WorldWideScience

Sample records for acid-labile cholesterol-vinyl ether-peg

  1. The acid-labile subunit of the ternary insulin-like growth factor complex in cirrhosis

    Møller, S; Juul, A; Becker, U;

    2000-01-01

    In the circulation, insulin-like growth factor-I (IGF-I) is bound in a trimeric complex of 150 kDa with IGF binding protein-3 (IGFBP-3) and the acid-labile subunit (ALS). Whereas circulating IGF-I and IGFBP-3 are reported to be low in patients with chronic liver failure, the level of ALS has...... not been described in relation to hepatic dysfunction. The aim of the present study was therefore to measure circulating and hepatic venous concentrations of ALS in relation to hepatic function and the IGF axis....

  2. Acid-Labile Amphiphilic PEO-b-PPO-b-PEO Copolymers: Degradable Poloxamer Analogs.

    Worm, Matthias; Kang, Biao; Dingels, Carsten; Wurm, Frederik R; Frey, Holger

    2016-05-01

    Poly ((ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)) triblock copolymers commonly known as poloxamers or Pluronics constitute an important class of nonionic, biocompatible surfactants. Here, a method is reported to incorporate two acid-labile acetal moieties in the backbone of poloxamers to generate acid-cleavable nonionic surfactants. Poly(propylene oxide) is functionalized by means of an acetate-protected vinyl ether to introduce acetal units. Three cleavable PEO-PPO-PEO triblock copolymers (Mn,total = 6600, 8000, 9150 g·mol(-1) ; Mn,PEO = 2200, 3600, 4750 g·mol(-1) ) have been synthesized using anionic ring-opening polymerization. The amphiphilic copolymers exhibit narrow molecular weight distributions (Ð = 1.06-1.08). Surface tension measurements reveal surface-active behavior in aqueous solution comparable to established noncleavable poloxamers. Complete hydrolysis of the labile junctions after acidic treatment is verified by size exclusion chromatography. The block copolymers have been employed as surfactants in a miniemulsion polymerization to generate polystyrene (PS) nanoparticles with mean diameters of ≈200 nm and narrow size distribution, as determined by dynamic light scattering and scanning electron microscopy. Acid-triggered precipitation facilitates removal of surfactant fragments from the nanoparticles, which simplifies purification and enables nanoparticle precipitation "on demand."

  3. The acid-labile subunit of human ternary insulin-like growth factor binding protein complex in serum

    Juul, A; Møller, S; Mosfeldt-Laursen, E;

    1998-01-01

    Circulating insulin-like growth factor-I (IGF-I) is predominantly bound in the trimeric complex comprised of IGF binding protein-3 (IGFBP-3) and acid-labile subunit (ALS). Circulating concentrations of IGF-I, IGFBP-3 and ALS are believed to reflect the GH secretory status, but the clinical use...... of ALS determination is not known. We therefore, determined the: 1) hepatosplanchnic release of ALS by liver vein catheterization (n=30); 2) 24-h diurnal variation of ALS (n=8); 3) normal age-related ranges of circulating ALS (n=1158); 4) diagnostic value of ALS in 108 patients with childhood-onset GH...... deficiency (GHD). We found: 1) no significant arteriovenous gradient over the liver ofALS, IGF-I, and IGFBP-3; 2) the diurnal variation of ALS was 12% (mean coefficient of variation percent); 3) ALS levels increased throughout childhood with maximal levels in puberty, with a subsequent decrease with age...

  4. The acid-labile subunit of the ternary insulin-like growth factor complex in cirrhosis: relation to liver dysfunction

    Møller, S; Juul, A; Becker, U;

    2000-01-01

    BACKGROUND/AIMS: In the circulation, insulin-like growth factor-I (IGF-I) is bound in a trimeric complex of 150 kDa with IGF binding protein-3 (IGFBP-3) and the acid-labile subunit (ALS). Whereas circulating IGF-I and IGFBP-3 are reported to be low in patients with chronic liver failure, the level...... of ALS has not been described in relation to hepatic dysfunction. The aim of the present study was therefore to measure circulating and hepatic venous concentrations of ALS in relation to hepatic function and the IGF axis. METHODS: Twenty-five patients with cirrhosis (Child class A/B/C:5/10/10) and 30...... controls with normal liver function were studied. During a haemodynamic investigation, blood samples were collected from the hepatic vein and femoral artery, and the plasma concentrations of ALS, IGF-I and IGFBP-3 were determined. RESULTS: Hepatic venous and arterial concentrations of ALS were...

  5. Molecular glass positive i-line photoresist materials containing 2,1,4-DNQ and acid labile group

    Wang, Liyuan; Yu, Jinxing; Xu, Na

    2010-04-01

    Recent years increasing attention has been given to molecular glass resist materials. In this paper, maleopimaric acid, cycloaddition reaction product of rosin with maleic anhydride, was reacted with hydroxylamine and then further esterified with 2-diazo-1-naphthoquinone-4-sulfonyl chloride to give N-hydroxy maleopimarimide sulfonate. The carboxylic acid group of the compound was then protected by the reaction of this compound with vinyl ethyl ether or dihydropyran. Thus obtained compounds were amorphous. When irradiated with i-line light, the 2,1,4-DNQ group undergo photolysis not only to give off nitrogen gas but also generate sulfonic acid which can result in the decomposition of the acid labile group. So, a novel chemically amplified positive i-line molecular glass photoresists can be formed by the compound and other acidolytic molecular glass compounds. The lithographic performance of the resist materials is evaluated.

  6. An acid-labile block copolymer of PDMAEMA and PEG as potential carrier for intelligent gene delivery systems.

    Lin, Song; Du, Fusheng; Wang, Yang; Ji, Shouping; Liang, Dehai; Yu, Lei; Li, Zichen

    2008-01-01

    Intelligent gene delivery systems based on physiologically triggered reversible shielding technology have evinced enormous interest due to their potential in vivo applications. In the present work, an acid-labile block copolymer consisting of poly(ethylene glycol) and poly(2-(dimethylamino)ethyl methacrylate) segments connected through a cyclic ortho ester linkage (PEG- a-PDMAEMA) was synthesized by atom transfer radical polymerization of DMAEMA using a PEG macroinitiator with an acid-cleavable end group. PEG- a-PDMAEMA condensed with plasmid DNA formed polyplex nanoparticles with an acid-triggered reversible PEG shield. The pH-dependent shielding/deshielding effect of PEG chains on the polyplex particles were evaluated by zeta potential and size measurements. At pH 7.4, polyplexes generated from PEG- a-PDMAEMA exhibited smaller particle size, lower surface charge, reduced interaction with erythrocytes, and less cytotoxicity compared to PDMAEMA-derived polyplexes. At pH 5.0, zeta potential of polyplexes formed from PEG- a-PDMAEMA increased, leveled up after 2 h of incubation and gradual aggregation occurred in the presence of bovine serum albumin (BSA). In contrast, the stably shielded polyplexes formed by DNA and an acid-stable block copolymer, PEG- b-PDMAEMA, did not change in size and zeta potential in 6 h. In vitro transfection efficiency of the acid-labile copolymer greatly increased after 6 h incubation at pH 5.0, approaching the same level of PDMAEMA, whereas there was only slight increase in efficiency for the stable copolymer, PEG- b-PDMAEMA.

  7. Low Molecular Weight PEI-Based Vectors via Acid-Labile Ortho Ester Linkage for Improved Gene Delivery.

    Zhang, Lei; Yu, Min; Wang, Jun; Tang, Rupei; Yan, Guoqing; Yao, Weijing; Wang, Xin

    2016-08-01

    A series of novel pH-sensitive gene delivery vectors (POEI 1, 2, and 3) are synthesized through Michael addition from low molecular weight PEI (LMW PEI) via acid-labile ortho ester linkage with terminal acrylates (OEAc) by various feed molar ratios. The obtained POEI 1 and POEI 2 can efficiently condense plasmid DNA into nanoparticles with size range of 200-300 nm and zeta-potentials of about +15 mV while protecting DNA from enzymatic digestion compared with POEI 3. Significantly, ortho ester groups of POEI main-chains can make an instantaneous degradation-response to acidic endosomal pH (≈5.0), resulting in accelerated disruption of polyplexes and intracellular DNA release. MTT assay reveals that all POEIs exhibit much lower cytotoxicity in different cells than branched PEI (25 KDa). As expected, POEI 1 and POEI 2 perform improved gene transfection in vitro, suggesting that such polycations might be promising gene vectors based on overcoming toxicity-efficiency contradiction.

  8. A simple and inexpensive enteric-coated capsule for delivery of acid-labile macromolecules to the small intestine.

    Miller, Darren S; Parsons, Anne Michelle; Bresland, John; Herde, Paul; Pham, Duc Minh; Tan, Angel; Hsu, Hung-yao; Prestidge, Clive A; Kuchel, Tim; Begg, Rezaul; Aziz, Syed Mahfuzul; Butler, Ross N

    2015-07-01

    Understanding the ecology of the gastrointestinal tract and the impact of the contents on the host mucosa is emerging as an important area for defining both wellness and susceptibility to disease. Targeted delivery of drugs to treat specific small intestinal disorders such as small bowel bacterial overgrowth and targeting molecules to interrogate or to deliver vaccines to the remote regions of the small intestine has proven difficult. There is an unmet need for methodologies to release probes/drugs to remote regions of the gastrointestinal tract in furthering our understanding of gut health and pathogenesis. In order to address this concern, we need to know how the regional delivery of a surrogate labeled test compound is handled and in turn, if delivered locally as a liquid or powder, the dynamics of its subsequent handling and metabolism. In the studies we report on in this paper, we chose (13)C sodium acetate ((13)C-acetate), which is a stable isotope probe that once absorbed in the small intestine can be readily measured non-invasively by collection and analysis of (13)CO2 in the breath. This would provide information of gastric emptying rates and an indication of the site of release and absorptive capacity. In a series of in vitro and in vivo pig experiments, we assessed the enteric-protective properties of a commercially available polymer EUDRAGIT(®) L100-55 on gelatin capsules and also on DRcaps(®). Test results demonstrated that DRcaps(®) coated with EUDRAGIT(®) L100-55 possessed enhanced enteric-protective properties, particularly in vivo. These studies add to the body of knowledge regarding gastric emptying in pigs and also begin the process of gathering specifications for the design of a simple and cost-effective enteric-coated capsule for delivery of acid-labile macromolecules to the small intestine.

  9. Development of pH-sensitive self-nanoemulsifying drug delivery systems for acid-labile lipophilic drugs.

    Zhao, Tianjing; Maniglio, Devid; Chen, Jie; Chen, Bin; Migliaresi, Claudio

    2016-03-01

    Oral administration is the most convenient way of all the drug delivery routes. Orally administered bioactive compounds must resist the harsh acidic fluids or enzyme digestion in stomach, to reach their absorbed destination in small intestine. This is the case for silibinin, a drug used to protect liver cells against toxins that has also been demonstrated in vitro to possess anti-cancer effects. However, as many other drugs, silibinin can degrade in the stomach due to the action of the gastric fluid. The use of pH-sensitive self-nanoemulsifying drug delivery systems (pH-SNEDDS) could overcome the drawback due to degradation of the drug in the stomach while enhancing its solubility and dissolution rate. In this paper we have investigated pH-sensitive self-nanoemulsifying formulations containing silibinin as model drug. Pseudo-ternary phase diagrams have been constructed in order to identify the self-emulsification regions under different pH. Solubility of silibinin in selected formulations has been assessed and stability of the pure drug and of the silibinin loaded pH-SNEDDS formulations in simulated gastric fluid had been compared. Droplet size of the optimized pH-SNEDDS has been correlated to pH, volume of dilution medium and silibinin loading amount. TEM (transmission electron microscopy) studies have shown that emulsion droplets had spherical shape and narrow size distribution. In vitro drug release studies of the optimal pH-SNEDDS indicated substantial increase of the drug release and release rate in comparison to pure silibinin and to the commercial silibinin tablet. The results indicated that pH-SNEDDS have potential to improve the biopharmaceutics properties of acid-labile lipophilic drugs.

  10. pH-responsive biodegradable micelles based on acid-labile polycarbonate hydrophobe: synthesis and triggered drug release.

    Chen, Wei; Meng, Fenghua; Li, Feng; Ji, Shun-Jun; Zhong, Zhiyuan

    2009-07-13

    pH-responsive biodegradable micelles were prepared from block copolymers comprising of a novel acid-labile polycarbonate hydrophobe and poly(ethylene glycol) (PEG). Two new cyclic aliphatic carbonate monomers, mono-2,4,6-trimethoxybenzylidene-pentaerythritol carbonate (TMBPEC, 2a) and mono-4-methoxybenzylidene-pentaerythritol carbonate (MBPEC, 2b) were designed and successfully synthesized via a two-step procedure. The ring-opening polymerization of 2a or 2b in the presence of methoxy PEG in dichloromethane at 50 °C using zinc bis[bis(trimethylsilyl)amide] as a catalyst yielded the corresponding block copolymers PEG-PTMBPEC (3a) or PEG-PMBPEC (3b) with low polydispersities (PDI 1.03-1.04). The copolymerization of D,L-lactide (DLLA) and 2a under otherwise the same conditions could also proceed smoothly to afford PEG-P(TMBPEC-co-DLLA) (3c) block copolymer. These block copolymers readily formed micelles in water with sizes of about 120 nm as determined by dynamic light scattering (DLS). The hydrolysis of the acetals of the polycarbonate was investigated using UV/vis spectroscopy. The results showed that the acetals of micelles 3a, while stable at pH 7.4 are prone to rapid hydrolysis at mildly acidic pH of 4.0 and 5.0, with a half-life of 1 and 6.5 h, respectively. The acetal hydrolysis resulted in significant swelling of micelles, as a result of change of hydrophobic polycarbonate to hydrophilic polycarbonate. In comparison, the acetals of PMBPEC of micelles 3b displayed obviously slower hydrolysis at the same pH. Both paclitaxel and doxorubicin could be efficiently encapsulated into micelles 3a achieving high drug loading content (13.0 and 11.7 wt %, respectively). The in vitro release studies showed clearly a pH dependent release behavior, that is, significantly faster drug release at mildly acidic pH of 4.0 and 5.0 compared to physiological pH. These pH-responsive biodegradable micelles are promising as smart nanovehicles for targeted delivery of anticancer drugs.

  11. Detection of a variable intracellular acid-labile carbon pool in Thalassiosira weissflogii (Heterokontophyta) and Emiliania huxleyi (Haptophyta) in response to changes in the seawater carbon system.

    Isensee, Kirsten; Erez, Jonathan; Stoll, Heather M

    2014-02-01

    Accumulation of an intracellular pool of carbon (C(i) pool) is one strategy by which marine algae overcome the low abundance of dissolved CO2 (CO2 (aq) ) in modern seawater. To identify the environmental conditions under which algae accumulate an acid-labile C(i) pool, we applied a (14) C pulse-chase method, used originally in dinoflagellates, to two new classes of algae, coccolithophorids and diatoms. This method measures the carbon accumulation inside the cells without altering the medium carbon chemistry or culture cell density. We found that the diatom Thalassiosira weissflogii [(Grunow) G. Fryxell & Hasle] and a calcifying strain of the coccolithophorid Emiliania huxleyi [(Lohmann) W. W. Hay & H. P. Mohler] develop significant acid-labile C(i) pools. C(i) pools are measureable in cells cultured in media with 2-30 µmol l(-1) CO2 (aq), corresponding to a medium pH of 8.6-7.9. The absolute C(i) pool was greater for the larger celled diatoms. For both algal classes, the C(i) pool became a negligible contributor to photosynthesis once CO2 (aq) exceeded 30 µmol l(-1) . Combining the (14) C pulse-chase method and (14) C disequilibrium method enabled us to assess whether E. huxleyi and T. weissflogii exhibited thresholds for foregoing accumulation of DIC or reduced the reliance on bicarbonate uptake with increasing CO2 (aq) . We showed that the C(i) pool decreases with higher CO2 :HCO3 (-) uptake rates.

  12. Mass spectrometry method to identify aging pathways of Sp- and Rp-tabun adducts on human butyrylcholinesterase based on the acid labile P-N bond.

    Jiang, Wei; Cashman, John R; Nachon, Florian; Masson, Patrick; Schopfer, Lawrence M; Lockridge, Oksana

    2013-04-01

    The phosphoramidate nerve agent tabun inhibits butyrylcholinesterase (BChE) and acetylcholinesterase by making a covalent bond on the active site serine. The adduct loses an alkyl group in a process called aging. The mechanism of aging of the tabun adduct is controversial. Some studies claim that aging proceeds through deamination, whereas crystal structure studies show aging by O-dealkylation. Our goal was to develop a method that clearly distinguishes between deamination and O-dealkylation. We began by studying the tetraisopropyl pyrophosphoramide adduct of BChE because this adduct has two P-N bonds. Mass spectra showed that the P-N bonds were stable during trypsin digestion at pH 8 but were cleaved during pepsin digestion at pH 2. The P-N bond in tabun was also acid labile, whereas the P-O bond was stable. A scheme to distinguish aging by deamination from aging by O-dealkylation was based on the acid labile P-N bond. BChE was inhibited with Sp- and Rp-tabun thiocholine nerve agent model compounds to make adducts identical to those of tabun with known stereochemistry. After aging and digestion with pepsin at pH 2, peptide FGES198AGAAS from Sp-tabun thiocholine had a mass of 902.2 m/z in negative mode, indicating that it had aged by deamination, whereas peptide FGES198AGAAS from Rp-tabun thiocholine had a mass of 874.2 m/z in negative mode, indicating that it had aged by O-dealkylation. BChE inhibited by authentic, racemic tabun yielded both 902.2 and 874.2 m/z peptides, indicating that both stereoisomers reacted with BChE and aged either by deamination or dealkylation.

  13. Application of nanoparticles for oral delivery of acid-labile lansoprazole in the treatment of gastric ulcer: in vitro and in vivo evaluations.

    Alai, Milind; Lin, Wen Jen

    2015-01-01

    The aim of this study was to develop nanoparticles for oral delivery of an acid-labile drug, lansoprazole (LPZ), for gastric ulcer therapy. LPZ-loaded positively charged Eudragit(®) RS100 nanoparticles (ERSNPs-LPZ) and negatively charged poly(lactic-co-glycolic acid) nanoparticles (PLGANPs-LPZ) were prepared. The effect of charge on nanoparticle deposition in ulcerated and non-ulcerated regions of the stomach was investigated. The cellular uptake of nanoparticles in the intestine was evaluated in a Caco-2 cell model. The pharmacokinetic performance and ulcer healing response of LPZ-loaded nanoparticles following oral administration were evaluated in Wistar rats with induced ulcers. The prepared drug-loaded ERSNPs-LPZ and PLGANPs-LPZ possessed opposite surface charge (+38.5±0.3 mV versus -27.3±0.3 mV, respectively) and the particle size was around 200 nm with a narrow size distribution. The negatively charged PLGANPs adhered more readily to the ulcerated region (7.22%±1.21% per cm(2)), whereas the positively charged ERSNPs preferentially distributed in the non-ulcerated region (8.29%±0.35% per cm(2)). Both ERSNPs and PLGANPs were prominent uptake in Caco-2 cells, too. The nanoparticles sustained and prolonged LPZ concentrations up to 24 hours, and the half-life and mean residence time of LPZ were prolonged by 3.5-fold and 4.5-fold, respectively, as compared with LPZ solution. Oral administration of LPZ-loaded nanoparticles healed 92.6%-95.7% of gastric ulcers in Wistar rats within 7 days.

  14. Application of nanoparticles for oral delivery of acid-labile lansoprazole in the treatment of gastric ulcer: in vitro and in vivo evaluations

    Alai M

    2015-06-01

    Full Text Available Milind Alai,1 Wen Jen Lin1,2 1Graduate Institute of Pharmaceutical Sciences, School of Pharmacy, 2Drug Research Center, College of Medicine, National Taiwan University, Taipei, Taiwan Abstract: The aim of this study was to develop nanoparticles for oral delivery of an acid-labile drug, lansoprazole (LPZ, for gastric ulcer therapy. LPZ-loaded positively charged Eudragit® RS100 nanoparticles (ERSNPs-LPZ and negatively charged poly(lactic-co-glycolic acid nanoparticles (PLGANPs-LPZ were prepared. The effect of charge on nanoparticle deposition in ulcerated and non-ulcerated regions of the stomach was investigated. The cellular uptake of nanoparticles in the intestine was evaluated in a Caco-2 cell model. The pharmacokinetic performance and ulcer healing response of LPZ-loaded nanoparticles following oral administration were evaluated in Wistar rats with induced ulcers. The prepared drug-loaded ERSNPs-LPZ and PLGANPs-LPZ possessed opposite surface charge (+38.5±0.3 mV versus -27.3±0.3 mV, respectively and the particle size was around 200 nm with a narrow size distribution. The negatively charged PLGANPs adhered more readily to the ulcerated region (7.22%±1.21% per cm2, whereas the positively charged ERSNPs preferentially distributed in the non-ulcerated region (8.29%±0.35% per cm2. Both ERSNPs and PLGANPs were prominent uptake in Caco-2 cells, too. The nanoparticles sustained and prolonged LPZ concentrations up to 24 hours, and the half-life and mean residence time of LPZ were prolonged by 3.5-fold and 4.5-fold, respectively, as compared with LPZ solution. Oral administration of LPZ-loaded nanoparticles healed 92.6%–95.7% of gastric ulcers in Wistar rats within 7 days. Keywords: nanoparticles, lansoprazole, Eudragit® RS100, PLGA

  15. Normal growth spurt and final height despite low levels of all forms of circulating insulin-like growth factor-I in a patient with acid-labile subunit deficiency

    Domené, Horacio M; Martínez, Alicia S; Frystyk, Jan;

    2007-01-01

    of circulating versus locally produced IGF-I in skeletal growth in this patient, we now describe in detail growth changes and their relationship with several components of the circulating IGF system. DESIGN AND METHODS: We followed growth and development up to the final height in a patient with complete ALS...... deficiency and determined both spontaneous and growth hormone (GH)-stimulated changes in the IGF system, including measurements of total, free and bioactive IGF-I, total IGF-II and insulin-like growth factor binding protein (IGFBP)-1, IGFBP-2 and IGFBP-3. RESULTS: The patient had a delayed growth......BACKGROUND: In a recently described patient with acid-labile subunit (ALS) deficiency, the inability to form ternary complexes resulted in a marked reduction in circulating total insulin-like growth factor (IGF)-I, whereas skeletal growth was only marginally affected. To further study the role...

  16. Long-term effects of insulin-like growth factor (IGF)-I on serum IGF-I, IGF-binding protein-3 and acid labile subunit in Laron syndrome patients with normal growth hormone binding protein.

    Kanety, H; Silbergeld, A; Klinger, B; Karasik, A; Baxter, R C; Laron, Z

    1997-12-01

    A minority of patients with Laron syndrome have normal serum GH binding protein (GHBP), indicating that the defect is elsewhere than in the extracellular domain of the GH receptor. We have evaluated the effect of long-term IGF-I treatment on serum IGF-binding protein (IGFBP)-3 and the acid-labile subunit (ALS) in three sibling with Laron syndrome caused by a GH post-receptor defect and with normal GHBP. The children (a boy aged 3 years, a girl aged 4 years and a boy aged 10 years) were treated by daily s.c. injection of IGF-I in a dose of 150 micrograms/kg. IGFBP-3 was measured by RIA and Western ligand blotting, ALS by RIA. Based values of IGFBP-3 and ALS were low. During IGF-I treatment, the IGFBP-3 concentrations in the girl gradually increased, whereas in the boys there was a 60% decrease during the first week, followed by gradual increase towards baseline. The ALS concentrations followed a similar pattern. We conclude that IGF-I treatment induces and initial suppression and then an increase in the IGFBP-3 and ALS concentrations, confirming data from animal experiments that IGFBP-3 synthesis is not solely under GH control. The differences in responsiveness between the female and male siblings may reflect genetic differences, or lower circulating concentrations of IGF-I in the boys compared with the girl.

