymers having a wide damping temperature range were synthesized. Formulae for the viscoelastic cationic polymers are presented.

  4. NMR studies of cation transport across membranes

    SciTech Connect

    Shochet, N.R.

    1985-01-01

    /sup 23/Na NMR Studies of cation transport across membranes were conducted both on model and biological membranes. Two ionophores, the carrier monensin and the channel-former gramicidin, were chosen to induce cation transport in large unilamellar phosphatidylcholine vesicles. The distinction between the NMR signals arising from the two sides of the membrane was achieved by the addition of an anionic paramagnetic shift reagent to the outer solution. The kinetics of the cation transport across the membrane was observed simultaneously monitoring the changes in the /sup 23/Na NMR signals of both compartments. Two mathematical models were developed for the estimation of the transport parameters of the monensin- and gramicidin-induced cation transport. The models were able to fit the experimental data very well. A new method for the estimation of the volume trapped inside the vesicles was developed. The method uses the relative areas of the intra- and extravesicular NMR signals arising from a suspension of vesicles bathed in the same medium they contain, as a measure for the relative volumes of these compartments. Sodium transport across biological membranes was studied by /sup 23/ NMR, using suspensions of cultured nerve cells. The sodium influx through voltage-gated channels was studied using the channel modifier batrachotoxin in combination with scorpion toxin.

  5. Anionic/cationic complexes in hair care.

    PubMed

    O'Lenick, Tony

    2011-01-01

    The formulation of cosmetic products is always more complicated than studying the individual components in aqueous solution. This is because there are numerous interactions between the components, which make the formulation truly more than the sum of the parts. This article will look at interactions between anionic and cationic surfactants and offer insights into how to use these interactions advantageously in making formulations.

  6. ADSORPTION OF ORGANIC CATIONS TO NATURAL MATERIALS

    EPA Science Inventory

    The factors that control the extent of adsorption of amphiphilic organic cations on environmental and pristine surfaces have been studied. The sorbents were kaolinite, montmorillonite, two aquifer materials, and a soil; solutions contained various concentrations of NaCl and CaCl,...

  7. Impaired Transduction of R213 and Its Recovery by a Homologous Resident R Factor

    PubMed Central

    Yoshikawa, Masanosuke; Hirota, Yukinori

    1971-01-01

    Transduction by Plkc of drug-resistance markers of the factor R213 was shown to occur at an exceptionally low frequency (at less than 10−8 of the input phage), and they could not be transduced by P22. When the recipient cells carried a homologous R factor derived from R213, markers were transduced by Plkc at a normal frequency (at about 10−5 to 10−6 of the input phage). Derivative R factors, transducible by Plkc at a normal frequency but being transferred by conjugation at a frequency lower than that of the original R213, were obtained. This type of transductant often segregated R− cells. In addition, several transductants contained R factors which were transferred normally by conjugation but were transduced by Plkc at as low a frequency as the original R213. This type of transductant was an effective recipient for transduction by Plkc of R213 when apparently “cured” by acridine treatment. No such effective “cured” recipients were obtained from the transductants with derivatives of R213 transducible at a normal frequency. Two possible interpretations are presented: (i) R213 produces a bacteriocin-like substance upon transduction, or (ii) the genome size of R213 is too large for all of its determinants to be transduced. PMID:4929864

  8. Optimization of the transductional efficiency of lentiviral vectors: effect of sera and polycations.

    PubMed

    Denning, Warren; Das, Suvendu; Guo, Siqi; Xu, Jun; Kappes, John C; Hel, Zdenek

    2013-03-01

    Lentiviral vectors are widely used as effective gene-delivery vehicles. Optimization of the conditions for efficient lentiviral transduction is of a high importance for a variety of research applications. Presence of positively charged polycations reduces the electrostatic repulsion forces between a negatively charged cell and an approaching enveloped lentiviral particle resulting in an increase in the transduction efficiency. Although a variety of polycations are commonly used to enhance the transduction with retroviruses, the relative effect of various types of polycations on the efficiency of transduction and on the potential bias in the determination of titer of lentiviral vectors is not fully understood. Here, we present data suggesting that DEAE-dextran provides superior results in enhancing lentiviral transduction of most tested cell lines and primary cell cultures. Specific type and source of serum affects the efficiency of transduction of target cell populations. Non-specific binding of enhanced green fluorescent protein (EGFP)-containing membrane aggregates in the presence of DEAE-dextran does not significantly affect the determination of the titer of EGFP-expressing lentiviral vectors. In conclusion, various polycations and types of sera should be tested when optimizing lentiviral transduction of target cell populations.

  9. Improved transduction efficiencies of adeno-associated virus vectors by synthetic cell-permeable peptides.

    PubMed

    Tabata, Kitako; Sugano, Eriko; Murakami, Fumika; Yamashita, Tetsuro; Ozaki, Taku; Tomita, Hiroshi

    2016-09-30

    Various serotypes of adeno-associated virus (AAV) vectors have been used for gene therapy and as research tools. Among these serotypes, the AAV type 2 vector has been used successfully in human gene therapies. However, the transduction efficiency of AAV2 depends on the cell type, and this poses a problem in the efficacy of gene therapy. To improve the transduction efficiency of AAV2, we designed a small peptide consisting of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor peptide and the HIV-Tat sequence Tat-Y1068. Pre- or co-treatment of CYNOM-K1 cells from cynomolgus monkey embryo skin with Tat-Y1068 increased the transduction efficiencies in a dose-dependent manner and caused p38 phosphorylation. The transduction efficiency of AAV2 into the rat fibroblast cell line RAT-1 highly expressing EGFR was less than the transduction efficiency of AAV2 into CYNOM-K1 cells. Tat-Y1068 increased the transduction efficiency in RAT-1 cells in the same manner as in CYNOM-K1 cells. In conclusion, cell-permeable peptides possessing the EGFR tyrosine kinase inhibitor function might serve as a useful ingredient of AAV2 vector solution for increasing the transduction efficiency of gene therapies.

  10. Improved transduction efficiencies of adeno-associated virus vectors by synthetic cell-permeable peptides.

    PubMed

    Tabata, Kitako; Sugano, Eriko; Murakami, Fumika; Yamashita, Tetsuro; Ozaki, Taku; Tomita, Hiroshi

    2016-09-30

    Various serotypes of adeno-associated virus (AAV) vectors have been used for gene therapy and as research tools. Among these serotypes, the AAV type 2 vector has been used successfully in human gene therapies. However, the transduction efficiency of AAV2 depends on the cell type, and this poses a problem in the efficacy of gene therapy. To improve the transduction efficiency of AAV2, we designed a small peptide consisting of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor peptide and the HIV-Tat sequence Tat-Y1068. Pre- or co-treatment of CYNOM-K1 cells from cynomolgus monkey embryo skin with Tat-Y1068 increased the transduction efficiencies in a dose-dependent manner and caused p38 phosphorylation. The transduction efficiency of AAV2 into the rat fibroblast cell line RAT-1 highly expressing EGFR was less than the transduction efficiency of AAV2 into CYNOM-K1 cells. Tat-Y1068 increased the transduction efficiency in RAT-1 cells in the same manner as in CYNOM-K1 cells. In conclusion, cell-permeable peptides possessing the EGFR tyrosine kinase inhibitor function might serve as a useful ingredient of AAV2 vector solution for increasing the transduction efficiency of gene therapies. PMID:27614311

  11. Process and apparatus for the production of Bi-213 cations

    DOEpatents

    Horwitz, E.P.; Hines, J.J.; Chiarizia, R.; Dietz, M.

    1998-12-29

    A process for producing substantially impurity-free Bi-213 cations is disclosed. An aqueous acid feed solution containing Ac-225 cations is contacted with an ion exchange medium to bind the Ac-225 cations and form an Ac-225-laden ion exchange medium. The bound Ac-225 incubates on the ion exchange medium to form Bi-213 cations by radioactive decay. The Bi-213 cations are then recovered from the Ac-225-laden ion exchange medium to form a substantially impurity-free aqueous Bi-213 cation acid solution. An apparatus for carrying out this process is also disclosed. 7 figs.

  12. Process and apparatus for the production of BI-213 cations

    DOEpatents

    Horwitz, E. Philip; Hines, John J.; Chiarizia, Renato; Dietz, Mark

    1998-01-01

    A process for producing substantially impurity-free Bi-213 cations is disclosed. An aqueous acid feed solution containing Ac-225 cations is contacted with an ion exchange medium to bind the Ac-225 cations and form an Ac-225-laden ion exchange medium. The bound Ac-225 incubates on the ion exchange medium to form Bi-213 cations by radioactive decay. The Bi-213 cations are then recovered from the Ac-225-laden ion exchange medium to form a substantially impurity-free aqueous Bi-213 cation acid solution. An apparatus for carrying out this process is also disclosed.

  13. Cationic lipids and cationic ligands induce DNA helix denaturation: detection of single stranded regions by KMnO4 probing.

    PubMed

    Prasad, T K; Gopal, Vijaya; Rao, N Madhusudhana

    2003-09-25

    Cationic lipids and cationic polymers are widely used in gene delivery. Using 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) as a cationic lipid, we have investigated the stability of the DNA in DOTAP:DNA complexes by probing with potassium permanganate (KMnO4). Interestingly, thymidines followed by a purine showed higher susceptibility to cationic ligand-mediated melting. Similar studies performed with other water-soluble cationic ligands such as polylysine, protamine sulfate and polyethyleneimine also demonstrated melting of the DNA but with variations. Small cations such as spermine and spermidine and a cationic detergent, cetyl trimethylammonium bromide, also rendered the DNA susceptible to modification by KMnO4. The data presented here provide direct proof for melting of DNA upon interaction with cationic lipids. Structural changes subsequent to binding of cationic lipids/ligands to DNA may lead to instability and formation of DNA bubbles in double-stranded DNA.

  14. Effects of arsenite in astrocytes on neuronal signaling transduction.

    PubMed

    Wang, Yan; Zhao, Fenghong; Liao, Yingjun; Jin, Yaping; Sun, Guifan

    2013-01-01

    The main purpose of this study was to test the hypothesis that arsenite induces neurotoxicity via effects on astrocytes. Astrocytes were exposed to 0, 5 or 10 μM arsenite in medium for 24 h, and then astrocyte-conditioned medium (ACM) was collected after incubation with fresh medium for 6 h. Primary neuron cultures were divided into four groups due to ACM, which were neurons without ACM exposure (group I) and neurons exposed to ACM from 0, 5 or 10 μM arsenite treated astrocytes (group II-IV). Protein expression of N-methyl-d-aspartate receptors (NR1, NR2A, NR2B), calmodulin-dependent protein kinase II (CaMKII) and adenylate cyclase (AC) in neurons were measured after incubation with ACM for 4, 8 or 12 h. Morphological changes and synaptic formation were observed after a 72 h-incubation with ACM. Compared to group II, synaptic formation and protein expression of NR2A, NR2B, CaMKII and AC in group III and IV were significantly suppressed. Moreover, synaptic formation and protein expression of CaMKII and AC in group II were significantly enhanced when compared with group I. Taken together, findings from this study suggested that arsenic in astrocytes might impair synaptic formation through disturbing astrocytic effects on neuronal signal transduction.

  15. Bacteriophage-associated gene transfer in pneumococcus: transduction or pseudotransduction?

    PubMed Central

    Porter, R D; Shoemaker, N B; Rampe, G; Guild, W R

    1979-01-01

    Lysates of pneumococcal phage PG24 transferred genes from one host to another in a process with many of the properties of generalized transduction, in that the host genes were packaged in DNase-resistant particles that closely resembled infectious phage in physical properties, adsorbed to the recipient cells like phage, and were inhibited by antisera to the phage and by trypsin. However, phage processes did not complete the transfer of host DNA as they did phage DNA. Instead, gene transfer required development of competence and entry of the host DNA by the endonuclease-dependent pathway used for transforming and transfecting DNA. This process often occurred on the assay plate hours after adsorption of the particles to the cells, and the transfer was DNase sensitive if challenged at this time. Phenotypic expression was therefore also delayed. The product of entry was like that in transformation, a single strand of DNA that integrates by formation of a hex-sensitive donor-recipient heteroduplex. Whether this gene transfer process is unique to this system or is only the first one described is not clear. The term "pseudotransduction" may be useful in calling attention to its unexpected features. The DNA of PG24 phage has anomalous physical properties reflecting unusual bases. Images PMID:33154

  16. Allostery Wiring Map for Kinesin Energy Transduction and Its Evolution*

    PubMed Central

    Richard, Jessica; Kim, Elizabeth D.; Nguyen, Hoang; Kim, Catherine D.; Kim, Sunyoung

    2016-01-01

    How signals between the kinesin active and cytoskeletal binding sites are transmitted is an open question and an allosteric question. By extracting correlated evolutionary changes within 700+ sequences, we built a model of residues that are energetically coupled and that define molecular routes for signal transmission. Typically, these coupled residues are located at multiple distal sites and thus are predicted to form a complex, non-linear network that wires together different functional sites in the protein. Of note, our model connected the site for ATP hydrolysis with sites that ultimately utilize its free energy, such as the microtubule-binding site, drug-binding loop 5, and necklinker. To confirm the calculated energetic connectivity between non-adjacent residues, double-mutant cycle analysis was conducted with 22 kinesin mutants. There was a direct correlation between thermodynamic coupling in experiment and evolutionarily derived energetic coupling. We conclude that energy transduction is coordinated by multiple distal sites in the protein rather than only being relayed through adjacent residues. Moreover, this allosteric map forecasts how energetic orchestration gives rise to different nanomotor behaviors within the superfamily. PMID:27507814

  17. PII Signal Transduction Proteins, Pivotal Players in Microbial Nitrogen Control

    PubMed Central

    Arcondéguy, Tania; Jack, Rachael; Merrick, Mike

    2001-01-01

    The PII family of signal transduction proteins are among the most widely distributed signal proteins in the bacterial world. First identified in 1969 as a component of the glutamine synthetase regulatory apparatus, PII proteins have since been recognized as playing a pivotal role in control of prokaryotic nitrogen metabolism. More recently, members of the family have been found in higher plants, where they also potentially play a role in nitrogen control. The PII proteins can function in the regulation of both gene transcription, by modulating the activity of regulatory proteins, and the catalytic activity of enzymes involved in nitrogen metabolism. There is also emerging evidence that they may regulate the activity of proteins required for transport of nitrogen compounds into the cell. In this review we discuss the history of the PII proteins, their structures and biochemistry, and their distribution and functions in prokaryotes. We survey data emerging from bacterial genome sequences and consider other likely or potential targets for control by PII proteins. PMID:11238986

  18. Impaired phospholipid-related signal transduction in advanced Huntington's disease.

    PubMed

    Puri, B K

    2001-09-01

    The aim of this study was to test the hypothesis that Huntington's disease is associated with impaired phospholipid-related signal transduction using the niacin skin flush test. This is the first reported use of this test in this patient group. The response to topical aqueous methyl nicotinate solution was recorded at 5 min intervals over 20 min in six in-patients with advanced (stage III) Huntington's disease and in 14 age- and sex-matched normal individuals with no history of this or any other major neurological disorder. The volumetric niacin response (VNR) (mean +/- S.E.M.) in the patients with Huntington's disease, 16.3 +/- 2.6 mol x s x l(-1), was significantly lower than the mean VNR of 28.3 +/- 2.1 mol x s x l(-1) in the control group (P = 0.004). These results are consistent with the conclusion that Huntington's disease may be associated with an abnormality of neuronal membrane fatty acid metabolism, possibly as a consequence of an as yet unidentified action of huntingtin.

  19. Bacterial stimulus perception and signal transduction: response to osmotic stress.

    PubMed

    Krämer, Reinhard

    2010-08-01

    When exposed to osmotic stress from the environment, bacteria act to maintain cell turgor and hydration by responding both on the level of gene transcription and protein activity. Upon a sudden decrease in external osmolality, internal solutes are released by the action of membrane embedded mechanosensitive channels. In response to an osmotic upshift, the concentration of osmolytes in the cytoplasm is increased both by de novo synthesis and by active uptake. In order to coordinate these processes of osmoregulation, cells are equipped with systems and mechanisms of sensing physical stimuli correlated to changes in the external osmolality (osmosensing), with pathways to transduce these stimuli into useful signals which can be processed in the cell (signal transduction), and mechanisms of regulating proper responses in the cell to recover from the environmental stress and to maintain all necessary physiological functions (osmoregulation). These processes will be described by a number of representative examples, mainly of osmoreactive transport systems with a focus on available data of their molecular mechanism.

  20. Analysis of intercellular signal transduction in the tumor microenvironment

    PubMed Central

    2013-01-01

    Background Recent cancer studies revealed, the interaction between pancreatic cancer cells and pancreatic stellate cells is of importance in the cancer progression. The activation of stellate cells is mediated by some growth factors and cytokines secreted by the cancer cells. In turn, the activated stellate cells will synthesize and secrete multiple growth factors to continuously stimulate the growth of surrounding cancer cells through paracrine pathways. The mechanism behind the evolution of stellate cells from quiescent state to a cancer-associated phenotype is still not well understood. Results To systematically investigate the interaction between cancer cells and stellate cells, we constructed a multicellular discrete value model, which is composed of several intracellular and intercellular signaling pathways that are frequently mutated in the pancreatic cancer, to study the cell cycle progression and angiogenesis. We, then, introduced and applied a formal verification technique, Symbolic Model Checking, to automatically analyze the cells' proliferation, angiogenesis and apoptosis in the proposed signal transduction model of tumor microenvironment. Conclusions Our studies predicted some important temporal logic properties and dynamic behaviors in the pancreatic cancer cells and stellate cells. The verification technique identified several signaling components, including the RAS, RAGE, AKT, IKK, DVL, RB and PTEN, whose mutation or loss of function can promote cell growth and inhibit apoptosis, some of which have been confirmed by existing experiments. Our formal studies demonstrated that, the bidirectional interaction between cancer cells and stellate cells could significantly increase cell proliferation, inhibit apoptosis, induce tumor angiogenesis, and promote cancer metastasis. PMID:24555417

  1. NO, nitrotyrosine, and cyclic GMP in signal transduction

    NASA Technical Reports Server (NTRS)

    Hanafy, K. A.; Krumenacker, J. S.; Murad, F.

    2001-01-01

    Over the past 25 years, the role of nitric oxide (NO) in biology has evolved from being recognized as an environmental pollutant to an endogenously produced substance involved in cell communication and signal transduction. NO is produced by a family of enzymes called nitric oxide synthases (NOSs), which can be stimulated by a variety of factors that mediate responses to various stimuli. NO can initiate its biological effects through activation of the heterodimeric enzyme, soluble guanylyl cyclase (sGC), or through several other chemical reactions. Activation of sGC results in the production of 3',5'-cyclic guanosine monophosphate (cGMP), an intracellular second messenger signaling molecule, which can subsequently mediate such diverse physiological events such as vasodilatation and immunomodulation. Chemically reactive NO can affect physiological changes through modifications to cellular proteins, one of which is tyrosine nitration. The demonstration that NO is involved in so many biological pathways indicates the importance of this endogenously produced substance, and suggests that there is much more to be discovered about its role in biology in years to come.

  2. Signal transduction molecule patterns indicating potential glioblastoma therapy approaches

    PubMed Central

    Cruceru, Maria Linda; Enciu, Ana-Maria; Popa, Adrian Claudiu; Albulescu, Radu; Neagu, Monica; Tanase, Cristiana Pistol; Constantinescu, Stefan N

    2013-01-01

    Purpose The expression of an array of signaling molecules, along with the assessment of real-time cell proliferation, has been performed in U87 glioma cell line and in patients’ glioblastoma established cell cultures in order to provide a better understanding of cellular and molecular events involved in glioblastoma pathogenesis. Experimental therapy was performed using a phosphatidylinositol-3′-kinase (PI3K) inhibitor. Patients and methods xMAP technology was employed to assess expression levels of several signal transduction molecules and real-time xCELLigence platform for cell behavior. Results PI3K inhibition induced the most significant effects on global signaling pathways in patient-derived cell cultures, especially on members of the mitogen-activated protein-kinase family, P70S6 serine-threonine kinase, and cAMP response element-binding protein expression and further prevented tumor cell proliferation. Conclusion The PI3K pathway might be a prime target for glioblastoma treatment. PMID:24348050

  3. Transduction of Entangled Images by Localized Surface Plasmons

    NASA Astrophysics Data System (ADS)

    Dowran, Mohammadjavad; Holtfrerich, Matthew; Lawrie, Benjamin; Davidson, Roderick; Pooser, Raphael; Marino, Alberto

    2016-05-01

    Quantum plasmonics has attracted broad interest in recent years, motivated by nano-imaging and sub-wavelength photonic circuits. The potential for nanoscale quantum information processing and quantum plasmonic sensing has led to the study of the interface between quantum optics and plasmonics. We study the interface between continuous variable entangled images and localized surface plasmons (LSPs). We generate entangled images with four-wave mixing in hot Rb atoms. The entangled images are sent through two spatially separated plasmonic structures, which consist of an array of triangular nanoholes in a silver metal film designed to excite LSPs. After transduction through the plasmonic structure, mediated by extraordinary optical transmission (EOT), the entanglement properties of the light are characterized. We show that both the entanglement and spatial properties of the light are preserved by the LSPs. This results show that the transfer of entanglement and quantum information from multi-spatial mode photons to LSPs and back to photons is a coherent process that preserves the spatial quantum information of the incident light. By addressing two spatially separated plasmonic structures, the entanglement is effectively transferred to the plasmons for a short period of time. Work supported by the W.M. Keck Foundation.

