Bioactivity of Sodium Free Fluoride Containing Glasses and Glass-Ceramics

PubMed Central

Chen, Xiaojing; Chen, Xiaohui; Brauer, Delia S.; Wilson, Rory M.; Hill, Robert G.; Karpukhina, Natalia

2014-01-01

The bioactivity of a series of fluoride-containing sodium-free calcium and strontium phosphosilicate glasses has been tested in vitro. Glasses with high fluoride content were partially crystallised to apatite and other fluoride-containing phases. The bioactivity study was carried out in Tris and SBF buffers, and apatite formation was monitored by XRD, FTIR and solid state NMR. Ion release in solutions has been measured using ICP-OES and fluoride-ion selective electrode. The results show that glasses with low amounts of fluoride that were initially amorphous degraded rapidly in Tris buffer and formed apatite as early as 3 h after immersion. The apatite was identified as fluorapatite by 19F MAS-NMR after 6 h of immersion. Glass degradation and apatite formation was significantly slower in SBF solution compared to Tris. On immersion of the partially crystallised glasses, the fraction of apatite increased at 3 h compared to the amount of apatite prior to the treatment. Thus, partial crystallisation of the glasses has not affected bioactivity significantly. Fast dissolution of the amorphous phase was also indicated. There was no difference in kinetics between Tris and SBF studies when the glass was partially crystallised to apatite before immersion. Two different mechanisms of apatite formation for amorphous or partially crystallised glasses are discussed. PMID:28788139

Determination of Novel Strategies for Hastening Corneal Wound Healing and Reducing Tissue Inflammation

DTIC Science & Technology

2011-10-01

blocking buffer, 5% fat -free milk in 0.1% Tris-buffered solution/Tween-20, for 1 hour at room temperature and then probed overnight at 5°C with...and blotting onto Immun-Blot PVDF membrane (Bio-Rad, Hercules, CA). Membranes were blocked with blocking buffer, 5% fat -free milk in 1x PBS buffer...distribution unlimited 13. SUPPLEMENTARY NOTES The aim of this study is to uncover novel transient receptor potential protein vanilloid-1 (TRPV1

Experimental Germ Tube Induction in Candida albicans: An Evaluation of the Effect of Sodium Bicarbonate on Morphogenesis and Comparison with Pooled Human Serum.

PubMed

Matare, Tapiwa; Nziramasanga, Pasipanodya; Gwanzura, Lovemore; Robertson, Valerie

2017-01-01

The potential of NaHCO 3 versus human serum to induce germ tube formation in Candida albicans was investigated. A total of 100 isolates were obtained from oral swabs of patients presenting with thrush. Approval for the study was granted by the Joint Research Ethics Committee (JREC/23/08). Confirmed C. albicans isolates by routine methods were tested for germ tube induction using 5 different concentrations of Tris-maleate buffered NaHCO 3 and Tris-maleate buffer control. Standard control strains included were C. albicans (ATCC 10231) and C. krusei (ATCC 6258). Microculture was done in 20  μ L inoculums on microscope slides for 3 hours at 37°C. The rate of germ tube formation at 10-minute intervals was determined on 100 isolates using the optimum 20 mM Tris-maleate buffered NaHCO 3 concentration. Parallel germ tube formation using human serum was done in test tubes. The optimum concentration of NaHCO 3 in Tris-maleate buffer for germ tube induction was 20 mM for 67% of isolates. Only 21% of isolates formed germ tubes in Tris-maleate buffer control. There was no significant difference in induction between human serum and Tris-maleate buffered NaHCO 3 . Tris-maleate buffered NaHCO 3 induced germ tube formation in C. albicans isolates at rates similar to human serum.

Effect of Pressure-Induced Changes in the Ionization Equilibria of Buffers on Inactivation of Escherichia coli and Staphylococcus aureus by High Hydrostatic Pressure

PubMed Central

Gayán, Elisa; Condón, Santiago; Álvarez, Ignacio; Nabakabaya, Maria

2013-01-01

Survival rates of Escherichia coli and Staphylococcus aureus after high-pressure treatment in buffers that had large or small reaction volumes (ΔV°), and which therefore underwent large or small changes in pH under pressure, were compared. At a low buffer concentration of 0.005 M, survival was, as expected, better in MOPS (morpholinepropanesulfonic acid), HEPES, and Tris, whose ΔV° values are approximately 5.0 to 7.0 cm3 mol−1, than in phosphate or dimethyl glutarate (DMG), whose ΔV° values are about −25 cm3 mol−1. However, at a concentration of 0.1 M, survival was unexpectedly better in phosphate and DMG than in MOPS, HEPES, or Tris. This was because the baroprotective effect of phosphate and DMG increased much more rapidly with increasing concentration than it did with MOPS, HEPES, or Tris. Further comparisons of survival in solutions of salts expected to cause large electrostriction effects (Na2SO4 and CaCl2) and those causing lower electrostriction (NaCl and KCl) were made. The salts with divalent ions were protective at much lower concentrations than salts with monovalent ions. Buffers and salts both protected against transient membrane disruption in E. coli, but the molar concentrations necessary for membrane protection were much lower for phosphate and Na2SO4 than for HEPES and NaCl. Possible protective mechanisms discussed include effects of electrolytes on water compressibility and kosmotropic and specific ion effects. The results of this systematic study will be of considerable practical significance in studies of pressure inactivation of microbes under defined conditions but also raise important fundamental questions regarding the mechanisms of baroprotection by ionic solutes. PMID:23624471

Mass Spectrometry Based Mechanistic Insights into Formation of Tris Conjugates: Implications on Protein Biopharmaceutics

NASA Astrophysics Data System (ADS)

Kabadi, Pradeep G.; Sankaran, Praveen Kallamvalliillam; Palanivelu, Dinesh V.; Adhikary, Laxmi; Khedkar, Anand; Chatterjee, Amarnath

2016-10-01

We present here extensive mass spectrometric studies on the formation of a Tris conjugate with a therapeutic monoclonal antibody. The results not only demonstrate the reactive nature of the Tris molecule but also the sequence and reaction conditions that trigger this reactivity. The results corroborate the fact that proteins are, in general, prone to conjugation and/or adduct formation reactions and any modification due to this essentially leads to formation of impurities in a protein sample. Further, the results demonstrate that the conjugation reaction happens via a succinimide intermediate and has sequence specificity. Additionally, the data presented in this study also shows that the Tris formation is produced in-solution and is not an in-source phenomenon. We believe that the facts given here will open further avenues on exploration of Tris as a conjugating agent as well as ensure that the use of Tris or any ionic buffer in the process of producing a biopharmaceutical drug is monitored closely for the presence of such conjugate formation.

Electrogenerated chemiluminescence of tris(2,2' bipyridine)ruthenium(II) using common biological buffers as co-reactant, pH buffer and supporting electrolyte.

PubMed

Kebede, Noah; Francis, Paul S; Barbante, Gregory J; Hogan, Conor F

2015-11-07

A series of aliphatic tertiary amines (HEPES, POPSO, EPPS and BIS-TRIS) commonly used to buffer the pH in biological experiments, were examined as alternative, non-toxic co-reactants for the electrogenerated chemiluminescence (ECL) of tris(2,2'-bipyridine)ruthenium(ii) ([Ru(bpy)3](2+)). These were found to be very attractive as "multi-tasking" reagents, serving not only as co-reactants, but also fulfiling the roles of pH buffer and supporting electrolyte within an aqueous environment; thus significantly simplifying the overall ECL analysis. Sub-nanomolar detection limits were obtained for [Ru(bpy)3](2+) in the presence of BIS-TRIS, making this species an valuable option for co-reactant ECL-based bioanalytical applications.

Measurement of superoxide dismutase-like activity in peel and pulp of apple from Anshan acres

NASA Astrophysics Data System (ADS)

Zhao, Lijuan

2018-04-01

Pyrogallol autoxidation method was used for measurement of SOD-like activity. They are 259.56 u/g and 148.78 u/g in peel and pulp of apple from Anshan acres. The proper-conditions for this measurement was determined through experiment as following: detection wavelength of spectrophotometer 325nm, buffer system Tris-HAc, concentration of Tris-HAc solution 50 mmoL and pH8.2. The inhibition rate of SOD-L again pyrogallol antioxidation are 92% and 90% in peel and pulp of apple.

Fish Viruses: Buffers and Methods for Plaquing Eight Agents Under Normal Atmosphere

PubMed Central

Wolf, Ken; Quimby, M. C.

1973-01-01

A universal procedure was sought for plaque assay of eight fish viruses (bluegill myxovirus, channel catfish virus, eel virus, Egtved virus, infectious hematopoietic necrosis virus, infectious pancreatic necrosis virus, lymphocystis virus, and the agent of spring viremia of carp (Rhabdovirus carpio), in dish cultures of various fish cells. Eagle minimal essential medium with sodium bicarbonate-CO2 buffer (Earle’s salt solution) was compared with minimal essential medium buffered principally with tris (hydroxymethyl)aminomethane or N-2-hydroxyethylpiperazine-N′-2′-ethanesulfonic acid at a pH or in the range of 7.6 to 8.0 depending upon temperature. Five fish cell lines collectively capable of replicating all fish viruses thus far isolated were tested and quantitatively found to grow comparably well in the three media. Two-phase (gel-liquid) media incorporating the various buffer systems allowed plaquing at 15 to 33 C either in partial pressures of CO2 or in normal atmosphere, but greater efficiency and sensitivity were obtained with the organic buffers, and, overall, the best results were obtained with tris(hydroxymethyl)aminomethane. Epizootiological data, specific fish cell line response, and plaque morphology permit presumptive identification of most of the agents. At proper pH, use of organic buffers obviates the need for CO2 incubators. Images PMID:4349252

Tris-borate is a poor counterion for RNA: a cautionary tale for RNA folding studies

PubMed Central

Buchmueller, Karen L.; Weeks, Kevin M.

2004-01-01

Native polyacrylamide gel electrophoresis is a powerful approach for visualizing RNA folding states and folding intermediates. Tris-borate has a high-buffering capacity and is therefore widely used in electrophoresis-based investigations of RNA structure and folding. However, the effectiveness of Tris-borate as a counterion for RNA has not been systematically investigated. In a recirculated Hepes/KCl buffer, the catalytic core of the bI5 group I intron RNA undergoes a conformational collapse characterized by a bulk transition midpoint, or Mg1/2, of ∼3 mM, consistent with extensive independent biochemical experiments. In contrast, in Tris-borate, RNA collapse has a much smaller apparent Mg1/2, equal to 0.1 mM, because in this buffer the RNA undergoes a different, large amplitude, folding transition at low Mg2+ concentrations. Analysis of structural neighbors using a short-lived, RNA-tethered, photocrosslinker indicates that the global RNA structure eventually converges in the two buffer systems, as the divalent ion concentration approaches ∼1 mM Mg2+. The weak capacity of Tris-borate to stabilize RNA folding may reflect relatively unfavorable interactions between the bulky Tris-borate ion and RNA or partial coordination of RNA functional groups by borate. Under some conditions, Tris-borate is a poor counterion for RNA and its use merits careful evaluation in RNA folding studies. PMID:15601995

Dual-Analyte Fluorescent Sensor Based on [5]Helicene Derivative with Super Large Stokes Shift for the Selective Determinations of Cu2+ or Zn2+ in Buffer Solutions and Its Application in a Living Cell.

PubMed

Sakunkaewkasem, Siwakorn; Petdum, Anuwut; Panchan, Waraporn; Sirirak, Jitnapa; Charoenpanich, Adisri; Sooksimuang, Thanasat; Wanichacheva, Nantanit

2018-05-10

A new fluorescent sensor, M201-DPA, based on [5]helicene derivative was utilized as dual-analyte sensor for determination of Cu 2+ or Zn 2+ in different media and different emission wavelengths. The sensor could provide selective and bifunctional determination of Cu 2+ in HEPES buffer containing Triton-X100 and Zn 2+ in Tris buffer/methanol without interference from each other and other ions. In HEPES buffer, M201-DPA demonstrated the selective ON-OFF fluorescence quenching at 524 nm toward Cu 2+ . On the other hand, in Tris buffer/methanol, M201-DPA showed the selective OFF-ON fluorescence enhancement upon the addition of Zn 2+ , which was specified by the hypsochromic shift at 448 nm. Additionally, M201-DPA showed extremely large Stokes shifts up to ∼150 nm. By controlling the concentration of Zn 2+ and Cu 2+ in a living cell, the imaging of a HepG2 cellular system was performed, in which the fluorescence of M201-DPA in the blue channel was decreased upon addition of Cu 2+ and was enhanced in UV channel upon addition of Zn 2+ . The detection limits of M201-DPA for Cu 2+ and Zn 2+ in buffer solutions were 5.6 and 3.8 ppb, respectively. Importantly, the Cu 2+ and Zn 2+ detection limits of the developed sensors were significantly lower than permitted Cu 2+ and Zn 2+ concentrations in drinking water as established by the U.S. EPA and WHO.

Effect of protein solution components in the adsorption of Herbaspirillum seropedicae GlnB protein on mica.

PubMed

Ferreira, Cecília F G; Benelli, Elaine M; Klein, Jorge J; Schreiner, Wido; Camargo, Paulo C

2009-10-15

The adsorption of proteins and its buffer solution on mica surfaces was investigated by atomic force microscopy (AFM). Different salt concentration of the Herbaspirillum seropedicae GlnB protein (GlnB-Hs) solution deposited on mica was investigated. This protein is a globular, soluble homotrimer (36kDa), member of PII-like proteins family involved in signal transducing in prokaryote. Supramolecular structures were formed when this protein was deposited onto bare mica surface. The topographic AFM images of the GlnB-Hs films showed that at high salt concentration the supramolecular structures are spherical-like, instead of the typical doughnut-like shape for low salt concentration. AFM images of NaCl and Tris from the buffer solution showed structures with the same pattern as those observed for high salt protein solution, misleading the image interpretation. XPS experiments showed that GlnB protein film covers the mica surface without chemical reaction.

Dialysis buffer with different ionic strength affects the antigenicity of cultured nervous necrosis virus (NNV) suspensions.

PubMed

Gye, Hyun Jung; Nishizawa, Toyohiko

2016-09-02

Nervous necrosis virus (NNV) belongs to the genus Betanodavirus (Nodaviridae). It is highly pathogenic to various marine fishes. Here, we investigated the antigenicity changes of cultured NNV suspensions during 14days of dialyses using a dialysis tube at 1.4×10(4) molecular weight cut off (MWCO) in three different buffers (Dulbecco's phosphate buffered saline (D-PBS), 15mM Tris-HCl (pH 8.0), and deionized water (DIW)). Total NNV antigen titers of cultured NNV suspension varied depending on different dialysis buffers. For example, total NNV antigen titer during D-PBS dialysis was increased once but then decreased. During Tris-HCl dialysis, it was relatively stable. During dialysis in DIW, total NNV antigen titer was increased gradually. These antigenicity changes in NNV suspension might be due to changes in the aggregation state of NNV particles and/or coat proteins (CPs). ELISA values of NNV suspension changed due to changing aggregates state of NNV antigens. NNV particles in suspension were aggregated at a certain level. These aggregates were progressive after D-PBS dialysis, but regressive after Tris-HCl dialysis. The purified NNV particles self-aggregated after dialysis in D-PBS or in Tris-HCl containing 600mM NaCl, but not after dialysis in Tris-HCl or DIW. Quantitative analysis is merited to determine NNV antigens in the highly purified NNV particles suspended in buffer at low salt condition. Copyright © 2016 Elsevier B.V. All rights reserved.

Optimization of protein solution by a novel experimental design method using thermodynamic properties.

PubMed

Kim, Nam Ah; An, In Bok; Lee, Sang Yeol; Park, Eun-Seok; Jeong, Seong Hoon

2012-09-01

In this study, the structural stability of hen egg white lysozyme in solution at various pH levels and in different types of buffers, including acetate, phosphate, histidine, and Tris, was investigated by means of differential scanning calorimetry (DSC). Reasonable pH values were selected from the buffer ranges and were analyzed statistically through design of experiment (DoE). Four factors were used to characterize the thermograms: calorimetric enthalpy (ΔH), temperature at maximum heat flux (T( m )), van't Hoff enthalpy (ΔH( V )), and apparent activation energy of protein solution (E(app)). It was possible to calculate E(app) through mathematical elaboration from the Lumry-Eyring model by changing the scan rate. The transition temperature of protein solution, T( m ), increased when the scan rate was faster. When comparing the T( m ), ΔH( V ), ΔH, and E(app) of lysozyme in various pH ranges and buffers with different priorities, lysozyme in acetate buffer at pH 4.767 (scenario 9) to pH 4.969 (scenario 11) exhibited the highest thermodynamic stability. Through this experiment, we found a significant difference in the thermal stability of lysozyme in various pH ranges and buffers and also a new approach to investigate the physical stability of protein by DoE.

Physicochemical parameters influencing coaggregation between the freshwater bacteria Sphingomonas natatoria 2.1 and Micrococcus luteus 2.13.

PubMed

Min, K R; Zimmer, M N; Rickard, A H

2010-11-01

The aim of this study was to explore the physicochemical parameters that influence coaggregation between the freshwater bacteria Sphingomonas natatoria 2.1 and Micrococcus luteus 2.13. Using visual coaggregation assays, the effect of different buffers, solutions of differing ionic strength, pH, temperature, and viscosity on the degree of coaggregation was assessed. Coaggregation occurred maximally in distilled water but was inhibited when coaggregates were suspended in a commonly-used oral bacterial coaggregation buffer, saline solutions, and Tris-Cl buffers. Coaggregation was weakly expressed in standard laboratory buffers. The ionic strength of inorganic salt solutions required to inhibit coaggregation depended upon the inorganic salt being tested. Coaggregation occurred at a pH of 3-10, between 5 and 80°C and was inhibited in solutions with a viscosity of 22.5 centipoises at 20°C. Inhibition of coaggregation with NaCl impaired biofilm development. When developing buffers to test for coaggregation, the natural liquid environment should be considered. Coaggregation between S. natatoria 2.1 and M. luteus 2.13 is only affected by physicochemical conditions beyond those typically found in natural freshwater ecosystems. Such a robust ability to coaggregate may enhance the ability of S. natatoria 2.1 and M. luteus 2.13 to develop a niche in freshwater biofilms.

In vitro behaviour of three biocompatible glasses in composite implants.

PubMed

Varila, Leena; Lehtonen, Timo; Tuominen, Jukka; Hupa, Mikko; Hupa, Leena

2012-10-01

Poly(L,DL-lactide) composites containing filler particles of bioactive glasses 45S5 and S53P4 were compared with a composite containing a slowly dissolving glass S68. The in vitro reactivity of the composites was studied in simulated body fluid, Tris-buffered solution, and phosphate buffered saline. The high processing temperature induced thermal degradation giving cavities in the composites containing 45S5 and S53P4, while good adhesion of S68 to the polymer was observed. The cavities partly affected the in vitro reactivity of the composites. The degradation of the composites containing the bioactive glasses was faster in phosphate buffered saline than in the two other solutions. Hydroxyapatite precipitation suggesting bone tissue bonding capability was observed on these two composites in all three solutions. The slower dissolution of S68 glass particles and the limited hydroxyapatite precipitation suggested that this glass has potential as a reinforcing composition with the capability to guide bone tissue growth in biodegradable polymer composites.

Polydopamine and Polydopamine-Silane Hybrid Surface Treatments in Structural Adhesive Applications.

PubMed

Tran, Ngon T; Flanagan, David P; Orlicki, Joshua A; Lenhart, Joseph L; Proctor, Kenneth L; Knorr, Daniel B

2018-01-30

Numerous studies have focused on the remarkable adhesive properties of polydopamine, which can bind to substrates with a wide range of surface energies, even under aqueous conditions. This behavior suggests that polydopamine may be an attractive option as a surface treatment in structural bonding applications, where good bond durability is required. Here, we assessed polydopamine as a surface treatment for bonding aluminum plates with an epoxy resin. A model epoxy adhesive consisting of diglycidyl ether of bisphenol A (DGEBA) and Jeffamine D230 polyetheramine was employed, and lap shear measurements (ASTM D1002 10) were made (i) under dry conditions to examine initial bond strength and (ii) after exposure to hot/wet (63 °C in water for 14 days) conditions to assess bond durability. Surprisingly, our results showed that polydopamine alone as a surface treatment provided no benefit beyond that obtained by exposing the substrates to an alkaline solution of tris buffer used for the deposition of polydopamine. This implies that polydopamine has a potential Achilles' heel, namely, the formation of a weak boundary layer that was identified using X-ray photoelectron spectroscopy (XPS) of the fractured surfaces. In fact, for longer deposition times (2.5 and 18 h), the tris buffer-treated surface outperformed the polydopamine surface treatments, suggesting that tris buffer plays a unique role in improving adhesive performance even in the absence of polydopamine. We further showed that the use of polydopamine-3-aminopropyltriethoxysilane (APTES) hybrid surface treatments provided significant improvements in bond durability at extended deposition times relative to both polydopamine and an untreated control.

Improved stability and electrophoretic properties of preformed fluorescent cationic dye-DNA complexes in a taps-tetrapentylammonium buffer in agarose slab gels.

PubMed

Zeng, Z; Clark, S M; Mathies, R A; Glazer, A N

1997-10-01

High-resolution capillary electrophoresis sizing of preformed complexes of bis-intercalating fluorescent dyes with double-stranded DNA has been demonstrated using hydroxyethylcellulose and 3-[tris-(hydroxymethyl) methylamino]-1-propanesulfonic acid-tetrapentylammonium (Taps-NPe+4) buffers (S. M. Clark and R. A. Mathies, Anal. Chem. 69, 1355-1363, 1997). Such capillary electrophoresis separations were unattainable in conventional buffers containing other cations such as Tris+, Na+, and NH+4. We report here the behavior of preformed double-stranded DNA-dye complexes on agarose slab gel electrophoresis in 40 mM Taps-NPe+4, 1 mM H2EDTA, pH 8.2. Upon electrophoresis in this buffer (a) complexes formed at DNA base pairs:dye ratios ranging from 100:1 to 5:1 show the same mobility; (b) the half-lives of DNA-dye complexes with monointercalators are two- to threefold longer than those in commonly used Tris buffers; (c) there is little dye transfer between labeled and unlabeled DNA molecules; and (d) precise two-color sizing of preformed restriction fragment-dye complexes with fluorescent bisintercalators is achieved.

Automatized sspKa measurements of dihydrogen phosphate and Tris(hydroxymethyl) aminomethane in acetonitrile/water mixtures from 20 to 60°C.

PubMed

Acquaviva, A; Tascon, M; Padró, J M; Gagliardi, L G; Castells, C B

2014-09-01

We measured pKa values of Tris(hydroxymethyl)aminomethane and dihydrogen phosphate; both are commonly used to prepare buffers for reverse-phase liquid chromatography (RPLC), in acetonitrile/water mixtures from 0% to 70% (v/v) (64.6% (w/w)) acetonitrile and at 20, 30, 40, 50, and 60°C. The procedure is based on potentiometric measurements of pH of buffer solutions of variable solvent compositions using a glass electrode and a novel automated system. The method consists in the controlled additions of small volumes of a thermostated solution from an automatic buret into another isothermal solution containing exactly the same buffer-component concentrations, but a different solvent composition. The continuous changes in the solvent composition induce changes in the potentials. Thus, only two sequences of additions are needed: increasing the amount of acetonitrile from pure water and decreasing the content of acetonitrile from 70% (v/v) (64.6% (w/w)). In the procedure with homemade apparatus, times for additions, stirring, homogenization, and data acquisition are entirely controlled by software programmed for this specific routine. This rapid, fully automated method was applied to acquire more than 40 potential data covering the whole composition range (at each temperature) in about two hours and allowed a systematic study of the effect of temperature and acetonitrile composition on acid-base equilibria of two widely used substances to control pH close to 7. The experimental pKa results were fitted to empirical functions between pKa and temperature and acetonitrile composition. These equations allowed predictions of pKa to estimate the pH of mixtures at any composition and temperature, which would be very useful, for instance, during chromatographic method development. Copyright © 2014 Elsevier B.V. All rights reserved.

Strategies for the depyrogenation of contaminated immunoglobulin G solutions by histidine-immobilized hollow fiber membrane.

PubMed

Legallais, C; Anspach, F B; Bueno, S M; Haupt, K; Vijayalakshmi, M A

1997-03-28

The depyrogenation of different IgG solutions using the histidine-linked hollow fiber membrane developed in our laboratory is presented here. Three strategies for endotoxin (ET) removal were investigated according to the immobilized histidine's ability to bind different immunoglobulins: (1) ET removal from 1 mg/ml non histidine-binding mouse monoclonal IgG1 (MabCD4) solution was achieved in the presence of acetate buffer (pH 5.0) without any protein loss. (2) For contaminated human IgG, combined adsorption of ET and IgG in the presence of MOPS of Tris buffer was tested, followed by differential elution using increasing salt concentrations. This attempt was not successful since ET were quantitatively found in the IgG elution fraction. (3) Alternatively, it was proposed to adsorb selectively ET in the presence of acetate buffer (pH 5.0) under non binding conditions for human IgG. Human IgG could then be purified if necessary with the same membrane in the presence of MOPS buffer (pH 6.5). With a 1 m2 histidine-PEVA module under these operating conditions, it is estimated that the depyrogenation of 3 l of 1 mg/ml IgG (human or murine) solution containing 80 EU/ml of ET should be possible.

Extraction of glycogen on mild condition lacks AIG fraction.

PubMed

Ghafouri, Z; Rasouli, M

2016-12-01

Extraction of animal tissues with cold water or perchloric acid yields less glycogen than is obtained with hot-alkaline. Extraction with acid and alkaline gives two fractions, acid soluble (ASG) and insoluble glycogen (AIG). The aim of this work is to examine the hypothesis that not all liver glycogen is extractable by Tris-buffer using current techniques. Rat liver was homogenized with Tris-buffer pH 8.3 and extracted for the glycogen fractions, ASG and AIG. The degree of homogenization was changed to remove all glycogen. The content of glycogen was 47.7 ± 1.2 and 11.6 ± 0.8 mg/g wet liver in the supernatant and pellet of the first extraction respectively. About 24% of total glycogen is lost through the first pellet. Increasing the extent of homogenization from 30 to 180 sec and from 15000 to 20000 rpm followed with 30 sec ultrasonication did not improve the extraction. ASG and AIG constitute about 77% and 23% of the pellet glycogen respectively. Extraction with cold Tris-buffer failed to extract glycogen completely.  Increasing the extent of homogenization followed with ultrasonication also did not improve the extraction. Thus it is necessary to re-examine the previous findings obtained by extraction with cold Tris-buffer.

Release of Ciprofloxacin-HCl and Dexamethasone Phosphate by Hyaluronic Acid Containing Silicone Polymers.

PubMed

Nguyen, Darrene; Hui, Alex; Weeks, Andrea; Heynen, Miriam; Joyce, Elizabeth; Sheardown, Heather; Jones, Lyndon

2012-04-19

The purpose of this study was to determine the effect of the covalent incorporation of hyaluronic acid (HA) into conventional hydrogel and hydrogels containing silicone as models for contact lens materials on the uptake and release of the fluoroquinolone antibiotic ciprofloxacin and the anti-inflammatory steroid dexamethasone phosphate. A 3 mg/mL ciprofloxacin solution (0.3% w/v) and a 1 mg/mL dexamethasone phosphate solution (0.1%) was prepared in borate buffered saline. Three hydrogel material samples (pHEMA; pHEMA TRIS; DMAA TRIS) were prepared with and without the covalent incorporation of HA of molecular weight (MW) 35 or 132 kDa. Hydrogel discs were punched from a sheet of material with a uniform diameter of 5 mm. Uptake kinetics were evaluated at room temperature by soaking the discs for 24 h. Release kinetics were evaluated by placing the drug-loaded discs in saline at 34 °C in a shaking water bath. At various time points over 6-7 days, aliquots of the release medium were assayed for drug amounts. The majority of the materials tested released sufficient drug to be clinically relevant in an ophthalmic application, reaching desired concentrations for antibiotic or anti-inflammatory activity in solution. Overall, the silicone-based hydrogels (pHEMA TRIS and DMAA TRIS), released lower amounts of drug than the conventional pHEMA material (p < 0.001). Materials with HA MW132 released more ciprofloxacin compared to materials with HA MW35 and lenses without HA (p < 0.02). Some HA-based materials were still releasing the drug after 6 days.

Biophysical stability of hyFc fusion protein with regards to buffers and various excipients.

PubMed

Lim, Jun Yeul; Kim, Nam Ah; Lim, Dae Gon; Eun, Chang-yong; Choi, Donghoon; Jeong, Seong Hoon

2016-05-01

A novel non-cytolytic hybrid Fc (hyFc) with an intact Ig structure without any mutation in the hyFc region, was developed to construct a long-acting agonistic protein. The stability of interleukin-7 (IL-7) fused with the hyFc (GXN-04) was evaluated to develop early formulations. Various biophysical methods were utilized and three different buffer systems with various pH ranges were investigated including histidine-acetate, sodium citrate, and tris buffers. Various excipients were incorporated into the systems to obtain optimum protein stability. Two evident thermal transitions were observed with the unfolding of IL-7 and hyFc. The Tm and ΔH increased with pH, suggesting increased conformational stability. Increased Z-average size with PDI and decreased zeta potential with pH increase, with the exception of tris buffer, showed aggregation issues. Moreover, tris buffer at higher pH showed aggregation peaks from DLS. Non-ionic surfactants were effective against agitation by outcompeting protein molecules for hydrophobic surfaces. Sucrose and sorbitol accelerated protein aggregation during agitation, but exhibited a protective effect against oxidation, with preferential exclusion favoring the compact states of GXN-04. The stability of GXN-04 was varied by basal buffers and excipients, hence the buffers and excipients need to be evaluated carefully to achieve the maximum stability of proteins. Copyright © 2016 Elsevier B.V. All rights reserved.

Purification and Characterization of the [NiFe]-Hydrogenase of Shewanella oneidensis MR-1 ▿

PubMed Central

Shi, Liang; Belchik, Sara M.; Plymale, Andrew E.; Heald, Steve; Dohnalkova, Alice C.; Sybirna, Kateryna; Bottin, Hervé; Squier, Thomas C.; Zachara, John M.; Fredrickson, James K.

2011-01-01

Shewanella oneidensis MR-1 possesses a periplasmic [NiFe]-hydrogenase (MR-1 [NiFe]-H2ase) that has been implicated in H2 production and oxidation as well as technetium [Tc(VII)] reduction. To characterize the roles of MR-1 [NiFe]-H2ase in these proposed reactions, the genes encoding both subunits of MR-1 [NiFe]-H2ase were cloned and then expressed in an MR-1 mutant without hyaB and hydA genes. Expression of recombinant MR-1 [NiFe]-H2ase in trans restored the mutant's ability to produce H2 at 37% of that for the wild type. Following purification, MR-1 [NiFe]-H2ase coupled H2 oxidation to reduction of Tc(VII)O4− and methyl viologen. Change of the buffers used affected MR-1 [NiFe]-H2ase-mediated reduction of Tc(VII)O4− but not methyl viologen. Under the conditions tested, all Tc(VII)O4− used was reduced in Tris buffer, while in HEPES buffer, only 20% of Tc(VII)O4− was reduced. The reduced products were soluble in Tris buffer but insoluble in HEPES buffer. Transmission electron microscopy analysis revealed that Tc precipitates reduced in HEPES buffer were aggregates of crystallites with diameters of ∼5 nm. Measurements with X-ray absorption near-edge spectroscopy revealed that the reduction products were a mixture of Tc(IV) and Tc(V) in Tris buffer but only Tc(IV) in HEPES buffer. Measurements with extended X-ray adsorption fine structure showed that while the Tc bonding environment in Tris buffer could not be determined, the Tc(IV) product in HEPES buffer was very similar to Tc(IV)O2·nH2O, which was also the product of Tc(VII)O4− reduction by MR-1 cells. These results shows for the first time that MR-1 [NiFe]-H2ase catalyzes Tc(VII)O4− reduction directly by coupling to H2 oxidation. PMID:21724888

Dissolution patterns of biocompatible glasses in 2-amino-2-hydroxymethyl-propane-1,3-diol (Tris) buffer.

PubMed

Fagerlund, S; Hupa, L; Hupa, M

2013-02-01

A continuous flow measurement system with sensitive on-line ion analysis has been applied to study the initial dissolution behaviour of biocompatible glasses in Tris. Altogether 16 glasses with widely varying compositions were studied. The measurement system allowed for quantitative determination of the time-dependent rates of dissolution of sodium, potassium, calcium, magnesium, silicon and phosphorus during the first 10-15 min in contact with Tris solution. The dissolution rates of the different ions showed significant glass to glass variations, but all glasses studied showed one of four distinct dissolution patterns. The ion dissolution rates after an exposure of 1000 s, expressed as the normalized surface-specific mass loss rates, were compared with the in vitro and in vivo reactivity of the glasses as predicted by models in the literature. The results showed a clear correlation between the dissolution rates of the glasses in Tris and their reactivity as measured by other different methods. Consequently, the measured short-term dissolution patterns could be used to determine which glasses are suitable as bioactive, biodegradable, or inert biomaterials for medical devices. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Lethality and injuring the effect of compression and decompression rates of high hydrostatic pressure on Escherichia coli O157:H7 in different matrices

NASA Astrophysics Data System (ADS)

Syed, Qamar Abbas; Buffa, Martin; Guamis, Buenaventura; Saldo, Jordi

2013-03-01

The effect of compression and decompression rates of high hydrostatic pressure (HHP) on Escherichia coli O157:H7 was investigated. Samples of orange juice, skimmed milk and Tris buffer were inoculated with E. coli O157:H7 and subjected to 600 MPa for 3 min at 4°C with fast, medium and slow compression and decompression. Analyses immediately after HHP treatment revealed that E. coli in milk and juice treated with fast compression suffered more than slow compression rates. Slow decompression resulted in higher inactivation of E. coli in all matrices. After overnight storage, highest stress-recovery (1.19 log cfu/mL) was observed in Tris buffer. Healthy cells were<1 log cfu/mL in milk and buffer samples, but no growth was detected in orange juice for any of the treatments immediately after HHP. After 15 days at 4°C, E. coli cells in skimmed milk and Tris buffer recovered significantly, whereas the recovery of sublethally injured cells was inhibited in orange juice.

Swelling kinetics of spray-dried chitosan acetate assessed by magnetic resonance imaging and their relation to drug release kinetics of chitosan matrix tablets.

PubMed

Huanbutta, Kampanart; Sriamornsak, Pornsak; Limmatvapirat, Sontaya; Luangtana-anan, Manee; Yoshihashi, Yasuo; Yonemochi, Etsuo; Terada, Katsuhide; Nunthanid, Jurairat

2011-02-01

Magnetic resonance imaging (MRI) was used to assess in situ swelling behaviors of spray-dried chitosan acetate (CSA) in 0.1N HCl, pH 6.8 and pH 5.0 Tris-HCl buffers. The in vitro drug releases from CSA matrix tablets containing the model drugs, diclofenac sodium and theophylline were investigated in all media using USP-4 apparatus. The effect of chitosan molecular weight, especially in pH 6.8 Tris-HCl, was also studied. In 0.1N HCl, the drug release from the matrix tablets was the lowest in relation to the highest swelling of CSA. The swelling kinetics in Tris-HCl buffers are Fickian diffusion according to their best fit to Higuchi's model as well as the drug release kinetics in all the media. The high swelling rate (k(s)(')) was found to delay the drug release rate (k'). The linear relationship between the swelling and fractions of drug release in Tris-HCl buffers was observed, indicating an important role of the swelling on controlling the drug release mechanism. Additionally, CSA of 200 and 800 kDa chitosan did not swell in pH 6.8 Tris-HCl but disintegrated into fractions, and the drug release from the matrix tablets was the highest. Copyright © 2010 Elsevier B.V. All rights reserved.

Tris-base buffer: a promising new inhibitor for cancer progression and metastasis.

PubMed

Ibrahim-Hashim, Arig; Abrahams, Dominique; Enriquez-Navas, Pedro M; Luddy, Kim; Gatenby, Robert A; Gillies, Robert J

2017-07-01

Neutralizing tumor external acidity with oral buffers has proven effective for the prevention and inhibition of metastasis in several cancer mouse models. Solid tumors are highly acidic as a result of high glycolysis combined with an inadequate blood supply. Our prior work has shown that sodium bicarbonate, imidazole, and free-base (but not protonated) lysine are effective in reducing tumor progression and metastasis. However, a concern in translating these results to clinic has been the presence of counter ions and their potential undesirable side effects (e.g., hypernatremia). In this work, we investigate tris(hydroxymethyl)aminomethane, (THAM or Tris), a primary amine with no counter ion, for its effects on metastasis and progression in prostate and pancreatic cancer in vivo models using MRI and bioluminescence imaging. At an ad lib concentration of 200 mmol/L, Tris effectively inhibited metastasis in both models and furthermore led to a decrease in the expression of the major glucose transporter, GLUT-1. Our results also showed that Tris-base buffer (pH 8.4) had no overt toxicity to C3H mice even at higher doses (400 mmol/L). In conclusion, we have developed a novel therapeutic approach to manipulate tumor extracellular pH (pHe) that could be readily adapted to a clinical trial. © 2017 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

8-aminoquinoline functionalized silica nanoparticles: a fluorescent nanosensor for detection of divalent zinc in aqueous and in yeast cell suspension.

PubMed

Rastogi, Shiva K; Pal, Parul; Aston, D Eric; Bitterwolf, Thomas E; Branen, A Larry

2011-05-01

Zinc is one of the most important transition metal of physiological importance, existing primarily as a divalent cation. A number of sensors have been developed for Zn(II) detection. Here, we present a novel fluorescent nanosensor for Zn(II) detection using a derivative of 8-aminoquinoline (N-(quinolin-8-yl)-2-(3 (triethoxysilyl)propylamino)acetamide (QTEPA) grafted on silica nanoparticles (SiNPs). These functionalized SiNPs were used to demonstrate specific detection of Zn(II) in tris-HCl buffer (pH 7.22), in yeast cell (Saccharomyces cerevisiae) suspension, and in tap water. The silane QTEPA, SiNPs and final product were characterized using solution and solid state nuclear magnetic resonance, Fourier transform infrared, ultraviolet-visible absorption spectroscopy, transmission electron microscopy, elemental analysis, thermogravimetric techniques, and fluorescence spectroscopy. The nanosensor shows almost 2.8-fold fluorescence emission enhancement and about 55 nm red-shift upon excitation with 330 ± 5 nm wavelength in presence of 1 μM Zn(II) ions in tris-HCl (pH 7.22). The presence of other metal ions has no observable effect on the sensitivity and selectivity of nanosensor. This sensor selectively detects Zn(II) ions with submicromolar detection to a limit of 0.1 μM. The sensor shows good applicability in the determination of Zn(II) in tris-HCl buffer and yeast cell environment. Further, it shows enhancement in fluorescence intensity in tap water samples.

Evaluation of the pH- and Thermal Stability of the Recombinant Green Fluorescent Protein (GFP) in the Presence of Sodium Chloride

NASA Astrophysics Data System (ADS)

Ishii, Marina; Kunimura, Juliana Sayuri; Jeng, Hélio Tallon; Vessoni Penna, Thereza Christina; Cholewa, Olivia

The thermal stability of recombinant green fluorescent protein (GFP) in sodium chloride (NaCl) solutions at different concentrations, pH, and temperatures was evaluated by assaying the loss of fluorescence intensity as a measure of denaturation. GFP, extracted from Escherichia coli cells by the three-phase partitioning method and purified through a butyl hydrophobic interaction chromatography (HIC) column, was diluted in water for injection (WFI) (pH 6.0-7.0) and in 10 mM buffer solutions (acetate, pH 5.0; phosphate, pH 7.0; and Tris-EDTA, pH 8.0) with 0.9-30% NaCl or without and incubated at 80-95°C. The extent of protein denaturation was expressed as a percentage of the calculated decimal reduction time (D-value). In acetate buffer (pH 4.84 ±0.12), the mean D-values for 90% reduction in GFP fluorescence ranged from 2.3 to 3.6 min, independent of NaCl concentration and temperature. GFP thermal stability diluted in WFI (pH 5.94±0.60) was half that observed in phosphate buffer (pH 6.08±0.60); but in both systems, D-values decreased linearly with increasing NaCl concentration, with D-values (at 80°C) ranging from 3.44, min (WFI) to 6.1 min (phosphate buffer), both with 30% NaCl. However, D-values in Tris-EDTA (pH 7.65±0.17) were directly dependent on the NaCl concentration and 5-10 times higher than D-values for GFP in WFI at 80°C. GFP pH-and thermal stability can be easily monitored by the convenient measure of fluorescence intensity and potentially be used as an indicator to monitor that processing times and temperatures were attained.

A novel enzymatic method for determination of homocysteine using electrochemical hydrogen sulfide sensor.

PubMed

Zhao, Dong; Liu, Tsan-Zon; Chan, Err-Cheng; Fein, Harry; Zhang, Xueji

2007-05-01

Homocysteine is a sulfur-containing compound produced during metabolism process of methionine. Its uptake in human plasma is believed to be the cause of cardiovascular diseases and many other diseases. An electrochemical method was proposed for selective and quantitative measurement of homocysteine by employing hydrogen sulfide sensor coupled with methionine a, g-lyase. The principle of this method is to measure the evolved hydrogen sulfide from the enzymatic reaction between homocysteine and methionine a, g-lyase. The sensitivities of the measurements at different pH values of the tris buffer solutions and at room temperature peaked to 275 pA/mM at pH 6.5 with detection limit of 150 nM (based on 3 s cutoff). The linearity measurements at pH 6.5 were performed for the homocysteine concentrations range from 0.5 to 200 mM, which is wider than the human blood plasma total homocysteine level of 5 to 100 mM, and the regressive analysis of the experiments gave R2=0.9987. The enzyme also showed the fastest response to homocysteine in the tris buffer solution of pH 7.5 with the current approaching its maximum at 134 seconds. The interference tests against several common agents were carried out, and found that cysteine and methionine were the major two species to introduce measurement problem. The solution to this interference problem was explored and discussed thoroughly based on the preliminary tests. The sensitivities of the experiments against several enzyme concentrations were also performed.

Modulation of Estrogen-Depurinating DNA Adducts by Sulforaphane for Breast Cancer

DTIC Science & Technology

2014-12-01

adducts. NQO1 reduces CE-3,4- 5 quinones back to catechols and GST catalyzes the conjugation of CE-3,4-quinones with glutathione, whereas COMT ... COMT , GSTA1 and β-actin (Sigma) antibodies were made in blocking solution (5% non-fat dry milk in Tris-buffered saline). The blots were incubated...other genes known to influence E2 metabolism, namely CYP1B1 and COMT , were observed (Figure 4A). These inductions exhibited a dose response, with

Recovery of active N-acetyl-D-glucosamine 2-epimerase from inclusion bodies by solubilization with non-denaturing buffers.

PubMed

Lu, Shih-Chin; Lin, Sung-Chyr

2012-01-05

Overexpression of recombinant N-acetyl-D-glucosamine 2-epimerase, one of the key enzymes for the synthesis of N-acetylneuraminic acid, in E. coli led to the formation of protein inclusion bodies. In this study we report the recovery of active epimerase from inclusion bodies by direct solubilization with Tris buffer. At pH 7.0, 25% of the inclusion bodies were solubilized with Tris buffer. The specific activity of the solubilized proteins, 2.08±0.02 U/mg, was similar to that of the native protein, 2.13±0.01 U/mg. The result of circular dichroism spectroscopy analysis indicated that the structure of the solubilized epimerase obtained with pH 7.0 Tris buffer was similar to that of the native epimerase purified from the clarified cell lysate. As expected, the extent of deviation in CD spectra increased with buffer pH. The total enzyme activity recovered by solubilization from inclusion bodies, 170.41±10.06 U/l, was more than 2.5 times higher than that from the clarified cell lysate, 67.32±5.53 U/l. The results reported in this study confirm the hypothesis that the aggregation of proteins into inclusion bodies is reversible and suggest that direct solubilization with non-denaturing buffers is a promising approach for the recovery of active proteins from inclusion bodies, especially for aggregation-prone multisubunit proteins. Copyright © 2011 Elsevier Inc. All rights reserved.

Electrophoretic Characteristics of Outer Membrane Proteins of Neisseria meningitidis,

DTIC Science & Technology

1987-07-01

chemo-organotropic aerobic or facultative microbes, producing catalase and cytochrome oxidase (Morello and Bohnoff, 1980; Reyn, 1974). These bacteria...resolution, the porosity, pH , and TRIS and glycine concentrations in the stacking and separating gels were investigated. The UNCLASSIFIED UNCLASSIFIED /5...stacking gels were 1.7 cm in length and contained, 0.375 M Tris-HCl ( pH 8.8) and 0.1% SDS. The electrode buffer ( pH 8.3 ) consisted of 0.025 M Tris-HCI

Aggregation behavior of fullerenes in aqueous solutions: a capillary electrophoresis and asymmetric flow field-flow fractionation study.

PubMed

Astefanei, Alina; Núñez, Oscar; Galceran, Maria Teresa; Kok, Wim Th; Schoenmakers, Peter J

2015-10-01

In this work, the electrophoretic behavior of hydrophobic fullerenes [buckminsterfullerene (C60), C70, and N-methyl-fulleropyrrolidine (C60-pyrr)] and water-soluble fullerenes [fullerol (C60(OH)24); polyhydroxy small gap fullerene, hydrated (C120(OH)30); C60 pyrrolidine tris acid (C60-pyrr tris acid); and (1,2-methanofullerene C60)-61-carboxylic acid (C60CHCOOH)] in micellar electrokinetic capillary chromatography (MECC) was evaluated. The aggregation behavior of the water-soluble compounds in MECC at different buffer and sodium dodecyl sulfate (SDS) concentrations and pH values of the background electrolyte (BGE) was studied by monitoring the changes observed in the electrophoretic pattern of the peaks. Broad and distorted peaks that can be attributed to fullerene aggregation were obtained in MECC which became narrower and more symmetric by working at low buffer and SDS concentrations (below the critical micelle concentration, capillary zone electrophoresis (CZE) conditions). For the characterization of the suspected aggregates formed (size and shape), asymmetrical flow field-flow fractionation (AF4) and transmission electron microscopy (TEM) were used. The results showed that the increase in the buffer concentration promoted the aggregation of the particles, while the presence of SDS micelles revealed multiple peaks corresponding to particles of different aggregation degrees. Furthermore, MECC has been applied for the first time for the analysis of C60 in two different cosmetic products (i.e., anti-aging serum and facial mask).

Protein brownian rotation at the glass transition temperature of a freeze-concentrated buffer probed by superparamagnetic nanoparticles.

PubMed

Eloi, J-C; Okuda, M; Jones, S E Ward; Schwarzacher, W

2013-06-18

For applications from food science to the freeze-thawing of proteins it is important to understand the often complex freezing behavior of solutions of biomolecules. Here we use a magnetic method to monitor the Brownian rotation of a quasi-spherical cage-shaped protein, apoferritin, approaching the glass transition Tg in a freeze-concentrated buffer (Tris-HCl). The protein incorporates a synthetic magnetic nanoparticle (Co-doped Fe3O4 (magnetite)). We use the magnetic signal from the nanoparticles to monitor the protein orientation. As T decreases toward Tg of the buffer solution the protein's rotational relaxation time increases exponentially, taking values in the range from a few seconds up to thousands of seconds, i.e., orders of magnitude greater than usually accessed, e.g., by NMR. The longest relaxation times measured correspond to estimated viscosities >2 MPa s. As well as being a means to study low-temperature, high-viscosity environments, our method provides evidence that, for the cooling protocol used, the following applies: 1), the concentration of the freeze-concentrated buffer at Tg is independent of its initial concentration; 2), little protein adsorption takes place at the interface between ice and buffer; and 3), the protein is free to rotate even at temperatures as low as 207 K. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

2D spatiotemporal visualization system of expired gaseous ethanol after oral administration for real-time illustrated analysis of alcohol metabolism.

PubMed

Wang, Xin; Ando, Eri; Takahashi, Daishi; Arakawa, Takahiro; Kudo, Hiroyuki; Saito, Hirokazu; Mitsubayashi, Kohji

2010-08-15

A novel 2-dimensional spatiotemporal visualization system of expired gaseous ethanol after oral administration for real-time illustrated analysis of alcohol metabolism has been developed, which employed a low level light CCD camera to detect chemiluminescence (CL) generated by catalytic reactions of standard gaseous ethanol and expired gaseous ethanol after oral administration. First, the optimization of the substrates for visualization and the concentration of luminol solution for CL were investigated. The cotton mesh and 5.0 mmol L(-1) luminol solution were selected for further investigations and this system is useful for 0.1-20.0 mmol L(-1) of H(2)O(2) solution. Then, the effect of pH condition of Tris-HCl buffer solution was also evaluated with CL intensity and under the Tris-HCl buffer solution pH 10.1, a wide calibration range of standard gaseous ethanol (30-400 ppm) was obtained. Finally, expired air of 5 healthy volunteers after oral administration was measured at 15, 30, 45, 60, 75, 90, 105 and 120 min after oral administration, and this system showed a good sensitivity on expired gaseous ethanol for alcohol metabolism. The peaks of expired gaseous ethanol concentration appeared within 30 min after oral administration. During the 30 min after oral administration, the time variation profile based on mean values showed the absorption and distribution function, and the values onward showed the elimination function. The absorption and distribution of expired gaseous ethanol in 5 healthy volunteers following first-order absorption process were faster than the elimination process, which proves efficacious of this system for described alcohol metabolism in healthy volunteers. This system is expected to be used as a non-invasive method to detect VOCs as well as several other drugs in expired air for clinical purpose. Copyright 2010 Elsevier B.V. All rights reserved.

Evaluation of possible reasons for the low phenylalanine ammonia lyase activity in cellulose nitrate membrane microcapsules.

PubMed

Habibi-Moini, S; D'mello, A P

2001-03-14

Microencapsulated phenylalanine ammonia lyase (PAL) exhibits a marked reduction in activity compared to the activity of the free enzyme in pH 8.5 Tris buffer. The purpose of this investigation was to evaluate the contribution of incomplete entrapment, the internal environment of cellulose nitrate membrane microcapsules, the diffusional barrier of the membrane and the microcapsulation process to the low activity of encapsulated PAL. A solution of PAL and 10% w/v hemoglobin was incorporated into cellulose nitrate membrane microcapsules. Hemoglobin incorporation was used as a surrogate marker of PAL entrapment. Using 14C hemoglobin, the encapsulation efficiency was determined to be 70% and suggested that incomplete entrapment might partially account for the low activity of encapsulated PAL. The effect of the internal environment of the microcapsule (10% hemoglobin solution) on PAL activity was evaluated by comparing enzyme activity in 10% w/v hemoglobin solution and pH 8.5 Tris buffer. Similar K(M) and V(max) values of PAL in the two media indicated that the internal environment of the microcapsule did not contribute to the reduction in activity of the encapsulated enzyme. The contribution of a membrane diffusional barrier was determined by breaking the putative barrier and measuring PAL activity in intact and broken microcapsules. Similar activity of PAL in these two conditions is evidence for the lack of a diffusional barrier. The effect of the microencapsulation process on PAL activity was evaluated by comparing K(M) and V(max) of free and encapsulated PAL. Similar K(M) values in these two media suggested that the process did not affect the conformation of PAL. However, encapsulated PAL had a 50% lower V(max) value compared to free PAL, which showed that the microencapsulation process deactivated a substantial proportion of the enzyme.

Isolation of Protective Antigen from Anthrax Toxin by Preparative Isotachophoresis

DTIC Science & Technology

1982-06-14

caosule of polymerized D-olutamic acid which inhibits phago- cytosis and allows the bacillus to establish an infectious focus and elaborate a tripartite...The terminating buffer Tris-c- aminocaproate (Tris-EACA), pH 8.4, was used in the upper electrode (cathode) chamber and in the column. fteen ml of toxin

Purification and Characterization of [NiFe]-Hydrogenase of Shewanella oneidensis MR-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Liang; Belchik, Sara M.; Plymale, Andrew E.

2011-08-02

The γ-proteobacterium Shewanella oneidensis MR-1 possesses a periplasmic [NiFe]-hydrogenase (MR-1 [NiFe]-H2ase) that was implicated in both H2 production and oxidation as well as technetium [Tc(VII)] reduction. To characterize the roles of MR-1 [NiFe]-H2ase in these proposed reactions, the genes encoding both subunits of MR-1 [NiFe]-H2ase were cloned into a protein expression vector. The resulting plasmid was transformed into a MR-1 mutant deficient in H2 formation. Expression of MR-1 [NiFe]-H2ase in trans restored the mutant’s ability to produce H2 at 37% of that for wild type. Following expression, MR-1 [NiFe]-H2ase was purified to near homogeneity. The purified MR-1 [NiFe]-H2ase could couplemore » H2 oxidation to reduction of Tc(VII) and methyl viologen directly. Change of the buffers used affected MR-1 [NiFe]-H2ase-mediated Tc(VII) but not methyl viologen reductions. Under the conditions tested, Tc(VII) reduction was complete in Tris buffer but not in HEPES buffer. The reduced Tc(IV) was soluble in Tris buffer but insoluble in HEPES buffer. Transmission electron microscopy analysis revealed that Tc(IV) precipitates formed in HEPES buffer were packed with crystallites. Although X-ray absorption near-edge spectroscopy measurements confirmed that the reduction products found in both buffers were Tc(IV), extended X-ray adsorption fine-structure measurements revealed that these products were very different. While the product in Tris buffer could not be determined, the Tc(IV) product in HEPES buffer was very similar to Tc(IV)O2•nH2O. These results shows for the first time that MR-1 [NiFe]-H2ase is a bidirectional enzyme that catalyzes both H2 formation and oxidation as well as Tc(VII) reduction directly by coupling H2 oxidation.« less

Effect of buffer at nanoscale molecular recognition interfaces - electrostatic binding of biological polyanions.

PubMed

Rodrigo, Ana C; Laurini, Erik; Vieira, Vânia M P; Pricl, Sabrina; Smith, David K

2017-10-19

We investigate the impact of an over-looked component on molecular recognition in water-buffer. The binding of a cationic dye to biological polyanion heparin is shown by isothermal calorimetry to depend on buffer (Tris-HCl > HEPES > PBS). The heparin binding of self-assembled multivalent (SAMul) cationic micelles is even more buffer dependent. Multivalent electrostatic molecular recognition is buffer dependent as a result of competitive interactions between the cationic binding interface and anions present in the buffer.

Rapid determination of piracetam in human plasma and cerebrospinal fluid by micellar electrokinetic chromatography with sample direct injection.

PubMed

Yeh, Hsin-Hua; Yang, Yuan-Han; Ko, Ju-Yun; Chen, Su-Hwei

2006-07-07

A simple micellar electrokinetic chromatography (MEKC) method with UV detection at 200 nm for analysis of piracetam in plasma and in cerebrospinal fluid (CSF) by direct injection without any sample pretreatment is described. The separation of piracetam from biological matrix was performed at 25 degrees C using a background electrolyte consisting of Tris buffer with sodium dodecyl sulfate (SDS) as the electrolyte solution. Several parameters affecting the separation of the drug from biological matrix were studied, including the pH and concentrations of the Tris buffer and SDS. Under optimal MEKC condition, good separation with high efficiency and short analyses time is achieved. Using imidazole as an internal standard (IS), the linear ranges of the method for the determination of piracetam in plasma and in CSF were all between 5 and 500 microg/mL; the detection limit of the drug in plasma and in CSF (signal-to-noise ratio=3; injection 0.5 psi, 5s) was 1.0 microg/mL. The applicability of the proposed method for determination of piracetam in plasma and CSF collected after intravenous administration of 3g piracetam every 6h and oral administration 1.2g every 6h in encephalopathy patients with aphasia was demonstrated.

Electrophoretic analysis of the major polypeptides of human erythrocyte membranes prepared by low and high osmolarity haemolysis.

PubMed

Zail, S S; Hoek, V D

1975-04-16

Human erythrocyte membranes were prepared in three ways: washing in hypotonic Tris buffer, pH 7.6, by lysis in isotonic Tris buffer pH 7.6 after incubation at 37 degrees C for 2 hours and by ultrasonication in an isotonic medium, pH 7.6. Analysis of the major polypeptides of the erythrocyte membranes by sodium dodecylsulphate polyacrylamide gel electrophoresis revealed a selective depletion of a major polypeptide representing glyceraldehyde-3-phosphate dehydrogenase in the membranes prepared by high osmolarity lysis. The pattern of seperation of the remaining polypeptides was identical in the 3 different membrane preparations.

CSE-MECC two-dimensional capillary electrophoresis analysis of proteins in the mouse tumor cell (AtT-20) homogenate

PubMed Central

Chen, Xingguo; Fazal, Md. Abul; Dovichi, Norman J.

2007-01-01

Two-dimensional capillary electrophoresis was used for the separation of proteins and biogenic amines from the mouse AtT-20 cell line. The first-dimension capillary contained a TRIS-CHES-SDS-dextran buffer to perform capillary sieving electrophoresis, which is based on molecular weight of proteins. The second-dimension capillary contained a TRIS-CHES-SDS buffer for micel1ar electrokinetic capillary chromatography. After a 61 seconds preliminary separation, fractions from the first-dimension capillary were successively transferred to the second-dimension capillary, where they further separated by MECC. The two-dimensional separation required 60 minutes. PMID:17637850

Sodium Is Not Essential for High Bioactivity of Glasses

PubMed Central

Chen, Xiaojing; Chen, Xiaohui; Brauer, Delia S.; Wilson, Rory M.; Law, Robert V.; Hill, Robert G.; Karpukhina, Natalia

2017-01-01

This study aims to demonstrate that excellent bioactivity of glass can be achieved without the presence of an alkali metal component in glass composition. In vitro bioactivity of two sodium-free glasses based on the quaternary system SiO2-P2O5-CaO-CaF2 with 0 and 4.5 mol% CaF2 content was investigated and compared with the sodium containing glasses with equivalent amount of CaF2. The formation of apatite after immersion in Tris buffer was followed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), 31P and 19F solid state MAS-NMR. The dissolution study was completed by ion release measurements in Tris buffer. The results show that sodium free bioactive glasses formed apatite at 3 hours of immersion in Tris buffer, which is as fast as the corresponding sodium containing composition. This signifies that sodium is not an essential component in bioactive glasses and it is possible to make equally degradable bioactive glasses with or without sodium. The results presented here also emphasize the central role of the glass compositions design which is based on understanding of structural role of components and/or predicting the network connectivity of glasses. PMID:29271977

Sodium Is Not Essential for High Bioactivity of Glasses.

PubMed

Chen, Xiaojing; Chen, Xiaohui; Brauer, Delia S; Wilson, Rory M; Law, Robert V; Hill, Robert G; Karpukhina, Natalia

2017-12-01

This study aims to demonstrate that excellent bioactivity of glass can be achieved without the presence of an alkali metal component in glass composition. In vitro bioactivity of two sodium-free glasses based on the quaternary system SiO 2 -P 2 O 5 -CaO-CaF 2 with 0 and 4.5 mol% CaF 2 content was investigated and compared with the sodium containing glasses with equivalent amount of CaF 2 . The formation of apatite after immersion in Tris buffer was followed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), 31 P and 19 F solid state MAS-NMR. The dissolution study was completed by ion release measurements in Tris buffer. The results show that sodium free bioactive glasses formed apatite at 3 hours of immersion in Tris buffer, which is as fast as the corresponding sodium containing composition. This signifies that sodium is not an essential component in bioactive glasses and it is possible to make equally degradable bioactive glasses with or without sodium. The results presented here also emphasize the central role of the glass compositions design which is based on understanding of structural role of components and/or predicting the network connectivity of glasses.

The effects of buffers and pH on the thermal stability, unfolding and substrate binding of RecA.

PubMed

Metrick, Michael A; Temple, Joshua E; MacDonald, Gina

2013-12-31

The Escherichia coli protein RecA is responsible for catalysis of the strand transfer reaction used in DNA repair and recombination. Previous studies in our lab have shown that high concentrations of salts stabilize RecA in a reverse-anionic Hofmeister series. Here we investigate how changes in pH and buffer alter the thermal unfolding and cofactor binding. RecA in 20mM HEPES, MES, Tris and phosphate buffers was studied in the pH range from 6.5 to 8.5 using circular dichroism (CD), infrared (IR) and fluorescence spectroscopies. The results show all of the buffers studied stabilize RecA up to 50°C above the Tris melting temperature and influence RecA's ability to nucleate on double-stranded DNA. Infrared and CD spectra of RecA in the different buffers do not show that secondary structural changes are associated with increased stability or decreased ability to nucleate on dsDNA. These results suggest the differences in stability arise from decreasing positive charge and/or buffer interactions. © 2013. Published by Elsevier B.V. All rights reserved.

Kinetic behaviour of calf intestinal alkaline phosphatase with pNPP.

PubMed

Chaudhuri, Gouri; Chatterjee, Saswata; Venu-Babu, P; Ramasamy, K; Thilagaraj, W Richard

2013-02-01

The hydrolysis of p-nitrophenyl phosphate (pNPP) by calf intestinal alkaline phosphatase (CIAP) was investigated with respect to kinetic parameters such as V(max), K(m) and K(cat) under varying pH, buffers, substrate concentration, temperature and period of incubation. Highest activity was obtained with Tris-HCl at pH 11, while in the case of glycine-NaOH buffer the peak activity was recorded at pH 9.5. The enzyme showed the following kinetic characteristics with pNPP in 50 mM Tris-HCl at pH 11 and 100 mM glycine-NaOH at pH 9.5 at an incubation temperature of 37 degrees C: V(max), 3.12 and 1.6 micromoles min(-1) unit(-1); K(m), 7.6 x 10(-4) M and 4 x 10(-4) M; and K(cat), 82.98 s(-1) and 42.55 s(-1), respectively. CIAP displayed a high temperature optimum of 45 degrees C at pH 11. The kinetic behaviour of the enzyme under different parameters suggested that the enzyme might undergo subtle conformational changes in response to the buffers displaying unique characteristics. Bioprecipitation of Cu2+ from 50 ppm of CuCl2 solution was studied where 64.3% of precipitation was obtained. P(i) generated from CIAP-mediated hydrolysis of pNPP was found to bind with copper and precipitated as copper-phosphate. Thus, CIAP could be used as a test candidate in bioremediation of heavy metals from industrial wastes through generation of metal-phosphate complexes.

Electrogenerated chemiluminescence of tris(2-phenylpyridine)iridium(III) in water, acetonitrile and trifluorethanol.