  17. Acid-labile sulfides in shallow marine bottom sediments: A review of the impact on ecosystems in the Azov Sea, the NE Black Sea shelf and NW Adriatic lagoons

    Sorokin, Yu. I.; Zakuskina, O. Yu

    2012-02-01

    Acid-labile sulfides (LS) increase in bottom sediments at sites in the Azov Sea, at the NE Black Sea shelf and in the coastal lagoons of NW Adriatic Sea experiencing direct impacts of anthropogenic pollution. Fresh anthropogenic organic matter stimulates the bacterial sulfate reduction and here the rate of the LS production overcomes their loss during the oxidation and pyritization. This results in the expansion of reduced sediment layer up to the bottom surface. The LS concentration in the reduced sediments varies between 300 and 2000 mg S l -1 of wet silt depending on the size of pollution loading and on the rate of sedimentation. In the oxidized sediments away from the direct pollution impact, the LS concentration did not exceed 100-150 mg S l -1. Being a strong cytochrome toxin, the LS adversely affect the coastal ecosystems. The concentrations over 600 mg S l -1 result in quasi total benthic mortality whereas >300-400 mg S l -1 depletes the benthic faunal abundance and taxonomic diversity. Accumulation of the LS in sediments also induces nocturnal hypoxia and stimulates domination of toxic cyanobacteria in the pelagic phytocenoses.

  18. A simple and inexpensive enteric-coated capsule for delivery of acid-labile macromolecules to the small intestine%题目:一种用于递送酸度敏感大分子到小肠的简易且廉价的肠溶胶囊

    Darren S MILLER; Rezaul BEGG; Syed Mahfuzul AZIZ; Ross N BUTLER; Anne Michelle PARSONS; John BRESLAND; Paul HERDE; Duc Minh PHAM; Angel TAN; Hung-yao HSU; Clive A PRESTIDGE; Tim KUCHEL

    2015-01-01

    Understanding the ecology of the gastrointestinal tract and the impact of the contents on the host mucosa is emerging as an important area for defining both welness and susceptibility to disease. Targeted delivery of drugs to treat specific smal intestinal disorders such as smal bowel bacterial overgrowth and targeting molecules to interrogate or to deliver vaccines to the remote regions of the smal intestine has proven difficult. There is an unmet need for methodologies to release probes/drugs to remote regions of the gastrointestinal tract in furthering our understanding of gut health and pathogenesis. In order to address this concern, we need to know how the regional delivery of a sur-rogate labeled test compound is handled and in turn, if delivered localy as a liquid or powder, the dynamics of its subsequent handling and metabolism. In the studies we report on in this paper, we chose13C sodium acetate (13C-acetate), which is a stable isotope probe that once absorbed in the smal intestine can be readily measured non-invasively by colection and analysis of13CO2 in the breath. This would provide information of gastric emptying rates and an indication of the site of release and absorptive capacity. In a series ofin vitro andin vivo pig experiments, we assessed the enteric-protective properties of a commercialy available polymer EUDRAGIT® L100-55 on gelatin capsules and also on DRcaps®. Test results demonstrated that DRcaps® coated with EUDRAGIT® L100-55 possessed enhanced enteric-protective properties, particularlyin vivo. These studies add to the body of knowledge regarding gastric emptying in pigs and also begin the process of gathering specifications for the design of a simple and cost-effective enteric-coated capsule for delivery of acid-labile macromolecules to the smal intestine.%目的:通过开展胃肠道远端释放药物的研究,以增加对肠道健康和发病机制的理解。创新点:本研究选择了13C醋酸钠作为同位素探针,

  19. SUBNANOMOLAR DETECTION OF ACID-LABILE SULFIDES BY THE CLASSICAL METHYLENE BLUE METHOD COUPLED TO HPLC. (R825395)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  20. The acid-labile subunit of human ternary insulin-like growth factor binding protein complex in serum

    Juul, A; Møller, S; Mosfeldt-Laursen, E;

    1998-01-01

    of ALS determination is not known. We therefore, determined the: 1) hepatosplanchnic release of ALS by liver vein catheterization (n=30); 2) 24-h diurnal variation of ALS (n=8); 3) normal age-related ranges of circulating ALS (n=1158); 4) diagnostic value of ALS in 108 patients with childhood-onset GH...

  1. Total and free insulin-like growth factor I, insulin-like growth factor binding protein 3 and acid-labile subunit reflect clinical activity in acromegaly

    Sneppen, S B; Lange, Merete Wolder; Pedersen, L M;

    2001-01-01

    The aim was to evaluate, markers of disease activity in acromegaly in relation to perceived disease activity. Thirty-seven consecutively treated, acromegalic patients, classified by clinical symptoms as inactive (n=16), slightly active (n=10) and active (n=11), entered the study. When evaluating......-like growth factor binding protein-3 (IGFBP-3) with PV(pos) of 0.69 and 0.71 and PV(neg) of 0.91 and 0.92 respectively. We conclude that free IGF-I is more closely related than total IGF-I to perceived disease activity and is as such useful when evaluating previously treated acromegaly for disease activity...

  2. Exploring the potential of self-assembled mixed micelles in enhancing the stability and oral bioavailability of an acid-labile drug.

    Zhang, Xingwang; Wang, Huan; Zhang, Tianpeng; Zhou, Xiaotong; Wu, Baojian

    2014-10-01

    Oral delivery of many drugs is plagued with limited solubility and/or poor stability. This paper aimed to explore the performance of polymeric mixed micelles on solubilization, stabilization and bioavailability enhancement with stiripentol as model drug. Stiripentol-loaded mixed micelles were prepared by solvent-diffusion method: rapid dispersion of an ethanol solution containing stiripentol, monomethoxy poly(ethylene glycol)-b-poly(ε-caprolactone) and sodium oleate into water. Stiripentol micelles were characterized by the particle size, entrapment efficiency, in vitro drug release, TEM, DSC and FTIR. The pharmacokinetic profile of stiripentol was determined in rats after oral administration of stiripentol micelles. The obtained stiripentol micelles were 44.2 nm in size with an entrapment efficiency over 90%. It was shown that micelles substantially improved the solubility and gastric stability of stiripentol. The oral absorption of stiripentol was also enhanced to a great extent with a relative bioavailability of 157% and 444% to the commercial formulation (Diacomit®) and in-house suspensions. Mixed micelles assembled by di-block copolymer/sodium oleate exhibited a good potential in the improvement of drug stability and bioavailability. It should be a promising carrier for oral delivery of therapeuticals with solubility and stability issues.

  3. The ortho backbone amide linker (o-BAL) is an easily prepared and highly acid-labile handle for solid-phase synthesis

    Boas, Ulrik; Brask, Jesper; Christensen, J.B.;

    2002-01-01

    The tris(alkoxy)benzyl backbone amide linker (BAL) has found widespread application in solid-phase synthesis. The key intermediate for preparation of para BAL (p-BAL) is 2,6-dimethoxy-4-hydroxybenzaldehyde; several reports on its synthesis have appeared. However, the ortho analogue of the handle (o...

  4. Improved tryptic digestion assisted with an acid-labile anionic surfactant for the separation and characterization of glycopeptide glycoforms of a proteolytic-resistant glycoprotein by capillary electrophoresis time-of-flight mass spectrometry.

    Barroso, Albert; Giménez, Estela; Benavente, Fernando; Barbosa, José; Sanz-Nebot, Victoria

    2016-04-01

    Certain glycoproteins are rather difficult to digest due to compacted tertiary or quaternary structures. In a previous study, a capillary LC coupled to TOF-MS (μLC-TOF-MS) method was developed for the detection and characterization of the glycopeptide glycoforms of human transferrin (Tf), a proteolytic resistant glycoprotein, in serum samples. After immunoaffinity purification, Tf was digested with trypsin in the presence of RapiGest(®) and μLC-TOF-MS analyses permitted to detect the N413 and N611 glycopeptide glycoforms. Conversely, the use of this surfactant, albeit mandatory to quantitatively digest the isolated Tf, proved detrimental to CE-TOF-MS analysis due to its interaction with the inner surface of the silica capillary walls. As CE is usually regarded as an interesting alternative to other separation techniques (low consumption of reagents, excellent separation efficiency, and reduced analysis times), in this work, the undesirable interferences of the surfactant have been removed to allow the correct separation and detection of Tf glycoforms by CE-TOF-MS. Moreover, the digestion protocol described by the RapiGest(®) manufacturer has been modified to minimize desialylation of Tf glycopeptide glycoforms. The new developed CE-TOF-MS methodology has been then compared with the former μLC-TOF-MS by means of sensitivity and separation efficiency of Tf glycopeptide glycoforms in the standard glycoprotein. Additionally, Tf glycopeptide glycoforms from serum of healthy volunteers and patients with congenital disorders of glycosylation have also been analyzed following the developed methodology.

  5. Effects of short-term caloric restriction on circulating free IGF-I, acid-labile subunit, IGF-binding proteins (IGFBPs)-1-4, and IGFBPs-1-3 protease activity in obese subjects

    Rasmussen, Michael Højby; Juul, Anders; Kjems, Lise Lund

    2006-01-01

    Decreased levels of GH and total IGF-I have been reported in obesity. It has been hypothesized that increased free (biologically active) IGF-I levels generated from IGF-binding protein (IGFBP) protease activity could be the mechanism for the low GH release in dieting obese subjects. However, no p...... a short-term very low-calorie diet (VLCD)....

  6. Optimization of enzymatic synthesis of asialoglycoprotein receptor ligand cholesterol-vinyl sebacate-lactitol%去唾液酸糖蛋白受体配体胆固醇-半乳糖苷的酶促合成优化研究

    陈静; 程怡; 郑品劲; 聂华; 陈宇潮; 仝一丹; 罗利华; 李朝

    2015-01-01

    目的 在有机相中利用酶促反应合成能被去唾液酸糖蛋白受体(ASGPR)特异性识别的配体胆固醇-半乳糖苷分子,对其合成工艺进行优化.方法 采用质谱和核磁碳谱鉴别产物结构;单因素和正交设计法优化酶促合成条件.结果 酶促最佳条件为底物胆固醇癸二酸乙烯酯(CH-VS)与乳糖醇(LA)物质的量之比4∶1,脂肪酶Novozym 435 25 mg,反应32 h,产率高达92%.结论 该方法高效、反应条件可行、产物专一.

  7. Biodegradable containers from green waste materials

    Sartore, Luciana; Schettini, Evelia; Pandini, Stefano; Bignotti, Fabio; Vox, Giuliano; D'Amore, Alberto

    2016-05-01

    Novel biodegradable polymeric materials based on protein hydrolysate (PH), derived from waste products of the leather industry, and poly(ethylene glycol) diglycidyl ether (PEG) or epoxidized soybean oil (ESO) were obtained and their physico-chemical properties and mechanical behaviour were evaluated. Different processing conditions and the introduction of fillers of natural origin, as saw dust and wood flour, were used to tailor the mechanical properties and the environmental durability of the product. The biodegradable products, which are almost completely manufactured from renewable-based raw materials, look promising for several applications, particularly in agriculture for the additional fertilizing action of PH or in packaging.

  8. Traceless Azido Linker for the Solid-Phase Synthesis of NH-1,2,3-Triazoles via Cu-Catalyzed Azide-Alkyne Cycloaddition Reactions

    Cohrt, Anders Emil; Jensen, Jakob Feldthusen; Nielsen, Thomas Eiland

    2010-01-01

    A broadly useful acid-labile traceless azido linker for the solid-phase synthesis of NH-1,2,3-triazoles is presented. A variety of alkynes were efficiently immobilized on a range of polymeric supports by Cu(I)-mediated azide-alkyne cycloadditions. Supported triazoles showed excellent compatibility...

  9. A spiking neuron circuit based on a carbon nanotube transistor.

    Chen, C-L; Kim, K; Truong, Q; Shen, A; Li, Z; Chen, Y

    2012-07-11

    A spiking neuron circuit based on a carbon nanotube (CNT) transistor is presented in this paper. The spiking neuron circuit has a crossbar architecture in which the transistor gates are connected to its row electrodes and the transistor sources are connected to its column electrodes. An electrochemical cell is incorporated in the gate of the transistor by sandwiching a hydrogen-doped poly(ethylene glycol)methyl ether (PEG) electrolyte between the CNT channel and the top gate electrode. An input spike applied to the gate triggers a dynamic drift of the hydrogen ions in the PEG electrolyte, resulting in a post-synaptic current (PSC) through the CNT channel. Spikes input into the rows trigger PSCs through multiple CNT transistors, and PSCs cumulate in the columns and integrate into a 'soma' circuit to trigger output spikes based on an integrate-and-fire mechanism. The spiking neuron circuit can potentially emulate biological neuron networks and their intelligent functions.

  10. Glucolipids of Zea mays and Pisum sativum

    Morohashi, Y.; Bandurski, R.S.

    1976-06-01

    The glucolipids formed upon feeding (U--/sup 14/C)glucose to embryos of Zea mays were partially characterized with respect to: (a) metabolic turnover, (b) acid lability, (c) phosphorus content, (d) chromatographic properties, and (e) hydrolysis products. The chloroform--methanol-soluble-assimilated radioactivity was examined specifically for occurrence of a glycosylated prenol phosphate. With the extraction conditions used, no evidence was found for formation of a glucosylated prenol phosphate. Several, as yet unidentified, acid-labile glucolipids undergoing metabolic turnover were observed. Four diglycerides were characterized as hydrolysis products of a fraction that contained /sup 14/C-glucose and phosphorus, and was subject to metabolic turnover. Examination of the 1-butanol-soluble glucolipids from pea (Pisum sativum) seedlings also demonstrated anionic glucolipids, evidencing metabolic turnover but none with the properties of glucosylated prenol phosphate.

  11. B(C6F5)3 catalyzed one-pot three-component Biginelli reaction: An efficient and environmentally benign protocol for the synthesis of 3,4-dihydropyrimidin-2(1)-ones/thiones

    Santosh Kumar Prajapti; Keshav Kumar Gupta; Bathini Nagendra Babu

    2015-06-01

    Tris(pentafluorophenyl)borane catalyzed, one-pot, simple, efficient and environmentally benign protocol for the synthesis of dihydropyrimidinones/thiones via Biginelli reaction has been described. The main highlights of the present protocol is low catalyst loading, low toxicity, compatibility with acid-labile-protecting groups, short reaction time, consistently excellent yields and simple reaction/workup procedure. Moreover, the applicability of the present methodology for large-scale synthesis of monastrol highlights its potential for bulk synthesis.

  12. Light Scattering by Marine Particles: Modeling with Non-Spherical Shapes

    2011-04-15

    diameter of the disks is ~ 3 urn, and the thickness of each plate is ~ 50 -100 nm, and the material is calcite . The structures resembling spokes of a...per mole of calcite , rather than a per coccolith basis, it agreed reasonably well with that determined for acid-labile backscattering at 632 nm...disk or two roughly parallel disks) and a known composition ( Calcite , refractive index relative to water ~ 1.20). (See Ref. 5 for scanning electron

  13. Nanoemulsions as novel oral carriers of stiripentol: insights into the protective effect and absorption enhancement

    Lu R; Liu S.; Wang Q.; Li X.

    2015-01-01

    Rong Lu,1 Shan Liu,1 Qilin Wang,1 Xia Li1,2 1School of Ocean, Shandong University, Weihai, 2School of Pharmaceutical Sciences, Shandong University, Jinan, People’s Republic of China Abstract: Oral administration remains a significant challenge in regards to drugs with serious solubility and stability issues. This article aimed to investigate the suitability of nanoemulsions as oral carriers of stiripentol (STP), an acid-labile drug, for enhancement of stability and bioavail...

  14. Simulating the co-encapsulation of drugs in a "smart" core-shell-shell polymer nanoparticle.

    Buxton, Gavin A

    2014-03-01

    A coarse-grained lattice Monte Carlo method is used to simulate co-encapsulation and delivery of both a hydrophilic and hydrophobic drug from polymer nanoparticles. In particular, core-shell-shell polymer nanoparticles with acid-labile bonds are simulated, and the preferential release of the encapsulated drugs near more acidic tumors is captured. While these simple models lack the molecular details of a real system, they can reveal interesting insights concerning the effects of entropy and enthalpy in these systems.

  15. Structure and genetics of biosynthesis of the glycosyl phosphate-containing O-polysaccharide of Escherichia coli O160.

    Perepelov, Andrei V; Guo, Xi; Senchenkova, Sof'ya N; Shashkov, Alexander S; Knirel, Yuriy A

    2015-11-19

    On mild acid degradation of the lipopolysaccharide of Escherichia coli O160, the O-polysaccharide was cleaved by acid-labile glycosyl phosphate linkages in the main chain. The resultant oligosaccharide and the alkali-treated lipopolysaccharide were studied by sugar analysis along with (1)H and (13)C NMR spectroscopies, and the following structure of the branched pentasaccharide repeating unit of the O-polysaccharide was established: The O-antigen gene cluster of E. coli O160 was found to be consistent with the O-polysaccharide structure established.

  16. Requirement for development of dental adhesives

    2016-01-01

    Alan Boyde and his colleagues first described smear layers-covered dental hard tissues. Later, David Eick and his group examined smear layer-covered dentin and showed how acid-labile are smear layers. A superior bond strength has come to be provided for the resin-dentin interface in the current dental adhesive systems as a result that the acid-etching treatment for the enamel/dentin was examined to remove smear layers. Moreover, latest adhesive systems which gave top priority to convenience i...

  17. Automated radiosyntheses of [6-0-methyl-[sup 11]C]diprenorphine and [6-0-methyl-[sup 11]C]buprenorphine from 3-0-trityl protected precursors

    Luthra, S.K.; Brady, F.; Turton, D.R.; Brown, D.J.; Dowsett, K.; Waters, S.L.; Jones, A.K.P. (Hammersmith Hospital, London (United Kingdom). M.R.C. Cyclotron Unit); Matthews, R.W.; Crowder, J.C. (North London Univ., London (United Kingdom). School of Applied Chemistry)

    1994-08-01

    The antagonist [6-0-methyl-[sup 11]C]diprenorphine and the mixed agonist/antagonist [6-0-methyl-[sup 11]C]buprenorphine, radioligands for studying the opioid receptor system in vivo with positron emission tomography, were preapred by 0-methylation of (3-0-trityl, 6-desmethyl)diprenorphine and [3-0-trityl,6-desmethyl]buprenorphine, respectively, with [[sup 11]C]iodomethane. The use of the base-stable, acid labile trityl protecting group minimizes the formation of byproducts and allows reproducible radiosyntheses. (author).

  18. 2-Phenyl-tetrahydropyrimidine-4(1H-ones – cyclic benzaldehyde aminals as precursors for functionalised β2-amino acids

    Markus Nahrwold

    2009-09-01

    Full Text Available Novel procedures have been developed to condense benzaldehyde effectively with β-amino acid amides to cyclic benzyl aminals. Double carbamate protection of the heterocycle resulted in fully protected chiral β-alanine derivatives. These serve as universal precursors for the asymmetric synthesis of functionalised β2-amino acids containing acid-labile protected side chains. Diastereoselective alkylation of the tetrahydropyrimidinone is followed by a chemoselective two step degradation of the heterocycle to release the free β2-amino acid. In the course of this study, an L-asparagine derivative was condensed with benzaldehyde and subsequently converted to orthogonally protected (R-β2-homoaspartate.

  19. Tuneable drug-loading capability of chitosan hydrogels with varied network architectures

    Tronci, Giuseppe; Russell, Stephen J; Wood, David J; Akashi, Mitsuru

    2013-01-01

    Advanced bioactive systems with defined macroscopic properties and spatio-temporal sequestration of extracellular biomacromolecules are highly desirable for next generation therapeutics. Here, chitosan hydrogels were prepared with neutral or negatively-charged crosslinkers in order to promote selective electrostatic complexation with charged drugs. Chitosan (CT) was functionalised with varied dicarboxylic acids, such as tartaric acid (TA), poly(ethylene glycol) bis(carboxymethyl) ether (PEG), 1.4-Phenylenediacetic acid (4Ph) and 5-Sulfoisophthalic acid monosodium salt (PhS), whereby PhS was hypothesised to act as a simple mimetic of heparin. ATR FT-IR showed the presence of C=O amide I, N-H amide II and C=O ester bands, providing evidence of covalent network formation. The crosslinker content was reversely quantified by 1H-NMR on partially-degraded network oligomers, so that 18 mol% PhS was exemplarily determined. Swellability, compressability, material morphology, and drug-loading capability were successfull...

  20. Miniaturizable Ion-Selective Arrays Based on Highly Stable Polymer Membranes for Biomedical Applications

    Mònica Mir

    2014-07-01

    Full Text Available Poly(vinylchloride (PVC is the most common polymer matrix used in the fabrication of ion-selective electrodes (ISEs. However, the surfaces of PVC-based sensors have been reported to show membrane instability. In an attempt to overcome this limitation, here we developed two alternative methods for the preparation of highly stable and robust ion-selective sensors. These platforms are based on the selective electropolymerization of poly(3,4-ethylenedioxythiophene (PEDOT, where the sulfur atoms contained in the polymer covalently interact with the gold electrode, also permitting controlled selective attachment on a miniaturized electrode in an array format. This platform sensor was improved with the crosslinking of the membrane compounds with poly(ethyleneglycol diglycidyl ether (PEG, thus also increasing the biocompatibility of the sensor. The resulting ISE membranes showed faster signal stabilization of the sensor response compared with that of the PVC matrix and also better reproducibility and stability, thus making these platforms highly suitable candidates for the manufacture of robust implantable sensors.

  1. Hemocompatibility and cytocompatibility of the hirudin-modified silk fibroin.

    Sun, Dan; Hao, Yunxia; Yang, Gaoqiang; Wang, Jiannan

    2015-04-01

    Hirudin (Hir), a thrombin direct inhibitor, was used to modify a polyethylene glycol diglycidyl ether (PEG-DE) crosslinked regenerated silk fibroin (SF) material to improve hemocompatibility. Hemolysis characteristics, platelet adhesion, platelet activity, and plasma recalcification time were investigated using absorption spectrometry, scanning electron microscopy, MTT analysis, and the time counting method. Hirudin could be grafted evenly to the silk fibroin, and the modified material was resistant to hemolysis at ratios of less than 0.5%. Scanning electron microscopy and MTT results showed that platelet adhesion and aggregation activity decreased after modificaton with trace amounts of hirudin, compared with PEG-DE crosslinked and ethanol-treated silk fibroin film. Plasma recalcification of PEG-DE crosslinked silk fibroin film was slower than with ethanol-treated material, and this increased slightly after hirudin modification. Furthermore, L929, HAVSMC, and HUVEC cells adhered to the modified material, grew well, and possessed high proliferation activity on SF/Hir blend films. This study suggests that hirudin could improve the anticoagulation properties of regenerated silk fibroin materials.