  4. Electronic transduction of proton translocations in nanoassembled lamellae of bacteriorhodopsin.

    PubMed

    Palazzo, Gerardo; Magliulo, Maria; Mallardi, Antonia; Angione, Maria Daniela; Gobeljic, Danka; Scamarcio, Gaetano; Fratini, Emiliano; Ridi, Francesca; Torsi, Luisa

    2014-08-26

    An organic field-effect transistor (OFET) integrating bacteriorhodopsin (bR) nanoassembled lamellae is proposed for an in-depth study of the proton translocation processes occurring as the bioelectronic device is exposed either to light or to low concentrations of general anesthetic vapors. The study involves the morphological, structural, electrical, and spectroscopic characterizations necessary to assess the functional properties of the device as well as the bR biological activity once integrated into the functional biointerlayer (FBI)-OFET structure. The electronic transduction of the protons phototranslocation is shown as a current increase in the p-type channel only when the device is irradiated with photons known to trigger the bR photocycle, while Raman spectroscopy reveals an associated C═C isomer switch. Notably, higher energy photons bring the cis isomer back to its trans form, switching the proton pumping process off. The investigation is extended also to the study of a PM FBI-OFET exposed to volatile general anesthetics such as halothane. In this case an electronic current increase is seen upon exposure to low, clinically relevant, concentrations of anesthetics, while no evidence of isomer-switching is observed. The study of the direct electronic detection of the two different externally triggered proton translocation effects allows gathering insights into the underpinning of different bR molecular switching processes. PMID:25077939

  5. Signal transduction in cells of the immune system in microgravity

    PubMed Central

    Ullrich, Oliver; Huber, Kathrin; Lang, Kerstin

    2008-01-01

    Life on Earth developed in the presence and under the constant influence of gravity. Gravity has been present during the entire evolution, from the first organic molecule to mammals and humans. Modern research revealed clearly that gravity is important, probably indispensable for the function of living systems, from unicellular organisms to men. Thus, gravity research is no more or less a fundamental question about the conditions of life on Earth. Since the first space missions and supported thereafter by a multitude of space and ground-based experiments, it is well known that immune cell function is severely suppressed in microgravity, which renders the cells of the immune system an ideal model organism to investigate the influence of gravity on the cellular and molecular level. Here we review the current knowledge about the question, if and how cellular signal transduction depends on the existence of gravity, with special focus on cells of the immune system. Since immune cell function is fundamental to keep the organism under imnological surveillance during the defence against pathogens, to investigate the effects and possible molecular mechanisms of altered gravity is indispensable for long-term space flights to Earth Moon or Mars. Thus, understanding the impact of gravity on cellular functions on Earth will provide not only important informations about the development of life on Earth, but also for therapeutic and preventive strategies to cope successfully with medical problems during space exploration. PMID:18957108

  6. In search of cellular control: signal transduction in context

    NASA Technical Reports Server (NTRS)

    Ingber, D.

    1998-01-01

    The field of molecular cell biology has experienced enormous advances over the last century by reducing the complexity of living cells into simpler molecular components and binding interactions that are amenable to rigorous biochemical analysis. However, as our tools become more powerful, there is a tendency to define mechanisms by what we can measure. The field is currently dominated by efforts to identify the key molecules and sequences that mediate the function of critical receptors, signal transducers, and molecular switches. Unfortunately, these conventional experimental approaches ignore the importance of supramolecular control mechanisms that play a critical role in cellular regulation. Thus, the significance of individual molecular constituents cannot be fully understood when studied in isolation because their function may vary depending on their context within the structural complexity of the living cell. These higher-order regulatory mechanisms are based on the cell's use of a form of solid-state biochemistry in which molecular components that mediate biochemical processing and signal transduction are immobilized on insoluble cytoskeletal scaffolds in the cytoplasm and nucleus. Key to the understanding of this form of cellular regulation is the realization that chemistry is structure and hence, recognition of the the importance of architecture and mechanics for signal integration and biochemical control. Recent work that has unified chemical and mechanical signaling pathways provides a glimpse of how this form of higher-order cellular control may function and where paths may lie in the future.

  7. The interleukin-4 receptor: signal transduction by a hematopoietin receptor.

    PubMed

    Keegan, A D; Pierce, J H

    1994-02-01

    Over the last several years, the receptors for numerous cytokines have been molecularly characterized. Analysis of their amino acid sequences shows that some of these receptors bear certain motifs in their extracellular domains that define a family of receptors called the Hematopoietin receptor superfamily. Significant advances in characterizing the structure, function, and mechanisms of signal transduction have been made for several members of this family. The purpose of this review is to discuss the recent advances made for one of the family members, the interleukin (IL) 4 receptor. Other receptor systems have recently been reviewed elsewhere. The IL-4 receptor consists of, at the minimum, the cloned 140 kDa IL-4-binding chain with the potential for associating with other chains. The IL-4 receptor transduces its signal by activating a tyrosine kinase that phosphorylates cellular substrates, including the receptor itself, and the 170 kDa substrate called 4PS. Phosphorylated 4PS interacts with the SH2 domain of the enzyme PI-3'-kinase and increases its enzymatic activity. These early events in the IL-4 receptor initiated signaling pathway may trigger a series of signals that will ultimately lead to an IL-4 specific biologic outcome.

  8. Effect of monovalent cations on the kinetics of hypoxic conformational change of mitochondrial complex I

    PubMed Central

    Stepanova, Anna; Valls, Alba; Galkin, Alexander

    2015-01-01

    Mitochondrial complex I is a large, membrane-bound enzyme central to energy metabolism, and its dysfunction is implicated in cardiovascular and neurodegenerative diseases. An interesting feature of mammalian complex I is the so-called A/D transition, when the idle enzyme spontaneously converts from the active (A) to the de-active, dormant (D) form. The A/D transition plays an important role in tissue response to ischemia and rate of the conversion can be a crucial factor determining outcome of ischemia/reperfusion. Here, we describe the effects of alkali cations on the rate of the D-to-A transition to define whether A/D conversion may be regulated by sodium. At neutral pH (7–7.5) sodium resulted in a clear increase of rates of activation (D-to-A conversion) while other cations had minor effects. The stimulating effect of sodium in this pH range was not caused by an increase in ionic strength. EIPA, an inhibitor of Na+/H+ antiporters, decreased the rate of D-to-A conversion and sodium partially eliminated this effect of EIPA. At higher pH (> 8.0), acceleration of the D-to-A conversion by sodium was abolished, and all tested cations decreased the rate of activation, probably due to the effect of ionic strength. The implications of this finding for the mechanism of complex I energy transduction and possible physiological importance of sodium stimulation of the D-to-A conversion at pathophysiological conditions in vivo are discussed. PMID:26009015

  9. Dendritic Cells Stimulated by Cationic Liposomes.

    PubMed

    Vitor, Micaela Tamara; Bergami-Santos, Patrícia Cruz; Cruz, Karen Steponavicius Piedade; Pinho, Mariana Pereira; Barbuto, José Alexandre Marzagão; De La Torre, Lucimara Gaziola

    2016-01-01

    Immunotherapy of cancer aims to harness the immune system to detect and destroy cancer cells. To induce an immune response against cancer, activated dendritic cells (DCs) must present tumor antigens to T lymphocytes of patients. However, cancer patients' DCs are frequently defective, therefore, they are prone to induce rather tolerance than immune responses. In this context, loading tumor antigens into DCs and, at the same time, activating these cells, is a tempting goal within the field. Thus, we investigated the effects of cationic liposomes on the DCs differentiation/maturation, evaluating their surface phenotype and ability to stimulate T lymphocytes proliferation in vitro. The cationic liposomes composed by egg phosphatidylcholine, 1,2-dioleoyl-3-trimethylammonium propane and 1,2-dioleoylphosphatidylethanolamine (50/25/25% molar) were prepared by the thin film method followed by extrusion (65 nm, polydispersity of 0.13) and by the dehydration-rehydration method (95% of the population 107 nm, polydispersity of 0.52). The phenotypic analysis of dendritic cells and the analysis of T lymphocyte proliferation were performed by flow cytometry and showed that both cationic liposomes were incorporated and activated dendritic cells. Extruded liposomes were better incorporated and induced higher CD86 expression for dendritic cells than dehydrated-rehydrated vesicles. Furthermore, dendritic cells which internalized extruded liposomes also provided stronger T lymphocyte stimulation. Thus, cationic liposomes with a smaller size and polydispersity seem to be better incorporated by dendritic cells. Hence, these cationic liposomes could be used as a potential tool in further cancer immunotherapy strategies and contribute to new strategies in immunotherapy. PMID:27398454

  10. Graph Regularized Meta-path Based Transductive Regression in Heterogeneous Information Network

    PubMed Central

    Wan, Mengting; Ouyang, Yunbo; Kaplan, Lance; Han, Jiawei

    2015-01-01

    A number of real-world networks are heterogeneous information networks, which are composed of different types of nodes and links. Numerical prediction in heterogeneous information networks is a challenging but significant area because network based information for unlabeled objects is usually limited to make precise estimations. In this paper, we consider a graph regularized meta-path based transductive regression model (Grempt), which combines the principal philosophies of typical graph-based transductive classification methods and transductive regression models designed for homogeneous networks. The computation of our method is time and space efficient and the precision of our model can be verified by numerical experiments. PMID:26705510

  11. Modeling Signal Transduction Networks: A comparison of two Stochastic Kinetic Simulation Algorithms

    SciTech Connect

    Pettigrew, Michel F.; Resat, Haluk

    2005-09-15

    Simulations of a scalable four compartment reaction model based on the well known epidermal growth factor receptor (EGFR) signal transduction system are used to compare two stochastic algorithms ? StochSim and the Gibson-Gillespie. It is concluded that the Gibson-Gillespie is the algorithm of choice for most realistic cases with the possible exception of signal transduction networks characterized by a moderate number (< 100) of complex types, each with a very small population, but with a high degree of connectivity amongst the complex types. Keywords: Signal transduction networks, Stochastic simulation, StochSim, Gillespie

  12. Top-Down CMOS-NEMS Polysilicon Nanowire with Piezoresistive Transduction

    PubMed Central

    Marigó, Eloi; Sansa, Marc; Pérez-Murano, Francesc; Uranga, Arantxa; Barniol, Núria

    2015-01-01

    A top-down clamped-clamped beam integrated in a CMOS technology with a cross section of 500 nm × 280 nm has been electrostatic actuated and sensed using two different transduction methods: capacitive and piezoresistive. The resonator made from a single polysilicon layer has a fundamental in-plane resonance at 27 MHz. Piezoresistive transduction avoids the effect of the parasitic capacitance assessing the capability to use it and enhance the CMOS-NEMS resonators towards more efficient oscillator. The displacement derived from the capacitive transduction allows to compute the gauge factor for the polysilicon material available in the CMOS technology. PMID:26184222

  13. Mixed-valent neptunium(IV/V) compound with cation-cation-bound six-membered neptunyl rings.

    PubMed

    Jin, Geng Bang

    2013-11-01

    A new mixed-valent neptunium(IV/V) compound has been synthesized by evaporation of a neptunium(V) acidic solution. The structure of the compound features cation-cation-bound six-membered neptunyl(V) rings. These rings are further connected by Np(IV) ions through cation-cation interactions (CCIs) into a three-dimensional neptunium cationic open framework. This example illustrates the possibility of isolating neptunyl(V) CCI oligomers in inorganic systems using other cations to compete with Np(V) in bonding with the neptunyl oxygen.

  14. Cation-cation interactions, magnetic communication and reactivity of the pentavalent uraniumion [U(NR)2]+

    SciTech Connect

    Spencer, Liam P; Schelter, Eric J; Boncella, James M; Yang, Ping; Gsula, Robyn L; Scott, Brian L; Thompson, Joe D; Kiplinger, Jacqueline L; Batista, Enrique R

    2009-01-01

    The dimeric bis(imido) uranium complex [{l_brace}U(NtBu)2(I)(tBu2bpy){r_brace}2] (see picture; U green, N blue, I red) has cation-cation interactions between [U(NR)2]+ ions. This f1-f1 system also displays f orbital communication between uranium(V) centers at low temperatures, and can be oxidized to generate uranium(VI) bis(imido) complexes.

  15. Sorption mechanism and predictive models for removal of cationic organic contaminants by cation exchange resins.

    PubMed

    Jadbabaei, Nastaran; Zhang, Huichun

    2014-12-16

    Understanding the sorption mechanism of organic contaminants on cation exchange resins (CXRs) will enable application of these resins for the removal of cationic organic compounds from contaminated water. In this study, sorption of a diverse set of 12 organic cations and 8 neutral aromatic solutes on two polystyrene CXRs, MN500 and Amberlite 200, was examined. MN500 showed higher sorbed concentrations due to its microporous structure. The sorbed concentrations followed the same trend of aromatic cations > aliphatic cations > neutral solutes for both resins. Generally, solute-solvent interactions, nonpolar moiety of the solutes, and resin matrix can affect selectivity of the cations. Sorbed concentrations of the neutral compounds were significantly less than those of the cations, indicating a combined effect of electrostatic and nonelectrostatic interactions. By conducting multiple linear regression between Gibbs free energy of sorption and Abraham descriptors for all 20 compounds, polarity/polarizability (S), H-bond acidity (A), induced dipole (E), and electrostatic (J(+)) interactions were found to be involved in the sorption of the cations by the resins. After converting the aqueous sorption isotherms to sorption from the ideal gas-phase by water-wet resins, a more significant effect of J(+) was observed. Predictive models were then developed based on the linear regressions and validated by accurately estimating the sorption of different test set compounds with a root-mean-square error range of 0.91-1.1 and 0.76-0.85 for MN500 and Amberlite 200, respectively. The models also accurately predicted sorption behavior of aniline and imidazole between pH 3 and 10. PMID:25409479

  16. Improving the alkaline stability of imidazolium cations by substitution.

    PubMed

    Dong, Huilong; Gu, Fenglou; Li, Min; Lin, Bencai; Si, Zhihong; Hou, Tingjun; Yan, Feng; Lee, Shuit-Tong; Li, Youyong

    2014-10-01

    Imidazolium cations are promising candidates for preparing anion-exchange membranes because of their good alkaline stability. Substitution of imidazolium cations is an efficient way to improve their alkaline stability. By combining density functional theory calculations with experimental results, it is found that the LUMO energy correlates with the alkaline stability of imidazolium cations. The results indicate that alkyl groups are the most suitable substituents for the N3 position of imidazolium cations, and the LUMO energies of alkyl-substituted imidazolium cations depend on the electron-donating effect and the hyperconjugation effect. Comparing 1,2-dimethylimidazolium cations (1,2-DMIm+) and 1,3-dimethylimidazolium cations (1,3-DMIm+) with the same substituents reveals that the hyperconjugation effect is more significant in influencing the LUMO energy of 1,3-DMIms. This investigation reveals that LUMO energy is a helpful aid in predicting the alkaline stability of imidazolium cations.

  17. Effect of supplementation with a lipid-based nutrient supplement on the micronutrient status of children aged 6–18 months living in the rural region of Intibucá, Honduras

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Lipid-based nutrient supplements (LNS) have been effective in the treatment of acute malnutrition among children. We evaluated the use of LNS supplementation for improving the micronutrient status of young children. Methods: A 12-month randomised controlled trial was conducted among chil...

  18. Lipid-based nutrient supplements do not affect the risk of malaria or respiratory morbidity in 6- to 18-month-old Malawian children in a randomized controlled trial

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is evidence to support the use of lipid-based nutrient supplements (LNSs) to promote child growth and development in low-income countries, but there is also a concern regarding the safety of using iron-fortified products in malaria-endemic areas. The objective of this study was to test the hyp...

  19. Antiretroviral therapy provided to HIV-infected Malawian women in a randomized trial diminishes the posiitive effect of lipid-based nutrient supplements on breast milk B-vitamins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: There is little information on B-vitamin concentrations in human milk or how they are affected by maternal B-vitamin deficiencies, antiretroviral (ARV) therapy or maternal supplementation. Objective: To evaluate effects of ARV therapy and/or lipid-based nutrient supplements (LNS) on B-v...

  20. Changes in gene expression and signal transduction in microgravity

    NASA Technical Reports Server (NTRS)

    Hughes-Fulford, M.

    2001-01-01

    Studies from space flights over the past three decades have demonstrated that basic physiological changes occur in humans during space flight. These changes include cephalic fluid shifts, loss of fluid and electrolytes, loss of muscle mass, space motion sickness, anemia, reduced immune response, and loss of calcium and mineralized bone. The cause of most of these manifestations is not known and until recently, the general approach was to investigate general systemic changes, not basic cellular responses to microgravity. This laboratory has recently studied gene growth and activation of normal osteoblasts (MC3T3-El) during spaceflight. Osteoblast cells were grown on glass coverslips and loaded in the Biorack plunger boxes. The osteoblasts were launched in a serum deprived state, activated in microgravity and collected in microgravity. The osteoblasts were examined for changes in gene expression and signal transduction. Approximately one day after growth activation significant changes were observed in gene expression in 0-G flight samples. Immediate early growth genes/growth factors cox-2, c-myc, bcl2, TGF beta1, bFGF and PCNA showed a significant diminished mRNA induction in microgravity FCS activated cells when compared to ground and 1-G flight controls. Cox-1 was not detected in any of the samples. There were no significant differences in the expression of reference gene mRNA between the ground, 0-G and 1-G samples. The data suggest that quiescent osteoblasts are slower to enter the cell cycle in microgravity and that the lack of gravity itself may be a significant factor in bone loss in spaceflight. Preliminary data from our STS 76 flight experiment support our hypothesis that a basic biological response occurs at the tissue, cellular, and molecular level in 0-G. Here we examine ground-based and space flown data to help us understand the mechanism of bone loss in microgravity.

  1. Biomechanical Origins of Muscle Stem Cell Signal Transduction.

    PubMed

    Morrissey, James B; Cheng, Richard Y; Davoudi, Sadegh; Gilbert, Penney M

    2016-04-10

    Skeletal muscle, the most abundant and widespread tissue in the human body, contracts upon receiving electrochemical signals from the nervous system to support essential functions such as thermoregulation, limb movement, blinking, swallowing and breathing. Reconstruction of adult muscle tissue relies on a pool of mononucleate, resident muscle stem cells, known as "satellite cells", expressing the paired-box transcription factor Pax7 necessary for their specification during embryonic development and long-term maintenance during adult life. Satellite cells are located around the myofibres in a niche at the interface of the basal lamina and the host fibre plasma membrane (i.e., sarcolemma), at a very low frequency. Upon damage to the myofibres, quiescent satellite cells are activated and give rise to a population of transient amplifying myogenic progenitor cells, which eventually exit the cell cycle permanently and fuse to form new myofibres and regenerate the tissue. A subpopulation of satellite cells self-renew and repopulate the niche, poised to respond to future demands. Harnessing the potential of satellite cells relies on a complete understanding of the molecular mechanisms guiding their regulation in vivo. Over the past several decades, studies revealed many signal transduction pathways responsible for satellite cell fate decisions, but the niche cues driving the activation and silencing of these pathways are less clear. Here we explore the scintillating possibility that considering the dynamic changes in the biophysical properties of the skeletal muscle, namely stiffness, and the stretch and shear forces to which a myofibre can be subjected to may provide missing information necessary to gain a full understanding of satellite cell niche regulation. PMID:26004541

  2. Second-Chance Signal Transduction Explains Cooperative Flagellar Switching

    PubMed Central

    Zot, Henry G.; Hasbun, Javier E.; Van Minh, Nguyen

    2012-01-01

    The reversal of flagellar motion (switching) results from the interaction between a switch complex of the flagellar rotor and a torque-generating stationary unit, or stator (motor unit). To explain the steeply cooperative ligand-induced switching, present models propose allosteric interactions between subunits of the rotor, but do not address the possibility of a reaction that stimulates a bidirectional motor unit to reverse direction of torque. During flagellar motion, the binding of a ligand-bound switch complex at the dwell site could excite a motor unit. The probability that another switch complex of the rotor, moving according to steady-state rotation, will reach the same dwell site before that motor unit returns to ground state will be determined by the independent decay rate of the excited-state motor unit. Here, we derive an analytical expression for the energy coupling between a switch complex and a motor unit of the stator complex of a flagellum, and demonstrate that this model accounts for the cooperative switching response without the need for allosteric interactions. The analytical result can be reproduced by simulation when (1) the motion of the rotor delivers a subsequent ligand-bound switch to the excited motor unit, thereby providing the excited motor unit with a second chance to remain excited, and (2) the outputs from multiple independent motor units are constrained to a single all-or-none event. In this proposed model, a motor unit and switch complex represent the components of a mathematically defined signal transduction mechanism in which energy coupling is driven by steady-state and is regulated by stochastic ligand binding. Mathematical derivation of the model shows the analytical function to be a general form of the Hill equation (Hill AV (1910) The possible effects of the aggregation of the molecules of haemoglobin on its dissociation curves. J Physiol 40: iv–vii). PMID:22844429

  3. Signal Transduction by BvgS Sensor Kinase

    PubMed Central

    Dupré, Elian; Lesne, Elodie; Guérin, Jérémy; Lensink, Marc F.; Verger, Alexis; de Ruyck, Jérôme; Brysbaert, Guillaume; Vezin, Hervé; Locht, Camille; Antoine, Rudy; Jacob-Dubuisson, Françoise

    2015-01-01

    The two-component sensory transduction system BvgAS controls the virulence regulon of the whooping-cough agent Bordetella pertussis. The periplasmic moiety of the homodimeric sensor kinase BvgS is composed of four bilobed Venus flytrap (VFT) perception domains followed by α helices that extend into the cytoplasmic membrane. In the virulent phase, the default state of B. pertussis, the cytoplasmic enzymatic moiety of BvgS acts as kinase by autophosphorylating and transferring the phosphoryl group to the response regulator BvgA. Under laboratory conditions, BvgS shifts to phosphatase activity in response to modulators, notably nicotinate ions. Here we characterized the effects of nicotinate and related modulators on the BvgS periplasmic moiety by using site-directed mutagenesis and in silico and biophysical approaches. Modulators bind with low affinity to BvgS in the VFT2 cavity. Electron paramagnetic resonance shows that their binding globally affects the conformation and dynamics of the periplasmic moiety. Specific amino acid substitutions designed to slacken interactions within and between the VFT lobes prevent BvgS from responding to nicotinate, showing that BvgS shifts from kinase to phosphatase activity in response to this modulator via a tense transition state that involves a large periplasmic structural block. We propose that this transition enables the transmembrane helices to adopt a distinct conformation that sets the cytoplasmic enzymatic moiety in the phosphatase mode. The bona fide, in vivo VFT ligands that remain to be identified are likely to trigger similar effects on the transmembrane and cytoplasmic moieties. This mechanism may be relevant to the other VFT-containing sensor kinases homologous to BvgS. PMID:26203186

  4. Matricellular signal transduction involving calmodulin in the social amoebozoan dictyostelium.

    PubMed

    O'Day, Danton H; Huber, Robert J

    2013-01-01

    The social amoebozoan Dictyostelium discoideum undergoes a developmental sequence wherein an extracellular matrix (ECM) sheath surrounds a group of differentiating cells. This sheath is comprised of proteins and carbohydrates, like the ECM of mammalian tissues. One of the characterized ECM proteins is the cysteine-rich, EGF-like (EGFL) repeat-containing, calmodulin (CaM)-binding protein (CaMBP) CyrA. The first EGFL repeat of CyrA increases the rate of random cell motility and cyclic AMP-mediated chemotaxis. Processing of full-length CyrA (~63 kDa) releases two major EGFL repeat-containing fragments (~45 kDa and ~40 kDa) in an event that is developmentally regulated. Evidence for an EGFL repeat receptor also exists and downstream intracellular signaling pathways involving CaM, Ras, protein kinase A and vinculin B phosphorylation have been characterized. In total, these results identify CyrA as a true matricellular protein comparable in function to tenascin C and other matricellular proteins from mammalian cells. Insight into the regulation and processing of CyrA has also been revealed. CyrA is the first identified extracellular CaMBP in this eukaryotic microbe. In keeping with this, extracellular CaM (extCaM) has been shown to be present in the ECM sheath where it binds to CyrA and inhibits its cleavage to release the 45 kDa and 40 kDa EGFL repeat-containing fragments. The presence of extCaM and its role in regulating a matricellular protein during morphogenesis extends our understanding of CaM-mediated signal transduction in eukaryotes. PMID:24705101

  5. New insights into transduction pathways that regulate boar sperm function.

    PubMed

    Hurtado de Llera, A; Martin-Hidalgo, D; Gil, M C; Garcia-Marin, L J; Bragado, M J

    2016-01-01

    Detailed molecular mechanisms mediating signal transduction cascades that regulate boar sperm function involving Ser/Thr and tyrosine phosphorylation of proteins have been reviewed previously. Therefore, this review will focus in those kinase pathways identified recently (<10 years) in boar spermatozoa that regulate different functional spermatozoa processes. AMP-activated protein kinase (AMPK) is a cell energy sensor kinase that was first identified in mammalian spermatozoa in 2012, and since then it has emerged as an essential regulator of boar sperm function. Signaling pathways leading to AMPK activation in boar sperm are highlighted in this review (PKA, CaMKKα/β, and PKC as well as Ca(2+) and cAMP messengers as upstream regulators). Interestingly, stimuli considered as cell stress (hyperosmotic stress, inhibition of mitochondrial activity, absence of intracellular Ca(2+)) markedly activate AMPK in boar spermatozoa. Moreover, AMPK plays a remarkable and necessary regulatory role in mammalian sperm function, controlling essential boar sperm functional processes such as motility, viability, mitochondrial membrane potential, organization and fluidity of plasma membrane, and outer acrosome membrane integrity. These mentioned processes are all required under fluctuating environment of spermatozoa when transiting through the female reproductive tract to achieve fertilization. An applied role of AMPK in artificial insemination techniques is also suggested as during boar seminal doses preservation at 17 °C, physiological levels of AMPK activity markedly increase (maximum on Day 7) and result essential to maintain the aforementioned fundamental sperm processes. Moreover, regulation of sperm function exerted by the glycogen synthase kinase 3 and Src family kinase pathways is summarized.