PubMed

Robinson, Wesley D; Richter, Mark M

2015-02-01

The spectroscopic, electrochemical and coreactant electrogenerated chemiluminescence (ECL) properties of Ir(ppy)3 (where ppy = 2-phenylpyridine) have been obtained in aqueous buffered (KH2PO4), 50 : 50 (v/v) acetonitrile-aqueous buffered (MeCN-KH2PO4) and 30% trifluoroethanol (TFE) solutions. Tri-n-propylamine was used as the oxidative-reductive ECL coreactant. The photoluminescence (PL) efficiency (ϕem) of Ir(ppy)3 in TFE (ϕem ≈ 0.029) was slightly higher than in 50 : 50 MeCN-KH2PO4 (ϕem ≈ 0.0021) and water (ϕem ≈ 0.00016) compared to a Ru(bpy)32+ standard solution in water (Φem ≈ 0.042). PL and ECL emission spectra were nearly identical in all three solvents, with dual emission maxima at 510 and 530 nm. The similarity between the ECL and PL spectra indicate that the same excited state is probably formed in both experiments. ECL efficiencies (ϕecl) in 30% TFE solution (ϕecl = 0.0098) were higher than aqueous solution (ϕecl = 0.00092) system yet lower than a 50% MeCN-KH2PO4 solution (ϕecl = 0.0091). Copyright © 2014 John Wiley & Sons, Ltd.

Optimizing buffering chemistry to maintain near neutral pH of broiler feed during pre-enrichment for Salmonella.

PubMed

Berrang, M E; Cosby, D E; Cox, N A; Cason, J A; Richardson, K E

2015-12-01

Salmonella is a human pathogen that can accompany live broilers to the slaughter plant, contaminating fully processed carcasses. Feed is one potential source of Salmonella to growing broilers. Monitoring feed for the presence of Salmonella is part of good agricultural practice. The first step in culturing feed for Salmonella (which may be at low numbers and sub-lethally stressed) is to add it to a pre-enrichment broth which is incubated for 24 h. During the course of pre-enrichment, extraneous bacteria metabolize carbohydrates in some feed and excrete acidic byproducts, causing the pH to drop dramatically. An acidic pre-enrichment pH can injure or kill Salmonella resulting in a failure to detect, even if it is present and available to infect chickens. The objective of this study was to test an array of buffering chemistries to prevent formation of an injurious acidic environment during pre-enrichment of feed in peptone water. Five grams of feed were added to 45 mL of peptone water buffered with carbonate, Tris pH 8, and phosphate buffering ingredients individually and in combination. Feed was subjected to a pre-enrichment at 35°C for 24 h; pH was measured at 0, 18, and 24 h. Standard phosphate buffering ingredients at concentrations up to 4 times the normal formulation were unable to fully prevent acidic conditions. Likewise, carbonate and Tris pH 8 were not fully effective. The combination of phosphate, carbonate, and Tris pH 8 was the most effective buffer tested. It is recommended that a highly buffered pre-enrichment broth be used to examine feed for the presence of Salmonella. Published by Oxford University Press on behalf of Poultry Science Association 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Purification of α-glucosidase from mouse intestine by countercurrent chromatography coupled with a reverse micelle solvent system.

PubMed

He, Kai; Zou, Zongyao; Hu, Yinran; Yang, Yong; Xiao, Yubo; Gao, Pincao; Li, Xuegang; Ye, Xiaoli

2016-02-01

Countercurrent chromatography coupled with a reverse micelle solvent was applied to separate α-glucosidase, which is stable at pH 6.0-8.8, 15-50°C. The separation conditions are as follows: stationary phase: pH 4.0 Tris-HCl buffer phase containing 50 mM Tris-HCl and 50 mM KCl; mobile phase A: isooctane containing 50 mM anionic surfactant sodium di(2-ethylhexyl)sulfosuccinate; mobile phase B: 50 mM Tris-HCl buffer containing 500 mM KCl (pH 8.0); In total, 25 mL (23.9 mg) crude enzyme was injected through the injection valve, the enzymatic reaction and sodium dodecylsulfate polyacrylamide gel electrophoresis results imply that the activity of purified α-glucosidase is 6.63-fold higher than that of the crude enzyme. Therefore, countercurrent chromatography coupled with a reverse micelle solvent is capable for protein separation and enrichment. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of magnesia on the degradability and bioactivity of sol-gel derived SiO2-CaO-MgO-P2O5 system glasses.

PubMed

Ma, J; Chen, C Z; Wang, D G; Jiao, Y; Shi, J Z

2010-11-01

Mesoporous 58SiO(2)-(38-x)CaO-xMgO-4P(2)O(5) glasses (where x=0, 5, 10 and 20 mol%) have been prepared by the sol-gel synthesis route. The effects of the substitution of MgO for CaO on glass degradation and bioactivity were studied in tris-(hydroxymethyl)-aminomethane and hydrochloric acid buffer solution (Tris-HCl) and simulated body fluid (SBF), respectively. It is observed that the synthesized glasses with various MgO contents possess the similar textural properties. The studies of in vitro degradability and bioactivity show that the rate of glass degradation gradually decreases with the increase of MgO and the formation of apatite layer on glass surface is retarded. The influences of the composition upon glass properties are explained in terms of their internal structures. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Preconcentration of DNA using magnetic ionic liquids that are compatible with real-time PCR for rapid nucleic acid quantification.

PubMed

Emaus, Miranda N; Clark, Kevin D; Hinners, Paige; Anderson, Jared L

2018-04-28

Nucleic acid extraction and purification represents a major bottleneck in DNA analysis. Traditional methods for DNA purification often require reagents that may inhibit quantitative polymerase chain reaction (qPCR) if not sufficiently removed from the sample. Approaches that employ magnetic beads may exhibit lower extraction efficiencies due to sedimentation and aggregation. In this study, four hydrophobic magnetic ionic liquids (MILs) were investigated as DNA extraction solvents with the goal of improving DNA enrichment factors and compatibility with downstream bioanalytical techniques. By designing custom qPCR buffers, we directly incorporated DNA-enriched MILs including trihexyl(tetradecyl)phosphonium tris(hexafluoroacetylaceto)nickelate(II) ([P 6,6,6,14 + ][Ni(hfacac) 3 - ]), [P 6,6,6,14 + ] tris(hexafluoroacetylaceto)colbaltate(II) ([Co(hfacac) 3 - ]), [P 6,6,6,14 + ] tris(hexafluoroacetylaceto)manganate(II) ([Mn(hfacac) 3 - ]), or [P 6,6,6,14 + ] tetrakis(hexafluoroacetylaceto)dysprosate(III) ([Dy(hfacac) 4 - ]) into reaction systems, thereby circumventing the need for time-consuming DNA recovery steps. Incorporating MILs into the reaction buffer did not significantly impact the amplification efficiency of the reaction (91.1%). High enrichment factors were achieved using the [P 6,6,6,14 + ][Ni(hfacac) 3 - ] MIL for the extraction of single-stranded and double-stranded DNA with extraction times as short as 2 min. When compared to a commercial magnetic bead-based platform, the [P 6,6,6,14 + ][Ni(hfacac) 3 - ] MIL was capable of producing higher enrichment factors for single-stranded DNA and similar enrichment factors for double-stranded DNA. The MIL-based method was applied for the extraction and direct qPCR amplification of mutation prone-KRAS oncogene fragment in plasma samples. Graphical abstract Magnetic ionic liquid solvents are shown to preconcentrate sufficient KRAS DNA template from an aqueous solution in as short as 2 min without using chaotropic salts or toxic organic solvents. By using custom-designed qPCR buffers, DNA can be directly amplified and quantified from four MILs examined in this study.

Rapid and sensitive analytical method for monitoring of 12 organotin compounds in natural waters.

PubMed

Vahčič, Mitja; Milačič, Radmila; Sčančar, Janez

2011-03-01

A rapid analytical method for the simultaneous determination of 12 different organotin compounds (OTC): methyl-, butyl-, phenyl- and octyl-tins in natural water samples was developed. It comprises of in situ derivatisation (by using NaBEt4) of OTC in salty or fresh water sample matrix adjusted to pH 6 with Tris-citrate buffer, extraction of ethylated OTC into hexane, separation of OTC in organic phase on 15 m GC column and subsequent quantitative determination of separated OTC by ICP-MS. To optimise the pH of ethylation, phosphate, carbonate and Tris-citrate buffer were investigated alternatively to commonly applied sodium acetate - acetic acid buffer. The ethylation yields in Tris-citrate buffer were found to be better for TBT, MOcT and DOcT in comparison to commonly used acetate buffer. Iso-octane and hexane were examined as organic phase for extraction of ethylated OTC. The advantage of hexane was in its ability for quantitative determination of TMeT. GC column of 15 m in length was used for separation of studied OTC under the optimised separation conditions and its performances compared to 30 m column. The analytical method developed enables sensitive simultaneous determination of 12 different OTC and appreciably shortened analysis time in larger series of water samples. LOD's obtained for the newly developed method ranged from 0.05-0.06 ng Sn L-1 for methyl-, 0.11-0.45 ng Sn L-1 for butyl-, 0.11-0.16 ng Sn L-1 for phenyl-, and 0.07-0.10 ng Sn L-1 for octyl-tins. By applying the developed analytical method, marine water samples from the Northern Adriatic Sea containing mainly butyl- and methyl-tin species were analysed to confirm the proposed method's applicability.

Buffer capacity of 4% succinylated gelatin does not provide any advantages over acidic 6% hydroxyethyl starch 130/0.4 for acid-base balance during experimental mixed acidaemia in a porcine model.

PubMed

Esche, V; Russ, M; Melzer, S; Grossmann, B; Boemke, W; Unger, J K

2008-11-01

Four percent gelatine is an alkaline compound due to NH2 groups, whereas 6% hydroxyethyl starch 130/0.4 (HES130) has acidic features. We investigated whether these solutions lead to differences in acid-base balance in pigs during acidaemia and correction of pH. Anaesthetized pigs were randomized to HES130 or gelatine infusion (n = 5 per group). Animals received acid infusion (0.4 M solution of lactic acid and HCl diluted in normal saline) and low tidal volume ventilation (6-7 mL kg(-1), PaCO2 of 80-85 mmHg, pH 7.19-7.24). Measurements were made before and after induction of acidaemia, before and after correction of pH with haemofiltration (continuous venovenous haemofiltration) and tris-hydroxymethylaminomethane infusion. We measured parameters describing acid-base balance according to Stewart's approach, ketone body formation, oxygen delivery, haemodynamics, diuresis and urinary pH. Acid-base balance did not differ significantly between the groups. In HES130-treated pigs, the haemodilution-based drop of haemoglobin (1.4 +/- 1.0 g dL(-1), median +/- SD) was paralleled by an increase in the cardiac output (0.5 +/- 0.4 L min(-1). Lacking increases in cardiac output, gelatine-treated pigs demonstrated a reduction in oxygen delivery (149.4 +/- 106.0 mL min(-1)). Tris-hydroxymethylaminomethane volumes required for pH titration to desired values were significantly higher in the gelatine group (0.7 +/- 0.1 mL kg(-1) h(-1) vs. HES130: 0.5 +/- 0.2 mL kg(-1) h(-1)). The buffer capacity of gelatine did not lead to favourable differences in acid-base balance in comparison to HES130.

A hexa-quinoline based C3-symmetric chemosensor for dual sensing of zinc(ii) and PPi in an aqueous medium via chelation induced "OFF-ON-OFF" emission.

PubMed

Sinha, Sanghamitra; Chowdhury, Bijit; Adarsh, Nayarassery N; Ghosh, Pradyut

2018-05-15

A quinoline-based C3-symmetric fluorescent probe (1), N,N',N''-((2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene))tris(1-(quinolin-2-yl)-N-(quinolin-2-ylmethyl)methanamine), has been developed which can selectively detect Zn2+ without the interference of Cd2+via significant enhancement in emission intensity (fluorescence "turn-ON") associated with distinct fluorescence colour changes and very low detection limits (35.60 × 10-9 M in acetonitrile and 29.45 × 10-8 M in 50% aqueous buffer (10 mM HEPES, pH = 7.4) acetonitrile media). Importantly, this sensor is operative with a broad pH window (pH 4-10). The sensing phenomenon has been duly studied through UV-vis, steady-state, and time-resolved fluorescence spectroscopic methods indicating 1 : 3 stoichiometric binding between 1 and Zn2+ which is further corroborated by 1H NMR studies. Density functional theoretical (DFT) calculations provide the optimized molecular geometry and properties of the zinc complex, 1[Zn(ClO4)]33+, which is proposed to be formed in acetonitrile. The results are in line with the solution-state experimental findings. The single crystal X-ray study provides the solid state structure of the trinuclear Zn2+ complex showing solubility in an aqueous buffer (10 mM HEPES, pH = 7.4). Finally, the resulting trinuclear Zn2+ complex has been utilized as a fluorescence "turn-OFF" sensor for the selective detection of pyrophosphate in a 70% aqueous buffer (10 mM HEPES, pH = 7.4) acetonitrile solvent with a nanomolar detection limit (45.37 × 10-9 M).

Protein Buffering in Model Systems and in Whole Human Saliva

PubMed Central

Lamanda, Andreas; Cheaib, Zeinab; Turgut, Melek Dilek; Lussi, Adrian

2007-01-01

The aim of this study was to quantify the buffer attributes (value, power, range and optimum) of two model systems for whole human resting saliva, the purified proteins from whole human resting saliva and single proteins. Two model systems, the first containing amyloglucosidase and lysozyme, and the second containing amyloglucosidase and α-amylase, were shown to provide, in combination with hydrogencarbonate and di-hydrogenphosphate, almost identical buffer attributes as whole human resting saliva. It was further demonstrated that changes in the protein concentration as small as 0.1% may change the buffer value of a buffer solution up to 15 times. Additionally, it was shown that there was a protein concentration change in the same range (0.16%) between saliva samples collected at the time periods of 13:00 and others collected at 9:00 am and 17:00. The mode of the protein expression changed between these samples corresponded to the change in basic buffer power and the change of the buffer value at pH 6.7. Finally, SDS Page and Ruthenium II tris (bathophenantroline disulfonate) staining unveiled a constant protein expression in all samples except for one 50 kDa protein band. As the change in the expression pattern of that 50 kDa protein band corresponded to the change in basic buffer power and the buffer value at pH 6.7, it was reasonable to conclude that this 50 kDa protein band may contain the protein(s) belonging to the protein buffer system of human saliva. PMID:17327922

Implications for Ophthalmic Formulations: Ocular Buffers Show Varied Cytotoxic Impact on Human Corneal-Limbal and Human Conjunctival Epithelial Cells.

PubMed

Schuerer, Nadine; Stein, Elisabeth; Inic-Kanada, Aleksandra; Pucher, Marion; Hohenadl, Christine; Bintner, Nora; Ghasemian, Ehsan; Montanaro, Jacqueline; Barisani-Asenbauer, Talin

2017-06-01

To investigate toxicity associated with buffers commonly used in topical ocular drug formulations using a human corneal-limbal epithelial (HCLE) and a human conjunctival epithelial (HCjE) cell model. HCLE and HCjE cells were incubated for 10, 30, or 60 minutes with 4 different buffers based on borate, citrate, phosphate, and Tris-HCl at 10, 50, and 100 mM concentrations. To detect possible delayed effects on cell viability, after 60 minutes of buffer incubation, cells were further incubated for 24 hours with a cell medium. Cell viability was determined using a colorimetric XTT-based assay. The morphology of cells was also investigated. HCjE cells showed more sensitivity to buffer incubation than HCLE cells. The 100 mM phosphate buffer displayed significant delayed effects on cell viability of HCLE 16.8 ± 4.8% and HCjE 39.2 ± 6.1% cells after 60 minutes of exposure (P < 0.05). HCjE cell viability was reduced after 60 minutes incubations with 50 and 100 mM citrate buffer to 42.8 ± 6.5% and 39.3 ± 7.9%, respectively, and even lower percentages at the delayed time point (both P < 0.05). HCLE cell morphology was distinctly altered by 100 mM phosphate and Tris buffers after 30 minutes, whereas HCjE cells already showed marked changes after 10 minutes of exposure to 100 mM citrate and phosphate buffers. We observed a time-dependent decrease of viability in both HCLE and HCjE cells exposed to higher buffer concentrations. Therefore, we propose further in vivo studies to translate these finding to humans to discern the real effects of the buffer concentration in eye drops on the ocular surface.

Implications for Ophthalmic Formulations: Ocular Buffers Show Varied Cytotoxic Impact on Human Corneal–Limbal and Human Conjunctival Epithelial Cells

PubMed Central

Schuerer, Nadine; Stein, Elisabeth; Inic-Kanada, Aleksandra; Pucher, Marion; Hohenadl, Christine; Bintner, Nora; Ghasemian, Ehsan; Montanaro, Jacqueline

2017-01-01

Purpose: To investigate toxicity associated with buffers commonly used in topical ocular drug formulations using a human corneal–limbal epithelial (HCLE) and a human conjunctival epithelial (HCjE) cell model. Methods: HCLE and HCjE cells were incubated for 10, 30, or 60 minutes with 4 different buffers based on borate, citrate, phosphate, and Tris-HCl at 10, 50, and 100 mM concentrations. To detect possible delayed effects on cell viability, after 60 minutes of buffer incubation, cells were further incubated for 24 hours with a cell medium. Cell viability was determined using a colorimetric XTT–based assay. The morphology of cells was also investigated. Results: HCjE cells showed more sensitivity to buffer incubation than HCLE cells. The 100 mM phosphate buffer displayed significant delayed effects on cell viability of HCLE 16.8 ± 4.8% and HCjE 39.2 ± 6.1% cells after 60 minutes of exposure (P < 0.05). HCjE cell viability was reduced after 60 minutes incubations with 50 and 100 mM citrate buffer to 42.8 ± 6.5% and 39.3 ± 7.9%, respectively, and even lower percentages at the delayed time point (both P < 0.05). HCLE cell morphology was distinctly altered by 100 mM phosphate and Tris buffers after 30 minutes, whereas HCjE cells already showed marked changes after 10 minutes of exposure to 100 mM citrate and phosphate buffers. Conclusions: We observed a time-dependent decrease of viability in both HCLE and HCjE cells exposed to higher buffer concentrations. Therefore, we propose further in vivo studies to translate these finding to humans to discern the real effects of the buffer concentration in eye drops on the ocular surface. PMID:28399036

Cullin 5 Expression in the Rat: Cellular and Tissue Distribution, and Changes in Response to Water Deprivation and Hemorrhagic Shock

DTIC Science & Technology

2003-02-28

of Health p53 tumor suppressor PBS phosphate buffered saline PCO2 partial pressure of carbon dioxide PO2 partial pressure of oxygen PCR...buffered saline TTBS tween-20 tris buffered saline TonEBP tonicity-response enhancer binding protein TSNRP TriService Nursing Research Program...growth and metabolism (Hochstrasser, 1995; Deshaies, 1999). Although traditionally seen as no more than a means of eliminating no longer needed

Comparative analyses of universal extraction buffers for assay of stress related biochemical and physiological parameters.

PubMed

Han, Chunyu; Chan, Zhulong; Yang, Fan

2015-01-01

Comparative efficiency of three extraction solutions, including the universal sodium phosphate buffer (USPB), the Tris-HCl buffer (UTHB), and the specific buffers, were compared for assays of soluble protein, free proline, superoxide radical (O2∙-), hydrogen peroxide (H2O2), and the antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (POD), ascorbate peroxidase (APX), glutathione peroxidase (GPX), and glutathione reductase (GR) in Populus deltoide. Significant differences for protein extraction were detected via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional electrophoresis (2-DE). Between the two universal extraction buffers, the USPB showed higher efficiency for extraction of soluble protein, CAT, GR, O2∙-, GPX, SOD, and free proline, while the UTHB had higher efficiency for extraction of APX, POD, and H2O2. When compared with the specific buffers, the USPB showed higher extraction efficiency for measurement of soluble protein, CAT, GR, and O2∙-, parallel extraction efficiency for GPX, SOD, free proline, and H2O2, and lower extraction efficiency for APX and POD, whereas the UTHB had higher extraction efficiency for measurement of POD and H2O2. Further comparisons proved that 100 mM USPB buffer showed the highest extraction efficiencies. These results indicated that USPB would be suitable and efficient for extraction of soluble protein, CAT, GR, GPX, SOD, H2O2, O2∙-, and free proline.

Solution Preserves Nucleic Acids in Body-Fluid Specimens

NASA Technical Reports Server (NTRS)

Pierson, Duane L.; Stowe, Raymond P.

2004-01-01

A solution has been formulated to preserve deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) in specimens of blood, saliva, and other bodily fluids. Specimens of this type are collected for diagnostic molecular pathology, which is becoming the method of choice for diagnosis of many diseases. The solution makes it possible to store such specimens at room temperature, without risk of decomposition, for subsequent analysis in a laboratory that could be remote from the sampling location. Thus, the solution could be a means to bring the benefits of diagnostic molecular pathology to geographic regions where refrigeration equipment and diagnostic laboratories are not available. The table lists the ingredients of the solution. The functions of the ingredients are the following: EDTA chelates divalent cations that are necessary cofactors for nuclease activity. In so doing, it functionally removes these cations and thereby retards the action of nucleases. EDTA also stabilizes the DNA helix. Tris serves as a buffering agent, which is needed because minor contaminants in an unbuffered solution can exert pronounced effects on pH and thereby cause spontaneous degradation of DNA. SDS is an ionic detergent that inhibits ribonuclease activity. SDS has been used in some lysis buffers and as a storage buffer for RNA after purification. The use of the solution is straightforward. For example, a sample of saliva is collected by placing a cotton roll around in the subject's mouth until it becomes saturated, then the cotton is placed in a collection tube. Next, 1.5 mL of the solution are injected directly into the cotton and the tube is capped for storage at room temperature. The effectiveness of the solution has been demonstrated in tests on specimens of saliva containing herpes simplex virus. In the tests, the viral DNA, as amplified by polymerase chain reaction, was detected even after storage for 120 days.

Semen coagulum liquefaction, sperm activation and cryopreservation of capuchin monkey (Cebus apella) semen in coconut water solution (CWS) and TES-TRIS.

PubMed

Oliveira, Karol G; Miranda, Stefania A; Leão, Danuza L; Brito, Adriel B; Santos, Regiane R; Domingues, Sheyla F S

2011-01-01

The objectives of the present study were to test the effect of coconut water solution and TES-TRIS on the seminal coagulum liquefaction, sperm activation in fresh diluted semen, and on the cryopreservation of semen from capuchin monkeys (Cebus apella). Semen was collected from six males by electro-ejaculation, diluted in TES-TRIS or coconut water solution (CWS), and incubated at 35°C until the coagulated fraction of the semen was completely liquefied. In the experiment I, after liquefaction, samples were diluted in TES-TRIS or CWS, plus 6 and 10mM/mL of caffeine. Sperm motility and vigor were evaluated during 5h. For experiment II, after liquefaction, semen samples were extended in TES-TRIS (3.5% glycerol in the final solution) or CWS (2.5% glycerol in the final solution), cryopreserved and stored in liquid nitrogen for 1 week. The seminal coagulum was liquefied in (mean±SDM) 4.5±1.7 and 2.8±1.1h in TES-TRIS and CWS, respectively. Sperm were motile in TES-TRIS and CWS for 5.0±1.4 and 1.0±0.5h, respectively. The mean motility in this period was 38±22% (TES-TRIS) and 22.0±16.0 (CWS). Motility increased after caffeine addition only in samples diluted in CWS containing 6mM (22.5±16.0) or 10mM (28.0±19.0) caffeine. Post-thaw live sperm percentage was 26.2% in TES-TRIS and 13.2% in CWS. For cryopreservation of semen from C. apella TES-TRIS (3.5% glycerol) was more appropriate than CWS (2.5% glycerol). CWS+caffeine potentially increase sperm motility and may be useful in artificial insemination of fresh diluted semen. Copyright © 2010 Elsevier B.V. All rights reserved.

Separation of Native Allophycocyanin and R-Phycocyanin from Marine Red Macroalga Polysiphonia urceolata by the Polyacrylamide Gel Electrophoresis Performed in Novel Buffer Systems

PubMed Central

Wang, Yu; Gong, Xueqin; Wang, Shumei; Chen, Lixue; Sun, Li

2014-01-01

Three buffer systems of Imidazole−Acetic acid, HEPES−Imidazole/Bis-tris and Bis-tris−HEPES−MES were designed based on the principle of discontinuous polyacrylamide gel electrophoresis (PAGE) for the native PAGE which could be performed in pH 7.0 and 6.5 in order to analyze and prepare the minor components of allophycocyanin (AP) and R-phycocyanin (R-PC) from marine red macroalga Polysiphonia urceolata. These AP and R-PC phycobiliproteins are easily denatured in alkaline environments. The obtained results demonstrated that the PAGE modes performed in the buffer systems of HEPES−Imidazole/Bis-tris and Bis-tris−HEPES−MES gave the satisfactory resolution and separation of AP and R-PC proteins. The absorption and fluorescence spectra of the AP and R-PC proteins which were prepared by the established PAGE modes proved that they maintained natural spectroscopic characteristics. The established PAGE modes may also provide useful references and selections for some other proteins that are sensitive to alkaline environments or are not effectively separated by the classical PAGE modes performed normally in alkaline buffer systems. PMID:25166028

Purification, characterization, and crystallization of Crocodylus siamensis hemoglobin.

PubMed

Jandaruang, Jinda; Siritapetawee, Jaruwan; Songsiriritthigul, Chomphunuch; Preecharram, Sutthidech; Azuma, Taoka; Dhiravisit, Apisak; Fukumori, Yoshihiro; Thammasirirak, Sompong

2014-08-01

Crocodylus siamensis hemoglobin was purified by a size exclusion chromatography, Sephacryl S-100 with buffer containing dithiothreitol. The purified Hb was dissociated to be two forms (α chain and β chain) which observed by SDS-PAGE, indicated that the C. siamensis Hb was an unpolymerized form. The unpolymerized Hb (composed of two α chains and two β chains) showed high oxygen affinity at 3.13 mmHg (P(50)) and 1.96 (n value), and a small Bohr effect (δH(+) = -0.29) at a pH of 6.9-8.4. Adenosine triphosphate did not affect the oxygenation properties, whereas bicarbonate ions strongly depressed oxygen affinity. Crude C. siamensis Hb solutions were showed high O(2) affinity at P(50) of 2.5 mmHg which may assure efficient utilization of the lung O(2) reserve during breath holding and diving. The purified Hbs were changed to cyanmethemoglobin forms prior crystallization. Rod- and plate-shaped crystals were obtained by the sitting-drop vapor-diffusion method at 5 °C using equal volumes of protein solution (37 mg/ml) and reservoir [10-13 % (w/v) PEG 4000, with 0.1 M Tris buffer in present of 0.2 M MgCl(2)·6H(2)O] solution at a pH of 7.0-8.5.

Identification of Bacillus anthracis by Using Monoclonal Antibody to Cell Wall Galactose-N-Acetylglucosamine Polysaccharide

DTIC Science & Technology

1990-02-01

which appear to be directed to an epitope associated with the galactose-N-acetyl-D- glucosamine polysaccharide. Both demonstrated specificity in their...liquid composed primarily of D-galactose and N-acetyl-D-glu - R medium (28) buffered with 50 mM Tris hydrochloride , pH cosamine (12, 13) (Gal-NAG...Ascites fluid (5 ml) was dialyzed (Cel-Line Associates, Inc., Newfield, N.J.). Suspensions against 20 mM Tris hydrochloride (pH 8.0) for 18 to 20 h, were

Chelatable trace zinc causes low, irreproducible KDAC8 activity.

PubMed

Toro, Tasha B; Edenfield, Samantha A; Hylton, Brandon J; Watt, Terry J

2018-01-01

Acetylation is an important regulatory mechanism in cells, and emphasis is being placed on identifying substrates and small molecule modulators of this post-translational modification. However, the reported in vitro activity of the lysine deacetylase KDAC8 is inconsistent across experimental setups, even with the same substrate, complicating progress in the field. We detected trace levels of zinc, a known inhibitor of KDAC8 when present in excess, even in high-quality buffer reagents, at concentrations that are sufficient to significantly inhibit the enzyme under common reaction conditions. We hypothesized that trace zinc in solution could account for the observed variability in KDAC8 activity. We demonstrate that addition of chelators, including BSA, EDTA, and citrate, and/or the use of a phosphate-based buffer instead of the more common tris-based buffer, eliminates the inhibition from low levels of zinc as well as the dependence of specific activity on enzyme concentration. This results in high KDAC8 activity that is consistent across buffer systems, even using low concentrations of enzyme. We report conditions that are suitable for several assays to increase both enzyme activity and reproducibility. Our results have significant implications for approaches used to identify substrates and small molecule modulators of KDAC8 and interpretation of existing data. Copyright © 2017 Elsevier Inc. All rights reserved.

Stimulated low-frequency Raman scattering in plant virus suspensions

NASA Astrophysics Data System (ADS)

Donchenko, E. K.; Karpova, O. V.; Kudryavtseva, A. D.; Pershin, S. M.; Savichev, V. I.; Strokov, M. A.; Tcherniega, N. V.; Zemskov, K. I.

2017-11-01

The study deals with laser pulse interaction with plant viruses: we investigated tobacco mosaic virus (TMV) and two types of potato viruses (PVX and PVA) in Tris-HCl pH7.5 buffer and in water. We used 20 ns ruby laser pulses for excitation. We employed Fabry-Pérot interferometers to record spectra of the light passing through the sample and reflected from it. For TMV and PVX in Tris-HCl pH7.5 buffer, same as for PVA in water, we observed additional spectral lines corresponding to the stimulated low-frequency Raman scattering (SLFRS). We believe we were the first to measure SLFRS frequency shifts, conversion efficiency and threshold. High conversion efficiency of the scattered light is evidence of laser pulses efficiently exciting gigahertz vibrations in viruses. SLFRS can be used to identify and affect biological nanoparticles.

Identification of a silver binding protein associated with the cytological silver staining of actively transcribing nucleolar regions.

PubMed

Hubbell, H R; Rothblum, L I; Hsu, T C

1979-10-01

Nucleoli isolated from Novikoff hepatoma cells were stained with AgNO3 to demonstrate the typical staining of active ribosomal cistrons. Pre-treatment of the nucleoli with 80 mM Tris-HCl (pH 7.5) -- 2.0 M NaCl did not interfere with silver staining. Treatment of the nucleoli with 80 mM Tris-HCl (pH 7.5) -- 0.15 M NaCl did, however, eliminate silver binding. Serial extraction of nucleoli with 2.0 M NaCl buffer followed by 0.15 M NaCl buffer also abolished silver staining. Analysis of the supernatant fraction of these extracts by polyacrylamide gel electrophoresis indicates that, although more than one nucleolar protein can bind silver, only one protein is associated with the staining of active ribosomal cistrons.

A rapid procedure for measurement of the free testosterone fraction in human plasma using the centria radioimmunoassay centrifugal analyzer.

PubMed

Schwarz, S; Boyd, J

1981-01-01

Following the incubation of plasma with a tracer amount of tritiated testosterone, the reaction mixture is separated into a sex hormone-binding globulin bound and an unbound fraction of radioligand using DEAE-cellulose columns placed in the incubator-separator module of the Centria radioimmunoassay centrifugal analyzer. Neural Tris-buffer elutes unbound steroid from the matrix, while acidic Tris-buffer can remove the protein-bound fraction in a subsequent step. Complementary and thus qualitatively equal results are obtained when counting either eluate. Comparison of this technique with an ammonium sulfate precipitation method showed high correlation. Free testosterone indices as determined by the Centria modification in a number of prepuberal children, normal men and women, as well as pregnant and hirsute women similar to those previously reported.

Separation of silver nanoparticles by hollow fiber flow field-flow fractionation: Addition of tannic acid into carrier liquid as a modifier.

PubMed

Saenmuangchin, Rattaporn; Mettakoonpitak, Jaruwan; Shiowatana, Juwadee; Siripinyanond, Atitaya

2015-10-09

A homemade hollow fiber flow-field fractionation (Hf-FlFFF) coupled with inductively coupled plasma mass spectrometry (ICP-MS) was set-up for silver nanoparticles (AgNPs) separation by using polysulfone hollow fiber membrane (30,000 MW cutoff) as a separation channel. Tannic acid and citrate stabilized AgNPs were synthesized and introduced into Hf-FlFFF. The effects of carrier liquid and stabilizing agent on retention behavior of AgNPs were investigated. Different elution behaviors were observed as follows: with 0.02% (w/v) FL-70, all of AgNPs were eluted from Hf-FlFFF but differences in retention behaviors were observed for AgNPs with tannic acid and citrate stabilizing agents; and with 30mM TRIS buffer, only tannic acid stabilized AgNPs were eluted from Hf-FlFFF, whereas citrate stabilized AgNPs were not eluted. In this work, tannic acid addition into carrier liquid was proposed to modify the surface of AgNPs and the surface of the membrane, and thereby adjusting the retention behaviors of AgNPs. Various concentrations of tannic acid were added into FL-70 and TRIS buffer. With the use of 0.1mM tannic acid in 30mM TRIS buffer as the carrier liquid, retention behaviors of both tannic acid stabilized- and citrate stabilized-AgNPs were similar and with similar fractionation recovery. Copyright © 2015 Elsevier B.V. All rights reserved.

Technical Evaluation of Sample-Processing, Collection, and Preservation Methods

DTIC Science & Technology

2014-07-01

For the Gram-positive organism, B. atrophaeus var. globigii (Unified Culture Collection [ UCC ] designation: BACI051) was selected as a surrogate for...the well-known biothreat agent Bacillus anthracis. For the Gram-negative organism, Y. pestis CO92 (pgm–) ( UCC designation: YERS059) was selected...Diagnostics device) TAMRA tetramethylrhodamine TE buffer tris-ethylenediaminetetraacetic acid buffer UCC Unified Culture Collection USG U.S. Government

The effect of CO2 and non-CO2-generating buffers on cerebral acidosis after cardiac arrest: A 31P NMR study.

PubMed

Rosenberg, J M; Martin, G B; Paradis, N A; Nowak, R M; Walton, D; Appleton, T J; Welch, K M

1989-04-01

There is controversy regarding the use of alkalinizing agents during reperfusion after cardiac arrest. The potential deleterious effects of sodium bicarbonate (bicarb) administration, including paradoxic cerebral acidosis, have led to the search for alternative agents. Tromethamine (tris) is a non-CO2-generating buffer that has been proposed for use during cardiopulmonary resuscitation. The purpose of this experiment was to compare the ability of tris with bicarb to correct brain pH (pH B) during reperfusion after a 12-minute cardiac arrest. Adult mongrel dogs were instrumented and placed in the bore of a Bruker Biospec 1.89 tesla superconducting magnet system. Ventricular fibrillation was induced; after 12 minutes, cardiopulmonary bypass was initiated and maintained for two hours with minimum flows of 80 mL/kg/min. Bicarb (n = 5) or tris (n = 5) were administered to correct arterial pH as rapidly as possible. 31P NMR spectra were obtained at baseline and throughout ischemia and reperfusion. The pH B was determined with the inorganic phosphate relative to the phosphocreatine resonance signal shift. Profile analysis indicates a difference between groups (P less than .02) related to an initial delay in pH B correction in the tris group. By 48 minutes of reperfusion, pH B did not differ between the groups. Moreover, there was no evidence of paradoxic cerebral acidosis in the bicarb group. Although tris corrects blood pH as quickly as bicarb, it is less effective in correcting pH B. Absence of paradoxic acidosis may be caused by efficient elimination of CO2 by cardiopulmonary bypass.

Apparent electric charge of protein molecules. Human thyroxine - binding proteins.

PubMed

Hocman, G; Sadlon, J

1977-01-01

1. By comparison of electrophoretic mobilities of two different charged particles under the same conditions the net elementary electrostatic charge of one particle could be calculated when the charge of the other is known. 2. The electrophoretic mobility of human thyroxine - binding globulin does not depend upon the concentration of Tris - HCl buffer in the range 0.05 to 0.20 molar. The value of this mobility is 0.078 and 0.083 cm2 vol(-1) hour(-1) at pH 7.0 and 8.6, respectively. 3. The net elementary electrostatic charge of the human thyroxine - binding globulin appears to be approximately 22 negative elementary electrostatic units in mild alkaline solutions.

Bio resorbability of the modified hydroxyapatite in Tris-HCL buffer

NASA Astrophysics Data System (ADS)

Golovanova, O. A.; Izmailov, R. R.; Ghyngazov, S. A.

2016-02-01

The solubility of carbonated hydroxyapatite powders and granulated carbonated hydroxyapatite produced from the synovial biofluid model solution has been studied. The kinetic characteristics of dissolution were determined. It was found that the solubility of carbonated hydroxyapatite is higher as compared to that of hydroxyapatite. The impact of the organic matrix on the rate of sample dissolution was revealed. For HA-gelatin composites, as the gelatin concentration grows, the dissolution rate becomes greater, and a sample of 6.0 g / L concentration has higher resorbability. The results of the research can be used to study the kinetics of dissolution and the biocompatibility of ceramic materials for medicine, namely for reconstructive surgery, dentistry, and development of drug delivery systems.

76 FR 53451 - 2-(Hydroxymethyl)-2-nitro-1,3-propanediol (Tris Nitro); Amendments To Terminate Uses for Certain...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-26

.../ polymer emulsions; Specialty industrial products. 464-658 Tris Nitro \\TM\\ Brand of The Dow Chemical... emulsions; Specialty nitromethane. industrial products. 464-663 Tris Nitro\\TM\\ Brand of The Dow Chemical Company Use in paints, emulsions and 50% Aqueous Tris thickener solutions; Use in (hydroxymethyl...

Influence of Ca2+ on the mechanosensitivity of the hair cells in the lateral line organs of Necturus maculosus.

PubMed

Jørgensen, F

1983-08-01

The degree of synchronization (DOS) between the afferent spike activity from one stitch of the lateral line of Necturus maculosus (in vivo) and the mechanical stimulation of one neuromast of the same stitch was measured under different circumstances. The DOS was found to be independent of changes in the concentration of monovalent cations (Na+, K+ and choline+) in the bulk solution at high Ca concentration (1 mM). DOS was also independent of the Ca concentration in the range 1 mM-1 microM in Tris-HCl buffer, but was markedly reduced at Ca = 10 microM in MOPS-KOH buffer. The reduced DOS, however, could be restored by addition of 10-20 mM KCl. 5 mM of 4-aminopyridine did not influence the DOS at high Ca concentration, but completely reduced DOS at Ca = 10 microM. D600 (a methoxy derivative of verapamil) decreased DOS both at high and low Ca concentration.

Comparison of Four Nuclear Isolation Buffers for Plant DNA Flow Cytometry

PubMed Central

LOUREIRO, JOÃO; RODRIGUEZ, ELEAZAR; DOLEŽEL, JAROSLAV; SANTOS, CONCEIÇÃO

2006-01-01

• Background and Aims DNA flow cytometry requires preparation of suspensions of intact nuclei, which are stained using a DNA-specific fluorochrome prior to analysis. Various buffer formulas were developed to preserve nuclear integrity, protect DNA from degradation and facilitate its stoichiometric staining. Although nuclear isolation buffers differ considerably in chemical composition, no systematic comparison of their performance has been made until now. This knowledge is required to select the appropriate buffer for a given species and tissue. • Methods Four common lysis buffers (Galbraith's, LB01, Otto's and Tris.MgCl2) were used to prepare samples from leaf tissues of seven plant species (Sedum burrito, Oxalis pes-caprae, Lycopersicon esculentum, Celtis australis, Pisum sativum, Festuca rothmaleri and Vicia faba). The species were selected to cover a wide range of genome sizes (1·30–26·90 pg per 2C DNA) and a variety of leaf tissue types. The following parameters were assessed: forward (FS) and side (SS) light scatters, fluorescence of propidium iodide-stained nuclei, coefficient of variation of DNA peaks, presence of debris background and the number of nuclei released from sample tissue. The experiments were performed independently by two operators and repeated on three different days. • Key Results Clear differences among buffers were observed. With the exception of O. pes-caprae, any buffer provided acceptable results for all species. LB01 and Otto's were generally the best buffers, with Otto's buffer providing better results in species with low DNA content. Galbraith's buffer led to satisfactory results and Tris.MgCl2 was generally the worst, although it yielded the best histograms in C. australis. A combined analysis of FS and SS provided a ‘fingerprint’ for each buffer. The variation between days was more significant than the variation between operators. • Conclusions Each lysis buffer tested responded to a specific problem differently and none of the buffers worked best with all species. These results expand our knowledge on nuclear isolation buffers and will facilitate selection of the most appropriate buffer depending on species, tissue type and the presence of cytosolic compounds interfering with DNA staining. PMID:16820407

Studies on the intracellular Ca2+ concentration of thawed dog spermatozoa: influence of Equex from different sources, two thawing diluents and post-thaw incubation in capacitating conditions.

PubMed

Peña, A I; López-Lugilde, L; Barrio, M; Becerra, J J; Quintela, L A; Herradón, P G

2003-02-01

The addition of 0.5% (v/v) of Equex STM Paste (Nova Chemical Sales, Scituate Inc., MA, USA), whose active ingredient is sodium dodecyl sulphate (SDS), to a Tris-egg yolk extender was demonstrated to improve the longevity of frozen-thawed dog spermatozoa during in vitro incubation at 38 degrees C. The aim of the first experiment was to compare the effects of two SDS-containing compounds, Equex STM Paste and Equex Pasta (Minitüb, Tiefenbach, Germany), when added to a Tris-egg yolk based extender, on the post-thaw longevity of dog spermatozoa, as well as on the intracellular Ca2+ concentration of spermatozoa, during post-thaw incubation at 38 degrees C. The post-thaw sperm survival and longevity, as well as the quality of the sperm movement, were significantly better when using Equex STM Paste. Such prolonged sperm longevity, however, was associated to a higher intracellular Ca2+ concentration in a large subpopulation of the live spermatozoa. A second experiment was aimed to evaluate the effects of sperm dilution immediately post-thaw with a Tris buffer containing glucose or fructose. The two Tris buffers were no different for any of the sperm parameters studied. The aim of a third experiment was to evaluate the sperm longevity, motility patterns and intracellular Ca2+ concentration of cryopreserved dog spermatozoa during post-thaw incubation in capacitating conditions [canine capacitating medium (CCM) with or without 5 microg/ml of heparin]. Heparin had no significant effects on any of the sperm parameters evaluated. During the first 8 h of incubation, the majority of the live spermatozoa had a high intracellular Ca2+ content. However, after 8-10 h of incubation, it had significantly declined. The highest proportion of fast motile sperm, and the highest curvilinear velocity, average path velocity and amplitude of lateral head displacement for the total motile sperm were observed during the 2-4-h incubation period. It was concluded that: (a) the addition of 0.5% (v/v) of Equex STM Paste to a Tris-egg yolk based extender significantly improved the post-thaw longevity of dog spermatozoa, but the same concentration of Equex Pasta had no significant beneficial effects; (b) sperm dilution after thawing with a Tris buffer containing glucose or fructose made no difference in post-thaw sperm longevity; (c) the addition of 5 microg/ml of heparin to CCM had no significant capacitating effects on frozen-thawed dog spermatozoa.

Regulating NETosis: Increasing pH Promotes NADPH Oxidase-Dependent NETosis

PubMed Central

Khan, Meraj A.; Philip, Lijy M.; Cheung, Guillaume; Vadakepeedika, Shawn; Grasemann, Hartmut; Sweezey, Neil; Palaniyar, Nades

2018-01-01

Neutrophils migrating from the blood (pH 7.35–7.45) into the surrounding tissues encounter changes in extracellular pH (pHe) conditions. Upon activation of NADPH oxidase 2 (Nox), neutrophils generate large amounts of H+ ions reducing the intracellular pH (pHi). Nevertheless, how extracellular pH regulates neutrophil extracellular trap (NET) formation (NETosis) is not clearly established. We hypothesized that increasing pH increases Nox-mediated production of reactive oxygen species (ROS) and neutrophil protease activity, stimulating NETosis. Here, we found that raising pHe (ranging from 6.6 to 7.8; every 0.2 units) increased pHi of both activated and resting neutrophils within 10–20 min (Seminaphtharhodafluor dual fluorescence measurements). Since Nox activity generates H+ ions, pHi is lower in neutrophils that are activated compared to resting. We also found that higher pH stimulated Nox-dependent ROS production (R123 generation; flow cytometry, plate reader assay, and imaging) during spontaneous and phorbol myristate acetate-induced NETosis (Sytox Green assays, immunoconfocal microscopy, and quantifying NETs). In neutrophils that are activated and not resting, higher pH stimulated histone H4 cleavage (Western blots) and NETosis. Raising pH increased Escherichia coli lipopolysaccharide-, Pseudomonas aeruginosa (Gram-negative)-, and Staphylococcus aureus (Gram-positive)-induced NETosis. Thus, higher pHe promoted Nox-dependent ROS production, protease activity, and NETosis; lower pH has the opposite effect. These studies provided mechanistic steps of pHe-mediated regulation of Nox-dependent NETosis. Raising pH either by sodium bicarbonate or Tris base (clinically known as Tris hydroxymethyl aminomethane, tromethamine, or THAM) increases NETosis. Each Tris molecule can bind 3H+ ions, whereas each bicarbonate HCO3− ion binds 1H+ ion. Therefore, the amount of Tris solution required to cause the same increase in pH level is less than that of equimolar bicarbonate solution. For that reason, regulating NETosis by pH with specific buffers such as THAM could be more effective than bicarbonate in managing NET-related diseases. PMID:29487850

DNA adsorption onto glass surfaces

NASA Astrophysics Data System (ADS)

Carlson, Krista Lynn

Streaming potential measurements were performed on microspheres of silica, lime silicate (SLS) and calcium aluminate (CA) glasses containing silica and iron oxide (CASi and CAFe). The silicate based glasses exhibited acidic surfaces with isoelectric points (IEP) around a pH of 3 while the calcium aluminates displayed more basic surfaces with IEP ranging from 8--9.5. The surface of the calcium aluminate microspheres containing silica reacted with the background electrolyte, altering the measured zeta potential values and inhibiting electrolyte flow past the sample at ˜ pH 4 due to formation of a solid plug. DNA adsorption experiments were performed using the microspheres and a commercially available silicate based DNA isolation filter using a known quantity of DNA suspended in a chaotropic agent free 0.35 wt% Tris(hydroxymethyl)aminomethane (Tris) buffer solution. The microspheres and commercial filter were also used to isolate DNA from macrophage cells in the presence of chaotropic agents. UV absorbance at ˜260 nm and gel electrophoresis were used to quantify the amount and size of the DNA strands that adsorbed to the microsphere surfaces. In both experiments, the 43--106 microm CAFe microspheres adsorbed the largest quantity of DNA. However, the 43--106 microm SLS microspheres isolated more DNA from the cells than the <43 microm CAFe microspheres, indicating that microsphere size contributes to isolation ability. The UV absorbance of DNA at ˜260 nm was slightly altered due to the dissolution of the calcium aluminate glasses during the adsorption process. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) determined that calcium and aluminum ions leached from the CA and CAFe microsphere surfaces during these experiments. Circular dichroism (CD) spectroscopy showed that the leached ions had no effect on the conformation of the DNA, and therefore would not be expected to interfere in downstream applications such as DNA replication. The 0.35 wt% Tris solution completely inhibited the formation of the hydrated crystalline layer that develops when the calcium aluminate glassess are incubated in deionized water. A Tris concentration of 0.24 wt% allowed for the formation of both hexagonal and cubic hydrates, however they were severely distorted and present in low amounts such that they were undectable by XRD.

Phosphate-based glass fiber vs. bulk glass: Change in fiber optical response to probe in vitro glass reactivity.

PubMed

Massera, J; Ahmed, I; Petit, L; Aallos, V; Hupa, L

2014-04-01

This paper investigates the effect of fiber drawing on the thermal and structural properties as well as on the glass reactivity of a phosphate glass in tris(hydroxymethyl)aminomethane-buffered (TRIS) solution and simulated body fluid (SBF). The changes induced in the thermal properties suggest that the fiber drawing process leads to a weakening and probable re-orientation of the POP bonds. Whereas the fiber drawing did not significantly impact the release of P and Ca, an increase in the release of Na into the solution was noticed. This was probably due to small structural reorientations occurring during the fiber drawing process and to a slight diffusion of Na to the fiber surface. Both the powders from the bulk and the glass fibers formed a Ca-P surface layer when immersed in SBF and TRIS. The layer thickness was higher in the calcium and phosphate supersaturated SBF than in TRIS. This paper for the first time presents the in vitro reactivity and optical response of a phosphate-based bioactive glass (PBG) fiber when immersed in SBF. The light intensity remained constant for the first 48h after which a decrease with three distinct slopes was observed: the first decrease between 48 and 200h of immersion could be correlated to the formation of the Ca-P layer at the fiber surface. After this a faster decrease in light transmission was observed from 200 to ~425h in SBF. SEM analysis suggested that after 200h, the surface of the fiber was fully covered by a thin Ca-P layer which is likely to scatter light. For immersion times longer than ~425h, the thickness of the Ca-P layer increased and thus acted as a barrier to the dissolution process limiting further reduction in light transmission. The tracking of light transmission through the PBG fiber allowed monitoring of the fiber dissolution in vitro. These results are essential in developing new bioactive fiber sensors that can be used to monitor bioresponse in situ. Copyright © 2014 Elsevier B.V. All rights reserved.

Regulating NETosis: Increasing pH Promotes NADPH Oxidase-Dependent NETosis.

PubMed

Khan, Meraj A; Philip, Lijy M; Cheung, Guillaume; Vadakepeedika, Shawn; Grasemann, Hartmut; Sweezey, Neil; Palaniyar, Nades

2018-01-01

Neutrophils migrating from the blood (pH 7.35-7.45) into the surrounding tissues encounter changes in extracellular pH (pH e ) conditions. Upon activation of NADPH oxidase 2 (Nox), neutrophils generate large amounts of H + ions reducing the intracellular pH (pH i ). Nevertheless, how extracellular pH regulates neutrophil extracellular trap (NET) formation (NETosis) is not clearly established. We hypothesized that increasing pH increases Nox-mediated production of reactive oxygen species (ROS) and neutrophil protease activity, stimulating NETosis. Here, we found that raising pH e (ranging from 6.6 to 7.8; every 0.2 units) increased pH i of both activated and resting neutrophils within 10-20 min (Seminaphtharhodafluor dual fluorescence measurements). Since Nox activity generates H + ions, pH i is lower in neutrophils that are activated compared to resting. We also found that higher pH stimulated Nox-dependent ROS production (R123 generation; flow cytometry, plate reader assay, and imaging) during spontaneous and phorbol myristate acetate-induced NETosis (Sytox Green assays, immunoconfocal microscopy, and quantifying NETs). In neutrophils that are activated and not resting, higher pH stimulated histone H4 cleavage (Western blots) and NETosis. Raising pH increased Escherichia coli lipopolysaccharide-, Pseudomonas aeruginosa (Gram-negative)-, and Staphylococcus aureus (Gram-positive)-induced NETosis. Thus, higher pH e promoted Nox-dependent ROS production, protease activity, and NETosis; lower pH has the opposite effect. These studies provided mechanistic steps of pH e -mediated regulation of Nox-dependent NETosis. Raising pH either by sodium bicarbonate or Tris base (clinically known as Tris hydroxymethyl aminomethane, tromethamine, or THAM) increases NETosis. Each Tris molecule can bind 3H + ions, whereas each bicarbonate HCO3 - ion binds 1H + ion. Therefore, the amount of Tris solution required to cause the same increase in pH level is less than that of equimolar bicarbonate solution. For that reason, regulating NETosis by pH with specific buffers such as THAM could be more effective than bicarbonate in managing NET-related diseases.

Nonaqueous capillary electrophoresis with indirect electrochemical detection.

PubMed

Matysik, Frank-Michael; Marggraf, Daniela; Gläser, Petra; Broekaert, José A C

2002-11-01

Nonaqueous capillary electrophoresis (NACE) which makes use of organic solvents in place of conventional aqueous electrophoresis buffers is gaining increasing importance among modern separation techniques. Recently, it has been shown that amperometric detection in conjunction with acetonitrile-based NACE offers an extended accessible potential range and an enhanced long-term stability of the amperometric responses generated at solid electrodes. The present contribution takes advantage of the latter aspect to develop reliable systems for NACE with indirect electrochemical detection (IED). In this context, several compounds such as (ferrocenylmethyl)trimethylammonium perchlorate, tris(1,10-phenanthroline)cobalt(III) perchlorate and bis(1,4,7-triazacyclononane)nickel(II) perchlorate were studied regarding their suitability to act as electroactive buffer additives for IED in NACE. The performance characteristics for the respective buffer systems were evaluated. Tetraalkylammonium perchlorates served as model compounds for the optimization of the NACE-IED system. Target analytes choline and acetylcholine could easily be separated and determined by means of NACE-IED. In the case of a buffer system containing 10(-4) M tris(1,10-phenanthroline)cobalt(III) perchlorate the limits of detection were 2.5 x 10(-7) M and 4.6 x 10(-7) M for choline and acetylcholine, respectively. With the elaborated analytical procedure choline could be determined in pharmaceutical preparations.

Glass corrosion in natural environments

NASA Technical Reports Server (NTRS)

Thorpe, Arthur N.; Barkatt, Aaron

1992-01-01

Experiments carried out during the progress period are summarized. Experiments carried out involving glass samples exposed to solutions of Tris have shown the appearance of 'spikes' upon monitoring glass dissolution as a function of time. The periodic 'spikes' observed in Tris-based media were interpreted in terms of cracking due to excessive stress in the surface region of the glass. Studies of the interactions of silicate glasses with metal ions in buffered media were extended to systems containing Al. Caps buffer was used to establish the pH. The procedures used are described and the results are given. Preliminary studies were initiated as to the feasibility of adding a slowly dissolving solid compound of the additive to the glass-water system to maintain a supply of dissolved additive. It appears that several magnesium compounds have a suitable combination of solubility and affinity towards silicate glass surfaces to have a pronounced retarding effect on the extraction of uranium from the glass. These preliminary findings raise the possibility that introducing a magnesium source into geologic repositories for nuclear waste glass in the form of a sparingly soluble Mg-based backfill material may cause a substantial reduction in the extent of long-term glass corrosion. The studies described also provide mechanistic understanding of the roles of various metal solutes in the leachant. Such understanding forms the basis for developing long-term predictions of nuclear waste glass durability under repository conditions. From what is known about natural highly reduced glasses such as tektites, it is clear that iron is dissolved as ferrous iron with little or no ferric iron. The reducing conditions were high enough to cause metallic iron to exsolve out of the glass in the form of submicroscopic spherules. As the nuclear waste glass is much less reduced, a study was initiated on other natural glasses in addition to the nuclear waste glass. Extensive measurements were carried out on these glasses in order to characterize their magnetic properties. Results of these studies are described.

In Vitro and in Vivo Evaluation of Native Glucagon and Glucagon Analog (MAR-D28) during Aging: Lack of Cytotoxicity and Preservation of Hyperglycemic Effect

PubMed Central

Ward, W Kenneth; Massoud, Ryan G; Szybala, Cory J; Engle, Julia M; El Youssef, Joseph; Carroll, Julie M; Roberts, Charles T; DiMarchi, Richard D

2010-01-01

Background For automated prevention of hypoglycemia, there is a need for glucagon (or an analog) to be sufficiently stable so that it can be indwelled in a portable pump for at least 3 days. However, under some conditions, solutions of glucagon can form amyloid fibrils. Currently, the usage instructions for commercially available glucagon allow only for its immediate use. Methods In NIH 3T3 fibroblasts, we tested amyloid formation and cytotoxicity of solutions of native glucagon and the glucagon analog MAR-D28 after aging under different conditions for 5 days. In addition, aged native glucagon was subjected to size-exclusion chromatography (SEC). We also studied whether subcutaneous aged Novo Nordisk GlucaGen® would have normal bioactivity in octreotide-treated, anesthetized, nondiabetic pigs. Results We found no evidence of cytotoxicity from native glucagon or MAR-D28 (up to 2.5 mg/ml) at a pH of 10 in a glycine solvent. We found a mild cytotoxicity for both compounds in Tris buffer at pH 8.5. A high concentration of the commercial glucagon preparation (GlucaGen) caused marked cytotoxicity, but low pH and/or a high osmolarity probably accounted primarily for this effect. With SEC, the decline in monomeric glucagon over time was much lower when aged in glycine (pH 10) than when aged in Tris (pH 8.5) or in citrate (pH 3). Congo red staining for amyloid was very low with the glycine preparation (pH 10). In the pig studies, the hyperglycemic effect of commercially available glucagon was preserved despite aging conditions associated with marked amyloid formation. Conclusions Under certain conditions, aqueous solutions of glucagon and MAR-D28 are stable for at least 5 days and are thus very likely to be safe in mammals. Glycine buffer at a pH of 10 appears to be optimal for avoiding cytotoxicity and amyloid fibril formation. PMID:21129325

Salt-Dependent DNA-DNA Spacings in Intact Bacteriophage lambda Reflect Relative Importance of DNA Self-Repulsion and Bending Energies

DOE Office of Scientific and Technical Information (OSTI.GOV)

X Qiu; D Rau; V Parsegian

2011-12-31

Using solution synchrotron x-ray scattering, we measure the variation of DNA-DNA d spacings in bacteriophage {lambda} with mono-, di-, and polyvalent salt concentrations, for wild-type [48.5 x 10{sup 3} base pairs (bp)] and short-genome-mutant (37.8 kbp) strains. From the decrease in d spacings with increasing salt, we deduce the relative contributions of DNA self-repulsion and bending to the energetics of packaged phage genomes. We quantify the DNA-DNA interaction energies within the intact phage by combining the measured d spacings in the capsid with measurements of osmotic pressure in DNA assemblies under the same salt conditions in bulk solution. In themore » commonly used Tris-Mg buffer, the DNA-DNA interaction energies inside the phage capsids are shown to be about 1 kT/bp, an order of magnitude larger than the bending energies.« less

Evaluation of the stability of uranyl peroxo-carbonato complex ions in carbonate media at different temperatures.

PubMed

Kim, Kwang-Wook; Lee, Keun-Young; Chung, Dong-Yong; Lee, Eil-Hee; Moon, Jei-Kwon; Shin, Dong-Woo

2012-09-30

This work studied the stability of peroxide in uranyl peroxo carbonato complex ions in a carbonate solution with hydrogen peroxide using absorption and Raman spectroscopies, and evaluated the temperature dependence of the decomposition characteristics of uranyl peroxo carbonato complex ions in the solution. The uranyl peroxo carbonato complex ions self-decomposed more rapidly into uranyl tris-carbonato complex ions in higher temperature carbonate solutions. The concentration of peroxide in the solution without free hydrogen peroxide represents the concentration of uranyl peroxo carbonato complex ions in a mixture of uranyl peroxo carbonato complex and uranyl tris-carbonato complex ions. The self-decomposition of the uranyl peroxo carbonato complex ions was a first order reaction, and its activation energy was evaluated to be 7.144×10(3) J mol(-1). The precipitation of sodium uranium oxide hydroxide occurred when the amount of uranyl tris-carbonato complex ions generated from the decomposition of the uranyl peroxo carbonato complex ions exceeded the solubility of uranyl tris-carbonato ions in the solution at the solution temperature. Copyright © 2012 Elsevier B.V. All rights reserved.

Partial Purification and Characterization of Restriction Endonuclease from Neisseria meningitidis.

DTIC Science & Technology

1983-12-01

by centrifugation at 15,000 x g for 10 min. Preparation of Cell-Free Extract The cell pellet was suspended in 10 mL of Tris-HCI buffer pH 7.6 (Tris, 20...free extract (CFE) was obtained by centrifugation at 100,000 x g for I h. To the CFE, glycerol was added to a final concentration of 10% and stored at... extract obtained from N. meningilidis when incubated with A DNA and analyzed by agarose gel electrophoresis did not give a clean fragmentation pattern

Effect of Tris-acetate buffer on endotoxin removal from human-like collagen used biomaterials.

PubMed

Zhang, Huizhi; Fan, Daidi; Deng, Jianjun; Zhu, Chenghui; Hui, Junfeng; Ma, Xiaoxuan

2014-09-01

Protein preparation, which has active ingredients designated for the use of biomaterials and therapeutical protein, is obtained by genetic engineering, but products of genetic engineering are often contaminated by endotoxins. Because endotoxin is a ubiquitous and potent proinflammatory agent, endotoxin removal or depletion from protein is essential for researching any biomaterials. In this study, we have used Tris-acetate (TA) buffer of neutral pH value to evaluate endotoxins absorbed on the Pierce high-capacity endotoxin removal resin. The effects of TA buffer on pH, ionic strength, incubation time as well as human-like collagen (HLC) concentration on eliminating endotoxins are investigated. In the present experiments, we design an optimal method for TA buffer to remove endotoxin from recombinant collagen and use a chromogenic tachypleus amebocyte lysate (TAL) test kit to measure the endotoxin level of HLC. The present results show that, the endotoxins of HLC is dropped to 8.3EU/ml at 25 mM TA buffer (pH7.8) with 150 mM NaCl when setting incubation time at 6h, and HLC recovery is about 96%. Under this experimental condition, it is proved to exhibit high efficiencies of both endotoxin removal and collagen recovery. The structure of treated HLC was explored by Transmission Electron Microscopy (TEM), demonstrating that the property and structure of HLC treated by TA buffer are maintained. Compared to the most widely used endotoxin removal method, Triton X-114 extraction, using TA buffer can obtain the non-toxic HLC without extra treatment for removing the toxic substances in Triton X-114. In addition, the present study aims at establishing a foundation for further work in laboratory animal science and providing a foundation for medical grade biomaterials. Copyright © 2014 Elsevier B.V. All rights reserved.

Efficacy of a novel mucolytic agent on pseudomyxoma peritonei mucin, with potential for treatment through peritoneal catheters

PubMed Central

Akhter, Javed; Pillai, Krishna; Chua, Terence C; Alzarin, Naeef; Morris, David Lawson

2014-01-01

Compared to current treatment for pseudomyxoma peritonei (PMP), the extraction of solubilised mucin through peritoneal catheter can be minimally invasive. However, mucin has variable appearance that may influence mucolysis. Hence, we investigated the mucolysis of 36 mucin samples with a novel agent. Using visual inspection and hardness index, PMP mucin was classified into three grades. The mucin pathological category was identified from patient record. Subsequently, the dissolution of the samples was tested. For in vitro, 1 g of mucin was treated to the mucolytic agent in 10 ml TRIS buffer at 37 deg. Celsius for 3 hours, with weighing of residual mucin. Control treatment was similar but received TRIS buffer. For in vivo, 2 g of implanted intra-peritoneal mucin in nude rats was treated to mucolytic (2 X 500 ul/24 hr, over 48 hours, plus another treatment before sacrifice at 56 hours, with weighing of residual mucin. Controls were treated but only with TRIS buffer. Six animals were used for each mucin grade (3 mucolytic treated & and 3 controls). Grades of mucin were soft mucin (62%), semi hard (20%) and hard mucin (18%). Diffuse peritoneal adenomucinosis had 50% of soft mucin and peritoneal mucinous carcinoma had 11% (P = 0.0382). In vitro and in vivo absolute disintegration was 100% for soft, 57.38% and 48.67% for semi hard, 50% and 28.67% for hard mucin. Majority of mucin were soft with complete disintegration, the rest showed variable disintegration, suggesting that the mucolytic has potential for treating PMP. PMID:25232491

Mechanical loading of bovine pericardium accelerates enzymatic degradation.