  2. Protein-resistant polymer coatings obtained by matrix assisted pulsed laser evaporation

    Rusen, L. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, 077125, Magurele, Bucharest (Romania); Mustaciosu, C. [Horia Hulubei National Institute of Physics and Nuclear Engineering - IFIN HH, Magurele, Bucharest (Romania); Mitu, B.; Filipescu, M.; Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, 077125, Magurele, Bucharest (Romania); Dinca, V., E-mail: dinali@nipne.ro [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, 077125, Magurele, Bucharest (Romania)

    2013-08-01

    Adsorption of proteins and polysaccharides is known to facilitate microbial attachment and subsequent formation of biofilm on surfaces that ultimately results in its biofouling. Therefore, protein repellent modified surfaces are necessary to block the irreversible attachment of microorganisms. Within this context, the feasibility of using the Poly(ethylene glycol)-block-poly(ε-caprolactone) methyl ether (PEG-block-PCL Me) copolymer as potential protein-resistant coating was explored in this work. The films were deposited using Matrix Assisted Pulsed Laser Evaporation (MAPLE), a technique that allows good control of composition, thickness and homogeneity. The chemical and morphological characteristics of the films were examined using Fourier Transform Infrared Spectroscopy (FTIR), contact angle measurements and Atomic Force Microscopy (AFM). The FTIR data demonstrates that the functional groups in the MAPLE-deposited films remain intact, especially for fluences below 0.5 J cm{sup −2}. Optical Microscopy and AFM images show that the homogeneity and the roughness of the coatings are related to both laser parameters (fluence, number of pulses) and target composition. Protein adsorption tests were performed on the PEG-block-PCL Me copolymer coated glass and on bare glass surface as a control. The results show that the presence of copolymer as coating significantly reduces the adsorption of proteins.

  3. Multifunctional reduction-responsive SPIO&DOX-loaded PEGylated polymeric lipid vesicles for magnetic resonance imaging-guided drug delivery

    Wang, Sheng; Yang, Weitao; Du, Hongli; Guo, Fangfang; Wang, Hanjie; Chang, Jin; Gong, Xiaoqun; Zhang, Bingbo

    2016-04-01

    Multifunctional superparamagnetic iron-oxide (SPIO)-based nanoparticles have been emerging as candidate nanosystems for cancer diagnosis and therapy. Here, we report the use of reduction- responsive SPIO/doxorubicin (DOX)-loaded poly(ethylene glycol) monomethyl ether (PEG)ylated polymeric lipid vesicles (SPIO&DOX-PPLVs) as a novel theranostic system for tumor magnetic resonance imaging (MRI) diagnosis and controlled drug delivery. These SPIO&DOX-PPLVs are composed of SPIOs that function as MR contrast agents for tumor enhancement and PPLVs as polymer matrices for encapsulating SPIO and antitumor drugs. The in vitro characterizations show that the SPIO&DOX-PPLVs have nanosized structures (˜80 nm), excellent colloidal stability, good biocompatibility, as well as T 2-weighted MRI capability with a relatively high T 2 relaxivity (r 2 = 213.82 mM-1 s-1). In vitro drug release studies reveal that the release rate of DOX from the SPIO&DOX-PPLVs is accelerated in the reduction environment. An in vitro cellular uptake study and an antitumor study show that the SPIO&DOX-PPLVs have magnetic targeting properties and effective antitumor activity. In vivo studies show the SPIO&DOX-PPLVs have excellent T 2-weighted tumor targeted MRI capability, image-guided drug delivery capability, and high antitumor effects. These results suggest that the SPIO&DOX-PPLVs are promising nanocarriers for MRI diagnosis and cancer therapy applications.

  4. Preparation of composite poly(ether block amide) membrane for CO2 capture

    Lianjun Wang; Yang Li; Shuguang Li; Pengfei Ji; Chengzhang Jiang

    2014-01-01

    In this study, a poly(ether block amide) (Pebax 1657) composite membrane applied for CO2 capture was prepared by coating Pebax 1657 solution on polyacrylonitrile (PAN) ultrafiltration membrane. Ethanol/water mixture was used as the solvent of Pebax and the effects of ethanol/water mass ratios and Pebax concentration on the permeation properties of composite membrane were studied. To enhance the com-posite membrane permeance, the gutter layer, made from reactive amino silicone crosslinking with polydimethylsiloxane (PDMS), was de-signed. The influence of crosslinking degree of the gutter layer on membrane performance was investigated. As a result, a Pebax/amino-PDMS/PAN multilayer membrane with hexane resistance was developed, showing CO2 permeance of 350 GPU and CO2/N2 selectivity over 50. The blend of polyethylene glycol dimethyl ether (PEG-DME) with Pebax as coating material was studied to further improve the membrane performance. After being combined with PEG-DME additive, CO2 permeance of the final Pebax-PEG-DME/amino-PDMS/PAN composite membrane reached 400 GPU above with CO2/N2 selectivity over 65.

  5. Protein-resistant polymer coatings obtained by matrix assisted pulsed laser evaporation

    Rusen, L.; Mustaciosu, C.; Mitu, B.; Filipescu, M.; Dinescu, M.; Dinca, V.

    2013-08-01

    Adsorption of proteins and polysaccharides is known to facilitate microbial attachment and subsequent formation of biofilm on surfaces that ultimately results in its biofouling. Therefore, protein repellent modified surfaces are necessary to block the irreversible attachment of microorganisms. Within this context, the feasibility of using the Poly(ethylene glycol)-block-poly(ɛ-caprolactone) methyl ether (PEG-block-PCL Me) copolymer as potential protein-resistant coating was explored in this work. The films were deposited using Matrix Assisted Pulsed Laser Evaporation (MAPLE), a technique that allows good control of composition, thickness and homogeneity. The chemical and morphological characteristics of the films were examined using Fourier Transform Infrared Spectroscopy (FTIR), contact angle measurements and Atomic Force Microscopy (AFM). The FTIR data demonstrates that the functional groups in the MAPLE-deposited films remain intact, especially for fluences below 0.5 J cm-2. Optical Microscopy and AFM images show that the homogeneity and the roughness of the coatings are related to both laser parameters (fluence, number of pulses) and target composition. Protein adsorption tests were performed on the PEG-block-PCL Me copolymer coated glass and on bare glass surface as a control. The results show that the presence of copolymer as coating significantly reduces the adsorption of proteins.

  6. Photostable epoxy polymerized carbon quantum dots luminescent thin films and the performance study

    Zhang, Chang; Du, Lei; Liu, Cui; Li, Yunchuan; Yang, ZhenZhen; Cao, Yuan-Cheng

    High photostable epoxy polymerized carbon quantum dots (C-dots) luminescent thin films were prepared and their performances were compared with the CdTe quantum dots (QDs). First, water soluble C-dots (λem = 543.60 nm) were synthesized. Poly (ethylene glycol) diglycidyl ether (PEG) and diaminooctane were used as the polymer matrix to make the epoxy resin films. FT-IR spectra showed that there were vibration at 3448 cm-1 and 1644 cm-1 which contributed to -OH and -NH respectively. SEM observations showed that the polymerizations of the films were uniform and there were no structure defects. Mechanical tests showed the tensile modulus of C-dots composite films were 4.6, 4.9, 6.4 and 7.8 MPa respectively with corresponding 0%, 1%, 2% and 5% mass fraction of C-dots, while the tensile modulus of CdTe QDs films were 4.6 MPa under the same mass fraction of CdTe QDs. Compared with semiconductor QDs, the decay of quantum yield were 5% and 10% for the C-dots and CdTe QDs, respectively. The pictures in the continuous irradiation of 48 h showed that the C-dots film was more photostable. This study provides much helpful and profound towards the fluorescent enhancement films in the field of flexible displays.

  7. Miniaturizable Ion-Selective Arrays Based on Highly Stable Polymer Membranes for Biomedical Applications

    Mir, Mònica; Lugo, Roberto; Tahirbegi, Islam Bogachan; Samitier, Josep

    2014-01-01

    Poly(vinylchloride) (PVC) is the most common polymer matrix used in the fabrication of ion-selective electrodes (ISEs). However, the surfaces of PVC-based sensors have been reported to show membrane instability. In an attempt to overcome this limitation, here we developed two alternative methods for the preparation of highly stable and robust ion-selective sensors. These platforms are based on the selective electropolymerization of poly(3,4-ethylenedioxythiophene) (PEDOT), where the sulfur atoms contained in the polymer covalently interact with the gold electrode, also permitting controlled selective attachment on a miniaturized electrode in an array format. This platform sensor was improved with the crosslinking of the membrane compounds with poly(ethyleneglycol) diglycidyl ether (PEG), thus also increasing the biocompatibility of the sensor. The resulting ISE membranes showed faster signal stabilization of the sensor response compared with that of the PVC matrix and also better reproducibility and stability, thus making these platforms highly suitable candidates for the manufacture of robust implantable sensors. PMID:24999717

  8. Preparation of pH-sensitive amphiphilic block star polymers, their self-assembling characteristics and release behavior on encapsulated molecules

    Song, Xiaowan

    2016-05-28

    Poly(ethylene glycol) (PEG), a polymer with excellent biocompatibility, was widely used to form nanoparticles for drug delivery applications. In this paper, based on PEG, a series of pH-sensitive amphiphilic block star polymers of poly(ethylene glycol)-block-poly(ethoxy ethyl glycidyl ether) (PEG-b-PEEGE) with different hydrophobic length were synthesized by living anionic ring-opening polymerization method. The products were characterized using 1H NMR and gel permeation chromatography. These copolymers could self-assemble in aqueous solution to form micellar structure with controlled morphologies. Transmission electron microscopy showed that the nanoparticles are spherical or rodlike with different hydrophilic mass fractions. The pH response of polymeric aggregates from PEG-b-PEEGE was detected by fluorescence probe technique at different pH. A pH-dependent release behavior was observed and pH-responsiveness of PEG-b-PEEGE was affected by the hydrophobic block length. These results demonstrated that star-shaped polymers (PEG-b-PEEGE) are attractive candidates as anticancer drug delivery carriers. © 2016 Springer-Verlag Berlin Heidelberg

  9. Stimuli-Responsive Liposomes for Controlled Drug Delivery

    Li, Wengang

    2014-09-01

    Liposomes are promising drug delivery vesicles due to their biodegradibility, large volume and biocompatibility towards both hydrophilic and hydrophobic drugs. They suffer, however, from poor stability which limits their use in controlled delivery applications. Herein, a novel method was devised for modification of liposomes with small molecules, polymers or nanoparticles to afford stimuli responsive systems that release on demand and stay relatively stable in the absence of the trigger.. This dissertation discusses thermosensitive, pH sensitive, light sensitive and magnetically triggered liposomes that have been prepared for controlled drug delivery application. RAFT polymerization was utilized for the preparation of thermosensitive liposomes (Cholesterol-PNIPAm) and acid-labile liposomes (DOPE-PAA). With low Mw Cholesterol-PNIPAm, the thermosensitive liposomes proved to be effective for controlled release and decreased the cytotoxicity of PNIPAm by eliciting the polymer doses. By crosslinking the DOPE-PAA on liposome surface with acid-labile diamine linkers, DOPE-PAA liposomes were verified to be sensitive at low pH. The effects of polymer structures (linear or hyperbranched) have also been studied for the stability and release properties of liposomes. Finally, a dual-responsive Au@SPIO embedded liposome hybrid (ALHs) was prepared with light-induced “on-and-off” function by photo-thermal process (visible light) and instant release properties triggered by alternating magnetic field, respectively. The ALH system would be further applied into the cellular imaging field as MRI contrast agent.

  10. A reexamination of amino acids in lunar soils: Implications for the survival of exogenous organic material during impact delivery

    Brinton, Karen L. F.; Bada, Jeffrey L.

    1996-01-01

    Using a sensitive high performance liquid chromatography technique, we have analyzed both the hot water extract and the acid hydrolyzed hot water extract of lunar soil collected during the Apollo 17 mission. Both free amino acids and those derived from acid labile precursors are present at a level of roughly 15 ppb. Based on the D/L amino acid ratios, the free alanine and aspartic acid observed in the hot water extract can be entirely attributed to terrestrial biogenic contamination. However, in the acid labile fraction, precursors which yield amino acids are apparently present in the lunar soil. The amino acid distribution suggests that the precursor is probably solar wind implanted HCN. We have evaluated our results with regard to the meteoritic input of intact organic compounds to the moon based on an upper limit of ≤ 0.3 ppb for α-aminoisobutyric acid, a non-protein amino acid which does not generally occur in terrestrial organisms and which is not a major amino acid produced from HCN, but which is a predominant amino acid in many carbonaceous chondrites. We find that the survival of exogenous organic compounds during lunar impact is ≤ 0.8%. This result represents an example of minimum organic impact survivability. This is an important first step toward a better understanding of similar processes on Earth and on Mars, and their possible contribution to the budget of prebiotic organic compounds on the primitive Earth.

  11. Amphiphilic block copolymers bearing six-membered ortho ester ring in side chains as potential drug carriers: synthesis, characterization, and in vivo toxicity evaluation.

    Luo, Shi; Tao, Yangyang; Tang, Rupei; Wang, Rui; Ji, Weihang; Wang, Chun; Zhao, Youliang

    2014-07-01

    A new type of amphiphilic block copolymers, poly(ethylene glycol)-block-poly(2-methyl-acrylicacid 2-methoxy-5-methyl-[1,3]dioxin-5-ylmethyl ester) (PEG-b-PMME), bearing acid-labile six-membered ortho ester rings in side chains was synthesized by reversible addition-fragmentation chain-transfer polymerization, and the influence of chain length of the hydrophobic PMME block on micelle properties was investigated. The PEG-b-PMME micelles were stable in aqueous buffer at physiological pH with a low critical micelle concentration. Nile Red as a model drug was encapsulated into the micelles to explore the release profiles. The Nile Red-loaded polymeric micelles showed rapid release of Nile Red in weakly acidic environments (pH 5) but slow release under physiological condition (pH 7.4), due to different hydrolysis rate of ortho ester side chains of PEG-b-PMME. The Paclitaxel (PTX)-loaded micelles retained potency in killing lung cancer cells (A549), compared with the free PTX. No obvious toxicity was found in vitro and in vivo after intraperitoneal injection of the micelles, which confirms that the PEG-b-PMME micelles with unique acid-labile characteristic have great potential as nano-scaled carriers for drug delivery.

  12. PEG-b-AGE Polymer Coated Magnetic Nanoparticle Probes with Facile Functionalization and Anti-fouling Properties for Reducing Non-specific Uptake and Improving Biomarker Targeting.

    Li, Yuancheng; Lin, Run; Wang, Liya; Huang, Jing; Wu, Hui; Cheng, Guojun; Zhou, Zhengyang; MacDonald, Tobey; Yang, Lily; Mao, Hui

    2015-05-07

    Non-specific surface adsorption of bio-macromolecules (e.g. proteins) on nanoparticles, known as biofouling, and the uptake of nanoparticles by the mononuclear phagocyte system (MPS) and reticuloendothelial system (RES) lead to substantial reduction in the efficiency of target-directed imaging and delivery in biomedical applications of engineered nanomaterials in vitro and in vivo. In this work, a novel copolymer consisting of blocks of poly ethylene glycol and allyl glycidyl ether (PEG-b-AGE) was developed for coating magnetic iron oxide nanoparticles (IONPs) to reduce non-specific protein adhesion that leads to formation of "protein corona" and uptake by macrophages. The facile surface functionalization was demonstrated by using targeting ligands of a small peptide of RGD or a whole protein of transferrin (Tf). The PEG-b-AGE coated IONPs exhibited anti-biofouling properties with significantly reduced protein corona formation and non-specific uptake by macrophages before and after the surface functionalization, thus improving targeting of RGD-conjugated PEG-b-AGE coated IONPs to integrins in U87MG glioblastoma and MDA-MB-231 breast cancer cells that overexpress αvβ3 integrins, and Tf-conjugated PEG-b-AGE coated IONPs to transferrin receptor (TfR) in D556 and Daoy medulloblastoma cancer cells with high overexpression of transferrin receptor, compared to respective control cell lines. Magnetic resonance imaging (MRI) of cancer cells treated with targeted IONPs with or without anti-biofouling PEG-b-AGE coating polymers demonstrated the target specific MRI contrast change using anti-biofouling PEG-b-AGE coated IONP with minimal off-targeted background compared to the IONPs without anti-biofouling coating, promising the highly efficient active targeting of nanoparticle imaging probes and drug delivery systems and potential applications of imaging quantification of targeted biomarkers.

  13. Poly(ethylene glycol-cholesterol inhibits L-type Ca2+ channel currents and augments voltage-dependent inactivation in A7r5 cells.

    Rikuo Ochi

    Full Text Available Cholesterol distributes at a high density in the membrane lipid raft and modulates ion channel currents. Poly(ethylene glycol cholesteryl ether (PEG-cholesterol is a nonionic amphipathic lipid consisting of lipophilic cholesterol and covalently bound hydrophilic PEG. PEG-cholesterol is used to formulate lipoplexes to transfect cultured cells, and liposomes for encapsulated drug delivery. PEG-cholesterol is dissolved in the external leaflet of the lipid bilayer, and expands it to flatten the caveolae and widen the gap between the two leaflets. We studied the effect of PEG-cholesterol on whole cell L-type Ca(2+ channel currents (I(Ca,L recorded from cultured A7r5 arterial smooth muscle cells. The pretreatment of cells with PEG-cholesterol decreased the density of ICa,L and augmented the voltage-dependent inactivation with acceleration of time course of inactivation and negative shift of steady-state inactivation curve. Methyl-β-cyclodextrin (MβCD is a cholesterol-binding oligosaccharide. The enrichment of cholesterol by the MβCD:cholesterol complex (cholesterol (MβCD caused inhibition of I(Ca,L but did not augment voltage-dependent inactivation. Incubation with MβCD increased I(Ca,L, slowed the time course of inactivation and shifted the inactivation curve to a positive direction. Additional pretreatment by a high concentration of MβCD of the cells initially pretreated with PEG-cholesterol, increased I(Ca,L to a greater level than the control, and removed the augmented voltage-dependent inactivation. Due to the enhancement of the voltage-dependent inactivation, PEG-cholesterol inhibited window I(Ca,L more strongly as compared with cholesterol (MβCD. Poly(ethylene glycol conferred to cholesterol the efficacy to induce sustained augmentation of voltage-dependent inactivation of I(Ca,L.

  14. An experimental design approach to the chemical characterisation of pectin polysaccharides extracted from Cucumis melo Inodorus.

    Denman, Laura J; Morris, Gordon A

    2015-03-06

    Extracted pectins have been utilised in a number of applications in both the food and pharmaceutical industries where they are generally used as gelling agents, thickeners and stabilisers, although a number of pectins have been shown to be bioactive. These functional properties will depend upon extraction conditions. A statistical experimental design approach was used to study the effects of extraction conditions pH, time and temperature on pectins extracted from Cucumis melo Inodorus. The results show that the chemical composition is very sensitive to these conditions and that this has a great influence on for example the degree of branching. Higher temperatures, lower pHs and longer extraction times lead to a loss of the more acid labile arabinofuranose residues present on the pectin side chain. The fitting of regression equations relating yield and composition to extraction conditions can therefore lead to tailor-made pectins for specific properties and/or applications.

  15. [Clinical and pharmacological aspects of pancreatic enzyme substitution therapy].

    Löser, C; Fölsch, U R

    1991-03-01

    The adequate therapy of pancreatic enzyme replacement in patients with exocrine pancreatic insufficiency is still a difficult clinical problem especially in patients following pancreatectomys, with chronic alcoholic pancreatitis or cystic fibrosis. The substitution of lipase to eliminate steatorrhoea is the most important aim but due to its acid lability even the most serious problem in pancreatic enzyme replacement therapy. Various different medications are meanwhile available: conventional preparations from porcine pancreatin or fungal enzymes as rizolipase, enteric-coated tablets or even enteric-coated microspheres or adjunctive therapy with H2-receptor antagonists. While dosage requirements vary widely and therefore have to be tried out individually, the choice of the adequate preparation should be influenced by the realization of the physiological and pathophysiological characteristics of the individual patient and the pharmaceutical characteristics of the different supplements. The advantages and disadvantages of the various medications for enzyme replacement therapy in patients with exocrine pancreatic insufficiency are reviewed in this article.

  16. Peptide-Decorated Gold Nanoparticles as Functional Nano-Capping Agent of Mesoporous Silica Container for Targeting Drug Delivery.

    Chen, Ganchao; Xie, Yusheng; Peltier, Raoul; Lei, Haipeng; Wang, Ping; Chen, Jun; Hu, Yi; Wang, Feng; Yao, Xi; Sun, Hongyan

    2016-05-11

    A stimuli-responsive drug delivery system (DDS) with bioactive surface is constructed by end-capping mesoporous silica nanoparticles (MSNs) with functional peptide-coated gold nanoparticles (GNPs). MSNs are first functionalized with acid-labile α-amide-β-carboxyl groups to carry negative charges, and then capped with positively charged GNPs that are decorated with oligo-lysine-containing peptide. The resulting hybrid delivery system exhibits endo/lysosomal pH triggered drug release, and the incorporation of RGD peptide facilitates targeting delivery to αvβ3 integrin overexpressing cancer cells. The system can serve as a platform for preparing diversified multifunctional nanocomposites using various functional inorganic nanoparticles and bioactive peptides.

  17. Conjugation chemistry through acetals toward a dextran-based delivery system for controlled release of siRNA

    Cui, Lina

    2012-09-26

    New conjugation chemistry for polysaccharides, exemplified by dextran, was developed to enable the attachment of therapeutic or other functional moieties to the polysaccharide through cleavable acetal linkages. The acid-lability of the acetal groups allows the release of therapeutics under acidic conditions, such as that of the endocytic compartments of cells, regenerating the original free polysaccharide in the end. The physical and chemical behavior of these acetal groups can be adjusted by modifying their stereoelectronic and steric properties, thereby providing materials with tunable degradation and release rates. We have applied this conjugation chemistry in the development of water-soluble siRNA carriers, namely acetal-linked amino-dextrans, with various amine structures attached through either slow- or fast-degrading acetal linker. The carriers with the best combination of amine moieties and structural composition of acetals showed high in vitro transfection efficiency and low cytotoxicity in the delivery of siRNA. © 2012 American Chemical Society.

  18. Quantitation of sulfate and thiosulfate in clinical samples by ion chromatography.

    Cole, D E; Evrovski, J

    1997-11-21

    For assay of serum sulfate, quantitation by ion conductimetry after separation by anion-exchange chromatography is the method of choice. In comparison to classical barium precipitation methods, chromatographic methods demonstrate increased precision, specificity and sensitivity, and they may be superior to spectrophotometric methods that rely on organic cation precipitation of sulfate. The increased sensitivity and specificity, as well as the inherent capacity of chromatographic methods for simultaneous determination of other anions, has led to its increasing use in the determination of excreted sulfate in clinical profiles of urinary anion composition. Ion chromatography can also be used to quantitate free sulfate in other clinical samples, including cerebrospinal fluid, sweat, saliva, breast milk and human tissues. Finally, ion chromatography shows promise as a more precise and sensitive method for measurement of total acid-labile sulfoesters and thiosulfate.

  19. Effect of periodontal root planing on dentin permeability.

    Fogel, H M; Pashley, D H

    1993-10-01

    The purpose of this study was to quantitate the effects of root planing on the permeability of human root dentin in vitro. Unerupted 3rd molars were used. The crowns were removed and longitudinal slices made of the root. The hydraulic conductance of the root dentin was measured before and after root planing, acid etching and potassium oxalate application using a fluid filtration method. The results showed that root planing creates a smear layer that reduces the permeability of the underlying dentin. However, this smear layer is acid labile. Thus, root planing may ultimately cause increased dentin permeability and the associated sequelae of sensitive dentin, bacterial invasion of tubules, reduced periodontal reattachment and pulpal irritation.