  6. Transduction-like gene transfer in the methanogen Methanococcus voltae

    NASA Technical Reports Server (NTRS)

    Bertani, G.

    1999-01-01

    Strain PS of Methanococcus voltae (a methanogenic, anaerobic archaebacterium) was shown to generate spontaneously 4.4-kbp chromosomal DNA fragments that are fully protected from DNase and that, upon contact with a cell, transform it genetically. This activity, here called VTA (voltae transfer agent), affects all markers tested: three different auxotrophies (histidine, purine, and cobalamin) and resistance to BES (2-bromoethanesulfonate, an inhibitor of methanogenesis). VTA was most effectively prepared by culture filtration. This process disrupted a fraction of the M. voltae cells (which have only an S-layer covering their cytoplasmic membrane). VTA was rapidly inactivated upon storage. VTA particles were present in cultures at concentrations of approximately two per cell. Gene transfer activity varied from a minimum of 2 x 10(-5) (BES resistance) to a maximum of 10(-3) (histidine independence) per donor cell. Very little VTA was found free in culture supernatants. The phenomenon is functionally similar to generalized transduction, but there is no evidence, for the time being, of intrinsically viral (i.e., containing a complete viral genome) particles. Consideration of VTA DNA size makes the existence of such viral particles unlikely. If they exist, they must be relatively few in number;perhaps they differ from VTA particles in size and other properties and thus escaped detection. Digestion of VTA DNA with the AluI restriction enzyme suggests that it is a random sample of the bacterial DNA, except for a 0.9-kbp sequence which is amplified relative to the rest of the bacterial chromosome. A VTA-sized DNA fraction was demonstrated in a few other isolates of M. voltae.

  7. Matricellular signal transduction involving calmodulin in the social amoebozoan dictyostelium.

    PubMed

    O'Day, Danton H; Huber, Robert J

    2013-02-15

    The social amoebozoan Dictyostelium discoideum undergoes a developmental sequence wherein an extracellular matrix (ECM) sheath surrounds a group of differentiating cells. This sheath is comprised of proteins and carbohydrates, like the ECM of mammalian tissues. One of the characterized ECM proteins is the cysteine-rich, EGF-like (EGFL) repeat-containing, calmodulin (CaM)-binding protein (CaMBP) CyrA. The first EGFL repeat of CyrA increases the rate of random cell motility and cyclic AMP-mediated chemotaxis. Processing of full-length CyrA (~63 kDa) releases two major EGFL repeat-containing fragments (~45 kDa and ~40 kDa) in an event that is developmentally regulated. Evidence for an EGFL repeat receptor also exists and downstream intracellular signaling pathways involving CaM, Ras, protein kinase A and vinculin B phosphorylation have been characterized. In total, these results identify CyrA as a true matricellular protein comparable in function to tenascin C and other matricellular proteins from mammalian cells. Insight into the regulation and processing of CyrA has also been revealed. CyrA is the first identified extracellular CaMBP in this eukaryotic microbe. In keeping with this, extracellular CaM (extCaM) has been shown to be present in the ECM sheath where it binds to CyrA and inhibits its cleavage to release the 45 kDa and 40 kDa EGFL repeat-containing fragments. The presence of extCaM and its role in regulating a matricellular protein during morphogenesis extends our understanding of CaM-mediated signal transduction in eukaryotes.

  8. Signal transduction through the IL-4 and insulin receptor families.

    PubMed

    Wang, L M; Keegan, A; Frankel, M; Paul, W E; Pierce, J H

    1995-07-01

    Activation of tyrosine kinase-containing receptors and intracellular tyrosine kinases by ligand stimulation is known to be crucial for mediating initial and subsequent events involved in mitogenic signal transduction. Receptors for insulin and insulin-like growth factor 1 (IGF-1) contain cytoplasmic tyrosine kinase domains that undergo autophosphorylation upon ligand stimulation. Activation of these receptors also leads to pronounced and rapid tyrosine phosphorylation of insulin receptor substrate 1 (IRS-1) in cells of connective tissue origin. A related substrate, designated 4PS, is similarly phosphorylated by insulin and IGF-1 stimulation in many hematopoietic cell types. IRS-1 and 4PS possess a number of tyrosine phosphorylation sites that are within motifs that bind specific SH2-containing molecules known to be involved in mitogenic signaling such as PI-3 kinase, SHPTP-2 (Syp) and Grb-2. Thus, they appear to act as docking substrates for a variety of signaling molecules. The majority of hematopoietic cytokines bind to receptors that do not possess intrinsic kinase activity, and these receptors have been collectively termed as members of the hematopoietin receptor superfamily. Despite their lack of tyrosine kinase domains, stimulation of these receptors has been demonstrated to activate intracellular kinases leading to tyrosine phosphorylation of multiple substrates. Recent evidence has demonstrated that activation of different members of the Janus family of tyrosine kinases is involved in mediating tyrosine phosphorylation events by specific cytokines. Stimulation of the interleukin 4 (IL-4) receptor, a member of the hematopoietin receptor superfamily, is thought to result in activation of Jak1, Jak3, and/or Fes tyrosine kinases.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Transduction of plasmid DNA in Streptomyces spp. and related genera by bacteriophage FP43.

    PubMed

    McHenney, M A; Baltz, R H

    1988-05-01

    A segment (hft) of bacteriophage FP43 DNA cloned into plasmid pIJ702 mediated high-frequency transduction of the resulting plasmid (pRHB101) by FP43 in Streptomyces griseofuscus. The transducing particles contained linear concatemers of plasmid DNA. Lysates of FP43 prepared on S. griseofuscus containing pRHB101 also transduced many other Streptomyces species, including several that restrict plaque formation by FP43 and at least two that produce restriction endonucleases that cut pRHB101 DNA. Transduction efficiencies in different species were influenced by the addition of anti-FP43 antiserum to the transduction plates, the temperature for cell growth before transduction, the multiplicity of infection, and the host on which the transducing lysate was prepared. FP43 lysates prepared on S. griseofuscus(pRHB101) also transduced species of Streptoverticillium, Chainia, and Saccharopolyspora.

  10. Comparison of LNS-AmB, a novel low-dose formulation of amphotericin B with lipid nano-sphere (LNS), with commercial lipid-based formulations.

    PubMed

    Fukui, Hiroshi; Koike, Tomohiro; Nakagawa, Takashi; Saheki, Akira; Sonoke, Satoru; Tomii, Yoshifumi; Seki, Junzo

    2003-11-28

    Three lipid-based delivery systems (AmBisome, Amphocil, and Abelcet) for amphotericin B (AmB) have been marketed to overcome the disadvantages associated with the clinical use of AmB. However, to show their efficacy, they need to be administered at higher doses than the conventional dosage form, Fungizone. In this study, we compared LNS-AmB, our new low-dose therapeutic system for AmB using lipid nano-sphere (LNS), with these commercial formulations in terms of their pharmacokinetics and efficacy. The plasma AmB levels yielded by LNS-AmB after intravenous administration to rats were much higher than those yielded by Amphocil or Abelcet, and similar to those yielded by AmBisome, but in dogs LNS-AmB yielded plasma AmB concentrations about three times higher than did AmBisome. In a carrageenin-induced pleurisy model in rats, LNS-AmB yielded AmB levels in the pleural exudate over 20 times those yielded by Amphocil or Abelcet, and similar to those yielded by AmBisome. From these pharmacokinetic results, it is clear that Amphocil and Abelcet are based on a quite distinct drug-delivery concept from LNS-AmB. In a rat model of localized candidiasis, LNS-AmB significantly inhibited the growth of Candida albicans in the pouch, whereas AmBisome did not, even though the AmB concentrations in the pouch were similar. This difference in antifungal activity between LNS-AmB and AmBisome was also found in vitro. That is, the antifungal activity of LNS-AmB against C. albicans was similar to that of Fungizone and dimethyl sulfoxide-solubilized AmB, while AmBisome showed weaker antifungal activity than did other formulations. Based on these results, the release of AmB from AmBisome was judged to be slow and slight. In a mouse model of systemic candidiasis, LNS-AmB (1.0mg/kg) was much more effective than AmBisome (8.0mg/kg) or Fungizone (1.0mg/kg). These results suggest that LNS-AmB maintained the potent activity of AmB against fungal cells even though the AmB was incorporated into LNS

  11. [PAH Cations as Viable Carriers of DIBs

    NASA Technical Reports Server (NTRS)

    Snow, Ted

    1998-01-01

    This report is intended to fill in the blanks in NASA's file system for our lab astro study of molecular ions of astrophysical interest. In order to give NASA what it needs for its files, I attach below the text of the section from our recent proposal to continue this work, in which we describe progress to date, including a large number of publications. Our initial studies were focused on PAH cations, which appear to be viable candidates as the carriers of the DIBs, an idea that has been supported by laboratory spectroscopy of PAH cations in inert matrices. Beginning with the simplest aromatic (benzene; C6H6) and moving progressively to larger species (naphthalene, C10OH8; pyrene, C16H10; and most recently chrysene, C18H12), we have been able to derive rate coefficients for reactions with neutral spices that are abundant in the diffuse interstellar medium.

  12. Electronic spectrum of 9-methylanthracenium radical cation

    NASA Astrophysics Data System (ADS)

    O'Connor, Gerard D.; Sanelli, Julian A.; Dryza, Vik; Bieske, Evan J.; Schmidt, Timothy W.

    2016-04-01

    The predissociation spectrum of the cold, argon-tagged, 9-methylanthracenium radical cation is reported from 8000 cm-1 to 44 500 cm-1. The reported spectrum contains bands corresponding to at least eight electronic transitions ranging from the near infrared to the ultraviolet. These electronic transitions are assigned through comparison with ab initio energies and intensities. The infrared D1←D0 transitions exhibit significant vibronic activity, which is assigned through comparison with TD-B3LYP excited state frequencies and intensities, as well as modelled vibronic interactions. Dissociation of 9-methylanthracenium is also observed at high visible-photon energies, resulting in the loss of either CH2 or CH3. The relevance of these spectra, and the spectra of other polycyclic aromatic hydrocarbon radical cations, to the largely unassigned diffuse interstellar bands, is discussed.

  13. The psychobiology of mind-body communication: the complex, self-organizing field of information transduction.

    PubMed

    Rossi, E L

    1996-01-01

    The current information revolution in molecular biology has important implications for an new understanding of the phenomenology of mind, memory and behavior as a complex, self-organizing field of information transduction. This paper traces the pathways of information transduction in life processes from the molecular-genetic level to the dynamics of mind and behavior together with suggestions for future research exploring the psychobiology of mind-body communication and its implications for the psychotherapeutic arts of the future.

  14. Alkaline earth cation extraction from acid solution

    DOEpatents

    Dietz, Mark; Horwitz, E. Philip

    2003-01-01

    An extractant medium for extracting alkaline earth cations from an aqueous acidic sample solution is described as are a method and apparatus for using the same. The separation medium is free of diluent, free-flowing and particulate, and comprises a Crown ether that is a 4,4'(5')[C.sub.4 -C.sub.8 -alkylcyclohexano]18-Crown-6 dispersed on an inert substrate material.

  15. Sn Cation Valency Dependence in Cation Exchange Reactions Involving Cu2-xSe Nanocrystals

    PubMed Central

    2014-01-01

    We studied cation exchange reactions in colloidal Cu2-xSe nanocrystals (NCs) involving the replacement of Cu+ cations with either Sn2+ or Sn4+ cations. This is a model system in several aspects: first, the +2 and +4 oxidation states for tin are relatively stable; in addition, the phase of the Cu2-xSe NCs remains cubic regardless of the degree of copper deficiency (that is, “x”) in the NC lattice. Also, Sn4+ ions are comparable in size to the Cu+ ions, while Sn2+ ones are much larger. We show here that the valency of the entering Sn ions dictates the structure and composition not only of the final products but also of the intermediate steps of the exchange. When Sn4+ cations are used, alloyed Cu2–4ySnySe NCs (with y ≤ 0.33) are formed as intermediates, with almost no distortion of the anion framework, apart from a small contraction. In this exchange reaction the final stoichiometry of the NCs cannot go beyond Cu0.66Sn0.33Se (that is Cu2SnSe3), as any further replacement of Cu+ cations with Sn4+ cations would require a drastic reorganization of the anion framework, which is not possible at the reaction conditions of the experiments. When instead Sn2+ cations are employed, SnSe NCs are formed, mostly in the orthorhombic phase, with significant, albeit not drastic, distortion of the anion framework. Intermediate steps in this exchange reaction are represented by Janus-type Cu2-xSe/SnSe heterostructures, with no Cu–Sn–Se alloys. PMID:25340627

  16. Low Cation Coordination in Oxide Melts

    NASA Astrophysics Data System (ADS)

    Skinner, L. B.; Benmore, C. J.; Weber, J. K. R.; Du, J.; Neuefeind, J.; Tumber, S. K.; Parise, J. B.

    2014-04-01

    The complete set of partial pair distribution functions for a rare earth oxide liquid are measured by combining aerodynamic levitation, neutron and x-ray diffraction on Y2O3, and Ho2O3 melts at 2870 K. The average Y-O (or Ho-O) coordination of these isomorphic melts is measured to be 5.5(2), which is significantly less than the octahedral coordination of crystalline Y2O3 (or Ho2O3). Investigation of La2O3, ZrO2, and Al2O3 melts by x-ray diffraction and molecular dynamics simulations also show lower-than-crystal cation-oxygen coordination. These measurements suggest a general trend towards lower coordination compared to their crystalline counterparts. It is found that the coordination drop is larger for lower field strength, larger radius cations and is negligible for high field strength (network forming) cations, such as SiO2. These findings have broad implications for predicting the local structure and related physical properties of metal-oxide melts and oxide glasses.

  17. Low cation coordination in oxide melts.

    PubMed

    Skinner, L B; Benmore, C J; Weber, J K R; Du, J; Neuefeind, J; Tumber, S K; Parise, J B

    2014-04-18

    The complete set of partial pair distribution functions for a rare earth oxide liquid are measured by combining aerodynamic levitation, neutron and x-ray diffraction on Y2O3, and Ho2O3 melts at 2870 K. The average Y-O (or Ho-O) coordination of these isomorphic melts is measured to be 5.5(2), which is significantly less than the octahedral coordination of crystalline Y2O3 (or Ho2O3). Investigation of La2O3, ZrO2, and Al2O3 melts by x-ray diffraction and molecular dynamics simulations also show lower-than-crystal cation-oxygen coordination. These measurements suggest a general trend towards lower coordination compared to their crystalline counterparts. It is found that the coordination drop is larger for lower field strength, larger radius cations and is negligible for high field strength (network forming) cations, such as SiO2. These findings have broad implications for predicting the local structure and related physical properties of metal-oxide melts and oxide glasses. PMID:24785072

  18. Low cation coordination in oxide melts

    SciTech Connect

    Skinner, Lawrie; Benmore, Chris J; Du, Jincheng; Weber, Richard; Neuefeind, Joerg C; Tumber, Sonia; Parise, John B

    2014-01-01

    The complete set of Faber-Ziman partial pair distribution functions for a rare earth oxide liquid were measured for the first time by combining aerodynamic levitation, neutron diffraction, high energy x-ray diffraction and isomorphic substitution using Y2 O3 and Ho2 O3 melts. The average Y- O coordination is measured to be 5.5(2), which is significantly less than the octahedral coordination of crystalline Y2 O3 (or Ho2 O3 ). Investigation of high temperature La2 O3 , ZrO2 , SiO2 , and Al2 O3 melts by x-ray diffraction and molecular dynamics simulations also show lower-than-crystal cation- oxygen coordination. These measurements suggest a general trend towards lower M-O coordination compared to their crystalline counterparts. It is found that this coordination number drop is larger for lower field strength, larger radius cations and is negligible for high field strength (network forming) cations. These findings have broad implications for predicting the local structure and related physical properties of metal-oxide melts and oxide glasses.

  19. Enhancement of deoxyribozyme activity by cationic copolymers.

    PubMed

    Gao, Jueyuan; Shimada, Naohiko; Maruyama, Atsushi

    2015-02-01

    Deoxyribozymes, or DNAzymes, are DNA molecules with enzymatic activity. DNAzymes with ribonuclease activity have various potential applications in biomedical and bioanalytical fields; however, most constructs have limited turnover despite optimization of reaction conditions and DNAzyme structures. A cationic comb-type copolymer accelerates DNA hybridization and strand exchange rates, and we hypothesized that the copolymer would enhance deoxyribozyme activity by promoting turnover. The copolymer did not change DNAzyme activity under single-turnover conditions, suggesting that the copolymer affects neither the folding structure of DNAzyme nor the association of a divalent cation, a catalytic cofactor, to DNAzyme. The copolymer enhanced activity of the evaluated DNAzyme over a wide temperature range under multiple-turnover conditions. The copolymer increased the DNAzyme kcat/KM by fifty-fold at 50 °C, the optimal temperature for the DNAzyme in the absence of the copolymer. The acceleration effect was most significant when the reaction temperature was slightly higher than the melting temperature of the enzyme/substrate complex; acceleration of two orders of magnitude was observed. We concluded that the copolymer accelerated the turnover step without influencing the chemical cleavage step. In contrast to the copolymer, a cationic surfactant, CTAB, strongly inhibited the DNAzyme activity under either single- or multiple-turnover conditions. PMID:26218121

  20. Polybrene: Observations on cochlear hair cell necrosis and minimal lentiviral transduction of cochlear hair cells.

    PubMed

    Han, Miaomiao; Yu, Dongzhen; Song, Qiang; Wang, Jiping; Dong, Pin; He, Jingchun

    2015-07-23

    Polybrene is widely used to enhance viral transduction; however, little is known about the utility thereof, in enhancing lentiviral transduction of cochlear cells. In the present study, we examined the cytotoxic effects of polybrene, and the further effects thereof, on lentiviral transduction of cochlear cells, especially sensory hair cells. Cochlear basilar membranes of newborn rats were cultured and treated with 0.1-10 μg/mL polybrene for 24h to explore the potential development of ototoxicity. PI staining and TUNEL detection were used to evaluate necrosis or apoptosis of hair cell. Various doses of lentivirus-GFP were added to cochlear organotypic cultures with safe concentrations of polybrene, incubated for 24h, and cultured (in the absence of the virus and polybrene) for a further 48 h. Transduction efficiencies were evaluated. The results showed that polybrene at 0.1 μg/mL was safe to cochlear cells, and 0.5-10 μg/mL concentration induced hair cell necrosis in a dose-dependent manner. However, supporting cells were not damaged. Lentiviral vectors transduced into cochlear cells and 0.1 μg/mL polybrene enhanced transduction efficiency. However, hair cells were hardly transduced with lentiviral vectors either alone or in the presence of 0.1 μg/mL polybrene. The use of polybrene to aid lentiviral transduction of cochlear hair cells requires further attention.