PubMed

Ellsmere, J C; Khanna, R A; Lee, J M

1999-06-01

Bioprosthetic heart valves fail as the result of two simultaneous processes: structural deterioration and calcification. Leaflet deterioration and perforation have been correlated with regions of highest stress in the tissue. The failures have long been assumed to be due to simple mechanical fatigue of the collagen fibre architecture; however, we have hypothesized that local stresses-and particularly dynamic stresses-accelerate local proteolysis, leading to tissue failure. This study addresses that hypothesis. Using a novel, custom-built microtensile culture system, strips of bovine pericardium were subjected to static and dynamic loads while being exposed to solutions of microbial collagenase or trypsin (a non-specific proteolytic enzyme). The time to extend to 30% strain (defined here as time to failure) was recorded. After failure, the percentage of collagen solubilized was calculated based on the amount of hydroxyproline present in solution. All data were analyzed by analysis of variance (ANOVA). In collagenase, exposure to static load significantly decreased the time to failure (P < 0.002) due to increased mean rate of collagen solubilization. Importantly, specimens exposed to collagenase and dynamic load failed faster than those exposed to collagenase under the same average static load (P = 0.02). In trypsin, by contrast, static load never led to failure and produced only minimal degradation. Under dynamic load, however, specimens exposed to collagenase, trypsin, and even Tris/CaCl2 buffer solution, all failed. Only samples exposed to Hanks' physiological solution did not fail. Failure of the specimens exposed to trypsin and Tris/CaCl2 suggests that the non-collagenous components and the calcium-dependent proteolytic enzymes present in pericardial tissue may play roles in the pathogenesis of bioprosthetic heart valve degeneration.

DNA polymerases in the rat pituitary gland. Effect of oestrogens and sulpiride.

PubMed

Jahn, G A; Kalbermann, L E; Machiavelli, G; Szijan, I; Burdman, J A

1980-06-01

Changes in the activity of DNA polymerase and [3H]thymidine incorporation into the DNA of the anterior pituitary gland were studied in oestrogenized male and pregnant rats. The activities of DNA polymerases alpha and beta, extracted in Tris--HCl or in sodium phosphate buffer were characterized according to their optimum pH and sensitivity to N-ethyl-maleimide. In the Tris-soluble fraction DNA polymerase activity is almost exclusively alpha, while in the phosphate soluble fraction it is a mixture of alpha and beta. The administration of oestrogens to male rats increases [3H]thymidine incorporation and enhances the activity of DNA polymerases in the Tris-soluble fraction, while the activity of the phosphate-soluble enzyme does not change. Sulpiride administration results in a further increment of [3H]thymidine incorporation and of DNA polymerase activity in the Tris-soluble fraction. In pregnant rats sulpiride also produces an increment of DNA polymerase activity only in the Tris-soluble fraction. Thus, the activity of the Tris-soluble fraction from APG behaves as DNA polymerase alpha. This activity changes in parallel with [3H]thymidine incorporation into DNA which is an indication of cell proliferation in the gland. This is discussed with respect to a negative feedback mechanism between intracellular prolactin concentration and DNA synthesis in the APG.

A biocompatible synthesis of gold nanoparticles by Tris(hydroxymethyl)aminomethane

NASA Astrophysics Data System (ADS)

Chen, Feng; Wang, Yanwei; Ma, Jun; Yang, Guangcan

2014-05-01

Gold nanoparticles' novel properties are widely realized in catalysis, plasmonics, electronics, and biomedical applications. For biomedical application, one challenge is to find a non-toxic chemical and/or physical method of functionalizing gold nanoparticles with biomolecular compounds that can promote efficient binding, clearance, and biocompatibility and to assess their safety to other biological systems and their long-term effects on human health and reproduction. In the present study, we describe a new method by using Tris(hydroxymethyl)aminomethane (Tris), a widely used buffer solvent of nucleic acid and proteins, as the reducing agent for synthesizing gold nanoparticles by one step. It is found that Tris carries out the reduction reactions in relatively mild conditions for biomacromolecules. Particularly, it can be used to modify the DNA during the process of preparation of gold nanoparticles. The morphology and size distribution of gold nanoparticles are consistent and were confirmed by many different approaches including dynamic light scattering (DLS), UV-visible (UV-vis) spectrophotometry, atomic force microscopy (AFM), and transmission electron microscopy (TEM).

In vitro metabolic stability of moisture-sensitive rabeprazole in human liver microsomes and its modulation by pharmaceutical excipients.

PubMed

Ren, Shan; Park, Mi-Jin; Kim, Aera; Lee, Beom-Jin

2008-03-01

A reliable method to assess in vitro metabolic stability of rabeprazole and its modulation by Generally Recognized As Safe (GRAS)-listed pharmaceutical excipients was established in human liver microsomes. The metabolic stability of rabeprazole decreased as a function of incubation time, resulting in the formation of thioether rabeprazole via nonenzymatic degradation and enzymatic metabolism. Buffer type was also a determining factor for the degree of both nonenzymatic degradation and enzymatic metabolism. The net extent of enzymatic drug metabolism, obtained by calculating the difference in drug degradation between a microsome-present reaction system and a microsome-free solution, was about 9.20 +/- 0.67% in phosphate buffer and 2.27 +/- 1.76% in Tris buffer, respectively. Rabeprazole exhibited first-order kinetics in microsome-free solution but showed non-linear kinetics in the microsome-present reaction system. The maximal velocity, Vmax, in phosphate buffer was 5.07 microg mL(-1) h(-1) and the Michaelis-Menten constant, Km, was 10.39 microg mL(-1) by computer-fitting to the classical Michaelis-Menten equation for pattern of time-dependent change in the substrate concentration. The intact drug and its thioether form were well resolved and successfully identified by HPLC chromatography and liquid chromatography mass spectroscopy (LC/MS). The metabolic stability of rabeprazole was also modulated by the presence of pharmaceutical excipients. Among the five pharmaceutical excipients tested, poloxamer 188 and Gelucire 44/14 had potentially inhibitory effects on rabeprazole metabolism in human liver microsomes (p < 0.05). A greater understanding of metabolic stability and its modulation by pharmaceutical excipients would be useful for optimizing the bioavailability of rabeprazole at the early formulation stages.

Comparison of immunoexpression of 2 antibodies for estrogen receptors (1D5 and 6F11) in breast carcinomas using different antigen retrieval and detection methods.

PubMed

Vassallo, J; Pinto, G A; Alvarenga, J M; Zeferino, L C; Chagas, C A; Metze, K

2004-06-01

The importance of in situ immunodetection of hormone receptors for therapy planning and prognostic evaluation in patients with breast carcinoma is well established. Sensitive detection methods are of utmost importance, especially in poorly fixed tissues, which are not uncommon in routine pathologic practice. The purpose of the present study is to compare immunoexpression of estrogen receptors in 20 cases of invasive ductal carcinoma using two antibodies, 1D5 and 6F11, and to verify the effect of different antigen retrieval solutions and detection systems. Immunoperoxidase was performed on paraffin sections using 1D5 and 6F11 as primary antibodies. Heat-induced antigen retrieval was performed using citrate buffer (pH 6.0) or Tris-EDTA buffer (pH 8.9). Detection was achieved using the following systems: EnVision, EnVision Plus, and labeled streptavidin-biotin peroxidase complex. Reaction was semiquantified from 0 to 4. There were no differences between the two markers, 1D5 and 6F11, except when 6F11 was used with EnVision and citrate buffer, in which case weaker reactivity was observed. Only in this combination (6F11/EnVision) was EDTA buffer significantly better than citrate. Labeled streptavidin-biotin peroxidase complex presented the best results, followed by EnVision Plus.

Tabun scavengers based on hydroxamic acid containing cyclodextrins.

PubMed

Brandhuber, Florian; Zengerle, Michael; Porwol, Luzian; Bierwisch, Anne; Koller, Marianne; Reiter, Georg; Worek, Franz; Kubik, Stefan

2013-04-28

Arrangement of several hydroxamic acid-derived substituents along the cavity of a cyclodextrin ring leads to compounds that detoxify tabun in TRIS-HCl buffer at physiological pH and 37.0 °C with half-times as low as 3 min.

The effect of EDTA, cations, and various buffers on the morphology of erythrocyte membranes: an electron-microscopic study.

PubMed

Pinteric, L; Manery, J F; Chaudry, I H; Madapallimattam, G

1975-05-01

Membranes of human erythrocytes were prepared by stepwise osmotic hemolysis in Ca2+-free solutions. Examination with the electron microscope after negative staining showed some short, conelike protuberances on the surface of about 20 percent of the ghosts, while 80 percent were round, intact spheres. After Ca2+ treatment, all membranes were round and intact. After exposure to ethylenediaminetetraacetic acid (EDTA) (1.0 mM, pH 7.4), the entire ghost surface was covered with long, thin extrusions called stromalytic forms (about 460 per cell). Their sizes, shapes, and fine structure are described. Exposure to ionic calcium (1.4 times 10-minus 4M) abolished the EDTA-induced stromalytic forms. A second exposure to EDTA reversed this Ca2+ effect. ATP, like EDTA, produced stromalytic forms. EDTA-induced stromalytic forms were also abolished by Zn2+, La3+, and Nd3+ at concentrations of 1-5 times 10-minus 4 M. Mg2+ at 10-minus 2 M was ineffective. Ghosts were prepared by graded lysis in various buffers. Those prepared in phosphate were the most stable and provided consistent EDTA effects and Ca2+ reversal. Ghosts in Tris-HCl showed breakdown unless salt was added. Moderately satisfactory ghosts were also obtained in Hepes-NaOH buffer and salt.

Preparation of polydopamine nanocapsules in a miscible tetrahydrofuran-buffer mixture.

PubMed

Ni, Yun-Zhou; Jiang, Wen-Feng; Tong, Gang-Sheng; Chen, Jian-Xin; Wang, Jie; Li, Hui-Mei; Yu, Chun-Yang; Huang, Xiao-hua; Zhou, Yong-Feng

2015-01-21

A miscible tetrahydrofuran-tris buffer mixture has been used to fabricate polydopamine hollow capsules with a size of 200 nm and with a shell thickness of 40 nm. An unusual non-emulsion soft template mechanism has been disclosed to explain the formation of capsules. The results indicate that the capsule structure is highly dependent on the volume fraction of tetrahydrofuran as well as the solvent, and the shell thickness of capsules can be controlled by adjusting the reaction time and dopamine concentration.

Indirect photometric detection of boron cluster anions electrophoretically separated in methanol.

PubMed

Vítová, Lada; Fojt, Lukáš; Vespalec, Radim

2014-04-18

3,5-Dinitrobenzoate and picrate are light absorbing anions pertinent to indirect photometric detection of boron cluster anions in buffered methanolic background electrolytes (BGEs). Tris(hydroxymethyl)aminomethane and morpholine have been used as buffering bases, which eliminated baseline steps, and minimized the baseline noise. In methanolic BGEs, mobilities of boron cluster anions depend on both ionic constituents of the BGE buffer. This dependence can be explained by ion pair interaction of detected anions with BGE cations, which are not bonded into ion pairs with the BGE anions. The former ion pair interaction decreases sensitivity of the indirect photometric detection. Copyright © 2014 Elsevier B.V. All rights reserved.

An efficient method to eliminate the protease activity contaminating commercial bovine pancreatic DNase I.

PubMed

Le, Tien; Lee, Hak Jin; Jin, Hyung Jong

2015-08-15

A method was developed to eliminate the proteases contaminating commercial DNase I, which can cause degradation of target protein during the purification process. Bio Basic DNase stock solution (in Tris-HCl buffer [pH 8.0] containing 5mM CaCl2) was first incubated at 50 °C to generate autolysis of proteases and zymogens, leading to a significant reduction in protease activity while preserving DNase activity. The residual protease activity was completely inhibited by further incubation with 2mM PMSF (phenylmethylsulfonyl fluoride) or 2× S8830 inhibitor cocktail. This approach could be readily applicable to eliminate the protease activity in any DNase products or during the preparation of commercial DNase. Copyright © 2015 Elsevier Inc. All rights reserved.

Evaluation of agarose gel electrophoresis for characterization of silver nanoparticles in industrial products.

PubMed

Jimenez, Maria S; Luque-Alled, Jose M; Gomez, Teresa; Castillo, Juan R

2016-05-01

Agarose gel electrophoresis (AGE) has been used extensively for characterization of pure nanomaterials or mixtures of pure nanomaterials. We have evaluated the use of AGE for characterization of Ag nanoparticles (NPs) in an industrial product (described as strong antiseptic). Influence of different stabilizing agents (PEG, SDS, and sodium dodecylbenzenesulfonate), buffers (TBE and Tris Glycine), and functionalizing agents (mercaptosuccinic acid (TMA) and proteins) has been investigated for the characterization of AgNPs in the industrial product using different sizes-AgNPs standards. The use of 1% SDS, 0.1% TMA, and Tris Glycine in gel, electrophoresis buffer and loading buffer led to the different sizes-AgNPs standards moved according to their size/charge ratio (obtaining a linear relationship between apparent mobility and mean diameter). After using SDS and TMA, the behavior of the AgNPs in the industrial product (containing a casein matrix) was completely different, being not possible their size characterization. However we demonstrated that AGE with LA-ICP-MS detection is an alternative method to confirm the protein corona formation between the industrial product and two proteins (BSA and transferrin) maintaining NPs-protein binding (what is not possible using SDS-PAGE). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Deduction of a calcium ion circuit affecting rooster sperm in vitro.

PubMed

Froman, D P

2016-08-01

Four premises for rooster sperm preservation were outlined previously. Understanding mitochondrial Ca cycling in terms of whole-cell Ca flux was one premise. The present work tested the hypothesis that sperm mitochondria can be damaged by intracellular as well as extracellular Ca. Sperm were washed by centrifugation through 12% (wt/vol) Sperm were washed by centrifugation through 12%(at/vol) Accudenz to procure sperm at a physiological concentration within a chemically-defined suspension. Five solutions were tested. Each solution contained 30 m glucose, and had an osmolality of 320 mmol/kg and a pH of 7.4. Washed sperm were diluted to 2.0 × 10 sperm/mL. Each replicate sperm suspension was cooled to 10°C. Sperm mobility was measured after 1, 2, 4, 8, 12, and 24 h. Data were plotted as a function of time in each experiment. Function type was confirmed by lack of fit analysis. A parabola with a maximum at 3.7 h was observed when sperm were suspended in 205 m taurine buffered with 50 m-tris[hydroxyl-methyl]methyl-2-amino-ethanesulfonic acid (TES). This effect was attributed to a Ca flux from the nuclear envelope into mitochondria. An exponential decay was observed when TES-buffered taurine contained 2 m Ca. This effect was attributed to mitochondrial Ca overload induced by uptake of extracellular Ca. Exponential decay also was observed when TES-buffered taurine contained a Ca chelator. This effect was attributed to a Ca flux from the nuclear envelope through mitochondria and then into an extracellular Ca sink. This possibility was supported by the response of sperm to thapsigargin. Specifically, inhibition of sarcoendoplasmic reticulum Ca-ATPase compromised sperm mobility relative to a buffer control. Finally, a 60 m phosphate buffer containing 2 m citrate yielded a linear relationship in contrast to the TES-buffered solutions tested. Sperm mobility after 24 h of storage in the phosphate buffer was 92% of that observed for prewashed sperm. The linear response was attributed to weak chelators providing resistance within a Ca circuit and thereby preventing mitochondrial Ca overload. Fertility, however, was compromised when hens were inseminated with mobile sperm recovered after either 8 or 24 h of storage at 10°C. In conclusion, sperm cell Ca homeostasis was proven to be critical for maintaining sperm mobility in vitro, but mitochondrial Ca uptake is not the sole phenomenon that compromises sperm function during in vitro storage.

Extraction-spectrophotometric determination of tris(2-chloroethyl)amine using phthaleins.

PubMed

Rozsypal, Tomas; Halamek, Emil

2017-06-01

Procedures for the extraction-spectrophotometric determination of tris(2-chloroethyl)amine, an alkylating agent known as a drug as well as a chemical warfare agent (nitrogen mustard HN-3), with 7 acid-base indicators of a triphenylmethane lactone type, phthaleins, were developed. Representatives of phthaleins without an oxygen bridge (thymolphthalein, o-cresolphthalein, naphtholphthalein) and with an oxygen bridge (fluorescein, 2',7'-dichlorofluorescein, eosin B and eosin Y) were used. The methods were based on the formation of ion pair complexes. Chloroform was used as a non-polar solvent for an extraction. The conditions to determine were optimized for the optimal pH of the buffer and the concentration of a phthalein as a reagent. The dependence on the reaction time in a water phase and the stoichiometry of extraction products were studied. The detection limits and the limits of the determination of separate procedures and conditional extraction constants were determined. Comparison with the spectrophotometric method of the group determination of alkyl halides and acyl halides using alkaline ethanol-water solution of thymolphthalein, the so-called T-135 agent, was conducted. While studying the selectivity, the possible interference of bis(2-chloroethyl)sulphide and 3 nitrogen mustards in the proposed procedures were verified. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Gel Electrophoresis--The Easy Way for Students

ERIC Educational Resources Information Center

VanRooy, Wilhelmina; Sultana, Khalida

2010-01-01

This article describes a simple, inexpensive, easy to conduct gel-electrophoresis activity using food dyes. It is an alternative to the more expensive counterparts which require agarose gel, DNA samples, purchased chamber and Tris-borate-EDTA buffer. We suggest some learning activities for senior biology students along with comments on several…

Structural and Biochemical Studies of the Ovarian Tumor Domain

DTIC Science & Technology

2007-05-01

solution containing Bis-Tris pH 5.5-6.5, 16-20% PEG 3350 , and 100-200 mM of a magnesium cation. These crystals belong to spacegroup P64 with unit...drop method using a reservoir solution containing Bis-Tris pH 5.5-6.5, 16-20% PEG 3350 , and 50-200 mM ammonium acetate . Orthorhombic crystals

In-vitro effect of edta-tris-lysozyme solutions on selected pathogenic bacteria.

PubMed

Wooley, R E; Blue, J L

1975-02-01

The in-vitro effect of EDTA-Tris-lysozyme solution on 16 pathogenic bacteria of medical or veterinary importance was determined. Marked decreases in bacterial count occurred with Pseudomonas aeruginosa, Escherichia coli, Moraxella osloensis and Campylobacter fetus, and smaller decreses with Salmonella typhimurium, Shigella boydii, Aeromonas hydrophila, proteus mirabilis, Listeria monocytogenes and Erysipelothrix insidiosa. The test solution had no effect on Klebsiella ozaenae, Brucella canis, Cornynebacterium pyogenes, Coryne, renale, Streptococcus equi and staphylococcus aureus.

Coaxial atomic force microscope probes for dielectrophoresis of DNA under different buffer conditions

NASA Astrophysics Data System (ADS)

Tao, Yinglei; Kumar Wickramasinghe, H.

2017-02-01

We demonstrate a coaxial AFM nanoprobe device for dielectrophoretic (DEP) trapping of DNA molecules in Tris-EDTA (TE) and phosphate-buffered saline (PBS) buffers. The DEP properties of 20 nm polystyrene beads were studied with coaxial probes in media with different conductivities. Due to the special geometry of our DEP probe device, sufficiently high electric fields were generated at the probe end to focus DNA molecules with positive DEP. DEP trapping for both polystyrene beads and DNA molecules was quantitatively analyzed over the frequency range from 100 kHz to 50 MHz and compared with the Clausius-Mossotti theory. Finally, we discussed the negative effect of medium salinity during DEP trapping.

Isolation, Cloning and Expression of the Genes for Microbial Polyurethane Degradation

DTIC Science & Technology

1991-05-31

utilizing lysing enzymes, Gluculase and Novozyme , digest the mycelium and produce protoplasts but also tend to digest the DNA. The detergent procedures did...at -20 ’C. Novozyme Procedure One liter of fresh HAFB-2F-Br culture, grown to saturation, was vacuum filtered through Whatman filter paper, #40...resuspended in buffer (15% sucrose, 50 mM Tris pH 7.6, 50 mM EDTA) at 0.2 g filtrate/ml buffer in 15 ml centrifuge tubes. Novozyme was added at 40 mg/ml and

Auto-assembly of nanometer thick, water soluble layers of plasmid DNA complexed with diamines and basic amino acids on graphite: Greatest DNA protection is obtained with arginine.

PubMed

Khalil, T T; Boulanouar, O; Heintz, O; Fromm, M

2017-02-01

We have investigated the ability of diamines as well as basic amino acids to condense DNA onto highly ordered pyrolytic graphite with minimum damage after re-dissolution in water. Based on a bibliographic survey we briefly summarize DNA binding properties with diamines as compared to basic amino acids. Thus, solutions of DNA complexed with these linkers were drop-cast in order to deposit ultra-thin layers on the surface of HOPG in the absence or presence of Tris buffer. Atomic Force Microscopy analyses showed that, at a fixed ligand-DNA mixing ratio of 16, the mean thickness of the layers can be statistically predicted to lie in the range 0-50nm with a maximum standard deviation ±6nm, using a simple linear law depending on the DNA concentration. The morphology of the layers appears to be ligand-dependent. While the layers containing diamines present holes, those formed in the presence of basic amino acids, except for lysine, are much more compact and dense. X-ray Photoelectron Spectroscopy measurements provide compositional information indicating that, compared to the maximum number of DNA sites to which the ligands may bind, the basic amino acids Arg and His are present in large excess. Conservation of the supercoiled topology of the DNA plasmids was studied after recovery of the complex layers in water. Remarkably, arginine has the best protection capabilities whether Tris was present or not in the initial solution. Copyright © 2016 Elsevier B.V. All rights reserved.

Supramolecular gel electrophoresis of large DNA fragments.

PubMed

Tazawa, Shohei; Kobayashi, Kazuhiro; Oyoshi, Takanori; Yamanaka, Masamichi

2017-10-01

Pulsed-field gel electrophoresis is a frequent technique used to separate exceptionally large DNA fragments. In a typical continuous field electrophoresis, it is challenging to separate DNA fragments larger than 20 kbp because they migrate at a comparable rate. To overcome this challenge, it is necessary to develop a novel matrix for the electrophoresis. Here, we describe the electrophoresis of large DNA fragments up to 166 kbp using a supramolecular gel matrix and a typical continuous field electrophoresis system. C 3 -symmetric tris-urea self-assembled into a supramolecular hydrogel in tris-boric acid-EDTA buffer, a typical buffer for DNA electrophoresis, and the supramolecular hydrogel was used as a matrix for electrophoresis to separate large DNA fragments. Three types of DNA marker, the λ-Hind III digest (2 to 23 kbp), Lambda DNA-Mono Cut Mix (10 to 49 kbp), and Marker 7 GT (10 to 165 kbp), were analyzed in this study. Large DNA fragments of greater than 100 kbp showed distinct mobility using a typical continuous field electrophoresis system. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rapid diagnosis of soybean mosaic virus N soybean by tissue-print immunoassay and DIBA in comparison to other serological methods.

PubMed

Ahangaran, A; Mohammadi, Gh Mosahebi; Habibi, M Koohi; Shahraeen, N; Khezri, S

2006-01-01

Soybean mosaic virus (SMV) is an important disease in soybean and is widely distributed in northern of Iran. SMV transmitted by soybean seed and detection of it is very important for disease management. In this study, several detection methods including DAS-ELISA, indirect-ELISA, tissue-print immunoassay (TPIA) and Dot immunobinding assay (DIBA) were optimized and compared with each other to identify the virus, using polyclonal antibody. For TPIA, nitrocellulose membrane was used to imprint fresh sections of healthy and infected plant materials, and for DIBA 10 microl of extracts was doted onto nitrocellulose membranes. Both membranes were incubated 1 hour in blocking buffer, and then incubated 2 h in 1:1000 dilution of IgG-conjugate. After incubation the membranes were washed three times with PBS-T buffer for 15 min. Then the membranes were incubated in substrate solution containing NBT/BCIP. After some minutes prints or blots of infected tissues turned dark violet, whereas prints or blots of healthy ones did not show any color changes. In some cases, substrate solution was Fast red, containing 0.2M Tris-HCl buffer and 2mM MgCl2, pH = 7.8, producing red color in infected prints or blots. Both methods are simple and TPIA is rapidly and easily applicable in the field. However, TPIA had some advantages over the others. TPIA is time-saving as there is no need for conventional sap extraction and also nitrocellulose membranes used for printing can be used in the field and stored for a long time or transported to another laboratory for process. These two methods can be used routinely for detection of SMV in many samples.

Comparison of different extenders on the recovery and longevity of epididymal sperm from Spix's yellow-toothed cavies (Galea spixii Wagler, 1831).

PubMed

da Silva, Andréia Maria; Sousa, Patrícia Cunha; Campos, Lívia Batista; Bezerra, José Artur Brilhante; de Araújo Lago, Arthur Emannuel; de Oliveira, Moacir Franco; Silva, Alexandre Rodrigues

2017-04-01

The aim of this study was to evaluate the performance of cavy (Galea spixii) epididymal sperm following addition to TES or TRIS extenders and using a thermal resistance test (TRT), as well as fluorescence analysis as a complementary method to predict the viability of these gametes. Nine testicle-epididymis complexes were used for sperm collection using a flotation method. Epididymis tails were sliced and one was immersed in 3 ml of TRIS buffer, and the other in 3 ml of TES, for 5 min. After sperm recovery, the samples were subjected to a TRT which involved incubation in a water bath at 37°C for 3 h. During incubation, sample parameters were assessed at 0, 15, 30, 60, 90, 120, 150 or 180 min intervals. Results indicated that the TRIS diluent was more efficient than TES (P < 0.05) for the maintenance of sperm parameters in Spix's yellow-toothed cavies over the whole TRT, maintaining sperm longevity for an extended time. In conclusion, we indicate the use of TRIS diluent for recovery and maintenance of longevity of epididymal sperm from cavies (G. spixii).

Oxidation-reduction potentials of molybdenum, flavin and iron-sulphur centres in milk xanthine oxidase.

PubMed Central

Cammack, R; Barber, M J; Bray, R C

1976-01-01

1. The mid-point reduction potentials of the various groups in xanthine oxidase from bovine milk were determined by potentiometric titration with dithionite in the presence of dye mediators, removing samples for quantification of the reduced species by e.p.r. (electron-paramagnetic-resonance) spectroscopy. The values obtained for the functional enzyme in pyrophosphate buffer, pH8.2, are: Fe/S centre I, -343 +/- 15mV; Fe/S II, -303 +/- 15mV; FAD/FADH-; -351 +/- 20mV; FADH/FADH2, -236 +/-mV; Mo(VI)/Mo(V) (Rapid), -355 +/- 20mV; Mo(V) (Rapid)/Mo(IV), -355 +/- 20mV. 2. Behaviour of the functional enzyme is essentially ideal in Tris but less so in pyrophosphate. In Tris, the potential for Mo(VI)/Mo(V) (Rapid) is lowered relative to that in pyrophosphate, but the potential for Fe/S II is raised. The influence of buffer on the potentials was investigated by partial-reduction experiments with six other buffers. 3. Conversion of the enzyme with cyanide into the non-functional form, which gives the Slow molybdenum signal, or alkylation of FAD, has little effect on the mid-point potentials of the other centres. The potentials associated with the Slow signal are: Mo(VI)/Mo(V) (Slow), -440 +/- 25mV; Mo(V) (Slow)/Mo(IV), -480 +/- 25 mV. This signal exhibits very sluggish equilibration with the mediator system. 4. The deviations from ideal behaviour are discussed in terms of possible binding of buffer ions or anti-co-operative interactions amongst the redox centres. PMID:183752

Terbium to Quantum Dot FRET Bioconjugates for Clinical Diagnostics: Influence of Human Plasma on Optical and Assembly Properties

PubMed Central

Morgner, Frank; Stufler, Stefan; Geißler, Daniel; Medintz, Igor L.; Algar, W. Russ; Susumu, Kimihiro; Stewart, Michael H.; Blanco-Canosa, Juan B.; Dawson, Philip E.; Hildebrandt, Niko

2011-01-01

Förster resonance energy transfer (FRET) from luminescent terbium complexes (LTC) as donors to semiconductor quantum dots (QDs) as acceptors allows extraordinary large FRET efficiencies due to the long Förster distances afforded. Moreover, time-gated detection permits an efficient suppression of autofluorescent background leading to sub-picomolar detection limits even within multiplexed detection formats. These characteristics make FRET-systems with LTC and QDs excellent candidates for clinical diagnostics. So far, such proofs of principle for highly sensitive multiplexed biosensing have only been performed under optimized buffer conditions and interactions between real-life clinical media such as human serum or plasma and LTC-QD-FRET-systems have not yet been taken into account. Here we present an extensive spectroscopic analysis of absorption, excitation and emission spectra along with the luminescence decay times of both the single components as well as the assembled FRET-systems in TRIS-buffer, TRIS-buffer with 2% bovine serum albumin, and fresh human plasma. Moreover, we evaluated homogeneous LTC-QD FRET assays in QD conjugates assembled with either the well-known, specific biotin-streptavidin biological interaction or, alternatively, the metal-affinity coordination of histidine to zinc. In the case of conjugates assembled with biotin-streptavidin no significant interference with the optical and binding properties occurs whereas the histidine-zinc system appears to be affected by human plasma. PMID:22163719

Soy matrix drug delivery systems obtained by melt-processing techniques.

PubMed

Vaz, Cláudia M; van Doeveren, Patrick F N M; Reis, Rui L; Cunha, António M

2003-01-01

The aim of this study was to develop new soy protein drug delivery matrix systems by melt-processing techniques, namely, extrusion and injection moulding. The soy matrix systems with an encapsulated drug (theophylline, TH) were previously compounded by extrusion performed at two different pH values, (i) pH 4 (SIpDtp) and (ii) pH 7 (SIDtp), and further injection-moulded into a desired shape. During the extrusion process the matrixes SIDtp were also cross-linked with glyoxal (0.6X-SIDtp) and reinforced with a bioactive filler, hydroxylapatite (SI-HADtp). The obtained mouldings were used to study the drug-release mechanisms from the plastic soy-TH matrixes. In an isotonic saline solution (ISS) buffered at pH 5.0 (200 mM acetate buffer), the resulting release kinetics could be described using the Fick's second law of diffusion. Because the diffusion coefficients were found to be constant and the boundary conditions to be stationary, these systems are drug-diffusion controlled. Conversely, the dominant phenomena in an isotonic saline solution buffered at pH 7.4 (200 mM Tris/HCl buffer) are more complex. In fact, because of the higher polymer solubility, the resulting matrix is time-variant. So, the drug release is affected by swelling, drug diffusion, and polymer dissolution, being faster when compared to ISS-200 mM acetate buffer, pH 5.0. The changes in the formulation composition affecting the correspondent release rates were also investigated. At pH 7.4, increasing the cross-linking degree of the polymer matrix (via reaction with glyoxal or heat treatment) or decreasing the net charge (extruding at pH near its isoelectric point) led to lower release rates. The incorporation of ceramic filler caused the opposite effect. Because of the low solubility of the matrix at pH 5.0, no significant variations were detected with variations in the selected formulations. These systems, based on a nonstandard protein-based material, seem to be very promising to be used as carriers for drug delivery.

A versatile electrophoresis system for the analysis of high- and low-molecular-weight proteins

PubMed Central

Tastet, Christophe; Lescuyer, Pierre; Diemer, Hélène; Luche, Sylvie; van Dorsselaer, Alain; Rabilloud, Thierry

2003-01-01

A new, versatile, multiphasic buffer system for high resolution sodium dodecyl sulfatepolyacrylamide gel electrophoresis of proteins in the relative molecular weight Mw range of 300,000-3000 Da is described. The system, based on the theory of multiphasic zone electrophoresis, allows complete stacking and destacking of proteins in the above Mw range. The buffer system uses taurine and chloride as trailing and leading ion, respectively, and Tris, at a pH close to its pKa, as the buffering counter ion. Coupled with limited variation in the acrylamide concentration, this electrophoresis system allows to tailor the resolution in the 6–200 kDa Mw range, with minimal difficulties in the post electrophoretic identification processes. PMID:12783456

Dominant Negative Mutants of the Estrogen Receptor as Probes of Estrogen Action and Inhibitors of Breast Cancer Growth

DTIC Science & Technology

1996-07-01

tetrazolium, inner salt; MTS; Promega], 1.9 mg/ml, and an electron coupling reagent ( phenazine methosulfate; PMS; Sigma), 0.044 mg/ml, in Dulbecco’s...acids PBS, phosphate buffered saline PCR, polymerase chain reaction PMS, phenazine methosulfate poly A, polyadenylation s.e., standard error TAE, tris

No filters, no fridges: a method for preservation of water samples for eDNA analysis.

PubMed

Williams, Kelly E; Huyvaert, Kathryn P; Piaggio, Antoinette J

2016-06-08

Advancements in the detection of environmental DNA (eDNA) for detecting species of interest will likely allow for expanded use of these techniques in the field. One obstacle that continues to hinder applications in the field is the requirement of a cold chain of storage for water samples containing eDNA. While eDNA has been successfully preserved using Longmire's lysis buffer applied to filters, it has yet to be tried with freshwater samples collected for eDNA detection of an invasive species. We tested the utility of Longmire's solution (100 mM Tris, 100 mM EDTA, 10 mM NaCl, 0.5 % SDS, 0.2 % sodium azide) as an additive to freshwater samples for preservation of eDNA. Environmental DNA was effectively preserved in 15 mL water samples with Longmire's solution added; eDNA positive detection was comparable to freezing the samples at -80 °C and occurred out to 56 days at the highest concentration (5 mL Longmire's solution: 15 mL sample water). Medium and low concentrations of Longmire's solution added to 15 mL of sample water generally preserved eDNA out to 56 days but not as well as did freezing or application of the highest concentration of Longmire's lysis buffer. Treatment and degradation time had a significant effect on average DNA concentration of samples, although not the interaction of treatment and time. Perfect detection occurred out to 56 days with the high Longmire's treatment group but DNA concentration was significantly lower at this time point compared to 28 days. We conclude that Longmire's lysis buffer is a viable alternative to cold chain storage that can simplify the collection of eDNA by eliminating the need for filtering and allow more time for sample collection when added at our highest concentration (1 part Longmire's:3 parts water sample), which could translate to an increase in the chances of detecting a rare or elusive species.

Peptide surface modification of P(HEMA-co-MMA)-b-PIB-b-P(HEMA-co-MMA) block copolymers.

PubMed

Ojha, Umaprasana; Feng, Dingsong; Chandekar, Amol; Whitten, James E; Faust, Rudolf

2009-06-02

Peptide surface modification of poly[(methyl methacrylate-co-hydroxyethyl methacrylate)-b-isobutylene-b-(methyl methacrylate-co-hydroxyethyl methacrylate)] P(MMA-co-HEMA)-b-PIB-b-P(MMA-co-HEMA) triblock copolymers with different HEMA/MMA ratios has been accomplished using an efficient synthetic procedure. The triblock copolymers were reacted with 4-fluorobenzenesulfonyl chloride (fosyl chloride) in pyridine to obtain the activated polymers [poly{(methyl methacrylate-co-fosyloxyethyl methacrylate)-b-isobutylene-b-(methyl methacrylate-co-fosyloxyethyl methacrylate)}] P(MMA-co-FEMA)-b-PIB-b-P(MMA-co-FEMA), with an activating efficiency of 80-90%. The resulting polymers were soluble in chloroform, and their solutions were used to coat thin uniform films with a predetermined thickness on smooth steel surfaces. The presence of reactive activating groups on the film surface was confirmed by X-ray photoelectron spectroscopy (XPS), dye labeling, and confocal laser scanning microscopic studies. Activation of the triblock copolymer films was also achieved under heterogeneous conditions in polar (acetonitrile) and nonpolar (hexanes) media. The extent of activation was controlled by varying the dipping time and polarity of the medium. Peptide attachment was accomplished by immersing the coated steel strips into aqueous buffer solution of Gly-Gly or GYIGSR. XPS and solubility studies revealed successful attachment of peptides to the polymer surface. Virtually all remaining activating groups were successfully replaced in the subsequent step by a treatment with Tris(hydroxymethyl)amino methane in a buffered methanol/water mixture.

Calcium manganese(IV) oxides: biomimetic and efficient catalysts for water oxidation.

PubMed

Najafpour, Mohammad Mahdi; Pashaei, Babak; Nayeri, Sara

2012-04-28

CaMnO(3) and Ca(2)Mn(3)O(8) were synthesized and characterized by SEM, XRD, FTIR and BET. Both oxides showed oxygen evolution activity in the presence of oxone, cerium(IV) ammonium nitrate and H(2)O(2). Oxygen evolution from water during irradiation with visible light (λ > 400 nm) was also observed upon adding these manganese oxides to an aqueous solution containing tris(2,2'-bipyridyl) ruthenium(II), as photosensitizer, and chloro pentaammine cobalt(III) chloride, as electron acceptor, in an acetate buffer. The amounts of dissolved manganese and calcium from CaMnO(3) and Ca(2)Mn(3)O(8) in the oxygen evolving reactions were reported and compared with other (calcium) manganese oxides. Proposed mechanisms of oxygen evolution and proposed roles for the calcium ions are also considered. This journal is © The Royal Society of Chemistry 2012

Interactions between globular proteins and F-actin in isotonic saline solution.

PubMed

Lakatos, S; Minton, A P

1991-10-05

Solutions of each of three different globular proteins (cytochrome c, chromophorically labeled serum albumin, and chromophorically labeled aldolase), mixed with another unlabeled globular protein or with fibrous actin, were prepared in pH 8.0 Tris-HCl buffer containing 0.15 M NaCl. Each solution was centrifuged at low speed, at 5 degrees C, until unassociated globular protein in solution achieved sedimentation equilibrium. Individual absorbance gradients of both macrosolutes in the mixtures subsequent to centrifugation were obtained via optical scans of the centrifuge tubes at two wavelengths. The gradients of each macrosolute in mixtures of two globular proteins revealed no association of globular proteins under the conditions of these experiments, but perturbation of the gradients of serum albumin, aldolase, and cytochrome c in the presence of F-actin indicated association of all three globular proteins with F-actin. Perturbation of actin gradients in the presence of serum albumin and aldolase suggested partial depolymerization of the F-actin by the globular protein. Analysis of the data with a simple phenomenological model relating free globular protein, bound globular protein, and total actin concentration provided estimates of the respective equilibrium constants for association of serum albumin and aldolase with F-actin, under the conditions of these experiments, of the order of 0.1 microM-1.

Tunneling Injection and Exciton Diffusion of White Organic Light-Emitting Diodes with Composed Buffer Layers

NASA Astrophysics Data System (ADS)

Yang, Su-Hua; Wu, Jian-Ping; Huang, Tao-Liang; Chung, Bin-Fong

2018-02-01

Four configurations of buffer layers were inserted into the structure of a white organic light emitting diode, and their impacts on the hole tunneling-injection and exciton diffusion processes were investigated. The insertion of a single buffer layer of 4,4'-bis(carbazol-9-yl)biphenyl (CBP) resulted in a balanced carrier concentration and excellent color stability with insignificant chromaticity coordinate variations of Δ x < 0.023 and Δ y < 0.023. A device with a 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) buffer layer was beneficial for hole tunneling to the emission layer, resulting in a 1.45-fold increase in current density. The tunneling of holes and the diffusion of excitons were confirmed by the preparation of a dual buffer layer of CBP:tris-(phenylpyridine)-iridine (Ir(ppy)3)/BCP. A maximum current efficiency of 12.61 cd/A with a luminance of 13,850 cd/m2 was obtained at 8 V when a device with a dual-buffer layer of CBP:6 wt.% Ir(ppy)3/BCP was prepared.

Plasma creatinine and creatine quantification by capillary electrophoresis diode array detector.

PubMed

Zinellu, Angelo; Caria, Marcello A; Tavera, Claudio; Sotgia, Salvatore; Chessa, Roberto; Deiana, Luca; Carru, Ciriaco

2005-07-15

Traditional clinical assays for nonprotein nitrogen compounds, such as creatine and creatinine, have focused on the use of enzymes or chemical reactions that allow measurement of each analyte separately. Most of these assays are mainly directed to urine quantification, so that their applicability on plasma samples is frequently hard to perform. This work describes a simple free zone capillary electrophoresis method for the simultaneous measurement of creatinine and creatine in human plasma. The effect of analytical parameters such as concentration and pH of Tris-phosphate running buffer and cartridge temperature on resolution, migration times, peak areas, and efficiency was investigated. Good separation was achieved using a 60.2-cm x 75-microm uncoated silica capillary, 75 mmol/L Tris-phosphate buffer, pH 2.25, at 15 degrees C, in less than 8 min. We compared the present method to a validated capillary electrophoresis assay, by measuring plasma creatinine in 120 normal subjects. The obtained data were compared by the Passing-Bablok regression and the Bland-Altman test. Moreover the performance of the developed method was assessed by measuring creatine and creatinine in 16 volunteers prior to and after a moderate physical exercise.

Transition state analogue imprinted polymers as artificial amidases for amino acid p-nitroanilides: morphological effects of polymer network on catalytic efficiency.

PubMed

Mathew, Divya; Thomas, Benny; Devaky, K S

2017-11-13

The morphology of the polymer network - porous/less porous - plays predominant role in the amidase activities of the polymer catalysts in the hydrolytic reactions of amino acid p-nitroanilides. Polymers with the imprints of stable phosphonate analogue of the intermediate of hydrolytic reactions were synthesized as enzyme mimics. Molecular imprinting was carried out in thermodynamically stable porogen dimethyl sulphoxide and unstable porogen chloroform, to investigate the morphological effects of polymers on catalytic amidolysis. It was found that the medium of polymerization has vital influence in the amidase activities of the enzyme mimics. The morphological studies of the polymer catalysts were carried out by scanning electron microscopy and Bruner-Emmett-Teller analysis. The morphology of the polymer catalysts and their amidase activities are found to be dependent on the composition of reaction medium. The polymer catalyst prepared in dimethyl sulphoxide is observed to be efficient in 1:9 acetonitrile (ACN)-Tris HCl buffer and that prepared in chloroform is noticed to be stereo specifically and shape-selectively effective in 9:1 ACN-Tris HCl buffer. The solvent memory effect in catalytic amidolysis was investigated using the polymer prepared in acetonitrile.

Energy coupling to nitrate uptake into the denitrifying cells of Paracoccus denitrificans.

PubMed

Kucera, Igor

2005-09-05

This study deals with the effects of the agents that dissipate the individual components of the proton motive force (short-chain fatty acids, nigericin, and valinomycin) upon the methyl viologen-coupled nitrate reductase activity in intact cells. Substitution of butyrate or acetate for chloride in Tris-buffered assay media resulted in a marked inhibition at pH 7. In a Tris--chloride buffer of neutral pH, the reaction was almost fully inhibitable by nigericin. Alkalinisation increased the IC(50) value for nigericin and decreased the maximal inhibition attained. Both types of inhibitions could be reversed by the permeabilisation of cells or by the addition of nitrite, and that caused by nigericin disappeared at high extracellular concentrations of potassium. These data indicate that nitrate transport step relies heavily on the pH gradient at neutral pH. Since the affinity of cells for nitrate was strongly diminished by imposing an inside-positive potassium (or lithium) diffusion potential at alkaline external pH, a potential dependent step may be of significance in the transporter cycle under these conditions. Experiments with sodium-depleted media provided no hints for Na(+) as a possible H(+) substitute.

Plaquing procedure for infectious hematopoietic necrosis virus

USGS Publications Warehouse

Burke, J.A.; Mulcahy, D.

1980-01-01

A single overlay plaque assay was designed and evaluated for infectious hematopoietic necrosis virus. Epithelioma papillosum carpio cells were grown in normal atmosphere with tris(hydroxymethyl)aminomethane- or HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid)-buffered media. Plaques were larger and formed more quickly on 1- to 3-day-old cell monolayers than on older monolayers. Cell culture medium with a 10% addition of fetal calf serum (MEM 10) or without serum (MEM 0) were the most efficient virus diluents. Dilution with phosphate-buffered saline, saline, normal broth, or deionized water reduced plaque numbers. Variations in the pH (7.0 to 8.0) of a MEM 0 diluent did not affect plaque numbers. Increasing the volume of viral inoculum above 0.15 ml (15- by 60-mm plate) decreased plaquing efficiency. Significantly more plaques occurred under gum tragacanth and methylcellulose than under agar or agarose overlays. Varying the pH (6.8 to 7.4) of methylcellulose overlays did not significantly change plaque numbers. More plaques formed under the thicker overlays of both methylcellulose and gum tragacanth. Tris(hydroxymethyl)aminomethane and HEPES performed equally well, buffering either medium or overlay. Plaque numbers were reduced when cells were rinsed after virus adsorption or less than 1 h was allowed for adsorption. Variation in adsorption time between 60 and 180 min did not change plaque numbers. The mean plaque formation time was 7 days at 16 degrees C. The viral dose response was linear when the standardized assay was used.

Determination of the Solubility Limit of Tris(dibenzylideneacetone) Dipalladium(0) in Tetrahydrofuran/Water Mixtures

ERIC Educational Resources Information Center

Franzen, Stefan

2011-01-01

Determination of the solubility limit of a strongly colored organometallic reagent in a mixed-solvent system provides an example of quantitative solubility measurement appropriate to understand polymer, nanoparticle, and other macromolecular aggregation processes. The specific example chosen involves a solution of tris(dibenzylideneacetone)…

A glycoprotein from mammary gland secreted during involution promotes apoptosis: Structural and biological studies.

PubMed

Chaudhary, Anshul; Kumar, Vinod; Singh, Prashant K; Sharma, Pradeep; Bairagya, Hridoy R; Kaur, Punit; Sharma, Sujata; Chauhan, Shyam S; Singh, Tej P

2018-04-15

Secretory signalling glycoprotein (SPX-40) from mammary gland is highly expressed during involution. This protein is involved in a programmed cell death during tissue remodelling which occurs at the end of lactation. SPX-40 was isolated and purified from buffalo (SPB-40) from the samples obtained during involution. One solution of SPB-40 was made by dissolving it in buffer containing 25 mM Tris-HCl and 50 mM NaCl at pH 8.0. Another solution was made by adding 25% ethanol to the above solution. The biological effects of SPB-40 dissolved in above two solutions were evaluated on MCF-7 breast cancer cell lines. Free SPB-40 indicated significant pro-apoptotic effects while ethanol exposed SPB-40 showed considerably reduced effects on the apoptosis. SPB-40 was crystallized in the native state. The crystals of SPB-40 were soaked in four separate solutions containing 25% acetone, 25% ethanol, 25% butanol and 25% MPD. Four separate data sets were collected and their structures were determined at high resolutions. In all the four structures, the molecules of acetone, ethanol, butanol and MPD respectively were observed in the hydrophobic binding pocket of SPB-40. As a result of which, the conformation of Trp78 was altered thus blocking the binding site in SPB-40 leading to the loss of activity. Copyright © 2018. Published by Elsevier Inc.

Electrophoresis of DNA in agarose gels, polyacrylamide gels and in free solution

PubMed Central

Stellwagen, Nancy C.

2009-01-01

This review describes the electrophoresis of curved and normal DNA molecules in agarose gels, polyacrylamide gels and in free solution. These studies were undertaken to clarify why curved DNA molecules migrate anomalously slowly in polyacrylamide gels but not in agarose gels. Two milestone papers are cited, in which Ferguson plots were used to estimate the effective pore size of agarose and polyacrylamide gels. Subsequent studies on the effect of the electric field on agarose and polyacrylamide gel matrices, DNA interactions with the two gel matrices, and the effect of curvature on the free solution mobility of DNA are also described. The combined results suggest that the anomalously slow mobilities observed for curved DNA molecules in polyacrylamide gels are due primarily to preferential interactions of curved DNAs with the polyacrylamide gel matrix; the restrictive pore size of the matrix is of lesser importance. In free solution, DNA mobilities increase with increasing molecular mass until leveling off at a plateau value of (3.17 ± 0.01) × 10-4 cm2/Vs in 40 mM Tris-acetate-EDTA buffer at 20°C. Curved DNA molecules migrate anomalously slowly in free solution as well as in polyacrylamide gels, explaining why the Ferguson plots of curved and normal DNAs containing the same number of base pairs extrapolate to different mobilities at zero gel concentration. PMID:19517510

An improved glycerol biosensor with an Au-FeS-NAD-glycerol-dehydrogenase anode.

PubMed

Mahadevan, Aishwarya; Fernando, Sandun

2017-06-15

An improved glycerol biosensor was developed via direct attachment of NAD + -glycerol dehydrogenase coenzyme-apoenzyme complex onto supporting gold electrodes, using novel inorganic iron (II) sulfide (FeS)-based single molecular wires. Sensing performance factors, i.e., sensitivity, a detection limit and response time of the FeS and conventional pyrroloquinoline quinone (PQQ)-based biosensor were evaluated by dynamic constant potential amperometry at 1.3V under non-buffered conditions. For glycerol concentrations ranging from 1 to 25mM, a 77% increase in sensitivity and a 53% decrease in detection limit were observed for the FeS-based biosensor when compared to the conventional PQQ-based counterpart. The electrochemical behavior of the FeS-based glycerol biosensor was analyzed at different concentrations of glycerol, accompanied by an investigation into the effects of applied potential and scan rate on the current response. Effects of enzyme stimulants ((NH 4 ) 2 SO 4 and MnCl 2 ·4H 2 O) concentrations and buffers/pH (potassium phosphate buffer pH 6-8, Tris buffer pH 8-10) on the current responses generated by the FeS-based glycerol biosensor were also studied. The optimal detection conditions were 0.03M (NH 4 ) 2 SO 4 and 0.3µm MnCl 2 ·4H 2 O in non-buffered aqueous electrolyte under stirring whereas under non-stirring, Tris buffer at pH 10 with 0.03M (NH 4 ) 2 SO 4 and 30µm MnCl 2 ·4H 2 O were found to be optimal detection conditions. Interference by glucose, fructose, ethanol, and acetic acid in glycerol detection was studied. The observations indicated a promising enhancement in glycerol detection using the novel FeS-based glycerol sensing electrode compared to the conventional PQQ-based one. These findings support the premise that FeS-based bioanodes are capable of biosensing glycerol successfully and may be applicable for other enzymatic biosensors. Copyright © 2016 Elsevier B.V. All rights reserved.

Stopped-flow studies of the reaction of D-tartronate semialdehyde-2-phosphate with human neuronal enolase and yeast enolase 1.

PubMed

Brewer, John M; McKinnon, Jared S; Phillips, Robert S

2010-03-05

We determined the kinetics of the reaction of human neuronal enolase and yeast enolase 1 with the slowly-reacting chromophoric substrate D-tartronate semialdehyde phosphate (TSP), each in tris (tris (hydroxymethyl) aminomethane) and another buffer at several Mg2+ concentrations, 50 or 100 microM, 1 mM and 30 mM. All data were biphasic, and could be satisfactorily fit, assuming either two successive first-order reactions or two independent first-order reactions. Higher Mg2+ concentrations reduce the relative magnitude of the slower reaction. The results are interpreted in terms of a catalytically significant interaction between the two subunits of these enzymes. Copyright (c) 2010 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Predicting stability of DNA duplexes in solutions containing magnesium and monovalent cations.

PubMed

Owczarzy, Richard; Moreira, Bernardo G; You, Yong; Behlke, Mark A; Walder, Joseph A

2008-05-13

Accurate predictions of DNA stability in physiological and enzyme buffers are important for the design of many biological and biochemical assays. We therefore investigated the effects of magnesium, potassium, sodium, Tris ions, and deoxynucleoside triphosphates on melting profiles of duplex DNA oligomers and collected large melting data sets. An empirical correction function was developed that predicts melting temperatures, transition enthalpies, entropies, and free energies in buffers containing magnesium and monovalent cations. The new correction function significantly improves the accuracy of predictions and accounts for ion concentration, G-C base pair content, and length of the oligonucleotides. The competitive effects of potassium and magnesium ions were characterized. If the concentration ratio of [Mg (2+)] (0.5)/[Mon (+)] is less than 0.22 M (-1/2), monovalent ions (K (+), Na (+)) are dominant. Effects of magnesium ions dominate and determine duplex stability at higher ratios. Typical reaction conditions for PCR and DNA sequencing (1.5-5 mM magnesium and 20-100 mM monovalent cations) fall within this range. Conditions were identified where monovalent and divalent cations compete and their stability effects are more complex. When duplexes denature, some of the Mg (2+) ions associated with the DNA are released. The number of released magnesium ions per phosphate charge is sequence dependent and decreases surprisingly with increasing oligonucleotide length.

Concurrent determination of total serum calcium and magnesium by thermometric titration with ethylenediaminetetraacetate.

PubMed

Callicott, R H; Carr, P W

1976-07-01

Total serum calcium and magnesium may be determined in one thermometric titration, with disodium ethylenediaminetetraacetate as the titrant. A 1-ml serum sample is diluted with 1 ml of tris(hydroxymethyl)aminomethane buffer (pH 8) and titrated at a constant rate with a motorized syringe buret. Results by the thermometric method compared well with those by atomic absorption spectroscopy.

Agarose electrophoresis of DNA in discontinuous buffers, using a horizontal slab apparatus and a buffer system with improved properties.

PubMed

Zsolnai, A; Orbán, L; Chrambach, A

1993-03-01

Using a horizontal slab apparatus with a buffer in the reservoirs at the level of the gel ("sea-level electrophoresis"), the retrograde discontinuous buffer system reported by Wiltfang et al. for sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of proteins was applied to DNA electrophoresis. This application yielded the advantages of an increased displacement rate of the moving boundary front and a decrease in the concentration of the counterion base in the resolving phase, which yielded reduced relative mobility values at equivalent gel concentrations and practicable low buffer concentrations. The change of relative mobilities (Rf) with a variation of field strength is decreased compared to that of the migration rate in the continuous Tris-boric-acid-EDTA (TBE) buffer and thus the robustness of the system is improved, as well as the efficiency of separation. The system of Wiltfang et al. has in common with previously described discontinuous DNA system, that it is able to stack DNA from dilute samples and is insensitive to sample components with lower net mobilities than DNA, such as acetate. However, the variance of Rf at constant current density in the discontinuous buffer system is not improved over that of the migration rate at constant field strength in the continuous TBE buffer.

Dehydration of bacteriophages in electrospun nanofibers: effect of excipients in polymeric solutions

NASA Astrophysics Data System (ADS)

Koo, Charmaine K. W.; Senecal, Kris; Senecal, Andre; Nugen, Sam R.

2016-12-01

Bacteriophages are viruses capable of infecting and lysing target bacterial cells; as such they have potential applications in agriculture for decontamination of foods, food contact surfaces and food rinse water. Although bacteriophages can retain infectivity long-term using lyophilized storage, the process of freeze-drying can be time consuming and expensive. In this study, electrospinning was used for dehydrating bacteriophages in polyvinylpyrrolidone polymer solutions with addition of excipients (sodium chloride, magnesium sulfate, Tris-HCl, sucrose) in deionized water. The high voltage dehydration reduced the infectivity of bacteriophages following electrospinning, with the damaging effect abated with addition of storage media (SM) buffer and sucrose. SM buffer and sucrose also provided the most protection over extended storage (8 weeks; 20 °C 1% relative humidity) by mitigating environmental effects on the dried bacteriophages. Magnesium sulfate however provided the least protection due to coagulation effects of the ion, which can disrupt the native conformation of the bacteriophage protein coat. Storage temperatures (20 °C, 4 °C and -20 °C 1% relative humidity) had a minimal effect while relative humidity had substantial effect on the infectivity of bacteriophages. Nanofibers stored in higher relative humidity (33% and 75%) underwent considerable damage due to extensive water absorption and disruption of the fibers. Overall, following storage of nanofiber mats for eight weeks at ambient temperatures, high infective phage concentrations (106-107 PFU ml-1) were retained. Therefore, this study provided valuable insights on preservation and dehydration of bacteriophages by electrospinning in comparison to freeze drying and liquid storage, and the influence of excipients on the viability of bacteriophages.

Polydopamine-induced tooth remineralization.

PubMed

Zhou, Yun-Zhi; Cao, Ying; Liu, Wei; Chu, Chun Hung; Li, Quan-Li

2012-12-01

Inspired by mussel bioadhesion in nature, dopamine is extensively used for biomaterial surface modification. In this study, we coated dopamine on demineralized enamel and dentin surfaces to evaluate the effect of polydopamine coating on dental remineralization. Dental slices containing enamel and dentin were first etched with 37% phosphoric acid for 2 min, followed by immersion in a 2 mg/mL freshly prepared solution of dopamine (10 mM Tris buffer, pH 8.5) for approximately 24 h at room temperature in the dark to obtain polydopamine coating. Then, the dental slices with and without polydopamine coating were immersed in the supersaturated solution of calcium and phosphate at 37 °C for 2 and 7 days. The supersaturated solution of calcium and phosphate was refreshed each day. The precipitates were characterized by SEM, XRD, FTIR, microhardness, and nanoscratch analyses. No significant difference was observed in the remineralization of enamel whether it was coated with polydopamine or not. However, a significant difference was found in dentin remineralization between dentin with and without polydopamine coating. Polydopamine coating remarkably promoted demineralized dentin remineralization, and all dentin tubules were occluded by densely packed hydroxyapatite crystals. Thus, coating polydopamine on dental tissue surface may be a simple universal technique to induce enamel and dentin remineralization simultaneously.

Two new glucose 6-phosphate dehydrogenase variants associated with congenital nonspherocytic hemolytic anemia found in Japan: GD(-) Tokushima and GD(-) Tokyo.

PubMed

Miwa, S; Ono, J; Nakashima, K; Abe, S; Kageoka, T

1976-01-01

Two new variants of glucose 6-phosphate dehydrogenase (G6PD) deficiency associated with chronic nonspherocytic hemolytic anemia were discovered in Japan. Gd(-) Tokushima was found in a 17-years-old male whose erythrocytes contained 4.4% of normal enzyme activity. Partially purified enzyme revealed a main band of normal electrophoretic mobility with additional two minor bands of different mobility; normal Km G6P, and Km NADP five-to sixfold higher than normal; normal utilization of 2-deoxy-G6P, galactose-6P, and deamino-NADP; marked thermal instability; a normal pH curve; and normal Ki NADPH. The hemolytic anemia was moderate to severe. Gd(-) Tokyo was characterized from a 15-year-old male who had chronic nonspherocytic hemolytic anemia of mild degree. The erythrocytes contained 3% of normal enzyme activity, and partially purified enzyme revealed slow electrophoretic mobility (90% of normal for both a tris-hydrochloride buffer system and a tris-EDTA-borate buffer system, and 70% of normal for a phosphate buffer system); normal Km G6P and Km NADP; normal utilization of 2-deoxy-G6P, galactose-6P, and deamino-NADP; greatly increased thermal instability; a normal pH curve; and normal Ki NADPH. These two variants are clearly different from hitherto described G6PD variants, including the Japanese variants Gd(-) Heian and Gd(-) Kyoto. The mothers of both Gd(-) Tokushima and Gd(-) Tokoyo were found to be heterozygote by an ascorbate-cyanide test.

Direct-to-PCR tissue preservation for DNA profiling.

PubMed

Sorensen, Amy; Berry, Clare; Bruce, David; Gahan, Michelle Elizabeth; Hughes-Stamm, Sheree; McNevin, Dennis

2016-05-01

Disaster victim identification (DVI) often occurs in remote locations with extremes of temperatures and humidities. Access to mortuary facilities and refrigeration are not always available. An effective and robust DNA sampling and preservation procedure would increase the probability of successful DNA profiling and allow faster repatriation of bodies and body parts. If the act of tissue preservation also released DNA into solution, ready for polymerase chain reaction (PCR), the DVI process could be further streamlined. In this study, we explored the possibility of obtaining DNA profiles without DNA extraction, by adding aliquots of preservative solutions surrounding fresh human muscle and decomposing human muscle and skin tissue samples directly to PCR. The preservatives consisted of two custom preparations and two proprietary solutions. The custom preparations were a salt-saturated solution of dimethyl sulfoxide (DMSO) with ethylenediaminetetraacetic (EDTA) and TENT buffer (Tris, EDTA, NaCl, Tween 20). The proprietary preservatives were DNAgard (Biomatrica(®)) and Tissue Stabilising Kit (DNA Genotek). We obtained full PowerPlex(®) 21 (Promega) and GlobalFiler(®) (Life Technologies) DNA profiles from fresh and decomposed tissue preserved at 35 °C for up to 28 days for all four preservatives. The preservative aliquots removed from the fresh muscle tissue samples had been stored at -80 °C for 4 years, indicating that long-term archival does not diminish the probability of successful DNA typing. Rather, storage at -80 °C seems to reduce PCR inhibition.

Sample storage conditions significantly influence faecal microbiome profiles

PubMed Central

Choo, Jocelyn M; Leong, Lex EX; Rogers, Geraint B

2015-01-01

Sequencing-based studies of the human faecal microbiota are increasingly common. Appropriate storage of sample material is essential to avoid the introduction of post-collection bias in microbial community composition. Rapid freezing to −80 °C is commonly considered to be best-practice. However, this is not feasible in many studies, particularly those involving sample collection in participants’ homes. We determined the extent to which a range of stabilisation and storage strategies maintained the composition of faecal microbial community structure relative to freezing to −80 °C. Refrigeration at 4 °C, storage at ambient temperature, and the use of several common preservative buffers (RNAlater, OMNIgene.GUT, Tris-EDTA) were assessed relative to freezing. Following 72 hours of storage, faecal microbial composition was assessed by 16 S rRNA amplicon sequencing. Refrigeration was associated with no significant alteration in faecal microbiota diversity or composition. However, samples stored using other conditions showed substantial divergence compared to −80 °C control samples. Aside from refrigeration, the use of OMNIgene.GUT resulted in the least alteration, while the greatest change was seen in samples stored in Tris-EDTA buffer. The commercially available OMNIgene.GUT kit may provide an important alternative where refrigeration and cold chain transportation is not available. PMID:26572876

Sample storage conditions significantly influence faecal microbiome profiles.