  20. Formulation, Development and Evaluation of delayed release capsules of Duloxetine Hydrochloride made of different Enteric Polymers

    Pallavi Yerramsetty

    2012-03-01

    Full Text Available Delayed release systems have acquired a centre stage in the arena of pharmaceutical research and development. The present study involves formulation and evaluation of Duloxetine Hydrochloride delayed release capsules. Duloxetine Hydrochloride is an acid labile drug. It degrades in the acidic environment of the stomach thus leading to therapeutic inefficacy. Therefore it is necessary to bypass the acidic pH of the stomach which can be achieved by formulating delayed release dosage form by using different enteric polymers. Protection of drug from acidic environment is done by coating the drug with enteric polymers by using suspension layering technique in Fluidized bed processor (FBP with different enteric polymers like HPMCAS (Hydroxy Propyl Methyl Cellulose Acetate Succinate, Acryl EZE and HPMCP (Hydroxy propyl methyl cellulose phthalate.The formulation (E12 of delayed release capsules of Duloxetine Hydrochloride containing HPMCP (HP-55: HP- 50 as enteric polymer can be taken as optimized

  1. Rational Design of a Carrier Protein for the Production of Recombinant Toxic Peptides in Escherichia coli

    Pizzo, Elio; Varcamonti, Mario; Zanfardino, Anna; Sgambati, Valeria; Di Maro, Antimo; Carpentieri, Andrea; Izzo, Viviana; Di Donato, Alberto; Cafaro, Valeria; Notomista, Eugenio

    2016-01-01

    Commercial uses of bioactive peptides require low cost, effective methods for their production. We developed a new carrier protein for high yield production of recombinant peptides in Escherichia coli very well suited for the production of toxic peptides like antimicrobial peptides. GKY20, a short antimicrobial peptide derived from the C-terminus of human thrombin, was fused to the C-terminus of Onconase, a small ribonuclease (104 amino acids), which efficiently drove the peptide into inclusion bodies with very high expression levels (about 200–250 mg/L). After purification of the fusion protein by immobilized metal ion affinity chromatography, peptide was obtained by chemical cleavage in diluted acetic acid of an acid labile Asp-Pro sequence with more than 95% efficiency. To improve peptide purification, Onconase was mutated to eliminate all acid labile sequences thus reducing the release of unwanted peptides during the acid cleavage. Mutations were chosen to preserve the differential solubility of Onconase as function of pH, which allows its selective precipitation at neutral pH after the cleavage. The improved carrier allowed the production of 15–18 mg of recombinant peptide per liter of culture with 96–98% purity without the need of further chromatographic steps after the acid cleavage. The antimicrobial activity of the recombinant peptide, with an additional proline at the N-terminus, was tested on Gram-negative and Gram-positive strains and was found to be identical to that measured for synthetic GKY20. This finding suggests that N-terminal proline residue does not change the antimicrobial properties of recombinant (P)GKY20. The improved carrier, which does not contain cysteine and methionine residues, Asp-Pro and Asn-Gly sequences, is well suited for the production of peptides using any of the most popular chemical cleavage methods. PMID:26808536

  2. Rational Design of a Carrier Protein for the Production of Recombinant Toxic Peptides in Escherichia coli.

    Katia Pane

    Full Text Available Commercial uses of bioactive peptides require low cost, effective methods for their production. We developed a new carrier protein for high yield production of recombinant peptides in Escherichia coli very well suited for the production of toxic peptides like antimicrobial peptides. GKY20, a short antimicrobial peptide derived from the C-terminus of human thrombin, was fused to the C-terminus of Onconase, a small ribonuclease (104 amino acids, which efficiently drove the peptide into inclusion bodies with very high expression levels (about 200-250 mg/L. After purification of the fusion protein by immobilized metal ion affinity chromatography, peptide was obtained by chemical cleavage in diluted acetic acid of an acid labile Asp-Pro sequence with more than 95% efficiency. To improve peptide purification, Onconase was mutated to eliminate all acid labile sequences thus reducing the release of unwanted peptides during the acid cleavage. Mutations were chosen to preserve the differential solubility of Onconase as function of pH, which allows its selective precipitation at neutral pH after the cleavage. The improved carrier allowed the production of 15-18 mg of recombinant peptide per liter of culture with 96-98% purity without the need of further chromatographic steps after the acid cleavage. The antimicrobial activity of the recombinant peptide, with an additional proline at the N-terminus, was tested on Gram-negative and Gram-positive strains and was found to be identical to that measured for synthetic GKY20. This finding suggests that N-terminal proline residue does not change the antimicrobial properties of recombinant (PGKY20. The improved carrier, which does not contain cysteine and methionine residues, Asp-Pro and Asn-Gly sequences, is well suited for the production of peptides using any of the most popular chemical cleavage methods.

  3. The pharmacokinetics and metabolism of 14C/13C-labeled ortho-phenylphenol formation following dermal application to human volunteers.

    Timchalk, C; Selim, S; Sangha, G; Bartels, M J

    1998-08-01

    1. The pharmacokinetics and metabolism of uniformly labeled 14C/13C-ortho-phenylphenol (OPP) were followed in six human male volunteers given a single 8 h dermal dose of 6 microg OPP/kg body weight formulated as a 0.4% (w/v) solution in isopropyl alcohol. The application site was covered with a non-occlusive dome allowing free movement of air, but preventing the loss of radioactivity due to physical contact. At 8 h post-exposure the non-occlusive dome was removed, the dose site was wiped with isopropyl alcohol containing swabs and the skin surface repeatedly stripped with tape. Blood specimens, urine, and feces were collected from each volunteer over a 5 day post-exposure period and were analyzed for radioactivity and metabolites (urine only). 2. Following dermal application, peak plasma levels of radioactivity were obtained within 4 h post-exposure and rapidly declined with virtually all of the absorbed dose rapidly excreted into the urine within 24 h post-exposure. A one-compartment pharmacokinetic model was used to describe the time-course of OPP absorption and clearance in male human volunteers. Approximately 43% of the dermally applied dose was absorbed through the skin with an average absorption half-life of 10 h. Once absorbed the renal clearance of OPP was rapid with an average half-life of 0.8 h. The rate limiting step for renal clearance was the relatively slower rate of dermal absorption; therefore the pharmacokinetics of OPP in humans was described by a 'flip-flop' single compartment model. Overall, the pharmacokinetics were similar between individuals, and the model parameters were in excellent agreement with the experimental data. 3. Approximately 73% of the total urinary radioactivity was accounted for as free OPP, OPP-sulfate and OPP-glucuronide conjugates. The sulfate conjugate was the major metabolite (approximately 69%). Therefore, total urinary OPP equivalents (acid-labile conjugates+free OPP) can be used to estimate the systemically absorbed

  4. Doxorubicin conjugated functionalizable carbon dots for nucleus targeted delivery and enhanced therapeutic efficacy

    Yang, Lei; Wang, Zheran; Wang, Ju; Jiang, Weihua; Jiang, Xuewei; Bai, Zhaoshi; He, Yunpeng; Jiang, Jianqi; Wang, Dongkai; Yang, Li

    2016-03-01

    Carbon dots (CDs) have shown great potential in imaging and drug/gene delivery applications. In this work, CDs functionalized with a nuclear localization signal peptide (NLS-CDs) were employed to transport doxorubicin (DOX) into cancer cells for enhanced antitumor activity. DOX was coupled to NLS-CDs (DOX-CDs) through an acid-labile hydrazone bond, which was cleavable in the weakly acidic intracellular compartments. The cytotoxicity of DOX-CD complexes was evaluated by the MTT assay and the cellular uptake was monitored using flow cytometry and confocal laser scanning microscopy. Cell imaging confirmed that DOX-CDs were mainly located in the nucleus. Furthermore, the complexes could efficiently induce apoptosis in human lung adenocarcinoma A549 cells. The in vivo therapeutic efficacy of DOX-CDs was investigated in an A549 xenograft nude mice model and the complexes exhibited an enhanced ability to inhibit tumor growth compared with free DOX. Thus, the DOX-CD conjugates may be exploited as promising drug delivery vehicles in cancer therapy.Carbon dots (CDs) have shown great potential in imaging and drug/gene delivery applications. In this work, CDs functionalized with a nuclear localization signal peptide (NLS-CDs) were employed to transport doxorubicin (DOX) into cancer cells for enhanced antitumor activity. DOX was coupled to NLS-CDs (DOX-CDs) through an acid-labile hydrazone bond, which was cleavable in the weakly acidic intracellular compartments. The cytotoxicity of DOX-CD complexes was evaluated by the MTT assay and the cellular uptake was monitored using flow cytometry and confocal laser scanning microscopy. Cell imaging confirmed that DOX-CDs were mainly located in the nucleus. Furthermore, the complexes could efficiently induce apoptosis in human lung adenocarcinoma A549 cells. The in vivo therapeutic efficacy of DOX-CDs was investigated in an A549 xenograft nude mice model and the complexes exhibited an enhanced ability to inhibit tumor growth compared

  5. Fluorescent polymeric assemblies as stimuli-responsive vehicles for drug controlled release and cell/tissue imaging

    Chang, Ying; Li, Yang; Yu, Shirong; Mao, Jie; Liu, Cheng; Li, Qi; Yuan, Conghui; He, Ning; Luo, Weiang; Dai, Lizong

    2015-01-01

    Polymer assemblies with good biocompatibility, stimuli-responsive properties and clinical imaging capability are desirable carriers for future biomedical applications. Herein, we report on the synthesis of a novel anthracenecarboxaldehyde-decorated poly(N-(4-aminophenyl) methacryl amide-oligoethyleneglycolmonomethylether methacrylate) (P(MAAPAC-MAAP-MAPEG)) copolymer, comprising fluorescent chromophore and acid-labile moiety. This copolymer can assemble into micelles in aqueous solution and shows a spherical shape with well-defined particle size and narrow particle size distribution. The pH-responsive property of the micelles has been evaluated by the change of particle size and the controlled release of guest molecules. The intrinsic fluorescence property endows the micelles with excellent cell/tissue imaging capability. Cell viability evaluation with human hepatocellular carcinoma BEL-7402 cells demonstrates that the micelles are nontoxic. The cellular uptake of the micelles indicates a time-dependent behavior. The H22-tumor bearing mice treated with the micelles clearly exhibits the tumor accumulation. These multi-functional nanocarriers may be of great interest in the application of drug delivery.

  6. Novel lansoprazole-loaded nanoparticles for the treatment of gastric acid secretion-related ulcers: in vitro and in vivo pharmacokinetic pharmacodynamic evaluation.

    Alai, Milind; Lin, Wen Jen

    2014-05-01

    The objective of this study is to combine nanoparticle design and enteric coating technique to sustain the delivery of an acid-labile drug, lansoprazole (LPZ), in the treatment of acid reflux disorders. Lansoprazole-loaded Eudragit® RS100 nanoparticles (ERSNP-LPZ) as well as poly(lactic-co-glycolic acid) (PLGA) nanoparticles (PLGANP-LPZ) were prepared using a solvent evaporation/extraction method. The effects of nanoparticle charge and permeation enhancers on lansoprazole uptake was assessed in Caco-2 cells. The confocal microscopic images revealed the successful localization of nanoparticles in the cytoplasm of Caco-2 cells. The cellular uptake of positively charged Eudragit nanoparticles was significantly higher than that of negatively charged PLGA nanoparticles, which were enhanced by sodium caprate via the transcellular pathway. Both types of nanoparticles exhibited sustained drug release behavior in vitro. The oral administration of enteric-coated capsules filled with nanoparticles sustained and prolonged the LPZ concentration up to 24 h in ulcer-induced Wistar rats, and 92.4% and 89.2% of gastric ulcers healed after a 7-day treatment with either EC-ERSNP1010-Na caprate or EC-PLGANP1005-Na caprate, respectively.

  7. Biocompatible and biodegradable fibrinogen microspheres for tumor-targeted doxorubicin delivery.

    Joo, Jae Yeon; Park, Gil Yong; An, Seong Soo A

    2015-01-01

    In the development of effective drug delivery carriers, many researchers have focused on the usage of nontoxic and biocompatible materials and surface modification with targeting molecules for tumor-specific drug delivery. Fibrinogen (Fbg), an abundant glycoprotein in plasma, could be a potential candidate for developing drug carriers because of its biocompatibility and tumor-targeting property via arginine-glycine-aspartate (RGD) peptide sequences. Doxorubicin (DOX), a chemotherapeutic agent, was covalently conjugated to Fbg, and the microspheres were prepared. Acid-labile and non-cleavable linkers were used for the conjugation of DOX to Fbg, resulting in an acid-triggered drug release under a mild acidic condition and a slow-controlled drug release, respectively. In vitro cytotoxicity tests confirmed low cytotoxicity in normal cells and high antitumor effect toward cancer cells. In addition, it was discovered that a longer linker could make the binding of cells to Fbg drug carriers easier. Therefore, DOX-linker-Fbg microspheres could be a suitable drug carrier for safer and effective drug delivery.

  8. MitoNEET Is a Uniquely Folded 2Fe-2S Outer Mitochondrial Membrane Protein Stabilized By Pioglitazone

    Paddock, M.L.; Wiley, S.E.; Axelrod, H.L.; Cohen, A.E.; Roy, M.; Abresch, E.C.; Capraro, D.; Murphy, A.N.; Nechushtai, R.; Dixon, J.E.; Jennings, P.A.; /UC, San Diego /SLAC, SSRL /Hebrew U.

    2007-10-19

    Iron-sulfur (Fe-S) proteins are key players in vital processes involving energy homeostasis and metabolism from the simplest to most complex organisms. We report a 1.5 Angstrom x-ray crystal structure of the first identified outer mitochondrial membrane Fe-S protein, mitoNEET. Two protomers intertwine to form a unique dimeric structure that constitutes a new fold to not only the {approx}650 reported Fe-S protein structures but also to all known proteins. We name this motif the NEET fold. The protomers form a two-domain structure: a {beta}-cap domain and a cluster-binding domain that coordinates two acid-labile 2Fe-2S clusters. Binding of pioglitazone, an insulin-sensitizing thiazolidinedione used in the treatment of type 2 diabetes, stabilizes the protein against 2Fe-2S cluster release. The biophysical properties of mitoNEET suggest that it may participate in a redox-sensitive signaling and/or in Fe-S cluster transfer.

  9. New method for the synthesis of N-methyl amino acids containing peptides by reductive methylation of amino groups on the solid phase.

    Kaljuste, K; Undén, A

    1993-08-01

    Primary amino groups on the model peptide Xaa-Ala-Pro-Lys(ClZ)-Tyr(2BrZ), synthesized on a p-methylbenzhydryl amine resin with conventional Boc/benzyl protective group strategy, were reacted with 4,4'-dimethoxydityl chloride in dichloromethane, resulting in the introduction of the dimethoxydityl group, which is an acid-labile N-alkyl type of protective group. The secondary amino groups thereby formed can be methylated by treating the peptide-resin with formaldehyde and sodium cyanoborohydride in N,N-dimethylformamide. After the removal of the dimethoxydityl group with trifluoroacetic acid, the resulting N-methylated amino acid residues with a free secondary amino groups are accessible for acylation with the next activated Boc amino acid. With this method majority of the 20 common amino acids can be monomethylated directly on the resin and, in most cases, with very low levels of the side reactions. In the cases where the complete methylation is difficult to achieve, the remaining primary amino groups can be selectively acylated in the presence of secondary amino groups with trimethylacetic acid 1-hydroxybenzotriazole ester. The method provides a convenient general route to synthesize N-methylated derivatives of most of the occurring and synthetic amino acids.

  10. Interferon response in normal and Aleutian disease virus-infected mink.

    Wiedbrauk, D L; Hadlow, W J; Ewalt, L C; Lodmell, D L

    1986-08-01

    Studies were done to determine whether differences in interferon production are responsible for the resistance of pastel mink to Aleutian disease. The abilities of normal pastel and sapphire mink to produce interferon when inoculated with either Newcastle disease virus or a synthetic polyribonucleotide, poly (I):poly (C), were identical, even to the production of a novel, acid-labile interferon. The resistance of pastel mink to Aleutian disease did not correlate with interferon production, because neither sapphire nor pastel mink produced detectable amounts of interferon when infected with either the Pullman strain of Aleutian disease virus (ADV) or the highly virulent Utah I strain. Sapphire mink infected with the Pullman strain responded normally to poly (I):poly (C) early in the course of the disease, but interferon production was impaired late, when the mink were hypergammaglobulinemic and had renal, vascular, and hepatic lesions. These data suggest that ADV Pullman neither stimulates nor interferes with interferon production in infected mink and may represent a mechanism whereby ADV can more readily establish infection.

  11. Self-assembled micelles composed of doxorubicin conjugated Y-shaped PEG-poly(glutamic acid)2 copolymers via hydrazone linkers.

    Sui, Bowen; Xu, Hui; Jin, Jian; Gou, Jingxin; Liu, Jingshuo; Tang, Xing; Zhang, Yu; Xu, Jinghua; Zhang, Hongfeng; Jin, Xiangqun

    2014-08-11

    In this work, micelles composed of doxorubicin-conjugated Y-shaped copolymers (YMs) linked via an acid-labile linker were constructed. Y-shaped copolymers of mPEG-b-poly(glutamate-hydrazone-doxorubicin)2 and linear copolymers of mPEG-b-poly(glutamate-hydrazone-doxorubicin) were synthesized and characterized. Particle size, size distribution, morphology, drug loading content (DLC) and drug release of the micelles were determined. Alterations in size and DLC of the micelles could be achieved by varying the hydrophobic block lengths. Moreover, at fixed DLCs, YMs showed a smaller diameter than micelles composed of linear copolymers (LMs). Also, all prepared micelles showed sustained release behaviors under physiological conditions over 72 h. DOX loaded in YMs was released more completely, with 30% more drug released in acid. The anti-tumor efficacy of the micelles against HeLa cells was evaluated by MTT assays, and YMs exhibited stronger cytotoxic effects than LMs in a dose- and time-dependent manner. Cellular uptake studied by CLSM indicated that YMs and LMs were readily taken up by HeLa cells. According to the results of this study, doxorubicin-conjugated Y-shaped PEG-(polypeptide)2 copolymers showed advantages over linear copolymers, like assembling into smaller nanoparticles, faster drug release in acid, which may correspond to higher cellular uptake and enhanced extracellular/intracellular drug release, indicating their potential in constructing nano-sized drug delivery systems.

  12. Review article: similarities and differences among delayed-release proton-pump inhibitor formulations.

    Horn, J R; Howden, C W

    2005-12-01

    Proton-pump inhibitors are acid-labile, and require an enteric coating to protect them from degradation in the stomach when given orally. However, this leads to delayed absorption and onset of action of the proton-pump inhibitor. This article aims to review the similarities and differences between the various formulations of delayed release proton-pump inhibitors. Delayed-release omeprazole and delayed-release lansoprazole have been suspended in sodium bicarbonate for tube administration; however, for omeprazole, absorption is further impaired and antisecretory effects are disappointing. Although such formulations may be more convenient for clinical use in certain patient groups, absorption of the proton-pump inhibitor is still influenced by residual enteric coating. There are few differences among the currently available delayed-release proton-pump inhibitors with respect to their pharmacodynamic effects during chronic administration. There are minor formulation-based pharmacokinetic differences among these agents, primarily reflected in their bioavailability following the first few doses. Differences in bioavailability may explain slight differences in the rate of onset of maximal antisecretory effect. However, minor pharmacodynamic and pharmacokinetic differences are not associated with meaningful differences in clinical outcomes.

  13. Determination of organochlorines, polychlorinated biphenyls and polybrominated diphenyl ethers in human hair: estimation of external and internal exposure.

    Lu, Dasheng; Feng, Chao; Lin, Yuanjie; Wang, Dongli; Ip, Ho Sai Simon; Qiu, Xinlei; Wang, Guoquan; She, Jianwen

    2014-11-01

    A novel method was developed for the analysis of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in human hair samples. External contaminants of hair were extracted with acetone under sonication, while washed hair was further hydrolyzed in formic acid and acetone (1:4, v/v) with microwave assisted extraction (MAE) for internal contaminant measurements. Both internal and external extracts were cleaned up with gel permeation chromatography (GPC) and then solid phase extraction (SPE), before analyzed by a large volume injection-gas chromatography-tandem mass spectrometry (LVI-GC-MS/MS) using triple quadruple mass analyzer. Good linearity (R(2)⩾ 0.996) was established within a concentration range between 0.1 and 100 ng mL(-)(1) among all target analytes. The method was validated for accuracy, precision and sensitivity. The developed method is intended to be cost effective and robust for the routine human hair analysis of PCBs, PBDEs and OCPs including acid-labile OCPs. The described method has been applied in pilot biomonitoring study and the preliminary data suggested that the contaminant profiles with the use of partial least-squares analysis discriminant analysis (PLA-DA) could be useful in differentiating external and internal exposure.

  14. Presence of amylose crystallites in parboiled rice.

    Lamberts, Lieve; Gomand, Sara V; Derycke, Veerle; Delcour, Jan A

    2009-04-22

    Mildly, intermediately, and severely parboiled Jacinto [16% free amylose (FAM) content] and Puntal (26% FAM content) rice samples were submitted to differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). DSC thermograms revealed ungelatinized starch only in mildly parboiled rices and retrograded amylopectin in all parboiled samples. Amylose crystallites were present in intermediately and severely parboiled samples but could not be detected due to their high melting temperature. Nonparboiled and parboiled rice DSC profiles showed only type I and type II amylose-lipid complexes, respectively. Intermediately and severely parboiled rice showed a clear V(h)-type (crystalline amylose-lipid complexes) with a superimposed B-type (retrograded amylopectin and/or amylose crystallites) pattern. The mildly parboiled samples showed a mix of A- (native starch crystallites) and V(h)-type patterns (Puntal) and A-, V(h)-, and B-type patterns (Jacinto). Mild acid hydrolysis destroyed the acid labile retrograded amylopectin crystallites and increased the relative abundance of amylose crystallites. Indeed, acid-hydrolyzed intermediately and severely parboiled samples of both cultivars showed a clear B-type diffraction pattern conclusively showing, for the first time, the presence of amylose crystallites. The melting temperature of the amylose crystallites was ca. 135 degrees C, and melting peaks were visible in the DSC thermograms of the intermediately and severely parboiled samples. Their levels depended on the degree of parboiling and FAM content.

  15. Towards practical Baeyer-Villiger-monooxygenases: design of cyclohexanone monooxygenase mutants with enhanced oxidative stability.

    Opperman, Diederik J; Reetz, Manfred T

    2010-12-10

    Baeyer-Villiger monooxygenases (BVMOs) catalyze the conversion of ketones and cyclic ketones into esters and lactones, respectively. Cyclohexanone monooxygenase (CHMO) from Acinetobacter sp. NCIMB 9871 is known to show an impressive substrate scope as well as exquisite chemo-, regio-, and enantioselectivity in many cases. Large-scale synthetic applications of CHMO are hampered, however, by the instability of the enzyme. Oxidation of cysteine and methionine residues contributes to this instability. Designed mutations of all the methionine and cysteine residues in the CHMO wild type (WT) showed that the amino acids labile towards oxidation are mostly either surface-exposed or located within the active site, whereas the two methionine residues identified for thermostabilization are buried within the folded protein. Combinatorial mutations gave rise to two stabilized mutants with either oxidative or thermal stability, without compromising the activity or stereoselectivity of the enzyme. The most oxidatively stabilized mutant retained nearly 40 % of its activity after incubation with H(2)O(2) (0.2 M), whereas the wild-type enzyme's activity was completely abolished at concentrations as low as 5 mM H(2)O(2). We propose that oxidation-stable mutants might well be a "prerequisite" for thermostabilization, because laboratory-evolved thermostability in CHMO might be masked by a high degree of oxidation instability.

  16. Fine-tuning of charge-conversion polymer structure for efficient endosomal escape of siRNA-loaded calcium phosphate hybrid micelles.

    Maeda, Yoshinori; Pittella, Frederico; Nomoto, Takahiro; Takemoto, Hiroyasu; Nishiyama, Nobuhiro; Miyata, Kanjiro; Kataoka, Kazunori

    2014-07-01

    For efficient delivery of siRNA into the cytoplasm, a smart block copolymer of poly(ethylene glycol) and charge-conversion polymer (PEG-CCP) is developed by introducing 2-propionic-3-methylmaleic (PMM) amide as an anionic protective group into side chains of an endosome-disrupting cationic polyaspartamide derivative. The PMM amide moiety is highly susceptible to acid hydrolysis, generating the parent cationic polyaspartamide derivative at endosomal acidic pH 5.5 more rapidly than a previously synthesized cis-aconitic (ACO) amide control. The PMM-based polymer is successfully integrated into a calcium phosphate (CaP) nanoparticle with siRNA, constructing PEGylated hybrid micelles (PMM micelles) having a sub-100 nm size at extracellular neutral pH 7.4. Ultimately, PMM micelles achieve the significantly higher gene silencing efficiency in cultured cancer cells, compared to ACO control micelles, probably due to the efficient endosomal escape of the PMM micelles. Thus, it is demonstrated that fine-tuning of acid-labile structures in CCP improves the delivery performance of siRNA-loaded nanocarriers.