  1. Polybrene: Observations on cochlear hair cell necrosis and minimal lentiviral transduction of cochlear hair cells.

    PubMed

    Han, Miaomiao; Yu, Dongzhen; Song, Qiang; Wang, Jiping; Dong, Pin; He, Jingchun

    2015-07-23

    Polybrene is widely used to enhance viral transduction; however, little is known about the utility thereof, in enhancing lentiviral transduction of cochlear cells. In the present study, we examined the cytotoxic effects of polybrene, and the further effects thereof, on lentiviral transduction of cochlear cells, especially sensory hair cells. Cochlear basilar membranes of newborn rats were cultured and treated with 0.1-10 μg/mL polybrene for 24h to explore the potential development of ototoxicity. PI staining and TUNEL detection were used to evaluate necrosis or apoptosis of hair cell. Various doses of lentivirus-GFP were added to cochlear organotypic cultures with safe concentrations of polybrene, incubated for 24h, and cultured (in the absence of the virus and polybrene) for a further 48 h. Transduction efficiencies were evaluated. The results showed that polybrene at 0.1 μg/mL was safe to cochlear cells, and 0.5-10 μg/mL concentration induced hair cell necrosis in a dose-dependent manner. However, supporting cells were not damaged. Lentiviral vectors transduced into cochlear cells and 0.1 μg/mL polybrene enhanced transduction efficiency. However, hair cells were hardly transduced with lentiviral vectors either alone or in the presence of 0.1 μg/mL polybrene. The use of polybrene to aid lentiviral transduction of cochlear hair cells requires further attention. PMID:26071903

  2. Transduction of staphylococcal cassette chromosome mec elements between strains of Staphylococcus aureus.

    PubMed

    Scharn, Caitlyn R; Tenover, Fred C; Goering, Richard V

    2013-11-01

    Methicillin-resistant Staphylococcus aureus (MRSA) is a well-known public health concern. However, the means by which methicillin resistance genes are transferred among staphylococci in nature remains unknown. Older scientific literature suggests transduction as a means of mecA transfer, but the optimal conditions are reported to require plasmids and potentially a lysogenic phage. These reports preceded discovery of the staphylococcal cassette chromosome mec (SCCmec) elements. We undertook studies to confirm and clarify the conditions promoting transduction of SCCmec in S. aureus populations using well-characterized donor and recipient strains primarily of the USA300 lineage. Both bacteriophages 80α and 29 were capable of transducing SCCmec type IV and SCCmec type I to recipient strains of S. aureus. Pulsed-field gel electrophoresis and mec-associated dru typing were used to confirm the identity of the transductants. Transfer of mecA via transduction occurred at low frequency and required extended selection times for mecA gene expression and the presence of a penicillinase plasmid in the recipient. However, interference with the process by clavulanic acid and the necessity of lysogeny with 11 in the recipient or the presence of a small (4-kb) tetracycline resistance plasmid, as previously reported, were not confirmed. SCCmec transduction was occasionally associated with substantial deletions or truncation of SCCmec and the arginine catabolic metabolic element in USA300 recipients. Overall, these data clarify the conditions required for SCCmec transduction and document that rearrangements may occur during the process. PMID:23939891

  3. Evidence that membrane transduction of oligoarginine does not require vesicle formation

    SciTech Connect

    Zaro, Jennica L.; Shen Weichiang . E-mail: weishen@usc.edu

    2005-07-01

    The involvement of vesicular formation processes in the membrane transduction and nuclear transport of oligoarginine is currently a subject of controversy. In this report, a novel quantitative method which allows for the selective measurement of membrane transduction excluding concurrent endocytosis was used to determine the effects of temperature, endosomal acidification, endosomolysis, and several known inhibitors of endocytic pathways on the internalization of oligoarginine. The results show that, unlike endocytosis, transduction of oligoarginine was not affected by incubation at 16 deg. C as compared to the 37 deg. C control, and was only partially inhibited at 4 deg. C incubation. Additionally, membrane transduction was not inhibited to the same extent as endocytosis following treatment with ammonium chloride, hypertonic medium, amiloride, or filipin. The endosomolytic activity of oligoarginine was investigated by examining the leakage of FITC-dextran into the cytosolic compartment, which was not higher in the presence of oligoarginine. Furthermore, ammonium chloride showed no effect on the nuclear transport of oligoarginine. The data presented in this report indicate that membrane transduction is likely to occur at the plasma membrane without the formation of membrane vesicles, and the nuclear localization involves membrane transduction, rather than endocytosis of oligoarginine.

  4. Transduction of Methicillin Resistance in Staphylococcus aureus Dependent on an Unusual Specificity of the Recipient Strain

    PubMed Central

    Cohen, Sidney; Sweeney, Helen M.

    1970-01-01

    Resistance to methicillin was transduced by phage 80 or 53 from two naturally occurring methicillin-resistant strains of Staphylococcus aureus to methicillin-susceptible recipient strains at frequencies of 10−7 to 10−9. Ultraviolet irradiation of transducing phage and posttransductional incubation at 30 C were essential for useful frequencies of transduction. Effectiveness as a recipient for this transduction was highly specific. Strain NCTC 8325 (PS47) in its native state was an ineffective recipient but became effective after it had received by transduction one of several penicillinase plasmids. This acquired effectiveness was retained in most cases after elimination of the plasmid by ethidium bromide treatment. Like the donor strain, the progeny were heterogeneous in the degree of their resistance to methicillin, which was expressed by a higher proportion of cells as the temperature of incubation was lowered from 37 to 30 C. Separate transductants varied widely in the degree of resistance acquired by transduction. Methicillin resistance was stable in the donor and transductant strains. We favored the interpretation that methicillin resistance in our strains was determined by a single chromosomal gene, although the possibility that it was determined by two or more closely linked genes could not be excluded. PMID:16559089

  5. Sentra : a database of signal transduction proteins for comparative genome analysis.

    SciTech Connect

    D'Souza, M.; Glass, E. M.; Syed, M. H.; Zhang, Y.; Rodriguez, A.; Maltsev, N.; Galerpin, M. Y.; Mathematics and Computer Science; Univ. of Chicago; NIH

    2007-01-01

    Sentra (http://compbio.mcs.anl.gov/sentra), a database of signal transduction proteins encoded in completely sequenced prokaryotic genomes, has been updated to reflect recent advances in understanding signal transduction events on a whole-genome scale. Sentra consists of two principal components, a manually curated list of signal transduction proteins in 202 completely sequenced prokaryotic genomes and an automatically generated listing of predicted signaling proteins in 235 sequenced genomes that are awaiting manual curation. In addition to two-component histidine kinases and response regulators, the database now lists manually curated Ser/Thr/Tyr protein kinases and protein phosphatases, as well as adenylate and diguanylate cyclases and c-di-GMP phosphodiesterases, as defined in several recent reviews. All entries in Sentra are extensively annotated with relevant information from public databases (e.g. UniProt, KEGG, PDB and NCBI). Sentra's infrastructure was redesigned to support interactive cross-genome comparisons of signal transduction capabilities of prokaryotic organisms from a taxonomic and phenotypic perspective and in the framework of signal transduction pathways from KEGG. Sentra leverages the PUMA2 system to support interactive analysis and annotation of signal transduction proteins by the users.

  6. Polyploidization without mitosis improves in vivo liver transduction with lentiviral vectors.

    PubMed

    Pichard, Virginie; Couton, Dominique; Desdouets, Chantal; Ferry, Nicolas

    2013-02-01

    Lentiviral vectors are efficient gene delivery vehicles for therapeutic and research applications. In contrast to oncoretroviral vectors, they are able to infect most nonproliferating cells. In the liver, induction of cell proliferation dramatically improved hepatocyte transduction using all types of retroviral vectors. However, the precise relationship between hepatocyte division and transduction efficiency has not been determined yet. Here we compared gene transfer efficiency in the liver after in vivo injection of recombinant lentiviral or Moloney murine leukemia viral (MoMuLV) vectors in hepatectomized rats treated or not with retrorsine, an alkaloid that blocks hepatocyte division and induces megalocytosis. Partial hepatectomy alone resulted in a similar increase in hepatocyte transduction using either vector. In retrorsine-treated and partially hepatectomized rats, transduction with MoMuLV vectors dropped dramatically. In contrast, we observed that retrorsine treatment combined with partial hepatectomy increased lentiviral transduction to higher levels than hepatectomy alone. Analysis of nuclear ploidy in single cells showed that a high level of transduction was associated with polyploidization. In conclusion, endoreplication could be exploited to improve the efficiency of liver-directed lentiviral gene therapy.

  7. Amiloride-Insensitive Salt Taste Is Mediated by Two Populations of Type III Taste Cells with Distinct Transduction Mechanisms

    PubMed Central

    Sukumaran, Sunil K.; Margolskee, Robert F.; Bachmanov, Alexander A.

    2016-01-01

    Responses in the amiloride-insensitive (AI) pathway, one of the two pathways mediating salty taste in mammals, are modulated by the size of the anion of a salt. This “anion effect” has been hypothesized to result from inhibitory transepithelial potentials (TPs) generated across the lingual epithelium as cations permeate through tight junctions and leave their larger and less permeable anions behind (Ye et al., 1991). We tested directly the necessity of TPs for the anion effect by measuring responses to NaCl and Na-gluconate (small and large anion sodium salts, respectively) in isolated taste cells from mouse circumvallate papillae. Using calcium imaging, we identified AI salt-responsive type III taste cells and demonstrated that they compose a subpopulation of acid-responsive taste cells. Even in the absence of TPs, many (66%) AI salt-responsive type III taste cells still exhibited the anion effect, demonstrating that some component of the transduction machinery for salty taste in type III cells is sensitive to anion size. We hypothesized that osmotic responses could explain why a minority of type III cells (34%) had AI salt responses but lacked anion sensitivity. All AI type III cells had osmotic responses to cellobiose, which were significantly modulated by extracellular sodium concentration, suggesting the presence of a sodium-conducting osmotically sensitive ion channel. However, these responses were significantly larger in AI type III cells that did not exhibit the anion effect. These findings indicate that multiple mechanisms could underlie AI salt responses in type III taste cells, one of which may contribute to the anion effect. SIGNIFICANCE STATEMENT Understanding the mechanisms underlying salty taste will help inform strategies to combat the health problems associated with NaCl overconsumption by humans. Of the two pathways underlying salty taste in mammals, the amiloride-insensitive (AI) pathway is the least understood. Using calcium imaging of

  8. Alkali cation specific adsorption onto fcc(111) transition metal electrodes.

    PubMed

    Mills, J N; McCrum, I T; Janik, M J

    2014-07-21

    The presence of alkali cations in electrolyte solutions is known to impact the rate of electrocatalytic reactions, though the mechanism of such impact is not conclusively determined. We use density functional theory (DFT) to examine the specific adsorption of alkali cations to fcc(111) electrode surfaces, as specific adsorption may block catalyst sites or otherwise impact surface catalytic chemistry. Solvation of the cation-metal surface structure was investigated using explicit water models. Computed equilibrium potentials for alkali cation adsorption suggest that alkali and alkaline earth cations will specifically adsorb onto Pt(111) and Pd(111) surfaces in the potential range of hydrogen oxidation and hydrogen evolution catalysis in alkaline solutions.

  9. Provision of lipid-based nutrient supplements to Honduran children increases their dietary macro- and micronutrient intake without displacing other foods.

    PubMed

    Flax, Valerie L; Siega-Riz, Anna Maria; Reinhart, Greg A; Bentley, Margaret E

    2015-12-01

    Inadequate energy intake and poor diet quality are important causes of chronic child undernutrition. Strategies for improving diet quality using lipid-based nutrient supplements (LNS) are currently being tested in several countries. To date, information on children's dietary intakes during LNS use is available only from Africa. In this study, we collected 24-h dietary recalls at baseline, 3, 6, 9 and 12 months on Honduran children (n = 298) participating in a cluster-randomised trial of LNS. Generalised estimating equations were used to examine differences in number of servings of 12 food groups in the LNS and control arms, and multi-level mixed effects models were used to compare macro- and micronutrient intakes. Models accounted for clustering and adjusted for child's age, season and breastfeeding status. Mean daily servings of 12 food groups did not differ by study arm at baseline and remained similar throughout the study with the exception of groups that were partially or entirely supplied by LNS (nuts and nut butters, fats, and sweets). Baseline intakes of energy, fat, carbohydrates, protein, folate and vitamin A, but not vitamin B12, iron and zinc were lower in the LNS than control arm. The change in all macro- and micronutrients from baseline to each study visit was larger for the LNS arm than the control, except for carbohydrates from baseline to 9 months. These findings indicate that LNS improved the macro- and micronutrient intakes of young non-malnourished Honduran children without replacing other foods in their diet.

  10. Impedimetric transduction of swelling in pH-responsive hydrogels.

    PubMed

    Mac Kenna, Nicky; Calvert, Paul; Morrin, Aoife

    2015-05-01

    A pH-responsive hydrogel composed of an aliphatic diamine cross-linked with polyethylene glycol diglycidyl ether (PEGDGE) using a single, rapid polymerisation step has been used to detect glucose by entrapping glucose oxidase (GOx) within its cationic network. The swelling response of hydrogel disks on exposure to glucose were optimised through variation of factors including the cross-linking density of the network, GOx loading and the addition of catalase. Hydrogel-modified carbon cloth electrodes were also prepared and characterised using voltammetric and impedimetric techniques. Non-faradaic electrochemical impedance spectroscopy (EIS) and gravimetry were both employed to track the swelling response of the gels quantitatively. The clear potential of utilising impedance to transduce hydrogel swelling was demonstrated where a linear decrease in gel resistance (Rgel) corresponding to the swelling response was observed in the range 1 to 100 μM. A dramatic increase in the limit of detection of six orders of magnitude over the gravimetric measurement was achieved (from 0.33 mM to 0.08 μM). This increased sensitivity, coupled with the textile-based electrode substrate approach opens the potential applicability of this system for monitoring glucose concentration via the skin by sweat or interstitial fluid (ISF). PMID:25768307

  11. Impedimetric transduction of swelling in pH-responsive hydrogels.

    PubMed

    Mac Kenna, Nicky; Calvert, Paul; Morrin, Aoife

    2015-05-01

    A pH-responsive hydrogel composed of an aliphatic diamine cross-linked with polyethylene glycol diglycidyl ether (PEGDGE) using a single, rapid polymerisation step has been used to detect glucose by entrapping glucose oxidase (GOx) within its cationic network. The swelling response of hydrogel disks on exposure to glucose were optimised through variation of factors including the cross-linking density of the network, GOx loading and the addition of catalase. Hydrogel-modified carbon cloth electrodes were also prepared and characterised using voltammetric and impedimetric techniques. Non-faradaic electrochemical impedance spectroscopy (EIS) and gravimetry were both employed to track the swelling response of the gels quantitatively. The clear potential of utilising impedance to transduce hydrogel swelling was demonstrated where a linear decrease in gel resistance (Rgel) corresponding to the swelling response was observed in the range 1 to 100 μM. A dramatic increase in the limit of detection of six orders of magnitude over the gravimetric measurement was achieved (from 0.33 mM to 0.08 μM). This increased sensitivity, coupled with the textile-based electrode substrate approach opens the potential applicability of this system for monitoring glucose concentration via the skin by sweat or interstitial fluid (ISF).

  12. Cationic Polyamidoamine Dendrimers as Modulators of EGFR Signaling In Vitro and In Vivo.

    PubMed

    Akhtar, Saghir; Al-Zaid, Bashayer; El-Hashim, Ahmed Z; Chandrasekhar, Bindu; Attur, Sreeja; Yousif, Mariam H M; Benter, Ibrahim F

    2015-01-01

    Cationic polyamidoamine (PAMAM) dendrimers are branch-like spherical polymers being investigated for a variety of applications in nanomedicine including nucleic acid drug delivery. Emerging evidence suggests they exhibit intrinsic biological and toxicological effects but little is known of their interactions with signal transduction pathways. We previously showed that the activated (fragmented) generation (G) 6 PAMAM dendrimer, Superfect (SF), stimulated epidermal growth factor receptor (EGFR) tyrosine kinase signaling-an important signaling cascade that regulates cell growth, survival and apoptosis- in cultured human embryonic kidney (HEK 293) cells. Here, we firstly studied the in vitro effects of Polyfect (PF), a non-activated (intact) G6 PAMAM dendrimer, on EGFR tyrosine kinase signaling via extracellular-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK) in cultured HEK 293 cells and then compared the in vivo effects of a single administration (10mg/kg i.p) of PF or SF on EGFR signaling in the kidneys of normal and diabetic male Wistar rats. Polyfect exhibited a dose- and time-dependent inhibition of EGFR, ERK1/2 and p38 MAPK phosphorylation in HEK-293 cells similar to AG1478, a selective EGFR inhibitor. Administration of dendrimers to non-diabetic or diabetic animals for 24h showed that PF inhibited whereas SF stimulated EGFR phosphorylation in the kidneys of both sets of animals. PF-mediated inhibition of EGFR phosphorylation as well as SF or PF-mediated apoptosis in HEK 293 cells could be significantly reversed by co-treatment with antioxidants such as tempol implying that both these effects involved an oxidative stress-dependent mechanism. These results show for the first time that SF and PF PAMAM dendrimers can differentially modulate the important EGFR signal transduction pathway in vivo and may represent a novel class of EGFR modulators. These findings could have important clinical implications for the use of PAMAM dendrimers

  13. Cationic Polyamidoamine Dendrimers as Modulators of EGFR Signaling In Vitro and In Vivo

    PubMed Central

    Akhtar, Saghir; Al-Zaid, Bashayer; El-Hashim, Ahmed Z.; Chandrasekhar, Bindu; Attur, Sreeja; Yousif, Mariam H. M.; Benter, Ibrahim F.

    2015-01-01

    Cationic polyamidoamine (PAMAM) dendrimers are branch-like spherical polymers being investigated for a variety of applications in nanomedicine including nucleic acid drug delivery. Emerging evidence suggests they exhibit intrinsic biological and toxicological effects but little is known of their interactions with signal transduction pathways. We previously showed that the activated (fragmented) generation (G) 6 PAMAM dendrimer, Superfect (SF), stimulated epidermal growth factor receptor (EGFR) tyrosine kinase signaling—an important signaling cascade that regulates cell growth, survival and apoptosis- in cultured human embryonic kidney (HEK 293) cells. Here, we firstly studied the in vitro effects of Polyfect (PF), a non-activated (intact) G6 PAMAM dendrimer, on EGFR tyrosine kinase signaling via extracellular-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK) in cultured HEK 293 cells and then compared the in vivo effects of a single administration (10mg/kg i.p) of PF or SF on EGFR signaling in the kidneys of normal and diabetic male Wistar rats. Polyfect exhibited a dose- and time-dependent inhibition of EGFR, ERK1/2 and p38 MAPK phosphorylation in HEK-293 cells similar to AG1478, a selective EGFR inhibitor. Administration of dendrimers to non-diabetic or diabetic animals for 24h showed that PF inhibited whereas SF stimulated EGFR phosphorylation in the kidneys of both sets of animals. PF-mediated inhibition of EGFR phosphorylation as well as SF or PF-mediated apoptosis in HEK 293 cells could be significantly reversed by co-treatment with antioxidants such as tempol implying that both these effects involved an oxidative stress-dependent mechanism. These results show for the first time that SF and PF PAMAM dendrimers can differentially modulate the important EGFR signal transduction pathway in vivo and may represent a novel class of EGFR modulators. These findings could have important clinical implications for the use of PAMAM

  14. Cationic Polyamidoamine Dendrimers as Modulators of EGFR Signaling In Vitro and In Vivo.

    PubMed

    Akhtar, Saghir; Al-Zaid, Bashayer; El-Hashim, Ahmed Z; Chandrasekhar, Bindu; Attur, Sreeja; Yousif, Mariam H M; Benter, Ibrahim F

    2015-01-01

    Cationic polyamidoamine (PAMAM) dendrimers are branch-like spherical polymers being investigated for a variety of applications in nanomedicine including nucleic acid drug delivery. Emerging evidence suggests they exhibit intrinsic biological and toxicological effects but little is known of their interactions with signal transduction pathways. We previously showed that the activated (fragmented) generation (G) 6 PAMAM dendrimer, Superfect (SF), stimulated epidermal growth factor receptor (EGFR) tyrosine kinase signaling-an important signaling cascade that regulates cell growth, survival and apoptosis- in cultured human embryonic kidney (HEK 293) cells. Here, we firstly studied the in vitro effects of Polyfect (PF), a non-activated (intact) G6 PAMAM dendrimer, on EGFR tyrosine kinase signaling via extracellular-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK) in cultured HEK 293 cells and then compared the in vivo effects of a single administration (10mg/kg i.p) of PF or SF on EGFR signaling in the kidneys of normal and diabetic male Wistar rats. Polyfect exhibited a dose- and time-dependent inhibition of EGFR, ERK1/2 and p38 MAPK phosphorylation in HEK-293 cells similar to AG1478, a selective EGFR inhibitor. Administration of dendrimers to non-diabetic or diabetic animals for 24h showed that PF inhibited whereas SF stimulated EGFR phosphorylation in the kidneys of both sets of animals. PF-mediated inhibition of EGFR phosphorylation as well as SF or PF-mediated apoptosis in HEK 293 cells could be significantly reversed by co-treatment with antioxidants such as tempol implying that both these effects involved an oxidative stress-dependent mechanism. These results show for the first time that SF and PF PAMAM dendrimers can differentially modulate the important EGFR signal transduction pathway in vivo and may represent a novel class of EGFR modulators. These findings could have important clinical implications for the use of PAMAM dendrimers

  15. Full Piezoelectric Multilayer-Stacked Hybrid Actuation/Transduction Systems

    NASA Technical Reports Server (NTRS)

    Su, Ji; Jiang, Xiaoning; Zu, Tian-Bing

    2011-01-01

    The Stacked HYBATS (Hybrid Actuation/Transduction system) demonstrates significantly enhanced electromechanical performance by using the cooperative contributions of the electromechanical responses of multilayer, stacked negative strain components and positive strain components. Both experimental and theoretical studies indicate that, for Stacked HYBATS, the displacement is over three times that of a same-sized conventional flextensional actuator/transducer. The coupled resonance mode between positive strain and negative strain components of Stacked HYBATS is much stronger than the resonance of a single element actuation only when the effective lengths of the two kinds of elements match each other. Compared with the previously invented hybrid actuation system (HYBAS), the multilayer Stacked HYBATS can be designed to provide high mechanical load capability, low voltage driving, and a highly effective piezoelectric constant. The negative strain component will contract, and the positive strain component will expand in the length directions when an electric field is applied on the device. The interaction between the two elements makes an enhanced motion along the Z direction for Stacked-HYBATS. In order to dominate the dynamic length of Stacked-HYBATS by the negative strain component, the area of the cross-section for the negative strain component will be much larger than the total cross-section areas of the two positive strain components. The transverse strain is negative and longitudinal strain positive in inorganic materials, such as ceramics/single crystals. Different piezoelectric multilayer stack configurations can make a piezoelectric ceramic/single-crystal multilayer stack exhibit negative strain or positive strain at a certain direction without increasing the applied voltage. The difference of this innovation from the HYBAS is that all the elements can be made from one-of-a-kind materials. Stacked HYBATS can provide an extremely effective piezoelectric