PubMed

Choo, Jocelyn M; Leong, Lex E X; Rogers, Geraint B

2015-11-17

Sequencing-based studies of the human faecal microbiota are increasingly common. Appropriate storage of sample material is essential to avoid the introduction of post-collection bias in microbial community composition. Rapid freezing to -80 °C is commonly considered to be best-practice. However, this is not feasible in many studies, particularly those involving sample collection in participants' homes. We determined the extent to which a range of stabilisation and storage strategies maintained the composition of faecal microbial community structure relative to freezing to -80 °C. Refrigeration at 4 °C, storage at ambient temperature, and the use of several common preservative buffers (RNAlater, OMNIgene.GUT, Tris-EDTA) were assessed relative to freezing. Following 72 hours of storage, faecal microbial composition was assessed by 16 S rRNA amplicon sequencing. Refrigeration was associated with no significant alteration in faecal microbiota diversity or composition. However, samples stored using other conditions showed substantial divergence compared to -80 °C control samples. Aside from refrigeration, the use of OMNIgene.GUT resulted in the least alteration, while the greatest change was seen in samples stored in Tris-EDTA buffer. The commercially available OMNIgene.GUT kit may provide an important alternative where refrigeration and cold chain transportation is not available.

Study of DNA extraction methods for use in loop-mediated isothermal amplification detection of single resting cysts in the toxic dinoflagellates Alexandrium tamarense and A. catenella.

PubMed

Nagai, Satoshi; Yamamoto, Keigo; Hata, Naotugu; Itakura, Shigeru

2012-09-01

In a previous study, we experienced instable amplification and a low amplification success in loop-mediated isothermal amplification (LAMP) reactions from naturally occurring vegetative cells or resting cysts of the toxic dinoflagellates Alexandrium tamarense and Alexandrium catenella. In this study, we examined 4 methods for extracting DNA from single resting cysts of A. tamarense and A. catenella to obtain more stable and better amplification success and to facilitate unambiguous detection using the LAMP method. Apart from comparing the 4 different DNA extraction methods, namely, (1) boiling in Tris-EDTA (TE) buffer, (2) heating at 65 °C in hexadecyltrimethylammonium bromide buffer, (3) boiling in 0.5% Chelex buffer, and (4) boiling in 5% Chelex buffer, we also examined the need for homogenization to crush the resting cysts before DNA extraction in each method. Homogenization of resting cysts was found to be essential for DNA extraction in all 4 methods. The detection time was significantly shorter in 5% Chelex buffer than in the other buffers and the amplification success was 100% (65/65), indicating the importance of DNA extraction and the effectiveness of 5% Chelex buffer in the Alexandrium LAMP. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis, characterization and biological evaluation of novel α, β unsaturated amides.

PubMed

Esmailzadeh, K; Housaindokht, M R; Moradi, A; Esmaeili, A A; Sharifi, Z

2016-05-15

Three derivatives of α,β unsaturated amides have been successfully synthesized via Ugi-four component (U-4CR) reaction. The interactions of the amides with calf thymus deoxyribonucleic acid (ct-DNA) have been investigated in the Tris-HCl buffer (pH=7.4) using viscometric, spectroscopic, thermal denaturation studies, and also molecular docking. By UV-Vis absorption spectroscopy studies, adding CT-DNA to the compound solution caused the hypochromism indicates that there are interactions between the compounds and DNA base pairs. In competitive fluorescence with methylene blue as an intercalator probe, adding compounds to DNA-MB solution caused an increase in emission spectra of the complex. This could be because of compound replacing, with similar binding mode of MB, between the DNA base pairs due to release of bonded MB molecules from DNA-MB complex. Thermal denaturation studies and viscometric experiments also indicated that all three investigated compounds bind to CT-DNA by non-classical intercalation mode. Additionally, molecular docking technique predicted partial intercalation binding mode for the compounds. Also, the highest binding energy was obtained for compound 5a. These results are in agreement with results obtained by empirical methods. Copyright © 2016 Elsevier B.V. All rights reserved.

The behaviour of selected yttrium containing bioactive glass microspheres in simulated body environments.

PubMed

Cacaina, D; Ylänen, H; Simon, S; Hupa, M

2008-03-01

The study aims at the manufacture and investigation of biodegradable glass microspheres incorporated with yttrium potentially useful for radionuclide therapy of cancer. The glass microspheres in the SiO2-Na2O-P2O5-CaO-K2O-MgO system containing yttrium were prepared by conventional melting and flame spheroidization. The behaviour of the yttrium silicate glass microspheres was investigated under in vitro conditions using simulated body fluid (SBF) and Tris buffer solution (TBS), for different periods of time, according to half-life time of the Y-90. The local structure of the glasses and the effect of yttrium on the biodegradability process were evaluated by Fourier Transform Infrared (FT-IR) spectroscopy and Back Scattered Electron Imaging of Scanning Electron Microscopy (BEI-SEM) equipped with Energy Dispersive X-ray (EDX) analysis. UV-VIS spectrometry and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used for analyzing the release behaviour of silica and yttrium in the two used solutions. The results indicate that the addition of yttrium to a bioactive glass increases its structural stability which therefore, induced a different behaviour of the glasses in simulated body environments.

Buffer-free therapeutic antibody preparations provide a viable alternative to conventionally buffered solutions: from protein buffer capacity prediction to bioprocess applications.

PubMed

Bahrenburg, Sven; Karow, Anne R; Garidel, Patrick

2015-04-01

Protein therapeutics, including monoclonal antibodies (mAbs), have significant buffering capacity, particularly at concentrations>50 mg/mL. This report addresses pH-related issues critical to adoption of self-buffered monoclonal antibody formulations. We evaluated solution conditions with protein concentrations ranging from 50 to 250 mg/mL. Samples were both buffer-free and conventionally buffered with citrate. Samples were non-isotonic or adjusted for isotonicity with NaCl or trehalose. Studies included accelerated temperature stability tests, shaking stability studies, and pH changes in infusion media as protein concentrate is added. We present averaged buffering slopes of capacity that can be applied to any mAb and present a general method for calculating buffering capacity of buffer-free, highly concentrated antibody liquid formulations. In temperature stability tests, neither buffer-free nor conventionally buffered solution conditions showed significant pH changes. Conventionally buffered solutions showed significantly higher opalescence than buffer-free ones. In general, buffer-free solution conditions showed less aggregation than conventionally buffered solutions. Shaking stability tests showed no differences between buffer-free and conventionally buffered solutions. "In-use" preparation experiments showed that pH in infusion bag medium can rapidly approximate that of self-buffered protein concentrate as concentrate is added. In summary, the buffer capacity of proteins can be predicted and buffer-free therapeutic antibody preparations provide a viable alternative to conventionally buffered solutions. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biochemical characteristics of glucose-6-phosphate dehydrogenase variants among the Malays of Singapore with report of a new non-deficient (GdSingapore) and three deficient variants.

PubMed

Saha, N; Hong, S H; Wong, H A; Jeyaseelan, K; Tay, J S

1991-12-01

Biochemical characteristics of one non-deficient fast G6PD variant (GdSingapore) and six different deficient variants (three new, two Mahidol, one each of Indonesian and Mediterranean) were studied among the Malays of Singapore. The GdSingapore variant had normal enzyme activity (82%) and fast electrophoretic mobilities (140% in TEB buffer, 160% in phosphate and 140% in Tris-HCl buffer systems respectively). This variant is further characterized by normal Km for G6P; utilization of analogues (Gal6P, 2dG6P; dAmNADP), heat stability and pH optimum. The other six deficient G6PD variants had normal electrophoretic mobility in TEB buffer with enzyme activities ranging from 1 to 12% of GdB+. The biochemical characteristics identity them to be 2 Mahidol, 1 Indonesian and 1 Mediterranean variants and three new deficient variants.

[Indirect and repeated electromagnetic irradiation of extremely high freguency of bacteria Escherichia coli].

PubMed

Isakhanian, V; Trchunian, A

2005-01-01

It has been shown that separate irradiation of distilled water and tris-phosphate buffer containing some inorganic ions, with Escherichia coli K12 grown in anaerobic conditions upon fermentation of sugar (glucose) with "noise" electromagnetic radiation of extremely high frequencies (53.5-68 gHz) or millimeter waves (wavelength of 3 to 8 mm) with low flux capacity (0.01 mW) for 10, 30 and 60 min caused opposite effects, changing the growth of these bacteria. The irradiation of water has a bactericide effect, whereas the irradiation of the buffer stimulates bacterial growth although the buffer itself inhibits the growth. These results point out the role of water in the bactericide action of "noise" electromagnetic radiation of extremely high frequencies, and confirm the significance of membranotropic effects. The bactericide action disappeared after repeated irradiation for 10 and 30 min with 2-h intervals. This indicates the operation of some compensatory mechanisms in bacteria.

An Efficient Method for Co-purification of Eggshell Matrix Proteins OC-17, OC-116, and OCX-36

PubMed Central

2016-01-01

In this study, we improved the eggshell-membrane separation process by separating the shell and membrane with EDTA solution, evaluating effects of three different extraction solutions (acetic acid, EDTA, and phosphate solution), and co-purifying multiple eggshell proteins with two successive ion-exchange chromatography procedures (CM Sepharose Fast Flow and DEAE Sepharose Fast Flow). The recovery and residual rates of eggshell and membrane separated by the modified method with added EDTA solution were 93.88%, 91.15% and 1.01%, 2.87%, respectively. Ovocleidin-116 (OC-116) and ovocalyxin-36 (OCX-36) were obtained by loading 50 mM Na-Hepes, pH 7.5, 2 mM DTT and 350 mM NaCl buffer onto the DEAE-FF column at a flow rate of 1 mL/min, ovocleidin-17 (OC-17) was obtained by loading 100 mM NaCl, 50 mM Tris, pH 8.0 on the CM-FF column at a flow rate of 0.5 mL/min. The purities of OCX-36, OC-17 and OC-116 were 96.82%, 80.15% and 73.22%, and the recovery rates were 55.27%, 53.38% and 36.34%, respectively. Antibacterial activity test suggested that phosphate solution extract exhibited significantly higher activity against the tested bacterial strains than the acetic acid or EDTA extract, probably due to more types of proteins in the extract. These results demonstrate that this separation method is feasible and efficient. PMID:28115888

Preparation and Storage of High-Titer Lactic Streptococcus Bacteriophages1

PubMed Central

Nyiendo, J.; Seidler, Ramon J.; Sandine, W. E.; Elliker, P. R.

1974-01-01

Various techniques were employed for preparation of high-titer bacteriophage lysates of Streptococcus lactis, S. cremoris, and S. diacetilactis strains. Infection of a 4-h host culture in litmus milk at 30 C yielded the highest titers (2 × 109 to 4 × 1011 plaque-forming units/ml) for most phages. Host infection in lactose-containing broth produced similar virus numbers only when 0.1 M tris(hydroxymethyl)aminomethane buffer stabilized the pH. The pH at the time of infection as well as the inoculum phage titer were critical in obtaining high titers. Optimum conditions for infection in broth were coupled with a polyethylene glycol concentration procedure to routinely produce milligram quantities of phage from 1 liter of lysate. Neutralization of whey lysates, as a means of storage, offered no survival advantage over unneutralized samples. Storage of phage lysates in a 15% glycerol whey solution at -22 C yielded a high rate of survival in most cases, even with repeated freezing and thawing, over a period of 24 months. PMID:16349981

Spectroscopic analysis on the resveratrol-DNA binding interactions at physiological pH

NASA Astrophysics Data System (ADS)

Zhang, Shufang; Sun, Xuejun; Jing, Zhihong; Qu, Fengli

2011-11-01

The interaction of resveratrol with calf thymus deoxyribonucleic acid (ctDNA) under physiological conditions (Tris-HCl buffer solutions, pH 7.4) was studied by spectroscopy, fluorescence spectroscopy and viscosity measurement method, respectively. Results indicated that a complex of resveratrol with ctDNA was formed with a binding constant of K17 °C = 5.49 × 10 3 L mol -1 and K37 °C = 1.90 × 10 4 L mol -1. The fluorescence quenching mechanism of acridine orange (AO)-ctDNA by resveratrol was shown to be a static quenching type. The thermodynamic parameters of the complex were calculated by a double reciprocal method: ΔHms=4.64×10 J mol, ΔSms=231.8 J K mol and ΔGms=-2.54×10 J mol (37 °C). Spectroscopic techniques together with viscosity determination provided evidences of intercalation mode of binding for the interaction between resveratrol and ctDNA.

Investigating The Anti-apoptotic Effects of Shigella Flexneri Infection In Epithelial Cells

DTIC Science & Technology

2009-08-13

also been found in breast milk of convalescent mothers and most likely contribute to the reduction of disease severity in breast-fed infants (45...samples. Proteins were transferred to a nitrocellulose membrane and blocked with 5% dry milk in Tris-buffered saline (TBS). Caspases were detected by...dry milk overnight at 4°C. After washing, donkey anti- rabbit immunoglobulin G antibody conjugated to horseradish peroxidase (Amersham Biosciences

Myoinhibiting Peptides are the Ancestral Ligands of the Promiscuous Drosophila Sex Peptide Receptor

DTIC Science & Technology

2010-01-01

decreases the willingness to re-mate, induces egg production and egg laying, stimulates food intake, enhances antimicrobial peptide synthesis and reduces...polypropylene tubes, centrifuged to remove cell debris, and the supernatants dried. Each sample was dissolved in 250 ll of assay buffer (0.05 M Tris, 4...variations during the cDNA synthesis step, all RNA samples were reverse transcribed simultaneously. Furthermore, several negative control reactions, i.e

A Study of the 5S Ribosomal RNAs of the Vibrionaceae

DTIC Science & Technology

1984-01-01

codon (UAA, UAG, or UGA) TBE Tris-borate-EDTA buffer ug microgram, i.e., 10-’ gram 6 ul microliter. iJe., 10- 6 liter UPG unweighted pair-group UPGMA ...Psy~ww~w .......................... .. 4.------------------ 0 IC 5b. The UPGMA , or UPS average linkage, dendrogram resulting from the...cluster, and the V. damsela - Q. anguillarus doublet are identical to that predicted by UPGMA analysis. C. CONSERVED AND HYPERVARIABLE REGIONS As

Stress state during fixation determines susceptibility to fatigue-linked biodegradation in bioprosthetic heart valve materials.

PubMed

Margueratt, Sean D; Lee, J Michael

2002-01-01

Mechanical loading contributes to the structural deterioration of bioprosthetic heart valves. The influence of stress state during fixation may play a substantial role in their failure, linking fatigue damage caused by buckling and tension and the enzymatic degradation of glutaraldehyde-crosslinked collagen. Bovine pericardia were obtained immediately postmortem and 100 mm x 15 mm samples were cut in the base-to-apex direction. Half the samples were subjected to a uniaxial tensile stress of 250 kPa and half remained unloaded during a crosslinking treatment in 0.5% glutaraldehyde. Tissue samples were rinsed and cut into 16 mm x 4 mm test strips. Half of these strips were exposed to cyclic compressive buckling and alternating tension at 30 Hz for 20 million cycles (approx. 7.5 days) using a custom-built multi-sample fatigue system. Fatigue-damaged and non-damaged samples were subsequently incubated at 37 C for 48 hrs in: (i) Type I bacterial collagenase (20 U/ml) buffered in 0.05 M Tris, 10 mM CaCl2 2H2O (pH 7.4) or (ii) 0.05 M Tris buffer (pH 7.4) only. In both cases, the samples were loaded sinusoidally between 40 and 80 g using a previously described microtensile culture system. Tissue removed from the bath was rinsed in 0.1 M EDTA solution and mounted in a servo-hydraulic mechanical testing system (MTS). Ultimate tensile strength (UTS), maximum tissue modulus, and fracture strain were determined. The percent collagen solubilized was assessed by a colourmetric hydroxyproline assay of the enzyme bath and tissue sample. All data were analyzed by analysis of variance (ANOVA). The results confirmed the synergy between fatigue damage and collagenase proteolysis in these materials; however, there were no significant differences in this effect between simple fixation and stress-fixation up to 20 million cycles. There were significant decreases in the mechanical properties and an increase in the amount of collagen solubilized with increased exposure to fatigue cycling.

Denaturation of Proteins by SDS and by Tetra-alkylammonium Dodecyl Sulfates

PubMed Central

Lee, Andrew; Tang, Sindy K. Y.; Mace, Charles R.

2011-01-01

This paper describes the use of capillary electrophoresis (CE) to examine the influence of different cations (C+; C+ = Na+ and tetra-n-alkylammonium, NR4 +, where R = Me, Et, Pr, Bu) on the rates of denaturation of bovine carbonic anhydrase II (BCA) in the presence of the anionic surfactant dodecylsulfate (DS−). Analysis of the denaturation of BCA in solutions of Na+DS− and NR4 +DS− (in Tris-Gly buffer) indicated that the rates of formation of complexes of denatured BCA with DS− (BCAD-DS−n,sat) are indistinguishable and independent of the cation below the critical micellar concentration (cmc), and independent of the total concentration of DS− above the cmc. At concentrations of C+DS− above the cmc, BCA denatured with rates that depended on the cation; the rates decreased by a factor > 104, in the order Na+ ~ NMe4 + > NEt4 + > NPr4 + > NBu4 + – the same order as the values of cmc (which decrease from 4.0 mM for Na+DS− to 0.9 mM for NBu4 +DS− in Tris-Gly buffer). The relationship between values of cmc and rates of formation of BCAD-DS−n,sat suggested that the kinetics of denaturation of BCA involve the association of this protein with monomeric DS−, rather than with micelles of (C+DS−)n. A less-detailed survey of seven other proteins (α-lactalbumin, β-lactoglobulin A, β-lactoglobulin B, carboxypeptidase B, creatine phosphokinase, myoglobin, and ubiquitin) showed that the difference between Na+DS− and NR4 +DS− observed with BCA was not general. Instead, the influence of NR4 + on the association of DS− with these proteins depended on the protein. The selection of cation contributed to the properties (including composition, electrophoretic mobility, and partitioning behavior in aqueous two-phase systems) of aggregates of denatured protein and DS−. These results suggest that variation in the behavior of NR4 +DS− with changes in R may be exploited in methods for analyzing and separating mixtures of proteins. PMID:21834533

Denaturation of proteins by SDS and tetraalkylammonium dodecyl sulfates.

PubMed

Lee, Andrew; Tang, Sindy K Y; Mace, Charles R; Whitesides, George M

2011-09-20

This article describes the use of capillary electrophoresis (CE) to examine the influence of different cations (C(+); C(+) = Na(+) and tetra-n-alkylammonium, NR(4)(+), where R = Me, Et, Pr, and Bu) on the rates of denaturation of bovine carbonic anhydrase II (BCA) in the presence of anionic surfactant dodecylsulfate (DS(-)). An analysis of the denaturation of BCA in solutions of Na(+)DS(-) and NR(4)(+)DS(-) (in Tris-Gly buffer) indicated that the rates of formation of complexes of denatured BCA with DS(-) (BCA(D)-DS(-)(n,sat)) are indistinguishable and independent of the cation below the critical micellar concentration (cmc) and independent of the total concentration of DS(-) above the cmc. At concentrations of C(+)DS(-) above the cmc, BCA denatured at rates that depended on the cation; the rates decreased by a factor >10(4) in the order of Na(+) ≈ NMe(4)(+) > NEt(4)(+) > NPr(4)(+) > NBu(4)(+), which is the same order as the values of the cmc (which decrease from 4.0 mM for Na(+)DS(-) to 0.9 mM for NBu(4)(+)DS(-) in Tris-Gly buffer). The relationship between the cmc values and the rates of formation of BCA(D)-DS(-)(n,sat()) suggested that the kinetics of denaturation of BCA involve the association of this protein with monomeric DS(-) rather than with micelles of (C(+)DS(-))(n). A less-detailed survey of seven other proteins (α-lactalbumin, β-lactoglobulin A, β-lactoglobulin B, carboxypeptidase B, creatine phosphokinase, myoglobin, and ubiquitin) showed that the difference between Na(+)DS(-) and NR(4)(+)DS(-) observed with BCA was not general. Instead, the influence of NR(4)(+) on the association of DS(-) with these proteins depended on the protein. The selection of the cation contributed to the properties (including the composition, electrophoretic mobility, and partitioning behavior in aqueous two-phase systems) of aggregates of denatured protein and DS(-). These results suggest that the variation in the behavior of NR(4)(+)DS(-) with changes in R may be exploited in methods used to analyze and separate mixtures of proteins. © 2011 American Chemical Society

In vivo formation of mutagens by intraperitoneal administration of polycyclic aromatic hydrocarbons in animals during exposure to nitrogen dioxide.

PubMed

Miyanishi, K; Kinouchi, T; Kataoka, K; Kanoh, T; Ohnishi, Y

1996-07-01

Consumption of fossil fuels has increased indoor and outdoor concentrations of polycyclic aromatic hydrocarbons (PAHs) and nitrogen dioxide (NO2). To study the combined effect of PAH administration and NO2 exposure on mutagenicity of urine from animals we injected 400 mg/kg body wt i.p. one of five kinds of PAH (pyrene, fluoranthene, fluorene, anthracene and chrysene) into ICR mice, Wistar rats, Syrian golden hamsters or Hartley guinea pigs after exposure to 20 p.p.m. NO2 gas for 24 h and then exposed the animals to NO2 gas for an additional 24 h. During the latter 24 h we collected the urine and assayed its mutagenicity with the Ames Salmonella strains after treatment with beta-glucuronidase and arylsulfatase and extraction with dichloromethane. The urine from mice treated with both PAH and NO2 showed high mutagenicity for Salmonella typhimurium strains TA98 and TA100, whereas the urine from mice treated with PAH and air showed almost no mutagenic activity. The mutagenicity was decreased in nitroreductase- and acetyltransferase-deficient strains TA98NR and TA98/1,8-DNP6 respectively. Treatment with a mixture of 20% of each of the five kinds of PAH and NO2 augmented the urinary mutagenicity of mice 1.5-fold. The urine from hamsters treated with pyrene or fluoranthene and NO2 was also highly mutagenic, but that from rats or guinea pigs was not very mutagenic. The mutagenicity was also decreased in strains TA98NR and TA98/1,8-DNP6. These results suggest that the urine contains nitro compounds and that the nitration of PAHs occurs in the body of animals under exposure to NO2 gas. Actually, the nitrated metabolites of pyrene, 1-nitro-6/8-hydroxypyrene and 1-nitro-3-hydroxypyrene, were detected in the urine from mice treated with pyrene under exposure to NO2 gas. To elucidate the mechanism of in vivo nitration, NO2 (20 p.p.m.) was bubbled through 50 mM Tris-HCl buffer (pH 7.4) or dichloromethane solution containing pyrene or 1-hydroxypyrene (10 microg/ml). Pyrene was not nitrated by NO2 in either aqueous or organic solutions. However, 1-hydroxypyrene was changed to nitrohydroxypyrenes by NO2 in the Tris-HCl buffer, but not in the organic solution. Ascorbic acid, alpha-tocopherol, glutathione oleic acid and hemoglobin were found to inhibit the nitration of 1-hydroxypyrene in aqueous solution. The urinary mutagenicity of mice treated with both pyrene and NO2 was also decreased by oral administration of ascorbic acid and alpha-tocopherol. These results suggest that 1-hydroxypyrene is nitrated by an ionic reaction in the animal body after hydroxylation of pyrene in the liver.

Cold-induced ultrastructural changes in bull and boar sperm plasma membranes.

PubMed

De Leeuw, F E; Chen, H C; Colenbrander, B; Verkleij, A J

1990-04-01

The effect of low temperatures on the ultrastructure of the plasma membrane of bull and boar spermatozoa was investigated. Cold-induced changes in the organization of sperm plasma membrane components were demonstrated by the use of fast-freezing combined with freeze-fracture electron microscopy. This preparation technique ensures fixation without artifacts. At 38 degrees C bull and boar spermatozoa exhibited a random distribution of intramembranous particles over the plasma membrane of both head and tail. Exposure to 0 degree C resulted in redistribution of the intramembranous particles: on the head and principal piece of bull spermatozoa and on the principal piece of boar spermatozoa, particle-free areas were observed, whereas on the boar sperm head, particle aggregates were present. The original particle distribution was restored upon rewarming of bull and boar spermatozoa to 38 degrees C, as well as after freezing and thawing of bull spermatozoa. Dilution of bull and boar semen into Tris-dilution buffer and Beltsville Thaw Solution-dilution buffer, respectively, could not prevent cold-induced redistribution of intramembranous particles. The observed particle reorganization upon cooling was interpreted as the result of lateral phase separation in the plasma membrane. Species-dependent differences in cold-induced ultrastructural changes were considered to be determined by lipid composition and asymmetry of the plasma membrane, and might be related to differences in cold resistance between species.

Stability of sonicated aqueous suspensions of phospholipids under air.

PubMed

Almog, R; Forward, R; Samsonoff, C

1991-12-01

The stability of phospholipids in liposomal aqueous suspension against oxidative degradation in air was investigated using spectrophotometric indices, glutathione peroxidase reactivity and thin layer chromatography. Zwitterionic phospholipid was found to be susceptible to degradation via oxidation of polyunsaturated hydrocarbon chains and ester hydrolysis, producing oxidized lysophosphatide and free fatty acid derivatives. These products were characterized as hydroperoxides based on their reactivity with the selenium-dependent glutathione peroxidase isolated from human erythrocytes. Lecithin in Tris buffer was more resistant to hydrolysis than in water. The sonication of 8.0 mM of soybean phosphatidylcholine (SB-PC) suspension in 0.1 M Tris (pH 7.5) in the presence of air produced relatively high concentration of conjugated diene hydroperoxide, but a small amount of hydrolyzed products. Anionic phospholipids, such as egg-phosphatidylglycerol (egg-PG), demonstrated higher resistance to air oxidation than the zwitterionic lecithin, but its oxidation was promoted by sonication.

Influence of pH, buffers and role of quinolinic acid, a novel iron chelating agent, in the determination of hydroxyl radical scavenging activity of plant extracts by Electron Paramagnetic Resonance (EPR).

PubMed

Fadda, Angela; Barberis, Antonio; Sanna, Daniele

2018-02-01

The Fenton reaction is used to produce hydroxyl radicals for the evaluation of the antioxidant activity of plant extracts. In this paper the parameters affecting the production of hydroxyl radicals and their spin trapping with DMPO were studied. The use of quinolinic acid (Quin) as an Fe(II) ligand was proposed for antioxidant activity determination of Green tea, orange juice and asparagus extracts. Quin, buffers and pH affect the DMPO-OH signal intensity of the EPR spectra. Quin/Fe(II) and low pH enhance the OH generation. Phosphate and Tris-HCl buffers decrease the signal intensity measured in Fe(II)-sulfate and Fe(II)-Quin systems. The extracts were analyzed with Fenton systems containing Fe(II)-sulfate and Fe(II)-Quin with and without buffer. The highest activity was shown with Fe(II)-Quin without buffer, this system being less influenced by pH and chelating agents present in the extracts. This paper will help researchers to better design spin trapping experiments for food matrices. Copyright © 2017 Elsevier Ltd. All rights reserved.

Selective Permeation and Organic Extraction of Recombinant Green Fluorescent Protein (gfpuv) from Escherichia coli

PubMed Central

2002-01-01

Background Transformed cells of Escherichia coli DH5-α with pGFPuv, induced by IPTG (isopropyl-β-d-thiogalactopyranoside), express the green fluorescent protein (gfpuv) during growth phases. E. coli subjected to the combination of selective permeation by freezing/thawing/sonication cycles followed by the three-phase partitioning extraction (TPP) method were compared to the direct application of TPP to the same culture of E. coli on releasing gfpuv from the over-expressing cells. Material and Methods Cultures (37°C/100 rpm/ 24 h; μ = 0.99 h-1 - 1.10 h-1) of transformed (pGFP) Escherichia coli DH5-α, expressing the green fluorescent protein (gfpuv, absorbance at 394 nm and emission at 509 nm) were sonicated in successive intervals of sonication (25 vibrations/pulse) to determine the maximum amount of gfpuv released from the cells. For selective permeation, the transformed previously frozen (-75°C) cells were subjected to three freeze/thaw (-20°C/ 0.83°C/min) cycles interlaid by sonication (3 pulses/ 6 seconds/ 25 vibrations). The intracellular permeate with gfpuv in extraction buffer (TE) solution (25 mM Tris-HCl, pH 8.0, 1 mM β-mercaptoethanol β-ME, 0.1 mM PMSF) was subjected to the three-phase partitioning (TPP) method with t-butanol and 1.6 M ammonium sulfate. Sonication efficiency was verified on the application to the cells previously treated by the TPP method. The intra-cell releases were mixed and eluted through methyl HIC column with a buffer solution (10 mM Tris-HCl, 10 mM EDTA, pH 8.0). Results The sonication maximum released amount obtained from the cells was 327.67 μg gfpuv/mL (20.73 μg gfpuv/mg total proteins – BSA), after 9 min of treatment. Through the selective permeation by three repeated freezing/thawing/sonication cycles applied to the cells, a close content of 241.19 μg gfpuv/mL (29.74 μg gfpuv/mg BSA) was obtained. The specific mass range of gfpuv released from the same cultures, by the three-phase partitioning (TPP) method, in relation to total proteins, was higher, between 107.28 μg/mg and 135.10 μg/mg. Conclusions The selective permeation of gfpuv by freezing/thawing/sonication followed by TPP separation method was equivalent to the amount of gfpuv extracted from the cells directly by TPP; although selective permeation extracts showed better elution through the HIC column. PMID:11972900

IPE 7

NASA Technical Reports Server (NTRS)

1983-01-01

A description is given of the collection and treatment of samples of Prochloron cells. The cells of Prochloron were obtained and prepared in the following way. Colonies of the symbiotic host, the giant didemnid ascidian Lissoclinum patella, were collected at low-tide level on reef-flat sand between Kamori Island and Koror, Palau, Western Caroline Islands. The animal colonies were taken, immersed in sea water, to an 8,000-litre holding tank and kept with constantly running sea water at 30 deg. Individual colonies were picked clean of contaminants, rinsed in sea water buffered with 40 nM or 100 mM Tris buffer at pH 8.4, and squeezed by hand to express the algal cells from the cloacal atria. The algae were received in about an equal volume of the same buffered sea water; this neutralized the acids liberated by the bruised ascidians and thereby maintained the Ph high enough to keep the algal cells green. The Prochloron cells were washed twice with buffered sea water and concentrated by centrifugation at about 50 g for 90 seconds. Microscopic examination revealed that contamination by animal host cells or bacteria was negligible (much less than 1%).

sym-Trisubstituted 1,3,5-Triazine Derivatives as Promising Organic Corrosion Inhibitors for Steel in Acidic Solution.

PubMed

El-Faham, Ayman; Dahlous, Kholood A; Al Othman, Zeid A; Al-Lohedan, Hamad A; El-Mahdy, Gamal A

2016-03-31

Triazine derivatives, namely, 2,4,6-tris(quinolin-8-yloxy)-1,3,5-triazine (T3Q), N²,N⁴,N⁶-tris(pyridin-2-ylmethyl)-1,3,5-triazine-2,4,6-triamine (T3AMPy) and 2,2',2''-[(1,3,5-triazine-2,4,6-triyl)tris(azanediyl)] tris(ethan-1-ol) (T3EA) were synthesized and their inhibition of steel corrosion in hydrochloric acid solution was investigated using electrochemical techniques. The corrosion protection of the prepared compounds increased with increasing concentration and reached up to 98% at 250 ppm. The adsorption of T3Q, T3AMPy, and T3EA on the steel surface was in accordance with the Langmuir adsorption isotherm. The electrochemical results revealed that T3Q, T3AMPy and T3EA act as excellent organic inhibitors and can labeled as mixed type inhibitors. The efficiencies of the tested compounds were affected by the nature of the side chain present in the triazine ring, where T3EA gave the least inhibition while T3Q and T3AMPy gave higher and almost the same inhibition effects. The inhibition efficiencies obtained from the different electrochemical techniques were in good agreement.

A Bis-Triazacyclononane Tris-Pyridyl N9 -Azacryptand "Beer Can" Receptor for Complexation of Alkali Metal and Lead(II) Cations.

PubMed

Brown, Asha; Bunchuay, Thanthapatra; Crane, Christopher G; White, Nicholas G; Thompson, Amber L; Beer, Paul D

2018-04-18

A new bis-triazacyclononane tris-pyridyl N 9 -azacryptand ligand is prepared via a convenient one-pot [2+3] condensation reaction between triazacyclononane and 2,6-bis(bromomethyl) pyridine in the presence of M 2 CO 3 (M=Li, Na, K). The proton, lithium, sodium, potassium and lead(II) complexes of the ligand are characterised in the solid state. Preliminary solution-phase competition experiments indicate that the cryptand ligand preferentially binds lead(II) in the presence of sodium, calcium, potassium and zinc cations in methanol solution. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protection by Purines in Toxin Models of Parkinson’s Disease

DTIC Science & Technology

2013-07-01

non- fat dry milk in Tris buffered saline, 0.1% TWEEN-20). To detect urate transporter expression membranes were probed overnight with the following...11-1-0150 Annual Report (Year 2) 7 Fig 2. UOx protein in UBC-cre UOxflox/flox and control NTg UOxflox/flox mice treated with...UOx protein in liver was detected by Western blot. Band density was analyzed using Image J. Results were expressed as relative density to loading

Immobilisation of an antibacterial drug to Ti6Al4V components fabricated using selective laser melting

NASA Astrophysics Data System (ADS)

Vaithilingam, Jayasheelan; Kilsby, Samuel; Goodridge, Ruth D.; Christie, Steven D. R.; Edmondson, Steve; Hague, Richard J. M.

2014-09-01

Bacterial infections from biomedical implants and surgical devices are a major problem in orthopaedic, dental and vascular surgery. Although the sources of contaminations that lead to bacterial infections are known, it is not possible to control or avoid such infections completely. In this study, an approach to immobilise Ciprofloxacin® (an antibacterial drug) to phosphonic acid based self-assembled monolayers (SAMs) adsorbed on a selectively laser melted (SLM) Ti6Al4V structure, has been presented. X-ray photoelectron spectroscopy (XPS) and static water contact angle measurements confirmed the attachment of SAMs and the drug. Results showed that Ciprofloxacin® is highly stable under the oxidative conditions used in this study. In-vitro stability was estimated by immersing the Ciprofloxacin® immobilised substrates in 10 mM of Tris-HCl buffer (pH-7.4) for 42 days. The Tris-HCl buffer was analysed using UV-vis spectrophotometry at 7, 14, 28 and 42 day time intervals to determine the release of the immobilised drug. The drug was observed to release in a sustained manner. 50% of the drug was released after 4 weeks with approximately 40% of the drug remaining after 6 weeks. Antibacterial susceptibility tests revealed that the immobilised drug was therapeutically active upon its release. This study demonstrates the potential to use self-assembled monolayers to modify SLM fabricated surfaces with therapeutics.

Novel method of niosome generation using supercritical carbon dioxide part I: process mechanics.

PubMed

Wagner, Michael E; Rizvi, Syed S H

2015-01-01

A novel method for the production of non-ionic surfactant vesicles (niosomes) using an rapid expansion of supercritical solution (RESS)-based process coupled with a gas ejector is presented along with an investigation of parameters affecting niosome morphology, size and encapsulation efficiency of a 0.2 M D-glucose solution in Tris buffer at physiological pH. The solubility of the non-ionic surfactant polyoxyethylene(4) sorbitan monostearate in SC-CO2 was determined at three pressures (10, 15 and 20 MPa) and three temperatures (40, 50 and 60 °C). Mole fraction of Tween61 in the vapor phase increased with pressure at 40 °C, but did not change with pressure at 50 or 60 °C. Solubility data were correlated using the Peng-Robinson equation of state (PREOS) with the Panagiotopoulos and Reid mixing rule. Vesicles were either multilamellar or unilamellar, depending on the degree of precipitation of the lipid formulation at the point of aqueous cargo introduction. Vesicle particle size distributions were bimodal, with the 80-99% of the liposomal volume contributed niosomes ranging in size from 3 to 7 μm and the remaining niosomes ranging from 239 to 969 nm, depending on the system configuration. Encapsulation efficiency as high as 28% using the gas ejector to introduce the glucose cargo solution was achieved. Vesicle particle size and encapsulation efficiency were shown to be dependent on cargo droplet formation.

Striking Effects of Storage Buffers on Apparent Half-Lives of the Activity of Pseudomonas aeruginosa Arylsulfatase.

PubMed

Li, Yuwei; Yang, Xiaolan; Wang, Deqiang; Hu, Xiaolei; Yuan, Mei; Pu, Jun; Zhan, Chang-Guo; Yang, Zhaoyong; Liao, Fei

2016-08-01

To obtain the label enzyme for enzyme-linked-immunoabsorbent-assay of two components each time in one well with conventional microplate readers, molecular engineering of Pseudomonas aeruginosa arylsulfatase (PAAS) is needed. To compare thermostability of PAAS/mutants of limited purity, effects of buffers on the half-activity time (t 0.5) at 37 °C were tested. At pH 7.4, PAAS showed non-exponential decreases of activity, with the apparent t 0.5 of ~6.0 days in 50 mM HEPES, but ~42 days in 10 mM sodium borate with >85 % activity after 15 days; protein concentrations in both buffers decreased at slower rates after there were significant decreases of activities. Additionally, the apparent t 0.5 of PAAS was ~14 days in 50 mM Tris-HCl, and ~21 days in 10 mM sodium phosphate. By sodium dodecyl-polyacrylamide gel electrophoresis, the purified PAAS gave single polypeptide; after storage for 14 days at 37 °C, there were many soluble and insoluble fragmented polypeptides in the HEPES buffer, but just one principal insoluble while negligible soluble fragmented polypeptides in the borate buffer. Of tested mutants in the neutral borate buffer, rates for activity decreases and polypeptide degradation were slower than in the HEPES buffer. Hence, dilute neutral borate buffers were favorable for examining thermostability of PAAS/mutants.

Investigations of nanoscale variations in spin and charge transport in manganites and organic semiconductors using spin polarized scanning tunneling spectroscopy

NASA Astrophysics Data System (ADS)

Hughes, Cameron Richard

Analysis of DNA structure and behavior, up to and including full sequencing of a genome's bases, and of biological processes such as replication, transcription and translation, is essential for an understanding of genetic variation, heritable diseases and the effects of environmental factors. Recently, single-molecule techniques have been developed to study DNA properties in unprecedented detail. For a number of these techniques, controlled adsorption of linearly stretched DNA molecules on surfaces is necessary. In experiments where hybridization of adsorbed molecules to labeled probes is used to determine DNA structure, single-stranded DNA is needed. Conventionally, for long DNA's (up to Mbp), double-stranded DNA is deposited on a surface and denatured in-situ. While successful, this method has several disadvantages. This thesis reports efforts to directly adsorb long single-stranded DNA's out of solution as an alternative strategy. It consists of three parts: (1) Establishment of a simple method using Acridine Orange (AO) staining dye to determine whether DNA's are ss or ds on the surface. The method allows for the assessment of the degree of renaturation during deposition. Incubation of surface-adsorbed DNA in solutions of AO dye in the concentration range of 10--15uM were found to be effective for discriminating between ss DNA and ds DNA based on differences in the fluorescence emission spectra. (2) Deposition of ss DNA produced by heat denaturation on polymer-coated surfaces. Lambda DNA (48502bp) was adsorbed by drop evaporation or dipping/extraction of surface out of a buffered solution. The efficiency of deposition was optimized with respect to DNA concentration, buffer type and pH. (3) Separation of complementary single strands of Lambda, mono-cut digest and HindIII digest by gel electrophoresis. Using agarose gels in concentrations ranging from 0.4% to 1.4% (weight/volume), electric fields in the range 1--4V/cm in 1x Tris-Acetate-EDTA (TAE) buffer, good strand separation could be obtained. Both DC and pulsed electric fields were used and compared. Following separation, sense and anti-sense strands of lambda DNA were extracted from gels and deposited separately onto surfaces, and length distributions of the isolated molecules were measured by fluorescence microscopy.

The use of physiological solutions or media in calcium phosphate synthesis and processing.

PubMed

Tas, A Cuneyt

2014-05-01

This review examined the literature to spot uses, if any, of physiological solutions/media for the in situ synthesis of calcium phosphates (CaP) under processing conditions (i.e. temperature, pH, concentration of inorganic ions present in media) mimicking those prevalent in the human hard tissue environments. There happens to be a variety of aqueous solutions or media developed for different purposes; sometimes they have been named as physiological saline, isotonic solution, cell culture solution, metastable CaP solution, supersaturated calcification solution, simulated body fluid or even dialysate solution (for dialysis patients). Most of the time such solutions were not used as the aqueous medium to perform the biomimetic synthesis of calcium phosphates, and their use was usually limited to the in vitro testing of synthetic biomaterials. This review illustrates that only a limited number of research studies used physiological solutions or media such as Earle's balanced salt solution, Bachra et al. solutions or Tris-buffered simulated body fluid solution containing 27mM HCO3(-) for synthesizing CaP, and these studies have consistently reported the formation of X-ray-amorphous CaP nanopowders instead of Ap-CaP or stoichiometric hydroxyapatite (HA, Ca10(PO4)6(OH)2) at 37°C and pH 7.4. By relying on the published articles, this review highlights the significance of the use of aqueous solutions containing 0.8-1.5 mMMg(2+), 22-27mM HCO3(-), 142-145mM Na(+), 5-5.8mM K(+), 103-133mM Cl(-), 1.8-3.75mM Ca(2+), and 0.8-1.67mM HPO4(2-), which essentially mimic the composition and the overall ionic strength of the human extracellular fluid (ECF), in forming the nanospheres of X-ray-amorphous CaP. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Adherence of Enterohemorrhagic Escherichia coli to Human Epithelial Cells: The Role of Intimin

DTIC Science & Technology

1995-04-28

1994). Contamination of salad vegetables (Abdul-Raouf et al., 1993), raw milk (MacDonald et al., 1988), and unpasteurized apple cider (Besser et...membranes were blocked with 5% nonfat dried milk (Carnation Company, los Angeles, Cali!.) in Tris-buffered saline, pH 7.2 with 0.1% Tween-20 (v/v) (1B5-T...then ove~aid with a 1 :5000 dilution of either horseradish peroxidase-conjugated goat anti-mouse Ig (BMB), donkey anti-rabbit Ig (Amersham), or sheep

A Receptor-Coupled Evanescent Biosensor

DTIC Science & Technology

1990-05-01

fibers ....................................... 18 6. The effects of various concentrations of d-TC (0), carbamyl- choline (&), and a𔃾GT (0) on binding of...affinity gel washed with the homogenization buffer containing 0.1% Triton X-100. The affinity gel was then mixed with 50 mL of 1 M carbamy- choline for 4 h...at 23*C, then filtered, and the filtrate, containing carbamyl- choline and the nAChR protein, was dialyzed against 5 mM Tris pH 7.2 to remove the drug

Characterization of the Polypeptides in Varicella Zoster Virus - Infected Cells

DTIC Science & Technology

1984-03-16

DNA binding proteins.. 127 38. Autoradiogram of guanidine hydrochloride wash of DNA cellulose columns 129 Figure Page 32 39. Autoradiogram of P...of purification was seventy-fold 35 1^ with respect to host proteins and the S-methionine or G- glucosamine labeled virions were subjected to SDS... hydrochloride [pH7.5]. 20 mM EDTA, (2 x STE buffer), was used. For electron microscopy pellets were resuspended in 10 mM Tris- hydrochloride [pH 7.5]. 1 inM

Role of GGAP/PIKE-A in prostate cancer progression

DTIC Science & Technology

2009-05-01

linking alterations of GGAP2 activity to neo- plastic transformation. The GGAP2 locus at 12q13.3 is amplified in glioblastoma cell lines, primary glioma ...prostate cancer tissue lysates . Protein (1.5 mg of total) was incubated with anti-GGAP2 rabbit antibody and protein A agarose beads for 4 h before the...agarose pull-down assay. Purified proteins or cell lysates expressing wild-type and mutant GGAP2 were equilibrated in GTP binding buffer [20 mmol/L Tris

Surface functionalization of 3D glass-ceramic porous scaffolds for enhanced mineralization in vitro

NASA Astrophysics Data System (ADS)

Ferraris, Sara; Vitale-Brovarone, Chiara; Bretcanu, Oana; Cassinelli, Clara; Vernè, Enrica

2013-04-01

Bone reconstruction after tissue loosening due to traumatic, pathological or surgical causes is in increasing demand. 3D scaffolds are a widely studied solution for supporting new bone growth. Bioactive glass-ceramic porous materials can offer a three-dimensional structure that is able to chemically bond to bone. The ability to surface modify these devices by grafting biologically active molecules represents a challenge, with the aim of stimulating physiological bone regeneration with both inorganic and organic signals. In this research work glass ceramic scaffolds with very high mechanical properties and moderate bioactivity have been functionalized with the enzyme alkaline phosphatase (ALP). The material surface was activated in order to expose hydroxyl groups. The activated surface was further grafted with ALP both via silanization and also via direct grafting to the surface active hydroxyl groups. Enzymatic activity of grafted samples were measured by means of UV-vis spectroscopy before and after ultrasonic washing in TRIS-HCl buffer solution. In vitro inorganic bioactivity was investigated by soaking the scaffolds after the different steps of functionalization in a simulated body fluid (SBF). SEM observations allowed the monitoring of the scaffold morphology and surface chemical composition after soaking in SBF. The presence of ALP enhanced the in vitro inorganic bioactivity of the tested material.

A new capillary electrophoresis buffer for determining organic and inorganic anions in electroplating bath with surfactant additives.

PubMed

Sun, H; Lau, K M; Fung, Y S

2010-05-07

Monitoring of trace impurities in electroplating bath is needed to meet EU requirements for WEEE and RoHS and for quality control of electrodeposits. Methods using IC and 100% aqueous CE buffer were found producing non-repeatable results attributed to interference of surfactants and major methanesulphonate anion. A new CE buffer containing 1.5mM tetraethylenepentaamine, 3mM 1,3,5-benzenetricarboxylic acid and 15 mM Tris in 20% (v/v) methanol at pH=8.4 was shown to enhance the separation window, reduce interaction between buffer and bath constituents, and give satisfactory repeatability with baseline separation for 14 organic and inorganic anions within 14 min, good repeatability for migration time (0.32-0.57% RSD), satisfactory peak area and peak height (2.9-4.5 and 3-4.7% respectively), low detection limit (S/N=2, 20-150 ppb), and wide working ranges (0.1-100 ppm). The CE buffer with 20% (v/v) methanol has demonstrated its capability for identifying anion impurities causing problem in aged tin bath and the use of only 10-fold dilution to produce reliable results for quality assessment in plating bath containing high surfactant additives. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Facile and Stabile Linkages through Tyrosine: Bioconjugation Strategies with the Tyrosine-Click Reaction

PubMed Central

Ban, Hitoshi; Nagano, Masanobu; Gavrilyuk, Julia; Hakamata, Wataru; Inokuma, Tsubasa; Barbas, Carlos F.

2013-01-01

The scope, chemoselectivity, and utility of the click-like tyrosine labeling reaction with 4-phenyl-3H-1,2,4-triazoline-3,5(4H)-diones (PTADs) is reported. To study the utility and chemoselectivity of PTAD derivatives in peptide and protein chemistry, we synthesized PTAD derivatives possessing azide, alkyne, and ketone groups and studied their reactions with amino acid derivatives and peptides of increasing complexity. With proteins we studied the compatibility of the tyrosine click reaction with cysteine and lysine-targeted labeling approaches and demonstrate that chemoselective tri-functionalization of proteins is readily achieved. In particular cases, we noted PTAD decomposition resulted in formation of a putative isocyanate by-product that was promiscuous in labeling. This side reaction product, however, was readily scavenged by the addition of a small amount of 2-amino-2-hydroxymethyl-propane-1,3-diol (Tris) to the reaction medium. To study the potential of the tyrosine click reaction to introduce poly(ethylene) glycol chains onto proteins (PEGylation), we demonstrate that this novel reagent provides for the selective PEGylation of chymotrypsinogen whereas traditional succinimide-based PEGylation targeting lysine residues provided a more diverse range of PEGylated products. Finally, we applied the tyrosine click reaction to create a novel antibody drug conjugate. For this purpose, we synthesized a PTAD derivative linked to the HIV entry inhibitor aplaviroc. Labeling of the antibody trastuzumab with this reagent provided a labeled antibody conjugate that demonstrated potent HIV-1 neutralization activity demonstrating the potential of this reaction in creating protein conjugates with small molecules. The tyrosine click linkage demonstrated stability to extremes of pH, temperature and exposure to human blood plasma indicating that this linkage is significantly more robust than maleimide-type linkages that are commonly employed in bioconjugations. These studies support the broad utility of this reaction in the chemoselective modification of small molecules, peptides, and proteins under mild aqueous conditions over a broad pH range using a wide variety of biologically acceptable buffers such as phosphate buffered saline (PBS) and 2-amino-2-hydroxymethyl-propane-1,3-diol (Tris) buffers as well as others and mixed buffered compositions. PMID:23534985

Stabilization of Quinapril by Incorporating Hydrogen Bonding Interactions

PubMed Central

Roy, B. N.; Singh, G. P.; Godbole, H. M.; Nehate, S. P.

2009-01-01

In the present study stability of various known solvates of quinapril hydrochloride has been compared with nitromethane solvate. Nitromethane solvate was found to be more stable compared to other known solvates. Single crystal X-ray diffraction analysis of quinapril nitromethane solvate shows intermolecular hydrogen bonding between quinapril molecule and nitromethane. Stabilization of quinapril by forming strong hydrogen bonding network as in case of co-crystals was further studied by forming co-crystal with tris(hydroxymethyl)amino methane. Quinapril free base forms a stable salt with tris(hydroxymethyl)amino methane not reported earlier. Quinapril tris(hydroxymethyl)amino methane salt found to be stable even at 80° for 72 h i.e. hardly any formation of diketopiperazine and diacid impurity. As expected single crystal X-ray diffraction analysis reveals tris(hydroxymethyl)amino methane salt of quinapril shows complex hydrogen bonding network between the two entities along with ionic bond. The properties of this stable salt - stable in solid as well as solution phase, might lead to an alternate highly stable formulation. PMID:20502545

Analysis of the difference in color development in the dye-binding method due to the kind of buffer solution.

PubMed

Suzuki, Yuji

2006-06-01

In a dye-binding method using a pH indicator, color development has reportedly been affected by the kind of buffer solution used in the color reagent. This phenomenon was analyzed by using a calculation based on the assumption that the anion of the buffer solution also reacts with protein. Color development decreases with increases in the anion concentration of the buffer solution and in the equilibrium constant of the reaction between the anion and protein. The differences in color development due to the kind of buffer solution can be attributed to differences in the equilibrium constant of the reaction forming the anion-protein complex and to the concentration of the anion between the buffer solutions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winterbourn, C.C.; Sutton, H.C.

O2- was produced by gamma irradiation of formate solutions, by the action of xanthine oxidase on hypoxanthine and O2, and by the action of ferredoxin reductase on NADPH and paraquat in the presence of O2. Its reaction with H2O2 and various iron chelates was studied. Oxidation of deoxyribose to thiobarbituric acid-reactive products that was appropriately inhibited by OH. scavengers, or formate oxidation to CO2, was used to detect OH(.). With each source of O2-, and by these criteria, Fe(EDTA) efficiently catalyzed this (Haber-Weiss) reaction, but little catalysis was detectable with iron bound to DTPA, citrate, ADP, ATP, or pyrophosphate, ormore » without chelator in phosphate buffer. O2- produced from xanthine oxidase, but not from the other sources, underwent another iron-dependent reaction with H2O2, to produce an oxidant that did not behave as free OH(.). It was formed in phosphate or bicarbonate buffer, and caused deoxyribose oxidation that was readily inhibited by mannitol or Tris, but not by benzoate, formate, or dimethyl sulfoxide. It did not oxidize formate to CO2. Addition of EDTA changed the pattern of inhibition to that expected for a reaction of OH(.). The other chelators all inhibited deoxyribose oxidation, provided their concentrations were high enough. The results are compatible with iron bound to xanthine oxidase catalyzing production of a strong oxidant (which is not free OH.) from H2O2 and O2- produced by the enzyme.« less

Multivariate analysis for the optimization of microfluidics-assisted nanoprecipitation method intended for the loading of small hydrophilic drugs into PLGA nanoparticles.

PubMed

Chiesa, E; Dorati, R; Modena, T; Conti, B; Genta, I

2018-01-30

Design of Experiment-assisted evaluation of critical process (total flow rate, TFR, flow rate ratio, FRR) and formulation (polymer concentration and structure, drug:polymer ratio) variables in a novel microfluidics-based device, a staggered herringbone micromixer (SHM), for poly(lactic-co-glycolic acid) copolymer (PLGA) nanoparticles (NPs) manufacturing was performed in order to systematically evaluate and mathematically describe their effects on NPs sizes and drug encapsulation; a small hydrophilic moiety, N-acetylcysteine, was chosen as challenging model drug. SHM-assisted nanoprecipitation method consistently yielded NPs with tailor made sizes (in the range of 100-900 nm) and polydispersity index range from 0.061 to 0.286. Significant effects on NPs sizes were highlighted for TFR and FRR: increasing TFR (from 5 to 15 mL/min) and decreasing FRR (from 1:1 to 1:5 v/v, acetonitrile: buffer) NPs with mean diameter <200 nm were obtained. SHM technique allowed for flexible, application-specific tuning of PLGA NPs size using organic solvents with relatively low toxicity (acetone, acetonitrile), varying aqueous phase composition (Tris buffer vs PVA aqueous solution) and PLGA characteristics (Mw ranging from 25-90 kDa, capped or un-capped PLGA, different lactide:glycolide molar ratio). A very satisfactory N-Ac encapsulation efficiency (more than 67%) and a prolonged release (by 168 h) were achieved. Copyright © 2017 Elsevier B.V. All rights reserved.

Fluorescence Stability of Mercaptopropionic Acid Capped Cadmium Telluride Quantum Dots in Various Biochemical Buffers.

PubMed

Borse, Vivek; Kashikar, Adisha; Srivastava, Rohit

2018-04-01

Quantum dots are the semiconductor nanocrystals having unique optical and electronic properties. Quantum dots are category of fluorescent labels utilized for biological tagging, biosensing, bioassays, bioimaging and in vivo imaging as they exhibit very small size, signal brightness, photostability, tuning of light emission range, longer photoluminescence decay time as compared to organic dyes. In this work, we have synthesized and characterized mercaptopropionic acid capped cadmium telluride quantum dots (MPA-CdTe QDs) using hydrothermal method. The study further reports fluorescence intensity stability of quantum dots suspended in different buffers of varying concentration (1-100 mM), stored at various photophysical conditions. Fluorescence intensity values were reduced with increase in buffer concentration. When the samples were stored at room temperature in ambient light condition the quantum dots suspended in different buffers lost the fluorescence intensity after day 15 (except TRIS II). Fluorescence intensity values were found stable for more than 30 days when the samples were stored in dark condition. Samples stored in refrigerator displayed modest fluorescence intensity even after 300 days of storage. Thus, storage of MPA-CdTe QDs in refrigerator may be the suitable choice to maintain its fluorescence stability for longer time for further application.

Influence of strontium on structure, sintering and biodegradation behaviour of CaO-MgO-SrO-SiO2-P2O5-CaF2 glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goel, Ashutosh; Rajagopal, Raghu R.; Ferreira, Jose M.

The present study investigates the influence of SrO on structure, apatite forming ability, physico-chemical degradation and sintering behaviour of melt-quenched bioactive glasses with composition: mol.% (36.07 – x) CaO – x SrO - 19.24 MgO – 5.61 P2O5 – 38.49 SiO2 – 0.59 CaF2, where x varies between 0 – 10. The detailed structural analysis of glasses has been made by infra red spectroscopy (FTIR) and magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR). Silicon was predominantly present as Q2 (Si) species while phosphorus was found in orthophosphate type environment in all the investigated glasses. The apatite forming ability of glassesmore » was investigated by immersion of glass powders in simulated body fluid (SBF) for time durations varying between 1 h – 7 days. While increasing Sr2+/Ca2+ ratio in glasses did not affect the structure of glasses significantly, their apatite forming ability was decreased considerably. Further, physico-chemical degradation of glasses has been studied in accordance with ISO 10993-14 “Biological evaluation of medical devices – Part 14: Identification and quantification of degradation products from ceramics” in Tris HCl and citric acid buffer and the possible implications of ion release profile from glasses in different solutions has been discussed. The addition of strontium in glasses led to a 7-fold decrease in chemical degradation of glasses in Tris-HCl. The sintering of glass powders rendered glass-ceramics (GCs) with varying degree of crystallinity and good flexural strength (98-131 MPa) where the mechanical properties depend on the nature and amount of crystalline phases present in GCs.« less

Modulation of molecular hybridization and charge screening in a carbon nanotube network channel using the electrical pulse method.

PubMed

Woo, Jun-Myung; Kim, Seok Hyang; Chun, Honnggu; Kim, Sung Jae; Ahn, Jinhong; Park, Young June

2013-09-21

In this paper, we investigate the effect of electrical pulse bias on DNA hybridization events in a biosensor platform, using a Carbon Nanotube Network (CNN) and Gold Nano Particles (GNP) as an electrical channel. The scheme provides both hybridization rate enhancement of bio molecules, and electrical measurement in a transient state to avoid the charge screening effect, thereby significantly improving the sensitivity. As an example, the probe DNA molecules oscillate with pulse trains, resulting in the enhancement of DNA hybridization efficiency, and accordingly of the sensor performances in Tris-EDTA (TE) buffer solution, by as much as over three times, compared to the non-biasing conditions. More importantly, a wide dynamic range of 10(6) (target-DNA concentration from 5 pM to 5 μM) is achieved in human serum. In addition, the pulse biasing method enables one to obtain the conductance change, before the ions within the Electrical Double Layer (EDL) are redistributed, to avoid the charge screening effect, leading to an additional sensitivity enhancement.

Photocatalytic effect of anodic titanium oxide nanotubes on various cell culture media

NASA Astrophysics Data System (ADS)

Yu, Chun-Kang; Hu, Kan-Hung; Wang, Shing-Hoa; Hsu, Todd; Tsai, Huei-Ting; Chen, Chien-Chon; Liu, Shiu-Mei; Lin, Tai-Yuan; Chen, Chin-Hsing

2011-02-01

The use of titanium dioxide (TiO2) in photodynamic therapy for the treatment of cancer cells has been proposed following studies of cultured cancer cells. In this work, an ordered channel array of anodic titanium oxide (ATO) was fabricated by anodizing titanium foil. The ATO layer of nanotubes with diameters of 100 nm was made in NH4F electrolyte by anodization. The photocatalytic effect of ATO was examined on various culture media by ultraviolet A (UV-A) (366 nm) irradiation. After UV-A irradiation of the ATO layer, redox potential of Tris-HCl buffer (pH 7.5) and dilute acrylamide solution increased instantaneously. The redox potential of the serum-containing RPMI1640 medium also increased dramatically, while that of serum-containing MEM and DMEM media increased slightly. The UVA-induced high redox potential was correlated with the greater ability to break down plasmid DNA strands. These phenomena suggest that a culture medium, such as RPMI1640, with a greater ability to produce free radical may be associated with a stronger photocatalytic effect of ATO on cultured cancer cells reported previously.

DNA interaction studies of sesamol (3,4-methylenedioxyphenol) food additive.

PubMed

Kashanian, Soheila; Tahmasian Ghobadi, Ameneh; Roshanfekr, Hamideh; Shariati, Zohreh

2013-02-01

The interaction of native calf thymus DNA (CT-DNA) with sesamol (3,4-methylenedioxyphenol) in Tris-HCl buffer at neutral pH 7.4 was monitored by absorption spectrophotometry, viscometry and spectrofluorometry. It is found that sesamol molecules could interact with DNA outside and/or groove binding modes, as are evidenced by: hyperchromism in UV absorption band, very slow decrease in specific viscosity of DNA, and small increase in the fluorescence of methylene blue (MB)-DNA solutions in the presence of increasing amounts of sesamol, which indicates that it is able to partially release the bound MB. Furthermore, the enthalpy and entropy of the reaction between sesamol and CT-DNA showed that the reaction is enthalpy-favored and entropy-disfavored (ΔH = -174.08 kJ mol(-1); ΔS = -532.92 J mol(-1) K(-1)). The binding constant was determined using absorption measurement and found to be 2.7 × 10(4) M(-1); its magnitude suggests that sesamol interacts to DNA with a high affinity.

Fluorescence behaviour of 5,10-methenyltetrahydrofolate, 10-formyltetrahydrofolate, 10-formyldihydrofolate, and 10-formylfolate in aqueous solution at pH 8

NASA Astrophysics Data System (ADS)

Tyagi, A.; Penzkofer, A.; Batschauer, A.; Wolf, E.

2009-06-01

The fluorescence spectroscopic behaviour of (6R,S)-5,10-methenyltetrahydrofolate (MTHF), (6R,S)-10-formyltetrahydrofolate (10-HCO-H4folate), 10-formyldihydrofolate (10-HCO-H2folate), and 10-formylfolate (10-HCO-folate) in aqueous Tris-HCl buffer at pH 8 is studied. MTHF and 10-HCO-folate were commercially available. 10-HCO-H4folate was prepared from MTHF by hydrolysis at room temperature under anaerobic conditions. 10-HCO-H2folate was prepared by oxidation of 10-HCO-H4folate under aerobic conditions. Fluorescence quantum distributions at room temperature and fluorescence signal decays at room temperature and liquid nitrogen temperature were measured. The fluorescence lifetimes determined at room temperature (liquid nitrogen temperature) are 10 ps (2.9 ns) for MTHF, 38 ps (3.7 ns) for 10-HCO-H4folate, 80 ps (10.5 ns) for 10-HCO-H2folate, and 7.1 ns (20 ns) for 10-HCO-folate. The results are discussed in terms of dyadic (pterin-benzoyl-glutamate) photo-induced electron transfer and dyadic fluorescent dynamics.

Unanticipated coordination of tris buffer to the Radical SAM cluster of the RimO methylthiotransferase.

PubMed

Molle, Thibaut; Clémancey, Martin; Latour, Jean-Marc; Kathirvelu, Velavan; Sicoli, Giuseppe; Forouhar, Farhad; Mulliez, Etienne; Gambarelli, Serge; Atta, Mohamed

2016-07-01

Radical SAM enzymes generally contain a [4Fe-4S](2+/1+) (RS cluster) cluster bound to the protein via the three cysteines of a canonical motif CxxxCxxC. The non-cysteinyl iron is used to coordinate SAM via its amino-carboxylate moiety. The coordination-induced proximity between the cluster acting as an electron donor and the adenosyl-sulfonium bond of SAM allows for the homolytic cleavage of the latter leading to the formation of the reactive 5'-deoxyadenosyl radical used for substrate activation. Most of the structures of Radical SAM enzymes have been obtained in the presence of SAM, and therefore, little is known about the situation when SAM is not present. In this report, we show that RimO, a methylthiotransferase belonging to the radical SAM superfamily, binds a Tris molecule in the absence of SAM leading to specific spectroscopic signatures both in Mössbauer and pulsed EPR spectroscopies. These data provide a cautionary note for researchers who work with coordinative unsaturated iron sulfur clusters.