  17. Extraction of copper from an oxidized (lateritic) ore using bacterially catalysed reductive dissolution.

    Nancucheo, Ivan; Grail, Barry M; Hilario, Felipe; du Plessis, Chris; Johnson, D Barrie

    2014-01-01

    An oxidized lateritic ore which contained 0.8 % (by weight) copper was bioleached in pH- and temperature-controlled stirred reactors under acidic reducing conditions using pure and mixed cultures of the acidophilic chemolithotrophic bacterium Acidithiobacillus ferrooxidans. Sulfur was provided as the electron donor for the bacteria, and ferric iron present in goethite (the major ferric iron mineral present in the ore) acted as electron acceptor. Significantly more copper was leached by bacterially catalysed reductive dissolution of the laterite than in aerobic cultures or in sterile anoxic reactors, with up to 78 % of the copper present in the ore being extracted. This included copper that was leached from acid-labile minerals (chiefly copper silicates) and that which was associated with ferric iron minerals in the lateritic ore. In the anaerobic bioreactors, soluble iron in the leach liquors was present as iron (II) and copper as copper (I), but both metals were rapidly oxidized (to iron (III) and copper (II)) when the reactors were aerated. The number of bacteria added to the reactors had a critical role in dictating the rate and yield of copper solubilised from the ore. This work has provided further evidence that reductive bioprocessing, a recently described approach for extracting base metals from oxidized deposits, has the potential to greatly extend the range of metal ores that can be biomined.

  18. Stimulation of the 150-kilodalton insulin-like growth factor-binding protein-3 ternary complex by continuous and pulsatile patterns of growth hormone (GH) administration in GH-deficient patients

    Laursen, Torben; Flyvbjerg, Allan; Jørgensen, Jens Otto Lunde

    2000-01-01

    Abstract In the circulation insulin-like growth factor I (IGF-I), IGF-binding protein 3 (IGFBP-3), and the acid-labile subunit (ALS) form a 150-kDa ternary complex that is of importance for the regulation of IGF-I bioactivity. GH administration is known to increase each of the single components...... of the ternary complex, and in GH-deficient rats formation of the 150-kDa complex is induced more by continuous than by pulsatile GH patterns. The aim of the present studies was to study the effects of the GH administration pattern on the formation of the 150-kDa ternary complex in humans. A fixed total GH dose...... (2 IU/m2-24 h) was administered iv randomly as 1) continuous infusion or 2) eight bolus injections to five GH-deficient patients over a period of 24 h. GH administration significantly increased serum IGF-I and IGFBP-3 levels and the IGF-I/IGFBP-3 ratio. IGF-I levels increased most pronouncedly after...

  19. Microwave-assisted solid-phase peptide synthesis of the 60-110 domain of human pleiotrophin on 2-chlorotrityl resin.

    Friligou, Irene; Papadimitriou, Evangelia; Gatos, Dimitrios; Matsoukas, John; Tselios, Theodore

    2011-05-01

    A fast and efficient microwave-assisted solid phase peptide synthesis (MW-SPPS) of a 51mer peptide, the main heparin-binding site (60-110) of human pleiotrophin (hPTN), using 2-chlorotrityl chloride resin (CLTR-Cl) following the 9-fluorenylmethyloxycarbonyl/tert-butyl (Fmoc/tBu) methodology and with the standard N,N'-diisopropylcarbodiimide/1-hydroxybenzotriazole (DIC/HOBt) coupling reagents, is described. An MW-SPPS protocol was for the first time successfully applied to the acid labile CLTR-Cl for the faster synthesis of long peptides (51mer peptide) and with an enhanced purity in comparison to conventional SPPS protocols. The synthesis of such long peptides is not trivial and it is generally achieved by recombinant techniques. The desired linear peptide was obtained in only 30 h of total processing time and in 51% crude yield, in which 60% was the purified product obtained with 99.4% purity. The synthesized peptide was purified by reversed phase high performance liquid chromatography (RP-HPLC) and identified by electrospray ionization mass spectrometry (ESI-MS). Then, the regioselective formation of the two disulfide bridges of hPTN 60-110 was successfully achieved by a two-step procedure, involving an oxidative folding step in dimethylsulfoxide (DMSO) to form the Cys(77)-Cys(109) bond, followed by iodine oxidation to form the Cys(67)-Cys(99) bond.

  20. Renal carbonic anhydrases are involved in the reabsorption of endogenous nitrite.

    Chobanyan-Jürgens, Kristine; Schwarz, Alexandra; Böhmer, Anke; Beckmann, Bibiana; Gutzki, Frank-Mathias; Michaelsen, Jan T; Stichtenoth, Dirk O; Tsikas, Dimitrios

    2012-02-15

    Nitrite (ONO(-)) exerts nitric oxide (NO)-related biological actions and its concentration in the circulation may be of particular importance. Nitrite is excreted in the urine. Hence, the kidney may play an important role in nitrite/NO homeostasis in the vasculature. We investigated a possible involvement of renal carbonic anhydrases (CAs) in endogenous nitrite reabsorption in the proximal tubule. The potent CA inhibitor acetazolamide was administered orally to six healthy volunteers (5 mg/kg) and nitrite was measured in spot urine samples before and after administration. Acetazolamide increased abruptly nitrite excretion in the urine, strongly suggesting that renal CAs are involved in nitrite reabsorption in healthy humans. Additional in vitro experiments support our hypothesis that nitrite reacts with CO(2), analogous to the reaction of peroxynitrite (ONOO(-)) with CO(2), to form acid-labile nitrito carbonate [ONOC(O)O(-)]. We assume that this reaction is catalyzed by CAs and that nitrito carbonate represents the nitrite form that is actively transported into the kidney. The significance of nitrite reabsorption in the kidney and the underlying mechanisms, notably a direct involvement of CAs in the reaction between nitrite and CO(2), remain to be elucidated.

  1. Characterization and reconstitution of the nucleational complex responsible for mineral formation by growth plate cartilage matrix vesicles.

    Wu, L N; Genge, B R; Sauer, G R; Wuthier, R E

    1996-01-01

    Previous studies revealed that matrix vesicles (MV) have an acid-labile nucleationally active core (ALNAC) essential for mineral formation; current studies were aimed at characterizing and reconstituting ALNAC. SDS-PAGE and FTIR analyses revealed the presence of lipids, proteins and amorphous calcium phosphate (ACP) in ALNAC. Extraction with chloroform-methanol reduced, but did not destroy MV calcification; treatment with chloroform-methanol-HCl destroyed all activity. This acidic solvent extracted the annexins, (phosphatidylserine (PS)-dependent Ca(2+)-binding proteins), and dissociated PS-Ca(2+)-Pi complexes present in the MV. Attempts to reconstitute ALNAC, centered on the Ca(2+)-PS-Pi complex. Various pure lipids, electrolytes and proteins were combined to form a synthetic nucleationally active complex (SNAC), analyzing the rate of Ca2+ uptake. Inclusion of phosphatidylethanolamine (PE) or sphingomyelin (SM) with PS, or Mg2+ or Zn2+ with Ca2+, strongly inhibited activity; incorporation of annexin V increased SNAC activity. Thus, approaching from either deconstruction or reconstruction, it appears that ALNAC is composed of ACP complexed with PS and the annexins. Other lipids, proteins and electrolytes modulate its activity. These findings also indicate how ALNAC must be formed in vivo.

  2. New complete genome sequences of human rhinoviruses shed light on their phylogeny and genomic features

    Zdobnov Evgeny M

    2007-07-01

    Full Text Available Abstract Background Human rhinoviruses (HRV, the most frequent cause of respiratory infections, include 99 different serotypes segregating into two species, A and B. Rhinoviruses share extensive genomic sequence similarity with enteroviruses and both are part of the picornavirus family. Nevertheless they differ significantly at the phenotypic level. The lack of HRV full-length genome sequences and the absence of analysis comparing picornaviruses at the whole genome level limit our knowledge of the genomic features supporting these differences. Results Here we report complete genome sequences of 12 HRV-A and HRV-B serotypes, more than doubling the current number of available HRV sequences. The whole-genome maximum-likelihood phylogenetic analysis suggests that HRV-B and human enteroviruses (HEV diverged from the last common ancestor after their separation from HRV-A. On the other hand, compared to HEV, HRV-B are more related to HRV-A in the capsid and 3B-C regions. We also identified the presence of a 2C cis-acting replication element (cre in HRV-B that is not present in HRV-A, and that had been previously characterized only in HEV. In contrast to HEV viruses, HRV-A and HRV-B share also markedly lower GC content along the whole genome length. Conclusion Our findings provide basis to speculate about both the biological similarities and the differences (e.g. tissue tropism, temperature adaptation or acid lability of these three groups of viruses.

  3. Supramolecular PEGylated Dendritic Systems as pH/Redox Dual-Responsive Theranostic Nanoplatforms for Platinum Drug Delivery and NIR Imaging.

    Li, Yunkun; Li, Yachao; Zhang, Xiao; Xu, Xianghui; Zhang, Zhijun; Hu, Cheng; He, Yiyan; Gu, Zhongwei

    2016-01-01

    Recently, self-assembling small dendrimers into supramolecular dendritic systems offers an alternative strategy to develop multifunctional nanoplatforms for biomedical applications. We herein report a dual-responsive supramolecular PEGylated dendritic system for efficient platinum-based drug delivery and near-infrared (NIR) tracking. With a refined molecular/supramolecular engineering, supramolecular dendritic systems were stabilized by bioreducible disulfide bonds and endowed with NIR fluorescence probes, and PEGylated platinum derivatives coordinated onto the abundant peripheral groups of supramolecular dendritic templates to generate pH/redox dual-responsive theranostic supramolecular PEGylated dendritic systems (TSPDSs). TSPDSs markedly improved the pharmacokinetics and biodistribution of platinum-based drugs, owing to their stable nanostructures and PEGylated shells during the blood circulation. Tumor intracellular environment (low pH value and high glutathione concentration) could trigger the rapid disintegration of TSPDSs due to acid-labile coordination bonds and redox-cleavable disulfide linkages, and then platinum-based drugs were delivered into the nuclei to exert antitumor activity. In vivo antitumor treatments indicated TSPDSs not only provided high antitumor efficiency which was comparable to clinical cisplatin, but also reduced renal toxicity of platinum-based drugs. Moreover, NIR fluorescence of TSPDSs successfully visualized in vitro and in vivo fate of nanoplatforms and disclosed the intracellular platinum delivery and pharmacokinetics. These results confirm tailor-made supramolecular dendritic system with sophisticated nanostructure and excellent performance is a promising candidate as smart theranostic nanoplatforms.

  4. Phosphorylation of the growth factors bFGF, NGF and BDNF: a prerequisite for their biological activity.

    Klumpp, Susanne; Kriha, Dorothee; Bechmann, Gunther; Maassen, Alexander; Maier, Sandra; Pallast, Stefanie; Hoell, Patrick; Krieglstein, Josef

    2006-01-01

    The aim of this work was to test whether growth factors such as basic fibroblast growth factor (bFGF), nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) undergo autophosphorylation and whether this affects their biological activity. Incubation of those growth factors with [gamma-(32)P]ATP resulted in phosphorylation in vitro. The phosphate bond was resistant to alkaline pH, yet acid-labile. Addition of alkaline phosphatase resulted in time and protein dependent dephosphorylation. Concomitantly, alkaline phosphatase abolished the neuroprotective effect of those growth factors upon oxygen and glucose deprivation and upon staurosporine-induced cell death. For those studies, we were using primary cultures of cortical and hippocampal neurons from embryonic and neonatal rats. Incubation of bFGF with non-hydrolyzable ATP-gammaS resulted in phosphorylation and in neuroprotection resistant to alkaline phosphatase. We conclude that bFGF, NGF and BDNF undergo autophosphorylation on site(s) other than serine, threonine, tyrosine and/or ATP-binding, and that this binding of phosphate is essential for neuroprotection in vivo.

  5. Mid-trimester maternal ADAM12 levels differ according to fetal gender in pregnancies complicated by preeclampsia.

    Myers, Jenny E; Thomas, Grégoire; Tuytten, Robin; Van Herrewege, Yven; Djiokep, Raoul O; Roberts, Claire T; Kenny, Louise C; Simpson, Nigel A B; North, Robyn A; Baker, Philip N

    2015-02-01

    An overrepresentation of adverse pregnancy outcomes has been observed in pregnancies associated with a male fetus. We investigated the association between fetal gender and candidate biomarkers for preeclampsia. Proteins were quantified in samples taken at 20 weeks from women recruited to the SCreening fOr Pregnancy Endpoints (SCOPE) study (preeclampsia n = 150; no preeclampsia n = 450). In contrast to placental growth factor, soluble endoglin, and insulin-like growth factor acid labile subunit, levels of metallopeptidase domain 12 (ADAM12) at 20 weeks were dependent on fetal gender in pregnancies complicated by preeclampsia, for male (n = 73) fetuses the multiples of the median (MoM; interquartile range [IQR] 1.1-1.5) was 1.3, whereas for female fetuses (n = 75) MoM was 1.1 (1.0-1.3); P preeclampsia using ADAM12 levels was improved for pregnancies associated with a male fetus (area under receiver-operator curve [AUC] 0.73 [95% confidence interval [CI] 0.67-0.80]) than that of a female fetus (AUC 0.62 [0.55-0.70]); P = .03. The data presented here fit a contemporary hypothesis that there is a difference between the genders in response to an adverse maternal environment and suggest that an alteration in ADAM12 may reflect an altered placental response in pregnancies subsequently complicated by preeclampsia.

  6. Self-Assembly Assisted Fabrication of Dextran-Based Nanohydrogels with Reduction-Cleavable Junctions for Applications as Efficient Drug Delivery Systems

    Wang, Hao; Dai, Tingting; Zhou, Shuyan; Huang, Xiaoxiao; Li, Songying; Sun, Kang; Zhou, Guangdong; Dou, Hongjing

    2017-01-01

    In order to overcome the key challenge in improving both fabrication efficiency and their drug delivery capability of anti-cancer drug delivery systems (ACDDS), here polyacrylic acid (PAA) grafted dextran (Dex) nanohydrogels (NGs) with covalent crosslinked structure bearing redox sensitive disulfide crosslinking junctions (Dex-SS-PAA) were synthesized efficiently through a one-step self-assembly assisted methodology (SAA). The Dex-SS-PAA were subsequently conjugated with doxorubicin through an acid-labile hydrazone bond (Dex-SS-PAA-DOX). The in vitro drug release behavior, anti-cancer effects in vivo, and biosafety of the as-prepared acid- and redox-dual responsive biodegradable NGs were systematically investigated. The results revealed that the Dex-SS-PAA-DOX exhibited pH- and redox-controlled drug release, greatly reduced the toxicity of free DOX, while exhibiting a strong ability to inhibit the growth of MDA-MB-231 tumors. Our study demonstrated that the Dex-SS-PAA-DOX NGs are very promising candidates as ACDDS for anti-cancer therapeutics.

  7. Functional roles and clinical values of insulin-like growth factor-binding protein-5 in different types of cancers

    G(o)k(c)e Güllü; Sevgi Karabulut; Mustafa Akkiprik

    2012-01-01

    Insulin-like growth factor-binding proteins (IGFBPs) are critical regulators of the mitogenic activity of insulin-like growth factors (IGFs).IGFBP5,one of these IGFBPs,has special structural features,including a nuclear transport domain,heparin-binding motif,and IGF/extracellular matrix/acid-labile subunit-binding sites.Furthermore,IGFBP5 has several functional effects on carcinogenesis and even normal cell processes,such as cell growth,death,motility,and tissue remodeling.These biological effects are sometimes related with IGF (IGF-dependent effects) and sometimes not (IGF-independent effects).The functional role of IGFBP5 is most likely determined in a cell-type and tissue-type specific manner but also depends on cell context,especially in terms of the diversity of interacting proteins and the potential for nuclear localization.Clinical findings show that IGFBP5 has the potential to be a useful clinical biomarker for predicting response to therapy and clinical outcome of cancer patients.In this review,we summarize the functional diversity and clinical importance of IGFBP5 in different types of cancers.

  8. Pentaerythrityltetramine scaffolds for solid-phase combinatorial chemistry.

    Virta, Pasi; Leppänen, Marika; Lönnberg, Harri

    2004-03-19

    Straightforward synthesis for two pentaerythrityltetramine precursors, 2,2-bis(azidomethyl)propane-1,3-diamine (1) and 2-[N-(allyloxycarbonyl)aminomethyl]-2-azidomethylpropane-1,3-diamine (2), has been described. Both propane-1,3-diamines have been attached by reductive amination to a solid-supported backbone amide linker derived from 4-(4-formyl-3,5-dimethoxyphenoxy)butyric acid. The presence of the two methoxy substituents on the linker is essential to avoid cross-linking between two linkers. The remaining free primary amino group of the propane-1,3-diamine moiety may then be selectively acylated with an appropriately protected amino acid using conventional N,N-dicyclohexylcarbodiimide/1-hydroxybenzotriazole (DCC/HOBt) activation without any interference by the secondary amino function. The latter group may be subsequently acylated by an anhydride method. Sequential reduction of the azido group and removal of the allyloxycarbonyl protection from 2 allow further coupling of two different amino acids, and hence, this handle may be utilized in construction of branched structures containing four different amino acids or peptides. Solid-supported 1 may, in turn, be used for the synthesis of similar constructs containing two identical branches. It is worth noting that no acid-labile protecting groups are required in this approach, and hence, this dimension may be saved for the cleavage of the linker. The applicability of the scaffolds to library synthesis has been demonstrated by preparation of 11 pentaerythrityl-branched tetra- and octapeptides.

  9. Ohgata, the Single Drosophila Ortholog of Human Cereblon, Regulates Insulin Signaling-dependent Organismic Growth.

    Wakabayashi, Satoru; Sawamura, Naoya; Voelzmann, André; Broemer, Meike; Asahi, Toru; Hoch, Michael

    2016-11-25

    Cereblon (CRBN) is a substrate receptor of the E3 ubiquitin ligase complex that is highly conserved in animals and plants. CRBN proteins have been implicated in various biological processes such as development, metabolism, learning, and memory formation, and their impairment has been linked to autosomal recessive non-syndromic intellectual disability and cancer. Furthermore, human CRBN was identified as the primary target of thalidomide teratogenicity. Data on functional analysis of CRBN family members in vivo, however, are still scarce. Here we identify Ohgata (OHGT), the Drosophila ortholog of CRBN, as a regulator of insulin signaling-mediated growth. Using ohgt mutants that we generated by targeted mutagenesis, we show that its loss results in increased body weight and organ size without changes of the body proportions. We demonstrate that ohgt knockdown in the fat body, an organ analogous to mammalian liver and adipose tissue, phenocopies the growth phenotypes. We further show that overgrowth is due to an elevation of insulin signaling in ohgt mutants and to the down-regulation of inhibitory cofactors of circulating Drosophila insulin-like peptides (DILPs), named acid-labile subunit and imaginal morphogenesis protein-late 2. The two inhibitory proteins were previously shown to be components of a heterotrimeric complex with growth-promoting DILP2 and DILP5. Our study reveals OHGT as a novel regulator of insulin-dependent organismic growth in Drosophila.

  10. Preparation of anatase/rutile mixed-phase titania nanoparticles for dye-sensitized solar cells.

    Hwang, Yong-Kyung; Park, Sung Soo; Lim, Jun-Heok; Won, Yong Sun; Huh, Seong

    2013-03-01

    Acid-labile high surface mesoporous ZnO/Zn(OH)2 composite material is used as a novel hard template for the preparation of mesoporous amorphous TiO2. The template-free amorphous TiO2 material is then thermally crystallized at suitable temperature to control the relative ratio of anatase and rutile phases in a particle. Four different anatase/rutile (AR) mixed-phase TiO2 nanoparticles (AR-3, AR-15, AR-20, and AR-23 denoted for the samples of 3%, 15%, 20%, and 23% rutile phase, respectively) are prepared and characterized by powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM). The coexistence of anatase and rutile phases in a TiO2 nanoparticle is visually confirmed by HRTEM analysis. These mixed-phase TiO2 nanoparticles are examined as candidates for photoelectrodes of dye-sensitized solar cells (DSSCs). The J-V curves and IPCE spectra for the DSSCs prepared from the mixed-phase TiO2 nanoparticles are obtained, and their photovoltaic properties are investigated. The photo-conversion efficiency (eta) indicates the highest value of 5.07% for AR-20. The synergistic effect of coexisting anatase and rutile phases with an optimal ratio in a TiO2 nanoparticle of AR-20 for an efficient interfacial transfer of photo-generated electrons is likely to lead to the highest efficiency among the AR-n samples.

  11. Nanoemulsions as novel oral carriers of stiripentol: insights into the protective effect and absorption enhancement

    Lu R

    2015-07-01

    Full Text Available Rong Lu,1 Shan Liu,1 Qilin Wang,1 Xia Li1,2 1School of Ocean, Shandong University, Weihai, 2School of Pharmaceutical Sciences, Shandong University, Jinan, People’s Republic of China Abstract: Oral administration remains a significant challenge in regards to drugs with serious solubility and stability issues. This article aimed to investigate the suitability of nanoemulsions as oral carriers of stiripentol (STP, an acid-labile drug, for enhancement of stability and bioavailability. STP-loaded nanoemulsions (STP-NEs were prepared by using a solvent-diffusion/ultrasonication technique. STP-NEs were characterized in a variety of ways such as by particle size, entrapment efficiency, in vitro drug release, and transmission electron microscopy. A bioavailability study was performed in rats after oral administration of either STP-NEs, or commercial formulation (Diacomit®. The resultant nanoemulsions were 146.6 nm in particle size with an entrapment efficiency of 99.47%. It was demonstrated that nanoemulsions significantly improved the biochemical stability and bioavailability of STP. The bioavailability of STP-NEs was up to 206.2% relative to Diacomit®. Nanoemulsions fabricated from poly(ethylene glycol monooleate/medium-chain triglycerides exhibited excellent performance in drug stabilization and absorption enhancement. The results suggest that STP-NEs are a promising means to solve the problems associated with stability and solubility of STP. Keywords: stiripentol, nanoemulsions, stability, intestinal permeability, bioavailability

  12. Nanoemulsions as novel oral carriers of stiripentol: insights into the protective effect and absorption enhancement.

    Lu, Rong; Liu, Shan; Wang, Qilin; Li, Xia

    2015-01-01

    Oral administration remains a significant challenge in regards to drugs with serious solubility and stability issues. This article aimed to investigate the suitability of nanoemulsions as oral carriers of stiripentol (STP), an acid-labile drug, for enhancement of stability and bioavailability. STP-loaded nanoemulsions (STP-NEs) were prepared by using a solvent-diffusion/ultrasonication technique. STP-NEs were characterized in a variety of ways such as by particle size, entrapment efficiency, in vitro drug release, and transmission electron microscopy. A bioavailability study was performed in rats after oral administration of either STP-NEs, or commercial formulation (Diacomit). The resultant nanoemulsions were 146.6 nm in particle size with an entrapment efficiency of 99.47%. It was demonstrated that nanoemulsions significantly improved the biochemical stability and bioavailability of STP. The bioavailability of STP-NEs was up to 206.2% relative to Diacomit. Nanoemulsions fabricated from poly(ethylene glycol) monooleate/medium-chain triglycerides exhibited excellent performance in drug stabilization and absorption enhancement. The results suggest that STP-NEs are a promising means to solve the problems associated with stability and solubility of STP.