  16. Neural transduction in Xenopus laevis lateral line system.

    PubMed

    Strelioff, D; Honrubia, V

    1978-03-01

    1. The process of neural excitation in hair cell systems was studied in an in vitro preparation of the Xenopus laevis (African clawed toad) lateral line organ. A specially designed stimulus chamber was used to apply accurately controlled pressure, water movement, or electrical stimuli, and to record the neural responses of the two afferent fibers innervating each organ or stitch. The objective of the study was to determine the characteristics of the neural responses to these stimuli, and thus gain insight into the transduction process. 2. A sustained deflection of the hair cell cilia due to a constant flow of water past the capula resulted in a maintained change in the mean firing rate (MFR) of the afferent fibers. The data also demonstrated that the neural response was proportional to the velocity of the water flow and indicated that both deflection and movement of the cilia were the effective physiological stimuli for this hair cell system. 3. The preparations responded to sinusoidal water movements (past the capula) over the entire frequency range of the stimulus chamber, 0.1-130 Hz, and were most sensitive between 10 and 40 Hz. The variation of the MFR and the percent modulation indicated that the average dynamic range of each organ was 23.5 dB. 4. The thresholds, if any, for sustained pressure changes and for sinusoidal pressure variations in the absence of water movements were very high. Due to the limitations of the stimulus chamber it was not possible to generate pressure stimuli of sufficient magnitude to elicit a neural response without also generating suprathreshold water-movement stimuli. Sustained pressures had no detectable effect on the neural response to water-movement stimuli. 5. The preparations were very sensitive to electrical potentials applied across the toad skin on which the hair cells were located. Potentials which made the ciliated surfaces of the hair cells positive with respect to their bases increased the MFR of the fibers, whereas

  17. Comparative analysis of cation/proton antiporter superfamily in plants

    SciTech Connect

    Ye, Chuyu; Yang, Xiaohan; Xia, Xinli; Yin, Weilun

    2013-01-01

    The cation/proton antiporter superfamily is associated with the transport of monovalent cations across membranes. This superfamily was annotated in the Arabidopsis genome and some members were functionally characterized. In the present study, a systematic analysis of the cation/proton antiporter genes in diverse plant specieswas reported.We identified 240 cation/proton antiporters in alga, moss, and angiosperm. A phylogenetic tree was constructed showing these 240members are separated into three families, i.e., Na+/H+ exchangers, K+ efflux antiporters, and cation/H+ exchangers. Our analysis revealed that tandem and/or segmental duplications contribute to the expansion of cation/H+ exchangers in the examined angiospermspecies. Sliding windowanalysis of the nonsynonymous/synonymous substitution ratios showed some differences in the evolutionary fate of cation/proton antiporter paralogs. Furthermore, we identified over-represented motifs among these 240 proteins and foundmostmotifs are family specific, demonstrating diverse evolution of the cation/proton antiporters among three families. In addition, we investigated the co-expressed genes of the cation/proton antiporters in Arabidopsis thaliana. The results showed some biological processes are enriched in the co-expressed genes, suggesting the cation/proton antiporters may be involved in these biological processes. Taken together, this study furthers our knowledge on cation/proton antiporters in plants.

  18. Radiolytic generation of radical cations in xenon matrices. Tetramethylcyclopropane radical cation and its transformations

    SciTech Connect

    Qin, X.Z.; Trifunac, A.D. )

    1990-04-05

    Radiolytic generation of radical cations in xenon matrices containing electron scavengers is illustrated by studying the 1,1,2,2-tetramethylcyclopropane radical cation. Dilute and concentrated solutions of tetramethylcyclopropane in xenon without electron scavengers and neat tetramethylcyclopropane yielded neutral radicals upon {gamma}-irradiation. Speculation on the mechanisms of radical formation is presented. The radical species observed in the {gamma}-irradiation of neat tetramethylcyclopropane appears to be identical with the paramagnetic species observed in CF{sub 2}ClCFCl{sub 2} above 120 K, suggesting that a neutral radical rather than the ring-opened distonic radical cation is observed in the CF{sub 2}ClCFCl{sub 2} matrix.

  19. Cation–cation interactions and cation exchange in a series of isostructural framework uranyl tungstates

    SciTech Connect

    Balboni, Enrica; Burns, Peter C.

    2014-05-01

    The isotypical compounds (UO{sub 2}){sub 3}(WO{sub 6})(H{sub 2}O){sub 5} (1), Ag(UO{sub 2}){sub 3}(WO{sub 6})(OH)(H{sub 2}O){sub 3} (2), K(UO{sub 2}){sub 3}(WO{sub 6})OH(H{sub 2}O){sub 4} (3), Rb(UO{sub 2}){sub 3}(WO{sub 6})(OH)(H{sub 2}O){sub 3.5} (4), and Cs(UO{sub 2}){sub 3}(WO{sub 6})OH(H{sub 2}O){sub 3} (5) were synthesized, characterized, and their structures determined. Each crystallizes in space group Cc. (1): a=12.979 (3), b=10.238 (2), c=11.302 (2), β=102.044 (2); (2): a=13.148 (2), b=9.520 (1), c=11.083 (2), β=101.568 (2); (3): a=13.111 (8), b=9.930 (6), c=11.242 (7), β=101.024 (7); (4): a=12.940 (2), b=10.231 (2), c=11.259(2), β=102.205 (2); (5): a=12.983 (3), b=10.191 (3), c=11.263 (4), β=101.661 (4). Compounds 1–5 are a framework of uranyl and tungsten polyhedra containing cation–cation interactions. The framework has three symmetrically distinct U(VI) cations, one tungsten, sixteen to eighteen oxygen atoms, and in 2–5, one monovalent cation. Each atom occupies a general position. Each U(VI) cation is present as a typical (UO{sub 2}){sup 2+} uranyl ion in an overall pentagonal bipyramidal coordination environment. Each pentagonal bipyramid shares two equatorial edges with two other pentagonal bipyramids, forming a trimer. Trimers are connected into chains by edge-sharing with WO{sub 6} octahedra. Chains are linked through cation–cation interactions between two symmetrically independent uranyl ions. This yields a remarkably complex system of intersecting channels that extend along [0 0 1] and [−1 1 0]. The cation exchange properties of 2 and 3 were characterized at room temperature and at 140 °C. - Graphical abstract: Chains of uranium and tungsten polyhedra are connected into a three dimensional framework by cation–cation interactions occurring between two symmetrically independent uranyl pentagonal bipyramids. Monovalent cations present in channels within the structure can be exchanged by room temperature or mild hydrothermal

  20. The use of cationic nanogels to deliver proteins to myeloma cells and primary T lymphocytes that poorly express heparan sulfate.

    PubMed

    Watanabe, Kozo; Tsuchiya, Yumiko; Kawaguchi, Yoshinori; Sawada, Shin-ichi; Ayame, Hirohito; Akiyoshi, Kazunari; Tsubata, Takeshi

    2011-09-01

    Fusion proteins containing protein transduction domain (PTD) are widely used for intracellular delivery of exogenous proteins. PTD-mediated delivery requires expression of heparan sulfate on the surface of the target cells. However, some of metastatic tumor cells and primary lymphocytes poorly express heparan sulfate. Here we demonstrate that proteins complexed with nanosize hydrogels formed by cationic cholesteryl group-bearing pullulans (cCHP) are efficiently delivered to myeloma cells and primary CD4(+) T lymphocytes probably by induction of macropinocytosis, although these cells are resistant to PTD-mediated protein delivery as a consequence of poor heparan sulfate expression. The anti-apoptotic protein Bcl-xL delivered by cCHP nanogels efficiently blocked apoptosis of these cells, establishing functional regulation of cells by proteins delivered by cCHP nanogels. Thus, cCHP nanogel is a useful tool to deliver proteins for development of new cancer therapy and immune regulation. PMID:21605901

  1. Radical cations of quadricyclane and norbornadiene in polar ZSM-5 matrices: Radical cation photochemical transformations without photons

    SciTech Connect

    Barnabas, M.V.; Trifunac, A.D.

    1994-06-01

    Radical cations of quadricyclane (Q) and norbornadiene (NBD) are produced by {gamma}-radiolysis in zeolites. In polar ZSM-5, only one radical cation is initially observed below 100K. Increasing the temperature above 200K gives rise to the cyclopentadiene radical cation. Higher temperatures (>360K) give rise to the cyclopenten-4-yl radical. The observation of cyclopentadiene radical cation implies the occurrence of the reverse Diels-Alder reaction. This is a thermally forbidden, photochemically allowed, process, which is made possible by the interaction of the polar zeolite matrix sites with parent NBD and Q radical cations.

  2. A Lipid Based Antigen Delivery System Efficiently Facilitates MHC Class-I Antigen Presentation in Dendritic Cells to Stimulate CD8+ T Cells

    NASA Astrophysics Data System (ADS)

    Maji, Mithun; Mazumder, Saumyabrata; Bhattacharya, Souparno; Choudhury, Somsubhra Thakur; Sabur, Abdus; Shadab, Md.; Bhattacharya, Pradyot; Ali, Nahid

    2016-06-01

    The most effective strategy for protection against intracellular infections such as Leishmania is vaccination with live parasites. Use of recombinant proteins avoids the risks associated with live vaccines. However, due to low immunogenicity, they fail to trigger T cell responses particularly of CD8+ cells requisite for persistent immunity. Previously we showed the importance of protein entrapment in cationic liposomes and MPL as adjuvant for elicitation of CD4+ and CD8+ T cell responses for long-term protection. In this study we investigated the role of cationic liposomes on maturation and antigen presentation capacity of dendritic cells (DCs). We observed that cationic liposomes were taken up very efficiently by DCs and transported to different cellular sites. DCs activated with liposomal rgp63 led to efficient presentation of antigen to specific CD4+ and CD8+ T cells. Furthermore, lymphoid CD8+ T cells from liposomal rgp63 immunized mice demonstrated better proliferative ability when co-cultured ex vivo with stimulated DCs. Addition of MPL to vaccine enhanced the antigen presentation by DCs and induced more efficient antigen specific CD8+ T cell responses when compared to free and liposomal antigen. These liposomal formulations presented to CD8+ T cells through TAP-dependent MHC-I pathway offer new possibilities for a safe subunit vaccine.

  3. A Lipid Based Antigen Delivery System Efficiently Facilitates MHC Class-I Antigen Presentation in Dendritic Cells to Stimulate CD8(+) T Cells.

    PubMed

    Maji, Mithun; Mazumder, Saumyabrata; Bhattacharya, Souparno; Choudhury, Somsubhra Thakur; Sabur, Abdus; Shadab, Md; Bhattacharya, Pradyot; Ali, Nahid

    2016-01-01

    The most effective strategy for protection against intracellular infections such as Leishmania is vaccination with live parasites. Use of recombinant proteins avoids the risks associated with live vaccines. However, due to low immunogenicity, they fail to trigger T cell responses particularly of CD8(+) cells requisite for persistent immunity. Previously we showed the importance of protein entrapment in cationic liposomes and MPL as adjuvant for elicitation of CD4(+) and CD8(+) T cell responses for long-term protection. In this study we investigated the role of cationic liposomes on maturation and antigen presentation capacity of dendritic cells (DCs). We observed that cationic liposomes were taken up very efficiently by DCs and transported to different cellular sites. DCs activated with liposomal rgp63 led to efficient presentation of antigen to specific CD4(+) and CD8(+) T cells. Furthermore, lymphoid CD8(+) T cells from liposomal rgp63 immunized mice demonstrated better proliferative ability when co-cultured ex vivo with stimulated DCs. Addition of MPL to vaccine enhanced the antigen presentation by DCs and induced more efficient antigen specific CD8(+) T cell responses when compared to free and liposomal antigen. These liposomal formulations presented to CD8(+) T cells through TAP-dependent MHC-I pathway offer new possibilities for a safe subunit vaccine. PMID:27251373

  4. A Lipid Based Antigen Delivery System Efficiently Facilitates MHC Class-I Antigen Presentation in Dendritic Cells to Stimulate CD8+ T Cells

    PubMed Central

    Maji, Mithun; Mazumder, Saumyabrata; Bhattacharya, Souparno; Choudhury, Somsubhra Thakur; Sabur, Abdus; Shadab, Md.; Bhattacharya, Pradyot; Ali, Nahid

    2016-01-01

    The most effective strategy for protection against intracellular infections such as Leishmania is vaccination with live parasites. Use of recombinant proteins avoids the risks associated with live vaccines. However, due to low immunogenicity, they fail to trigger T cell responses particularly of CD8+ cells requisite for persistent immunity. Previously we showed the importance of protein entrapment in cationic liposomes and MPL as adjuvant for elicitation of CD4+ and CD8+ T cell responses for long-term protection. In this study we investigated the role of cationic liposomes on maturation and antigen presentation capacity of dendritic cells (DCs). We observed that cationic liposomes were taken up very efficiently by DCs and transported to different cellular sites. DCs activated with liposomal rgp63 led to efficient presentation of antigen to specific CD4+ and CD8+ T cells. Furthermore, lymphoid CD8+ T cells from liposomal rgp63 immunized mice demonstrated better proliferative ability when co-cultured ex vivo with stimulated DCs. Addition of MPL to vaccine enhanced the antigen presentation by DCs and induced more efficient antigen specific CD8+ T cell responses when compared to free and liposomal antigen. These liposomal formulations presented to CD8+ T cells through TAP-dependent MHC-I pathway offer new possibilities for a safe subunit vaccine. PMID:27251373

  5. A transductive neuro-fuzzy controller: application to a drilling process.

    PubMed

    Gajate, Agustín; Haber, Rodolfo E; Vega, Pastora I; Alique, José R

    2010-07-01

    Recently, new neuro-fuzzy inference algorithms have been developed to deal with the time-varying behavior and uncertainty of many complex systems. This paper presents the design and application of a novel transductive neuro-fuzzy inference method to control force in a high-performance drilling process. The main goal is to study, analyze, and verify the behavior of a transductive neuro-fuzzy inference system for controlling this complex process, specifically addressing the dynamic modeling, computational efficiency, and viability of the real-time application of this algorithm as well as assessing the topology of the neuro-fuzzy system (e.g., number of clusters, number of rules). A transductive reasoning method is used to create local neuro-fuzzy models for each input/output data set in a case study. The direct and inverse dynamics of a complex process are modeled using this strategy. The synergies among fuzzy, neural, and transductive strategies are then exploited to deal with process complexity and uncertainty through the application of the neuro-fuzzy models within an internal model control (IMC) scheme. A comparative study is made of the adaptive neuro-fuzzy inference system (ANFIS) and the suggested method inspired in a transductive neuro-fuzzy inference strategy. The two neuro-fuzzy strategies are evaluated in a real drilling force control problem. The experimental results demonstrated that the transductive neuro-fuzzy control system provides a good transient response (without overshoot) and better error-based performance indices than the ANFIS-based control system. In particular, the IMC system based on a transductive neuro-fuzzy inference approach reduces the influence of the increase in cutting force that occurs as the drill depth increases, reducing the risk of rapid tool wear and catastrophic tool breakage.

  6. A transductive neuro-fuzzy controller: application to a drilling process.

    PubMed

    Gajate, Agustín; Haber, Rodolfo E; Vega, Pastora I; Alique, José R

    2010-07-01

    Recently, new neuro-fuzzy inference algorithms have been developed to deal with the time-varying behavior and uncertainty of many complex systems. This paper presents the design and application of a novel transductive neuro-fuzzy inference method to control force in a high-performance drilling process. The main goal is to study, analyze, and verify the behavior of a transductive neuro-fuzzy inference system for controlling this complex process, specifically addressing the dynamic modeling, computational efficiency, and viability of the real-time application of this algorithm as well as assessing the topology of the neuro-fuzzy system (e.g., number of clusters, number of rules). A transductive reasoning method is used to create local neuro-fuzzy models for each input/output data set in a case study. The direct and inverse dynamics of a complex process are modeled using this strategy. The synergies among fuzzy, neural, and transductive strategies are then exploited to deal with process complexity and uncertainty through the application of the neuro-fuzzy models within an internal model control (IMC) scheme. A comparative study is made of the adaptive neuro-fuzzy inference system (ANFIS) and the suggested method inspired in a transductive neuro-fuzzy inference strategy. The two neuro-fuzzy strategies are evaluated in a real drilling force control problem. The experimental results demonstrated that the transductive neuro-fuzzy control system provides a good transient response (without overshoot) and better error-based performance indices than the ANFIS-based control system. In particular, the IMC system based on a transductive neuro-fuzzy inference approach reduces the influence of the increase in cutting force that occurs as the drill depth increases, reducing the risk of rapid tool wear and catastrophic tool breakage. PMID:20659865

  7. Plasmid Transduction Using Bacteriophage Φadh for Expression of CC Chemokines by Lactobacillus gasseri ADH▿

    PubMed Central

    Damelin, Leonard H.; Mavri-Damelin, Demetra; Klaenhammer, Todd R.; Tiemessen, Caroline T.

    2010-01-01

    Vaginal mucosal microfloras are typically dominated by Gram-positive Lactobacillus species, and colonization of vaginal mucosa by exogenous microbicide-secreting Lactobacillus strains has been proposed as a means of enhancing this natural mucosal barrier against human immunodeficiency virus (HIV) infection. We asked whether an alternative strategy could be utilized whereby anti-HIV molecules are expressed within the cervicovaginal milieu by endogenous vaginal Lactobacillus populations which have been engineered in situ via transduction. In this study, we therefore investigated the feasibility of utilizing transduction for the expression of two HIV coreceptor antagonists, the CC chemokines CCL5 and CCL3, in a predominant vaginal Lactobacillus species, Lactobacillus gasseri. Modifying a previously established transduction model, which utilizes L. gasseri ADH and its prophage Φadh, we show that mitomycin C induction of L. gasseri ADH transformants containing pGK12-based plasmids with CCL5 and CCL3 expression and secretion cassettes (under the control of promoters P6 and P59, respectively) and a 232-bp Φadh cos site fragment results in the production of transducing particles which contain 8 to 9 copies of concatemeric plasmid DNA. High-frequency transduction for these particles (almost 6 orders of magnitude greater than that for pGK12 alone) was observed, and transductants were found to contain recircularized expression plasmids upon subsequent culture. Importantly, transductants produced CC chemokines at levels comparable to those produced by electroporation-derived transformants. Our findings therefore lend support to the potential use of transduction in vaginal Lactobacillus species as a novel strategy for the prevention of HIV infection across mucosal membranes. PMID:20418431

  8. Plasmid transduction using bacteriophage Phi(adh) for expression of CC chemokines by Lactobacillus gasseri ADH.

    PubMed

    Damelin, Leonard H; Mavri-Damelin, Demetra; Klaenhammer, Todd R; Tiemessen, Caroline T

    2010-06-01

    Vaginal mucosal microfloras are typically dominated by Gram-positive Lactobacillus species, and colonization of vaginal mucosa by exogenous microbicide-secreting Lactobacillus strains has been proposed as a means of enhancing this natural mucosal barrier against human immunodeficiency virus (HIV) infection. We asked whether an alternative strategy could be utilized whereby anti-HIV molecules are expressed within the cervicovaginal milieu by endogenous vaginal Lactobacillus populations which have been engineered in situ via transduction. In this study, we therefore investigated the feasibility of utilizing transduction for the expression of two HIV coreceptor antagonists, the CC chemokines CCL5 and CCL3, in a predominant vaginal Lactobacillus species, Lactobacillus gasseri. Modifying a previously established transduction model, which utilizes L. gasseri ADH and its prophage Phiadh, we show that mitomycin C induction of L. gasseri ADH transformants containing pGK12-based plasmids with CCL5 and CCL3 expression and secretion cassettes (under the control of promoters P6 and P59, respectively) and a 232-bp Phiadh cos site fragment results in the production of transducing particles which contain 8 to 9 copies of concatemeric plasmid DNA. High-frequency transduction for these particles (almost 6 orders of magnitude greater than that for pGK12 alone) was observed, and transductants were found to contain recircularized expression plasmids upon subsequent culture. Importantly, transductants produced CC chemokines at levels comparable to those produced by electroporation-derived transformants. Our findings therefore lend support to the potential use of transduction in vaginal Lactobacillus species as a novel strategy for the prevention of HIV infection across mucosal membranes.

  9. Structural Evolution of Environmentally Responsive Cationic Liposome–DNA Complexes with a Reducible Lipid Linker

    PubMed Central

    Shirazi, Rahau S.; Ewert, Kai K.; Silva, Bruno F. B.; Leal, Cecilia; Li, Youli; Safinya, Cyrus R.

    2012-01-01

    Environmentally responsive materials, i.e., materials that respond to changes in their environment with a change in their properties or structure, are attracting an increasing amount of interest. We recently designed and synthesized a series of cleavable multivalent lipids (CMVLn, with n = 2 to 5 the number of positive headgroup charges at full protonation) with a disulfide bond in the linker between cationic headgroup and hydrophobic tails. The self-assembled complexes of the CMVLs and DNA are a prototypical environmentally responsive material, undergoing extensive structural rearrangement when exposed to reducing agents. We investigated the structural evolution of CMVL–DNA complexes at varied complex composition, temperature and incubation time using small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). A related lipid with a stable linker, TMVL4, was used as a control. In a nonreducing environment CMVL–DNA complexes form the lamellar (LαC) phase, with DNA rods sandwiched between lipid bilayers. However, new self-assembled phases form when the disulfide linker is cleaved by dithiothreitol or the biologically relevant reducing agent glutathione. The released DNA and cleaved CMVL headgroups form a “loosely organized” phase, giving rise to a characteristic broad SAXS correlation profile. CMVLs of high headgroup charge also form condensed DNA bundles. Intriguingly, the cleaved hydrophobic tails of the CMVLs reassemble into tilted chain-ordered Lβ′ phases upon incubation at physiological temperature (37 °C), as indicated by characteristic WAXS peaks. X-ray scattering further reveals that two of the three phases (LβF, LβL, and LβI) comprised by the Lβ′ phase coexist in these samples. The described system may have applications in lipid-based nanotechnologies. PMID:22616637

  10. Nonlinearity of cationic aromatic amine sorption to aluminosilicates and soils: role of intermolecular cation-π interactions.