Intra-Accumbens Injection of a Dopamine Aptamer Abates MK-801-Induced Cognitive Dysfunction in a Model of Schizophrenia

PubMed Central

Holahan, Matthew R.; Madularu, Dan; McConnell, Erin M.; Walsh, Ryan; DeRosa, Maria C.

2011-01-01

Systemic administration of the noncompetitive NMDA-receptor antagonist, MK-801, has been proposed to model cognitive deficits similar to those seen in patients with schizophrenia. The present work investigated the ability of a dopamine-binding DNA aptamer to regulate these MK-801-induced cognitive deficits when injected into the nucleus accumbens. Rats were trained to bar press for chocolate pellet rewards then randomly assigned to receive an intra-accumbens injection of a DNA aptamer (200 nM; n = 7), tris buffer (n = 6) or a randomized DNA oligonucleotide (n = 7). Animals were then treated systemically with MK-801 (0.1 mg/kg) and tested for their ability to extinguish their bar pressing response. Two control groups were also included that did not receive MK-801. Data revealed that injection of Tris buffer or the random oligonucleotide sequence into the nucleus accumbens prior to treatment with MK-801 did not reduce the MK-801-induced extinction deficit. Animals continued to press at a high rate over the entire course of the extinction session. Injection of the dopamine aptamer reversed this MK-801-induced elevation in lever pressing to levels as seen in rats not treated with MK-801. Tests for activity showed that the aptamer did not impair locomotor activity. Results demonstrate the in vivo utility of DNA aptamers as tools to investigate neurobiological processes in preclinical animal models of mental health disease. PMID:21779401

Simultaneous pollutant removal and electricity generation in denitrifying microbial fuel cell with boric acid-borate buffer solution.

PubMed

Chen, Gang; Zhang, Shaohui; Li, Meng; Wei, Yan

2015-01-01

A double-chamber denitrifying microbial fuel cell (MFC), using boric acid-borate buffer solution as an alternative to phosphate buffer solution, was set up to investigate the influence of buffer solution concentration, temperature and external resistance on electricity generation and pollutant removal efficiency. The result revealed that the denitrifying MFC with boric acid-borate buffer solution was successfully started up in 51 days, with a stable cell voltage of 205.1 ± 1.96 mV at an external resistance of 50 Ω. Higher concentration of buffer solution favored nitrogen removal and electricity generation. The maximum power density of 8.27 W/m(3) net cathodic chamber was obtained at a buffer solution concentration of 100 mmol/L. An increase in temperature benefitted electricity generation and nitrogen removal. A suitable temperature for this denitrifying MFC was suggested to be 25 °C. Decreasing the external resistance favored nitrogen removal and organic matter consumption by exoelectrogens.

[Denaturation of egg antigens by cooking].

PubMed

Watanabe, Hiroko; Akaboshi, Chie; Sekido, Haruko; Tanaka, Kouki; Tanaka, Kazuko; Shimojo, Naoki

2012-01-01

Changes in egg protein contents by cooking were measured with an ELISA kit using Tris-HCl buffer in model foods including cake, meatballs, pasta and pudding made with whole egg, egg-white and egg-yolk. The egg protein contents were lowest in the deep-fried model foods of cakes and meatballs. Ovalbumin (OVA) was undetectable (<1 µg/g) and ovomucoid (OVM) was lowest in pouched meatballs, suggesting that processing temperature and uniform heat-treatment affect the detection of egg protein. Furthermore, egg protein contents were below 6 µg/g in the pouched meatballs and pasta made with egg-yolk, and OVA and OVM were not detected by Western blotting analysis with human IgE from patients' serum. On the other hand, processed egg proteins were detected with an ELISA kit using a surfactant and reductant in the extract buffer.

Expression of nattokinase in Escherichia coli and renaturation of its inclusion body.

PubMed

Ni, He; Guo, Peng-Cheng; Jiang, Wei-Ling; Fan, Xiao-Min; Luo, Xiang-Yu; Li, Hai-Hang

2016-08-10

Nattokinase is an important fibrinolytic enzyme with therapeutic applications for cardiovascular diseases. The full-length and mature nattokinase genes were cloned from Bacillus subtilis var. natto and expressed in pQE30 vector in Escherichia coli. The full-length gene expressed low nattokinase activity in the intracellular soluble and the medium fractions. The mature gene expressed low soluble nattokinase activity and large amount insoluble protein in inclusion bodies without enzyme activity. Large amount of refolding solutions (RSs) at different pH values were screening and RS-10 and RS-11 at pH 9 were selected to refold nattokinase inclusion bodies. The recombinant cells were lysed with 0.1mg/mL lysozyme and ultrasonic treatment. After centrifugation, the pellete was washed twice with 20mM Tris-HCl buffer (pH 7.5) containing 1% Triton X-100 to purify the inclusion bodies. The inclusion bodies were dissolved in water at pH 12.0 and refolded with RS-10. The refolded proteins showed 42.8IU/mg and 79.3IU/mg fibrinolytic activity by the traditional dilution method (20-fold dilution into RS-10) and the directly mixing the protein solution with equal volume RS-10, respectively, compared to the 52.0IU/mg of total water-soluble proteins from B. subtilis var. natto. This work demonstrated that the inclusion body of recombinant nattokinase expressed in E. coli could be simply refolded to the natural enzyme activity level by directly mixing the protein solution with equal volume refolding solution. Copyright © 2016 Elsevier B.V. All rights reserved.

Kinetics and mechanism of hydration of o-thioquinone methide in aqueous solution. Rate-determining protonation of sulfur.

PubMed

Chiang, Yvonne; Kresge, A Jerry; Sadovski, Oleg; Zhan, Hao-Qiang

2005-03-04

o-Thioquinone methide, 2, was generated in aqueous solution by flash photolysis of benzothiete, 1, and rates of hydration of this quinone methide to o-mercaptobenzyl alcohol, 3, were measured in perchloric acid solutions, using H2O and D2O as the solvent, and also in acetic acid and tris(hydroxymethyl)methylammonium ion buffers, using H2O as the solvent. The rate profiles constructed from these data show hydronium-ion-catalyzed and uncatalyzed hydration reaction regions, just like the rate profiles based on literature data for hydration of the oxygen analogue, o-quinone methide, of the presently examined substrate. Solvent isotope effects on hydronium-ion catalysis of hydration for the two substrates, however, are quite different: k(H)/k(D) = 0.42 for the oxygen quinone methide, whereas k(H)/k(D) = 1.66 for the sulfur substrate. The inverse nature (k(H)/k(D) < 1) of the isotope effect in the oxygen system indicates that this reaction occurs by a preequilibrium proton-transfer reaction mechanism, with protonation of the substrate on its oxygen atom being fast and reversible and capture of the benzyl-type carbocationic intermediate so formed being rate-determining. The normal direction (k(H)/k(D) > 1) of the isotope effect in the sulfur system, on the other hand, suggests that protonation of the substrate on its sulfur atom is in this case rate-determining, with carbocation capture a fast following step. A semiquantitative argument supporting this hypothesis is presented.

Analytical Measurement of Discrete Hydrogen Sulfide Pools in Biological Specimens

PubMed Central

Shen, Xinggui; Peter, Elvis A.; Bir, Shyamal; Wang, Rui; Kevil, Christopher G.

2015-01-01

Hydrogen sulfide (H2S) is a ubiquitous gaseous signaling molecule that plays a vital role in numerous cellular functions and has become the focus of many research endeavors including pharmaco-therapeutic manipulation. Amongst the challenges facing the field is the accurate measurement of biologically active H2S. We have recently reported that the typically used methylene blue method and its associated results are invalid and do not measure bonafide H2S. The complexity of analytical H2S measurement reflects the fact that hydrogen sulfide is a volatile gas and exists in the body in different forms, including a free form, an acid labile pool and as bound sulfane sulfur. Here we describe a new protocol to discretely measure specific H2S pools using the monobromobimane method coupled with RP-HPLC. This new protocol involves selective liberation, trapping and derivatization of H2S. Acid-labile H2S is released by incubating the sample in an acidic solution (pH 2.6) of 100 mM phosphate buffer with 0.1 mM DTPA, in an enclosed system to contain volatilized H2S. Volatilized H2S is then trapped in 100 mM Tris-HCl (pH 9.5, 0.1 mM DTPA) and then reacted with excess monobromobimane. In a separate aliquot, the contribution of bound sulfane sulfur pool was measured by incubating the sample with 1 mM TCEP (Tris(2-carboxyethyl)phosphine hydrochloride), a reducing agent to reduce disulfide bonds, in 100 mM phosphate buffer (pH 2.6, 0.1 mM DTPA), and H2S measurement performed in an analogous manner to the one described above. The acid labile pool was determined by subtracting the free hydrogen sulfide value from the value obtained by the acid liberation protocol. The bound sulfane sulfur pool was determined by subtracting the H2S measurement from the acid liberation protocol alone compared to that of TCEP plus acidic conditions. In summary, our new method protocol allows very sensitive and accurate measurement of the three primary biological pools of H2S including free, acid labile, and bound sulfane sulfur in various biological specimens. PMID:22561703

Aluminum elution and precipitation in glass vials: effect of pH and buffer species.

PubMed

Ogawa, Toru; Miyajima, Makoto; Wakiyama, Naoki; Terada, Katsuhide

2015-02-01

Inorganic extractables from glass vials may cause particle formation in the drug solution. In this study, the ability of eluting Al ion from borosilicate glass vials, and tendencies of precipitation containing Al were investigated using various pHs of phosphate, citrate, acetate and histidine buffer. Through heating, all of the buffers showed that Si and Al were eluted from glass vials in ratios almost the same as the composition of borosilicate glass, and the amounts of Al and Si from various buffer solutions at pH 7 were in the following order: citrate > phosphate > acetate > histidine. In addition, during storage after heating, the Al concentration at certain pHs of phosphate and acetate buffer solution decreased, suggesting the formation of particles containing Al. In citrate buffer, Al did not decrease in spite of the high elution amount. Considering that the solubility profile of aluminum oxide and the Al eluting profile of borosilicate glass were different, it is speculated that Al ion may be forced to leach into the buffer solution according to Si elution on the surface of glass vials. When Al ions were added to the buffer solutions, phosphate, acetate and histidine buffer showed a decrease of Al concentration during storage at a neutral range of pHs, indicating the formation of particles containing Al. In conclusion, it is suggested that phosphate buffer solution has higher possibility of forming particles containing Al than other buffer solutions.

Some characteristics of fructose 1,6-diphosphatase activity in rat liver

NASA Technical Reports Server (NTRS)

Ashman, P. U.; Lampkin, S. L.; Dillon, L.; Parks, R.

1974-01-01

A reliable assay for hepatic fructose 1,6-diphosphatase in the rat was developed. It was found that the greatest enzymic activity and highest protein levels were eluted from the colored portion of the homogenate. When the substrate concentration was 0.01M, the enzyme had optimal activity when incubated with 0.01M MgSO4 for 10 min. at 37 C in 0.05M Tris-HC1 buffer, pH 7.5. Specificity for the substrate, fructose 1,6-diphosphate, was obtained at substrate concentration of 0.01M.

A cost-effective device for the rapid transfer of gel-separated proteins onto membranes.

PubMed

Tam, Hann W; Huang, Yu-Chen; Tam, Ming F

2009-03-01

We describe here the fabrication of a cost-effective semi-dry blotting apparatus for the transfer of proteins onto membranes. Graphite sheets were used as electrodes. Protein mixtures were separated on NuPAGE 4% to 12% polyacrylamide gradient gels. With a Tris-bicine buffer, we demonstrated that close to 80% of the proteins with apparent molecular mass of 80kDa or less were removed from the gels after 8min of blotting. The process is much faster than the techniques reported previously in the literature.

Hepatocyte Growth Factor Inhibits Apoptosis by the Profibrotic Factor Angiotensin II via Extracellular Signal-regulated Kinase 1/2 in Endothelial Cells and Tissue Explants

DTIC Science & Technology

2010-12-01

were subjected to SDS- polyacryl - amide gel electrophoresis and electroblotted onto nitrocellulose membrane. Membranes were blocked with 5% bovine...1 mM sodium fluoride, 0.1 mM sodium orthovanadate, 1 mM tetrasodium pyrophosphate, 2 mM phenylmethylsulfonyl fluoride, 10 g/ml leupeptin, and 10 g...buffer [50 mM Tris-HCl, 1 mM EGTA, 1% (wt/vol) CHAPS, 10% glycerol, 50 mM sodium fluoride, 1 mM sodium orthovanadate, 2 mM phenylmethylsulfonyl fluoride

Identification of the Gene for Scleroderma in the Tsk/2 Mouse Strain: Implications for Human Scleroderma Pathogenesis and subset Distinctions

DTIC Science & Technology

2014-07-01

onto an 8% SDS gel. Proteins were transferred to a polyvinylidene fluoride membrane, blocked in 5% nonfat milk in Tris-buffered saline, probed with...a)marker)of)fibrosis)[3,)4]),)we)assessed)both) protein )and)mRNA)levels)in)fibroblasts)that)received)DNA)from)a) plasmid)containing)a)single)allele...of)a)single)Col3a1%gene.)In)three)independent)experiments,)COL1A1) protein ) was)significantly)elevated)after)48)hours)of)transfection)with)Col3a1Tsk2

Deregulation of miRNAs Contributes to Development and Progression of Prostate Cancer

DTIC Science & Technology

2011-09-01

blocking with 5% non- fat dry milk in Tris-buffered saline/0.05% Tween 20 (TBST), the membrane was incubated with a specific primary antibody...androgen R1881, and p53 protein was detected by Western blot analysis. Consistent with our previous observation (2), untreated LNCaP-R273H cells expressed...Cell Biochem 2009; 106(3): 363–371. 7 Appendices Figure 1. Western blot analysis of p53 protein in 5.0 nM R1881-treated LNCaP cells and LNCaP-R273H

Do Prostate Cancer Exosomes Generate a Field Effect Leading to Tumor Multifocality

DTIC Science & Technology

2016-04-01

ELEMENT NUMBER 6. AUTHOR(S) Marco Bisoffi 5d. PROJECT NUMBER 5e. TASK NUMBER E-Mail: bisoffi@chapman.edu 5f. WORK UNIT NUMBER 7... Sigma St. Louis MO. Plasmids were propagated in E. coli strain JM109 grown in LB broth containing 100ug/mL ampicillin and purified using spin column...buffer: 25 mM Tris, 8 mM MgCl2, 1 mM DTT, 15% glycerol, 1% TritonX-100, protease inhibitor cocktail ( Sigma St. Louis MO). Insoluble cell material was

The Role of Newly Discovered Exotoxin (S Toxin) in Pseudomonas aeruginosa Infections

DTIC Science & Technology

1979-08-01

sodium or potassium phosphate 6.0-8.0 N-2-hydroxyethylpiperazine-N’-2-ethanesulfonic acid (HEPES) 6.5-8.5 tris 7.0-9.5 sodium borate 7.5-9.5 sodium...was found to be variable with respect to whether sodium or potassium phosphate buffer was used. With sodium phosphate, virtually all the enzyme...activity bound was eluted between 20-100.2M phosphate at pH 6.8. With the potassium salt, elution occurs at 400-?00mM KP04. Since very little protein was

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sundaramurthi, Prakash; Suryanarayanan, Raj

To effectively inhibit succinate buffer crystallization and the consequent pH changes in frozen solutions. Using differential scanning calorimetry (DSC) and X-ray diffractometry (XRD), the crystallization behavior of succinate buffer in the presence of either (i) a crystallizing (glycine, mannitol, trehalose) or (ii) a non-crystallizing cosolute (sucrose) was evaluated. Aqueous succinate buffer solutions, 50 or 200 mM, at pH values 4.0 or 6.0 were cooled from room temperature to -25 C at 0.5 C/min. The pH of the solution was measured as a function of temperature using a probe designed to function at low temperatures. The final lyophiles prepared from thesemore » solutions were characterized using synchrotron radiation. When the succinic acid solution buffered to pH 4.0, in the absence of a cosolute, was cooled, there was a pronounced shift in the freeze-concentrate pH. Glycine and mannitol, which have a tendency to crystallize in frozen solutions, remained amorphous when the initial pH was 6.0. Under this condition, they also inhibited buffer crystallization and prevented pH change. At pH 4.0 (50 mM initial concentration), glycine and mannitol crystallized and did not prevent pH change in frozen solutions. While sucrose, a non-crystallizing cosolute, did not completely prevent buffer crystallization, the extent of crystallization was reduced. Sucrose decomposition, based on XRD peaks attributable to {beta}-D-glucose, was observed in frozen buffer solutions with an initial pH of 4.0. Trehalose completely inhibited crystallization of the buffer components when the initial pH was 6.0 but not at pH 4.0. At the lower pH, the crystallization of both trehalose dihydrate and buffer components was evident. When retained amorphous, sucrose and trehalose effectively inhibited succinate buffer component crystallization and the consequent pH shift. However, when trehalose crystallized or sucrose degraded to yield a crystalline decomposition product, crystallization of buffer was observed. Similarly, glycine and mannitol, two widely used bulking agents, inhibited buffer component crystallization only when retained amorphous. In addition to stabilizing the active pharmaceutical ingredient, lyoprotectants may prevent solution pH shift by inhibiting buffer crystallization.« less

Effect of L-aspartic acid on the growth, structure and spectral studies of Zinc (tris) Thiourea Sulphate (ZTS) single crystals

NASA Astrophysics Data System (ADS)

Samuel, Bincy Susan; Krishnamurthy, R.; Rajasekaran, R.

2014-11-01

Single crystals of pure and L-aspartic acid doped Zinc (Tris) Thiourea Sulphate (ZTS) were grown from aqueous solution by solution growth method. The cell parameters and structure of the grown crystals were determined by X-ray diffraction studies. The presence of functional group in the compound has been confirmed by FTIR and FT-Raman analysis. The optical transparency range has been studied through UV-Vis spectroscopy. TGA/DTA studies show thermal stability of the grown crystals. Microhardness study reveals that the hardness number (Hv) increases with load for pure and doped ZTS crystals. Dielectric studies have been carried out and the results are discussed. The second harmonic generation was confirmed for L-aspartic acid doped ZTS which is greater than pure ZTS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Pingrui; Liu, Ziyang; Liu, Dongyang

Pentacene organic thin-film transistors (OTFTs) were prepared by introducing 4, 4″-tris(3-methylphenylphenylamino) triphenylamine (m-MTDATA): MoO{sub 3}, Pentacene: MoO{sub 3}, and Pentacene: m-MTDATA: MoO{sub 3} as buffer layers. These OTFTs all showed significant performance improvement comparing to the reference device. Significantly, we observe that the device employing Pentacene: m-MTDATA: MoO{sub 3} buffer layer can both take advantage of charge transfer complexes formed in the m-MTDATA: MoO{sub 3} device and suitable energy level alignment existed in the Pentacene: MoO{sub 3} device. These two parallel paths led to a high mobility, low threshold voltage, and contact resistance of 0.72 cm{sup 2}/V s, −13.4 V,more » and 0.83 kΩ at V{sub ds} = − 100 V. This work enriches the understanding of MoO{sub 3} doped organic materials for applications in OTFTs.« less

Exposure to buffer solution alters tendon hydration and mechanics.

PubMed

Safa, Babak N; Meadows, Kyle D; Szczesny, Spencer E; Elliott, Dawn M

2017-08-16

A buffer solution is often used to maintain tissue hydration during mechanical testing. The most commonly used buffer solution is a physiological concentration of phosphate buffered saline (PBS); however, PBS increases the tissue's water content and decreases its tensile stiffness. In addition, solutes from the buffer can diffuse into the tissue and interact with its structure and mechanics. These bathing solution effects can confound the outcome and interpretation of mechanical tests. Potential bathing solution artifacts, including solute diffusion, and their effect on mechanical properties, are not well understood. The objective of this study was to measure the effects of long-term exposure of rat tail tendon fascicles to several concentrations (0.9-25%) of NaCl, sucrose, polyethylene glycol (PEG), and SPEG (NaCl+PEG) solutions on water content, solute diffusion, and mechanical properties. We found that with an increase in solute concentration the apparent water content decreased for all solution types. Solutes diffused into the tissue for NaCl and sucrose, however, no solute diffusion was observed for PEG or SPEG. The mechanical properties changed for both NaCl solutions, in particular after long-term (8h) incubation the modulus and equilibrium stress decreased compared to short-term (15min) for 25% NaCl, and the cross sectional area increased for 0.9% NaCl. However, the mechanical properties were unchanged for both PEG and SPEG except for minor alterations in stress relaxation parameters. This study shows that NaCl and sucrose buffer solutions are not suitable for long-term mechanical tests. We therefore propose using PEG or SPEG as alternative buffer solutions that after long-term incubation can maintain tissue hydration without solute diffusion and produce a consistent mechanical response. Copyright © 2017 Elsevier Ltd. All rights reserved.

Addition of zinc methacrylate in dental polymers: MMP-2 inhibition and ultimate tensile strength evaluation.

PubMed

Henn, Sandrina; de Carvalho, Rodrigo Varella; Ogliari, Fabrício Aulo; de Souza, Ana Paula; Line, Sergio Roberto Peres; da Silva, Adriana Fernandes; Demarco, Flávio Fernando; Etges, Adriana; Piva, Evandro

2012-04-01

This study evaluated the effect of zinc methacrylate (ZM) on the inhibition of matrix metalloproteinase 2 (MMP-2) and the ultimate tensile strength (UTS) of an experimental polymer. Enzymes secreted from mouse gingival tissues were analyzed by gelatin zymography in buffers containing 5 mM CaCl(2) (Tris-CaCl(2)) in 50 mM Tris-HCl buffer with various concentrations of ZM (0.5, 1, 2, 4, 8, and 16 mM). The matrix metalloproteinases present in the conditioned media were characterized by immunoprecipitation. The polymer UTS evaluation was performed in eight groups with various concentrations of ZM (0, 0.5, 1, 2.5, 5, 10, 20, and 30 wt.%), in a mechanical testing machine. MMP-2 (62 kDa) was detected in the zymographic assays and inhibited by ZM in all tested concentrations. UTS data were submitted to one-way ANOVA and Tukey's test (α = 0.05), and no significant differences were observed among groups, except in the polymer containing 30% ZM, presenting a significantly lower value when compared with the control group (p < 0.05). The results suggest that ZM inhibits MMP-2 expression in all concentrations tested, while small concentrations did not affect the ultimate tensile strength of the polymer. Zinc methacrylate is a metalloproteinase inhibitor that can be copolymerized with other methacrylate monomers. Yet, the addition of ZM did not affect the resin bond strength. Thus, in vivo tests should be performed to evaluate the performance of this material.

Identification of different domains of calpain and calpastatin from chicken blood and their role in post-mortem aging of meat during holding at refrigeration temperatures.

PubMed

Biswas, A K; Tandon, S; Beura, C K

2016-06-01

The aim of this study was to develop a simple, specific and rapid analytical method for accurate identification of calpain and calpastatin from chicken blood and muscle samples. The method is based on liquid-liquid extraction technique followed by casein Zymography detection. The target compounds were extracted from blood and meat samples by tris buffer, and purified and separated on anion exchange chromatography. It has been observed that buffer (pH 6.7) containing 50 mM tris-base appears to be excellent extractant as activity of analytes was maximum for all samples. The concentrations of μ-, m-calpain and calpastatin detected in the extracts of blood, breast and thigh samples were 0.28-0.55, 1.91-2.05 and 1.38-1.52 Unit/g, respectively. For robustness, the analytical method was applied to determine the activity of calpains (μ and m) in eighty postmortem muscle samples. It has been observed that μ-calpain activity in breast and thigh muscles declined very rapidly at 48 h and 24 h, respectively while activity of m-calpain remained stable. Shear force values were also declined with the increase of post-mortem aging showing the presence of ample tenderness of breast and thigh muscles. Finally, it is concluded that the method standardized for the detection of calpain and calpastatin has the potential to be applied to identify post-mortem aging of chicken meat samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Solvent selection and optimization of α-chymotrypsin-catalyzed synthesis of N-Ac-Phe-Tyr-NH2 using mixture design and response surface methodology.

PubMed

Hu, Shih-Hao; Kuo, Chia-Hung; Chang, Chieh-Ming J; Liu, Yung-Chuan; Chiang, Wen-Dee; Shieh, Chwen-Jen

2012-01-01

A peptide, N-Ac-Phe-Tyr-NH(2) , with angiotensin I-converting enzyme (ACE) inhibitor activity was synthesized by an α-chymotrypsin-catalyzed condensation reaction of N-acetyl phenylalanine ethyl ester (N-Ac-Phe-OEt) and tyrosinamide (Tyr-NH(2) ). Three kinds of solvents: a Tris-HCl buffer (80 mM, pH 9.0), dimethylsulfoxide (DMSO), and acetonitrile were employed in this study. The optimum reaction solvent component was determined by simplex centroid mixture design. The synthesis efficiency was enhanced in an organic-aqueous solvent (Tris-HCl buffer: DMSO: acetonitrile = 2:1:1) in which 73.55% of the yield of N-Ac-Phe-Tyr-NH(2) could be achieved. Furthermore, the effect of reaction parameters on the yield was evaluated by response surface methodology (RSM) using a central composite rotatable design (CCRD). Based on a ridge max analysis, the optimum condition for this peptide synthesis included a reaction time of 7.4 min, a reaction temperature of 28.1°C, an enzyme activity of 98.9 U, and a substrate molar ratio (Phe:Tyr) of 1:2.8. The predicted and the actual (experimental) yields were 87.6 and 85.5%, respectively. The experimental design and RSM performed well in the optimization of synthesis of N-Ac-Phe-Tyr-NH(2) , so it is expected to be an effective method for obtaining a good yield of enzymatic peptide. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

40 CFR 721.4100 - Tris(disubstituted alkyl) het-er-o-cy-cle.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for... substance is present in a plastic, an elastomer, a rubber matrix, or in a solution. (iii) Industrial... substance imported in a plastic, an elastomer, a rubber matrix, or in a solution, such that inhalation is...

40 CFR 721.4100 - Tris(disubstituted alkyl) het-er-o-cy-cle.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for... substance is present in a plastic, an elastomer, a rubber matrix, or in a solution. (iii) Industrial... substance imported in a plastic, an elastomer, a rubber matrix, or in a solution, such that inhalation is...

Formate binding near the redox-active tyrosineD in photosystem II: consequences on the properties of tyrD.

PubMed

Hienerwadel, Rainer; Gourion-Arsiquaud, Samuel; Ballottari, Matteo; Bassi, Roberto; Diner, Bruce A; Berthomieu, Catherine

2005-06-01

Formate and phosphate affect substantially the rate of tyrosine D (TyrD) oxidation and the stability of the radical TyrD* in Photosystem II [Hienerwadel R, Boussac A, Breton J and Berthomieu C (1996) Biochemistry 35: 15447-15460]. This observation prompted us to analyze the influence of formate and phosphate on the environment of TyrD using FTIR spectroscopy. The nu (CO) IR mode of TyrD* at 1503 cm-1 remains unchanged whatever the buffer used at pH 6 and whether formate is present or not in the sample. Similarly, the main IR mode of reduced TyrD remains at approximately 1250 cm-1 in all tested conditions. We thus conclude that formate does not modify the hydrogen-bonded interactions of TyrD and TyrD* with neighbouring D2His189 and D2Gln164. In the TyrD-state, an IR mode of formate significantly different from that observed in solution, is detected using 13C-formate, showing that formate forms a strong electrostatic interaction within PS II. The presence of formate affects also IR bands that may be assigned to an arginine side chain. Upon TyrD* formation, formate does not protonate but its binding interaction weakens. A proton uptake by Mes or phosphate buffer is detected, which is not observed when BisTris is used as a buffer. In these latter conditions, IR bands characteristic of the protonation of a carboxylate group of the protein are detected instead. The present IR data and the recent structural model of the TyrD environment proposed by Ferreira KN, Iverson TM, Maghlaoui K, Barber J and Iwata S [(2004) Science 303: 1831-1838], suggest that the proton released upon TyrD* formation is shared within a hydrogen bonding network including D2Arg294, and CP47Glu364 and that perturbation of this network by formate - possibly binding near D2Arg294 - substantially affects the properties of TyrD.

Tris-amidoximate uranyl complexes via η2 binding mode coordinated in aqueous solution shown by X-ray absorption spectroscopy and density functional theory methods.

PubMed

Zhang, Linjuan; Qie, Meiying; Su, Jing; Zhang, Shuo; Zhou, Jing; Li, Jiong; Wang, Yu; Yang, Shitong; Wang, Shuao; Li, Jingye; Wu, Guozhong; Wang, Jian Qiang

2018-03-01

The present study sheds some light on the long-standing debate concerning the coordination properties between uranyl ions and the amidoxime ligand, which is a key ingredient for achieving efficient extraction of uranium. Using X-ray absorption fine structure combined with theoretical simulation methods, the binding mode and bonding nature of a uranyl-amidoxime complex in aqueous solution were determined for the first time. The results show that in a highly concentrated amidoxime solution the preferred binding mode between UO 2 2+ and the amidoxime ligand is η 2 coordination with tris-amidoximate species. In such a uranyl-amidoximate complex with η 2 binding motif, strong covalent interaction and orbital hybridization between U 5f/6d and (N, O) 2p should be responsible for the excellent binding ability of the amidoximate ligand to uranyl. The study was performed directly in aqueous solution to avoid the possible binding mode differences caused by crystallization of a single-crystal sample. This work also is an example of the simultaneous study of local structure and electronic structure in solution systems using combined diagnostic tools.

Method for Detection and Enumeration of Cryptosporidium parvum Oocysts in Feces, Manures, and Soils

PubMed Central

Kuczynska, Ewa; Shelton, Daniel R.

1999-01-01

Eight concentration and purification methods were evaluated to determine percentages of recovery of Cryptosporidium parvum oocysts from calf feces. The NaCl flotation method generally resulted in the highest percentages of recovery. Based on the percentages of recovery, the amounts of fecal debris in the final oocyst preparations, the relatively short processing time (<3 h), and the low expense, the NaCl flotation method was chosen for further evaluation. Extraction efficiency was evaluated by using oocyst concentrations of 25, 50, 102, 103, 104, and 105 oocysts g of bovine feces−1. The percentages of recovery ranged from 10.8% (25 oocysts g−1) to 17.0% (104 oocysts g−1) (r2 = 0.996). A conservative estimate of the detection limit for bovine feces is ca. 30 oocysts g of feces−1. Percentages of recovery were determined for six different types of animal feces (cow, horse, pig, sheep, deer, and chicken feces) at a single oocyst concentration (104 oocysts g−1). The percentages of recovery were highest for bovine feces (17.0%) and lowest for chicken feces (3.2%). Percentages of recovery were determined for bovine manure after 3 to 7 days of storage. The percentages of recovery ranged from 1.9 to 3.5% depending on the oocyst concentration, the time of storage, and the dispersing solution. The percentages of oocyst recovery from soils were evaluated by using different flotation solutions (NaCl, cold sucrose, ZnSO4), different dispersing solutions (Triton X-100, Tween 80, Tris plus Tween 80), different dispersion techniques (magnetic stirring, sonication, blending), and different dispersion times (5, 15, and 30 min). Twenty-five-gram soil samples were used to reduce the spatial variability. The highest percentages of recovery were obtained when we used 50 mM Tris–0.5% Tween 80 as the dispersing solution, dispersion for 15 min by stirring, and saturated NaCl as the flotation solution. The percentages of oocyst recovery from freshly spiked sandy loam, silty clay loam, and clay loam soils were ca. 12 to 18, 8, and 6%, respectively. The theoretical detection limits were ca. 1 to 2 oocysts g of soil−1 depending on the soil type. The percentages of recovery without dispersant (distilled H2O or phosphate-buffered saline) were less than 0.1%, which indicated that oocysts adhere to soil particles. The percentages of recovery decreased with storage time, although the addition of dispersant (Tris-Tween 80) before storage appeared to partially prevent adhesion. These data indicate that the NaCl flotation method is suitable for routine detection and enumeration of oocysts from feces, manures, soils, or soil-manure mixtures. PMID:10388670

Variation of power generation at different buffer types and conductivities in single chamber microbial fuel cells.

PubMed

Nam, Joo-Youn; Kim, Hyun-Woo; Lim, Kyeong-Ho; Shin, Hang-Sik; Logan, Bruce E

2010-01-15

Microbial fuel cells (MFCs) are operated with solutions containing various chemical species required for the growth of electrochemically active microorganisms including nutrients and vitamins, substrates, and chemical buffers. Many different buffers are used in laboratory media, but the effects of these buffers and their inherent electrolyte conductivities have not been examined relative to current generation in MFCs. We investigated the effect of several common buffers (phosphate, MES, HEPES, and PIPES) on power production in single chambered MFCs compared to a non-buffered control. At the same concentrations the buffers produced different solution conductivities which resulted in different ohmic resistances and power densities. Increasing the solution conductivities to the same values using NaCl produced comparable power densities for all buffers. Very large increases in conductivity resulted in a rapid voltage drop at high current densities. Our results suggest that solution conductivity at a specific pH for each buffer is more important in MFC studies than the buffer itself given relatively constant pH conditions. Based on our analysis of internal resistance and a set neutral pH, phosphate and PIPES are the most useful buffers of those examined here because pH was maintained close to the pK(a) of the buffer, maximizing the ability of the buffer to contribute to increase current generation at high power densities. Copyright 2009 Elsevier B.V. All rights reserved.

Enhancing recovery of recombinant hepatitis B surface antigen in lab-scale and large-scale anion-exchange chromatography by optimizing the conductivity of buffers.

PubMed

Mojarrad Moghanloo, Gol Mohammad; Khatami, Maryam; Javidanbardan, Amin; Hosseini, Seyed Nezamedin

2018-01-01

In biopharmaceutical science, ion-exchange chromatography (IEC) is a well-known purification technique to separate the impurities such as host cell proteins from recombinant proteins. However, IEC is one of the limiting steps in the purification process of recombinant hepatitis B surface antigen (rHBsAg), due to its low recovery rate (<50%). In the current study, we hypothesized that ionic strengths of IEC buffers are easy-to-control parameters which can play a major role in optimizing the process and increasing the recovery. Thus, we investigated the effects of ionic strengths of buffers on rHBsAg recovery via adjusting Tris-HCl and NaCl concentrations. Increasing the conductivity of equilibration (Eq.), washing (Wash.) and elution (Elut.) buffers from their initial values of 1.6 mS/cm, 1.6 mS/cm, and 7.0 mS/cm to 1.6 mS/cm, 7 mS/cm and 50 mS/cm, respectively yielded an average recovery rate of 82% in both lab-scale and large-scale weak anion-exchange chromatography without any harsh effect on the purity percentage of rHBsAg. The recovery enhancement via increasing the conductivity of Eq. and Wash. buffers can be explained by their roles in reducing the binding strength and aggregation of retained particles in the column. Moreover, further increase in the salt concentration of Elut. Buffer could substantially promote the ion exchange process and the elution of retained rHBsAg. Copyright © 2017 Elsevier Inc. All rights reserved.

Ligase Detection Reaction for the Analysis of Point Mutations using Free Solution Conjugate Electrophoresis in a Polymer Microfluidic Device

PubMed Central

Sinville, Rondedrick; Coyne, Jennifer; Meagher, Robert J.; Cheng, Yu-Wei; Barany, Francis; Barron, Annelise; Soper, Steven A.

2010-01-01

We have developed a new method for the analysis of low abundant point mutations in genomic DNA using a combination of an allele-specific ligase detection reaction (LDR) with free-solution conjugate electrophoresis (FSCE) to generate and analyze the genetic products. FSCE eliminates the need for a polymer sieving matrix by conjugating chemically synthesized polyamide “drag-tags” onto the LDR primers. The additional drag of the charge-neutral drag-tag breaks the linear scaling of the charge-to-friction ratio of DNA and enables size-based separations of DNA in free solution using electrophoresis with no sieving matrix. We successfully demonstrate the conjugation of polyamide drag-tags onto a set of four LDR primers designed to probe the K-ras oncogene for mutations highly associated with colorectal cancer, the simultaneous generation of fluorescently-labeled LDR/drag-tagged (LDR-dt) products in a multiplexed, single-tube format with mutant:wild-type ratios as low as 1:100, respectively, and the single-base, high-resolution separation of all four LDR-dt products. Separations were conducted in free solution with no polymer network using both a commercial capillary array electrophoresis (CAE) system and a poly(methylmethacrylate), PMMA, microchip replicated via hot-embossing with only a Tris-based running buffer containing additives to suppress the electroosmotic flow (EOF). Typical analysis times for LDR-dt conjugates were 11 min using the CAE system and as low as 85 s for the PMMA microchips. With resolution comparable to traditional gel-based CAE, FSCE along with microchip electrophoresis decreased the separation time by more than a factor of 40. PMID:19053073

Pleiotrophin as a Growth Factor and Therapeutic Target in Breast Cancer

DTIC Science & Technology

1997-10-01

novel phospholipase A2 related gene. Nucl Acid Res 21:135-143. 11. Gattoni-Celli, S., K . Kirsch, S. Kalled , and K . J. Isselbacher. 1986. Expression...clone (G11-F7) is enlarged. Genomic Southern blot probes (a,b,c) and restriction sites are shown (B=BamHI, H=HindIII, Sc=ScaI, K =KpnI). 10WJ 3fr 4&V...otherwise in 25 mM Tris pH8.3/200 mM glycine/20% methanol. The membrane was blocked in PBS (phospate-buffered saline )/0.1% Tween 20/5% powdered milk and

Conversion of Signals from Ion-specific Electrodes to Linear Concentrations 1

PubMed Central

Heath, Robert L.

1975-01-01

This paper describes the assembly (from commercially available components) of an antilog converter, which transforms the output signals of ion-specific electrodes to ionic concentrations suitable for a linear recorder. It responds linearly to cation concentrations from 10 μm to at least 10 mm and can be used for electrodes kept at any temperatures (0 to 50 C). The leakage of K+ from a unicellular algae (Chlorella sorokiniana) can be induced by Triton X-100, heating, or suspension in a tris buffer and is used to demonstrate the operation of this device. PMID:16659270

Enzymatic hydrolysis of organic phosphorus in swine manure and soil.

PubMed

He, Zhongqi; Griffin, Timothy S; Honeycutt, C Wayne

2004-01-01

Organic phosphorus (Po) exists in many chemical forms that differ in their susceptibility to hydrolysis and, therefore, bioavailability to plants and microorganisms. Identification and quantification of these forms may significantly contribute to effective agricultural P management. Phosphatases catalyze reactions that release orthophosphate (Pi) from Po compounds. Alkaline phosphatase in tris-HCl buffer (pH 9.0), wheat (Triticum aestivum L.) phytase in potassium acetate buffer (pH 5.0), and nuclease P1 in potassium acetate buffer (pH 5.0) can be used to classify and quantify Po in animal manure. Background error associated with different pH and buffer systems is observed. In this study, we improved the enzymatic hydrolysis approach and tested its applicability for investigating Po in soils, recognizing that soil and manure differ in numerous physicochemical properties. We applied (i) acid phosphatase from potato (Solanum tuberosum L.), (ii) acid phosphatases from both potato and wheat germ, and (iii) both enzymes plus nuclease P1 to identify and quantify simple labile monoester P, phytate (myo-inositol hexakis phosphate)-like P, and DNA-like P, respectively, in a single pH/buffer system (100 mM sodium acetate, pH 5.0). This hydrolysis procedure released Po in sequentially extracted H2O, NaHCO3, and NaOH fractions of swine (Sus scrofa) manure, and of three sandy loam soils. Further refinement of the approach may provide a universal tool for evaluating hydrolyzable Po from a wide range of sources.

Studies on the interaction of apigenin with calf thymus DNA by spectroscopic methods

NASA Astrophysics Data System (ADS)

Zhang, Shufang; Sun, Xuejun; Kong, Rongmei; Xu, Mingming

2015-02-01

The interaction between apigenin and calf thymus deoxyribonucleic acid (ctDNA) in a pH 7.4 Tris-HCl buffer solution was investigated by UV-Vis spectroscopy, fluorescence spectroscopy, DNA melting techniques, and viscosity measurements. It was found that apigenin molecules could intercalate into the base pairs of DNA, forming a apigenin-DNA complex with a binding constant of K310K = 6.4 × 104 L mol-1. The thermodynamic parameters enthalpy change (ΔH), entropy change (ΔS) and Gibbs free energy (ΔG) were calculated to be 7.36 × 104 J mol-1, 329 J K-1 mol-1 and -2.84 × 104 J mol-1 at 310 K, respectively. Hydrophobic interaction was the predominant intermolecular force in stabilizing the apigenin-DNA complex. Thermal denaturation study suggested that the stabilization of the ctDNA helix was increased when the apigenin binding to ctDNA as indicated by the increase in thermal denaturation temperature of ctDNA at around 5.0 °C in the presence of apigenin. Spectroscopic techniques together with melting techniques and viscosity determination provided evidences of intercalation mode of binding for the interaction between apigenin and ctDNA.

Highly sensitive and stable electrochemical sulfite biosensor incorporating a bacterial sulfite dehydrogenase.

PubMed

Kalimuthu, Palraj; Tkac, Jan; Kappler, Ulrike; Davis, Jason J; Bernhardt, Paul V

2010-09-01

This paper describes a highly sensitive electrochemical (voltammetric) determination of sulfite using a combination of Starkeya novella sulfite dehydrogenase (SDH), horse heart cytochrome c (cyt c), and a self-assembled monolayer of 11-mercaptoundecanol (MU) cast on a gold electrode. The biosensor was optimized in terms of pH and the ratio of cyt c/SDH. The electrocatalytic oxidation current of sulfite increased linearly from 1 to 6 microM at the enzyme-modified electrode with a correlation coefficient of 0.9995 and an apparent Michaelis constant (K(M,app)) of 43 microM. Using an amperometric method, the low detection limit for sulfite at the enzyme-modified electrode was 44 pM (signal-to-noise ratio = 3). The modified electrode retained a stable response for 3 days while losing only ca. 4% of its initial sensitivity during a 2 week storage period in 50 mM Tris buffer solution at 4 degrees C. The enzyme electrode was successfully used for the determination of sulfite in beer and white wine samples. The results of these electrochemical analyses agreed well with an independent spectrophotometric method using Ellman's reagent, but the detection limit was far superior using the electrochemical method.

Gossip-based solutions for discrete rendezvous in populations of communicating agents.

PubMed

Hollander, Christopher D; Wu, Annie S

2014-01-01

The objective of the rendezvous problem is to construct a method that enables a population of agents to agree on a spatial (and possibly temporal) meeting location. We introduce the buffered gossip algorithm as a general solution to the rendezvous problem in a discrete domain with direct communication between decentralized agents. We compare the performance of the buffered gossip algorithm against the well known uniform gossip algorithm. We believe that a buffered solution is preferable to an unbuffered solution, such as the uniform gossip algorithm, because the use of a buffer allows an agent to use multiple information sources when determining its desired rendezvous point, and that access to multiple information sources may improve agent decision making by reinforcing or contradicting an initial choice. To show that the buffered gossip algorithm is an actual solution for the rendezvous problem, we construct a theoretical proof of convergence and derive the conditions under which the buffered gossip algorithm is guaranteed to produce a consensus on rendezvous location. We use these results to verify that the uniform gossip algorithm also solves the rendezvous problem. We then use a multi-agent simulation to conduct a series of simulation experiments to compare the performance between the buffered and uniform gossip algorithms. Our results suggest that the buffered gossip algorithm can solve the rendezvous problem faster than the uniform gossip algorithm; however, the relative performance between these two solutions depends on the specific constraints of the problem and the parameters of the buffered gossip algorithm.

Gossip-Based Solutions for Discrete Rendezvous in Populations of Communicating Agents

PubMed Central

Hollander, Christopher D.; Wu, Annie S.

2014-01-01

The objective of the rendezvous problem is to construct a method that enables a population of agents to agree on a spatial (and possibly temporal) meeting location. We introduce the buffered gossip algorithm as a general solution to the rendezvous problem in a discrete domain with direct communication between decentralized agents. We compare the performance of the buffered gossip algorithm against the well known uniform gossip algorithm. We believe that a buffered solution is preferable to an unbuffered solution, such as the uniform gossip algorithm, because the use of a buffer allows an agent to use multiple information sources when determining its desired rendezvous point, and that access to multiple information sources may improve agent decision making by reinforcing or contradicting an initial choice. To show that the buffered gossip algorithm is an actual solution for the rendezvous problem, we construct a theoretical proof of convergence and derive the conditions under which the buffered gossip algorithm is guaranteed to produce a consensus on rendezvous location. We use these results to verify that the uniform gossip algorithm also solves the rendezvous problem. We then use a multi-agent simulation to conduct a series of simulation experiments to compare the performance between the buffered and uniform gossip algorithms. Our results suggest that the buffered gossip algorithm can solve the rendezvous problem faster than the uniform gossip algorithm; however, the relative performance between these two solutions depends on the specific constraints of the problem and the parameters of the buffered gossip algorithm. PMID:25397882

Calorimetric and Diffractometric Evidence for the Sequential Crystallization of Buffer Components and the Consequential pH Swing in Frozen Solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sundaramurthi, Prakash; Shalaev, Evgenyi; Suryanarayanan, Raj

2010-06-22

Sequential crystallization of succinate buffer components in the frozen solution has been studied by differential scanning calorimetry and X-ray diffractometry (both laboratory and synchrotron sources). The consequential pH shifts were monitored using a low-temperature electrode. When a solution buffered to pH < pK{sub a2} was cooled from room temperature (RT), the freeze-concentrate pH first increased and then decreased. This was attributed to the sequential crystallization of succinic acid, monosodium succinate, and finally disodium succinate. When buffered to pH > pK{sub a2}, the freeze-concentrate pH first decreased and then increased due to the sequential crystallization of the basic (disodium succinate) followedmore » by the acidic (monosodium succinate and succinic acid) buffer components. XRD provided direct evidence of the crystallization events in the frozen buffer solutions, including the formation of disodium succinate hexahydrate [Na{sub 2}(CH{sub 2}COO){sub 2} {center_dot} 6H{sub 2}O]. When the frozen solution was warmed in a differential scanning calorimeter, multiple endotherms attributable to the melting of buffer components and ice were observed. When the frozen solutions were dried under reduced pressure, ice sublimation was followed by dehydration of the crystalline hexahydrate to a poorly crystalline anhydrate. However, crystalline succinic acid and monosodium succinate were retained in the final lyophiles. The pH and the buffer salt concentration of the prelyo solution influenced the crystalline salt content in the final lyophile. The direction and magnitude of the pH shift in the frozen solution depended on both the initial pH and the buffer concentration. In light of the pH-sensitive nature of a significant fraction of pharmaceuticals (especially proteins), extreme care is needed in both the buffer selection and its concentration.« less

Electrochromic Salts, Solutions, and Devices

DOEpatents

Burrell, Anthony K.; Warner, Benjamin P.; McClesky, T. Mark

2008-11-11

Electrochromic salts. Electrochromic salts of dicationic viologens such as methyl viologen and benzyl viologen associated with anions selected from bis(trifluoromethylsulfonyl)imide, bis(perfluoroethylsulfonyl)imide, and tris(trifluoromethylsulfonyl)methide are produced by metathesis with the corresponding viologen dihalide. They are highly soluble in molten quarternary ammonium salts and together with a suitable reductant provide electrolyte solutions that are used in electrochromic windows.

Electrochromic salts, solutions, and devices

DOEpatents

Burrell, Anthony K [Los Alamos, NM; Warner, Benjamin P [Los Alamos, NM; McClesky,7,064,212 T. Mark

2006-06-20

Electrochromic salts. Electrochromic salts of dicationic viologens such as methyl viologen and benzyl viologen associated with anions selected from bis(trifluoromethylsulfonyl)imide, bis(perfluoroethylsulfonyl)imide, and tris(trifluoromethylsulfonyl)methide are produced by metathesis with the corresponding viologen dihalide. They are highly soluble in molten quarternary ammonium salts and together with a suitable reductant provide electrolyte solutions that are used in electrochromic windows.

Electrochromic Salts, Solutions, and Devices

DOEpatents

Burrell, Anthony K.; Warner, Benjamin P.; McClesky, T. Mark

2008-10-14

Electrochromic salts. Electrochromic salts of dicationic viologens such as methyl viologen and benzyl viologen associated with anions selected from bis(trifluoromethylsulfonyl)imide, bis(perfluoroethylsulfonyl)imide, and tris(trifluoromethylsulfonyl)methide are produced by metathesis with the corresponding viologen dihalide. They are highly soluble in molten quarternary ammonium salts and together with a suitable reductant provide electrolyte solutions that are used in electrochromic windows.

Inhibition of Protein Carbamylation in Urea Solution Using Ammonium Containing Buffers

PubMed Central

Sun, Shisheng; Zhou, Jian-Ying; Yang, Weiming; Zhang, Hui

2013-01-01

Urea solution is one of the most commonly employed protein denaturants for protease digestion in proteomic studies. However, it has long been recognized that urea solution can cause carbamylation at the N-termini of proteins/peptides and at the side chain amino groups of lysine and arginine residues. Protein/peptide carbamylation blocks protease digestion and affects protein identification and quantification in mass spectrometry analysis by blocking peptide amino groups from isotopic/isobaric labeling and changing peptide charge states, retention times and masses. In addition, protein carbamylation during sample preparation makes it difficult to study in vivo protein carbamylation. In this study, we compared the peptide carbamylation in urea solutions of different buffers and found that ammonium containing buffers were the most effective buffers to inhibit protein carbamylation in urea solution. The possible mechanism of carbamylation inhibition by ammonium containing buffers is discussed, and a revised procedure for the protease digestion of proteins in urea and ammonium containing buffers was developed to facilitate its application in proteomic research. PMID:24161613

Buffers more than buffering agent: introducing a new class of stabilizers for the protein BSA.

PubMed

Gupta, Bhupender S; Taha, Mohamed; Lee, Ming-Jer

2015-01-14

In this study, we have analyzed the influence of four biological buffers on the thermal stability of bovine serum albumin (BSA) using dynamic light scattering (DLS). The investigated buffers include 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid (HEPES), 4-(2-hydroxyethyl)-1-piperazine-propanesulfonic acid (EPPS), 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid sodium salt (HEPES-Na), and 4-morpholinepropanesulfonic acid sodium salt (MOPS-Na). These buffers behave as a potential stabilizer for the native structure of BSA against thermal denaturation. The stabilization tendency follows the order of MOPS-Na > HEPES-Na > HEPES ≫ EPPS. To obtain an insight into the role of hydration layers and peptide backbone in the stabilization of BSA by these buffers, we have also explored the phase transition of a thermoresponsive polymer, poly(N-isopropylacrylamide (PNIPAM)), a model compound for protein, in aqueous solutions of HEPES, EPPS, HEPES-Na, and MOPS-Na buffers at different concentrations. It was found that the lower critical solution temperatures (LCST) of PNIPAM in the aqueous buffer solutions substantially decrease with increase in buffer concentration. The mechanism of interactions between these buffers and protein BSA was probed by various techniques, including UV-visible, fluorescence, and FTIR. The results of this series of studies reveal that the interactions are mainly governed by the influence of the buffers on the hydration layers surrounding the protein. We have also explored the possible binding sites of BSA with these buffers using a molecular docking technique. Moreover, the activities of an industrially important enzyme α-chymotrypsin (α-CT) in 0.05 M, 0.5 M, and 1.0 M of HEPES, EPPS, HEPES-Na, and MOPS-Na buffer solutions were analyzed at pH = 8.0 and T = 25 °C. Interestingly, the activities of α-CT were found to be enhanced in the aqueous solutions of these investigated buffers. Based upon the Jones-Dole viscosity parameters, the kosmotropic or chaotropic behaviors of the investigated buffers at 25 °C have been examined.

Reaction of fluorogenic reagents with proteins

PubMed Central

Swearingen, Kristian E.; Dickerson, Jane A.; Turner, Emily H.; Ramsay, Lauren M.; Wojcik, Roza; Dovichi, Norman J.

2009-01-01

The fluorogenic reagent Chromeo P465 is considered for analysis of proteins by capillary electrophoresis with laser-induced fluorescence detection. The reagent was first used to label α-lactalbumin; the product was analyzed by capillary zone electrophoresis in a sub-micellar sodium dodecyl sulfate (SDS) buffer. The product generated a set of equally spaced but poorly resolved peaks that formed a broad envelope with a net mobility of 4 × 10−4 cm2 V−1 s−1. The components of the envelope were presumably protein that had reacted with different numbers of labels. The mobility of these components decreased by roughly 1 % with the addition of each label. The signal increased linearly from 1.0 nM to 100 nM α-lactalbumin (r2 = 0.99), with a 3σ detection limit of 70 pM. We then considered the separation of a mixture of ovalbumin, α-chymotrypsinogen A, and αlactalbumin labeled with Chromeo P465; unfortunately, baseline resolution was not achieved with a borax/SDS buffer. Better resolution was achieved with N-cyclohexyl-2-aminoethanesulfonic acid/Tris/SDS/dextran capillary sieving electrophoresis; however, dye interactions with this buffer system produced a less than ideal blank. PMID:18479693

Conditions affecting transformation of a group H streptococcus.

PubMed

Schlissel, H J; Sword, C P

1966-11-01

Schlissel, Harvey J. (The University of Kansas, Lawrence), and C. P. Sword. Conditions affecting transformation of a group H streptococcus. J. Bacteriol. 92:1357-1363. 1966.-A defined transforming medium (DTM) containing buffer and 5 to 10 mug per ml of deoxyribonucleic acid was developed to study the physical and chemical requirements for optimal transformation in streptococcal strain SBE. Optimal transformation in DTM occurred at pH 7.5 and 7.0 in 0.07 m sodium phosphate buffer and 0.05 m tris(hydroxymethyl)aminomethane buffer, respectively. In the presence of either a monovalent or a divalent cation, transformation was stimulated maximally by Mn(+2) (10(-3)m) and K(+) (0.05 m). Other cations tested (Na(+), Mg(+2), Ca(+2)) were less stimulatory. A mixture of K(+) and Mn(+2) stimulated transformation to a level higher than either cation alone. Kinetic studies showed that the stimulating effect of cations was greatest during the early part of the transformation reaction and decreased with time. Transformation was inhibited by Cu(+2) (10(-5)m) and Mn(+2) (10(-2)m). Ethylenediaminetetraacetic acid (EDTA) inhibited transformation at 10(-5)m. The inhibition by EDTA could be overcome by Mn(+2) during the early part of the transformation reaction.

Efficient extraction of vaccines formulated in aluminum hydroxide gel by including surfactants in the extraction buffer

PubMed Central

Zhu, Daming; Huang, Shuhui; McClellan, Holly; Dai, Weili; Syed, Najam R; Gebregeorgis, Elizabeth; Mullen, Gregory E. D.; Long, Carole; Martin, Laura B.; Narum, David; Duffy, Patrick; Miller, Louis H.; Saul, Allan

2011-01-01

Efficient antigen extraction from vaccines formulated on aluminum hydroxide gels is a critical step for the evaluation of the quality of vaccines following formulation. It has been shown in our laboratory that the efficiency of antigen extraction from vaccines formulated on Alhydrogel decreased significantly with increased storage time. To increase antigen extraction efficiency, the present study determined the effect of surfactants on antigen recovery from vaccine formulations. The Plasmodium falciparum apical membrane antigen 1 (AMA1) formulated on Alhydrogel and stored at 2-8 °C for three years was used as a model in this study. The AMA1 on Alhydrogel was extracted in the presence or absence of 30 mM sodium dodecyl sulfate (SDS) or 20 mM cetylpyridinium chloride in the extraction buffer (0.60 M citrate, 0.55 M phosphate, pH 8.5) using our standard antigen extraction protocols. Extracted AMA1 antigen was analyzed by 4-20% Tris-glycine SDS-PAGE followed by silver staining or western blotting. The results showed that inclusion of SDS or cetylpyridinium chloride in extraction buffer increased the antigen recovery dramatically and can be used for efficient characterization of Alhydrogel vaccines. PMID:22107848

Predicting the crystallization propensity of carboxylic acid buffers in frozen systems--relevance to freeze-drying.

PubMed

Sundaramurthi, Prakash; Suryanarayanan, Raj

2011-04-01

Selective crystallization of buffer components in frozen solutions is known to cause pronounced pH shifts. Our objective was to study the crystallization behavior and the consequent pH shift in frozen aqueous carboxylic acid buffers. Aqueous carboxylic acid buffers were cooled to -25°C and the pH of the solution was measured as a function of temperature. The thermal behavior of solutions during freezing and thawing was investigated by differential scanning calorimetry. The crystallized phases in frozen solution were identified by X-ray diffractometry. The malate buffer system was robust with no evidence of buffer component crystallization and hence negligible pH shift. In the citrate and tartarate systems, at initial pH

Electrodialysis operation with buffer solution

DOEpatents

Hryn, John N [Naperville, IL; Daniels, Edward J [Orland Park, IL; Krumdick, Greg K [Crete, IL

2009-12-15

A new method for improving the efficiency of electrodialysis (ED) cells and stacks, in particular those used in chemical synthesis. The process entails adding a buffer solution to the stack for subsequent depletion in the stack during electrolysis. The buffer solution is regenerated continuously after depletion. This buffer process serves to control the hydrogen ion or hydroxide ion concentration so as to protect the active sites of electrodialysis membranes. The process enables electrodialysis processing options for products that are sensitive to pH changes.

New tris(dopamine) derivative as an iron chelator. Synthesis, solution thermodynamic stability, and antioxidant research.

PubMed

Zhang, Qingchun; Jin, Bo; Shi, Zhaotao; Wang, Xiaofang; Lei, Shan; Tang, Xingyan; Liang, Hua; Liu, Qiangqiang; Gong, Mei; Peng, Rufang

2017-06-01

A new tris(dopamine) derivative, containing three dopamine chelate moieties which were attached to a trimesic acid molecular scaffold, has been prepared and fully characterized by NMR, FTIR and HRMS. The solution thermodynamic stability of the chelator with Fe(III), Mg(II), Zn(II) and Fe(II) ions was investigated. Results demonstrated that the chelator exhibited effective binding ability and improved selectivity to Fe(III) ion. The chelator possessed affinity similar to that of diethylenetriaminepentaacetic acid chelator for Fe(III) ion. The high affinity could be attributed to the favorable geometric arrangement between the chelator and Fe(III) ion coordination preference. The chelator also exhibited high antioxidant activity and nontoxicity to neuron-like rat pheochromocytoma cells. Hence, the chelator could be used as chelating agent for iron overload situations without depleting essential metal ions, such as Mg(II) and Zn(II) ions. Copyright © 2017. Published by Elsevier Inc.

N,N',N"-tris(dihydroxyphosphorylmethyl)-1,4,7-triazacyclononane (Deofix) - a high-affinity, high-specificity chelator for first transition series metal cations with significant deodorant, antimicrobial, and antioxidant activity.

PubMed

Laden, Karl; Zaklad, Haim; Simhon, Elliot D; Klein, Joseph Y; Cyjon, Rosa L; Winchell, Harry S

2003-01-01

Deofix, N,N',N"-tris(dihydroxyphosphorylmethyl)-1,4,7-triazacyclononane, is a high-affinity, high-specificity chelator for first transition series cations such as iron, zinc, manganese, and copper. A 1% solution in 50% ethanol was found to be significantly better at reducing underarm malodor than a solution of 0.3% Triclosan in 50% ethanol. Compared to a 50% alcohol control, Deofix was found to produce a significant reduction in malodor for at least 48 hours. Deofix appears to work by reducing the concentration of first transition series metal ions below the levels needed for microbial cell reproduction and by inhibiting oxidative processes by interfering with catalytic formation of free radicals. Deofix has very low levels of toxicity when measured via a number of screening techniques.

Assessment and kinetics of soil phosphatase in Brazilian Savanna systems.

PubMed

Ferreira, Adão S; Espíndola, Suéllen P; Campos, Maria Rita C

2016-05-31

The activity and kinetics of soil phosphatases are important indicators to evaluate soil quality in specific sites such as the Cerrado (Brazilian Savanna). This study aimed to determine the activity and kinetic parameters of soil phosphatase in Cerrado systems. Soil phosphatase activity was assessed in samples of native Cerrado (NC), no-tillage (NT), conventional tillage (CT) and pasture with Brachiaria brizantha (PBb) and evaluated with acetate buffer (AB), tris-HCl buffer (TB), modified universal buffer (MUB) and low MUB. The Michaelis-Menten equation and Eadie-Hofstee model were applied to obtain the kinetic parameters of soil phosphatase using different concentrations of p-nitrophenol phosphate (p-NPP). MUB showed the lowest soil phosphatase activity in all soils whereas AB in NC and NT presented the highest. Low MUB decreased interferences in the assessment of soil phosphatase activity when compared to MUB, suggesting that organic acids interfere on the soil phosphatase activity. In NC and NT, soil phosphatase activity performed with TB was similar to AB and low MUB. Km values from the Michaels-Menten equation were higher in NC than in NT, which indicate a lower affinity of phosphatase activity for the substrate in NC. Vmax values were also higher in NC than in NT. The Eadie-Hofstee model suggests that NC had more phosphatase isoforms than NT. The study showed that buffer type is of fundamental importance when assessing soil phosphatase activity in Cerrado soils.

Solid-state mAbs and ADCs subjected to heat-stress stability conditions can be covalently modified with buffer and excipient molecules.

PubMed

Valliere-Douglass, John F; Lewis, Patsy; Salas-Solano, Oscar; Jiang, Shan

2015-02-01

We report that a unique type of chemical modification occurs on lyophilized proteins. Freeze-dried mAbs and antibody-drug conjugates (ADCs) can be covalently modified with buffer and excipient molecules on the side chains of Glu, Asp, Thr, and Ser amino acids when subjected to temperature stress. The reaction occurs primarily via condensation of common buffers and excipients such as histidine, tris, trehalose and sucrose, with Glu and Asp carboxylates in the primary sequence of proteins. The reaction was also found to proceed through condensation of carboxylate containing buffers such as citrate, with Thr and Ser hydroxyls in the primary sequence of proteins. Based on the mass of the covalent adducts observed on mAbs and ADCs, it is apparent that the reaction produces water as a product and is thus favored in a low moisture environments such as a lyophilized protein cake. Herein, we present the evidence for the covalent modification of proteins drawn from case studies of in-depth characterization of heat-stressed mAbs and ADCs in the solid state. We also demonstrate how common charge variant assays such as imaged capillary isoelectric focusing and mass spectrometry can be used to monitor this specific class of protein modification. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

A pilot study of the efficacy of wipes containing chlorhexidine 0.3%, climbazole 0.5% and Tris-EDTA to reduce Malassezia pachydermatis populations on canine skin.