  13. Structure of the β-l-fucopyranosyl phosphate-containing O-specific polysaccharide of Escherichia coli O84.

    Knirel, Yuriy A; Qian, Chengqian; Senchenkova, Sofya N; Guo, Xi; Shashkov, Alexander S; Chizhov, Alexander O; Perepelov, Andrei V; Liu, Bin

    2016-07-01

    Fine structure of the O-polysaccharide chain of the lipopolysaccharide (O-antigen) defines the serospecificity of bacterial cells, which is the basis for O-serotyping of medically and agriculturally important gram-negative bacteria including Escherichia coli. In order to obtain the O-polysaccharide for structural analysis, the lipopolysaccharide was isolated from cells of E. coli O84a by phenol/water extraction and degraded with mild acid. However, the O-polysaccharide was cleaved at a highly acid-labile β-l-fucopyranosyl phosphate (β-l-Fucp-1-P) linkage to give mainly a pentasaccharide that corresponded to the O-polysaccharide repeat. Therefore, the lipopolysaccharide and the pentasaccharide as well as their O-deacylated derivatives were studied using sugar analysis, NMR spectroscopy, and (for oligosaccharides) ESI HR MS, and the O84-polysaccharide structure was established. The O-polysaccharide is distinguished by the presence of β-l-Fucp-1-P and randomly di-O-acetylated 6-deoxy-d-talose, which are found for the first time in natural carbohydrates. The gene cluster for the O84-antigen biosynthesis was analysed and its content was found to be consistent with the O-polysaccharide structure.

  14. pH and redox-operated nanovalve for size-selective cargo delivery on hollow mesoporous silica spheres.

    Zhu, Xinyun; Wang, Cai-Qi

    2016-10-15

    A pH and redox dual-responsive nanovalve with a long stalk was introduced on the surface of hollow mesoporous silica nanoparticles (HMSs-S1) to achieve cargo size selectivity delivery. The responsive nanovalve was designed by constructing of a stalk/β-cyclodextrins (CDs) supramolecular complex, which is based on an acid-labile acetal group and the host-guest interactions between β-cyclodextrins and ferrocenyl moiety (Fc). With stimulation by different pH and H2O2, Rhodamine 6G showed well-responsive behavior. On account of the long stalks of nanovalve, doxorubicin hydrochloride and 5-fluorouracil with different sized cargos are encapsulated in HMSs-S1 to test its behavior of cargo size-selective delivery. Moreover the HMSs-S2 with a short stalk based on β-CDs/Fc inclusion complex is synthesized to load small sized 5-FU drug as contrast experiment. Compared with HMSs-S2, HMSs-S1 is compatible with larger drug molecules such as Rhodamine 6G (R6G) and doxorubicin hydrochloride (DOX), while small sized 5-fluorouracil (5-FU) is unable to be sealed by the nanovalve. Dual responsiveness and drug size selectivity make mechanized HMSs possess potential applications in drug delivery system.

  15. 生长激素-胰岛素样生长因子轴与肝脏疾病

    黄春; 丁惠国; 汪俊韬

    2001-01-01

    @@生长激素(growth hormone,GH)是在促生长激素释放素及生长抑素的作用下,由腺垂体嗜酸细胞分泌的一种单链多肽蛋白质。肝脏是体内GH作用主要的靶器官,GH调节肝脏合成与分泌胰岛素样生长因子-1(Insulin like growth factor-1,IGF-1)、GH结合蛋白(GHBP)、IGF-1结合蛋白、酸不稳定蛋白亚单位(Acid-labile subunit,ALS)等。因此,将GH-肝脏-IGF-1称为生长激素、胰岛素样生长因子轴,肝脏是这个轴的中枢。我们就GH-IGF轴的生物学功能、与肝脏疾病的关系及生长激素的临床应用做一概述,为慢性肝病的治疗提供新策略。

  16. Divergent behavior of hydrogen sulfide pools and of the sulfur metabolite lanthionine, a novel uremic toxin, in dialysis patients.

    Perna, Alessandra F; Di Nunzio, Annarita; Amoresano, Angela; Pane, Francesca; Fontanarosa, Carolina; Pucci, Piero; Vigorito, Carmela; Cirillo, Giovanni; Zacchia, Miriam; Trepiccione, Francesco; Ingrosso, Diego

    2016-07-01

    Dialysis patients display a high cardiovascular mortality, the causes of which are still not completely explained, but are related to uremic toxicity. Among uremic toxins, homocysteine and cysteine are both substrates of cystathionine β-synthase and cystathionine γ-lyase in hydrogen sulfide biosynthesis, leading to the formation of two sulfur metabolites, lanthionine and homolanthionine, considered stable indirect biomarkers of its production. Hydrogen sulfide is involved in the modulation of multiple pathophysiological responses. In uremia, we have demonstrated low plasma total hydrogen sulfide levels, due to reduced cystathionine γ-lyase expression. Plasma hydrogen sulfide levels were measured in hemodialysis patients and healthy controls with three different techniques in comparison, allowing to discern the different pools of this gas. The protein-bound (the one thought to be the most active) and acid-labile forms are significantly decreased, while homolanthionine, but especially lanthionine, accumulate in the blood of uremic patients. The hemodialysis regimen plays a role in determining sulfur compounds levels, and lanthionine is partially removed by a single dialysis session. Lanthionine inhibits hydrogen sulfide production in cell cultures under conditions comparable to in vivo ones. We therefore propose that lanthionine is a novel uremic toxin. The possible role of high lanthionine as a contributor to the genesis of hyperhomocysteinemia in uremia is discussed.

  17. A pH-responsive drug nanovehicle constructed by reversible attachment of cholesterol to PEGylated poly(l-lysine) via catechol-boronic acid ester formation.

    Yang, Bin; Lv, Yin; Zhu, Jing-Yi; Han, Yun-Tao; Jia, Hui-Zhen; Chen, Wei-Hai; Feng, Jun; Zhang, Xian-Zheng; Zhuo, Ren-Xi

    2014-08-01

    The present work reports the construction of a drug delivery nanovehicle via a pH-sensitive assembly strategy for improved cellular internalization and intracellular drug liberation. Through spontaneous formation of boronate linkage in physiological conditions, phenylboronic acid-modified cholesterol was able to attach onto catechol-pending methoxypoly(ethylene glycol)-block-poly(l-lysine). This comb-type polymer can self-organize into a micellar nanoconstruction that is able to effectively encapsulate poorly water-soluble agents. The blank micelles exhibited negligible in vitro cytotoxicity, yet doxorubicin (DOX)-loaded micelles could effectively induce cell death at a level comparable to free DOX. Owing to the acid-labile feature of the boronate linkage, a reduction in environmental pH from pH 7.4 to 5.0 could trigger the dissociation of the nanoconstruction, which in turn could accelerate the liberation of entrapped drugs. Importantly, the blockage of endosomal acidification in HeLa cells by NH4Cl treatment significantly decreased the nuclear uptake efficiency and cell-killing effect mediated by the DOX-loaded nanoassembly, suggesting that acid-triggered destruction of the nanoconstruction is of significant importance in enhanced drug efficacy. Moreover, confocal fluorescence microscopy and flow cytometry assay revealed the effective internalization of the nanoassemblies, and their cellular uptake exhibited a cholesterol dose-dependent profile, indicating the contribution of introduced cholesterol functionality to the transmembrane process of the nanoassembly.

  18. Urea, glycolic acid, and glycerol in an organic residue produced by ultraviolet irradiation of interstellar/pre-cometary ice analogs.

    Nuevo, Michel; Bredehöft, Jan Hendrik; Meierhenrich, Uwe J; d'Hendecourt, Louis; Thiemann, Wolfram H-P

    2010-03-01

    More than 50 stable organic molecules have been detected in the interstellar medium (ISM), from ground-based and onboard-satellite astronomical observations, in the gas and solid phases. Some of these organics may be prebiotic compounds that were delivered to early Earth by comets and meteorites and may have triggered the first chemical reactions involved in the origin of life. Ultraviolet irradiation of ices simulating photoprocesses of cold solid matter in astrophysical environments have shown that photochemistry can lead to the formation of amino acids and related compounds. In this work, we experimentally searched for other organic molecules of prebiotic interest, namely, oxidized acid labile compounds. In a setup that simulates conditions relevant to the ISM and Solar System icy bodies such as comets, a condensed CH(3)OH:NH(3) = 1:1 ice mixture was UV irradiated at approximately 80 K. The molecular constituents of the nonvolatile organic residue that remained at room temperature were separated by capillary gas chromatography and identified by mass spectrometry. Urea, glycolic acid, and glycerol were detected in this residue, as well as hydroxyacetamide, glycerolic acid, and glycerol amide. These organics are interesting target molecules to be searched for in space. Finally, tentative mechanisms of formation for these compounds under interstellar/pre-cometary conditions are proposed.

  19. Molecular fingerprinting of carbohydrate structure phenotypes of three porifera proteoglycan-like glyconectins.

    Guerardel, Yann; Czeszak, Xavier; Sumanovski, Lazar T; Karamanos, Yannis; Popescu, Octavian; Strecker, Gerard; Misevic, Gradimir N

    2004-04-01

    Glyconectins (GNs) represent a new class of proteoglycan-like cell adhesion and recognition molecules found in several Porifera species. Physico-chemical properties of GN carbohydrate moieties, such as size, composition, and resistance to most glycosaminoglycan-degrading enzymes, distinguish them from any other type of known glycoproteins. The molecular mechanism of GN-mediated self/non-self discrimination function is based on highly species-specific and Ca(2+)-dependent GN to GN associations that approach the selectivity of the evolutionarily advanced immunoglobulin superfamily. Carbohydrates of glyconectins 1, 2, and 3 are essential for species-specific auto-aggregation properties in three respective Porifera species. To obtain a structural insight into the molecular mechanisms, we performed carbohydrate structural analyses of glyconectins isolated from the three sponge model systems, Microciona prolifera (GN1), Halichondria panicea (GN2), and Cliona celata (GN3). The glycan content of all three GNs ranged between 40 and 60% of their total mass. Our approach using sequential and selective chemical degradation of GN glycans and subsequent mass spectrometric and NMR analyses revealed that each glyconectin presents novel and highly species-specific carbohydrate sequences. All three GNs include distinct acid-resistant and acid-labile carbohydrate domains, the latter composed of novel repetitive units. We have sequenced four short sulfated and one pyruvilated unit in GN1, eight larger and branched pyruvilated oligosaccharides in GN2, which represent a heterogeneous but related family of structures, and four sulfated units in GN3.

  20. Activation of adriamycin by the pH-dependent formaldehyde-releasing prodrug hexamethylenetetramine.

    Swift, Lonnie P; Cutts, Suzanne M; Rephaeli, Ada; Nudelman, Abraham; Phillips, Don R

    2003-02-01

    Previous studies have shown that Adriamycin can react with formaldehyde to yield an activated form of Adriamycin that can further react with DNA to yield Adriamycin-DNA adducts. Because hexamethylenetetramine (HMTA) is known to hydrolyze under cellular conditions and release six molecules of formaldehyde in a pH-dependent manner, we examined this clinical agent for its potential as a formaldehyde-releasing prodrug for the activation of Adriamycin. In IMR-32 neuroblastoma cells in culture, increasing levels of HMTA resulted in enhanced levels of Adriamycin-DNA adducts. These adducts were formed in a pH-dependent manner, with 4-fold more detected at pH 6.5 compared with pH 7.4, consistent with the known acid lability of HMTA. The resulting drug-DNA lesion was shown to be cytotoxic, with combined Adriamycin and prodrug treatment resulting in a 3-fold lower IC(50) value compared with that of Adriamycin alone. Given the acidic nature of solid tumors and the preferential release of formaldehyde from HMTA in acidic environments, HMTA therefore has some potential for localized activation of Adriamycin in solid tumors.

  1. Polysomnographic sleep, growth hormone insulin-like growth factor-I axis, leptin, and weight loss

    Rasmussen, Michael; Wildschiødtz, Gordon; Juul, Anders

    2008-01-01

    Short sleep appears to be strongly associated with obesity and altered metabolic function, and sleep and growth hormone (GH) secretion seems interlinked. In obesity, both the GH-insulin-like-growth-factor-I (GH-IGF-I) axis and sleep have been reported to be abnormal, however, no studies have...... investigated sleep in relation to the GH-IGF-I axis and weight loss in obese subjects. In this study polygraphic sleep recordings, 24-h GH release, 24-h leptin levels, free-IGF-I, total-IGF-I, IGF-binding protein-3 (IGFBP-3), acid-labile subunit (ALS), cortisol and insulin sensitivity were determined in six...... severely obese subjects (BMI: 41+/-1 kg/m(2), 32+/-2 years of age), cross-sectional at baseline, and longitudinal after a dramatically diet-induced weight loss (36+/-7 kg). Ten age- and gender-matched nonobese subjects served as controls. Sleep duration (360+/-17 vs. 448+/-15 min/night; P

  2. Advances in the study of tumor pH-responsive polymeric micelles for Cancer drug targeting delivery%肿瘤pH响应的聚合物胶束用于肿瘤药物靶向输送的研究进展

    许金霞; 唐建斌; 赵鲁杭; 申有青

    2009-01-01

    This review presents the state of the an of pH-responsive polymeric micelles for cancer drug delivery.Solid tumors have a weakly acidic extracellular pH(pH<7),and cancer cells have even more acidic pH in endosomes and lysosomes(pH 4-6).The pH-gradients in tumor can be explored for tumor targeting and drug release in cancer drug delivery by applying pH-responsive polymeric micelles.The pH-responsive polymeric micelles consist of a corona and a core,and are made of amphiphilic copolymers,in which there are pH-responsive polymeric blocks.Two types of pH-responsive polymers-protonizable polymers and acid-labile polymers have been mainly used to make pH-responsive micelles for drug delivery.The protonizable polymers are polybases or polyacids,and their water-soluble/insoluble or charge states undergo changes with the protonation or deprotonation stimulated by external acidity,while the acid-labile polymers change their physical properties by chemical reaction stimulated by the acidity.Polymeric micelles whose core or coronas respond to the tumor extracellular acidity can be explored for triggering the fast release of the carried drug,activating the targeting group and accelerating the endocytosis of drug-loaded polymeric micelles,and those whose core or coronas respond to the tumor lysosomal acidity can be used for facilitating their escape from the lysosomes and targeting the nucleus.Various in vivo and in vitro experiments demonstrated that pH-responsive polymeric micelles are effective for cellular targeting,internalization,fast drug release and nuclear localization,and hence enhancing the therapeutic efficacy and reducing the side effect of cancer chemical therapy.%本文综述了肿瘤pH响应的聚合物胶柬(pH-responsive polymeric micelles)靶向输送抗癌药物的研究进展.肿瘤组织的细胞问质呈弱酸性(pH<7),而肿瘤细胞内的内涌体和溶酶体具有更强的酸性(pH 4~6).pH响应的聚合物胶束的内核或外壳在肿瘤酸性pH下

  3. Cell penetrating peptide-based polyplexes shelled with polysaccharide to improve stability and gene transfection

    Li, Wenyu; Liu, Yajie; Du, Jianwei; Ren, Kefeng; Wang, Youxiang

    2015-04-01

    Cell-penetrating peptides (CPP) have been widely developed as a strategy to enhance cell penetrating ability and transfection. In this work, octa-arginine modified dextran gene vector with pH-sensitivity was developed via host-guest interactions. α-Cyclodextrin was modified with octa-arginine (CDR), which had excellent cell penetrating ability. Dextran was selected as a backbone and modified with azobenzene as guest units by acid-labile imine bonds (Az-I-Dex). The supramolecular polymer CDR/Az-I-Dex with high a C/A molar ratio (molar ratio of CD on CDR to Az on Az-I-Dex) was unfavorable for DNA condensation. The dextran shell of CDR/Az-I-Dex/DNA polyplexes improved the stability under physiological conditions. However, once treated with acetate buffer (pH 5.4) for 3 h, large aggregates formed rapidly due to the cleavage of the dextran shell. As expected, the vector had cell viability of 80% even when the CDR concentration increased to 100 μg mL-1. Moreover, due to the effective cellular uptake efficiency, CDR/Az-I-Dex/DNA polyplexes had 6-300 times higher transfection efficiency than CDR/DNA polyplexes. It was even higher than high molecular weight PLL-based polyplexes of HEK293 T cells. Importantly, chloroquine as an endosomal escape agent could not improve the transfection of CDR/Az-I-Dex/DNA polyplexes, which indicated that the CDR/Az-I-Dex supramolecular polymer had its own ability for endosomal escape. These results suggested that the CPP-based polyplexes shelled with polysaccharide can be promising non-viral gene delivery carriers.Cell-penetrating peptides (CPP) have been widely developed as a strategy to enhance cell penetrating ability and transfection. In this work, octa-arginine modified dextran gene vector with pH-sensitivity was developed via host-guest interactions. α-Cyclodextrin was modified with octa-arginine (CDR), which had excellent cell penetrating ability. Dextran was selected as a backbone and modified with azobenzene as guest units by acid-labile

  4. cvhA Gene of Streptomyces hygroscopicus 10-22 Encodes a Negative Regulator for Mycelia Development

    Heng-An WANG; Lei QIN; Ping LU; Zhi-Xuan PANG; Zi-Xin DENG; Guo-Ping ZHAO

    2006-01-01

    A five-gene cluster cvhABCDE was identified from Streptomyces hygroscopicus 10-22. As the first gene of this cluster, cvhA encoded a putative sensor histidine kinase with a predicted sensor domain consisting of two trans-membrane segments at the N-terminus and a conserved HATPase_c domain at the Cterminus. The C-terminus polypeptide of CvhA expressed in Escherichia coli was purified and shown to be autophosphorylated with [γ-32p]ATP in vitro. The phosphoryl group was acid-labile and basic-stable, which supported histidine as the phosphorylation residue. No obvious difference of mycelia development was observed between the null mutant of cvhA generated by targeted gene replacement and the wild-type parental strain 10-22 grown on solid soya flour medium with 2%-8% glucose or sucrose, but the cvhA mutant could form much more abundant aerial mycelia and spores than the wild-type strain on solid soya flour medium supplemented with 6%-8% mannitol, 6%-8% sorbitol, 4%-6% mannose, or 4%-6% fructose. This phenotype was complemented by the cloned wild-type cvhA gene, and no difference was observed for growth curves of the cvhA mutant and the wild strain in liquid minimal medium with the tested sugars at a concentration of 4%, 6% and 8%. We thus propose that CvhA is likely a sensor histidine kinase and negatively regulates the morphological differentiation in a sugar-dependent manner in S. hygroscopicus 10-22.

  5. AS1411 aptamer and folic acid functionalized pH-responsive ATRP fabricated pPEGMA-PCL-pPEGMA polymeric nanoparticles for targeted drug delivery in cancer therapy.

    Lale, Shantanu V; R G, Aswathy; Aravind, Athulya; Kumar, D Sakthi; Koul, Veena

    2014-05-12

    Nonspecificity and cardiotoxicity are the primary limitations of current doxorubicin chemotherapy. To minimize side effects and to enhance bioavailability of doxorubicin to cancer cells, a dual-targeted pH-sensitive biocompatible polymeric nanosystem was designed and developed. An ATRP-based biodegradable triblock copolymer, poly(poly(ethylene glycol) methacrylate)-poly(caprolactone)-poly(poly(ethylene glycol) methacrylate) (pPEGMA-PCL-pPEGMA), conjugated with doxorubicin via an acid-labile hydrazone bond was synthesized and characterized. Dual targeting was achieved by attaching folic acid and the AS1411 aptamer through EDC-NHS coupling. Nanoparticles of the functionalized triblock copolymer were prepared using the nanoprecipitation method, resulting in an average particle size of ∼140 nm. The biocompatibility of the nanoparticles was evaluated using MTT cytotoxicity assays, blood compatibility studies, and protein adsorption studies. In vitro drug release studies showed a higher cumulative doxorubicin release at pH 5.0 (∼70%) compared to pH 7.4 (∼25%) owing to the presence of the acid-sensitive hydrazone linkage. Dual targeting with folate and the AS1411 aptamer increased the cancer-targeting efficiency of the nanoparticles, resulting in enhanced cellular uptake (10- and 100-fold increase in uptake compared to single-targeted NPs and non-targeted NPs, respectively) and a higher payload of doxorubicin in epithelial cancer cell lines (MCF-7 and PANC-1), with subsequent higher apoptosis, whereas a normal (noncancerous) cell line (L929) was spared from the adverse effects of doxorubicin. The results indicate that the dual-targeted pH-sensitive biocompatible polymeric nanosystem can act as a potential drug delivery vehicle against various epithelial cancers such as those of the breast, ovary, pancreas, lung, and others.

  6. Structure of an Odorant-Vinding Protein form the Mosquito Aedes aegypti Suggests a Binding Pocket Covered by a pH-Sensitive

    N Leite; R Krogh; W Xu; Y Ishida; J Iulek; W Leal; G Oliva

    2011-12-31

    The yellow fever mosquito, Aedes aegypti, is the primary vector for the viruses that cause yellow fever, mostly in tropical regions of Africa and in parts of South America, and human dengue, which infects 100 million people yearly in the tropics and subtropics. A better understanding of the structural biology of olfactory proteins may pave the way for the development of environmentally-friendly mosquito attractants and repellents, which may ultimately contribute to reduction of mosquito biting and disease transmission. Previously, we isolated and cloned a major, female-enriched odorant-binding protein (OBP) from the yellow fever mosquito, AaegOBP1, which was later inadvertently renamed AaegOBP39. We prepared recombinant samples of AaegOBP1 by using an expression system that allows proper formation of disulfide bridges and generates functional OBPs, which are indistinguishable from native OBPs. We crystallized AaegOBP1 and determined its three-dimensional structure at 1.85 {angstrom} resolution by molecular replacement based on the structure of the malaria mosquito OBP, AgamOBP1, the only mosquito OBP structure known to date. The structure of AaegOBP1 (= AaegOBP39) shares the common fold of insect OBPs with six {alpha}-helices knitted by three disulfide bonds. A long molecule of polyethylene glycol (PEG) was built into the electron-density maps identified in a long tunnel formed by a crystallographic dimer of AaegOBP1. Circular dichroism analysis indicated that delipidated AaegOBP1 undergoes a pH-dependent conformational change, which may lead to release of odorant at low pH (as in the environment in the vicinity of odorant receptors). A C-terminal loop covers the binding cavity and this 'lid' may be opened by disruption of an array of acid-labile hydrogen bonds thus explaining reduced or no binding affinity at low pH.

  7. Purification and some properties of component B of the 4-chlorophenylacetate 3,4-dioxygenase from Pseudomonas species strain CBS 3.

    Schweizer, D; Markus, A; Seez, M; Ruf, H H; Lingens, F

    1987-07-05

    4-Chlorophenylacetate 3,4-dioxygenase system from Pseudomonas sp. CBS 3 consists of two protein components, a red-brown iron-sulfur protein (component A) which functions as dioxygenase and an orange-colored reductase (component B). Component B was purified by a five-step procedure. Criterion of purity was sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which also showed that the protein consists of one polypeptide species with a molecular weight of 35,000. With gel chromatography on Sephadex G-100 also, a molecular weight of 35,000 was found for the native enzyme, suggesting a monomeric structure for the reductase enzyme. The isoelectric point was determined as pH 4.8. The visible absorption spectrum of the homogeneous protein exhibits maxima at 336, 394, and 458 nm. One mol of FMN, 2.1 mol of iron, and 1.7 mol of acid-labile sulfide were found in one mol of component B. The EPR-spectrum of the reduced form of the enzyme (with NADH) showed two types of signals. The signal at g values of 2.03, 1.94, and 1.90 was assigned to an iron-sulfur cluster of the [2Fe-2S]-type. The properties of the other signal type at g = 2.004 are characteristic of flavosemiquinone radical which does not show coupling to an other paramagnetic center. The apparent Km values for 2,6-dichlorophenolindophenol, cytochrome c, and NADH were calculated from Lineweaver-Burk plots as 6.3, 2.3, and 32 microM, respectively. Inhibitors of the reductase are metal-chelating reagents and sulfhydryl-inhibiting compounds. Component B reduces several redox compounds: 2,6-dichlorophenolindophenol, potassium hexacyanoferrat III, cytochrome c, methylene blue, and nitro blue tetrazolium.