    PubMed

    Vasudevan, Dharni; Arey, Teresa A; Dickstein, Daniel R; Newman, Mark H; Zhang, Tina Y; Kinnear, Heather M; Bader, Mohammad M

    2013-12-17

    Through the study of substituted anilines and benzylamines, we demonstrated that cooperative cation-π, π-π, and van der Waals interactions can increase aromatic cationic amine sorption to Na/Ca-montmorillonite well beyond the extent expected by cation exchange alone. Cationic amines exhibiting cooperative interactions displayed nonlinear S-shaped isotherms and increased affinity for the sorbent at low surface coverage; parallel cation exchange and cooperative interactions were noted above a sorption threshold of 0.3-2.3% of exchange sites occupied. Our experiments revealed the predominance of intermolecular cation-π interactions, which occurred between the π system of a compound retained on the surface via cation exchange and the cationic amine group of an adjacent molecule. Compounds with greater amine charge/area and electron-donating substituents that allowed for greater electron density at the center of the aromatic ring showed a greater potential for cation-π interactions on montmorillonite surfaces. However, benzylamine sorption to nine soils, at charge loadings comparable to the experiments with montmorillonite, revealed no significant cooperative interactions. It appears that cation-π interactions may be likely in soils with exceptionally high cation exchange capacities (>0.7 mol charge/kg) and low organic matter contents, abundant in montmorillonite and other expanding clay minerals.

  11. Simulated Transport of Three Cations Through Porous Media: Effect of Different Approaches to Modeling Cation Exchange Reactions

    NASA Astrophysics Data System (ADS)

    Grant, S. A.; Mansell, R. S.; Bloom, S. A.; Rhue, R. D.

    1995-01-01

    Batch cation exchange and column experiments were conducted to evaluate selectivity coefficients which have been suggested for describing cation exchange reactions in solute transport models. Vanselow selectivity coefficients were calculated for cation exchange equilibria with a cation resin and for equilibria reported in the literature with a Yolo loam soil. Experimental column data were compared with data from simulations generated by a numerical solute transport model to evaluate Vanselow, Gaines-Thomas, and statistical thermodynamic selectivity coefficients. With the cation resin, the statistical thermodynamic selectivity coefficient gave the most reliable estimate of column effluent cation concentrations. In a column packed with the Yolo loam soil, the Vanselow selectivity coefficient gave the most accurate prediction of column response. Use of variable (as opposed to fixed) Vanselow selectivity coefficients gave more accurate predictions of column experiments. The use of ternary cation exchange data did not improve predictions of column response.

  12. Fragmentation Pathways in the Uracil Radical Cation

    SciTech Connect

    Zhou, Congyi; Matsika, Spiridoula; Kotur, Marija; Weinacht, Thomas C.

    2012-08-24

    We investigate pathways for fragmentation in the uracil radical cation using ab initio electronic structure calculations. We focus on the main fragments produced in pump–probe dissociative ionization experiments. These are fragments with mass to charge ratios (m/z) of 69, 28, 41, and 42. Barriers to dissociation along the ground ionic surface are reported, which provide an estimate of the energetic requirements for the production of the main fragments. Finally, direct and sequential fragmentation mechanisms have been analyzed, and it is concluded that sequential fragmentation after production of fragment with m/z 69 is the dominant mechanism for the production of the smaller fragments.

  13. Cationic bituminous emulsions and emulsion aggregate slurries

    SciTech Connect

    Schilling, P.

    1986-07-01

    A cationic bituminous emulsion is described which consists of from about 30% to about 80% by weight of bitumen, from about 0.1% to about 10% by weight of an emulsifier selected from the group consisting of reaction products of a polyamine reacted with a member of the group consisting of epoxidized unsaturated fatty acids of chain lengths between C/sub 8/ and C/sub 22/ and the esters thereof and adding water to make up 100% by weight, the emulsion having a pH in the range of from 2-7.

  14. Development of cationic nanocrystals for ocular delivery.

    PubMed

    Romero, Gregori B; Keck, Cornelia M; Müller, Rainer H; Bou-Chacra, Nadia A

    2016-10-01

    A cationic nanocrystal formulation containing dexamethasone acetate nanocrystals (0.05%) and polymyxin B (0.10%) for ophthalmic application was produced using a self-developed small scale method for wet bead milling. The formulation developed offers the advantage of increased saturation solubility of the drug (due to the nano-size of the crystals) and increased residence time in the eye (due to small size and increased mucoadhesion by the cationic charge) resulting ultimately in potential increased bioavailability. Characterization of the nanosuspensions by photon correlation spectroscopy (PCS) and transmission electron microscopy showed that the production method was successful in achieving dexamethasone crystals in the range of about 200-250nm. The physical stabilization of the nanocrystals and generation of the positive charge were realized by using cetylpyridinium chloride (CPC) and benzalkonium chloride (BAC) at the concentration of 0.01%. In contrast to other cationic excipients, they are regulatorily accepted due to their use as preservatives. The drug polymyxin B also contributed to the positive charge. Positive zeta potentials in the range +20 to +30mV were achieved. Isotonicity was adjusted using NaCl and non-ionic excipients (glycerol, sorbitol, dextrose). Physical and chemical stabilities were monitored for a period of 6months at room temperature, 5°C and 40°C. Particle size of the bulk population assessed by PCS remained practically unchanged over 6months of storage for the various formulations without isotonicity agents, and for the CPC-containing formulations with non-ionic isotonicity excipients. The chemical content also proved stable after 6months for all 3 temperatures evaluated. In vitro investigation of mucoadhesion was tested using mucin solutions at different concentrations, and the generated negative zeta potential was used as a measure of the interaction. The zeta potential reversed to about -15mV, indicating distinct interaction. The

  15. High-speed simultaneous ion-exclusion/cation-exchange chromatography of anions and cations on a weakly acidic cation-exchange resin column.

    PubMed

    Mori, Masanobu; Tanaka, Kazuhiko; Helaleh, Murad I H; Xu, Qun; Ikedo, Mikaru; Ogura, Yutaka; Sato, Shinji; Hu, Wenzhi; Hasebe, Kiyoshi; Haddad, Paul R

    2003-05-16

    The simultaneous ion-exclusion/cation-exchange separation column packed with a polymethacrylate-based weakly acidic cation-exchange resin of 3 microm particle size was used to achieve the simultaneous high-speed separation of anions and cations (Cl(-), NO3(-), SO4(2-), Na(+), K(+), NH4(+), Ca(2+) and Mg(2+)) commonly found in environmental samples. The high-speed simultaneous separation is based on a combination of the ion-exclusion mechanism for the anions and the cation-exchange mechanism for cations. The complete separation of the anions and cations was achieved in 5 min by elution with 15 mM tartaric acid-2.5 mM 18-crown-6 at a flow-rate of 1.5 ml/min. Detection limits at S/N=3 ranged from 0.36 to 0.68 microM for anions and 0.63-0.99 microM for cations. This method has been applied to the simultaneous determination of anions and cations in several environmental waters with satisfactory results.

  16. Electron spin resonance spectroscopic studies of radical cation reactions

    SciTech Connect

    Dai, S.

    1990-01-01

    A spin Hamiltonian suitable for theoretical analyses of ESR spectra is derived using the general effective Hamiltonian theory in the usual Schroedinger representation. The Permutation Indices method is extended to obtain the dynamic exchange equations used in ESR lineshape simulation. The correlation between [beta]-hydrogen coupling constants and their geometric orientations are derived using a perturbation method. The three electron bond model is extended to rationalize unimolecular rearrangements of radical cations. The ring-closed radical cations of 9,10-octalin oxide and synsesquinorbornene oxide have been characterized by ESR spectroscopy in the CFCl[sub 3] matrix at low temperature. The self-electron-transfer rate constants between the methyl viologen dication and cation have been determined by dynamic ESR lineshape simulations at room temperature in allyl alcohol, water, methanol and propargyl alcohol solvents. The radical cation formed by the radiolytic oxidation of allylamine in Freon matrices at 77 K is the 3-iminiopropyl distonic species(3-iminium-1-propyl radical). The nucleophilic endocylization of the but-3-en-1-ol radical cation to the protonated tetrahydrofuran-3-yl radical was observed in the radiolytic oxidation of but-3-en-1-ol in Freon matrices. ESR studies of the radiolytic oxidation of 1,5-hexdiyne have resulted in characterization the 1,5-hexadiyne radical cation isomerizing to the 1,2,4,5-hexatetraene radical cation. The symmetric (C[sub 2v]) bicyclo[3.3.0]-octa-2,6-diene-4,8-diyl(a bridged 1,4-bishomobenzene species) radical cation is produced by the radiolytic oxidation of semibullvalene in Freon matrices. The ring-opening 3,4-dimethylenecyclobutene radical cation to 1,2,4,5-hexatetraene radical cation was observed in the photolysis of 3,4-dimethylenecyclobutene radical cation. The cyclooctatetraene radical cation generated by radiolytic oxidation photoisomerizes to bicyclo[3.3.0]octa-2,6-diene-4,8-diyl radical cation.

  17. Extensive transduction of nonrepetitive DNA mediated by L1 retrotransposition in cancer genomes

    PubMed Central

    Tubio, Jose M. C.; Martincorena, Inigo; Cooke, Susanna L.; Tojo, Marta; Gundem, Gunes; Pipinikas, Christodoulos P.; Zamora, Jorge; Raine, Keiran; Menzies, Andrew; Roman-Garcia, Pablo; Fullam, Anthony; Gerstung, Moritz; Shlien, Adam; Tarpey, Patrick S.; Papaemmanuil, Elli; Knappskog, Stian; Van Loo, Peter; Ramakrishna, Manasa; Davies, Helen R.; Marshall, John; Wedge, David C.; Teague, Jon W.; Butler, Adam P.; Nik-Zainal, Serena; Alexandrov, Ludmil; Behjati, Sam; Yates, Lucy R.; Bolli, Niccolo; Mudie, Laura; Hardy, Claire; Martin, Sancha; McLaren, Stuart; O'Meara, Sarah; Anderson, Elizabeth; Maddison, Mark; Gamble, Stephen; Foster, Christopher; Warren, Anne Y.; Whitaker, Hayley; Brewer, Daniel; Eeles, Rosalind; Cooper, Colin; Neal, David; Lynch, Andy G.; Visakorpi, Tapio; Isaacs, William B.; Veer, Laura van't; Caldas, Carlos; Desmedt, Christine; Sotiriou, Christos; Aparicio, Sam; Foekens, John A.; Eyfjörd, Jórunn Erla; Lakhani, Sunil R.; Thomas, Gilles; Myklebost, Ola; Span, Paul N.; Børresen-Dale, Anne-Lise; Richardson, Andrea L.; Van de Vijver, Marc; Vincent-Salomon, Anne; Van den Eynden, Gert G.; Flanagan, Adrienne M.; Futreal, P. Andrew; Janes, Sam M.; Bova, G. Steven; Stratton, Michael R.; McDermott, Ultan; Campbell, Peter J.

    2015-01-01

    Long interspersed nuclear element–1 (L1) retrotransposons are mobile repetitive elements that are abundant in the human genome. L1 elements propagate through RNA intermediates. In the germ line, neighboring, nonrepetitive sequences are occasionally mobilized by the L1 machinery, a process called 3′ transduction. Because 3′ transductions are potentially mutagenic, we explored the extent to which they occur somatically during tumorigenesis. Studying cancer genomes from 244 patients, we found that tumors from 53% of the patients had somatic retrotranspositions, of which 24% were 3′ transductions. Fingerprinting of donor L1s revealed that a handful of source L1 elements in a tumor can spawn from tens to hundreds of 3′ transductions, which can themselves seed further retrotranspositions. The activity of individual L1 elements fluctuated during tumor evolution and correlated with L1 promoter hypomethylation. The 3′ transductions disseminated genes, exons, and regulatory elements to new locations, most often to heterochromatic regions of the genome. PMID:25082706

  18. Effect of cell lysates on retroviral transduction efficiency of cells in suspension culture.

    PubMed

    Beauchesne, Pascal R; Bruce, Katherine J; Bowen, Bruce D; Piret, James M

    2010-04-15

    Recombinant retroviruses are effective vectors able to integrate transgenes into the target cell's genome to achieve longer-term expression. This study investigates the effect of cell lysis products, a common cell culture by-product, on the transduction of suspension cells by gammaretroviral vectors. Cell lysates derived from human and murine suspension cell lines significantly increased the transduction of human TF-1 and K-562 cell lines by gibbon ape leukemia virus-pseudotyped retroviral vectors without altering tropism. The transduction efficiency of TF-1 cells increased as a function of lysate concentration and decreased with increasing target cell concentrations. This was adequately predicted using a saturation equation based on the lysed-to-target cell concentration ratio, R, where: Fold increase = 1+Fold_(Max) (R/(K_(L)+R)). Lysate completely masked the effects of fibronectin when the two were added in combination. With protamine sulfate, the transduction efficiency was increased by lysate to 58% from 20% for protamine sulfate alone. Overall, the presence of cell lysate significantly influenced the outcome of the transduction process, either alone or in the presence of protamine sulfate or fibronectin. PMID:20014140

  19. VEGF-A isoforms program differential VEGFR2 signal transduction, trafficking and proteolysis

    PubMed Central

    Fearnley, Gareth W.; Smith, Gina A.; Abdul-Zani, Izma; Yuldasheva, Nadira; Mughal, Nadeem A.; Homer-Vanniasinkam, Shervanthi; Kearney, Mark T.; Zachary, Ian C.; Tomlinson, Darren C.; Harrison, Michael A.; Wheatcroft, Stephen B.; Ponnambalam, Sreenivasan

    2016-01-01

    ABSTRACT Vascular endothelial growth factor A (VEGF-A) binding to the receptor tyrosine kinase VEGFR2 triggers multiple signal transduction pathways, which regulate endothelial cell responses that control vascular development. Multiple isoforms of VEGF-A can elicit differential signal transduction and endothelial responses. However, it is unclear how such cellular responses are controlled by isoform-specific VEGF-A–VEGFR2 complexes. Increasingly, there is the realization that the membrane trafficking of receptor–ligand complexes influences signal transduction and protein turnover. By building on these concepts, our study shows for the first time that three different VEGF-A isoforms (VEGF-A165, VEGF-A121 and VEGF-A145) promote distinct patterns of VEGFR2 endocytosis for delivery into early endosomes. This differential VEGFR2 endocytosis and trafficking is linked to VEGF-A isoform-specific signal transduction events. Disruption of clathrin-dependent endocytosis blocked VEGF-A isoform-specific VEGFR2 activation, signal transduction and caused substantial depletion in membrane-bound VEGFR1 and VEGFR2 levels. Furthermore, such VEGF-A isoforms promoted differential patterns of VEGFR2 ubiquitylation, proteolysis and terminal degradation. Our study now provides novel insights into how different VEGF-A isoforms can bind the same receptor tyrosine kinase and elicit diverse cellular outcomes. PMID:27044325

  20. Superior In vivo Transduction of Human Hepatocytes Using Engineered AAV3 Capsid.

    PubMed

    Vercauteren, Koen; Hoffman, Brad E; Zolotukhin, Irene; Keeler, Geoffrey D; Xiao, Jing W; Basner-Tschakarjan, Etiena; High, Katherine A; Ertl, Hildegund Cj; Rice, Charles M; Srivastava, Arun; de Jong, Ype P; Herzog, Roland W

    2016-06-01

    Adeno-associated viral (AAV) vectors are currently being tested in multiple clinical trials for liver-directed gene transfer to treat the bleeding disorders hemophilia A and B and metabolic disorders. The optimal viral capsid for transduction of human hepatocytes has been under active investigation, but results across various models are inconsistent. We tested in vivo transduction in "humanized" mice. Methods to quantitate percent AAV transduced human and murine hepatocytes in chimeric livers were optimized using flow cytometry and confocal microscopy with image analysis. Distinct transduction efficiencies were noted following peripheral vein administration of a self-complementary vector expressing a gfp reporter gene. An engineered AAV3 capsid with two amino acid changes, S663V+T492V (AAV3-ST), showed best efficiency for human hepatocytes (~3-times, ~8-times, and ~80-times higher than for AAV9, AAV8, and AAV5, respectively). AAV5, 8, and 9 were more efficient in transducing murine than human hepatocytes. AAV8 yielded the highest transduction rate of murine hepatocytes, which was 19-times higher than that for human hepatocytes. In summary, our data show substantial differences among AAV serotypes in transduction of human and mouse hepatocytes, are the first to report on AAV5 in humanized mice, and support the use of AAV3-based vectors for human liver gene transfer.

  1. Analysis of nitrated proteins in Saccharomyces cerevisiae involved in mating signal transduction.

    PubMed

    Kang, Jeong Won; Lee, Na Young; Cho, Kyung-Cho; Lee, Min Young; Choi, Do-Young; Park, Sang-Hyun; Kim, Kwang Pyo

    2015-01-01

    Protein tyrosine nitration (PTN) is a PTM that regulates signal transduction and inflammatory responses, and is related to neurodegenerative and cardiovascular diseases. The cellular function of PTN remains unclear because the low stoichiometry of PTN limits the identification and quantification of nitrated peptides. Effective enrichment is an important aspect of PTN analysis. In this study, we analyzed the in vivo nitroproteome elicited by mating signal transduction in Saccharomyces cerevisiae using a novel chemical enrichment method followed by LC-MS/MS. Nitroproteome profiling successfully identified changes in the nitration states of 14 proteins during mating signal transduction in S. cerevisiae, making this the first reported in vivo nitroproteome in yeast. We investigated the biological functions of these nitroproteins and their relationships to mating signal transduction in S. cerevisiae using a protein-protein interaction network. Our results suggest that PTN and denitration may be involved in nonreactive nitrogen species-mediated signal transduction and can provide clues for understanding the functional roles of PTN in vivo.

  2. The SUMOylation Pathway Restricts Gene Transduction by Adeno-Associated Viruses.

    PubMed

    Hölscher, Christina; Sonntag, Florian; Henrich, Katharina; Chen, Qingxin; Beneke, Jürgen; Matula, Petr; Rohr, Karl; Kaderali, Lars; Beil, Nina; Erfle, Holger; Kleinschmidt, Jürgen A; Müller, Martin

    2015-12-01

    Adeno-associated viruses are members of the genus dependoviruses of the parvoviridae family. AAV vectors are considered promising vectors for gene therapy and genetic vaccination as they can be easily produced, are highly stable and non-pathogenic. Nevertheless, transduction of cells in vitro and in vivo by AAV in the absence of a helper virus is comparatively inefficient requiring high multiplicity of infection. Several bottlenecks for AAV transduction have previously been described, including release from endosomes, nuclear transport and conversion of the single stranded DNA into a double stranded molecule. We hypothesized that the bottlenecks in AAV transduction are, in part, due to the presence of host cell restriction factors acting directly or indirectly on the AAV-mediated gene transduction. In order to identify such factors we performed a whole genome siRNA screen which identified a number of putative genes interfering with AAV gene transduction. A number of factors, yielding the highest scores, were identified as members of the SUMOylation pathway. We identified Ubc9, the E2 conjugating enzyme as well as Sae1 and Sae2, enzymes responsible for activating E1, as factors involved in restricting AAV. The restriction effect, mediated by these factors, was validated and reproduced independently. Our data indicate that SUMOylation targets entry of AAV capsids and not downstream processes of uncoating, including DNA single strand conversion or DNA damage signaling. We suggest that transiently targeting SUMOylation will enhance application of AAV in vitro and in vivo.

  3. Incorporation of photosenzitizer hypericin into synthetic lipid-based nano-particles for drug delivery and large unilamellar vesicles with different content of cholesterol

    NASA Astrophysics Data System (ADS)

    Joniova, Jaroslava; Blascakova, Ludmila; Jancura, Daniel; Nadova, Zuzana; Sureau, Franck; Miskovsky, Pavol

    2014-08-01

    Low-density lipoproteins (LDL) and high-density lipoproteins (HDL) are attractive natural occurring vehicles for drug delivery and targeting to cancer tissues. The capacity of both types of the lipoproteins to bind hydrophobic drugs and their functionality as drug carriers have been examined in several studies and it has been also shown that mixing of anticancer drugs with LDL or HDL before administration led to an increase of cytotoxic effects of the drugs in the comparison when the drugs were administered alone. However, a difficult isolation of the lipoproteins in large quantity from a biological organism as well as a variability of the composition and size of these molecules makes practical application of LDL and HDL as drug delivery systems quite complicated. Synthetic LDL and HDL and large unilamellar vesicles (LUV) are potentially suitable candidates to substitute the native lipoproteins for targeted and effective drug delivery. In this work, we have studied process of an association of potent photosensitizer hypericin (Hyp) with synthetic lipid-based nano-particles (sLNP) and large unilamellar vesicles (LUV) containing various amount of cholesterol. Cholesterol is one of the main components of both LDL and HDL particles and its presence in biological membranes is known to be a determining factor for membrane properties. It was found that the behavior of Hyp incorporation into sLNP particles with diameter ca ~ 90 nm is qualitatively very similar to that of Hyp incorporation into LDL (diameter ca. 22 nm) and these particles are able to enter U-87 MG cells by endocytosis. The presence of cholesterol in LUV influences the capacity of these vesicles to incorporate Hyp into their structure.

  4. Toward the establishment of standardized in vitro tests for lipid-based formulations, part 6: effects of varying pancreatin and calcium levels.