PubMed

Cavana, Paola; Peano, Andrea; Petit, Jean-Yanique; Tizzani, Paolo; Perrot, Sébastien; Bensignor, Emmanuel; Guillot, Jacques

2015-08-01

Wipes containing chlorhexidine and azole derivates have been recommended for veterinary use. No study has been published about their activity against Malassezia pachydermatis. To evaluate the in vivo and in vitro activity of wipes soaked in a chlorhexidine, climbazole and Tris-EDTA solution against Malassezia pachydermatis. Five research colony shar-pei dogs. Wipes were applied once daily onto the left axilla, left groin and perianal area (protocol A), and twice daily on the right axilla, right groin and umbilical region (protocol B) for 3 days. In vivo activity was evaluated by quantifying Malassezia colonies through contact plates on the selected body areas before and after wipe application. The activity of the solution in which the wipes were soaked was assessed in vitro by contact tests following the European Standard UNI EN 1275 guidelines. Samples collected after wipe application showed a significant and rapid reduction of Malassezia yeast CFU. No significant difference in the Malassezia reduction was found between protocols A and B. In vitro assay showed 100% activity against Malassezia yeasts after a 15 min contact time with the wipe solution. Wipes containing chlorhexidine, climbazole and Tris-EDTA substantially reduced the M. pachydermatis population on the skin of dogs. The results, although this was an uncontrolled study performed on a small number of dogs, suggest that these wipes may be useful for topical therapy of Malassezia dermatitis involving the lips, paws, perianal area and skin folds. © 2015 ESVD and ACVD.

Thermophysical properties of carboxylic and amino acid buffers at subzero temperatures: relevance to frozen state stabilization.

PubMed

Sundaramurthi, Prakash; Suryanarayanan, Raj

2011-06-02

Macromolecules and other thermolabile biologicals are often buffered and stored in frozen or dried (freeze-dried) state. Crystallization of buffer components in frozen aqueous solutions and the consequent pH shifts were studied in carboxylic (succinic, malic, citric, tartaric acid) and amino acid (glycine, histidine) buffers. Aqueous buffer solutions were cooled from room temperature (RT) to -25 °C and the pH of the solution was measured as a function of temperature. The thermal behavior of frozen solutions was investigated by differential scanning calorimetry (DSC), and the crystallized phases were identified by X-ray diffractometry (XRD). Based on the solubility of the neutral species of each buffer system over a range of temperatures, it was possible to estimate its degree of supersaturation at the subambient temperature of interest. This enabled us to predict its crystallization propensity in frozen systems. The experimental and the predicted rank orderings were in excellent agreement. The malate buffer system was robust with no evidence of buffer component crystallization and hence negligible pH shift. In the citrate and tartrate systems, at initial pH < pK(a)(2), only the most acidic buffer component (neutral form) crystallized on cooling, causing an increase in the freeze-concentrate pH. In glycine buffer solutions, when the initial pH was ∼3 units < isoelectric pH (pI = 5.9), β-glycine crystallization caused a small decrease in pH, while a similar effect but in the opposite direction was observed when the initial pH was ∼3 units > pI. In the histidine buffer system, depending on the initial pH, either histidine or histidine HCl crystallized.

Inhibition of protein carbamylation in urea solution using ammonium-containing buffers.

PubMed

Sun, Shisheng; Zhou, Jian-Ying; Yang, Weiming; Zhang, Hui

2014-02-01

Urea solution is one of the most commonly employed protein denaturants for protease digestion in proteomic studies. However, it has long been recognized that urea solution can cause carbamylation at the N termini of proteins/peptides and at the side chain amino groups of lysine and arginine residues. Protein/peptide carbamylation blocks protease digestion and affects protein identification and quantification in mass spectrometry analysis by blocking peptide amino groups from isotopic/isobaric labeling and changing peptide charge states, retention times, and masses. In addition, protein carbamylation during sample preparation makes it difficult to study in vivo protein carbamylation. In this study, we compared the peptide carbamylation in urea solutions of different buffers and found that ammonium-containing buffers were the most effective buffers to inhibit protein carbamylation in urea solution. The possible mechanism of carbamylation inhibition by ammonium-containing buffers is discussed, and a revised procedure for the protease digestion of proteins in urea and ammonium-containing buffers was developed to facilitate its application in proteomic research. Copyright © 2013 Elsevier Inc. All rights reserved.

Content and persistence of extracellular DNA in native soils

NASA Astrophysics Data System (ADS)

Blagodatskaya, Evgenia; Blagodatsky, Sergey; Anderson, Traute-Heidi; Kuzyakov, Yakov

2014-05-01

The long-term persistence of soil extracellular DNA is questionable because of high potential activity of nucleases produced by soil microorganisms. By the other hand, the relative persistence of DNA-like biopolymers could be due to their adsorption on clay minerals and humus substances in soil. High-specific and ultra sensitive reagent PicoGreenTM (Molecular Probes) permits the quantitative assessment of microbial dsDNA in diluted soil extracts giving a good tool for tracing the DNA fate in soil. Our goal was to determine intracellular and extracellular DNA content in cambisol (loamy sand) and in chernozem (silty loam) soils and to investigate the possible adsorption and degradation of extracellular DNA in soil. Optimized procedure of mechanical and enzymatic destruction of cell walls was used for direct extraction of microbial DNA with Tris-EDTA buffer (Blagodatskaya et al., 2003). Extracellular dsDNA was determined in distilled water and in Tris-EDTA extracts without enzymatic or mechanical treatments. DNA content was determined after addition of PicoGreen to diluted soil extracts. Degradation of extracellular DNA was traced during 24 h incubation of 2 µg lambda-phage DNA in soil. Possible DNA adsorption to soil matrix was determined by recovery of lambda -phage DNA added to autoclaved soil. Extracellular dsDNA was absent in water extracts of both soils. The content of extracellular dsDNA extracted by Tris-EDTA buffer was 0.46 µg/g in chernozem and 1.59 µg/g in cambisol amounting 0.43 and 2.8% of total dsDNA content in these soils, respectively. 100% and 64.8% of added extracellular lambda -phage dsDNA was found in cambisol and chernozem soils, respectively, in 5 h after application. 39% and 73.5% of added DNA disappeared in cambisol and in chernozem, respectively, during 24 h incubation. Degradation rate of extracellular DNA depended on microbial biomass content, which was 2.5 times higher in chernozem as compared to cambisol. Maximum adsorption of DNA by soils was observed in cambisol and reached 2.7% of added amount. We speculate that probability of gene transfer could be rather high in soils, taking into account possible increase of extracellular DNA content after transient environmental events (i.e. drying - rewetting and freezing - thawing).

Novel 3-hydroxypropyl bonded phase by direct hydrosilylation of allyl alcohol on amorphous hydride silica

PubMed Central

Gómez, Jorge E.; Navarro, Fabián H.; Sandoval, Junior E.

2015-01-01

A novel 3-hydroxypropyl (propanol) bonded silica phase has been prepared by hydrosilylation of allyl alcohol on a hydride silica intermediate, in the presence of platinum (0)-divinyltetramethyldisiloxane (Karstedt's catalyst). The regio-selectivity of this synthetic approach had been correctly predicted by previous reports involving octakis(dimethylsiloxy)octasilsesquioxane (Q8M8H) and hydrogen silsesquioxane (T8H8), as molecular analogs of hydride amorphous silica. Thus, C-silylation predominated (~ 94%) over O-silylation, and high surface coverages of propanol groups (5±1 µmol/m2) were typically obtained in this work. The propanol-bonded phase was characterized by spectroscopic (IR and solid state NMR on silica microparticles), contact angle (on fused-silica wafers) and CE (on fused-silica tubes) techniques. CE studies of the migration behavior of pyridine, caffeine, tris(2,2’-bipyridine)Ru(II) chloride and lysozyme on propanol-modified capillaries were carried out. The adsorption properties of these select silanol-sensitive solutes were compared to those on the unmodified and hydride-modified tubes. It was found that hydrolysis of the SiH species underlying the immobilized propanol moieties leads mainly to strong ion-exchange based interactions with the basic solutes at pH 4, particularly with lysozyme. Interestingly, and in agreement with water contact angle and electroosmotic mobility figures, the silanol-probe interactions on the buffer-exposed (hydrolyzed) hydride surface are quite different from those of the original unmodified tube. PMID:24934906

Purification of Restriction Endonuclease EcoRII and its Co-Crystallization

NASA Technical Reports Server (NTRS)

Karpova, E. A.; Chen, L.; Meehan, E.; Pusey, M.; Rose, M. Franklin (Technical Monitor)

2000-01-01

Restriction endonuclease EcoRII (EcoRII) is a homodimeric DNA-binding protein. It belongs to the type II family of restriction-modification enzymes (subclass IIe). EcoRII recognizes the nucleotide sequence 5'-CCWGG (W=A or T) and cleaves the phosphodiester bond preceding the first cytosine. Methylation at C5 of the second cytosine inhibits cleavage. The enzyme has a unique ability to search for the presence of two substrate sites before cleavage. To the best of our knowledge no other subclass IIe restriction endonuclease has been crystallized yet, without or with a DNA-substrate. We have recently grown and characterized the crystals of this enzyme (1) Here we report on the result of co-crystallization experiments of EcoRII with an 11 b.p. oligonucleotide substrate. The dissociation constant (Kd) EcoRII: 11 b.p. was determined earlier (unpublished results). The needle-like crystals of oligonucleotide-EcoRII protein complex were obtained with this substrate by the technique of vapor diffusion hanging drops. The crystals obtained were washed and dissolved in an aliquot of 10 mM Tris-HCl buffer, pH=7.5. Running a portion of this solution on the SDS-get indicated the presence of endonuclease in the solution. A UV-spectrophotometric test of a second portion confirmed the presence of DNA. We are now working on improvement of the DNA-EcoRII protein crystals. Results obtained from these and ongoing efforts will be reported.

Interactions of proteins in human plasma with modified polystyrene resins.

PubMed

Boisson-Vidal, C; Jozefonvicz, J; Brash, J L

1991-01-01

Investigations are reported on the composition of protein layers adsorbed from plasma to various modified polystyrene resins. As well as polystyrene itself, polystyrene bearing sulfonate groups in the benzene rings, and polystyrene sulfonate in which the sulfonate groups were converted to amino acid sulfamide, were investigated. Some of these resins were shown in previous work to have anticoagulant properties. To study the adsorption of proteins from plasma, the resins were exposed to citrate anticoagulated human plasma for 3 h. Adsorbed proteins were then eluted sequentially by 1M Tris buffer and 4% SDS solution, and examined by SDS-PAGE. The gel patterns were similar on all resins except polystyrene. From the MWs of the gel bands, the major protein component appeared to be fibrinogen. Smaller amounts of plasminogen, transferrin, albumin, and IgG were also present. In addition, Ouchterlony immunoassay of the eluates from one resin gave positive identification of complement C3, fibronectin, IgG, and IgM. Many other minor gel bands remain unidentified. A consistent finding for all resins was the presence of plasmin-type fibrinogen degradation products though the amounts varied with resin type. It is concluded from this (and from experiments showing FDP formation when fibrinogen was absorbed to the resins, from buffer containing a trace of plasminogen) that the functional groups in these materials promote the adsorption of plasminogen and its activation to a plasmin-like molecule. It appears from the substantial quantities of fibrinogen adsorbed to these materials after 3 h exposure to plasma that the Vroman effect (giving transient adsorption of fibrinogen) is not operative on these materials. It is hypothesized that specific interactions occur between fibrinogen and sulfonate groups.

Optimalization of Poly(neutral red) Coated-wire Electrode for Determination of Citrate in Soft Drinks

PubMed Central

Broncová, Gabriela; Shishkanova, Tatiana V.; Krondak, Martin; Volf, Radko; Král, Vladimír

2008-01-01

This report presents an optimization of potentiometric measurements with citrate-selective electropolymerized poly(neutral red) electrodes. The optimal background electrolyte for these measurements is a TRIS buffer with nitrate at pH 8.5. The electrodes described here exhibit stable and reproducible near-Nernstian response to citrates with a low detection limit of 6 × 10-6 M. Electrodes polymerized from sulfuric acid and acetonitrile are compared in detail. Simple and sensitive method for quantification of citrate in real-life samples by potentiometry with poly(neutral red) electrodes are presented. Data from potentiometric measurements of citrate are compared with capillary electrophoresis. PMID:27879724

Glucose buffer is suitable for blood group conversion with α-N acetylgalactosaminidase and α-galactosidase.

PubMed

Gao, Hong-Wei; Li, Su-Bo; Bao, Guo-Qiang; Zhang, Xue; Li, Hui; Wang, Ying-Li; Tan, Ying-Xia; Ji, Shou-Ping; Gong, Feng

2014-01-01

It is well known that the buffer plays a key role in the enzymatic reaction involved in blood group conversion. In previous study, we showed that a glycine buffer is suitable for A to O or B to O blood group conversion. In this study, we investigated the use of 5% glucose and other buffers for A to O or B to O blood group conversion by α-N-acetylgalactosaminidase or α-galactosidase. We compared the binding ability of α-N-acetylgalactosaminidase/α-galactosidase with red blood cells (RBC) in different reaction buffers, such as normal saline, phosphate-buffered saline (PBS), a disodium hydrogen phosphate-based buffer (PCS), and 5% commercial glucose solution. The doses of enzymes necessary for the A/B to O conversion in different reaction buffers were determined and compared. The enzymes' ability to bind to RBC was evaluated by western blotting, and routine blood typing and fluorescence activated cell sorting was used to evaluate B/A to O conversion efficiency. The A to O conversion efficiency in glucose buffer was similar to that in glycine buffer with the same dose (>0.06 mg/mL pRBC). B to O conversion efficiency in glucose buffer was also similar to that in glycine buffer with the same dose (>0.005 mg/mL pRBC). Most enzymes could bind with RBC in glycine or glucose buffer, but few enzymes could bind with RBC in PBS, PCS, or normal saline. These results indicate that 5% glucose solution provides a suitable condition for enzymolysis, especially for enzymes combining with RBC. Meanwhile, the conversion efficiency of A/B to O was similar in glucose buffer and glycine buffer. Moreover, 5% glucose solution has been used for years in venous transfusion, it is safe for humans and its cost is lower. Our results do, therefore, suggest that 5% glucose solution could become a novel suitable buffer for A/B to O blood group conversion.

Ultrasonication as a potential tool to predict solute crystallization in freeze-concentrates.

PubMed

Ragoonanan, Vishard; Suryanarayanan, Raj

2014-06-01

We hypothesize that ultrasonication can accelerate solute crystallization in freeze-concentrates. Our objective is to demonstrate ultrasonication as a potential predictive tool for evaluating physical stability of excipients in frozen solutions. The crystallization tendencies of lyoprotectants (trehalose, sucrose), carboxylic acid buffers (citric, tartaric, malic, and acetic) and an amino acid buffer (histidine HCl) were studied. Aqueous solutions of buffers, lyoprotectants and mixtures of the two were cooled from room temperature to -20°C and sonicated to induce solute crystallization. The crystallized phases were identified by X-ray diffractometry (laboratory or synchrotron source). Sonication accelerated crystallization of trehalose dihydrate in frozen trehalose solutions. Sonication also enhanced solute crystallization in tartaric (200 mM; pH 5), citric (200 mM pH 4) and malic (200 mM; pH 4) acid buffers. At lower buffer concentrations, longer annealing times following sonication were required to facilitate solute crystallization. The time for crystallization of histidine HCl progressively increased as a function of sucrose concentration. The insonation period required to effect crystallization also increased with sucrose concentration. Sonication can substantially accelerate solute crystallization in the freeze-concentrate. Ultrasonication may be useful in assessing the crystallization tendency of formulation constituents used in long term frozen storage and freeze-drying.

Osmotic agents and buffers in peritoneal dialysis solution: monocyte cytokine release and in vitro cytotoxicity.

PubMed

Plum, J; Schoenicke, G; Grabensee, B

1997-09-01

Peritonitis remains a major problem in peritoneal dialysis. The incidence of peritonitis may be reduced by the use of more "biocompatible" peritoneal dialysis solutions that do not impair local host defense mechanisms, such as occurs with conventional lactate-buffered glucose solutions. In the present study, we investigated the use of bicarbonate and lactate as buffer systems and glucose, amino acids, and glucose polymer as osmotic agents on specific cellular functions of isolated fresh blood monocytes in vitro. The bicarbonate-buffered solutions had a physiologic pH (7.0 to 7.6). Lactate-buffered solutions were tested with a pH between 5.5 and 7.3. RPMI 1640 (Roswell Park Memorial Institute, supplied by Biochrom, Berlin, Germany) and phosphate-buffered saline were used as control mediums. The test solutions were incubated with 200,000 monocytes/mL for 45 minutes followed by a 1:1 mix with RPMI 1640 (with supplements) during a 24- or 4-hour tetrazolium bromide test (MTT test) recovery period. Constitutive and lipopolysaccharide (LPS)-stimulated release of interleukin-1beta (IL-1beta) and IL-6 in the supernatants as parameters of cellular host defense and lactate dehydrogenase concentrations and MTT-formazan production as parameters for cell cytotoxicity were measured. Significantly higher IL-6 and IL-1beta release was found in the bicarbonate-buffered solutions, both under basal conditions and after LPS stimulation, compared with the lactate-buffered solutions (LPS stimulation: 1% amino acids/34 mmol/L bicarbonate, IL-1beta: 1,166 +/- 192 pg/mL; 1.5% glucose/34 mmol/L bicarbonate, IL-1beta: 752 +/- 107 pg/mL; 1.5% glucose/35 mmol/L lactate/pH 5.5, IL-1beta: 174 +/- 51 pg/mL). Some of these differences could even be detected in spent dialysate after a 6-hour dwell in continuous ambulatory peritoneal dialysis patients (n = 10). A lower degree of cellular cytotoxicity (lactate dehydrogenase activity) and better-preserved metabolic activity (MTT test) also were found for the bicarbonate-buffered solutions. Amino acids (1%) proved to be comparable to glucose (1.5%) as an osmotic agent at a neutral pH with regard to LPS-stimulated cytokine release and cytotoxicity. The incubation with a glucose polymer solution (7.5% glucose polymer in phosphate-buffered saline, pH 7.3) resulted in a significantly lowered cytokine release (LPS stimulation: IL-1beta, 69 +/- 19 pg/mL) compared with the other solutions with neutral pH (P < 0.01). These results suggest that bicarbonate as a buffer provided better biocompatibility with regard to mononuclear cytokine release and viability compared with lactate. Amino acids and glucose were equivalent to these parameters at a physiologic pH. The glucose polymer solution, however, was associated with a marked depression of cytokine release.

Hierarchical bioceramic scaffolds with 3D-plotted macropores and mussel-inspired surface nanolayers for stimulating osteogenesis

NASA Astrophysics Data System (ADS)

Xu, Mengchi; Zhai, Dong; Xia, Lunguo; Li, Hong; Chen, Shiyi; Fang, Bing; Chang, Jiang; Wu, Chengtie

2016-07-01

The hierarchical structure of biomaterials plays an important role in the process of tissue reconstruction and regeneration. 3D-plotted scaffolds have been widely used for bone tissue engineering due to their controlled macropore structure and mechanical properties. However, the lack of micro- or nano-structures on the strut surface of 3D-plotted scaffolds, especially for bioceramic scaffolds, limits their biological activity. Inspired by the adhesive versatility of mussels and the active ion-chelating capacity of polydopamine, we set out to prepare a hierarchical bioceramic scaffold with controlled macropores and mussel-inspired surface nanolayers by combining the 3D-plotting technique with the polydopamine/apatite hybrid strategy in order to synergistically accelerate the osteogenesis and angiogenesis. β-Tricalcium phosphate (TCP) scaffolds were firstly 3D-plotted and then treated in dopamine-Tris/HCl and dopamine-SBF solutions to obtain TCP-DOPA-Tris and TCP-DOPA-SBF scaffolds, respectively. It was found that polydopamine/apatite hybrid nanolayers were formed on the surface of both TCP-DOPA-Tris and TCP-DOPA-SBF scaffolds and TCP-DOPA-SBF scaffolds induced apatite mineralization for the second time during the cell culture. As compared to TCP scaffolds, both TCP-DOPA-Tris and TCP-DOPA-SBF scaffolds significantly promoted the osteogenesis of bone marrow stromal cells (BMSCs) as well as the angiogenesis of human umbilical vein endothelial cells (HUVECs), and the TCP-DOPA-SBF group presented the highest in vitro osteogenic/angiogenic activity among the three groups. Furthermore, both TCP-DOPA-Tris and TCP-DOPA-SBF scaffolds significantly improved the formation of new bone in vivo as compared to TCP scaffolds without a nanostructured surface. Our results suggest that the utilization of a mussel-inspired Ca, P-chelated polydopamine nanolayer on 3D-plotted bioceramic scaffolds is a viable and effective strategy to construct a hierarchical structure for synergistically accelerating osteogenesis.The hierarchical structure of biomaterials plays an important role in the process of tissue reconstruction and regeneration. 3D-plotted scaffolds have been widely used for bone tissue engineering due to their controlled macropore structure and mechanical properties. However, the lack of micro- or nano-structures on the strut surface of 3D-plotted scaffolds, especially for bioceramic scaffolds, limits their biological activity. Inspired by the adhesive versatility of mussels and the active ion-chelating capacity of polydopamine, we set out to prepare a hierarchical bioceramic scaffold with controlled macropores and mussel-inspired surface nanolayers by combining the 3D-plotting technique with the polydopamine/apatite hybrid strategy in order to synergistically accelerate the osteogenesis and angiogenesis. β-Tricalcium phosphate (TCP) scaffolds were firstly 3D-plotted and then treated in dopamine-Tris/HCl and dopamine-SBF solutions to obtain TCP-DOPA-Tris and TCP-DOPA-SBF scaffolds, respectively. It was found that polydopamine/apatite hybrid nanolayers were formed on the surface of both TCP-DOPA-Tris and TCP-DOPA-SBF scaffolds and TCP-DOPA-SBF scaffolds induced apatite mineralization for the second time during the cell culture. As compared to TCP scaffolds, both TCP-DOPA-Tris and TCP-DOPA-SBF scaffolds significantly promoted the osteogenesis of bone marrow stromal cells (BMSCs) as well as the angiogenesis of human umbilical vein endothelial cells (HUVECs), and the TCP-DOPA-SBF group presented the highest in vitro osteogenic/angiogenic activity among the three groups. Furthermore, both TCP-DOPA-Tris and TCP-DOPA-SBF scaffolds significantly improved the formation of new bone in vivo as compared to TCP scaffolds without a nanostructured surface. Our results suggest that the utilization of a mussel-inspired Ca, P-chelated polydopamine nanolayer on 3D-plotted bioceramic scaffolds is a viable and effective strategy to construct a hierarchical structure for synergistically accelerating osteogenesis. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01952h

Electrolytic method to make alkali alcoholates using ion conducting alkali electrolyte/separator

DOEpatents

Joshi, Ashok V [Salt Lake City, UT; Balagopal, Shekar [Sandy, UT; Pendelton, Justin [Salt Lake City, UT

2011-12-13

Alkali alcoholates, also called alkali alkoxides, are produced from alkali metal salt solutions and alcohol using a three-compartment electrolytic cell. The electrolytic cell includes an anolyte compartment configured with an anode, a buffer compartment, and a catholyte compartment configured with a cathode. An alkali ion conducting solid electrolyte configured to selectively transport alkali ions is positioned between the anolyte compartment and the buffer compartment. An alkali ion permeable separator is positioned between the buffer compartment and the catholyte compartment. The catholyte solution may include an alkali alcoholate and alcohol. The anolyte solution may include at least one alkali salt. The buffer compartment solution may include a soluble alkali salt and an alkali alcoholate in alcohol.

Time-Resolved Fluorescence Anisotropy of Bicyclo[1.1.1]pentane/Tolane-Based Molecular Rods Included in Tris(o-phenylenedioxy)cyclotriphosphazene (TPP).

PubMed

Cipolloni, Marco; Kaleta, Jiří; Mašát, Milan; Dron, Paul I; Shen, Yongqiang; Zhao, Ke; Rogers, Charles T; Shoemaker, Richard K; Michl, Josef

2015-04-23

We examine the fluorescence anisotropy of rod-shaped guests held inside the channels of tris( o -phenylenedioxy)cyclotriphosphazene (TPP) host nanocrystals, characterized by powder X-ray diffraction and solid state NMR spectroscopy. We address two issues: (i) are light polarization measurements on an aqueous colloidal solution of TPP nanocrystals meaningful, or is depolarization by scattering excessive? (ii) Can measurements of the rotational mobility of the included guests be performed at low enough loading levels to suppress depolarization by intercrystallite energy transfer? We find that meaningful measurements are possible and demonstrate that the long axis of molecular rods included in TPP channels performs negligible vibrational motion.

Highly efficient single-layer dendrimer light-emitting diodes with balanced charge transport

NASA Astrophysics Data System (ADS)

Anthopoulos, Thomas D.; Markham, Jonathan P. J.; Namdas, Ebinazar B.; Samuel, Ifor D. W.; Lo, Shih-Chun; Burn, Paul L.

2003-06-01

High-efficiency single-layer-solution-processed green light-emitting diodes based on a phosphorescent dendrimer are demonstrated. A peak external quantum efficiency of 10.4% (35 cd/A) was measured for a first generation fac-tris(2-phenylpyridine) iridium cored dendrimer when blended with 4,4'-bis(N-carbazolyl)biphenyl and electron transporting 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene at 8.1 V. A maximum power efficiency of 12.8 lm/W was measured also at 8.1 V and 550 cd/m2. These results indicate that, by simple blending of bipolar and electron-transporting molecules, highly efficient light-emitting diodes can be made employing a very simple device structure.

Amino Acid-Assisted Dehalogenation of Carbon Tetrachloride by Green Rust: Inhibition of Chloroform Production.

PubMed

Yin, Weizhao; Strobel, Bjarne W; B Hansen, Hans Christian

2017-03-21

Layered Fe II -Fe III hydroxides (green rusts, GRs) are promising reactants for reductive dechlorination of chlorinated solvents due to high reaction rates and the opportunity to inject reactive slurries of the compounds into contaminant plumes. However, it is necessary to develop strategies that reduce the formation of toxic byproducts such as chloroform (CF). In this study, carbon tetrachloride (CT) dehalogenation by the chloride form of GR (GR Cl ) was tested in the presence of glycine (GLY) and other selected amino acids. GLY, alanine (ALA), and serine (SER) all resulted in remarkable suppression of CF formation with only ∼10% of CF recovery while sarcosine (SAR) showed insignificant effects. For two nonamino acid buffers, TRIS had little effect while HEPES resulted in a 40 times lower rate constant compared to experiments in which no buffer was added. The Fe II complexing properties of the amino acids and buffers caused variable extents of GR Cl dissolution which was linearly correlated with CF suppression and dehalogenation rate. We hypothesize that the CF suppression seen for amino acids is caused by stabilization of carbene intermediates via the carbonyl group. Different effects on CF suppression and CT dehalogenation rate were expected because of the different structural and chemical properties of the amino acids.

BIOKID: Randomized controlled trial comparing bicarbonate and lactate buffer in biocompatible peritoneal dialysis solutions in children [ISRCTN81137991

PubMed Central

Nau, Barbara; Schmitt, Claus P; Almeida, Margarida; Arbeiter, Klaus; Ardissino, Gianluigi; Bonzel, Klaus E; Edefonti, Alberto; Fischbach, Michel; Haluany, Karin; Misselwitz, Joachim; Kemper, Markus J; Rönnholm, Kai; Wygoda, Simone; Schaefer, Franz

2004-01-01

Background Peritoneal dialysis (PD) is the preferred dialysis modality in children. Its major drawback is the limited technique survival due to infections and progressive ultrafiltration failure. Conventional PD solutions exert marked acute and chronic toxicity to local tissues. Prolonged exposure is associated with severe histopathological alterations including vasculopathy, neoangiogenesis, submesothelial fibrosis and a gradual loss of the mesothelial cell layer. Recently, more biocompatible PD solutions containing reduced amounts of toxic glucose degradation products (GDPs) and buffered at neutral pH have been introduced into clinical practice. These solutions contain lactate, bicarbonate or a combination of both as buffer substance. Increasing evidence from clinical trials in adults and children suggests that the new PD fluids may allow for better long-term preservation of peritoneal morphology and function. However, the relative importance of the buffer in neutral-pH, low-GDP fluids is still unclear. In vitro, lactate is cytotoxic and vasoactive at the concentrations used in PD fluids. The BIOKID trial is designed to clarify the clinical significance of the buffer choice in biocompatible PD fluids. Methods/design The objective of the study is to test the hypothesis that bicarbonate based PD solutions may allow for a better preservation of peritoneal transport characteristics in children than solutions containing lactate buffer. Secondary objectives are to assess any impact of the buffer system on acid-base status, peritoneal tissue integrity and the incidence and severity of peritonitis. After a run-in period of 2 months during which a targeted cohort of 60 patients is treated with a conventional, lactate buffered, acidic, GDP containing PD fluid, patients will be stratified according to residual renal function and type of phosphate binding medication and randomized to receive either the lactate-containing Balance solution or the bicarbonate-buffered Bicavera® solution for a period of 10 months. Patients will be monitored by monthly physical and laboratory examinations. Peritoneal equilibration tests, 24-h dialysate and urine collections will be performed 4 times. Peritoneal biopsies will be obtained on occasion of intraabdominal surgery. Changes in small solute transport rates, markers of peritoneal tissue turnover in the effluent, acid-base status and peritonitis rates and severity will be analyzed. PMID:15485574

Selective oxoanion separation using a tripodal ligand

DOEpatents

Custelcean, Radu; Moyer, Bruce A.; Rajbanshi, Arbin

2016-02-16

The present invention relates to urea-functionalized crystalline capsules self-assembled by sodium or potassium cation coordination and by hydrogen-bonding water bridges to selectively encapsulate tetrahedral divalent oxoanions from highly competitive aqueous alkaline solutions and methods using this system for selective anion separations from industrial solutions. The method involves competitive crystallizations using a tripodal tris(urea) functionalized ligand and, in particular, provides a viable approach to sulfate separation from nuclear wastes.

Enhanced Electron Affinity and Exciton Confinement in Exciplex-Type Host: Power Efficient Solution-Processed Blue Phosphorescent OLEDs with Low Turn-on Voltage.

PubMed

Ban, Xinxin; Sun, Kaiyong; Sun, Yueming; Huang, Bin; Jiang, Wei

2016-01-27

A benzimidazole/phosphine oxide hybrid 1,3,5-tris(1-(4-(diphenylphosphoryl)phenyl)-1H-benzo[d]imidazol-2-yl)benzene (TPOB) was newly designed and synthesized as the electron-transporting component to form an exciplex-type host with the conventional hole-transporting material tris(4-carbazoyl-9-ylphenyl)amine (TCTA). Because of the enhanced triplet energy and electron affinity of TPOB, the energy leakage from exciplex-state to the constituting molecule was eliminated. Using energy transfer from exciplex-state, solution-processed blue phosphorescent organic light-emitting diodes (PHOLEDs) achieved an extremely low turn-on voltage of 2.8 V and impressively high power efficiency of 22 lm W(-1). In addition, the efficiency roll-off was very small even at luminance up to 10 000 cd m(-2), which suggested the balanced charge transfer in the emission layer. This study demonstrated that molecular modulation was an effective way to develop efficient exciplex-type host for high performanced PHOLEDs.

Molecular structure, proton affinity and hydrogen bonds of (2-hydroxyethyl)amine-N-oxides: DFT, MP2 and FTIR study

NASA Astrophysics Data System (ADS)

Aksamentova, Tamara N.; Chipanina, Nina N.; Oznobikhina, Larisa P.; Adamovich, Sergei N.; Smirnov, Vladimir I.

2018-01-01

Tris- 1, bis- 2, and mono- 3 (2-hydroxyethyl)amine-N-oxides isomers, their protonated forms, and H-complexes with acids have been studied in gas phase and DMSO solution by the quantum chemical calculations using DFT and MP2 methods. It is found that the proton affinity of the endo isomers 1a-3a, exo isomers 1b-3b and epi isomer 1c depends on the number of the hydroxyethyl groups, steric factors and strengths of the intramolecular H-bonds OHṡṡṡON in 1a-3a and OHṡṡṡOH in 1b-3b. The peculiarities of formation of the hydrogen bonded and proton transfer complexes of tris(2-hydroxyethyl)amine-N-oxide with trifluoroacetic and 2-methylphenyloxyacetic acids are defined by 1 configuration, acid strength and solvent polarity. The structure of 1 and its complexes upon transition to solution was determined using FTIR spectroscopy.

Possible pore size effects on the state of tris(8-quinolinato)aluminum(III) (Alq3) adsorbed in mesoporous silicas and their temperature dependence.

PubMed

Tagaya, Motohiro; Ogawa, Makoto

2008-12-07

The states of tris(8-quinolinato)aluminum(III) (Alq3) adsorbed in mesoporous silicas with different pore sizes (2.5, 3.1 and 5.0 nm) were investigated. Alq3 was successfully occluded into the mesoporous silicas from solution and the adsorbed amount of Alq3 per BET surface area was effectively controlled by changing the added amount Alq3 to the solution. The state of Alq3 in the mesopore varied depending on the pore size as well as the adsorbed amount of Alq3 as revealed by variation of the photoluminescence spectra. The luminescence of the adsorbed Alq3 was found to be temperature-dependent, indicating the mobility of the adsorbed Alq3 to temperature variations. The temperature-dependence also depended on the pore size. The guest-guest interactions between Alq3 molecules as well as the host-guest interactions between Alq3 and the mesopore were controlled by the pore size.

Processing and characterisation of a novel electropolymerized silk fibroin hydrogel membrane

PubMed Central

Wang, Hai-Yan; Zhang, Yu-Qing

2014-01-01

Silk fibroin can be made into various forms of biocompatible medical materials, including hydrogel due to its excellent properties. Here, we report a novel method for the preparation of electropolymerized silk fibroin hydrogel membrane (ESFHM), which is formed on a nanoporous film as a barrier using a homemade device at a higher DC voltage. Regenerated silk fibroin solution in Tris buffer (pH 6.55–7.55) was added into a reservoir with a negative charge, and the silk molecules migrated toward the positive charge at 80VDC, resulting in the formation of the ESFHM on the barrier film. Barrier film with a MWCO of 10 kDa is favourable to the formation of the ESFHM. Semi-transparent ESFHM with a swelling ratio of 1056.4% predominantly consisted of a mixture of β-sheets and α-helix crystalline structures. SEM studies revealed that the ESFHM consisted of a 3D mesh structure woven by a chain of silk fibroin nanoparticles with a size of approximately 30 nanometres, similar to a pearl necklace. In vitro studies indicated that the ESFHM was degradable and was sufficient for cell adhesion and growth. Thus, ESFHM is a promising candidate for loading bioactive protein and appropriate cells, as artificial skin or for use in transplantation. PMID:25154713

Chemical Stability and Biological Properties of Plasma-Sprayed CaO-SiO2-ZrO2 Coatings

NASA Astrophysics Data System (ADS)

Liang, Ying; Xie, Youtao; Ji, Heng; Huang, Liping; Zheng, Xuebin

2010-12-01

In this work, calcia-stabilized zirconia powders were coated by silica derived from tetraethoxysilane (TEOS) hydrolysis. After calcining at 1400 °C, decalcification of calcia-stabilized zirconia by silica occurred and powders composed of Ca2SiO4, ZrO2, and CaZrO3 were prepared. We produced three kinds of powders with different Ca2SiO4 contents [20 wt.% (denoted as CZS2), 40 wt.% (denoted as CZS4), and 60 wt.% (denoted as CZS6)]. The obtained powders were sprayed onto Ti-6Al-4V substrates using atmospheric plasma spraying. The microstructure of the powders and coatings were analyzed. The dissolution rates of the coatings were assessed by monitoring the ions release and mass losses after immersion in Tris-HCl buffer solution. Results showed that the chemical stability of the coatings were significantly improved compared with pure calcium silicate coatings, and increased with the increase of Zr contents. The CZS4 coating showed not only good apatite-formation ability in simulated body fluid, but also well attachment and proliferation capability for the canine bone marrow stem cells. Results presented here indicate that plasma-sprayed CZS4 coating has medium dissolution rate and good biological properties, suggesting its potential use as bone implants.

Glucose buffer is suitable for blood group conversion with α-N acetylgalactosaminidase and α-galactosidase

PubMed Central

Gao, Hong-Wei; Li, Su-Bo; Bao, Guo-Qiang; Zhang, Xue; Li, Hui; Wang, Ying-Li; Tan, Ying-Xia; Ji, Shou-Ping; Gong, Feng

2014-01-01

Background It is well known that the buffer plays a key role in the enzymatic reaction involved in blood group conversion. In previous study, we showed that a glycine buffer is suitable for A to O or B to O blood group conversion. In this study, we investigated the use of 5% glucose and other buffers for A to O or B to O blood group conversion by α-N-acetylgalactosaminidase or α-galactosidase. Materials and methods We compared the binding ability of α-N-acetylgalactosaminidase/α-galactosidase with red blood cells (RBC) in different reaction buffers, such as normal saline, phosphate-buffered saline (PBS), a disodium hydrogen phosphate-based buffer (PCS), and 5% commercial glucose solution. The doses of enzymes necessary for the A/B to O conversion in different reaction buffers were determined and compared. The enzymes’ ability to bind to RBC was evaluated by western blotting, and routine blood typing and fluorescence activated cell sorting was used to evaluate B/A to O conversion efficiency. Results The A to O conversion efficiency in glucose buffer was similar to that in glycine buffer with the same dose (>0.06 mg/mL pRBC). B to O conversion efficiency in glucose buffer was also similar to that in glycine buffer with the same dose (>0.005 mg/mL pRBC). Most enzymes could bind with RBC in glycine or glucose buffer, but few enzymes could bind with RBC in PBS, PCS, or normal saline. Conclusion These results indicate that 5% glucose solution provides a suitable condition for enzymolysis, especially for enzymes combining with RBC. Meanwhile, the conversion efficiency of A/B to O was similar in glucose buffer and glycine buffer. Moreover, 5% glucose solution has been used for years in venous transfusion, it is safe for humans and its cost is lower. Our results do, therefore, suggest that 5% glucose solution could become a novel suitable buffer for A/B to O blood group conversion. PMID:24333060

Analysis of three variables in sampling solutions used to assay bacteria of hands: type of solution, use of antiseptic neutralizers, and solution temperature.

PubMed Central

Larson, E L; Strom, M S; Evans, C A

1980-01-01

Tests were performed using the sterile bag technique to determine the effects of type of sampling solution, use of antiseptic neutralizers, and solution temperature on the detection and quantitation of bacteria on hands. Using paired hand cultures, three sampling solutions were compared: quarter-strength Ringer solution, a phosphate buffer containing Triton X-100, and the same buffer containing antiseptic neutralizers. The phosphate buffer containing Triton X-100 was significantly better than quarter-strength Ringer solution in mean bacterial yield; the neutralizer-containing sampling solution was slightly better than Triton X-100-containing solution, although differences were not significant at the P = 0.05 level. Temperature (6 or 23 degrees C) of the sampling solution showed no consistent effect on bacterial yield from hands tested with the fluid containing neutralizers. PMID:7012171

Role of Buffers in Protein Formulations.

PubMed

Zbacnik, Teddy J; Holcomb, Ryan E; Katayama, Derrick S; Murphy, Brian M; Payne, Robert W; Coccaro, Richard C; Evans, Gabriel J; Matsuura, James E; Henry, Charles S; Manning, Mark Cornell

2017-03-01

Buffers comprise an integral component of protein formulations. Not only do they function to regulate shifts in pH, they also can stabilize proteins by a variety of mechanisms. The ability of buffers to stabilize therapeutic proteins whether in liquid formulations, frozen solutions, or the solid state is highlighted in this review. Addition of buffers can result in increased conformational stability of proteins, whether by ligand binding or by an excluded solute mechanism. In addition, they can alter the colloidal stability of proteins and modulate interfacial damage. Buffers can also lead to destabilization of proteins, and the stability of buffers themselves is presented. Furthermore, the potential safety and toxicity issues of buffers are discussed, with a special emphasis on the influence of buffers on the perceived pain upon injection. Finally, the interaction of buffers with other excipients is examined. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Contemporary reliance on bicarbonate acquisition predicts increased growth of seagrass Amphibolis antarctica in a high-CO2 world

PubMed Central

Burnell, Owen W.; Connell, Sean D.; Irving, Andrew D.; Watling, Jennifer R.; Russell, Bayden D.

2014-01-01

Rising atmospheric CO2 is increasing the availability of dissolved CO2 in the ocean relative to HCO3−. Currently, many marine primary producers use HCO3− for photosynthesis, but this is energetically costly. Increasing passive CO2 uptake relative to HCO3− pathways could provide energy savings, leading to increased productivity and growth of marine plants. Inorganic carbon-uptake mechanisms in the seagrass Amphibolis antarctica were determined using the carbonic anhydrase inhibitor acetazolamide (AZ) and the buffer tris(hydroxymethyl)aminomethane (TRIS). Amphibolis antarctica seedlings were also maintained in current and forecasted CO2 concentrations to measure their physiology and growth. Photosynthesis of A. antarctica was significantly reduced by AZ and TRIS, indicating utilization of HCO3−-uptake mechanisms. When acclimated plants were switched between CO2 treatments, the photosynthetic rate was dependent on measurement conditions but not growth conditions, indicating a dynamic response to changes in dissolved CO2 concentration, rather than lasting effects of acclimation. At forecast CO2 concentrations, seedlings had a greater maximum electron transport rate (1.4-fold), photosynthesis (2.1-fold), below-ground biomass (1.7-fold) and increase in leaf number (2-fold) relative to plants in the current CO2 concentration. The greater increase in photosynthesis (measured as O2 production) compared with the electron transport rate at forecasted CO2 concentration suggests that photosynthetic efficiency increased, possibly due to a decrease in photorespiration. Thus, it appears that the photosynthesis and growth of seagrasses reliant on energetically costly HCO3− acquisition, such as A. antarctica, might increase at forecasted CO2 concentrations. Greater growth might enhance the future prosperity and rehabilitation of these important habitat-forming plants, which have experienced declines of global significance. PMID:27293673

Contemporary reliance on bicarbonate acquisition predicts increased growth of seagrass Amphibolis antarctica in a high-CO2 world.

PubMed

Burnell, Owen W; Connell, Sean D; Irving, Andrew D; Watling, Jennifer R; Russell, Bayden D

2014-01-01

Rising atmospheric CO2 is increasing the availability of dissolved CO2 in the ocean relative to HCO3 (-). Currently, many marine primary producers use HCO3 (-) for photosynthesis, but this is energetically costly. Increasing passive CO2 uptake relative to HCO3 (-) pathways could provide energy savings, leading to increased productivity and growth of marine plants. Inorganic carbon-uptake mechanisms in the seagrass Amphibolis antarctica were determined using the carbonic anhydrase inhibitor acetazolamide (AZ) and the buffer tris(hydroxymethyl)aminomethane (TRIS). Amphibolis antarctica seedlings were also maintained in current and forecasted CO2 concentrations to measure their physiology and growth. Photosynthesis of A. antarctica was significantly reduced by AZ and TRIS, indicating utilization of HCO3 (-)-uptake mechanisms. When acclimated plants were switched between CO2 treatments, the photosynthetic rate was dependent on measurement conditions but not growth conditions, indicating a dynamic response to changes in dissolved CO2 concentration, rather than lasting effects of acclimation. At forecast CO2 concentrations, seedlings had a greater maximum electron transport rate (1.4-fold), photosynthesis (2.1-fold), below-ground biomass (1.7-fold) and increase in leaf number (2-fold) relative to plants in the current CO2 concentration. The greater increase in photosynthesis (measured as O2 production) compared with the electron transport rate at forecasted CO2 concentration suggests that photosynthetic efficiency increased, possibly due to a decrease in photorespiration. Thus, it appears that the photosynthesis and growth of seagrasses reliant on energetically costly HCO3 (-) acquisition, such as A. antarctica, might increase at forecasted CO2 concentrations. Greater growth might enhance the future prosperity and rehabilitation of these important habitat-forming plants, which have experienced declines of global significance.

Use of the short-term inflammatory response in the mouse peritoneal cavity to assess the biological activity of leached vitreous fibers.

PubMed Central

Donaldson, K; Addison, J; Miller, B G; Cullen, R T; Davis, J M

1994-01-01

We used a special-purpose glass microfiber sample, Johns-Manville Code 100/475, to study the effects of various acid and alkali treatments on biological activity as assessed by inflammation in the mouse peritoneal cavity, the leaching of Si, and the phase contrast optical microscopy (PCOM) fiber number. We used mild and medium treatments with oxalic acid and Tris buffer and harsh treatment with concentrated HCl and NaOH. Mild oxalic acid and Tris treatment for 2 weeks had no effect on any of the end-points, but prolonging the mild oxalic acid treatment time to 2 months reduced the biological activity and the fiber number. Medium oxalic acid treatment reduced the biological activity and the fiber number and caused a loss of Si. Medium Tris alkali treatment reduced the PCOM-countable fibers and the biological activity but did not cause a substantial loss of Si. Harsh treatment with strong HCl did not affect the fiber number or cause leaching but the biological activity was reduced; strong NaOH reduced the fiber number and biological activity, and caused marked leaching of Si. The medium oxalic acid conditions (pH 1.4) were more acid than those found in lung cells but produced the same effects (reduction in fiber number and biological activity) as the more physiological mild treatment (pH 4.0), when prolonged. This study suggests that medium oxalic acid treatment can be used as a short-term assay to compare loss of Si, reduction in fiber number, and change in biological activity of vitreous fibers.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7882922

A Class of Rigid Linker-bearing Glucosides for Membrane Protein Structural Study.

PubMed

Sadaf, Aiman; Mortensen, Jonas S; Capaldi, Stefano; Tikhonova, Elena; Hariharan, Parameswaran; de Castro Ribeiro, Orquidea; Loland, Claus J; Guan, Lan; Byrne, Bernadette; Chae, Pil Seok

2016-03-01

Membrane proteins are amphipathic bio-macromolecules incompatible with the polar environments of aqueous media. Conventional detergents encapsulate the hydrophobic surfaces of membrane proteins allowing them to exist in aqueous solution. Membrane proteins stabilized by detergent micelles are used for structural and functional analysis. Despite the availability of a large number of detergents, only a few agents are sufficiently effective at maintaining the integrity of membrane proteins to allow successful crystallization. In the present study, we describe a novel class of synthetic amphiphiles with a branched tail group and a triglucoside head group. These head and tail groups were connected via an amide or ether linkage by using a tris(hydroxylmethyl)aminomethane (TRIS) or neopentyl glycol (NPG) linker to produce TRIS-derived triglucosides (TDTs) and NPG-derived triglucosides (NDTs), respectively. Members of this class conferred enhanced stability on target membrane proteins compared to conventional detergents. Because of straightforward synthesis of the novel agents and their favourable effects on a range of membrane proteins, these agents should be of wide applicability to membrane protein science.

A Class of Rigid Linker-bearing Glucosides for Membrane Protein Structural Study

PubMed Central

Sadaf, Aiman; Mortensen, Jonas S.; Capaldi, Stefano; Tikhonova, Elena; Hariharan, Parameswaran; de Castro Ribeiro, Orquidea; Loland, Claus J; Guan, Lan; Byrne, Bernadette

2015-01-01

Membrane proteins are amphipathic bio-macromolecules incompatible with the polar environments of aqueous media. Conventional detergents encapsulate the hydrophobic surfaces of membrane proteins allowing them to exist in aqueous solution. Membrane proteins stabilized by detergent micelles are used for structural and functional analysis. Despite the availability of a large number of detergents, only a few agents are sufficiently effective at maintaining the integrity of membrane proteins to allow successful crystallization. In the present study, we describe a novel class of synthetic amphiphiles with a branched tail group and a triglucoside head group. These head and tail groups were connected via an amide or ether linkage by using a tris(hydroxylmethyl)aminomethane (TRIS) or neopentyl glycol (NPG) linker to produce TRIS-derived triglucosides (TDTs) and NPG-derived triglucosides (NDTs), respectively. Members of this class conferred enhanced stability on target membrane proteins compared to conventional detergents. Because of straightforward synthesis of the novel agents and their favourable effects on a range of membrane proteins, these agents should be of wide applicability to membrane protein science. PMID:27110345

Time-resolved EPR study on the photoexcited triplet state of the electron-donor-acceptor complex formed in the system of fac-tris[2-(4-octyl-phenyl) pyridine] iridium(III) and tetracene.

PubMed

Zhebin, Fu; Shuhei, Yoshioka; Hisao, Murai

2014-01-09

The physical properties of the phosphorescent organic light-emitting diode material fac-tris(phenylpyridine) iridium(III), Ir(ppy)3, have been reported with experimental and theoretical studies. Here, the photochemical properties of the excited triplet state of partially modified fac-tris[2-(4-octyl-phenyl) pyridine] iridium(III), Ir(C8ppy)3, were investigated using time-resolved electron paramagnetic resonance (tr-EPR) and optical methods by adding tetracene in the toluene solution. The tr-EPR observation at 77 K revealed the following two species: the excited triplet state of tetracene and another triplet species with zero field splitting parameters of |D| = 0.088 cm(-1) and |E| = 0.018 cm(-1) with characteristic spin polarization. The latter species was assigned to the electron-donor-acceptor (EDA) complex formed between Ir(C8ppy)3 and tetracene. The mechanism of formation and the properties of this EDA complex, including the information on the principal axes of (3)Ir(C8ppy)3*, are discussed.

Optimization of a model of red blood cells for the study of anti-oxidant drugs, in terms of concentration of oxidant and phosphate buffer.

PubMed

Bureau, A; Lahet, J-J; Lenfant, F; Bouyer, F; Petitjean, M; Chaillot, B; Freysz, M

2005-08-01

The aggression of erythrocytes by an oxidative stress induces hemolysis. This paper aims to valid a model of erythrocytes in terms of composition of the phosphate buffer solution and of concentration of a well-known oxidant, AAPH. Three compositions of phosphate buffer solution are mixed with three concentrations of oxidant. The influence of these two parameters on hemolysis is independently studied by a variance analysis and a Kruskal-Wallis test when ANOVA is not available. The hemolysis rate increases with time at fixed oxidant concentration, but is not influenced by the composition of the buffer solution. The highest hemolysis rate, 90%, was only measured within 2 h with the highest oxidant concentration. If we retain this concentration of oxidant, the lower concentration of the buffer can by eliminated by a significant less hemolysis and the highest concentration of the buffer can by chosen in regard of the better precision for a similar hemolysis compared to the mean buffer. We hope to study the effect of anti-oxidant agent with such a model of erythrocytes.

Effects of Carbon in Flooded Paddy Soils: Implications for Microbial Activity and Arsenic Mobilization

NASA Astrophysics Data System (ADS)

Avancha, S.; Boye, K.

2014-12-01

In the Mekong delta in Cambodia, naturally occurring arsenic (originating from erosion in the Himalaya Mountains) in paddy soils is mobilized during the seasonal flooding. As a consequence, rice grown on the flooded soils may take up arsenic and expose people eating the rice to this carcinogenic substance. Microbial activity will enhance or decrease the mobilization of arsenic depending on their metabolic pathways. Among the microbes naturally residing in the soil are denitrifying bacteria, sulfate reducers, metal reducers (Fe, Mn), arsenic reducers, methanogens, and fermenters, whose activity varies based on the presence of oxygen. The purpose of the experiment was to assess how different amendments affect the microbial activity and the arsenic mobilization during the transition from aerobic to anaerobic metabolism after flooding of naturally contaminated Cambodian soil. In a batch experiment, we investigated how the relative metabolic rate of naturally occurring microbes could vary with different types of organic carbon. The experiment was designed to measure the effects of various sources of carbon (dried rice straw, charred rice straw, manure, and glucose) on the microbial activity and arsenic release in an arsenic-contaminated paddy soil from Cambodia under flooded conditions. All amendments were added based on the carbon content in order to add 0.036 g of carbon per vial. The soil was flooded with a 10mM TRIS buffer solution at pH 7.04 in airtight 25mL serum vials and kept at 25 °C. We prepared 14 replicates per treatment to sample both gas and solution. On each sampling point, the solution replicates were sampled destructively. The gas replicates continued on and were sampled for both gas and solution on the final day of the experiment. We measured pH, total arsenic, methane, carbon dioxide, and nitrous oxide at 8 hours, 1.5 days, 3.33 days, and 6.33 days from the start of the experiment.

Reference measurement procedure for total glycerides by isotope dilution GC-MS.

PubMed

Edwards, Selvin H; Stribling, Shelton L; Pyatt, Susan D; Kimberly, Mary M

2012-04-01

The CDC's Lipid Standardization Program established the chromotropic acid (CA) reference measurement procedure (RMP) as the accuracy base for standardization and metrological traceability for triglyceride testing. The CA RMP has several disadvantages, including lack of ruggedness. It uses obsolete instrumentation and hazardous reagents. To overcome these problems the CDC developed an isotope dilution GC-MS (ID-GC-MS) RMP for total glycerides in serum. We diluted serum samples with Tris-HCl buffer solution and spiked 200-μL aliquots with [(13)C(3)]-glycerol. These samples were incubated and hydrolyzed under basic conditions. The samples were dried, derivatized with acetic anhydride and pyridine, extracted with ethyl acetate, and analyzed by ID-GC-MS. Linearity, imprecision, and accuracy were evaluated by analyzing calibrator solutions, 10 serum pools, and a standard reference material (SRM 1951b). The calibration response was linear for the range of calibrator concentrations examined (0-1.24 mmol/L) with a slope and intercept of 0.717 (95% CI, 0.7123-0.7225) and 0.3122 (95% CI, 0.3096-0.3140), respectively. The limit of detection was 14.8 μmol/L. The mean %CV for the sample set (serum pools and SRM) was 1.2%. The mean %bias from NIST isotope dilution MS values for SRM 1951b was 0.7%. This ID-GC-MS RMP has the specificity and ruggedness to accurately quantify total glycerides in the serum pools used in the CDC's Lipid Standardization Program and demonstrates sufficiently acceptable agreement with the NIST primary RMP for total glyceride measurement.

Biphasic reduction model for predicting the impacts of dye-bath constituents on the reduction of tris-azo dye Direct Green-1 by zero valent iron (Fe0).

PubMed

Kumar, Raja; Sinha, Alok

2017-02-01

Influence of common dye-bath additives, namely sodium chloride, ammonium sulphate, urea, acetic acid and citric acid, on the reductive decolouration of Direct Green 1 dye in the presence of Fe 0 was investigated. Organic acids improved dye reduction by augmenting Fe 0 corrosion, with acetic acid performing better than citric acid. NaCl enhanced the reduction rate by its 'salting out' effect on the bulk solution and by Cl - anion-mediated pitting corrosion of iron surface. (NH 4 ) 2 SO 4 induced 'salting out' effect accompanied by enhanced iron corrosion by SO 4 2- anion and buffering effect of NH 4 + improved the reduction rates. However, at 2g/L (NH 4 ) 2 SO 4 concentration, complexating of SO 4 2- with iron oxides decreased Fe 0 reactivity. Urea severely compromised the reduction reaction, onus to its chaotropic and 'salting in' effect in solution, and due to it masking the Fe 0 surface. Decolouration obeyed biphasic reduction kinetics (R 2 >0.993 in all the cases) exhibiting an initial rapid phase, when more than 95% dye reduction was observed, preceding a tedious phase. Maximum rapid phase reduction rate of 0.955/min was observed at pH2 in the co-presence of all dye-bath constituents. The developed biphasic model reckoned the influence of each dye-bath additive on decolouration and simulated well with the experimental data obtained at pH2. Copyright © 2016. Published by Elsevier B.V.

Time-Resolved Fluorescence Anisotropy of Bicyclo[1.1.1]pentane/Tolane-Based Molecular Rods Included in Tris(o-phenylenedioxy)cyclotriphosphazene (TPP)

PubMed Central

2015-01-01

We examine the fluorescence anisotropy of rod-shaped guests held inside the channels of tris(o-phenylenedioxy)cyclotriphosphazene (TPP) host nanocrystals, characterized by powder X-ray diffraction and solid state NMR spectroscopy. We address two issues: (i) are light polarization measurements on an aqueous colloidal solution of TPP nanocrystals meaningful, or is depolarization by scattering excessive? (ii) Can measurements of the rotational mobility of the included guests be performed at low enough loading levels to suppress depolarization by intercrystallite energy transfer? We find that meaningful measurements are possible and demonstrate that the long axis of molecular rods included in TPP channels performs negligible vibrational motion. PMID:25937858

Corneal epithelial cell biocompatibility to silicone hydrogel and conventional hydrogel contact lens packaging solutions

PubMed Central

Tanti, N.C.; Jones, L.; Sheardown, H.

2010-01-01

Purpose Although all contact lenses (CLs) are applied initially to the eye directly from a packaging solution, little is known about the effects of these solutions on human corneal epithelial cells (HCECs). Due to the porous nature of CL materials, they have the potential to sorb components of the packaging solution during storage, which could then be subsequently released upon insertion of the CL on the eye. The purpose of this study was to investigate the effect of various packaging solutions on HCECs, using an in vitro model. Methods An in vitro assay was developed whereby various silicone hydrogels and conventional, poly-2-hydroxyethylmethacrylate  (polyHEMA)-based lens materials were removed directly from their packaging and then incubated for up to 24 h with HCECs. The effect of the retained and released packaging solution components on HCECs was assessed by measuring cell viability, adhesion phenotype, and apoptosis. Results Incubation of HCECs with CLs stored in borate-buffered packaging solutions resulted in a significant reduction in cell viability. Adherent cells incubated with these CLs also exhibited reduced levels of β1 and α3 integrin. Soaking borate-buffered packaged CLs in PBS before cell incubation resolved viability and integrin expression in all cases, with the exception of galyfilcon A and balafilcon A, from which a 20% reduction in cell viability was still observed. In comparison, CLs stored in phosphate-buffered packaging solutions had cellular viability and expression of integrins similar to control cells (cells incubated in the absence of a lens). When incubated with cells at a 10% concentration in serum-free medium, borate-buffered packaging solutions and borate-containing saline (Unisol 4) significantly reduced cell viability and integrin expression. Neither caspase activation nor annexin V binding was observed on cells following exposure to borate buffer solution. However, a significant decrease in reactive oxygen species was observed at 24 h. These latter results suggest that in vitro exposure to low concentration of borate/boric acid results in cell dysfunction, leading to necrosis rather than apoptosis. Conclusions Borate-buffered packaging solutions were shown to adversely affect the viability and integrin expression of HCECs in vitro. When used in ophthalmic packaging solutions, the antimicrobial properties of borate buffer may be outweighed by its relatively cytotoxic effects on cells. PMID:20169012

Corneal epithelial cell biocompatibility to silicone hydrogel and conventional hydrogel contact lens packaging solutions.

PubMed

Gorbet, M B; Tanti, N C; Jones, L; Sheardown, H

2010-02-19

Although all contact lenses (CLs) are applied initially to the eye directly from a packaging solution, little is known about the effects of these solutions on human corneal epithelial cells (HCECs). Due to the porous nature of CL materials, they have the potential to sorb components of the packaging solution during storage, which could then be subsequently released upon insertion of the CL on the eye. The purpose of this study was to investigate the effect of various packaging solutions on HCECs, using an in vitro model. An in vitro assay was developed whereby various silicone hydrogels and conventional, poly-2-hydroxyethylmethacrylate (polyHEMA)-based lens materials were removed directly from their packaging and then incubated for up to 24 h with HCECs. The effect of the retained and released packaging solution components on HCECs was assessed by measuring cell viability, adhesion phenotype, and apoptosis. Incubation of HCECs with CLs stored in borate-buffered packaging solutions resulted in a significant reduction in cell viability. Adherent cells incubated with these CLs also exhibited reduced levels of beta(1) and alpha(3) integrin. Soaking borate-buffered packaged CLs in PBS before cell incubation resolved viability and integrin expression in all cases, with the exception of galyfilcon A and balafilcon A, from which a 20% reduction in cell viability was still observed. In comparison, CLs stored in phosphate-buffered packaging solutions had cellular viability and expression of integrins similar to control cells (cells incubated in the absence of a lens). When incubated with cells at a 10% concentration in serum-free medium, borate-buffered packaging solutions and borate-containing saline (Unisol 4) significantly reduced cell viability and integrin expression. Neither caspase activation nor annexin V binding was observed on cells following exposure to borate buffer solution. However, a significant decrease in reactive oxygen species was observed at 24 h. These latter results suggest that in vitro exposure to low concentration of borate/boric acid results in cell dysfunction, leading to necrosis rather than apoptosis. Borate-buffered packaging solutions were shown to adversely affect the viability and integrin expression of HCECs in vitro. When used in ophthalmic packaging solutions, the antimicrobial properties of borate buffer may be outweighed by its relatively cytotoxic effects on cells.

Combined Microfluidic-Eectric Diffused Mixing of Living Cells in Continuous Flow

NASA Astrophysics Data System (ADS)

Ming-Wen Wang,

2010-02-01

The mixing process is a crucially important stage in the operation of biological and chemical microfluidic devices. If the mixing is inadequate, reactants do not fully interact with each other, and the device may not operate properly. This paper describes a simplified microfluidic mixer (different from a chaotic mixer) which can uniformly mix a buffer solution with living cells by applying an AC electric charge. Diffusion of the living cells into the buffer solution occurs rapidly following the interface of the flow stream with the electric charge; no further agitating step is needed. To accomplish this, an asymmetric pair of electrodes was integrated at the inlets of the buffer solution and the cells fluid. When the buffer solution and the cells fluid were introduced into one flow path, they remained limited to that flow stream. When the electrodes were charged, however, the cells in a short distance were efficiently moved into the solution flow, and the original fluids were mixed. The mixing efficiency depends on the polarizability of the cells, and this in turn is governed by the dielectric properties of the cells, the medium, and the solvent. This micro device, capable of efficiently mixing living cells with a buffer solution, may potentially allow biological mixing to be done outside of hospitals, in facilities without biological analyzing instruments.

Redox buffered hydrofluoric acid etchant for the reduction of galvanic attack during release etching of MEMS devices having noble material films

DOEpatents

Hankins, Matthew G [Albuquerque, NM

2009-10-06

Etchant solutions comprising a redox buffer can be used during the release etch step to reduce damage to the structural layers of a MEMS device that has noble material films. A preferred redox buffer comprises a soluble thiophosphoric acid, ester, or salt that maintains the electrochemical potential of the etchant solution at a level that prevents oxidation of the structural material. Therefore, the redox buffer preferentially oxidizes in place of the structural material. The sacrificial redox buffer thereby protects the exposed structural layers while permitting the dissolution of sacrificial oxide layers during the release etch.