  8. Review article: immediate-release proton-pump inhibitor therapy--potential advantages.

    Howden, C W

    2005-12-01

    The absorption of most oral proton-pump inhibitors is delayed by the enteric coating required to protect the acid-labile proton-pump inhibitor from degradation in the stomach and, as a result, antisecretory effect is also delayed. This article provides an overview of the pharmacokinetics and pharmacodynamics of a new immediate-release omeprazole [(IR-OME) Zegerid power for oral suspension; Santarus Inc., San Diego, CA, USA] and its potential advantages over delayed-release proton-pump inhibitors. Immediate-release omeprazole has a higher mean peak plasma omeprazole concentration (C(max)) and a significantly shorter mean time to reach C(max) (t(max)) than delayed-release omeprazole. Immediate-release omeprazole 40 mg has a prolonged antisecretory effect with median intragastric pH above 4.0 for 18.6 h/day at steady-state, after 7 days of once daily dosing. The sodium bicarbonate in immediate-release omeprazole protects the uncoated omeprazole from degradation by gastric acid. The accelerated antisecretory action of immediate-release omeprazole compared with delayed-release omeprazole may be due to the activation of proton pumps by the rapid neutralization of intragastric acid by the sodium bicarbonate. The faster onset of action seen with immediate-release omeprazole is not achieved by using an antacid with a delayed-release proton-pump inhibitor, because administering antacids with conventional delayed-release proton-pump inhibitors does not significantly enhance absorption of the proton-pump inhibitor. In conclusion, immediate-release omeprazole is associated with rapid absorption of omeprazole and rapid onset of antisecretory effect, without compromising the duration of acid suppression.

  9. Biodegradable polyglycerols with randomly distributed ketal groups as multi-functional drug delivery systems.

    Shenoi, Rajesh A; Lai, Benjamin F L; Imran ul-haq, Muhammad; Brooks, Donald E; Kizhakkedathu, Jayachandran N

    2013-08-01

    Biodegradable multi-functional polymeric nanostructures that undergo controlled degradation in response to physiological cues are important in numerous biomedical applications including drug delivery, bio-conjugation and tissue engineering. In this paper, we report the development of a new class of water soluble multi-functional branched biodegradable polymer with high molecular weight and biocompatibility which demonstrates good correlation of in vivo biodegradation and in vitro hydrolysis. Main chain degradable hyperbranched polyglycerols (HPG) (20-100 kDa) were synthesized by the introduction of acid labile groups within the polymer structure by an anionic ring opening copolymerization of glycidol with ketal-containing epoxide monomers with different ketal structures. The water soluble biodegradable HPGs with randomly distributed ketal groups (RBHPGs) showed controlled degradation profiles in vitro depending on the pH of solution, temperature and the structure of incorporated ketal groups, and resulted in non-toxic degradation products. NMR studies demonstrated the branched nature of RBHPGs which is correlating with their smaller hydrodynamic radii. The RBHPGs and their degradation products exhibited excellent blood compatibility and tissue compatibility based on various analyses methods, independent of their molecular weight and ketal group structure. When administered intravenously in mice, tritium labeled RBHPG of molecular weight 100 kDa with dimethyl ketal group showed a circulation half life of 2.7 ± 0.3 h, correlating well with the in vitro polymer degradation half life (4.3 h) and changes in the molecular weight profile during the degradation (as measured by gel permeation chromatography) in buffer conditions at 37 °C. The RBHPG degraded into low molecular weight fragments that were cleared from circulation rapidly. The biodistribution and excretion studies demonstrated that RBHPG exhibited significantly lower tissue accumulation and enhanced urinary

  10. Optimised extraction of heterocyclic aromatic amines from blood using hollow fibre membrane liquid-phase microextraction and triple quadrupole mass spectrometry.

    Cooper, Kevin M; Jankhaikhot, Natcha; Cuskelly, Geraldine

    2014-09-05

    Heterocyclic aromatic amines (HCA) are carcinogenic mutagens formed during cooking of proteinaceous foods, particularly meat. To assist in the ongoing search for biomarkers of HCA exposure in blood, a method is described for the extraction from human plasma of the most abundant HCAs: 2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) (and its isomer 7,8-DiMeIQx), using hollow fibre membrane liquid-phase microextraction. This technique employs 2.5cm lengths of porous polypropylene fibres impregnated with organic solvent to facilitate simultaneous extraction from an alkaline aqueous sample into a low volume acidic acceptor phase. This low cost protocol is extensively optimised for fibre length, extraction time, sample pH and volume. Detection is by UPLC-MS/MS using positive mode electrospray ionisation with a 3.4min runtime, with optimum peak shape, sensitivity and baseline separation being achieved at pH 9.5. To our knowledge this is the first description of HCA chromatography under alkaline conditions. Application of fixed ion ratio tolerances for confirmation of analyte identity is discussed. Assay precision is between 4.5 and 8.8% while lower limits of detection between 2 and 5pg/mL are below the concentrations postulated for acid-labile HCA-protein adducts in blood.

  11. Molecular cloaking of H2A.Z on mortal DNA chromosomes during nonrandom segregation.

    Huh, Yang Hoon; Sherley, James L

    2011-10-01

    Although nonrandom sister chromatid segregation is a singular property of distributed stem cells (DSCs) that are responsible for renewing and repairing mature vertebrate tissues, both its cellular function and its molecular mechanism remain unknown. This situation persists in part because of the lack of facile methods for detecting and quantifying nonrandom segregating cells and for identifying chromosomes with immortal DNA strands, the cellular molecules that signify nonrandom segregation. During nonrandom segregation, at each mitosis, asymmetrically self-renewing DSCs continuously cosegregate to themselves the set of chromosomes that contain immortal DNA strands, which are the oldest DNA strands. Here, we report the discovery of a molecular asymmetry between segregating sets of immortal chromosomes and opposed mortal chromosomes (i.e., containing the younger set of DNA template strands) that constitutes a new convenient biomarker for detection of cells undergoing nonrandom segregation and direct delineation of chromosomes that bear immortal DNA strands. In both cells engineered with DSC-specific properties and ex vivo-expanded mouse hair follicle stem cells, the histone H2A variant H2A.Z shows specific immunodetection on immortal DNA chromosomes. Cell fixation analyses indicate that H2A.Z is present on mortal chromosomes as well but is cloaked from immunodetection, and the cloaking entity is acid labile. The H2A.Z chromosomal asymmetry produced by molecular cloaking provides a first direct assay for nonrandom segregation and for chromosomes with immortal DNA strands. It also seems likely to manifest an important aspect of the underlying mechanism(s) responsible for nonrandom sister chromatid segregation in DSCs.

  12. Genetic factors associated with small for gestational age birth and the use of human growth hormone in treating the disorder.

    Saenger, Paul; Reiter, Edward

    2012-05-15

    The term small for gestational age (SGA) refers to infants whose birth weights and/or lengths are at least two standard deviation (SD) units less than the mean for gestational age. This condition affects approximately 3%-10% of newborns. Causes for SGA birth include environmental factors, placental factors such as abnormal uteroplacental blood flow, and inherited genetic mutations. In the past two decades, an enhanced understanding of genetics has identified several potential causes for SGA. These include mutations that affect the growth hormone (GH)/insulin-like growth factor (IGF)-1 axis, including mutations in the IGF-1 gene and acid-labile subunit (ALS) deficiency. In addition, select polymorphisms observed in patients with SGA include those involved in genes associated with obesity, type 2 diabetes, hypertension, ischemic heart disease and deletion of exon 3 growth hormone receptor (d3-GHR) polymorphism. Uniparental disomy (UPD) and imprinting effects may also underlie some of the phenotypes observed in SGA individuals. The variety of genetic mutations associated with SGA births helps explain the diversity of phenotype characteristics, such as impaired motor or mental development, present in individuals with this disorder. Predicting the effectiveness of recombinant human GH (hGH) therapy for each type of mutation remains challenging. Factors affecting response to hGH therapy include the dose and method of hGH administration as well as the age of initiation of hGH therapy. This article reviews the results of these studies and summarizes the success of hGH therapy in treating this difficult and genetically heterogenous disorder.

  13. Genetic factors associated with small for gestational age birth and the use of human growth hormone in treating the disorder

    Saenger Paul

    2012-05-01

    Full Text Available Abstract The term small for gestational age (SGA refers to infants whose birth weights and/or lengths are at least two standard deviation (SD units less than the mean for gestational age. This condition affects approximately 3%–10% of newborns. Causes for SGA birth include environmental factors, placental factors such as abnormal uteroplacental blood flow, and inherited genetic mutations. In the past two decades, an enhanced understanding of genetics has identified several potential causes for SGA. These include mutations that affect the growth hormone (GH/insulin-like growth factor (IGF-1 axis, including mutations in the IGF-1 gene and acid-labile subunit (ALS deficiency. In addition, select polymorphisms observed in patients with SGA include those involved in genes associated with obesity, type 2 diabetes, hypertension, ischemic heart disease and deletion of exon 3 growth hormone receptor (d3-GHR polymorphism. Uniparental disomy (UPD and imprinting effects may also underlie some of the phenotypes observed in SGA individuals. The variety of genetic mutations associated with SGA births helps explain the diversity of phenotype characteristics, such as impaired motor or mental development, present in individuals with this disorder. Predicting the effectiveness of recombinant human GH (hGH therapy for each type of mutation remains challenging. Factors affecting response to hGH therapy include the dose and method of hGH administration as well as the age of initiation of hGH therapy. This article reviews the results of these studies and summarizes the success of hGH therapy in treating this difficult and genetically heterogenous disorder.

  14. Comparison of alternative buffers for use with a new live oral cholera vaccine, Peru-15, in outpatient volunteers.

    Sack, D A; Shimko, J; Sack, R B; Gomes, J G; MacLeod, K; O'Sullivan, D; Spriggs, D

    1997-06-01

    During development of Peru-15, a new live oral vaccine for cholera, the role of buffer needed to be evaluated. Generally, oral bacterial vaccines are acid labile and need to be administered by using a formulation which protects them from gastric acid. We compared three different buffers for use with Peru-15, including a standard bicarbonate-ascorbic acid buffer, Alka-Seltzer, and a new electrolyte-rice buffer, CeraVacx. Saline served as the control. Thirty-nine healthy adult volunteers received Peru-15 (10(8) CFU) with one of the three buffers or saline in a double-masked study. The volunteers were monitored for symptoms for 7 days after the dose, serum was tested for antibody responses by vibriocidal antibody and immunoglobulin G antitoxin enzyme-linked immunosorbent assays, and stool samples were tested for excretion of the vaccine strain. Side effects were minimal in all groups. All 30 volunteers who took Peru-15 with a buffer showed significant rises in vibriocidal antibody titer. The magnitude of the rises was higher in the CeraVacx group than in the other two buffer groups. Four of nine volunteers who took the vaccine with saline also showed increased titers, but they were lower than those in any of the three buffer groups. Excretion of the vaccine strain was similar in the buffer groups, but excretion was not associated with the magnitude of the vibriocidal responses. Excretion of Peru-15 was not detected in the saline group. We conclude that buffer does amplify the serological response to Peru-15 and that CeraVacx may provide benefits not provided by other buffers.

  15. Stepwise-activable multifunctional peptide-guided prodrug micelles for cancerous cells intracellular drug release

    Zhang, Jing; Li, Mengfei; Yuan, Zhefan; Wu, Dan; Chen, Jia-da; Feng, Jie

    2016-10-01

    A novel type of stepwise-activable multifunctional peptide-guided prodrug micelles (MPPM) was fabricated for cancerous cells intracellular drug release. Deca-lysine sequence (K10), a type of cell-penetrating peptide, was synthesized and terminated with azido-glycine. Then a new kind of molecule, alkyne modified doxorubicin (DOX) connecting through disulfide bond (DOX-SS-alkyne), was synthesized. After coupling via Cu-catalyzed azide-alkyne cycloaddition (CuAAC) click chemistry reaction, reduction-sensitive peptide-guided prodrug was obtained. Due to the amphiphilic property of the prodrug, it can assemble to form micelles. To prevent the nanocarriers from unspecific cellular uptake, the prodrug micelles were subsequently modified with 2,3-dimethyl maleic anhydride to obtain MPPM with a negatively charged outer shell. In vitro studies showed that MPPM could be shielded from cells under psychological environment. However, when arriving at mild acidic tumor site, the cell-penetrating capacity of MPPM would be activated by charge reversal of the micelles via hydrolysis of acid-labile β-carboxylic amides and regeneration of K10, which enabled efficient internalization of MPPM by tumor cells as well as following glutathione- and protease-induced drug release inside the cancerous cells. Furthermore, since the guide peptide sequences can be accurately designed and synthesized, it can be easily changed for various functions, such as targeting peptide, apoptotic peptide, even aptamers, only need to be terminated with azido-glycine. This method can be used as a template for reduction-sensitive peptide-guided prodrug for cancer therapy.

  16. Development of an Acid-Resistant Salmonella Typhi Ty21a Attenuated Vector For Improved Oral Vaccine Delivery

    Feuille, Catherine M.; Starke, Carly Elizabeth C.; Bhagwat, Arvind A.; Stibitz, Scott; Kopecko, Dennis J.

    2016-01-01

    The licensed oral, live-attenuated bacterial vaccine for typhoid fever, Salmonella enterica serovar Typhi strain Ty21a, has also been utilized as a vaccine delivery platform for expression of diverse foreign antigens that stimulate protection against shigellosis, anthrax, plague, or human papilloma virus. However, Ty21a is acid-labile and, for effective oral immunization, stomach acidity has to be either neutralized with buffer or by-passed with Ty21a in an enteric-coated capsule (ECC). Several studies have shown that efficacy is reduced when Ty21a is administered in an ECC versus as a buffered liquid formulation, the former limiting exposure to GI tract lymphoid tissues. However, the ECC was selected as a more practical delivery format for both packaging/shipping and vaccine administration ease. We have sought to increase Ty21a acid-resistance to allow for removal from the ECC and immune enhancement. To improve Ty21a acid-resistance, glutamate-dependent acid resistance genes (GAD; responsible for Shigella spp. survival at very low pH) were cloned on a multi-copy plasmid (pGad) under a controllable arabinose-inducible promoter. pGad enhanced acid survival of Ty21a by 5 logs after 3 hours at pH 2.5, when cells were pre-grown in arabinose and under conditions that promote an acid-tolerance response (ATR). For genetically 100% stable expression, we inserted the gad genes into the Ty21a chromosome, using a method that allowed for subsequent removal of a selectable antibiotic resistance marker. Further, both bacterial growth curves and survival assays in cultured human monocytes/macrophages suggest that neither the genetic methods employed nor the resulting acid-resistance conferred by expression of the Gad proteins in Ty21a had any effect on the existing attenuation of this vaccine strain. PMID:27673328

  17. N-nitrosation of medicinal drugs catalysed by bacteria from human saliva and gastro-intestinal tract, including Helicobacter pylori.

    Ziebarth, D; Spiegelhalder, B; Bartsch, H

    1997-02-01

    Micro-organisms commonly present in human saliva and three DSM strains (Helicobacter pylori, Campylobacter jejuni and Neisseria cinerea), which can be isolated from the human gastro-intestinal tract, were assayed in vitro for their capacity to catalyse N-nitrosation of a series of medicinal drugs and other compounds. Following incubation at pH 7.2 in the presence of nitrate (or nitrite) for up to 24 (48) h, the yield of N-nitroso compounds (NOC) was quantified by HPLC equipped with a post-column derivatization device, allowing the sensitive detection of acid-labile and acid-stable NOC. Eleven out of the 23 test compounds underwent bacteria-catalysed nitrosation by salivary bacteria, the yield of the respective nitrosation products varying 800-fold. 4-(Methylamino)antipyrine exhibited the highest rate of nitrosation, followed by dichlofenac > metamizole > piperazine > five other drugs, whilst L-proline and L-thioproline had the lowest nitrosation rate. Ten drugs including aminophenazone, cimetidine and nicotine, did not inhibit bacterial growth, allowing transitory nitrite to be formed, but no N-nitroso derivatives were detected. Three drugs inhibited the proliferation of bacteria and neither nitrite nor any NOC were formed. Using metamizole as an easily nitrosatable precursor, two strains, Campylobacter jejuni and Helicobacter pylori, were shown to catalyse nitrosation in the presence of nitrite at pH 7.2. As compared to Neisseria cinerea used as a nitrosation-proficient control strain, H. pylori was 30-100 times less effective, whilst C. jejuni had intermediary activity. The results of our sensitive nitrosation assay further confirm that bacteria isolated from human sources, possessing nitrate reductase and/or nitrosating enzymes such as cytochrome cd1-nitrite reductase (Calmels et al., Carcinogenesis, 17, 533-536, 1996), can contribute to intragastric nitrosamine formation in the anacidic stomach when nitrosatable precursors from exogenous and endogenous sources

  18. Analysis of Bacterial Lipooligosaccharides by MALDI-TOF MS with Traveling Wave Ion Mobility

    Phillips, Nancy J.; John, Constance M.; Jarvis, Gary A.

    2016-07-01

    Lipooligosaccharides (LOS) are major microbial virulence factors displayed on the outer membrane of rough-type Gram-negative bacteria. These amphipathic glycolipids are comprised of two domains, a core oligosaccharide linked to a lipid A moiety. Isolated LOS samples are generally heterogeneous mixtures of glycoforms, with structural variability in both domains. Traditionally, the oligosaccharide and lipid A components of LOS have been analyzed separately following mild acid hydrolysis, although important acid-labile moieties can be cleaved. Recently, an improved method was introduced for analysis of intact LOS by MALDI-TOF MS using a thin layer matrix composed of 2,4,6-trihydroxyacetophenone (THAP) and nitrocellulose. In addition to molecular ions, the spectra show in-source "prompt" fragments arising from regiospecific cleavage between the lipid A and oligosaccharide domains. Here, we demonstrate the use of traveling wave ion mobility spectrometry (TWIMS) for IMS-MS and IMS-MS/MS analyses of intact LOS from Neisseria spp. ionized by MALDI. Using IMS, the singly charged prompt fragments for the oligosaccharide and lipid A domains of LOS were readily separated into resolved ion plumes, permitting the extraction of specific subspectra, which led to increased confidence in assigning compositions and improved detection of less abundant ions. Moreover, IMS separation of precursor ions prior to collision-induced dissociation (CID) generated time-aligned, clean MS/MS spectra devoid of fragments from interfering species. Incorporating IMS into the profiling of intact LOS by MALDI-TOF MS exploits the unique domain structure of the molecule and offers a new means of extracting more detailed information from the analysis.

  19. Analysis of Bacterial Lipooligosaccharides by MALDI-TOF MS with Traveling Wave Ion Mobility.

    Phillips, Nancy J; John, Constance M; Jarvis, Gary A

    2016-07-01

    Lipooligosaccharides (LOS) are major microbial virulence factors displayed on the outer membrane of rough-type Gram-negative bacteria. These amphipathic glycolipids are comprised of two domains, a core oligosaccharide linked to a lipid A moiety. Isolated LOS samples are generally heterogeneous mixtures of glycoforms, with structural variability in both domains. Traditionally, the oligosaccharide and lipid A components of LOS have been analyzed separately following mild acid hydrolysis, although important acid-labile moieties can be cleaved. Recently, an improved method was introduced for analysis of intact LOS by MALDI-TOF MS using a thin layer matrix composed of 2,4,6-trihydroxyacetophenone (THAP) and nitrocellulose. In addition to molecular ions, the spectra show in-source "prompt" fragments arising from regiospecific cleavage between the lipid A and oligosaccharide domains. Here, we demonstrate the use of traveling wave ion mobility spectrometry (TWIMS) for IMS-MS and IMS-MS/MS analyses of intact LOS from Neisseria spp. ionized by MALDI. Using IMS, the singly charged prompt fragments for the oligosaccharide and lipid A domains of LOS were readily separated into resolved ion plumes, permitting the extraction of specific subspectra, which led to increased confidence in assigning compositions and improved detection of less abundant ions. Moreover, IMS separation of precursor ions prior to collision-induced dissociation (CID) generated time-aligned, clean MS/MS spectra devoid of fragments from interfering species. Incorporating IMS into the profiling of intact LOS by MALDI-TOF MS exploits the unique domain structure of the molecule and offers a new means of extracting more detailed information from the analysis. Graphical Abstract ᅟ.

  20. Unbound (bioavailable IGF1 enhances somatic growth

    Sebastien Elis

    2011-09-01

    Understanding insulin-like growth factor-1 (IGF1 biology is of particular importance because, apart from its role in mediating growth, it plays key roles in cellular transformation, organ regeneration, immune function, development of the musculoskeletal system and aging. IGF1 bioactivity is modulated by its binding to IGF-binding proteins (IGFBPs and the acid labile subunit (ALS, which are present in serum and tissues. To determine whether IGF1 binding to IGFBPs is necessary to facilitate normal growth and development, we used a gene-targeting approach and generated two novel knock-in mouse models of mutated IGF1, in which the native Igf1 gene was replaced by Des-Igf1 (KID mice or R3-Igf1 (KIR mice. The KID and KIR mutant proteins have reduced affinity for the IGFBPs, and therefore present as unbound IGF1, or ‘free IGF1’. We found that both KID and KIR mice have reduced serum IGF1 levels and a concomitant increase in serum growth hormone levels. Ternary complex formation of IGF1 with the IGFBPs and the ALS was markedly reduced in sera from KID and KIR mice compared with wild type. Both mutant mice showed increased body weight, body and bone lengths, and relative lean mass. We found selective organomegaly of the spleen, kidneys and uterus, enhanced mammary gland complexity, and increased skeletal acquisition. The KID and KIR models show unequivocally that IGF1-complex formation with the IGFBPs is fundamental for establishing normal body and organ size, and that uncontrolled IGF bioactivity could lead to pathological conditions.

  1. Disulfiram/copper-disulfiram Damages Multiple Protein Degradation and Turnover Pathways and Cytotoxicity is Enhanced by Metformin in Oesophageal Squamous Cell Carcinoma Cell Lines.

    Jivan, Rupal; Damelin, Leonard Howard; Birkhead, Monica; Rousseau, Amanda Louise; Veale, Robin Bruce; Mavri-Damelin, Demetra

    2015-10-01

    Disulfiram (DSF), used since the 1950s in the treatment of alcoholism, is reductively activated to diethyldithiocarbamate and both compounds are thiol-reactive and readily complex copper. More recently DSF and copper-DSF (Cu-DSF) have been found to exhibit potent anticancer activity. We have previously shown that the anti-diabetic drug metformin is anti-proliferative and induces an intracellular reducing environment in oesophageal squamous cell carcinoma (OSCC) cell lines. Based on these observations, we investigated the effects of Cu-DSF and DSF, with and without metformin, in this present study. We found that Cu-DSF and DSF caused considerable cytotoxicity across a panel of OSCC cells, and metformin significantly enhanced the effects of DSF. Elevated copper transport contributes to DSF and metformin-DSF-induced cytotoxicity since the cell-impermeable copper chelator, bathocuproinedisulfonic acid, partially reversed the cytotoxic effects of these drugs, and interestingly, metformin-treated OSCC cells contained higher intracellular copper levels. Furthermore, DSF may target cancer cells preferentially due to their high dependence on protein degradation/turnover pathways, and we found that metformin further enhances the role of DSF as a proteasome inhibitor. We hypothesized that the lysosome could be an additional, novel, target of DSF. Indeed, this acid-labile compound decreased lysosomal acidification, and DSF-metformin co-treatment interfered with the progression of autophagy in these cells. In summary, this is the first such report identifying the lysosome as a target of DSF and based on the considerable cytotoxic effects of DSF either alone or in the presence of metformin, in vitro, and we propose these as novel potential chemotherapeutic approaches for OSCC.