    PubMed

    Sassene, Philip; Kleberg, Karen; Williams, Hywel D; Bakala-N'Goma, Jean-Claude; Carrière, Frédéric; Calderone, Marilyn; Jannin, Vincent; Igonin, Annabel; Partheil, Anette; Marchaud, Delphine; Jule, Eduardo; Vertommen, Jan; Maio, Mario; Blundell, Ross; Benameur, Hassan; Porter, Christopher J H; Pouton, Colin W; Müllertz, Anette

    2014-11-01

    The impact of pancreatin and calcium addition on a wide array of lipid-based formulations (LBFs) during in vitro lipolysis, with regard to digestion rates and distribution of the model drug danazol, was investigated. Pancreatin primarily affected the extent of digestion, leaving drug distribution somewhat unaffected. Calcium only affected the extent of digestion slightly but had a major influence on drug distribution, with more drug precipitating at higher calcium levels. This is likely to be caused by a combination of removal of lipolysis products from solution by the formation of calcium soaps and calcium precipitating with bile acids, events known to reduce the solubilizing capacity of LBFs dispersed in biorelevant media. Further, during the digestion of hydrophilic LBFs, like IIIA-LC, the un-ionized-ionized ratio of free fatty acids (FFA) remained unchanged at physiological calcium levels. This makes the titration curves at pH 6.5 representable for digestion. However, caution should be taken when interpreting lipolysis curves of lipophilic LBFs, like I-LC, at pH 6.5, at physiological levels of calcium (1.4 mM); un-ionized-ionized ratio of FFA might change during digestion, rendering the lipolysis curve at pH 6.5 non-representable for the total digestion. The ratio of un-ionized-ionized FFAs can be maintained during digestion by applying non-physiological levels of calcium, resulting in a modified drug distribution with increased drug precipitation. However, as the main objective of the in vitro digestion model is to evaluate drug distribution, which is believed to have an impact on bioavailability in vivo, a physiological level (1.4 mM) of calcium is preferred. PMID:25274609

  5. Responsive feeding and child interest in food vary when rural Malawian children are fed lipid-based nutrient supplements or local complementary food.

    PubMed

    Flax, Valerie L; Mäkinen, Samppa; Ashorn, Ulla; Cheung, Yin Bun; Maleta, Kenneth; Ashorn, Per; Bentley, Margaret E

    2013-07-01

    Caregiver and child behaviours during feeding have been used to measure responsiveness, which has been recognised as important for child growth and development. The aims of this study were to understand how caregiver and child behaviours differ when feeding lipid-based nutrient supplements (LNS) vs. local complementary food and to detect associations between behaviours and child interest in food. Sixteen moderately underweight 6-17-month-old Malawian children receiving 50 g/day of supplementary LNS for 12 weeks were videotaped during LNS (n = 32) and local complementary feeding (n = 28) episodes. Behaviours were coded at the level of the intended bite (1674 total bites). The analysis used regression models adjusted for within-subject correlation. Caregivers were less likely to allow children to self-feed and more likely to use physical pressure during LNS vs. complementary food bites. Positive caregiver verbalization was infrequent and did not differ by type of food. Higher odds of accepting a bite were associated with the bite containing LNS, odds ratio (OR) 3.05; 90% confidence interval (CI) (1.98, 4.71), the child self-feeding, OR 5.70; 90% CI (2.77, 11.69), and positive caregiver verbalization, OR 2.46; 90% CI (1.26, 4.80), while lower odds of acceptance were associated with negative child verbalization during feeding, OR 0.27; 90% CI (0.17, 0.42). In this sample, caregivers used more responsive feeding practices during bites of local complementary food and were more controlling when feeding LNS. Responsive caregiver behaviours predicted child acceptance of food. These results could be used to design interventions in Malawi to improve responsive feeding practices in general and during LNS use.

  6. Linear growth increased in young children in an urban slum of Haiti: a randomized controlled trial of a lipid-based nutrient supplement123

    PubMed Central

    Iannotti, Lora L; Dulience, Sherlie Jean Louis; Green, Jamie; Joseph, Saminetha; François, Judith; Anténor, Marie-Lucie; Lesorogol, Carolyn; Mounce, Jacqueline; Nickerson, Nathan M

    2014-01-01

    Background: Haiti has experienced rapid urbanization that has exacerbated poverty and undernutrition in large slum areas. Stunting affects 1 in 5 young children. Objective: We aimed to test the efficacy of a daily lipid-based nutrient supplement (LNS) for increased linear growth in young children. Design: Healthy, singleton infants aged 6–11 mo (n = 589) were recruited from an urban slum of Cap Haitien and randomly assigned to receive: 1) a control; 2) a 3-mo LNS; or 3) a 6-mo LNS. The LNS provided 108 kcal and other nutrients including vitamin A, vitamin B-12, iron, and zinc at ≥80% of the recommended amounts. Infants were followed monthly on growth, morbidity, and developmental outcomes over a 6-mo intervention period and at one additional time point 6 mo postintervention to assess sustained effects. The Bonferroni multiple comparisons test was applied, and generalized least-squares (GLS) regressions with mixed effects was used to examine impacts longitudinally. Results: Baseline characteristics did not differ by trial arm except for a higher mean age in the 6-mo LNS group. GLS modeling showed LNS supplementation for 6 mo significantly increased the length-for-age z score (±SE) by 0.13 ± 0.05 and the weight-for-age z score by 0.12 ± 0.02 compared with in the control group after adjustment for child age (P < 0.001). The effects were sustained 6 mo postintervention. Morbidity and developmental outcomes did not differ by trial arm. Conclusion: A low-energy, fortified product improved the linear growth of young children in this urban setting. The trial was registered at clinicaltrials.gov as NCT01552512. PMID:24225356

  7. Efficient protection and transfection of small interfering RNA by cationic shell-crosslinked knedel-like nanoparticles.

    PubMed

    Shen, Yuefei; Fang, Huafeng; Zhang, Ke; Shrestha, Ritu; Wooley, Karen L; Taylor, John-Stephen A

    2013-04-01

    Despite the great potential of small interfering RNA (siRNA) as a therapeutic agent, progress in this area has been hampered by a lack of efficient biocompatible transfection agents. Recently, cationic shell-crosslinked knedel-like nanoparticles (cSCKs) were found to possess lower cytotoxicity and better transfection ability for phosphorothioate ODNs and plasmid DNA than the commonly used cationic lipid-based agent Lipofectamine. To determine the usefulness of cSCKs for siRNA transfection, a small library of cSCKs with varying percentage of primary and tertiary amines was assessed for its ability to bind to siRNA, inhibit siRNA degradation in human serum, and to transfect HeLa and mouse macrophage cell lines. The silencing efficiency in HeLa cells was greatest with the cSCK with 100% primary amines (pa100) as determined by their viability following transfection with cytotoxic and non-cytotoxic siRNAs. cSCK-pa100 showed greater silencing efficiency than Lipofectamine 2000 in the HeLa cells, as well in 293T and human bronchial epithelial (HEK) cells, but was comparable in human bronchial epithelial (BEAS-2B) cells and human mammary epithelial (MCF10a) cells. cSCK-pa100 also showed greater silencing of iNOS expression than Lipofectamine 2000 in a mouse macrophage cell line, and provided greater protection from serum degradation, demonstrating its potential usefulness as an siRNA transfection agent. The siRNA silencing of iNOS at lower concentrations of siRNA could be enhanced by complexation with the fusogenic GALA peptide, which was shown to enhance endosomal escape following uptake.

  8. Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism

    PubMed Central

    Boughlala, Zakaria; Fonseca Guerra, Célia

    2016-01-01

    Abstract We have analyzed the structure and bonding of gas‐phase Cl−X and [HCl−X]+ complexes for X+= H+, CH3 +, Li+, and Na+, using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl− and HCl for the various cations. The Cl−X bond becomes longer and weaker along X+ = H+, CH3 +, Li+, and Na+. Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence of solvent) alkali metal cation affinities (AMCA) and how this compares with and differs from those of the proton affinity (PA) and methyl cation affinity (MCA). Our analyses are based on Kohn–Sham molecular orbital (KS‐MO) theory in combination with a quantitative energy decomposition analysis (EDA) that pinpoints the importance of the different features in the bonding mechanism. Orbital overlap appears to play an important role in determining the trend in cation affinities. PMID:27551660

  9. Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism.

    PubMed

    Boughlala, Zakaria; Fonseca Guerra, Célia; Bickelhaupt, F Matthias

    2016-06-01

    We have analyzed the structure and bonding of gas-phase Cl-X and [HCl-X](+) complexes for X(+)= H(+), CH3 (+), Li(+), and Na(+), using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl(-) and HCl for the various cations. The Cl-X bond becomes longer and weaker along X(+) = H(+), CH3 (+), Li(+), and Na(+). Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence of solvent) alkali metal cation affinities (AMCA) and how this compares with and differs from those of the proton affinity (PA) and methyl cation affinity (MCA). Our analyses are based on Kohn-Sham molecular orbital (KS-MO) theory in combination with a quantitative energy decomposition analysis (EDA) that pinpoints the importance of the different features in the bonding mechanism. Orbital overlap appears to play an important role in determining the trend in cation affinities. PMID:27551660

  10. Photodissociation of Cerium Oxide Nanocluster Cations.

    PubMed

    Akin, S T; Ard, S G; Dye, B E; Schaefer, H F; Duncan, M A

    2016-04-21

    Cerium oxide cluster cations, CexOy(+), are produced via laser vaporization in a pulsed nozzle source and detected with time-of-flight mass spectrometry. The mass spectrum displays a strongly preferred oxide stoichiometry for each cluster with a specific number of metal atoms x, with x ≤ y. Specifically, the most prominent clusters correspond to the formula CeO(CeO2)n(+). The cluster cations are mass selected and photodissociated with a Nd:YAG laser at either 532 or 355 nm. The prominent clusters dissociate to produce smaller species also having a similar CeO(CeO2)n(+) formula, always with apparent leaving groups of (CeO2). The production of CeO(CeO2)n(+) from the dissociation of many cluster sizes establishes the relative stability of these clusters. Furthermore, the consistent loss of neutral CeO2 shows that the smallest neutral clusters adopt the same oxidation state (IV) as the most common form of bulk cerium oxide. Clusters with higher oxygen content than the CeO(CeO2)n(+) masses are present with much lower abundance. These species dissociate by the loss of O2, leaving surviving clusters with the CeO(CeO2)n(+) formula. Density functional theory calculations on these clusters suggest structures composed of stable CeO(CeO2)n(+) cores with excess oxygen bound to the surface as a superoxide unit (O2(-)). PMID:27035210

  11. Interaction of Hyaluronan with Cationic Nanoparticles.

    PubMed

    Bano, Fouzia; Carril, Mónica; Di Gianvincenzo, Paolo; Richter, Ralf P

    2015-08-01

    The polysaccharide hyaluronan (HA) is a main component of peri- and extracellular matrix, and an attractive molecule for materials design in tissue engineering and nanomedicine. Here, we study the morphology of complexes that form upon interaction of nanometer-sized amine-coated gold particles with this anionic, linear, and regular biopolymer in solution and grafted to a surface. We find that cationic nanoparticles (NPs) have profound effects on HA morphology on the molecular and supramolecular scale. Quartz crystal microbalance (QCM-D) shows that depending on their relative abundance, cationic NPs promote either strong compaction or swelling of films of surface-grafted HA polymers (HA brushes). Transmission electron and atomic force microscopy reveal that the NPs do also give rise to complexes of distinct morphologies-compact nanoscopic spheres and extended microscopic fibers-upon interaction with HA polymers in solution. In particular, stable and hydrated spherical complexes of single HA polymers with NPs can be prepared when balancing the ionizable groups on HA and NPs. The observed self-assembly phenomena could be useful for the design of drug delivery vehicles and a better understanding of the reorganization of HA-rich synthetic or biological matrices. PMID:26146006

  12. Antibacterial Activity of Geminized Amphiphilic Cationic Homopolymers.

    PubMed

    Wang, Hui; Shi, Xuefeng; Yu, Danfeng; Zhang, Jian; Yang, Guang; Cui, Yingxian; Sun, Keji; Wang, Jinben; Yan, Haike

    2015-12-22

    The current study is aimed at investigating the effect of cationic charge density and hydrophobicity on the antibacterial and hemolytic activities. Two kinds of cationic surfmers, containing single or double hydrophobic tails (octyl chains or benzyl groups), and the corresponding homopolymers were synthesized. The antimicrobial activity of these candidate antibacterials was studied by microbial growth inhibition assays against Escherichia coli, and hemolysis activity was carried out using human red blood cells. It was interestingly found that the homopolymers were much more effective in antibacterial property than their corresponding monomers. Furthermore, the geminized homopolymers had significantly higher antibacterial activity than that of their counterparts but with single amphiphilic side chains in each repeated unit. Geminized homopolymers, with high positive charge density and moderate hydrophobicity (such as benzyl groups), combine both advantages of efficient antibacterial property and prominently high selectivity. To further explain the antibacterial performance of the novel polymer series, the molecular interaction mechanism is proposed according to experimental data which shows that these specimens are likely to kill microbes by disrupting bacterial membranes, leading them unlikely to induce resistance.

  13. Transition-Metal Hydride Radical Cations.

    PubMed

    Hu, Yue; Shaw, Anthony P; Estes, Deven P; Norton, Jack R

    2016-08-10

    Transition-metal hydride radical cations (TMHRCs) are involved in a variety of chemical and biochemical reactions, making a more thorough understanding of their properties essential for explaining observed reactivity and for the eventual development of new applications. Generally, these species may be treated as the ones formed by one-electron oxidation of diamagnetic analogues that are neutral or cationic. Despite the importance of TMHRCs, the generally sensitive nature of these complexes has hindered their development. However, over the last four decades, many more TMHRCs have been synthesized, characterized, isolated, or hypothesized as reaction intermediates. This comprehensive review focuses on experimental studies of TMHRCs reported through the year 2014, with an emphasis on isolated and observed species. The methods used for the generation or synthesis of TMHRCs are surveyed, followed by a discussion about the stability of these complexes. The fundamental properties of TMHRCs, especially those pertaining to the M-H bond, are described, followed by a detailed treatment of decomposition pathways. Finally, reactions involving TMHRCs as intermediates are described. PMID:26828562

  14. Electrostatics of DNA complexes with cationic lipids

    NASA Astrophysics Data System (ADS)

    Cherstvy, Andrey

    2007-03-01

    We present the exact solutions of the linear Poisson-Boltzmann theory for several problems relevant to electrostatics of DNA complexes with cationic lipids. We calculate the electrostatic potential and energy for lamellar and inverted hexagonal phases, concentrating on the effects of water-membrane dielectric boundaries. Our results for the complex energy agree qualitatively well with the known numerical solutions of the nonlinear Poisson-Boltzmann equation. Using the solution for the lamellar phase, we calculate its compressibility modulus and compare our findings with experimental data available suggesting a new scaling dependence on DNA-DNA separations in the complex. Also, we treat analytically charge-charge electrostatic interactions across, along, and in between two low-dielectric membranes. We obtain an estimate for the strength of electrostatic interactions of 1D DNA smectic layers across a lipid membrane. We discuss also some aspects of 2D DNA condensation and DNA-DNA attraction in DNA-lipid lamellar phase in the presence of di- and tri-valent cations and analyze the equilibrium intermolecular separations using the recently developed theory of electrostatic interactions of DNA helical charge motifs.

  15. Interaction of Hyaluronan with Cationic Nanoparticles.

    PubMed

    Bano, Fouzia; Carril, Mónica; Di Gianvincenzo, Paolo; Richter, Ralf P

    2015-08-01

    The polysaccharide hyaluronan (HA) is a main component of peri- and extracellular matrix, and an attractive molecule for materials design in tissue engineering and nanomedicine. Here, we study the morphology of complexes that form upon interaction of nanometer-sized amine-coated gold particles with this anionic, linear, and regular biopolymer in solution and grafted to a surface. We find that cationic nanoparticles (NPs) have profound effects on HA morphology on the molecular and supramolecular scale. Quartz crystal microbalance (QCM-D) shows that depending on their relative abundance, cationic NPs promote either strong compaction or swelling of films of surface-grafted HA polymers (HA brushes). Transmission electron and atomic force microscopy reveal that the NPs do also give rise to complexes of distinct morphologies-compact nanoscopic spheres and extended microscopic fibers-upon interaction with HA polymers in solution. In particular, stable and hydrated spherical complexes of single HA polymers with NPs can be prepared when balancing the ionizable groups on HA and NPs. The observed self-assembly phenomena could be useful for the design of drug delivery vehicles and a better understanding of the reorganization of HA-rich synthetic or biological matrices.

  16. Cation adsorption on manganese dioxide impregnated fibers

    SciTech Connect

    Fisher, S. ); Stahel, E.P. )

    1992-12-01

    Complete removal of radioactive cations by standard mixed bed ion exchange resins is sometimes not achieved in liquid radwaste systems. Based on a literature survey, acrylic fibers impregnated with manganese dioxide were chosen as a media warranting study of their ability to adsorb the cations present in radwaste systems in the hope of improving performance of such treatment processes. A system to produce impregnated fiber with a heavy MnO[sub 2] loading was designed, constructed, and operated. The system produced fiber at an average fiber loading of 22.5 percent MnO[sub 2] by weight. Leaching tests made on the MnO[sub 2] fiber exhibited no signs of soluble manganese, insoluble MnO[sub 2], acrylonitrile leaching or fiber loss. Laboratory testing has been performed on the adsorption of calcium, cadmium, cesium, cobalt, iron, and manganese on MnO[sub 2] impregnated fiber. Removal of metals from solution was measured at levels specific for each metal tested. The removal efficiency when they were present in combination was also evaluated.

  17. Biomimetic CO2 Sequestration: Cation Sources

    NASA Astrophysics Data System (ADS)

    Bond, G. M.; Stringer, J.; Medina, M.; McPherson, B.; Wellman, T.; Lichtner, P. C.; Abel, A.

    2001-12-01

    Conversion of CO2 to solid carbonates offers the possibility of a safe, stable product for long-term carbon sequestration. Naturally occurring carbonate minerals already comprise a massive carbon reservoir that has existed for millions of years. Large quantities of these carbonate minerals are of biogenic origin. We have demonstrated proof of principle for a novel biomimetic approach to carbon sequestration, which uses a natural catalyst, the enzyme carbonic anhydrase, to accelerate the formation of bicarbonate ions in aqueous solution. In the presence of suitable cations, this can then be precipitated out in carbonate form. One of the issues we are now addressing is the selection of suitable sources of cations. Along with seawater, and waste brines from desalination operations, brines from deep saline aquifers offer an attractive possibility. In this context, it is important to understand the effects of brine flow on geologic media, both during brine extraction and during possible reinjection of bicarbonate-enriched brines. We have used numerical simulations to evaluate and compare the effects of supercritical CO2 flow to the effects of bicarbonate solution flow on geologic media. Specifically, we examined diagenetic changes and time-scales of these changes associated with flow of the two different fluids. For these simulations we assembled and applied a model of reactive transport, including coupled groundwater flow, heat flow, and relevant geochemical reactions. Simulations have been conducted for laboratory-scale models, with the intention that these results will be used for calibration of and upscaling to larger-scale hydrogeologic models.

  18. Ceramic Spheres From Cation Exchange Beads

    NASA Technical Reports Server (NTRS)

    Dynys, F. W.

    2003-01-01

    Porous ZrO2 and hollow TiO2 spheres were synthesized from a strong acid cation exchange resin. Spherical cation exchange beads, polystyrene based polymer, were used as a morphological-directing template. Aqueous ion exchange reaction was used to chemically bind (ZrO)(2+) ions to the polystyrene structure. The pyrolysis of the polystyrene at 600 C produces porous ZrO2 spheres with a surface area of 24 sq m/g with a mean sphere size of 42 microns. Hollow TiO2 spheres were synthesized by using the beads as a micro-reactor. A direct surface reaction - between titanium isopropoxide and the resin beads forms a hydrous TiO2 shell around the polystyrene core. The pyrolysis of the polystyrene core at 600 C produces hollow anatase spheres with a surface area of 42 sq m/g with a mean sphere size of 38 microns. The formation of ceramic spheres was studied by XRD, SEM and B.E.T. nitrogen adsorption measurements.

  19. Transition-Metal Hydride Radical Cations.

    PubMed

    Hu, Yue; Shaw, Anthony P; Estes, Deven P; Norton, Jack R

    2016-08-10

    Transition-metal hydride radical cations (TMHRCs) are involved in a variety of chemical and biochemical reactions, making a more thorough understanding of their properties essential for explaining observed reactivity and for the eventual development of new applications. Generally, these species may be treated as the ones formed by one-electron oxidation of diamagnetic analogues that are neutral or cationic. Despite the importance of TMHRCs, the generally sensitive nature of these complexes has hindered their development. However, over the last four decades, many more TMHRCs have been synthesized, characterized, isolated, or hypothesized as reaction intermediates. This comprehensive review focuses on experimental studies of TMHRCs reported through the year 2014, with an emphasis on isolated and observed species. The methods used for the generation or synthesis of TMHRCs are surveyed, followed by a discussion about the stability of these complexes. The fundamental properties of TMHRCs, especially those pertaining to the M-H bond, are described, followed by a detailed treatment of decomposition pathways. Finally, reactions involving TMHRCs as intermediates are described.

  20. Cationic Antimicrobial Polymers and Their Assemblies

    PubMed Central

    Carmona-Ribeiro, Ana Maria; de Melo Carrasco, Letícia Dias

    2013-01-01

    Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs). The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications. PMID:23665898

  1. Anionic polymers for decreased toxicity and enhanced in vivo delivery of siRNA complexed with cationic liposomes.

    PubMed

    Schlegel, Anne; Largeau, Céline; Bigey, Pascal; Bessodes, Michel; Lebozec, Kristell; Scherman, Daniel; Escriou, Virginie

    2011-06-30

    We recently reported a cationic lipid-based vector of siRNA, termed siRNA lipoplex that was very efficient in specific gene silencing, both in cell culture and in mouse disease models. To be more efficient, this vector included the addition of a plasmid DNA as an anionic "cargo." Although this plasmid DNA was devoid of any eukaryotic expression cassette, we decided to replace it by an anionic polymer that would be more acceptable for clinical applications. We identified seven anionic polymers, regarded as non-toxic, biodegradable, of various characteristics and nature. The addition of polymers to siRNA lipoplexes led to the formation of particles with similar characteristics to crude siRNA lipoplexes, decreased cellular toxicity and variable in vitro gene silencing efficiency depending on the type of polymer used. Upon i.v. injection in mice, siRNA lipoplexes prepared with the best polymer, polyglutamate, led to significantly increased recovery of siRNA in liver and lung compared with lipoplexes without polymer.