Thermodynamic characteristics of the interaction between nicotinic acid and phenylalanine in an aqueous buffer solution at 298 K

NASA Astrophysics Data System (ADS)

Badelin, V. G.; Tyunina, E. Yu.; Mezhevoi, I. N.; Tarasova, G. N.

2013-08-01

The interaction between L-phenylalanine and nicotinic acid is studied by solution calorimetry in an aqueous buffer solution (pH 7.35) at different ratios of the reagents. Experimental data on the enthalpy of dissolution of amino acid in the buffer solution of nicotinic acid at 298.15 K are calculated. The values of thermodynamic parameters for the complexation of L-phenylalanine with nicotinic acid are calculated. It is shown that the formation of a 1: 2 molecular complex is stabilized by the entropy factor due to the dominant role of the dehydration effect of initial reagents.

Test of the mechanism of UV-induced K/sup +/ efflux

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murphy, T.M.; Huerta, A.J.

1987-04-01

UV radiation and certain plant pathogens stimulate a net efflux of K/sup +/ from cultured plant cells. Many aspects of the efflux are uncertain, including the counterion(s) involved. In the case of UV irradiation of rose cells, Murphy and Wilson suggest a coordinate loss of K/sup +/ and HCO/sub 3//sup -/; in contrast, Atkinson et al. suggest that treatment of tobacco cells with Erwinia pectate lyase introduces a counterflux of K/sup +/ and H/sup +/. In respiring cells, the cytoplasm and medium are buffered by respiratory CO/sub 2/, and it is difficult to distinguish between the two mechanisms. Still, themore » two models predict different influences of external pH on the rate of K/sup +/ flux. The authors have found that increasing pH from 4 to 8 by use of MES-TRIS buffer, pH state, or controlled external CO/sub 2/ concentration does not significantly decrease the rate of UV-induced K/sup +/ efflux. This evidence does not support the application of the K/sup +//H/sup +/ counterflux model to the case of the UV-irradiated rose cells.« less

Degradation of small-molecule organic solar cells

NASA Astrophysics Data System (ADS)

Song, Q. L.; Wang, M. L.; Obbard, E. G.; Sun, X. Y.; Ding, X. M.; Hou, X. Y.; Li, C. M.

2006-12-01

Small-molecule organic solar cells with a structure of indium tin oxide (ITO)tris-8-hydroxy-quinolinato aluminum (Alq3) (2nm)fullerene (C60) (40nm)\\copper phthalocyanine (CuPc) (32nm)Au (40nm) were fabricated. The shelf lifetime of unencapsulated devices was over 1500h, and the power conversion efficiency reached 0.76% under AM1.5G (air mass 1.5 global) 75mW/cm2. The long lifetime was attributed to the inverted structure compared to the conventional ITO CuPcC60bufferAl structure since the former could effectively protect C60 from the diffusion of oxygen and modify interfacial electrical properties. The introduction of a 2nm Alq3 layer into the cells enhanced the power conversion efficiency by more than 20 times. The presence of the thin Alq3 film on the ITO substrate lowered the substrate work function and hence increased the electric field in the organic layers, which was beneficial to the collection of free carriers. The reasons for the degradation of such kind of organic solar cells are analyzed in detail.

Preparation and properties of an immobilized pectinlyase for the treatment of fruit juices.

PubMed

Busto, M D; García-Tramontín, K E; Ortega, N; Perez-Mateos, M

2006-09-01

Pectinlyase, present in different commercial pectinases used in juice technology, was immobilized on alginate beads. The optimal conditions were: 0.17 g alginate ml(-1), 1.2% (w/v or v/v) enzyme concentration and acetic-HCl/glycine-HCl buffer at pH 3.6 or tris-HCl/imidazole buffer at pH 6.4. Maximum percentage of immobilization (10.6%) was obtained with Rapidase C80. Kinetic parameters of free and immobilized pectinlyase were also determined. The pH and temperature at which activity of soluble and immobilized enzyme was maximum were 7.2 and 55 degrees C. Thermal stability was not significantly altered by immobilization, especially at 40 degrees C, showing two periods of different stability. Free and immobilized preparation reduced the viscosity of highly esterified pectin from 1.09 to 0.70 and 0.72 mm(2) s(-1), respectively, after 30 min at 40 degrees C. Furthermore, the immobilized enzyme could be re-used through 4 cycles and the efficiency loss in viscosity reduction was found to be only 9.2%.

Isolation of Active Mitochondria From Tomato Fruit 1

PubMed Central

Ku, Han San; Pratt, Harlan K.; Spurr, Arthur R.; Harris, William M.

1968-01-01

An improved method for isolating mitochondria from tomato fruit (Lycopersicon esculentum Mill.) is described. The fruit is chilled, and the tissue of the fruit wall cut by hand into very thin slices with a razor blade while immersed in a buffer containing 0.4 m sucrose, 2 mm MgCl2, 8 mm EDTA, 4 mm cysteine, 10 mm KCl, 0.5 mg per ml bovine serum albumin 50 mm tris-HCl, pH 7.6. The pH is monitored and kept within the range of 7.0 to 7.2 by dropwise addition of 1 n KOH during cutting. The tissue is strained through 8 layers of cheesecloth and centrifuged at 2000 × g for 15 minutes. The supernatant is then centrifuged at 11,000 × g for 20 minutes, and the sediment is washed once with a medium containing 0.4 m sucrose, 10 mm KCl, 1 mm MgCl2, 10 mm tris-HCl, 10 mm KH2PO4 and bovine serum albumin (0.5 mg per ml), pH 7.2. Electron microscope studies show that this method gives homogeneous, relatively intact mitochondria; they have a higher respiratory control ratio than those reported by other workers. The method was also tested successfully on fruits of cantaloupe and `Honey Dew' melon. Images PMID:16656857

Effect of IDA and TREN chelating agents and buffer systems on the purification of human IgG with immobilized nickel affinity membranes.

PubMed

Ribeiro, Mariana Borsoi; Vijayalakshmi, Mookambesvaran; Todorova-Balvay, Daniele; Bueno, Sonia Maria Alves

2008-01-01

The purification of IgG from human plasma was studied by comparing two affinity membranes complexed with Ni(II), prepared by coupling iminodiacetic acid (IDA) and Tris(2-aminoethyl)amine (TREN) to poly(ethylenevinyl alcohol), PEVA, hollow fiber membranes. The Ni(II)-TREN-PEVA hollow fiber membrane had lower capacity for human IgG than the complex Ni(II)-IDA-PEVA, but with similar selectivity. The IgG in peak fractions eluted from the Ni(II)-IDA-PEVA with a stepwise concentration gradient of Tris-HCl pH 7.0 (100-700 mM) reached a purity of 98% (based on IgG, IgM, IgA, albumin, and transferrin nephelometric analysis). Adsorption IgG data at different temperatures (4-37 degrees C) were analyzed using Langmuir model resulting in a calculated maximum capacity at 25 degrees C of 204.6 mg of IgG/g of dry membrane. Decrease in Kd with increasing temperature (1.7x10(-5) to 5.3x10(-6) M) indicated an increase in affinity with increased temperature. The positive value of enthalpy change (26.2 kJ/mol) indicated that the adsorption of IgG in affinity membrane is endothermic. Therefore, lower temperature induces adsorption as verified experimentally.

An evaluation of MES (2(N-Morpholino)ethanesulfonic acid) and Amberlite IRC-50 as pH buffers for nutrient solution studies

NASA Technical Reports Server (NTRS)

Bugbee, B. G.; Salisbury, F. B.

1985-01-01

All buffering agents used to stabilize pH in hydroponic research have disadvantages. Inorganic buffers are absorbed and may become phytotoxic. Solid carbonate salts temporarily mitigate decreasing pH but provide almost no protection against increasing pH, and they alter nutrient absorption. Exchange resins are more effective, but we find that they remove magnesium and manganese from solution. We have tested 2(N-Morpholino)ethanesulfonic acid (MES) as a buffering agent at concentrations of 1 and 10 mol m-3 (1 and 10 mM) with beans, corn, lettuce, tomatoes, and wheat. MES appears to be biologically inert and does not interact significantly with other solution ions. Relative growth rates among controls and MES treatments were nearly identical for each species during the trial period. The pH was stabilized by 1 mol m-3 MES. This buffer warrants further consideration in nutrient research.

The Determination of the pH of Standard Buffer Solution: A Laboratory Experiment.

ERIC Educational Resources Information Center

Harris, K. R.

1985-01-01

Describes an experiment which shows: (1) how measurements of the reaction electromotive force for the cell (Pt/glass/NaCl(aq,m),buffer/AgCl/Ag/Pt) can be utilized in determining the absolute pH of the buffer; and (2) the demonstration of the use of the Debye-Huckel model of an electrolyte solution in solving an important electrochemical problem.…

Role of copper oxides in contact killing of bacteria.

PubMed

Hans, Michael; Erbe, Andreas; Mathews, Salima; Chen, Ying; Solioz, Marc; Mücklich, Frank

2013-12-31

The potential of metallic copper as an intrinsically antibacterial material is gaining increasing attention in the face of growing antibiotics resistance of bacteria. However, the mechanism of the so-called "contact killing" of bacteria by copper surfaces is poorly understood and requires further investigation. In particular, the influences of bacteria-metal interaction, media composition, and copper surface chemistry on contact killing are not fully understood. In this study, copper oxide formation on copper during standard antimicrobial testing was measured in situ by spectroscopic ellipsometry. In parallel, contact killing under these conditions was assessed with bacteria in phosphate buffered saline (PBS) or Tris-Cl. For comparison, defined Cu2O and CuO layers were thermally generated and characterized by grazing incidence X-ray diffraction. The antibacterial properties of these copper oxides were tested under the conditions used above. Finally, copper ion release was recorded for both buffer systems by inductively coupled plasma atomic absorption spectroscopy, and exposed copper samples were analyzed for topographical surface alterations. It was found that there was a fairly even growth of CuO under wet plating conditions, reaching 4-10 nm in 300 min, but no measurable Cu2O was formed during this time. CuO was found to significantly inhibit contact killing, compared to pure copper. In contrast, thermally generated Cu2O was essentially as effective in contact killing as pure copper. Copper ion release from the different surfaces roughly correlated with their antibacterial efficacy and was highest for pure copper, followed by Cu2O and CuO. Tris-Cl induced a 10-50-fold faster copper ion release compared to PBS. Since the Cu2O that primarily forms on copper under ambient conditions is as active in contact killing as pure copper, antimicrobial objects will retain their antimicrobial properties even after oxide formation.

A Novel Protocol for Decoating and Permeabilizing Bacterial Spores for Epifluorescent Microscopy

NASA Technical Reports Server (NTRS)

LaDuc, Myron T.; Mohapatra, Bidyut

2014-01-01

Based on previously reported procedures for permeabilizing vegetative bacterial cells, and numerous trial-and-error attempts with bacterial endospores, a protocol was developed for effectively permeabilizing bacterial spores, which facilitated the applicability of fluorescent in situ hybridization (FISH) microscopy. Bacterial endospores were first purified from overgrown, sporulated suspensions of B. pumilus SAFR-032. Purified spores at a concentration of approx equals 10 million spores/mL then underwent proteinase-K treatment, in a solution of 468.5 µL of 100 mM Tris-HCl, 30 µL of 10% SDS, and 1.5 microL of 20 mg/mL proteinase-K for ten minutes at 35 ºC. Spores were then harvested by centrifugation (15,000 g for 15 minutes) and washed twice with sterile phosphate-buffered saline (PBS) solution. This washing process consisted of resuspending the spore pellets in 0.5 mL of PBS, vortexing momentarily, and harvesting again by centrifugation. Treated and washed spore pellets were then resuspended in 0.5 mL of decoating solution, which consisted of 4.8 g urea, 3 mL Milli-Q water, 1 mL 0.5M Tris, 1 mL 1M dithiothreitol (DTT), and 2 mL 10% sodium-dodecylsulfate (SDS), and were incubated at 65 ºC for 15 minutes while being shaken at 165 rpm. Decoated spores were then, once again, washed twice with sterile PBS, and subjected to lysozyme/mutanolysin treatment (7 mg/mL lysozyme and 7U mutanolysin) for 15 minutes at 35 C. Spores were again washed twice with sterile PBS, and spore pellets were resuspended in 1-mL of 2% SDS. This treatment, facilitating inner membrane permeabilization, lasted for ten minutes at room temperature. Permeabilized spores were washed two final times with PBS, and were resuspended in 200 mkcroL of sterile PBS. At this point, the spores were permeable and ready for downstream processing, such as oligonucleotideprobe infiltration, hybridization, and microscopic evaluation. FISH-microscopic imagery confirmed the effective and efficient (˜50% successful permeabilization and recovery) permeabilization of numerous spore preparations. The novelty of the technology developed here is in its applicability to bacterial endospores. While protocols abound for the effective permeabilization of bacterial, archaeal, and eukaryotic vegetative cells, there are no such reliable methods for decoating and permeabilizing bacterial endospores in a manner that is amenable to downstream FISH microscopic analyses. This innovation enables the direct visualization and enumeration of spores via FISH-based microscopic techniques, circumventing the complications that accompany previously required germination regimes. The synergistic enzymatic weakening of the many spore layers facilitates a structural compromise that is just enough to render the spores permeable without degrading the spore to a level, which precludes it from recognition.

Ion-solvation structure and battery electrode characteristics of nonflammable organic electrolytes based on tris(trifluoroethyl)phosphate dissolving lithium salts.

PubMed

Todorov, Yanko Marinov; Fujii, Kenta; Yoshimoto, Nobuko; Hirayama, Daisuke; Aoki, Masahiro; Mimura, Hideyuki; Morita, Masayuki

2017-11-29

The structure and properties of lithium salt solutions based on tris(2,2,2-trifluoroethyl)phosphate (TFEP) solvent have been studied to design a safer electrolyte system for large-sized lithium-ion battery applications. Influences of the ionic structure on the polarization behavior of the LiCoO 2 (LCO) positive electrode were investigated. The ionic conductivity and viscosity of the solution consisting of lithium salts dissolved in TFEP, LiX/TFEP (X = PF 6 , BF 4 and TFSA) (TFSA = (CF 3 SO 2 ) 2 N), were measured. The results suggest that the ion-solvation structure greatly depends on the anionic species in the salt. Spectroscopic measurements also support the conclusion that the Li + -solvation structure varies with the lithium salts. The differences in the ionic structure of LiX/TFEP influence the electrochemical oxidation potential of the solution and the polarization behavior of the LCO electrode. The overvoltage for Li-desertion/insertion from/into LCO in LiX/TFEP, being much higher than that observed in conventional LIB electrolyte solutions, shows the order of BF 4 < PF 6 < TFSA. The addition of ethylene carbonate (EC) to LiX/TFEP increases the ionic conductivity, which is probably caused by changes in the Li + -solvation structure in TFEP. The overvoltage for the Li-desertion/insertion of LCO is much lowered by the addition of EC to LiX/TFEP.

A study of different buffers to maximize viability of an oral Shigella vaccine.

PubMed

Chandrasekaran, Lakshmi; Lal, Manjari; Van De Verg, Lillian L; Venkatesan, Malabi M

2015-11-17

Live, whole cell killed and subunit vaccines are being developed for diarrheal diseases caused by V. cholerae, Shigella species, ETEC, and Campylobacter. Some of these vaccines can be administered orally since this route best mimics natural infection. Live vaccines administered orally have to be protected from the harsh acidic gastric environment. Milk and bicarbonate solutions have been administered to neutralize the stomach acid. For many Shigella vaccine trials, 100-120 ml of a bicarbonate solution is ingested followed by the live vaccine candidate, which is delivered in 30 ml of bicarbonate, water or saline. It is not clear if maximum bacterial viability is achieved under these conditions. Also, volumes of neutralizing buffer that are optimal for adults may be unsuitable for children and infants. To address these questions, we performed studies to determine the viability and stability of a Shigella sonnei vaccine candidate, WRSS1, in a mixture of different volumes of five different buffer solutions added to hydrochloric acid to simulate gastric acidity. Among the buffers tested, bicarbonate solution, rotavirus buffer and CeraVacx were better at neutralizing acid and maintaining the viability of WRSS1. Also, a much smaller volume of the neutralizing buffer was sufficient to counteract stomach acid while maintaining bacterial viability. Published by Elsevier Ltd.

Thermal stability of tagatose in solution.

PubMed

Luecke, Katherine J; Bell, Leonard N

2010-05-01

Tagatose, a monosaccharide similar to fructose, has been shown to behave as a prebiotic. To deliver this prebiotic benefit, tagatose must not degrade during the processing of foods and beverages. The objective of this study was to evaluate the thermal stability of tagatose in solutions. Tagatose solutions were prepared in 0.02 and 0.1 M phosphate and citrate buffers at pHs 3 and 7, which were then held at 60, 70, and 80 degrees C. Pseudo-1st-order rate constants for tagatose degradation were determined. In citrate and phosphate buffers at pH 3, minimal tagatose was lost and slight browning was observed. At pH 7, tagatose degradation rates were enhanced. Degradation was faster in phosphate buffer than citrate buffer. Higher buffer concentrations also increased the degradation rate constants. Enhanced browning accompanied tagatose degradation in all buffer solutions at pH 7. Using the activation energies for tagatose degradation, less than 0.5% and 0.02% tagatose would be lost under basic vat and HTST pasteurization conditions, respectively. Although tagatose does breakdown at elevated temperatures, the amount of tagatose lost during typical thermal processing conditions would be virtually negligible. Practical Application: Tagatose degradation occurs minimally during pasteurization, which may allow for its incorporation into beverages as a prebiotic.

THE KINETICS OF SAPONIFICATION OF IODOACETIC ACID BY SODIUM HYDROXIDE AND BY CERTAIN ALKALINE BUFFER SOLUTIONS.

PubMed

Brdicka, R

1936-07-20

1. The rate of the saponification of iodoacetic acid in sodium hydroxide and alkaline buffer solutions yielding glycollic acid was measured by means of Heyrovský's polarographic method. 2. From the bimolecular velocity constants, increasing with the ionic strength of the solution, the Brönsted factor, F, which characterizes the primary salt effect, was calculated. 3. In the borate buffer solutions the monomolecular constants of the saponification were determined which, at values above the pH of neutralization of boric acid, show a proportionality to the concentration of hydroxyl anions. Below the pH of neutralization of boric acid, they are proportional to the concentration of borate anions.

A water-processable organic electron-selective layer for solution-processed inverted organic solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Dongcheng; Zhou, Hu; Cai, Ping

2014-02-03

A triazine- and pyridinium-containing water-soluble material of 1,1′,1″-(4,4′,4″-(1,3,5-triazine-2,4,6-triyl)tris(benzene-4,1-diyl)) tris(methylene)tripyridinium bromide (TzPyBr) was developed as an organic electron-selective layer in solution-processed inverted organic solar cells due to its strong anti-erosion capacity against non-polar organic solvents commonly used for the active layer. Ohmic-like contact with the adjacent active materials like fullerene derivatives is speculated to be formed, as confirmed by the work-function measurements with scanning Kelvin probe and ultraviolet photoelectron spectroscopy techniques. Besides, considering the deep highest occupied molecular orbital energy level of TzPyBr, excellent hole-blocking property of the electron-selective layer is also anticipated. The inverted organic photovoltaic devices based on themore » TzPyBr/ITO (indium tin oxide) bilayer cathode exhibit dramatically enhanced performance compared to the control devices with bare ITO as the cathode and even higher efficiency than the conventional type devices with ITO and Al as the electrodes.« less

A label-free impedimetric DNA sensing chip integrated with AC electroosmotic stirring.

PubMed

Wu, Ching-Chou; Yang, Dong-Jie

2013-05-15

AC electroosmosis (ACEO) flow and label-free electrochemical impedance spectroscopy are employed to increase the hybridization rate and specifically detect target DNA (tDNA) concentrations. A low-ionic-strength solution, 6.1μS/cm 1mM Tris (pH 9.3), was used to produce ACEO and proved the feasibility of hybridization. Adequate voltage parameters for the simultaneous ACEO driving and DNA hybridization in the 1mM Tris solution were 1.5 Vpp and 200Hz. Moreover, an electrode set with a 1:4 ring width-to-disk diameter ratio exhibited a larger ACEO velocity above the disk electrode surface to improve collecting efficiency. The ACEO-integrated DNA sensing chips could reach 90% saturation hybridization within 117s. The linear range and detection limit of the sensors was 10aM-10pM and 10aM, respectively. The label-free impedimetric DNA sensing chips with integrated ACEO stirring can perform rapid hybridization and highly-sensitive detections to specifically measure tDNA concentrations. Copyright © 2013 Elsevier B.V. All rights reserved.

Crystal growth, structural, optical, spectral and thermal studies of tris( L-phenylalanine) L-phenylalaninium nitrate: A new organic nonlinear optical material

NASA Astrophysics Data System (ADS)

Prakash, M.; Geetha, D.; Lydia Caroline, M.

2011-10-01

Tris( L-phenylalanine) L-phenylalaninium nitrate, C 9H 12NO 2+·NO 3-·3C 9H 11NO 2 (TPLPN), a new organic nonlinear optical material was grown from aqueous solution by slow evaporation solution growth at room temperature. The grown crystals were subjected to powder X-ray diffraction and single crystal X-ray diffraction studies to confirm the crystalline nature and crystal structure. The modes of vibration of different molecular groups present in TPLPN have been identified by FTIR spectral analysis. The presence of hydrogen and carbon in the grown crystal were confirmed by using proton and carbon nuclear magnetic resonance (NMR) spectral analyses. The optical transmission spectral study establishes good transmitting ability of the crystal in the entire visible region. The thermogravimetric (TG) and differential thermal analyses (DTA) were carried out to understand the thermal stability of the sample. The nonlinear optical property of the compound observed using Kurtz powder second harmonic generation test assets the suitability of the grown material for the frequency conversion of laser radiation of Nd:YAG.

Acid neutralizing processes in an alpine watershed front range, Colorado, U.S.A.-1: Buffering capacity of dissolved organic carbon in soil solutions

USGS Publications Warehouse

Iggy, Litaor M.; Thurman, E.M.

1988-01-01

Soil interstitial waters in the Green Lakes Valley, Front Range, Colorado were studied to evaluate the capacity of the soil system to buffer acid deposition. In order to determine the contribution of humic substances to the buffering capacity of a given soil, dissolved organic carbon (DOC) and pH of the soil solutions were measured. The concentration of the organic anion, Ai-, derived from DOC at sample pH and the concentration of organic anion, Ax- at the equivalence point were calculated using carboxyl contents from isolated and purified humic material from soil solutions. Subtracting Ax- from Ai- yields the contribution of humic substances to the buffering capacity (Aequiv.-). Using this method, one can evaluate the relative contribution of inorganic and organic constituents to the acid neutralizing capacity (ANC) of the soil solutions. The relative contribution of organic acids to the overall ANC was found to be extremely important in the alpine wetland (52%) and the forest-tundra ecotone (40%), and somewhat less important in the alpine tundra sites (20%). A failure to recognize the importance of organic acids in soil solutions to the ANC will result in erroneous estimates of the buffering capacity in the alpine environment of the Front Range, Colorado. ?? 1988.

Anion responsive Europium (III) complexes for Optical Sensing and PARACEST MRI

NASA Astrophysics Data System (ADS)

Buttarazzi, Leandro Alfredo

The Eu(III) complexes of 1-(acetyl-7-Methyl-4-(trifluoromethyl) quinolin-2(1H)-one)4,7,10 tris(2-hydroxypropyl)-1,4,7,10-tetraazacycladodecane (Eu(S-THPC)3+ ) and 1-(acetyl-dioctadecylamine)4,7,10 tris(hydroxypropyl)-1,4,7,10-tetraazacycladodecane (Eu(S-THMC)3+) were studied in order to develop complexes that are both optical sensors and MRI contrast agents that respond to biologically relevant anions. Both complexes are related to Eu(S-THP) where S-THP = (1S,4S,7S,10S)-1,4,7,10-tetrakis(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane. Eu(III) excitation, emission and time resolved luminescence spectroscopy experiments were used to study binding of the anions. One complex, Eu(THPC)3+ has an appended carbostyril dye for sensitization of Eu(III) luminescence. Luminescence experiments were done on this complex in order to quantify the effectiveness of the energy transfer from the dye to the lanthanide and to obtain binding constants of the anions from the Eu(III) emission peaks. Emission spectra were obtained by exciting the chromophore at 340 nm. Our results suggest that phosphate binds with a dissociation constant (Kd) of 4.2mM and citrate binds with a Kd of 228 uM. The quantum yield for the complex was low compared to other reported complexes in literature. Eu(S-THMC) 3+, and Eu(S-THMAC)3+ containing long carbon chains for incorporation into liposomes were explored as an approach to develop complexes with increased sensitivity as CEST agents. CEST experiments with the complex incorporated into a liposome and as a micelle were carried out. Liposome formation was achieved but no CEST effect was observed with two different lanthanide complexes. Eu(S-THMC)3+ gave the most promising results by showing CEST in acetonitrile and 50/50 acetonitrile/H 2O. However further experiments with this complex in buffered aqueous solution failed. Yb(S-THMAC)3+ solubility was poor in both acetonitrile and in water and this likely prevented the observation of CEST spectra.

Low Molecular Weight Chitosan–Insulin Polyelectrolyte Complex: Characterization and Stability Studies

PubMed Central

Al-Kurdi, Zakieh I.; Chowdhry, Babur Z.; Leharne, Stephen A.; Al Omari, Mahmoud M. H.; Badwan, Adnan A.

2015-01-01

The aim of the work reported herein was to investigate the effect of various low molecular weight chitosans (LMWCs) on the stability of insulin using USP HPLC methods. Insulin was found to be stable in a polyelectrolyte complex (PEC) consisting of insulin and LMWC in the presence of a Tris-buffer at pH 6.5. In the presence of LMWC, the stability of insulin increased with decreasing molecular weight of LMWC; 13 kDa LMWC was the most efficient molecular weight for enhancing the physical and chemical stability of insulin. Solubilization of insulin-LMWC polyelectrolyte complex (I-LMWC PEC) in a reverse micelle (RM) system, administered to diabetic rats, results in an oral delivery system for insulin with acceptable bioactivity. PMID:25830681

Identification of succinimide sites in proteins by N-terminal sequence analysis after alkaline hydroxylamine cleavage.

PubMed Central

Kwong, M. Y.; Harris, R. J.

1994-01-01

Under favorable conditions, Asp or Asn residues can undergo rearrangement to a succinimide (cyclic imide), which may also serve as an intermediate for deamidation and/or isoaspartate formation. Direct identification of such succinimides by peptide mapping is hampered by their lability at neutral and alkaline pH. We determined that incubation in 2 M hydroxylamine, 0.2 M Tris buffer, pH 9, for 2 h at 45 degrees C will specifically cleave on the C-terminal side of succinimides without cleavage at Asn-Gly bonds; yields are typically approximately 50%. N-terminal sequence analysis can then be used to identify an internal sequence generated by cleavage of the succinimide, hence identifying the succinimide site. PMID:8142891

Resonance light scattering technique for the determination of protein with rutin and cetylpyridine bromide system.

PubMed

Liu, Yang; Yang, Jinghe; Liu, Shufang; Wu, Xia; Su, Benyu; Wu, Tao

2005-02-01

A new resonance light scattering (RLS) assay of protein is presented. In Tris-NaOH (pH = 10.93) buffer, the RLS of rutin-cetylpyridine bromide (CPB) system can be greatly enhanced by protein, including bovine serum albumin (BSA) and human serum albumin (HSA). The enhanced RLS intensities are in proportion to the concentration of proteins in the range of 5 x 10(-9) to 2.5 x 10(-6) g ml(-1) for BSA and 2.5 x 10(-8) to 3.5 x 10(-6) g ml(-1) for HSA. The detection limits (S/N = 3) are 3.0 ng ml(-1) for BSA and 10.0 ng ml(-1) for HSA. Samples are determined satisfactorily.

Anti-prelog reduction of prochiral carbonyl compounds by Oenococcus oeni in a biphasic system.

PubMed

Hu, Jian; Xu, Yan

2006-07-01

An aqueous-organic biphasic system was established and used with whole cells of Oenococcus oeni to reduce 2-octanone to (R)-2-octanol. The conversion reached 99% when the Tris/borate buffer was increased from 50 mM to 300 mM in the aqueous phase. In addition, the conversion increased as the log P value of the organic solvent changed from 0.5 to 6.6. Under optimized conditions, the conversion of (R)-2-octanol reached 99% from 0.5 M 2-octanone with an optical purity of 99% e.e. The biphasic system allows the anti-Prelog reduction of aliphatic and aromatic ketones to furnish (R)-configurated alcohols in high optical purity as well.

Topology and Function of Human P-Glycoprotein in Multidrug Resistant Breast Cancer Cells.

DTIC Science & Technology

1995-09-01

membrane orientation and insertion process co-translationally. For the C-terminal half of Pgp, little is known about the regulatory mechanisms of...solution (in mM: 250 sucrose, 10 Tris-HC1, pH 7.5, 150 NaCl) for further processing . For experiments requiring protease digestion and endoglycosidase...steps), 40 ms after the start of the voltage pulse . Bath and pipette solution compositions were as follows (in mM): NMDG-C1 pipette (280 mosmol/kg

Photoinduced oxidation of a water-soluble manganese(III) porphyrin

PubMed Central

Maliyackel, Anthony C.; Otvos, John W.; Spreer, Larry O.; Calvin, Melvin

1986-01-01

The photoinduced oxidation of tetra(N-methyl-4-pyridyl)porphyrinmanganese(III) has been achieved in homogeneous solution. The manganese porphyrin was used as an electron donor in a three-component system with tris-(2,2′-bipyridine)ruthenium(II) as the photosensitizer and chloropentaamminecobalt(III) as the electron acceptor. The photooxidized manganese porphyrin is unstable in aqueous solution, reverting to the starting manganese(III) porphyrin. The oxidation of manganese(III) porphyrin and the subsequent reduction of the oxidized porphyrin can be cycled repeatedly. PMID:16593699

Making pH Tangible.

ERIC Educational Resources Information Center

McIntosh, Elizabeth; Moss, Robert

1995-01-01

Presents a laboratory exercise in which students test the pH of different substances, study the effect of a buffer on acidic solutions by comparing the behavior of buffered and unbuffered solutions upon the addition of acid, and compare common over-the-counter antacid remedies. (MKR)

Next Generation Trusted Radiation Identification System (NG-TRIS).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flynn, Adam J.; Amai, Wendy A.; Merkle, Peter Benedict

2010-05-01

The original Trusted Radiation Identification System (TRIS) was developed from 1999-2001, featuring information barrier technology to collect gamma radiation template measurements useful for arms control regime operations. The first TRIS design relied upon a multichannel analyzer (MCA) that was external to the protected volume of the system enclosure, undesirable from a system security perspective. An internal complex programmable logic device (CPLD) contained data which was not subject to software authentication. Physical authentication of the TRIS instrument case was performed by a sensitive but slow eddy-current inspection method. This paper describes progress to date for the Next Generation TRIS (NG-TRIS), whichmore » improves the TRIS design. We have incorporated the MCA internal to the trusted system volume, achieved full authentication of CPLD data, and have devised rapid methods to authenticate the system enclosure and weld seals of the NG-TRIS enclosure. For a complete discussion of the TRIS system and components upon which NG-TRIS is based, the reader is directed to the comprehensive user's manual and system reference of Seager, et al.« less

Assembly of Modified Ferritin Proteins on Carbon Nanotubes and its Electrocatalytic Activity for Oxygen Reduction

NASA Technical Reports Server (NTRS)

Kim, Jae-Woo; Lillehei, Peter T.; Park, Cheol

2012-01-01

Highly effective dispersions of carbon nanotubes (CNTs) can be made using a commercially available buffer solution. Buffer solutions of 3-(N-morpholino)-propanesulfonic acid (MOPS), which consists of a cyclic ring with nitrogen and oxygen heteroatoms, a charged group, and an alkyl chain greatly enhance the dispersibility and stability of CNTs in aqueous solutions. Additionally, the ability of biomolecules, especially cationized Pt-cored ferritins, to adhere onto the well-dispersed CNTs in the aqueous buffer solution is also improved. This was accomplished without the use of surfactant molecules, which are detrimental to the electrical, mechanical, and other physical properties of the resulting products. The assembled Pt-cored ferritin proteins on the CNTs were used as an electrocatalyst for oxygen reduction

THE KINETICS OF SAPONIFICATION OF IODOACETIC ACID BY SODIUM HYDROXIDE AND BY CERTAIN ALKALINE BUFFER SOLUTIONS

PubMed Central

Brdička, R.

1936-01-01

1. The rate of the saponification of iodoacetic acid in sodium hydroxide and alkaline buffer solutions yielding glycollic acid was measured by means of Heyrovský's polarographic method. 2. From the bimolecular velocity constants, increasing with the ionic strength of the solution, the Brönsted factor, F, which characterizes the primary salt effect, was calculated. 3. In the borate buffer solutions the monomolecular constants of the saponification were determined which, at values above the pH of neutralization of boric acid, show a proportionality to the concentration of hydroxyl anions. Below the pH of neutralization of boric acid, they are proportional to the concentration of borate anions. PMID:19872968

A highly Selective Fluorescent Sensor for Monitoring Cu2+ Ion: Synthesis, Characterization and Photophysical Properties.

PubMed

Aderinto, Stephen Opeyemi; Xu, Yuling; Peng, Hongping; Wang, Fei; Wu, Huilu; Fan, Xuyang

2017-01-01

A new fluorescent sensor, 4-allylamine-N-(N-salicylidene)-1,8-naphthalimide (1), anchoring a naphthalimide moiety as fluorophore and a Schiff base group as receptor, was synthesized and characterized. The photophysical properties of sensor 1 were conducted in organic solvents of different polarities. Our study revealed that, depending on the solvent polarity, the fluorescence quantum yields varied from 0.59 to 0.89. The fluorescent activity of the sensor was monitored and the sensor was consequently applied for the detection of Cu 2+ with high selectivity over various metal ions by fluorescence quenching in Tris-HCl (pH = 7.2) buffer/DMF (1:1, v/v) solution. From the binding stoichiometry, it was indicated that a 1:1 complex was formed between Cu 2+ and the sensor 1. The fluorescence intensity was linear with Cu 2+ in the concentration range 0.5-5 μM. Moreso, the detection limit was calculated to be 0.32 μM, which is sufficiently low for good sensitivity of Cu 2+ ion. The binding mode was due to the intramolecular charge transfer (ICT) and the coordination of Cu 2+ with C = N and hydroxyl oxygen groups of the sensor 1. The sensor proved effective for Cu 2+ monitoring in real water samples with recovery rates of 95-112.6 % obtained.

3D printing of Mg-substituted wollastonite reinforcing diopside porous bioceramics with enhanced mechanical and biological performances.

PubMed

He, Dongshuang; Zhuang, Chen; Xu, Sanzhong; Ke, Xiurong; Yang, Xianyan; Zhang, Lei; Yang, Guojing; Chen, Xiaoyi; Mou, Xiaozhou; Liu, An; Gou, Zhongru

2016-09-01

Mechanical strength and its long-term stability of bioceramic scaffolds is still a problem to treat the osteonecrosis of the femoral head. Considering the long-term stability of diopside (DIO) ceramic but poor mechanical strength, we developed the DIO-based porous bioceramic composites via dilute magnesium substituted wollastonite reinforcing and three-dimensional (3D) printing. The experimental results showed that the secondary phase (i.e. 10% magnesium substituting calcium silicate; CSM10) could readily improve the sintering property of the bioceramic composites (DIO/CSM10- x , x  = 0-30) with increasing the CSM10 content from 0% to 30%, and the presence of the CSM10 also improved the biomimetic apatite mineralization ability in the pore struts of the scaffolds. Furthermore, the flexible strength (12.5-30 MPa) and compressive strength (14-37 MPa) of the 3D printed porous bioceramics remarkably increased with increasing CSM10 content, and the compressive strength of DIO/CSM10-30 showed a limited decay (from 37 MPa to 29 MPa) in the Tris buffer solution for a long time stage (8 weeks). These findings suggest that the new CSM10-reinforced diopside porous constructs possess excellent mechanical properties and can potentially be used to the clinic, especially for the treatment of osteonecrosis of the femoral head work as a bioceramic rod.

Infectivity of RNA from inactivated poliovirus.

PubMed

Nuanualsuwan, Suphachai; Cliver, Dean O

2003-03-01

During inactivation of poliovirus type 1 (PV-1) by exposure to UV, hypochlorite, and heat (72 degrees C), the infectivity of the virus was compared with that of its RNA. DEAE-dextran (1-mg/ml concentration in Dulbecco's modified Eagle medium buffered with 0.05 M Tris, pH 7.4) was used to facilitate transfecting PV-1 RNA into FRhK-4 host cells. After interaction of PV-1 RNA with cell monolayer at room temperature (21 to 22 degrees C) for 20 min, the monolayers were washed with 5 ml of Hanks balanced salt solution. The remainder of the procedure was the same as that for the conventional plaque technique, which was also used for quantifying the PV-1 whole-particle infectivity. Plaque formation by extracted RNA was approximately 100,000-fold less efficient than that by whole virions. The slopes of best-fit regression lines of inactivation curves for virion infectivity and RNA infectivity were compared to determine the target of inactivation. For UV and hypochlorite inactivation the slopes of inactivation curves of virion infectivity and RNA infectivity were not statistically different. However, the difference of slopes of inactivation curves of virion infectivity and RNA infectivity was statistically significant for thermal inactivation. The results of these experiments indicate that viral RNA is a primary target of UV and hypochlorite inactivations but that the sole target of thermal inactivation is the viral capsid.

Infectivity of RNA from Inactivated Poliovirus

PubMed Central

Nuanualsuwan, Suphachai; Cliver, Dean O.

2003-01-01

During inactivation of poliovirus type 1 (PV-1) by exposure to UV, hypochlorite, and heat (72°C), the infectivity of the virus was compared with that of its RNA. DEAE-dextran (1-mg/ml concentration in Dulbecco's modified Eagle medium buffered with 0.05 M Tris, pH 7.4) was used to facilitate transfecting PV-1 RNA into FRhK-4 host cells. After interaction of PV-1 RNA with cell monolayer at room temperature (21 to 22°C) for 20 min, the monolayers were washed with 5 ml of Hanks balanced salt solution. The remainder of the procedure was the same as that for the conventional plaque technique, which was also used for quantifying the PV-1 whole-particle infectivity. Plaque formation by extracted RNA was approximately 100,000-fold less efficient than that by whole virions. The slopes of best-fit regression lines of inactivation curves for virion infectivity and RNA infectivity were compared to determine the target of inactivation. For UV and hypochlorite inactivation the slopes of inactivation curves of virion infectivity and RNA infectivity were not statistically different. However, the difference of slopes of inactivation curves of virion infectivity and RNA infectivity was statistically significant for thermal inactivation. The results of these experiments indicate that viral RNA is a primary target of UV and hypochlorite inactivations but that the sole target of thermal inactivation is the viral capsid. PMID:12620852

Molecular spectroscopic studies on the interaction of ferulic acid with calf thymus DNA

NASA Astrophysics Data System (ADS)

Zhang, Shufang; Sun, Xuejun; Qu, Fengli; Kong, Rongmei

2013-08-01

The interaction between ferulic acid and calf thymus deoxyribonucleic acid (ctDNA) under physiological conditions (Tris-HCl buffer solutions, pH 7.4) was investigated by UV-Vis spectroscopy, fluorescence spectroscopy, DNA melting techniques, and viscosity measurements. Results indicated that a complex of ferulic acid with ctDNA was formed with a binding constant of K290K = 7.60 × 104 L mol-1 and K310K = 4.90 × 104 L mol-1. The thermodynamic parameters enthalpy change (ΔH°), entropy change (ΔS°) and Gibbs free energy (ΔG°) were calculated to be -1.69 × 104 J mol-1, 35.36 J K-1 mol-1 and -2.79 × 104 J mol-1 at 310 K, respectively. The acting forces between ferulic acid and DNA mainly included hydrophobic interaction and hydrogen bonds. Acridine orange displacement studies revealed that ferulic acid can substitute for AO probe in the AO-DNA complex which was indicative of intercalation binding. Thermal denaturation study suggested that the interaction of ferulic acid with DNA could result in the increase of the denaturation temperature, which indicated that the stabilization of the DNA helix was increased in the presence of ferulic acid. Spectroscopic techniques together with melting techniques and viscosity determination provided evidences of intercalation mode of binding for the interaction between ferulic acid and ctDNA.

Preparation of Cotton-Wool-Like Poly(lactic acid)-Based Composites Consisting of Core-Shell-Type Fibers

PubMed Central

Wang, Jian; Zhou, Pin; Obata, Akiko; Jones, Julian R.; Kasuga, Toshihiro

2015-01-01

In previous works, we reported the fabrication of cotton-wool-like composites consisting of siloxane-doped vaterite and poly(l-lactic acid) (SiVPCs). Various irregularly shaped bone voids can be filled with the composite, which effectively supplies calcium and silicate ions, enhancing the bone formation by stimulating the cells. The composites, however, were brittle and showed an initial burst release of ions. In the present work, to improve the mechanical flexibility and ion release, the composite fiber was coated with a soft, thin layer consisting of poly(d,l-lactic-co-glycolic acid) (PLGA). A coaxial electrospinning technique was used to prepare a cotton-wool-like material comprising “core-shell”-type fibers with a diameter of ~12 µm. The fibers, which consisted of SiVPC coated with a ~2-µm-thick PLGA layer, were mechanically flexible; even under a uniaxial compressive load of 1.5 kPa, the cotton-wool-like material did not exhibit fracture of the fibers and, after removing the load, showed a ~60% recovery. In Tris buffer solution, the initial burst release of calcium and silicate ions from the “core-shell”-type fibers was effectively controlled, and the ions were slowly released after one day. Thus, the mechanical flexibility and ion-release behavior of the composites were drastically improved by the thin PLGA coating. PMID:28793691

Novel adsorbent for DNA adsorption: Fe(3+)-attached sporopollenin particles embedded composite cryogels.

PubMed

Ceylan, Şeyda; Odabaşı, Mehmet

2013-12-01

The aim of this study is to prepare supermacroporous cryogels embedded with Fe(3+)-attached sporopollenin particles (Fe(3++)-ASPs) having large surface area for high DNA adsorption capacity. Supermacroporous poly(2-hydroxyethyl methacrylate) (PHEMA)-based monolithic cryogel column embedded with Fe3+(+)-ASPs was prepared by radical cryo-copolymerization of 2-hydroxyethyl methacrylate (HEMA) with N,N´-methylene- bis-acrylamide (MBAAm) as cross-linker directly in a plastic syringe for DNA adsorption studies. Firstly, Fe3+(+) ions were attached to the sporopollenin particles (SPs), then the supermacroporous PHEMA cryogel with embedded Fe(3++)-ASPs was produced by free radical polymerization using N,N,N´, N´-Tetramethylethylenediamine (TEMED) and ammonium persulfate (APS) as initiator/activator pair in an ice bath. Optimum conditions of adsorption experiments were performed at pH 6.0 (0.02 M Tris buffer containing 0.2 M NaCl), with flow rate of 0.5 mL/min, and at 5°C. The maximum amount of DNA adsorption from aqueous solution was very high (109 mg/g SPs) with initial concentration of 3 mg/mL. It was observed that DNA could be repeatedly adsorbed and desorbed with this composite cryogel without significant loss of adsorption capacity. As a result, higher amounts of DNA adsorbed these composite cryogels are expected to be good candidate for achieving higher removal of anti-DNA antibodies from systemic lupus erythematosus (SLE) patients plasma.

Aqueous solution dispersement of carbon nanotubes

NASA Technical Reports Server (NTRS)

Kim, Jae-Woo (Inventor); Park, Cheol (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)

2011-01-01

Carbon nanotubes (CNTs) are dispersed in an aqueous buffer solution consisting of at least 50 weight percent water and a remainder weight percent that includes a buffer material. The buffer material has a molecular structure defined by a first end, a second end, and a middle disposed between the first and second ends. The first end is a cyclic ring with nitrogen and oxygen heteroatomes, the middle is a hydrophobic alkyl chain, and the second end is a charged group.

A two-step dilution tris-egg yolk extender containing Equex STM significantly improves sperm cryopreservation in the African wild dog (Lycaon pictus).

PubMed

Van den Berghe, Femke; Paris, Monique Christina Johanna; Briggs, Michael Brent; Farstad, Wenche Kristin; Paris, Damien Boyd Bertrand Paul

2018-02-01

Conservation management of endangered African wild dogs (AWD; Lycaon pictus) can benefit greatly from development of sperm freezing and artificial insemination. Previous freezing attempts yielded nearly 0% motile sperm within 2 h of thawing. In this study, two canine freezing protocols were tested: Protocol 1: a one-step dilution in TRIS-20% egg yolk containing 8% glycerol; and Protocol 2: a two-step dilution in TRIS-20% egg yolk containing a final extender concentration of 5% glycerol and 0.5% Equex STM, coupled with a TRIS-citrate-fructose thawing solution. Semen was collected by electroejaculation from n = 24 AWDs, of which eight ejaculates of sufficient quality (four good quality with initial sperm motility of 75.0 ± 4.4% and four poor quality; showing rapid decrease in sperm motility to 3.3 ± 3.3% prior to freezing) were frozen. For good quality samples, motility and sperm motility index persisted for up to 8 h for Protocol 2, and was higher between 2 and 6 h after thawing with a decrease from 4 h of incubation. Motility dropped to nearly 0% after 2 h incubation for Protocol 1. Viability was higher for Protocol 2 throughout the 8 h of incubation, with a decrease after 6 h, compared to 4 h for Protocol 1. Acrosome integrity was higher for Protocol 2 throughout post-thaw incubation, with a decrease after 2 h for both protocols. Protocols did not differ in normal sperm morphology or DNA integrity. Poor quality samples yielded similar results, except for acrosome integrity, which declined for Protocol 2. In conclusion, a two-step dilution in TRIS-egg yolk-glycerol extender containing Equex STM yields significantly improved post-thaw quality and longevity of AWD spermatozoa, making it suitable for sperm banking and artificial insemination initiatives. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Single-channel measurements of an N-acetylneuraminic acid-inducible outer membrane channel in Escherichia coli

PubMed Central

Giri, Janhavi; Tang, John M.; Wirth, Christophe; Peneff, Caroline M.

2012-01-01

NanC is an Escherichia coli outer membrane protein involved in sialic acid (Neu5Ac, i.e., N-acetylneuraminic acid) uptake. Expression of the NanC gene is induced and controlled by Neu5Ac. The transport mechanism of Neu5Ac is not known. The structure of NanC was recently solved (PDB code: 2WJQ) and includes a unique arrangement of positively charged (basic) side chains consistent with a role in acidic sugar transport. However, initial functional measurements of NanC failed to find its role in the transport of sialic acids, perhaps because of the ionic conditions used in the experiments. We show here that the ionic conditions generally preferred for measuring the function of outer-membrane porins are not appropriate for NanC. Single channels of NanC at pH 7.0 have: (1) conductance 100 pS to 800 pS in 100 mM KCl to 3 M KCl), (2) anion over cation selectivity (Vreversal = +16 mV in 250 mM KCl || 1 M KCl), and (3) two forms of voltage-dependent gating (channel closures above ±200 mV). Single-channel conductance decreases by 50% when HEPES concentration is increased from 100 μM to 100 mM in 250 mM KCl at pH 7.4, consistent with the two HEPES binding sites observed in the crystal structure. Studying alternative buffers, we find that phosphate interferes with the channel conductance. Single-channel conductance decreases by 19% when phosphate concentration is increased from 0 mM to 5 mM in 250 mM KCl at pH 8.0. Surprisingly, TRIS in the baths reacts with Ag|AgCl electrodes, producing artifacts even when the electrodes are on the far side of agar–KCl bridges. A suitable baseline solution for NanC is 250 mM KCl adjusted to pH 7.0 without buffer. PMID:22246445

Investigation of passive films formed on the surface of alloy 690 in borate buffer solution

NASA Astrophysics Data System (ADS)

Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Wenli, Guo

2015-10-01

The passive film formed on the surface of the alloy 690 in borate buffer solution was studied by potentiodynamic curves and electrochemical impedance spectroscopy. With the increasing of the passivation potential, the corrosion resistance of the alloy 690 reduced. Moreover, the corrosion resistance of the passive film was the lowest in the vicinity of 0.6 VSCE. These results were supported by XPS and Mott-Schottky analyses. The corrosion resistance of the alloy 690 increased with the increasing of passivated potential in borate buffer solution with chloride ion. The chloride ion decreased corrosion resistance of the alloy 690 according to point defect model.

Well-defined critical association concentration and rapid adsorption at the air/water interface of a short amphiphilic polymer, amphipol A8-35: a study by Förster resonance energy transfer and dynamic surface tension measurements.

PubMed

Giusti, Fabrice; Popot, Jean-Luc; Tribet, Christophe

2012-07-17

Amphipols (APols) are short amphiphilic polymers designed to handle membrane proteins (MPs) in aqueous solutions as an alternative to small surfactants (detergents). APols adsorb onto the transmembrane, hydrophobic surface of MPs, forming small, water-soluble complexes, in which the protein is biochemically stabilized. At variance with MP/detergent complexes, MP/APol ones remain stable even at extreme dilutions. Pure APol solutions self-associate into well-defined micelle-like globules comprising a few APol molecules, a rather unusual behavior for amphiphilic polymers, which typically form ill-defined assemblies. The best characterized APol to date, A8-35, is a random copolymer of acrylic acid, isopropylacrylamide, and octylacrylamide. In the present work, the concentration threshold for self-association of A8-35 in salty buffer (NaCl 100 mM, Tris/HCl 20 mM, pH 8.0) has been studied by Förster resonance energy transfer (FRET) measurements and tensiometry. In a 1:1 mol/mol mixture of APols grafted with either rhodamine or 7-nitro-1,2,3-benzoxadiazole, the FRET signal as a function of A8-35 concentration is essentially zero below a threshold concentration of 0.002 g·L(-1) and increases linearly with concentration above this threshold. This indicates that assembly takes place in a narrow concentration interval around 0.002 g·L(-1). Surface tension measurements decreases regularly with concentration until a threshold of ca. 0.004 g·L(-1), beyond which it reaches a plateau at ca. 30 mN·m(-1). Within experimental uncertainties, the two techniques thus yield a comparable estimate of the critical self-assembly concentration. The kinetics of variation of the surface tension was analyzed by dynamic surface tension measurements in the time window 10 ms-100 s. The rate of surface tension decrease was similar in solutions of A8-35 and of the anionic surfactant sodium dodecylsulfate when both compounds were at a similar molar concentration of n-alkyl moieties. Overall, the solution properties of APol "micelles" (in salty buffer) appear surprisingly similar to those of the micelles formed by small, nonpolymeric surfactants, a feature that was not anticipated owing to the polymeric and polydisperse nature of A8-35. The key to the remarkable stability to dilution of A8-35 globules, likely to include also that of MP/APol complexes, lies accordingly in the low value of the critical self-association concentration as compared to that of small amphiphilic analogues.

Electron transfer triggered by optical excitation of phenothiazine-tris(meta-phenylene-ethynylene)-(tricarbonyl)(bpy)(py)rhenium(I).

PubMed

Bingöl, Bahar; Durrell, Alec C; Keller, Gretchen E; Palmer, Joshua H; Grubbs, Robert H; Gray, Harry B

2013-04-25

We have investigated excited-state electron transfer in a donor-bridge-acceptor complex containing phenothiazine (PTZ) linked via tris(meta-phenylene-ethynylene) to a tricarbonyl(bipyridine)(pyridine)Re(I) unit. Time-resolved luminescence experiments reveal two excited-state (*Re) decay regimes, a multiexponential component with a mean lifetime of 2.7 ns and a longer monoexponential component of 530 ns in dichloromethane solution. The faster decay is attributed to PTZ → *Re electron transfer in a C-shaped PTZ-bridge-Re conformer (PTZ-Re ≈ 7.5 Å). We assign the longer lifetime, which is virtually identical to that of free *Re, to an extended conformer (PTZ-Re > 20 Å). The observed biexponential *Re decay requires that interconversion of PTZ-bridge-Re conformers be slower than 10(6) s(-1).

Expression and solubilization of insect cell-based rabies virus glycoprotein and assessment of its immunogenicity and protective efficacy in mice.

PubMed

Ramya, R; Mohana Subramanian, B; Sivakumar, V; Senthilkumar, R L; Sambasiva Rao, K R S; Srinivasan, V A

2011-10-01

Rabies is a fatal zoonotic disease of serious public health and economic significance worldwide. The rabies virus glycoprotein (RVG) has been the major target for subunit vaccine development, since it harbors domains responsible for induction of virus-neutralizing antibodies, infectivity, and neurovirulence. The glycoprotein (G) was cloned using the baculovirus expression vector system (BEVS) and expressed in Spodoptera frugiperda (Sf-9) cells. In order to obtain a soluble form of G suitable for experimentation in mice, 18 different combinations of buffers and detergents were evaluated for their ability to solubilize the insect cell membrane-associated G. The combination that involved 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS) detergent in lysis buffer 1, formulated with Tris, NaCl, 10% dimethyl sulfoxide (DMSO), and EDTA, gave the highest yield of soluble G, as evidenced by the experimental data. Subsequently, several other parameters, such as the concentration of CHAPS and the duration and temperature of the treatment for the effective solubilization of G, were optimized. The CHAPS detergent, buffered at a concentration of 0.4% to 0.7% (wt/vol) at room temperature (23 to 25°C) for 30 min to 1 h using buffer 1, containing 10% DMSO, resulted in consistently high yields. The G solubilized using CHAPS detergent was found to be immunogenic when tested in mice, as evidenced by high virus-neutralizing antibody titers in sera and 100% protection upon virulent intracerebral challenge with the challenge virus standard (CVS) strain of rabies virus. The results of the mice study indicated that G solubilized with CHAPS detergent retained the immunologically relevant domains in the native conformation, thereby paving the way for producing a cell-free and efficacious subunit vaccine.

Complement, Kinins, and Hereditary Angioedema: Mechanisms of Plasma Instability when C1 Inhibitor is Absent.

PubMed

Kaplan, Allen P; Joseph, Kusumam

2016-10-01

Plasma of patients with types I and II hereditary angioedema is unstable if incubated in a plastic (i.e., inert) vessel at 37 °C manifested by progressively increasing formation of bradykinin. There is also a persistent low level of C4 in 95 % of patients even when they are symptomatic. These phenomena are due to the properties of the C1r subcomponent of C1, factor XII, and the bimolecular complex of prekallikrein with high molecular weight kininogen (HK). Purified C1r auto-activates in physiologic buffers, activates C1s, which in turn depletes C4. This occurs when C1 inhibitor is deficient. The complex of prekallikrein-HK acquires an inducible active site not present in prekallikrein which in Tris-type buffers cleaves HK stoichiometrically to release bradykinin, or in phosphate buffer auto-activates to generate kallikrein and bradykinin. Thus immunologic depletion of C1 inhibitor from factor XII-deficient plasma (phosphate is the natural buffer) auto-activates on incubation to release bradykinin. Normal C1 inhibitor prevents this from occurring. During attacks of angioedema, if factor XII auto-activates on surfaces, the initial factor XIIa formed converts prekallikrein to kallikrein, and kallikrein cleaves HK to release bradykinin. Kallikrein also rapidly activates most remaining factor XII to factor XIIa. Additional cleavages convert factor XIIa to factor XIIf and factor XIIf activates C1r enzymatically so that C4 levels approach zero, and C2 is depleted. There is also a possibility that kallikrein is generated first as a result of activation of the prekallikrein-HK complex by heat shock protein 90 released from endothelial cells, followed by kallikrein activation of factor XII.

EQUALIZING THE ELECTRIC FIELD INTENSITY WITHIN CHICK BRAIN IMMERSED IN BUFFER SOLUTION AT DIFFERENT CARRIER FREQUENCIES

EPA Science Inventory

Presented here are the numerical relationships between incident power densities that produce the same average electric field intensity within a chick brain half immersed in buffered saline solution and exposed to a uniform electromagnetic field at carrier frequencies of 50, 147, ...

Differential effect of buffering agents on the crystallization of gemcitabine hydrochloride in frozen solutions.

PubMed

Patel, Mehulkumar; Munjal, Bhushan; Bansal, Arvind K

2014-08-25

The purpose of this study was to evaluate the differential effect of buffering agents on the crystallization of gemcitabine hydrochloride (GHCl) in frozen solutions. Four buffering agents, viz. citric acid (CA), malic acid (MA), succinic acid (SA) and tartaric acid (TA) were selected and their effect on GHCl crystallization was monitored using standard DSC and low temperature XRD. Onset of GHCl crystallization during heating run in DSC was measured to compare the differential effect of buffering agents. Glass transition temperature (Tg'), unfrozen water content in the freeze concentrate and crystallization propensity of the buffering agents was also determined for mechanistic understanding of the underlying effects. CA and MA inhibited while SA facilitated crystallization of GHCl even at 25 mM concentration. Increasing the concentration enhanced their effect. However, TA inhibited GHCl crystallization at concentrations <100mM and facilitated it at concentrations ≥100 mM. Lyophilization of GHCl with either SA or TA yielded elegant cakes, while CA and MA caused collapse. Tg' failed to explain the inhibitory effects of CA, MA and TA as all buffering agents lowered the Tg' of the system. Differential effect of buffering agents on GHCl crystallization could be explained by consideration of two opposing factors: (i) their own crystallization tendency and (ii) unfrozen water content in the freeze concentrate. In conclusion, it was established that API crystallization in frozen solution is affected by the type and concentration of the buffering agents. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of morphological response of red cells in a sucrose solution.

PubMed

Rudenko, Sergey V

2009-01-01

The dynamics of red cell shape changes following transfer into sucrose media having a low chloride content was studied. Based on a large number of measurements, six types of morphological response (MR), differing both in the degree of shape changes and the time course of the process, were identified. The most prominent type of response is a triphasic sequence of shape changes consisting of a fast transformation into a sphere (phase 1), followed by restoration of the discoid shape (phase 2) and final transformation into spherostomatocytes (phase 3), with individual parameters which could vary significantly. It was found that individual morphological response exhibited day to day variations, depending on the initial state of the red blood cells and the donor, but to a larger extent depended on the composition of the sucrose solution, such as concentration and type of buffers, the presence of EDTA, calcium, as well as very small amounts of extracellular hemoglobin. MR shows strong pH and ionic strength dependence. Low pH inhibited phase 1 and high pH changed dramatically the time course of the response. Increasing ionic strength inhibited all phases of MR, and at concentrations above 10-20 mM NaCl it was fully suppressed. Tris and phosphate were also inhibitory whereas HEPES, MOPS and Tricine were less effective. MR occurred also in hypertonic or hypotonic sucrose solutions, with exception of extreme hypotonicity due to volume restrictions. It is concluded that strong membrane depolarization per se is not a causal factor leading to MR, and its different phases could be regulated independently. For some types of morphological response the fast shape transformation from sphere to disc and back to sphere occurs within a 10 s time interval and could be accelerated several fold in the presence of a small amount of hemoglobin. It is suggested that MR represents a type of general cell reaction that occurs upon exposure to low ionic strength.

Analytical and semi-preparative enantioresolution of (RS)-ketorolac from pharmaceutical formulation and in human plasma by HPLC.

PubMed

Lal, Manohar; Bhushan, Ravi

2016-10-01

An efficient, simple, validated, analytical and semi-preparative HPLC method has been developed for direct enantioresolution of (RS)-Ketorolac (Ket) using monochloro-methylated derivatives of cellulose and amylose, i.e. cellulose (tris-3-chloro-4-methylphenylcarbamate) and amylose (tris-5-chloro-2-methylphenylcarbamate) as chiral stationary phases (CSPs) with photo diode array detection at 320 nm. Enantioresolution was carried out in samples of human plasma spiked with (RS)-Ket under normal and reversed-phase elution modes with suitable mobile phase compositions. The effect of nature of alcohols (MeOH, EtOH, PrOH and n-BuOH) and other solvents (MeCN and MeOH) as organic modifiers in the mobile phase was investigated on the separation performance of two CSPs in terms of retention and separation of enantiomers. The best resolution was observed on cellulose-based CSP using EtOH, while using 2-PrOH (15%) and amylose-based CSP obtained the highest retention. Under reversed-phase elution mode the best enantioseparation was observed using 30% MeCN with ammonium formate buffer. The elution order of enantiomers was ascertained by determining specific rotations. The limit of detection and quantitation values were 5 and 15.5 ng/mL for each enantiomer of (RS)-Ket, respectively. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Electrochemical preparation of tris(tert-butyldimethylsilyl)cyclopropene and its hydride abstraction to tris(tert-butyldimethylsilyl)cyclopropenium tetrafluoroborate

PubMed Central

Buchholz, Herwig A.; Prakash, G. K. Surya; Deffieux, Denis; Olah, George A.

1999-01-01

Electrochemical reductive tert-butyldimethylsilylation of tetrachlorocyclopropene to 1,2,3-tris(tert-butyldimethylsilyl)cyclopropene, a potential strained precursor for Diels–Alder and related cycloaddition reactions, is described. By hydride abstraction with nitrosonium tetrafluoroborate, 1,2,3-tris(tert-butyldimethylsilyl)cyclopropene is ionized quantitatively to Hückeloid 2π aromatic tris(tert-butyldimethylsilyl)cyclopropenium tetrafluoroborate. PMID:10468551

Biogeochemistry of the sulfur oxidizer Thiomicrospira thermophila

NASA Astrophysics Data System (ADS)

Houghton, J.; Fike, D. A.; Wills, E.; Foustoukos, D.

2013-12-01

Near-seafloor hydrothermal environments such as diffuse flow venting or subsurface mixing are characterized by rapidly changing conditions and steep chemical and thermal gradients. Microorganisms living in these environments can take advantage of these changes by switching among metabolic pathways rather than specializing. We present reaction stoichiometry and rates for T. thermophila grown in a closed system both at ambient and elevated pressure (50 bars) that demonstrate substantial metabolic flexibility, shifting between up to 5 different sulfur cycling reactions over a 24 hour period. Based on the stoichiometry between S2O3 consumed and SO4 produced, three reactions are sulfur oxidation and two are disproportionation, which has not previously been demonstrated for Thiomicrospira strains. Reactants include S2O3, elemental S (both polymeric S chains and S8 rings), HS-, and O2, while products include polymeric elemental S, SO4, HS-, and polysulfides. The presence of μmolal concentrations of HS- has been confirmed during the time series only when stoichiometry predicts disproportionation. Production of HS- in the presence of elemental S results in abiotic conversion to polysulfides, keeping the sulfide concentrations low in solution. The transition from oxidation to disproportionation appears to be triggered by a depletion in dissolved oxygen and the rate of reaction is a second order function of S2O3 and O2 concentrations. Growth was tested at conditions spanning their pH tolerance (5.0 - 8.0) using a citrate buffer (pH 5.0), unbuffered media (initial pH 7.0), and Tris buffer (pH 8.0). The highest rates are observed at pH 8.0 with rates decreasing as a function of pH. The lowest rate occurs at pH 5.0 and exhibits pseudo-first order behavior over a 24 hour period, likely due to a long lag and very slow growth. Repeat injections after the culture is acclimated to the experimental conditions result in very high pseudo-first order rates due to rapid consumption of all available thiosulfate prior to oxygen depletion. Results from high-pressure closed system experiments (at 50 bars, buffered at pH 5.0) exhibit comparable rates to the corresponding ambient pressure condition. Future work will address the effect of dissolved O2 on sulfur disproportionation using continuous culturing of T. thermophila at deep-sea pressure conditions (>200 bar).