  2. Drug release mechanisms of compressed lipid implants.

    Kreye, F; Siepmann, F; Siepmann, J

    2011-02-14

    The aim of this study was to elucidate the mass transport mechanisms controlling drug release from compressed lipid implants. The latter steadily gain in importance as parenteral controlled release dosage forms, especially for acid-labile drugs. A variety of lipid powders were blended with theophylline and propranolol hydrochloride as sparingly and freely water-soluble model drugs. Cylindrical implants were prepared by direct compression and thoroughly characterized before and after exposure to phosphate buffer pH 7.4. Based on the experimental results, an appropriate mathematical theory was identified in order to quantitatively describe the resulting drug release patterns. Importantly, broad release spectra and release periods ranging from 1 d to several weeks could easily be achieved by varying the type of lipid, irrespective of the type of drug. Interestingly, diffusion with constant diffusivities was found to be the dominant mass transport mechanism, if the amount of water within the implant was sufficient to dissolve all of the drug. In these cases an analytical solution of Fick's second law could successfully describe the experimentally measured theophylline and propranolol hydrochloride release profiles, even if varying formulation and processing parameters, e.g. the type of lipid, initial drug loading, drug particles size as well as compression force and time. However, based on the available data it was not possible to distinguish between drug diffusion control and water diffusion control. The obtained new knowledge can nevertheless significantly help facilitating the optimization of this type of advanced drug delivery systems, in particular if long release periods are targeted, which require time consuming experimental trials.

  3. Structure of an odorant-binding protein from the mosquito Aedes aegypti suggests a binding pocket covered by a pH-sensitive "Lid".

    Ney Ribeiro Leite

    Full Text Available BACKGROUND: The yellow fever mosquito, Aedes aegypti, is the primary vector for the viruses that cause yellow fever, mostly in tropical regions of Africa and in parts of South America, and human dengue, which infects 100 million people yearly in the tropics and subtropics. A better understanding of the structural biology of olfactory proteins may pave the way for the development of environmentally-friendly mosquito attractants and repellents, which may ultimately contribute to reduction of mosquito biting and disease transmission. METHODOLOGY: Previously, we isolated and cloned a major, female-enriched odorant-binding protein (OBP from the yellow fever mosquito, AaegOBP1, which was later inadvertently renamed AaegOBP39. We prepared recombinant samples of AaegOBP1 by using an expression system that allows proper formation of disulfide bridges and generates functional OBPs, which are indistinguishable from native OBPs. We crystallized AaegOBP1 and determined its three-dimensional structure at 1.85 A resolution by molecular replacement based on the structure of the malaria mosquito OBP, AgamOBP1, the only mosquito OBP structure known to date. CONCLUSION: The structure of AaegOBP1 ( = AaegOBP39 shares the common fold of insect OBPs with six alpha-helices knitted by three disulfide bonds. A long molecule of polyethylene glycol (PEG was built into the electron-density maps identified in a long tunnel formed by a crystallographic dimer of AaegOBP1. Circular dichroism analysis indicated that delipidated AaegOBP1 undergoes a pH-dependent conformational change, which may lead to release of odorant at low pH (as in the environment in the vicinity of odorant receptors. A C-terminal loop covers the binding cavity and this "lid" may be opened by disruption of an array of acid-labile hydrogen bonds thus explaining reduced or no binding affinity at low pH.

  4. A one-pot procedure for the preparation of N-9-fluorenylmethyloxycarbonyl-α-amino diazoketones from α-amino acids.

    Siciliano, Carlo; De Marco, Rosaria; Guidi, Ludovica Evelin; Spinella, Mariagiovanna; Liguori, Angelo

    2012-12-07

    The study describes a new "one-pot" route to the synthesis of N-9-fluorenylmethyloxycarbonyl (Fmoc) α-amino diazoketones. The procedure was tested on a series of commercially available free or side-chain protected α-amino acids employed as precursors. The conversion into the title compounds was achieved by masking and activating the α-amino acids with a single reagent, namely, 9-fluorenylmethyl chloroformate (Fmoc-Cl). The resulting N-protected mixed anhydrides were reacted with diazomethane to lead to the α-amino diazoketones, which were isolated by flash column chromatography in very good to excellent overall yields. The versatility of the procedure was verified on lipophilic α-amino acids and further demonstrated by the preparation of N-Fmoc-α-amino diazoketones also from α-amino acids containing side-chain masking groups, which are orthogonal to the Fmoc one. The results confirmed that tert-butyloxycarbonyl (Boc), tert-butyl ((t)Bu), and 2,2,4,6,7-pentamethyldihydrobenzofuran-5-sulfonyl (Pbf), three acid-labile protecting groups mostly adopted in the solution and solid-phase peptide synthesis, are compatible to the adopted reaction conditions. In all cases, the formation of the corresponding C-methyl ester of the starting amino acid was not observed. Moreover, the proposed method respects the chirality of the starting α-amino acids. No racemization occurred when the procedure was applied to the synthesis of the respective N-Fmoc-protected α-amino diazoketones from L-isoleucine and L-threonine and to the preparation of a diastereomeric pair of N-Fmoc-protected dipeptidyl diazoketones.

  5. In-situ nanochemistry for optoelectronics

    Kim, Won Jin

    This thesis describes recent results on simple methods to arrange nanosize objects such as semiconductor nanocrystals, noble metal nanoparticles, and upconversion nanophosphors by means of top-down processes. Specific focus is directed towards approaches to produce predefined patterns of various nanostructure materials using optical lithography for direct writing of films for optoelectronic and electronic devices. To obtain photo-patternability, the nanostructure materials [for example semiconductor nanocrystals (CdSe, CdTe, PbSe), metallic nanoparticles (Ag), upconversion nanophosphors (Er3+/Yb 3+ or Tm3+/Yb3+ co-doped NaYF4 ), and transparent conducting oxide nanoparticles (ITO, ZnO)] were functionalized by incorporation of the functional ligand t-butoxycarbonyl (t-BOC) which has an acid-labile moiety. The t-BOC group undergoes a cleavage, when subjected to UV irradiation in the presence of a photo acid generator (PAG) to releases isobutene and carbon dioxide. Depending on the need of the application, either the exposed regions (negative pattern) or the non-exposed regions (positive pattern) could be developed from the exposed films by appropriate solvent selection. The photo exposed regions of the film are rendered hydrophilic due to the degradation of the t-BOC, the un-exposed regions remain hydrophobic. This solubility change in the QDs is the basis of their patternablity. The un-exposed regions can be removed to obtain the negative pattern by washing with hydrophobic solvents, whereas the exposed regions can be selectively removed to obtain positive pattern by washing with hydrophilic solvents. This change in the surface chemistry results in the ability to photo-pattern the various nanostructure materials where desired for a number of optoelectronic device geometries. We demonstrate that the ultimate resolution (linewidth and spacing) of this technique is below submicron. Details on technological aspects concerning nanoparticle patterning as well as practical

  6. Ligand and counterion control of Ag(I) architectures: assembly of a {Ag8} ring cluster mediated by hydrophobic and Ag...Ag interactions.

    Fielden, John; Long, De-liang; Slawin, Alexandra M Z; Kögerler, Paul; Cronin, Leroy

    2007-10-29

    A strategy combining ligand design and counterion variation has been used to investigate the assembly of silver(I) complexes. As a result, dinuclear, octanuclear, and polymeric silver(I) species have been synthesized by complexation of the rigid aliphatic amino ligands cis-3,5-diamino-trans-hydroxycyclohexane (DAHC), cis-3,5-diamino-trans-methoxycyclohexane (DAMC), and cis-3,5-diamino-trans-tert-butyldimethylsilylanyloxycyclohexane (DATC) with silver(I) triflate, nitrate, and perchlorate. The compositions of these aggregates, established by X-ray crystallography and elemental analysis, are [{Ag(DAHC)}2](CF3SO3)2 (1), [{Ag(DAMC)}2](CF3SO3)2 (2), [{Ag(DAMC)}2](NO3)2 (3), [{Ag(DATC)}6{Ag(DAHC)}2](NO3)8 (4), and [{Ag(DATC}n](NO3)n (5), where the DAHC present in 4 is formed by in situ hydrolysis of the acid labile silyl ether group. The type of aggregate formed depends both upon the noncoordinating O-substituent of the ligand and the (also noncoordinating) counterion, with the normal preference of the ligand topology for forming Ag2L2 structures being broken by introduction of the bulky, lipophilic O-tert-butyldimethylsilyl (TBDMS) group. Of particular note is the octanuclear silver ring structure 4, which is isolated only when both the O-TBDMS group and the nitrate counteranion are present and is formed from four Ag2L2 dimers connected by Ag...Ag and hydrogen-bonding interactions. Diffusion rate measurement of this {Ag8} complex by 1H NMR (DOSY) indicates dissociation in CD3OD and CD3CN, showing that this supramolecular ring structure is formed upon crystallization, and establishing a qualitative limit to the strength of Ag...Ag interactions in solution. When solutions of the {Ag8} cluster in methanol are kept for several days though, a new UV-vis absorption is observed at around 430 nm, consistent with the formation of silver nanoparticles.

  7. Temporal variability of reactive iron over the Gulf of Alaska shelf

    Aguilar-Islas, Ana M.; Séguret, Marie J. M.; Rember, Robert; Buck, Kristen N.; Proctor, Peter; Mordy, Calvin W.; Kachel, Nancy B.

    2016-10-01

    The Gulf of Alaska (GoA) shelf is a highly productive regime bordering the nitrate-rich, iron (Fe)-limited waters of the central GoA. The exchange between nitrate-limited, Fe-replete coastal waters and nitrate-rich, Fe-deplete offshore waters, amplified by mesoscale eddies, is key to the productivity of the region. Previous summer field studies have observed the partitioning of Fe in the coastal GoA as being heavily dominated by the particulate phase due to the high suspended particulate loads carried by glacial rivers into these coastal waters. Here we present new physico-chemical iron data and nutrient data from the continental shelf of the GoA during spring and late summer 2011. The late summer data along the Seward Line showed variable surface dissolved iron (DFe) concentrations (0.052 nM offshore to 4.87 nM inshore), within the range of previous observations. Relative to available surface nitrate, DFe was in excess (at Fe:C=50 μmol:mol) inshore, and deficient (at Fe:C=20 μmol:mol) offshore. Summer surface total dissolvable iron (TDFe, acidified unfiltered samples) was dominated by the acid-labile particulate fraction over the shelf (with a median contribution of only 3% by DFe), supporting previously observed Fe partitioning in the GoA. In contrast, our spring data from southeast GoA showed TDFe differently partitioned, with surface DFe (0.28-4.91 nM) accounting on average for a much higher fraction (~25%) of the TDFe pool. Spring surface DFe was insufficient relative to available nitrate over much of the surveyed region (at Fe:C=50 μmol:mol). Organic Fe-binding ligand data reveal excess concentrations of ligands in both spring and summer, indicating incomplete titration by Fe. Excess concentrations of an especially strong-binding ligand class in spring surface waters may reflect in-situ ligand production. Due to anomalous spring conditions in 2011, river flow and phytoplankton biomass during our spring sampling were lower than the expected May average. We

  8. An alternative and expedient synthesis of radioiodinated 4-iodophenylalanine

    Vaidyanathan, Ganesan, E-mail: ganesan.v@duke.edu [Department of Radiology, Box 3808, Duke University Medical Center, Durham, NC 27710 (United States); McDougald, Darryl; Grasfeder, Linda; Zalutsky, Michael R.; Chin, Bennett [Department of Radiology, Box 3808, Duke University Medical Center, Durham, NC 27710 (United States)

    2011-10-15

    Radiolabeled amino acids have been used extensively in oncology both as diagnostic and therapeutic agents. In our pursuit to develop radiopharmaceuticals to target breast cancer, we were interested in determining the uptake of radioiodinated 4-iodophenylalanine, among other labeled amino acids, in breast cancer cells. In this work, we have developed an alternative method for the synthesis of this agent. The novel tin precursor, (S)-tert-butyl 2-(tert-butoxycarbonylamino)-3-(4-(tributylstannyl)phenyl)propanoate (3) was synthesized from the known, corresponding iodo derivative. Initially, the labeled 4-iodophenylalanine was synthesized from the above tin precursor in two steps with radiochemical yields of 91.6{+-}2.7% and 83.7{+-}1.7% (n=5), for the radioiodination (first) and deprotection (second) step, respectively. Subsequently, it was synthesized in a single step with an average radiochemical yield of 94.8{+-}3.4% (n=5). After incubation with MCF-7 breast cancer cells for 60 min, an uptake of up to 49.0{+-}0.7% of the input dose was seen; in comparison, the uptake of [{sup 14}C]phenylalanine under the same conditions was 55.9{+-}0.5%. Furthermore, the uptake of both tracers was inhibited to a similar degree in a concentration-dependent manner by both unlabeled phenylalanine and 4-iodophenylalanine. With [{sup 14}C]phenylalanine as the tracer, IC{sub 50} values of 1.45 and 2.50 mM were obtained for Phe and I-Phe, respectively, and these values for [{sup 125}I]I-Phe inhibition were 1.3 and 1.0 mM. In conclusion, an improved and convenient method for the synthesis of no-carrier-added 4-[{sup *}I]phenylalanine was developed and the radiotracer prepared by this route demonstrated an amino acid transporter-mediated uptake in MCF-7 breast cancer cells in vitro that was comparable to that of [{sup 14}C]phenylalanine. - Highlights: > A new method to synthesize radioiodinated 4-iodophenylalanine. > Acid-labile protecting groups containing tin precursor. > Efficient removal

  9. Doxorubicin-loaded aromatic imine-contained amphiphilic branched star polymer micelles: synthesis, self-assembly, and drug delivery

    Qiu L

    2015-05-01

    Full Text Available Liang Qiu, Chun-Yan Hong, Cai-Yuan Pan Chinese Academy of Sciences Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui, People’s Republic of China Abstract: Redox- and pH-sensitive branched star polymers (BSPs, BP(DMAEMA-co-MAEBA-co-DTDMA(PMAIGPns, have been successively prepared by two steps of reversible addition–fragmentation chain transfer (RAFT polymerization. The first step is RAFT polymerization of 2-(N,N-dimethylaminoethylmethacrylate (DMAEMA and p-(methacryloxyethoxybenzaldehyde (MAEBA in the presence of divinyl monomer, 2,2'-dithiodiethoxyl dimethacrylate (DTDMA. The resultant branched polymers were used as a macro-RAFT agent in the subsequent RAFT polymerization. After hydrolysis of the BSPs to form BP(DMAEMA-co-MAEBA-co-DTDMA(PMAGPns (BSP-H, the anticancer drug doxorubicin (DOX was covalently linked to branched polymer chains by reaction of primary amine of DOX and aldehyde groups in the polymer chains. Their compositions, structures, molecular weights, and molecular weight distributions were respectively characterized by nuclear magnetic resonance spectra and gel permeation chromatography measurements. The DOX-loaded micelles were fabricated by self-assembly of DOX-containing BSPs in water, which were characterized by transmission electron microscopy and dynamic light scattering. Aromatic imine linkage is stable in neutral water, but is acid-labile; controlled release of DOX from the BSP-H-DOX micelles was realized at pH values of 5 and 6, and at higher acidic solution, fast release of DOX was observed. In vitro cytotoxicity experiment results revealed low cytotoxicity of the BSPs and release of DOX from micelles in HepG2 and HeLa cells. Confocal laser fluorescence microscopy observations showed that DOX-loaded micelles have specific interaction with HepG2 cells. Thus, this type of BSP micelle is an efficient drug delivery system

  10. The membrane-bound quinohemoprotein alcohol dehydrogenase from Gluconacetobacter diazotrophicus PAL5 carries a [2Fe-2S] cluster.

    Gómez-Manzo, S; Solano-Peralta, A; Saucedo-Vázquez, J P; Escamilla-Marván, J E; Kroneck, P M H; Sosa-Torres, M E

    2010-03-23

    Gluconacetobacter diazotrophicus stands out among the acetic acid bacteria as it fixes dinitrogen and is a true endophyte. It has a set of constitutive enzymes to oxidize ethanol and acetaldehyde which is upregulated during N(2)-dependent growth. The membrane-bound alcohol dehydrogenase (ADH) is a heterodimer (subunit I approximately 72 kDa, subunit II approximately 44 kDa) and constitutes an important component of this organism. ADH of Ga. diazotrophicus is a typical quinohemoprotein with one pyrroloquinoline quinone (PQQ) and four c-type cytochromes. For the first time, a [2Fe-2S] cluster has been identified by EPR spectroscopy in this type of enzyme. This finding is supported by quantitative chemical analysis, revealing 5.90 +/- 0.15 Fe and 2.06 +/- 0.10 acid-labile sulfurs per ADH heterodimer. The X-band EPR spectrum of ADH (as isolated in the presence of dioxygen, 20 K) showed three broad resonances at g 2.007, 1.941, and 1.920 (g(av) 1.956), as well as an intense narrow line centered at g = 2.0034. The latter signal, which was still detected at 100 K, was attributed to the PQQ semiquinone radical (PQQ(sq)). The broad resonances observed at lower temperature were assigned to the [2Fe-2S] cluster in the one-electron reduced state. The oxidation-reduction potentials E(m) (pH 6.0 vs SHE) of the four c-type cytochromes were estimated to E(m1) = -64 (+/-2) mV, E(m2) = -8 (+/-2) mV, E(m3) = +185 (+/-15) mV, and E(m4) = +210 (+/-10) mV (spectroelectrochemistry), E(mFeS) = -250 (+/-5) mV for the [2Fe-2S] cluster, and E(mPQQ) = -210 (+/-5) mV for the PQQ/PQQH(2) couple (EPR spectroscopy). We propose a model for the membrane-bound ADH of Ga. diazotrophicus showing hypothetical intra- and intermolecular electron pathways. Subunit I binds the PQQ cofactor, the [2Fe-2S] cluster, and one c-type cytochrome. Subunit II harbors three c-type cytochromes, thus providing an efficient electron transfer route to quinones located in the cytoplasmic membrane.

  11. Proton pump inhibitor-associated pneumonia:Not a breath of fresh air after all?

    Alexander; L; Fohl; Randolph; E; Regal

    2011-01-01

    Over the past two decades,proton pump inhibitors (PPIs)have emerged as highly effective and relatively safe agents for the treatment of a variety of gastrointestinal disorders.Unfortunately,this desirable pharmacological profile has also contributed to superfluous and widespread use in both the inpatient and outpatient settings.While generally well-tolerated,research published over the last decade has associated these agents with increased risks of Clostridium difficile disease, fractures likely due to calcium malabsorption and both community-acquired(CAP)and hospital-acquired pneumonias(HAP).The mechanism behind PPI-associated pneumonia may be multifactorial,but is thought to stem from compromising the stomach’s"acid mantle"against gastric colonization of acid-labile pathogenic bacteria which then may be aspirated.A secondary postulate is that PPIs,through their inhibition of extra-gastric H+/K+ATPase enzymes,may reduce the acidity of the upper aerodigestive tract,thus resulting in increased bacterial colonization of the larynx,esophagus and lungs.To date,several retrospective case control studies have been published looking at the association between PPI use and CAP.Some studies found a temporal relationship between PPI exposure and the incidence of pneumonia,but only two could define a dose-response re-lationship.Furthermore,other studies found an inverse correlation between duration of PPI use and risk of CAP. In terms of HAP,we reviewed two retrospective cohort studies and one prospective study.One retrospective study in a medical ICU found no increased association of HAP in PPI-exposed patients compared to no acid-lowering therapy,while the other in cardiothoracic surgery patients showed a markedly increased risk compared to those receiving H2RAs.The one prospective study in ICU patients showed an increased risk of HAP with PPIs, but not with H2RAs.In conclusion,the current literature shows a slight trend toward an association between PPI use and pneumonia

  12. Rapid, Efficient and Versatile Strategies for Functionally Sophisticated Polymers and Nanoparticles: Degradable Polyphosphoesters and Anisotropic Distribution of Chemical Functionalities

    Zhang, Shiyi

    conjugate by densely attaching the polyphosphoester block with azide-functionalized Paclitaxel by azide-alkyne Huisgen cycloaddition. This Paclitaxel drug conjugate provides a powerful platform for combinational cancer therapy and bioimaging due to its ultra-high Paclitaxel loading (> 65 wt%), high water solubility (>6.2 mg/mL for PTX) and easy functionalization. Another polyphosphoester-based nanoparticle system has been developed by a programmable process for the rapid and facile preparation of a family of nanoparticles with different surface charges and functionalities. The non-ionic, anionic, cationic and zwitterionic nanoparticles with hydrodynamic diameters between 13 nm to 21 nm and great size uniformity could be rapidly prepared from small molecules in 6 h or 2 days. The anionic and zwitterionic nanoparticles were designed to load silver ions to treat pulmonary infections, while the cationic nanoparticles are being applied to regulate lung injuries by serving as a degradable iNOS inhibitor conjugates. In addition, a direct synthesis of acid-labile polyphosphoramidate by organobase-catalyzed ring-opening polymerization and an improved two-step preparation of polyphosphoester ionomer by acid-assisted cleavage of phosphoramidate bonds on polyphosphoramidate were developed. Polyphosphoramidate and polyphosphoester ionomers may be applied to many applications, due to their unique chemical and physical properties.

  13. lnteracciones de la respuesta del eje somatotrófco en la amenorrea hipotalámica funcional relacionada con la desnutrición The activity of the somatotrophic function in Functional Hypothalamic Amenorrhea (FHA related to undernourishmant

    L Fiszlejder

    2011-03-01

    ólisis que aporta glucosa. No obstante, el aumento de los ácidos grasos libres y eventualmente la aparición de cuerpos cetónicos cuando la alimentación es muy restringida, sugieren la presencia de acidosis metabólica. Este estadio clínico implica un aumento del riesgo cardiovascular y la posibilidad de muerte prematura o súbita, una eventualidad latente en las pacientes con AHF y desnutridas. El autor declara no poseer conflictos de intereses.The activity of the somatotropic function in Functional Hypothalamic Amenorrhea (FHA is increased at the central level, and paradoxically, the peripheral hormonal behaviour, intermediate metabolism and several clinical aspects may be similar to those observed in somatotropic axis deficiency. Baseline and daily GH secretion levels are high, but its pulsatile profile is irregular. This results in resistance to GH, i.e., downregulation of hormone receptors, which, together with the decrease in GH binding protein (GHBP, impair GH ability to stimulate the synthesis of IGF-I, IGFBP-3 and the acid-labile subunit in the liver. This causes a decrease in the availability of free IGF-I in tissues. In addition, IGFBP-1 and IGF-BP2 significantly increase. Even if these peptides are regulated by GH, their inverse correlation with insulin activity (which is decreased in these patients and the low protein diet, respectively, appear to be more important factors. The increase in the serum levels of these peptides also contributes to the decrease in free IGF-I. Alterations in secretory patterns lead to a decrease in leptin concentration (an adipokine and to an increase in Ghrelin, which, in turn, facilitates GH secretion and has a remarkable incidence in intermediate metabolism in these undernourished patients. These hormonal changes can be interpreted as a mechanism of homeostatic adaptation tending to preserve availability of energetic nutrients. Thus, there is an initial predominance of lypolisis followed by proteolysis at muscle level. If