  2. Ground state of naphthyl cation: Singlet or triplet?

    SciTech Connect

    Dutta, Achintya Kumar; Vaval, Nayana Pal, Sourav; Manohar, Prashant U.

    2014-03-21

    We present a benchmark theoretical investigation on the electronic structure and singlet-triplet(S-T) gap of 1- and 2-naphthyl cations using the CCSD(T) method. Our calculations reveal that the ground states of both the naphthyl cations are singlet, contrary to the results obtained by DFT/B3LYP calculations reported in previous theoretical studies. However, the triplet states obtained in the two structural isomers of naphthyl cation are completely different. The triplet state in 1-naphthyl cation is (π,σ) type, whereas in 2-naphthyl cation it is (σ,σ{sup ′}) type. The S-T gaps in naphthyl cations and the relative stability ordering of the singlet and the triplet states are highly sensitive to the basis-set quality as well as level of correlation, and demand for inclusion of perturbative triples in the coupled-cluster ansatz.

  3. Stapled endosome disrupting alginate particles for cytosolic delivery of cations.

    PubMed

    Acharya, Abhinav P; Little, Steven R

    2015-01-01

    Divalent cations, the most prevalent minerals in the body, are responsible for a wide variety of cellular functions including signaling, proliferation, differentiation and cell death, and therefore their transmembrane transportation is tightly regulated. Despite the importance of divalent cations in cell activity, there are currently no intracellular delivery methods for divalent cations or modulation of intracellular levels of minerals. Here, we describe endosome disrupting alginate nanoparticles termed Alginoketals, which can deliver divalent cations to the cytosol of the cells. Alginoketals are generated by crosslinking alginic acid with endosome disrupting ketals, and using divalent cations as the stapling or binding agent. We show that Alginoketals were able to deliver copper (II) in the cytosol of the cancer cells thereby disrupting copper homeostasis and inducing cell death via accumulation of hydrogen peroxide. Alginoketal-copper (II)-based particles act as superoxide dismutase mimics and are the first class of divalent cation delivery vehicles, with potential application in cancer therapy, regenerative medicine and drug delivery.

  4. Plant rhamnogalacturonan II complexation of heavy metal cations

    DOEpatents

    O`Neill, M.A.; Pellerin, P.J.M.; Warrenfeltz, D.; Vidal, S.; Darvill, A.G.; Albersheim, P.

    1999-03-02

    The present invention provides rhamnogalacturonan-II (RG-II) and relates to its ability to complex specific multivalent heavy metal cations. In the presence of boric acid, RG-II monomers form dimers that are cross-linked by a borate ester. The yield of such borate ester cross-linked dimers of RG-II is enhanced in the presence of specific heavy metal cations. The present invention further relates to the utility of RG-II in assays for the detection of specific heavy metal contamination; as a reagent useful in the removal of specific heavy metal cations contaminating foods and liquids, for example, fish, wines, etc.; as a pharmaceutical composition useful as an antidote in specific heavy metal cation poisoning; as a treatment for the detoxification of specific heavy metal cations from blood and/or tissues; and in a method of remediation of waters and soils contaminated with specific heavy metal cations. 15 figs.

  5. Influence of interlayer cations on organic intercalation of montmorillonite.

    PubMed

    Wu, Limei; Liao, Libing; Lv, Guocheng

    2015-09-15

    The influence of the types of interlayer cations on organic intercalation of montmorillonite (Mt) was studied in this paper. The distribution of Na(+), K(+), Mg(2+), Ca(2+) and Fe(3+) in montmorillonite interlayer, their interaction with structure layers and the effect of interlayer cations on the basal spacing of Mt, the amount of binding water for different interlayer cations and the binding force between them were investigated systematically. 1-Hexadecy1-3-methylimidazolium chloride monohydrate (C16mimCl) was intercalated into montmorillonites with different interlayer cations. The influence of interlayer cations on organic intercalation was investigated. Molecular dynamics (MD) modeling was used to speculate the interlayer microstructures of the organically intercalated Mt with different interlayer cations. These simulations help to predict the microstructure of organo-Mt and guide their relevant engineering applications. PMID:26001131

  6. Plant rhamnogalacturonan II complexation of heavy metal cations

    DOEpatents

    O'Neill, Malcolm A.; Pellerin, Patrice J. M.; Warrenfeltz, Dennis; Vidal, Stephane; Darvill, Alan G.; Albersheim, Peter

    1999-01-01

    The present invention provides rhamnogalacturonan-II (RG-II) and relates to its ability to complex specific multivalent heavy metal cations. In the presence of boric acid, RG-II monomers form dimers that are cross-linked by a borate ester. The yield of such borate ester cross-linked dimers of RG-II is enhanced in the presence of specific heavy metal cations. The present invention further relates to the utility of RG-II in assays for the detection of specific heavy metal contamination; as a reagent useful in the removal of specific heavy metal cations contaminating foods and liquids, for example, fish, wines, etc.; as a pharmaceutical composition useful as an antidote in specific heavy metal cation poisoning; as a treatment for the detoxification of specific heavy metal cations from blood and/or tissues; and in a method of remediation of waters and soils contaminated with specific heavy metal cations.

  7. Mechanical regulation of a molecular clutch defines force transmission and transduction in response to matrix rigidity.

    PubMed

    Elosegui-Artola, Alberto; Oria, Roger; Chen, Yunfeng; Kosmalska, Anita; Pérez-González, Carlos; Castro, Natalia; Zhu, Cheng; Trepat, Xavier; Roca-Cusachs, Pere

    2016-05-01

    Cell function depends on tissue rigidity, which cells probe by applying and transmitting forces to their extracellular matrix, and then transducing them into biochemical signals. Here we show that in response to matrix rigidity and density, force transmission and transduction are explained by the mechanical properties of the actin-talin-integrin-fibronectin clutch. We demonstrate that force transmission is regulated by a dynamic clutch mechanism, which unveils its fundamental biphasic force/rigidity relationship on talin depletion. Force transduction is triggered by talin unfolding above a stiffness threshold. Below this threshold, integrins unbind and release force before talin can unfold. Above the threshold, talin unfolds and binds to vinculin, leading to adhesion growth and YAP nuclear translocation. Matrix density, myosin contractility, integrin ligation and talin mechanical stability differently and nonlinearly regulate both force transmission and the transduction threshold. In all cases, coupling of talin unfolding dynamics to a theoretical clutch model quantitatively predicts cell response. PMID:27065098

  8. Peach (Prunus persica) extract inhibits angiotensin II-induced signal transduction in vascular smooth muscle cells.

    PubMed

    Kono, Ryohei; Okuno, Yoshiharu; Nakamura, Misa; Inada, Ken-ichi; Tokuda, Akihiko; Yamashita, Miki; Hidaka, Ryu; Utsunomiya, Hirotoshi

    2013-08-15

    Angiotensin II (Ang II) is a vasoactive hormone that has been implicated in cardiovascular diseases. Here, the effect of peach, Prunus persica L. Batsch, pulp extract on Ang II-induced intracellular Ca(2+) mobilization, reactive oxygen species (ROS) production and signal transduction events in cultured vascular smooth muscle cells (VSMCs) was investigated. Pretreatment of peach ethyl acetate extract inhibited Ang II-induced intracellular Ca(2+) elevation in VSMCs. Furthermore, Ang II-induced ROS generation, essential for signal transduction events, was diminished by the peach ethyl acetate extract. The peach ethyl acetate extract also attenuated the Ang II-induced phosphorylation of epidermal growth factor receptor and myosin phosphatase target subunit 1, both of which are associated with atherosclerosis and hypertension. These results suggest that peach ethyl acetate extract may have clinical potential for preventing cardiovascular diseases by interfering with Ang II-induced intracellular Ca(2+) elevation, the generation of ROS, and then blocking signal transduction events.

  9. Analysis of a signal transduction pathway involved in leaf epidermis differentiation.

    SciTech Connect

    Philip W. Becraft

    2005-05-23

    The major objective of this study was to identify and analyze signal transduction factors that function with the CR4 receptor kinase. We pursued this analysis in Arabidopsis. Analysis of other members of the ACR4 related receptor (CRR) family produced biochemical evidence consistent with some of them functioning in ACR4 signal transduction. Yeast 2-hybrid identified six proteins that interact with the cytoplasmic domain of ACR4, representing putative downstream signal transduction components. The interactions for all 6 proteins were verified by in vitro pull down assays. Five of the interacting proteins were phosphorylated by ACR4. We also identified candidate interactors with the extracellular TNFR domain. We hypothesize this may be the ligand binding domain for ACR4. In one approach, yeast 2-hybrid was again used and five candidate proteins identified. Nine additional candidates were identified in a genome wide scan of Arabidopsis amino acid sequences that threaded onto the TNF structure.

  10. Transduction of a freshwater microbial community by a new Pseudomonas aeruginosa generalized transducing phage, UT1.

    PubMed

    Ripp, S; Ogunseitan, O A; Miller, R V

    1994-04-01

    A pseudolysogenic, generalized transducing bacteriophage, UT1, isolated from a natural freshwater habitat, is capable of mediating the transfer of both chromosomal and plasmid DNA between strains of Pseudomonas aeruginosa. Several chromosomal alleles from three different P. aeruginosa strains were found to transduce at frequencies from 10(-8) to 10(-10) transductants per PFU at multiplicities of infection (MOI) between 0.1 and 1. Transduction frequencies of certain alleles increased up to 1000-fold as MOIs were decreased to 0.01. UT1 is also capable of transducing plasmid DNA to indigenous populations of microorganisms in natural lake-water environments. Data obtained in this study suggest that environmentally endemic bacteriophages such as UT1 are formidable transducers of naturally occurring microbial communities. It should be possible to develop model systems to test transduction in freshwater environments using components derived exclusively from these environments.

  11. Solvent-dependent cation exchange in metal-organic frameworks.

    PubMed

    Brozek, Carl K; Bellarosa, Luca; Soejima, Tomohiro; Clark, Talia V; López, Núria; Dincă, Mircea

    2014-06-01

    We investigated which factors govern the critical steps of cation exchange in metal-organic frameworks by studying the effect of various solvents on the insertion of Ni(2+) into MOF-5 and Co(2+) into MFU-4l. After plotting the extent of cation insertion versus different solvent parameters, trends emerge that offer insight into the exchange processes for both systems. This approach establishes a method for understanding critical aspects of cation exchange in different MOFs and other materials.

  12. Multilamellar structures of DNA complexes with cationic liposomes.

    PubMed

    Dan, N

    1997-10-01

    Studies of DNA complexes with cationic liposomes are prompted by the search for nonviral DNA carriers for gene therapy. Recent experiments have identified a stable multilamellar phase in which ordered smectic layers of DNA alternate with cationic bilayers. In this paper we identify the forces governing DNA adsorption on cationic lamellae, including a membrane-induced attraction between the adsorbed DNA. Calculating the DNA interhelical spacing as a function of system composition, the model successfully explains recent surprising observations.

  13. Effects of pergolide mesylate on transduction efficiency of PEP-1-catalase protein

    SciTech Connect

    Sohn, Eun Jeong; Kim, Dae Won; Kim, Young Nam; Kim, So Mi; Lim, Soon Sung; Kang, Tae-Cheon; Kwon, Hyeok Yil; Kim, Duk-Soo; Cho, Sung-Woo; Han, Kyu Hyung; Park, Jinseu; Eum, Won Sik; Hwang, Hyun Sook; Choi, Soo Young

    2011-03-18

    Research highlights: {yields} We studied effects of pergolide mesylate (PM) on in vitro and in vivo transduction of PEP-1-catalase. {yields} PEP-1-catatase inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation. {yields} PM enhanced the transduction of PEP-1-catalase into HaCaT cells and skin tissue. {yields} PM increased anti-inflammatory activity of PEP-1-catalase. {yields} PM stimulated therapeutic action of anti-oxidant enzyme catalase in oxidative-related diseases. -- Abstract: The low transduction efficiency of various proteins is an obstacle to their therapeutic application. However, protein transduction domains (PTDs) are well-known for a highly effective tool for exogenous protein delivery to cells. We examined the effects of pergolide mesylate (PM) on the transduction of PEP-1-catalase into HaCaT human keratinocytes and mice skin and on the anti-inflammatory activity of PEP-1-catatase against 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation using Western blot and histological analysis. PM enhanced the time- and dose-dependent transduction of PEP-1-catalase into HaCaT cells without affecting the cellular toxicity. In a mouse edema model, PEP-1-catalase inhibited the increased expressions of inflammatory mediators and cytokines such as cyclooxygenase-2, inducible nitric oxide synthase, interleukin-6 and -1{beta}, and tumor necrosis factor-{alpha} induced by TPA. On the other hand, PM alone failed to exert any significant anti-inflammatory effects. However, the anti-inflammatory effect of co-treatment with PEP-1-catalase and PM was more potent than that of PEP-1-catalase alone. Our results indicate that PM may enhance the delivery of PTDs fusion therapeutic proteins to target cells and tissues and has potential to increase their therapeutic effects of such drugs against various diseases.

  14. AAV-mediated photoreceptor transduction of the pig cone-enriched retina

    PubMed Central

    Mussolino, C; della Corte, M; Rossi, S; Viola, F; Di Vicino, U; Marrocco, E; Neglia, S; Doria, M; Testa, F; Giovannoni, R; Crasta, M; Giunti, M; Villani, E; Lavitrano, M; Bacci, M L; Ratiglia, R; Simonelli, F; Auricchio, A; Surace, E M

    2011-01-01

    Recent success in clinical trials supports the use of adeno-associated viral (AAV) vectors for gene therapy of retinal diseases caused by defects in the retinal pigment epithelium (RPE). In contrast, evidence of the efficacy of AAV-mediated gene transfer to retinal photoreceptors, the major site of inherited retinal diseases, is less robust. In addition, although AAV-mediated RPE transduction appears efficient, independently of the serotype used and species treated, AAV-mediated photoreceptor gene transfer has not been systematically investigated thus so far in large animal models, which also may allow identifying relevant species-specific differences in AAV-mediated retinal transduction. In the present study, we used the porcine retina, which has a high cone/rod ratio. This feature allows to properly evaluate both cone and rod photoreceptors transduction and compare the transduction characteristics of AAV2/5 and 2/8, the two most efficient AAV vector serotypes for photoreceptor targeting. Here we show that AAV2/5 and 2/8 transduces both RPE and photoreceptors. AAV2/8 infects and transduces photoreceptor more efficiently than AAV2/5, similarly to what we have observed in the murine retina. The use of the photoreceptor-specific rhodopsin promoter restricts transgene expression to porcine rods and cones, and results in photoreceptor transduction levels similar to those obtained with the ubiquitous promoters tested. Finally, immunological, toxicological and biodistribution studies support the safety of AAV subretinal administration to the large porcine retina. The data presented here on AAV-mediated transduction of the cone-enriched porcine retina may affect the development of gene-based therapies for rare and common severe photoreceptor diseases. PMID:21412286

  15. Generalized transduction for genetic linkage analysis and transfer of transposon insertions in different Staphylococcus epidermidis strains.

    PubMed

    Nedelmann, M; Sabottke, A; Laufs, R; Mack, D

    1998-01-01

    Staphylococcus epidermidis phage 48 was used to efficiently transduce plasmid pTV1ts and a chromosomal Tn917 insertion M27 from S. epidermidis 13-1 to biofilm-producing clinical S. epidermidis isolates 1457, 9142, and 8400. The Tn917 insertion leading to the biofilm-negative phenotype of transposon mutant M10 was sequentially transduced to biofilm-producing S. epidermidis 1457 using S. epidermidis phage 48 and then, using the resulting biofilm-negative transductant 1457-M10 as a donor, into several unrelated biofilm-producing clinical S. epidermidis isolates using S. epidermidis phage 71. All resultant transductants displayed a completely biofilm-negative phenotype. In addition, S. epidermidis phage 71 was adapted to S. epidermidis 1457 and 8400, which allowed generalized transduction of transposon insertions in these wild-type strains. As Tn917 predominantly transposed into endogenous plasmids of all three strains used, an efficient system for chromosomal transposon mutagenesis was established by curing of S. epidermidis 1457 of a single endogenous plasmid p1457 by sodium dodecylsulfate treatment. After transduction of the resulting derivative, S. epidermidis 1457c with pTV1ts, insertion of transposon Tn917 to different sites of the chromosome of S. epidermidis 1457c was observed. Biofilm-producing S. epidermidis 1457c x pTV1ts was used to isolate a biofilm-negative transposon mutant (1457c-M3) with a chromosomal insertion apparently different from two previously isolated isogenic biofilm-negative transposon mutants, M10 and M11 (Mack, D., M. Nedelmann, A. Krokotsch, A. Schwarzkopf, J. Heesemann, and R. Laufs: Infect Immun 62 [1994] 3244-3253). S. epidermidis phage 71 was used to prove genetic linkage between transposon insertion and altered phenotype by generalized transduction. In combination with phage transduction, 1457c x pTV1ts will be a useful tool facilitating the study of bacterial determinants of the pathogenicity of S. epidermidis.

  16. Infrared spectroscopic investigations of cationic ethanol, propanol, and butanol

    NASA Astrophysics Data System (ADS)

    Matsuda, Yoshiyuki; Harigaya, Hiroyuki; Xie, Min; Takahashi, Kaito; Fujii, Asuka

    2015-11-01

    Infrared spectroscopy of the alcohol cations of ethanol, propanol, and butanol was performed to investigate their structures and hyperconjugation mechanisms. In the ethanol cation, the Csbnd C bond hyperconjugates with the singly occupied molecular orbital (SOMO) at the oxygen atom, so that the Csbnd C bond weakens and the bond length elongates. Multiple hyperconjugations among SOMO, the Csbnd C bond, and the end Csbnd H bond occur in the propanol cation and enhance the acidity of the Csbnd H bond through the delocalization of its bonding σ electron. The butanol cation forms the oxonium-type structure through the proton transfer from the terminal CH bond.

  17. Hydroxide Degradation Pathways for Imidazolium Cations. A DFT Study

    SciTech Connect

    Long, H.; Pivovar, B.

    2014-05-15

    Imidazolium cations are promising candidates as covalently tetherable cations for application in anion exchange membranes. They have generated specific interest in alkaline membrane fuel cell applications where ammonium-based cations have been the most commonly applied but have been found to be susceptible to hydroxide attack. In the search for high stability cations, a detailed understanding of the degradation pathways and reaction barriers is required. In this work, we investigate imidazolium and benzimidazolium cations in the presence of hydroxide using density functional theory calculations for their potential in alkaline membrane fuel cells. Moreover, the dominant degradation pathway for these cations is predicted to be the nucleophilic addition–elimination pathway at the C-2 atom position on the imidazolium ring. Steric interferences, introduced by substitutions at the C-2, C-4, and C-5 atom positions, were investigated and found to have a significant, positive impact on calculated degradation energy barriers. Benzimidazolium cations, with their larger conjugated systems, are predicted to degrade much faster than their imidazolium counterparts. Our results provide important insight into designing stable cations for anion exchange membranes. Some of the molecules studied have significantly increased degradation energy barriers suggesting that they could possess significantly improved (several orders of magnitude) durability compared to traditional cations and potentially enable new applications.

  18. Trapping of neutral radicals by aromatic and heterocyclic cation radicals

    SciTech Connect

    Shine, H.J.; Soroka, M.

    1986-09-01

    A considerable amount of knowledge has been accrued during the last 15-20 years on the chemistry of polynuclear aromatic and heterocyclic cation radicals. For the most part, the reactions that have been studied have been of cation radicals with neutral and anionic nucleophiles which lead to addition or substitution products. Classic examples among these reactions are, for example, the reaction of water with the cation radical of 9,10-diphenylanthracene and perylene, and that of water with the thianthrene cation radical. Reactions such as these have been among foundation-establishing studies in the scope and mechanism of cation-radical reactions. Cation radicals can also undergo another type reaction with nucleophies, that is, electron transfer. This possibility leads to two far-reaching and connected questions: can addition and substitution reactions of aromatic cation radicals with nucleophiles be preceded by single electron transfer (SET).; and, can such cation radicals trap neutral radicals. These questions are also then related to another question having even greater impact on organic chemistry: can electrophilic aromatic substitution (ArH + E/sup +/ ..-->.. ArE + H/sup +/) be preceded by SET. The authors have been trying to answer the first two questions about SET and trapping of radicals by combining the two possibilities. That is, they have chosen the reaction of the thianthrene cation radical (represented by the symbol S/sup +./) with grignard reagents, for which two possible routes could be anticipated: either direct addition at sulfur or addition preceded by SET.

  19. Targeting prostate cancer based on signal transduction and cell cycle pathways

    PubMed Central

    Lee, John T.; Lehmann, Brian D.; Terrian, David M.; Chappell, William H.; Stivala, Franca; Libra, Massimo; Martelli, Alberto M.; Steelman, Linda S.

    2008-01-01

    Prostate cancer remains a leading cause of death in men despite increased capacity to diagnose at earlier stages. After prostate cancer has become hormone independent, which often occurs after hormonal ablation therapies, it is difficult to effectively treat. Prostate cancer may arise from mutations and dysregulation of various genes involved in regulation signal transduction (e.g., PTEN, Akt, etc.,) and the cell cycle (e.g., p53, p21Cip1, p27Kip1, Rb, etc.,). This review focuses on the aberrant interactions of signal transduction and cell cycle genes products and how they can contribute to prostate cancer and alter therapeutic effectiveness. PMID:18594202

  20. [Signal transduction and drug resistance in Mycobacterium tuberculosis--A review].

    PubMed

    Wang, Shanshan; Feng, Yi; Zhang, Zhe

    2015-08-01

    Mycobacterium tuberculosis infection kills two million people every year, and the chemotherapy has led to significant amount of drug resistance. Signal transduction systems are used by bacteria to survive or adapt to their living environment, but the relationship to drug resistance is not well understood. In this article, we introduced the two-component signal transduction systems of M. tuberculosis and analyzed their relationship with drug resistance. We identified five two-component system pairs involved in the formation of drug resistance. Therefore, these two-component systems are good targeting sites for small biochemical drugs to target so as to reverse the drug resistance and virulence.