Identification of a Novel Esterase from Marine Environmental Genomic DNA Libraries and Its Application in Production of Free All- trans-Astaxanthin.

PubMed

Lu, Ping; Gao, Xinwei; Dong, Hao; Liu, Zhen; Secundo, Francesco; Xue, Changhu; Mao, Xiangzhao

2018-03-21

Astaxanthin is a pigment with various functions. Free astaxanthin is obtained mainly through saponification methods, which could result in many byproducts. Enzymatic methods using lipases have been used in a few cases, while there are no reports on the use of esterases for the production of free astaxanthin. Herein we present the screening and identification of a novel esterase (Est3-14) from a marine mud metagenomic library. Est3-14 is pH-sensitive and keeps good stability in alkaline buffers (residual activity 94%, pH 8.0, 4 °C, and 36 h). Meanwhile, Est3-14 keeps a good stability in the medium temperature condition (residual activity 56.7%, pH 8.0, 40 °C, and 84 h). Est3-14 displayed high hydrolysis activity to prepare free all- trans-astaxanthin in biphasic systems. Furthermore, under optimal conditions (0.5 mL ethanol, 6 mL 0.1 M Tris-HCl buffer, pH 8.0, 0.5% (w/v) H. pluvialis oil, 40 °C), the hydrolytic conversion ratio was 99.3% after 36 h.

Fluorescence lifetime imaging of oxygen in dental biofilm

NASA Astrophysics Data System (ADS)

Gerritsen, Hans C.; de Grauw, Cees J.

2000-12-01

Dental biofilm consists of micro-colonies of bacteria embedded in a matrix of polysaccharides and salivary proteins. pH and oxygen concentration are of great importance in dental biofilm. Both can be measured using fluorescence techniques. The imaging of dental biofilm is complicated by the thickness of the biofilms that can be up to several hundred micrometers thick. Here, we employed a combination of two-photon excitation microscopy with fluorescence lifetime imaging to quantify the oxygen concentration in dental biofilm. Collisional quenching of fluorescent probes by molecular oxygen leads to a reduction of the fluorescence lifetime of the probe. We employed this mechanism to measure the oxygen concentration distribution in dental biofilm by means of fluorescence lifetime imaging. Here, TRIS Ruthenium chloride hydrate was used as an oxygen probe. A calibration procedure on buffers was use to measure the lifetime response of this Ruthenium probe. The results are in agreement with the Stern-Volmer equation. A linear relation was found between the ratio of the unquenched and the quenched lifetime and the oxygen concentration. The biofilm fluorescence lifetime imaging results show a strong oxygen gradient at the buffer - biofilm interface and the average oxygen concentration in the biofilm amounted to 50 μM.

Rapid DNA extraction from dried blood spots on filter paper: potential applications in biobanking.

PubMed

Choi, Eun-Hye; Lee, Sang Kwang; Ihm, Chunhwa; Sohn, Young-Hak

2014-12-01

Dried blood spot (DBS) technology is a microsampling alternative to traditional plasma or serum sampling for pharmaco- or toxicokinetic evaluation. DBS technology has been applied to diagnostic screening in drug discovery, nonclinical, and clinical settings. We have developed an improved elution protocol involving boiling of blood spots dried on Whatman filter paper. The purpose of this study was to compare the quality, purity, and quantity of DNA isolated from frozen blood samples and DBSs. We optimized a method for extraction and estimation of DNA from blood spots dried on filter paper (3-mm FTA card). A single DBS containing 40 μL blood was used. DNA was efficiently extracted in phosphate-buffered saline (PBS) or Tris-EDTA (TE) buffer by incubation at 37°C overnight. DNA was stable in DBSs that were stored at room temperature or frozen. The housekeeping genes GAPDH and beta-actin were used as positive standards for polymerase chain reaction (PCR) validation of general diagnostic screening. Our simple and convenient DBS storage and extraction methods are suitable for diagnostic screening by using very small volumes of blood collected on filter paper, and can be used in biobanks for blood sample storage.

Formulation and stability of an extemporaneous 0.02% chlorhexidine digluconate ophthalmic solution.

PubMed

Lin, Shu-Chiao; Huang, Chih-Fen; Shen, Li-Jiuan; Wang, Hsueh-Ju; Lin, Chia-Yu; Wu, Fe-Lin Lin

2015-12-01

Acanthamoeba keratitis is difficult to treat because Acanthamoeba cysts are resistant to the majority of antimicrobial agents. Despite the efficacy of 0.02% chlorhexidine in treating Acanthamoeba keratitis, a lack of data in the literature regarding the formulation's stability limits its clinical use. The objective of this study was to develop an optimal extemporaneous 0.02% chlorhexidine digluconate ophthalmic formulation for patients in need. With available active pharmaceutical ingredients, 0.02% chlorhexidine digluconate sample solutions were prepared by diluting with BSS Plus Solution or acetate buffer. Influences of the buffer, type of container, and temperature under daily-open condition were assessed based on the changes of pH values and chlorhexidine concentrations of the test samples weekly. To determine the beyond-use date, the optimal samples were stored at 2-8°C or room temperature, and analyzed at time 0 and at Week 1, Week 2, Week 3, Week 4, Week 5, Week 8, Week 12, and Week 24. Despite chlorhexidine exhibiting better stability in acetate buffer than in BSS solution, its shelf-life was < 14 days when stored in a light-resistant low-density polyethylene container. The acetate-buffered 0.02% chlorhexidine digluconate solution stored in light-resistant high-density polyethylene eyedroppers did not exhibit significant changes in pH or strength at any time interval. The acetate-buffered 0.02% chlorhexidine digluconate ophthalmic solution stored in light-resistant high-density polyethylene eyedroppers demonstrated excellent stability at 2-25°C for 6 months after being sealed and for 1 month after opening. This finding will enable us to prepare 0.02% chlorhexidine digluconate ophthalmic solutions based on a doctor's prescription. Copyright © 2014. Published by Elsevier B.V.

Enzyme kinetics in acoustically levitated droplets of supercooled water: a novel approach to cryoenzymology.

PubMed

Weis, David D; Nardozzi, Jonathan D

2005-04-15

The rate of the alkaline phosphatase-catalyzed hydrolysis of 4-methylumbelliferone phosphate was measured in acoustically levitated droplets of aqueous tris (50 mM) at pH 8.5 at 22 +/- 2 degrees C and in supercooled solution at -6 +/- 2 degrees C. At 22 degrees C, the rate of product formation was in excellent agreement with the rate observed in bulk solution in a cuvette, indicating that the acoustic levitation process does not alter the enzyme activity. The rate of the reaction decreased 6-fold in supercooled solution at -6 +/- 2 degrees C. The acoustic levitator apparatus is described in detail.

Effect of degree of esterification of pectin and calcium amount on drug release from pectin-based matrix tablets.

PubMed

Sungthongjeen, Srisagul; Sriamornsak, Pornsak; Pitaksuteepong, Tasana; Somsiri, Atawit; Puttipipatkhachorn, Satit

2004-02-12

The aim of this work was to assess the effect of 2 formulation variables, the pectin type (with different degrees of esterification [DEs]) and the amount of calcium, on drug release from pectin-based matrix tablets. Pectin matrix tablets were prepared by blending indomethacin (a model drug), pectin powder, and various amounts of calcium acetate and then tableting by automatic hydraulic press machine. Differential scanning calorimetry, powder x-ray diffraction, and Fourier transformed-infrared spectroscopy studies of the compressed tablets revealed no drug-polymer interaction and the existence of drug with low crystallinity. The in-vitro release studies in phosphate buffer (United States Pharmacopeia) and tris buffer indicated that the lower the DE, the greater the time for 50% of drug release (T50). This finding is probably because of the increased binding capacity of pectin to calcium. However, when the calcium was excluded, the pectins with different DEs showed similar release pattern with insignificant difference of T50. When the amount of calcium acetate was increased from 0 to 12 mg/tablet, the drug release was significantly slower. However, a large amount of added calcium (ie, 24 mg/tablet) produced greater drug release because of the partial disintegration of tablets. The results were more pronounced in phosphate buffer, where the phosphate ions induced the precipitation of calcium phosphate. In conclusion, both pectin type and added calcium affect the drug release from the pectin-based matrix tablets.

Nonclinical safety evaluation of boric acid and a novel borate-buffered contact lens multi-purpose solution, Biotrue™ multi-purpose solution.

PubMed

Lehmann, David M; Cavet, Megan E; Richardson, Mary E

2010-12-01

Multipurpose solutions (MPS) often contain low concentrations of boric acid as a buffering agent. Limited published literature has suggested that boric acid and borate-buffered MPS may alter the corneal epithelium; an effect attributed to cytotoxicity induced by boric acid. However, this claim has not been substantiated. We investigated the effect of treating cells with relevant concentrations of boric acid using two cytotoxicity assays, and also assessed the impact of boric acid on corneal epithelial barrier function by measuring TEER and immunostaining for tight junction protein ZO-1 in human corneal epithelial cells. Boric acid was also assessed in an in vivo ocular model when administered for 28 days. Additionally, we evaluated Biotrue multi-purpose solution, a novel borate-buffered MPS, alone and with contact lenses for ocular compatibility in vitro and in vivo. Boric acid passed both cytotoxicity assays and did not alter ZO-1 distribution or corneal TEER. Furthermore, boric acid was well-tolerated on-eye following repeated administration in a rabbit model. Finally, Biotrue multi-purpose solution demonstrated good ocular biocompatibility both in vitro and in vivo. This MPS was not cytotoxic and was compatible with the eye when administered alone and when evaluated with contact lenses. We demonstrate that boric acid and a borate-buffered MPS is compatible with the ocular environment. Our findings provide evidence that ocular effects reported for some borate-buffered MPS may be incorrectly attributed to boric acid and are more likely a function of the unique combination of ingredients in the MPS formulation tested. Copyright © 2010 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

High Temperature Superconducting Compounds

DTIC Science & Technology

1992-11-30

broadened interest in superconductivity in both the engineering and scientific communities. Superconducting materials may be offered as a solution to a...YBa2Cu307- has been made. For yttrium, the tris( isopropoxide ) was used exclusively, while the use of both Ba(O-i-Pr)2 and Ba(OCH2Ch2OEt)2 (prepared in... solutions of Cu(acac)2, Ba(OCH2CH 2OEt)2 , and Y(O-i-Pr)3 were spin coated on SrTiO 3 (100) and fired under oxygen to give oriented (b axis normal to the

Buffer capacity of biologics--from buffer salts to buffering by antibodies.

PubMed

Karow, Anne R; Bahrenburg, Sven; Garidel, Patrick

2013-01-01

Controlling pH is essential for a variety of biopharmaceutical process steps. The chemical stability of biologics such as monoclonal antibodies is pH-dependent and slightly acidic conditions are favorable for stability in a number of cases. Since control of pH is widely provided by added buffer salts, the current study summarizes the buffer characteristics of acetate, citrate, histidine, succinate, and phosphate buffers. Experimentally derived values largely coincide with values calculated from a model that had been proposed in 1922 by van Slyke. As high concentrated protein formulations become more and more prevalent for biologics, the self-buffering potential of proteins becomes of relevance. The current study provides information on buffer characteristics for pH ranges down to 4.0 and up to 8.0 and shows that a monoclonal antibody at 50 mg/mL exhibits similar buffer capacity as 6 mM citrate or 14 mM histidine (pH 5.0-6.0). Buffer capacity of antibody solutions scales linearly with protein concentration up to more than 200 mg/mL. At a protein concentration of 220 mg/mL, the buffer capacity resembles the buffer capacity of 30 mM citrate or 50 mM histidine (pH 5.0-6.0). The buffer capacity of monoclonal antibodies is practically identical at the process relevant temperatures 5, 25, and 40°C. Changes in ionic strength of ΔI=0.15, in contrast, can alter the buffer capacity up to 35%. In conclusion, due to efficient self-buffering by antibodies in the pH range of favored chemical stability, conventional buffer excipients could be dispensable for pH stabilization of high concentrated protein solutions. Copyright © 2013 American Institute of Chemical Engineers.

Facile solution synthesis of hexagonal Alq3 nanorods and their field emission properties.

PubMed

Hu, Jin-Song; Ji, Heng-Xing; Cao, An-Min; Huang, Zheng-Xi; Zhang, Yang; Wan, Li-Jun; Xia, An-Dong; Yu, Da-Peng; Meng, Xiang-Min; Lee, Shuit-Tong

2007-08-07

A facile self-assembly growth route assisted by surfactant has been developed to synthesize tris(8-hydroxyquinoline)aluminium (Alq(3)) nanorods with regular hexagonal shape and good crystallinity, which exhibit field-emission characteristics with a very low turn-on field of ca. 3.1 V microm(-1) and a high field-enhancement factor of ca. 1300.

Affinity Probe Capillary Electrophoresis Evaluation of Aptamer Binding to Campylobacter jejuni Bacteria

DTIC Science & Technology

2009-11-01

absorption coefficients (260nm) of 173,100 M cm–1. Desired stock solutions were freshly prepared with tris- borate ethylenediaminetetraacetic acid (EDTA... McMasters , and Paul M. Pellegrino ARL-TR-5015 November 2009 Approved for public release...Aptamer Binding to Campylobacter jejuni Bacteria Dimitra N. Stratis-Cullum, Sun McMasters , and Paul M. Pellegrino Sensors and Electron Devices

40 CFR 63.9804 - What are my monitoring system installation, operation, and maintenance requirements?

Code of Federal Regulations, 2014 CFR

2014-07-01

... accuracy that is traceable to National Institute of Standards and Technology (NIST) standards. (ii) The... section. (i) Perform a single-point calibration using an NIST-certified buffer solution that is accurate... include a redundant pH sensor, perform a single point calibration using an NIST-certified buffer solution...

40 CFR 63.9804 - What are my monitoring system installation, operation, and maintenance requirements?

Code of Federal Regulations, 2013 CFR

2013-07-01

... accuracy that is traceable to National Institute of Standards and Technology (NIST) standards. (ii) The... section. (i) Perform a single-point calibration using an NIST-certified buffer solution that is accurate... include a redundant pH sensor, perform a single point calibration using an NIST-certified buffer solution...

A Pollutant Transformation Laboratory Exercise for Environmental Chemistry: The Reduction of Nitrobenzenes by Anaerobic Solutions of Humic Acid

ERIC Educational Resources Information Center

Dunnivant, Frank M.; Reynolds, Mark-Cody

2007-01-01

The laboratory experiment, which acts as a capstone, integrated lecture-laboratory exercise involving solution preparation, pH buffers, [E[subscript]H] (reduction potential) buffers, organic reaction mechanisms, reaction kinetics, and instrumental analysis is presented. The students completing the lecture and laboratory exercises could gain a…

Crystal growth, structural, optical, spectral and thermal studies of tris(L-phenylalanine)L-phenylalaninium nitrate: a new organic nonlinear optical material.

PubMed

Prakash, M; Geetha, D; Lydia Caroline, M

2011-10-15

Tris(L-phenylalanine)L-phenylalaninium nitrate, C(9)H(12)NO(2)(+)·NO(3)(-)·3C(9)H(11)NO(2) (TPLPN), a new organic nonlinear optical material was grown from aqueous solution by slow evaporation solution growth at room temperature. The grown crystals were subjected to powder X-ray diffraction and single crystal X-ray diffraction studies to confirm the crystalline nature and crystal structure. The modes of vibration of different molecular groups present in TPLPN have been identified by FTIR spectral analysis. The presence of hydrogen and carbon in the grown crystal were confirmed by using proton and carbon nuclear magnetic resonance (NMR) spectral analyses. The optical transmission spectral study establishes good transmitting ability of the crystal in the entire visible region. The thermogravimetric (TG) and differential thermal analyses (DTA) were carried out to understand the thermal stability of the sample. The nonlinear optical property of the compound observed using Kurtz powder second harmonic generation test assets the suitability of the grown material for the frequency conversion of laser radiation of Nd:YAG. Copyright © 2011 Elsevier B.V. All rights reserved.

Tris-(hydroxyamino)triazines: high-affinity chelating tridentate O,N,O-hydroxylamine ligand for the cis-V(V)O2(+) cation.

PubMed

Nikolakis, Vladimiros A; Exarchou, Vassiliki; Jakusch, Tamás; Woolins, J Derek; Slawin, Alexandra M Z; Kiss, Tamás; Kabanos, Themistoklis A

2010-10-14

The treatment of the trichloro-1,3,5-triazine with N-methylhydroxylamine hydrochloride results in the replacement of the three chlorine atoms of the triazine ring with the function -N(OH)CH(3) yielding the symmetrical tris-(hydroxyamino)triazine ligand H(3)trihyat. Reaction of the ligand H(3)trihyat with NaV(V)O(3) in aqueous solution followed by addition of Ph(4)PCl gave the mononuclear vanadium(V) compound Ph(4)P[V(V)O(2)(Htrihyat)] (1). The structure of compound 1 was determined by X-ray crystallography and indicates that this compound has a distorted square-pyramidal arrangement around vanadium. The ligand Htrihyat(2-) is bonded to vanadium atom in a tridentate fashion at the triazine ring nitrogen atom and the two deprotonated hydroxylamido oxygen atoms. The high electron density of the triazine ring nitrogen atoms, which results from the resonative contribution of electrons of exocyclic nitrogen atoms, leads to a very strong V-N bond. The cis-[V(V)O(2)(Htrihyat)](-) species exhibits high hydrolytic stability in aqueous solution over a wide pH range, 2.5-11.5, as was evidenced by potentiometry.

Coefficient of Friction of Human Corneal Tissue.

PubMed

Wilson, Tawnya; Aeschlimann, Rudolf; Tosatti, Samuele; Toubouti, Youssef; Kakkassery, Joseph; Osborn Lorenz, Katherine

2015-09-01

A novel property evaluation methodology was used to determine the elusive value for the human corneal coefficient of friction (CoF). Using a microtribometer on 28 fresh human donor corneas with intact epithelia, the CoF was determined in 4 test solutions (≥5 corneas/solution): tear-mimicking solution (TMS) in borate-buffered saline (TMS-PS), TMS in phosphate-buffered saline (TMS-PBS), TMS with HEPES-buffered saline (TMS-HEPES), and tear-like fluid in PBS (TLF-PBS). Mean (SD) CoF values ranged from 0.006 to 0.015 and were 0.013 (0.010) in TMS-PS, 0.006 (0.003) in TMS-PBS, 0.014 (0.005) in TMS-HEPES, and 0.015 (0.009) in TLF-PBS. Statistically significant differences were shown for TMS-PBS versus TLF (P = 0.0424) and TMS-PBS versus TMS-HEPES (P = 0.0179), but not for TMS-PBS versus TMS-PS (P = 0.2389). Successful measurement of the fresh human corneal tissue CoF was demonstrated, with values differing in the evaluated buffer solutions, within this limited sample size.

Pyrroloquinoline quinone (PQQ) is reduced to pyrroloquinoline quinol (PQQH2) by vitamin C, and PQQH2 produced is recycled to PQQ by air oxidation in buffer solution at pH 7.4.

PubMed

Mukai, Kazuo; Ouchi, Aya; Nagaoka, Shin-ichi; Nakano, Masahiko; Ikemoto, Kazuto

2016-01-01

Measurements of the reaction of sodium salt of pyrroloquinoline quinone (PQQNa2) with vitamin C (Vit C) were performed in phosphate-buffered solution (pH 7.4) at 25 °C under nitrogen atmosphere, using UV-vis spectrophotometry. The absorption spectrum of PQQNa2 decreased in intensity due to the reaction with Vit C and was changed to that of pyrroloquinoline quinol (PQQH2, a reduced form of PQQ). One molecule of PQQ was reduced by two molecules of Vit C producing a molecule of PQQH2 in the buffer solution. PQQH2, thus produced, was recycled to PQQ due to air oxidation. PQQ and Vit C coexist in many biological systems, such as vegetables, fruits, as well as in human tissues. The results obtained suggest that PQQ is reduced by Vit C and functions as an antioxidant in biological systems, because it has been reported that PQQH2 shows very high free-radical scavenging and singlet-oxygen quenching activities in buffer solutions.

The formation of stable pH gradients with weak monovalent buffers for isoelectric focusing in free solution

NASA Technical Reports Server (NTRS)

Mosher, Richard A.; Thormann, Wolfgang; Graham, Aly; Bier, Milan

1985-01-01

Two methods which utilize simple buffers for the generation of stable pH gradients (useful for preparative isoelectric focusing) are compared and contrasted. The first employs preformed gradients comprised of two simple buffers in density-stabilized free solution. The second method utilizes neutral membranes to isolate electrolyte reservoirs of constant composition from the separation column. It is shown by computer simulation that steady-state gradients can be formed at any pH range with any number of components in such a system.

Assessment of Mexican Arnica (Heterotheca inuloides Cass) and Rosemary (Rosmarinus officinalis) Extracts on Dopamine and Selected Biomarkers of Oxidative Stress in Stomach and Brain of Salmonella typhimurium Infected rats.

PubMed

Guzmàn, David Calderón; Herrera, Maribel Ortiz; Brizuela, Norma Osnaya; Mejía, Gerardo Barragàn; García, Ernestina Hernàndez; Olguín, Hugo Juàrez; Peraza, Armando Valenzuela; Ruíz, Norma Labra; Del Angel, Daniel Santamaría

2017-01-01

The effects of some natural products on dopamine (DA) and 5-hydroxyindole acetic acid (5-HIAA) in brain of infected models are still unclear. The purpose of this study was to measure the effect of Mexican arnica/rosemary (MAR) water extract and oseltamivir on both biogenic amines and some oxidative biomarkers in the brain and stomach of young rats under infection condition. Female Wistar rats (weight 80 g) in the presence of MAR or absence (no-MAR) were treated as follows: group 1, buffer solution (controls); oseltamivir (100 mg/kg), group 2; culture of Salmonella typhimurium ( S.Typh ) (1 × 10 6 colony-forming units/rat) group 3; oseltamivir (100 mg/kg) + S.Typh (same dose) group 4. Drug and extracts were administered intraperitoneally every 24 h for 5 days, and S.Typh was given orally on days 1 and 3. On the fifth day, blood was collected to measure glucose and hemoglobin. The brains and stomachs were obtained to measure levels of DA, 5-HIAA, glutathione (GSH), TBARS, H 2 O 2 , and total ATPase activity using validated methods. DA levels increased in MAR group treated with oseltamivir alone but decreased in no-MAR group treated with oseltamivir plus S.Typh . 5-HIAA, GSH, and H 2 O 2 decreased in this last group, and ATPase activity increased in MAR group treated with oseltamivir plus S.Typh . TBARS (lipid peroxidation) increased in MAR group that received oseltamivir alone. Most of the biomarkers were not altered significantly in the stomach. MAR extract alters DA and metabolism of 5-HIAA in the brain of young animals infected. Antioxidant capacity may be involved in these effects. The purpose of this study was to measure the effect of Mexican arnica/rosemary water extract and oseltamivir on both biogenic amines and some oxidative biomarkers in the brain and stomach of young rats under infection condition. Results: Mexican arnica and rosemary extract alter dopamine and metabolism of 5-HIAA in the brain of young animals infected. Antioxidant capacity may be involved in these effects. Abbreviations used: AS: Automated system, ATP: Adenosine triphosphate, CNS: Central nervous system, CFU: Colony-forming unit, DA: Dopamine EDTA: Ethylenediaminetetraacetic acid, 5-HIAA: Äcido 5-hidroxindolacético (serotonina), GABA: γ-aminobutyric acid, GSH: Glutathione, H2O2: Hidrogen peroxide, HCLO4: Perchloric acid, iNOS: Inducible nitric oxide synthase, LPS: Lipopolysaccharides, MAR: Arnica/Rosemary, NaCl: Sodium Chloride, NOGSH: nitrosoglutathione, NOS: Nitric oxide, OPT: Ortho-phtaldialdehyde, Pbs: Phosphate buffered saline, pH: potential of Hydrogen, Pi: Inorganic phosphate, ROS: Reactive oxygen species, RNSs: Reactive nitrogen species Tba: Thiobarbaturic acid, TBARS: Thiobarbituric aid reactive, Tca: Trichloroacetic, Tris-HCL: Tris hydrochloride, TSA: Trypticasein Soya Agar.

Assessment of Mexican Arnica (Heterotheca inuloides Cass) and Rosemary (Rosmarinus officinalis) Extracts on Dopamine and Selected Biomarkers of Oxidative Stress in Stomach and Brain of Salmonella typhimurium Infected rats

PubMed Central

Guzmàn, David Calderón; Herrera, Maribel Ortiz; Brizuela, Norma Osnaya; Mejía, Gerardo Barragàn; García, Ernestina Hernàndez; Olguín, Hugo Juàrez; Peraza, Armando Valenzuela; Ruíz, Norma Labra; Del Angel, Daniel Santamaría

2017-01-01

Background: The effects of some natural products on dopamine (DA) and 5-hydroxyindole acetic acid (5-HIAA) in brain of infected models are still unclear. Objective: The purpose of this study was to measure the effect of Mexican arnica/rosemary (MAR) water extract and oseltamivir on both biogenic amines and some oxidative biomarkers in the brain and stomach of young rats under infection condition. Methods: Female Wistar rats (weight 80 g) in the presence of MAR or absence (no-MAR) were treated as follows: group 1, buffer solution (controls); oseltamivir (100 mg/kg), group 2; culture of Salmonella typhimurium (S.Typh) (1 × 106 colony-forming units/rat) group 3; oseltamivir (100 mg/kg) + S.Typh (same dose) group 4. Drug and extracts were administered intraperitoneally every 24 h for 5 days, and S.Typh was given orally on days 1 and 3. On the fifth day, blood was collected to measure glucose and hemoglobin. The brains and stomachs were obtained to measure levels of DA, 5-HIAA, glutathione (GSH), TBARS, H2O2, and total ATPase activity using validated methods. Results: DA levels increased in MAR group treated with oseltamivir alone but decreased in no-MAR group treated with oseltamivir plus S.Typh. 5-HIAA, GSH, and H2O2 decreased in this last group, and ATPase activity increased in MAR group treated with oseltamivir plus S.Typh. TBARS (lipid peroxidation) increased in MAR group that received oseltamivir alone. Most of the biomarkers were not altered significantly in the stomach. Conclusion: MAR extract alters DA and metabolism of 5-HIAA in the brain of young animals infected. Antioxidant capacity may be involved in these effects. SUMMARY The purpose of this study was to measure the effect of Mexican arnica/rosemary water extract and oseltamivir on both biogenic amines and some oxidative biomarkers in the brain and stomach of young rats under infection condition. Results: Mexican arnica and rosemary extract alter dopamine and metabolism of 5-HIAA in the brain of young animals infected. Antioxidant capacity may be involved in these effects. Abbreviations used: AS: Automated system, ATP: Adenosine triphosphate, CNS: Central nervous system, CFU: Colony-forming unit, DA: Dopamine EDTA: Ethylenediaminetetraacetic acid, 5-HIAA: Äcido 5-hidroxindolacético (serotonina), GABA: γ-aminobutyric acid, GSH: Glutathione, H2O2: Hidrogen peroxide, HCLO4: Perchloric acid, iNOS: Inducible nitric oxide synthase, LPS: Lipopolysaccharides, MAR: Arnica/Rosemary, NaCl: Sodium Chloride, NOGSH: nitrosoglutathione, NOS: Nitric oxide, OPT: Ortho-phtaldialdehyde, Pbs: Phosphate buffered saline, pH: potential of Hydrogen, Pi: Inorganic phosphate, ROS: Reactive oxygen species, RNSs: Reactive nitrogen species Tba: Thiobarbaturic acid, TBARS: Thiobarbituric aid reactive, Tca: Trichloroacetic, Tris-HCL: Tris hydrochloride, TSA: Trypticasein Soya Agar PMID:28539708

40 CFR 721.10493 - Tris-alkyl-alkoxy melamine polymer (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Tris-alkyl-alkoxy melamine polymer... Specific Chemical Substances § 721.10493 Tris-alkyl-alkoxy melamine polymer (generic). (a) Chemical... as tris-alkyl-alkoxy melamine polymer (PMN P-05-417) is subject to reporting under this section for...

40 CFR 721.10493 - Tris-alkyl-alkoxy melamine polymer (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Tris-alkyl-alkoxy melamine polymer... Specific Chemical Substances § 721.10493 Tris-alkyl-alkoxy melamine polymer (generic). (a) Chemical... as tris-alkyl-alkoxy melamine polymer (PMN P-05-417) is subject to reporting under this section for...

Crystallization of calcium oxalate dihydrate in a buffered calcium-containing glucose solution by irradiation with non-equilibrium atmospheric pressure plasma

NASA Astrophysics Data System (ADS)

Kurake, Naoyuki; Tanaka, Hiromasa; Ishikawa, Kenji; Nakamura, Kae; Kajiyama, Hiroaki; Kikkawa, Fumitaka; Mizuno, Masaaki; Ikehara, Yuzuru; Hori, Masaru

2017-10-01

Oxalate was synthesized in the glucose solution by irradiation with non-equilibrium atmospheric pressure plasma (NEAPP), in which the NEAPP plume contacted the solution surface, via the generation of several intermediate organic products such as gluconic acid. A thermodynamically unstable phase of calcium oxalate dihydrate crystallized rapidly during incubation of a NEAPP-irradiated glucose solution that contained calcium ions and was buffered at neutral pH. Longer irradiation times increased the growth rate and the number of seed crystals.

Effects of hypertonic buffer composition on lymph node uptake and bioavailability of rituximab, after subcutaneous administration.

PubMed

Fathallah, Anas M; Turner, Michael R; Mager, Donald E; Balu-Iyer, Sathy V

2015-03-01

The subcutaneous administration of biologics is highly desirable; however, incomplete bioavailability after s.c. administration remains a major challenge. In this work we investigated the effects of excipient dependent hyperosmolarity on lymphatic uptake and plasma exposure of rituximab as a model protein. Using Swiss Webster (SW) mice as the animal model, we compared the effects of NaCl, mannitol and O-phospho-L-serine (OPLS) on the plasma concentration of rituximab over 5 days after s.c. administration. An increase was observed in plasma concentrations in animals administered rituximab in hypertonic buffer solutions, compared with isotonic buffer. Bioavailability, as estimated by our pharmacokinetic model, increased from 29% in isotonic buffer to 54% in hypertonic buffer containing NaCl, to almost complete bioavailability in hypertonic buffers containing high dose OPLS or mannitol. This improvement in plasma exposure is due to the improved lymphatic trafficking as evident from the increase in the fraction of dose trafficked through the lymph nodes in the presence of hypertonic buffers. The fraction of the dose trafficked through the lymphatics, as estimated by the model, increased from 0.05% in isotonic buffer to 13% in hypertonic buffer containing NaCl to about 30% for hypertonic buffers containing high dose OPLS and mannitol. The data suggest that hypertonic solutions may be a viable option for improving s.c. bioavailability. Copyright © 2014 John Wiley & Sons, Ltd.

Effects of hypertonic buffer composition on lymph node uptake and bioavailability of rituximab, after subcutaneous administration

PubMed Central

Fathallah, Anas M.; Turner, Michael R.; Balu-Iyer, Sathy V.

2015-01-01

Subcutaneous administration of biologics is highly desirable; however, incomplete bioavailability after sc administration remains a major challenge. In this work we investigated the effects of excipient dependent hyper-osmolarity on lymphatic uptake and plasma exposure of rituximab as a model protein. Using Swiss Webster (SW) mice as our animal model, we compared the effects of NaCl, mannitol and, O-Phospho-L-Serine (OPLS) on plasma concentration of rituximab over 5 days after sc administration. We observed an increase in plasma concentrations in animals administered rituximab in hypertonic buffer solutions, as compared to isotonic buffer. Bioavailability, as estimated by our pharmacokinetic model, increased from 29% in isotonic buffer to 54% in hypertonic buffer containing NaCl, to almost complete bioavailability in hypertonic buffers containing high dose OPLS or mannitol. This improvement in plasma exposure is due to improved lymphatic trafficking as evident from the increase in the fraction of dose trafficked through the lymph node in the presence of hypertonic buffers. The fraction of the dose trafficked through the lymphatic, as estimated by the model, increased from 0.05 % in isotonic buffer to 13% in hyper-tonic buffer containing NaCl to about 30% for hypertonic buffers containing high dose OPLS and mannitol. Our data suggests that hypertonic solutions may be a viable option to improve sc bioavailability. PMID:25377184

A homologous series of regioselectively tetradeprotonated group 8 metallocenes: new inverse crown ring compounds synthesized via a mixed sodium-magnesium tris(diisopropylamide) synergic base.

PubMed

Andrikopoulos, Prokopis C; Armstrong, David R; Clegg, William; Gilfillan, Carly J; Hevia, Eva; Kennedy, Alan R; Mulvey, Robert E; O'Hara, Charles T; Parkinson, John A; Tooke, Duncan M

2004-09-22

Subjecting ferrocene, ruthenocene, or osmocene to the synergic amide base sodium-magnesium tris(diisopropylamido) affords a unique homologous series of metallocene derivatives of general formula [(M(C(5)H(3))(2))Na(4)Mg(4)(i-Pr(2)N)(8)] (where M = Fe (1), Ru (2), or Os (3)). X-ray crystallographic studies of 1-3 reveal a common molecular "inverse crown" structure comprising a 16-membered [(NaNMgN)(4)](4+) "host" ring and a metallocenetetraide [M(C(5)H(3))(2)](4-) "guest" core, the cleaved protons of which are lost selectively from the 1, 1', 3, and 3'-positions. Variable-temperature NMR spectroscopic studies indicate that 1, 2, and 3 each exist as two distinct interconverting conformers in arene solution, the rates of exchange of which have been calculated using coalescence and EXSY NMR measurements.

Intermolecular interactions and aggregation of fac-tris(2-phenylpyridinato-C2,N)iridium(III) in nonpolar solvents.

PubMed

Takayasu, Satoshi; Suzuki, Takayoshi; Shinozaki, Kazuteru

2013-08-15

The intermolecular interaction and aggregation of the neutral complex fac-tris(2-phenylpyridinato-C(2),N)iridium(III) (fac-Ir(ppy)3) in solution was investigated. Intermolecular interactions were found to effectively decrease the luminescence lifetime via self-quenching with increasing fac-Ir(ppy)3 concentrations. A Stern-Volmer plot for quenching in acetonitrile was linear, due to bimolecular self-quenching, but curved in toluene as the result of excimer formation. (1)H NMR spectra demonstrated a monomer-aggregate equilibrium which resulted in spectral shifts depending on solvent polarity. X-ray crystallography provided structural information concerning the aggregate, which is based on a tetramer consisting of two Δ-fac-Ir(ppy)3-Λ-fac-Ir(ppy)3 pairs. Offset π-π stacking of ppy ligands and electrostatic dipole-dipole interactions between complex molecules play an important role in the formation of these molecular pairs.

Hydrogen production in microbial reverse-electrodialysis electrolysis cells using a substrate without buffer solution.

PubMed

Song, Young-Hyun; Hidayat, Syarif; Kim, Han-Ki; Park, Joo-Yang

2016-06-01

The aim of this work was to use substrate without buffer solution in a microbial reverse-electrodialysis electrolysis cell (MREC) for hydrogen production under continuous flow condition (10 cell pairs of RED stacks, HRT=5, 7.5, and 15h). Decreasing in the HRT (increasing in the organic matter) made cell current stable and increased. Hydrogen gas was produced at a rate of 0.61m(3)-H2/m(3)-Van/d in H-MREC, with a COD removal efficiency of 81% (1.55g/L/d) and a Coulombic efficiency of 41%. This MREC system without buffer solution could successfully produce hydrogen gas at a consistent rate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dynamics of diamond nanoparticles in solution and cells.

PubMed

Neugart, Felix; Zappe, Andrea; Jelezko, Fedor; Tietz, C; Boudou, Jean Paul; Krueger, Anke; Wrachtrup, Jörg

2007-12-01

The fluorescence and motional dynamics of single diamond nanocrystals in buffer solution and in living cells is investigated. Stable hydrosols of nanodiamonds in buffer solutions are investigated by fluorescence correlation spectroscopy. Measurement of the effective hydrodynamic radius yields particles of 48 nm diameter, which is in excellent agreement with atomic force microscopy measurements made on the same particles. Fluorescence correlation spectroscopy measurements indicate that nanocrystals easily form aggregates when the buffer pH is changed. This tendency is reduced when the surface of the diamonds is covered with surfactants. Upon incubation, cells spontaneously take up nanocrystals that uniformly distribute in cells. Most of the particles get immobilized within a few minutes. The binding of streptavidin to biotinylated aggregates of 4 nm diameter nanodiamonds is demonstrated.

Chemical micro-sensor

DOEpatents

Ruggiero, Anthony J.

2005-05-03

An integrated optical capillary electrophoresis system for analyzing an analyte. A modulated optical pump beam impinges on an capillary containing the analyte/buffer solution which is separated by electrophoresis. The thermally-induced change in the index of refraction of light in said electrophoresis capillary is monitored using an integrated micro-interferometer. The interferometer includes a first interferometer arm intersecting the electrophoresis capillary proximate the excitation beam and a second, reference interferometer arm. Changes in index of refraction in the analyte measured by interrogating the interferometer state using white light interferometry and a phase-generated carrier demodulation technique. Background thermo-optical activity in the buffer solution is cancelled by splitting the pump beam and exciting pure buffer solution in a second section of capillary where it crosses the reference arm of the interferometer.

Method for detecting coliform organisms

NASA Technical Reports Server (NTRS)

Nishioka, K.; Nibley, D. A.; Jeffers, E. L.; Brooks, R. L. (Inventor)

1983-01-01

A method and apparatus are disclosed for determining the concentration of coliform bacteria in a sample. The sample containing the coliform bacteria is cultured in a liquid growth medium. The cultured bacteria produce hydrogen and the hydrogen is vented to a second cell containing a buffer solution in which the hydrogen dissolves. By measuring the potential change in the buffer solution caused by the hydrogen, as a function of time, the initial concentration of bacteria in the sample is determined. Alternatively, the potential change in the buffer solution can be compared with the potential change in the liquid growth medium to verify that the potential change in the liquid growth medium is produced primarily by the hydrogen gas produced by the coliform bacteria.

Photoelectrodialytic cell

DOEpatents

Murphy, George W.

1983-01-01

A multicompartment photoelectrodialytic demineralization cell is provided with a buffer compartment interposed between the product compartment and a compartment containing an electrolyte solution. Semipermeable membranes separate the buffer compartment from the product and electrolyte compartments. The buffer compartment is flushed to prevent leakage of the electrolyte compartment from entering the product compartment.

SALICYLATE PROCESS FOR THORIUM SEPARATION FROM RARE EARTHS

DOEpatents

Cowan, G.A.

1959-08-25

The separation of thorium from rare earths is accomplished by forming an aqueous solution of salts of thorium and rare earths and sufficient acetate buffer to provide a pH of between 2 and 5, adding an ammonium salicylate to the aqueous buffered solution, contacting the resultant solution with a substantially water-immiscible organic solvent mixture of an ether and an ester, and separating the solvent extract phase containing thorium salicylate from the aqueous phase containing the rare earths.

European Organisation for Research and Treatment of Cancer (EORTC) Pathobiology Group standard operating procedure for the preparation of human tumour tissue extracts suited for the quantitative analysis of tissue-associated biomarkers.

PubMed

Schmitt, Manfred; Mengele, Karin; Schueren, Elisabeth; Sweep, Fred C G J; Foekens, John A; Brünner, Nils; Laabs, Juliane; Malik, Abha; Harbeck, Nadia

2007-03-01

With the new concept of 'individualized treatment and targeted therapies', tumour tissue-associated biomarkers have been given a new role in selection of cancer patients for treatment and in cancer patient management. Tumour biomarkers can give support to cancer patient stratification and risk assessment, treatment response identification, or to identifying those patients who are expected to respond to certain anticancer drugs. As the field of tumour-associated biomarkers has expanded rapidly over the last years, it has become increasingly apparent that a strong need exists to establish guidelines on how to easily disintegrate the tumour tissue for assessment of the presence of tumour tissue-associated biomarkers. Several mechanical tissue (cell) disruption techniques exist, ranging from bead mill homogenisation and freeze-fracturing through to blade or pestle-type homogenisation, to grinding and ultrasonics. Still, only a few directives have been given on how fresh-frozen tumour tissues should be processed for the extraction and determination of tumour biomarkers. The PathoBiology Group of the European Organisation for Research and Treatment of Cancer therefore has devised a standard operating procedure for the standardised preparation of human tumour tissue extracts which is designed for the quantitative analysis of tumour tissue-associated biomarkers. The easy to follow technical steps involved require 50-300 mg of deep-frozen cancer tissue placed into small size (1.2 ml) cryogenic tubes. These are placed into the shaking flask of a Mikro-Dismembrator S machine (bead mill) to pulverise the tumour tissue in the capped tubes in the deep-frozen state by use of a stainless steel ball, all within 30 s of exposure. RNA is isolated from the pulverised tissue following standard procedures. Proteins are extracted from the still frozen pulverised tissue by addition of Tris-buffered saline to obtain the cytosol fraction of the tumour or by the Tris buffer supplemented with the non-ionic detergent Triton X-100, and, after high-speed centrifugation, are found in the tissue supernatant. The resulting tissue cell debris sediment is a rich source of genomic DNA.

Preparation and optimization of self-assembled chondroitin sulfate-nisin nanogel based on quality by design concept.

PubMed

Mohtashamian, Shahab; Boddohi, Soheil; Hosseinkhani, Saman

2018-02-01

Self-assembled nanogel was prepared by electrostatic complexation of two oppositely charged biological macromolecules, which were cationic nisin and anionic chondroitin sulfate (ChS). The critical factors affected the physical properties of ChS-nisin nanogel was screened and optimized by Plackett-Burman design (PB) and central composite design (CCD). The independent factors selected were: concentration ratio of nisin to ChS, injection rate of nisin solution, buffer solvent type, magnetic stirring rate, pH of initial buffer solution, centrifuge-cooling temperature, and centrifuge rotation speed. Among these factors, concentration ratio changed the entrapment efficiency and loading capacity significantly. In addition, the hydrodynamic diameter and loading capacity were significantly influenced by injection rate and pH of initial buffer solution. The optimized nanogel structure was obtained by concentration ratio of 6.4mg/mL nisin to 1mg/mL ChS, pH of buffer solution at 4.6, and nisin solution injection rate of 0.2mL/min. The observed values of dependent responses were close to predicted values confirmed by model from response surface methodology. The results obviously showed that quality by design concept (QbD) could be effectively applied to optimize the developed ChS-nisin nanogel. Copyright © 2017 Elsevier B.V. All rights reserved.

Biodesulfurization of vanadium-bearing titanomagnetite concentrates and pH control of bioleaching solution

NASA Astrophysics Data System (ADS)

Liu, Xiao-rong; Jiang, Sheng-cai; Liu, Yan-jun; Li, Hui; Wang, Hua-jun

2013-10-01

Vanadium-bearing titanomagnetite concentrates were desulfurized with Acidithiobacillus ferrooxidans ( A. ferrooxidans). The sulfur content of the concentrates was reduced from 0.69wt% to 0.14wt% after bioleaching for 15 d with a 10% pulp density at 30°C. Maintaining a stable pH value during biodesulfurization was critical because of high acid consumption, resulting from a combination of nonoxidative and oxidative dissolution of pyrrhotite in acid solution. It is discovered that the citric acid-disodium hydrogen phosphate buffer of pH 2.0 can control the solution pH value smoothly in the optimal range of 2.0-3.0 for A. ferrooxidans growth. Using the buffer in the volume fraction range of 5.0%-15.0% stimulates A. ferrooxidans growth and improves the biodesulfurization efficiency. Compared with the buffer-free control case, the maximum increase of biodesulfurization rate is 29.7% using a 10.0vol% buffer. Bioleaching provides an alternative process for desulfurization of vanadium-bearing titanomagnetite ores.

Photoelectrodialytic cell

DOEpatents

Murphy, G.W.

1983-09-13

A multicompartment photoelectrodialytic demineralization cell is provided with a buffer compartment interposed between the product compartment and a compartment containing an electrolyte solution. Semipermeable membranes separate the buffer compartment from the product and electrolyte compartments. The buffer compartment is flushed to prevent leakage of the electrolyte compartment from entering the product compartment. 3 figs.

A Unified Kinetics and Equilibrium Experiment: Rate Law, Activation Energy, and Equilibrium Constant for the Dissociation of Ferroin

ERIC Educational Resources Information Center

Sattar, Simeen

2011-01-01

Tris(1,10-phenanthroline)iron(II) is the basis of a suite of four experiments spanning 5 weeks. Students determine the rate law, activation energy, and equilibrium constant for the dissociation of the complex ion in acid solution and base dissociation constant for phenanthroline. The focus on one chemical system simplifies a daunting set of…

On the delay analysis of a TDMA channel with finite buffer capacity

NASA Technical Reports Server (NTRS)

Yan, T.-Y.

1982-01-01

The throughput performance of a TDMA channel with finite buffer capacity for transmitting data messages is considered. Each station has limited message buffer capacity and has Poisson message arrivals. Message arrivals will be blocked if the buffers are congested. Using the embedded Markov chain model, the solution procedure for the limiting system-size probabilities is presented in a recursive fashion. Numerical examples are given to demonstrate the tradeoffs between the blocking probabilities and the buffer sizing strategy.

Neurotoxicological and thyroid evaluations of rats developmentally exposed to tris(1,3-dichloro-2-propyl)phosphate (TDICPP) and tris(2-chloro-2-ethyl)phosphate(TCEP)

EPA Science Inventory

ABSTRACT: Tris(1,3-dichloro-2-propyl)phosphate (TDICPP) and tris(2-chloro-2-ethyl)phosphate (TCEP) are organophosphorous flame retardants with widespread usage and human exposures through food, inhalation, and dust ingestion. They have been detected in human tissues including ur...

40 CFR Appendix B to Subpart Nnn... - Free Formaldehyde Analysis of Insulation Resins by Hydroxylamine Hydrochloride

Code of Federal Regulations, 2011 CFR

2011-07-01

... 4.0 with pH 4.0 buffer and pH 7 with pH 7.0 buffer. 3.350-mL burette for 1.0 N sodium hydroxide. 3... hydrochloride solution, 100 grams per liter, pH adjusted to 4.00. 4.3Hydrochloric acid solution, 1.0 N and 0.1 N... magnetic stirrer. Confirm that the resin has dissolved. 5.4Adjust the resin/solvent solution to pH 4.0...

40 CFR Appendix B to Subpart Nnn... - Free Formaldehyde Analysis of Insulation Resins by Hydroxylamine Hydrochloride

Code of Federal Regulations, 2010 CFR

2010-07-01

... 4.0 with pH 4.0 buffer and pH 7 with pH 7.0 buffer. 3.350-mL burette for 1.0 N sodium hydroxide. 3... hydrochloride solution, 100 grams per liter, pH adjusted to 4.00. 4.3Hydrochloric acid solution, 1.0 N and 0.1 N... magnetic stirrer. Confirm that the resin has dissolved. 5.4Adjust the resin/solvent solution to pH 4.0...

CHEMICAL SOLUTION DEPOSITION BASED OXIDE BUFFERS AND YBCO COATED CONDUCTORS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paranthaman, Mariappan Parans

We have reviewed briefly the growth of buffer and high temperature superconducting oxide thin films using a chemical solution deposition (CSD) method. In the Rolling-Assisted Biaxially Textured Substrates (RABiTS) process, developed at Oak Ridge National Laboratory, utilizes the thermo mechanical processing to obtain the flexible, biaxially oriented copper, nickel or nickel-alloy substrates. Buffers and Rare Earth Barium Copper Oxide (REBCO) superconductors have been deposited epitaxially on the textured nickel alloy substrates. The starting substrate serves as a template for the REBCO layer, which has substantially fewer weak links. Buffer layers play a major role in fabricating the second generation REBCOmore » wire technology. The main purpose of the buffer layers is to provide a smooth, continuous and chemically inert surface for the growth of the REBCO film, while transferring the texture from the substrate to the superconductor layer. To achieve this, the buffer layers need to be epitaxial to the substrate, i.e. they have to nucleate and grow in the same bi-axial texture provided by the textured metal foil. The most commonly used RABiTS multi-layer architectures consist of a starting template of biaxially textured Ni-5 at.% W (Ni-W) substrate with a seed (first) layer of Yttrium Oxide (Y2O3), a barrier (second) layer of Yttria Stabilized Zirconia (YSZ), and a Cerium Oxide (CeO2) cap (third) layer. These three buffer layers are generally deposited using physical vapor deposition (PVD) techniques such as reactive sputtering. On top of the PVD template, REBCO film is then grown by a chemical solution deposition. This article reviews in detail about the list of oxide buffers and superconductor REBCO films grown epitaxially on single crystal and/or biaxially textured Ni-W substrates using a CSD method.« less

Bicarbonate- versus lactate-buffered solutions for acute continuous haemodiafiltration or haemofiltration.

PubMed

Tian, Jin Hui; Ma, Bin; Yang, KeHu; Liu, Yali; Tan, Jiying; Liu, Tian Xi

2015-03-05

Acute kidney injury (AKI) is a severe loss of kidney function that results in patients' inability to appropriately excrete nitrogenous wastes and creatinine. Continuous haemodiafiltration (HDF) or haemofiltration (HF) are commonly used renal replacement therapies for people with AKI. Buffered dialysates and solutions used in HDF or HF have varying effects on acid-base physiology and several electrolytes. The benefits and harms of bicarbonate- versus lactate-buffered HDF or HF solutions for treating patients with AKI remain unclear. To assess the benefits and harms of bicarbonate- versus lactate-buffered solutions for HDF or HF for treating people with AKI. We searched the Cochrane Renal Group's Specialised Register to 6 January 2015 through contact with the Trials' Search Co-ordinator using search terms relevant to this review. We also searched the Chinese Biomedical Literature Database. All randomised controlled trials (RCT) and quasi-RCTs that reported comparisons of bicarbonate-buffered solutions with lactate-buffered solutions for AKI were selected for inclusion irrespective of publication status or language. Two authors independently assessed titles and abstracts, and where necessary the full text of studies, to determine which satisfied our inclusion criteria. Data were extracted by two authors who independently assessed studies for eligibility and quality using a standardised data extraction form. Methodological quality was assessed using the Cochrane risk of bias tool. Results were expressed as risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI). We identified four studies (171 patients) that met our inclusion criteria. Overall, study quality was suboptimal. There were significant reporting omissions related to methodological issues and potential harms. Outcome measures were not defined or reported adequately. The studies were small and lacked follow-up phases.Serum lactate levels were significantly lower in patients treated with bicarbonate-buffered solutions (4 studies, 171 participants: MD -1.09 mmol/L, 95% CI -1.30 to -0.87; I(2) = 0%). There were no differences in mortality (3 studies, 163 participants: RR 0.76, 95% CI 0.50 to 1.15; I(2) = 0%); serum bicarbonate levels (3 studies, 163 participants: MD 0.27 mmol/L, 95% CI -1.45 to 1.99; I(2) = 78%), serum creatinine (2 studies, 137 participants: MD -22.81 µmol/L, 95% CI -129.61 to 83.99; I(2) = 73%), serum base excess (3 studies, 145 participants: MD 0.80, 95% CI -0.91 to 2.50; I(2) = 38%), serum pH (4 studies, 171 participants: MD 0.01, 95% CI -0.02 to 0.03; I(2) = 70%) or carbon dioxide partial pressure (3 studies, 151 participants: MD -1.04, 95% CI -3.84 to 1.76; I(2) = 83%). A single study reported fewer cardiovascular events (RR 0.39, 95% CI 0.20 to 0.79), higher mean arterial pressure (10.25 mm Hg, 95% CI 6.68 to 13.82) and less hypotensive events (RR 0.44, 95% CI 0.26 to 0.75) in patients receiving bicarbonate-buffered solutions. One study reported no significant difference in central venous pressure (MD 2.00 cm H2O, 95% CI -0.7 to, 4.77). Total length of hospital and ICU stay and relapse were not reported by any of the included studies. There were no significant different between bicarbonate- and lactate-buffered solutions for mortality, serum bicarbonate levels, serum creatinine, serum base excess, serum pH, carbon dioxide partial pressure, central venous pressure and serum electrolytes. Patients treated with bicarbonate-buffered solutions may experience fewer cardiovascular events, lower serum lactate levels, higher mean arterial pressure and less hypotensive events. With the exception of mortality, we were not able to assess the main primary outcomes of this review - length of time in ICU, total length of hospital stay and relapse.

Design of experiments reveals critical parameters for pilot-scale freeze-and-thaw processing of L-lactic dehydrogenase.

PubMed

Roessl, Ulrich; Humi, Sebastian; Leitgeb, Stefan; Nidetzky, Bernd

2015-09-01

Freezing constitutes an important unit operation of biotechnological protein production. Effects of freeze-and-thaw (F/T) process parameters on stability and other quality attributes of the protein product are usually not well understood. Here a design of experiments (DoE) approach was used to characterize the F/T behavior of L-lactic dehydrogenase (LDH) in a 700-mL pilot-scale freeze container equipped with internal temperature and pH probes. In 24-hour experiments, target temperature between -10 and -38°C most strongly affected LDH stability whereby enzyme activity was retained best at the highest temperature of -10°C. Cooling profile and liquid fill volume also had significant effects on LDH stability and affected the protein aggregation significantly. Parameters of the thawing phase had a comparably small effect on LDH stability. Experiments in which the standard sodium phosphate buffer was exchanged by Tris-HCl and the non-ionic surfactant Tween 80 was added to the protein solution showed that pH shift during freezing and protein surface exposure were the main factors responsible for LDH instability at the lower freeze temperatures. Collectively, evidence is presented that supports the use of DoE-based systematic analysis at pilot scale in the identification of F/T process parameters critical for protein stability and in the development of suitable process control strategies. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of amlodipine using terbium-sensitized luminescence in the presence of europium(III) as a co-luminescence reagent.

PubMed

Al-Kindy, Salma M Z; Al-Snedi, Abdalla; Suliman, Fakhr Eldin O; Al-Lawati, Haidar A J

2014-09-01

A sensitive time-resolved luminescence method for the determination of amlodipine (AM) in methanol and in aqueous solution is described. The method is based on the luminescence sensitization of terbium (Tb(3+) ) by formation of a ternary complex with AM in the presence of tri-n-octylphosphine oxide (TOPO) as co-ligand, dodecylbenzenesulfate as surfactant and europium ion as a co-luminescence reagent. The signal for Tb-AM-TOPO is monitored at λex  = 242 nm and λem  = 550 nm. Optimum conditions for the formation of the complex in aqueous system were 0.015 m Tris (hydroxylmethyl) amino methane buffer, pH 9.0, TOPO (1.0 × 10(-4) m), Eu(3+) (2.0 × 10(-7) m), dodecylbenzenesulfate (0.14%) and 6.0 × 10(-5) m of Tb(3+) , which allows the determination of 10-50 ppb of AM with a limit of detection of 1.2 ppb. The relative standard deviations of the method range between 0.1 and 0.2% indicated excellent reproducibility of the method. The proposed method was successfully applied for the assay of AM in pharmaceutical formulations and in plasma samples. Average recoveries of 98.5 ± 0.2% and 95.2 ± 0.2% were obtained for AM in tablet and plasma samples respectively. Copyright © 2013 John Wiley & Sons, Ltd.

Simultaneous determination of aliskiren and hydrochlorothiazide from their pharmaceutical preparations using a validated stability-indicating MEKC method.

PubMed

Sangoi, Maximiliano S; Wrasse-Sangoi, Micheli; Oliveira, Paulo R; Rolim, Clarice M B; Steppe, Martin

2011-08-01

A stability-indicating MEKC method was developed and validated for the simultaneous determination of aliskiren (ALI) and hydrochlorothiazide (HCTZ) in pharmaceutical formulations using ranitidine as an internal standard (IS). Optimal conditions for the separation of ALI, HCTZ and its major impurity chlorothiazide (CTZ), IS and degradation products were investigated. The method employed 47 mM Tris buffer and 47 mM anionic detergent SDS solution at pH 10.2 as the background electrolyte. MEKC method was performed on a fused-silica capillary (40 cm) at 28°C. Applied voltage was 26 kV (positive polarity) and photodiode array (PDA) detector was set at 217 nm. The method was validated in accordance with the ICH requirements. The method was linear over the concentration range of 5-100 and 60-1200 μg/mL for HCTZ and ALI, respectively (r(2) >0.9997). The stability-indicating capability of the method was established by enforced degradation studies combined with peak purity assessment using the PDA detection. Precision and accuracy evaluated by RSD were lower than 2%. The method proved to be robust by a fractional factorial design evaluation. The proposed MEKC method was successfully applied for the quantitative analysis of ALI and HCTZ both individually and in a combined dosage tablet formulation to support the quality control. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparative Evaluation of Small Molecular Additives and Their Effects on Peptide/Protein Identification.

PubMed

Gao, Jing; Zhong, Shaoyun; Zhou, Yanting; He, Han; Peng, Shuying; Zhu, Zhenyun; Liu, Xing; Zheng, Jing; Xu, Bin; Zhou, Hu

2017-06-06

Detergents and salts are widely used in lysis buffers to enhance protein extraction from biological samples, facilitating in-depth proteomic analysis. However, these detergents and salt additives must be efficiently removed from the digested samples prior to LC-MS/MS analysis to obtain high-quality mass spectra. Although filter-aided sample preparation (FASP), acetone precipitation (AP), followed by in-solution digestion, and strong cation exchange-based centrifugal proteomic reactors (CPRs) are commonly used for proteomic sample processing, little is known about their efficiencies at removing detergents and salt additives. In this study, we (i) developed an integrative workflow for the quantification of small molecular additives in proteomic samples, developing a multiple reaction monitoring (MRM)-based LC-MS approach for the quantification of six additives (i.e., Tris, urea, CHAPS, SDS, SDC, and Triton X-100) and (ii) systematically evaluated the relationships between the level of additive remaining in samples following sample processing and the number of peptides/proteins identified by mass spectrometry. Although FASP outperformed the other two methods, the results were complementary in terms of peptide/protein identification, as well as the GRAVY index and amino acid distributions. This is the first systematic and quantitative study of the effect of detergents and salt additives on protein identification. This MRM-based approach can be used for an unbiased evaluation of the performance of new sample preparation methods. Data are available via ProteomeXchange under identifier PXD005405.

Comparative measurement of cyanide and paraquat mitochondrial toxicity using two different mitochondrial toxicity assays.

PubMed

Mohammadi-Bardbori, Afshin; Ghazi-Khansari, Mahmoud

2007-01-01

ABSTRACT Cyanide (KCN) and paraquat (PQ) are very toxic to mitochondria. In this study the toxicity of KCN and PQ in the isolated rat liver mitochondria was determined using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay and JG-B (Janus green B) assay by multiwell scanning spectrophotometry. JG-B was used not only for the vital staining of mitochondria, but also for the mitochondrial viability assay and was compared to the MTT assay. The rat liver mitochondria were first isolated by centrifuge in a mixture of 0.25 M saccharose solution and 0.05 M Tris buffer. Various concentrations of paraquat (0.001 to 100 mM) and KCN (0.0001 to 100 M) on the mitochondria isolated from the liver were investigated. The 50% lethal concentration of toxins were found for PQ (4.45 +/- 0.02, 4.96 +/- 0.01) and KCN (0.22 +/- 0.02, 0.49 +/- 0.02), as determined by these assays ( JG-B and MTT, respectively ). Significant correlations were also observed among the two methods with a 95% coefficient interval (r(2) = 0.84, p < 0.001; r(2) = 0.91, p < 0.001; PQ and KCN, respectively). These results suggest that both methods are reliable and are comparable for determining the mitochondrial assay. It is concluded that the JG-B assay may be preferable to the MTT assay because of its simplicity, low cost, sensitivity, and objectivity; in addition, this method is not time dependent.

Molecular spectroscopic studies on the interaction of ferulic acid with calf thymus DNA.

PubMed

Zhang, Shufang; Sun, Xuejun; Qu, Fengli; Kong, Rongmei

2013-08-01

The interaction between ferulic acid and calf thymus deoxyribonucleic acid (ctDNA) under physiological conditions (Tris-HCl buffer solutions, pH 7.4) was investigated by UV-Vis spectroscopy, fluorescence spectroscopy, DNA melting techniques, and viscosity measurements. Results indicated that a complex of ferulic acid with ctDNA was formed with a binding constant of K(290K)=7.60×10(4) L mol(-1) and K(310K)=4.90×10(4) L mol(-1). The thermodynamic parameters enthalpy change (ΔH°), entropy change (ΔS°) and Gibbs free energy (ΔG°) were calculated to be -1.69×10(4) J mol(-1), 35.36 J K(-1) mol(-1) and -2.79×10(4) J mol(-1) at 310 K, respectively. The acting forces between ferulic acid and DNA mainly included hydrophobic interaction and hydrogen bonds. Acridine orange displacement studies revealed that ferulic acid can substitute for AO probe in the AO-DNA complex which was indicative of intercalation binding. Thermal denaturation study suggested that the interaction of ferulic acid with DNA could result in the increase of the denaturation temperature, which indicated that the stabilization of the DNA helix was increased in the presence of ferulic acid. Spectroscopic techniques together with melting techniques and viscosity determination provided evidences of intercalation mode of binding for the interaction between ferulic acid and ctDNA. Copyright © 2013 Elsevier B.V. All rights reserved.

A gold nanoparticles-modified aptamer beacon for urinary adenosine detection based on structure-switching/fluorescence-"turning on" mechanism.

PubMed

Zhang, Jin-Quan; Wang, Yong-Sheng; Xue, Jin-Hua; He, Yan; Yang, Hui-Xian; Liang, Jun; Shi, Lin-Fei; Xiao, Xi-Lin

2012-11-01

A novel small molecule probe, aptamer beacon (AB), was introduced for adenosine (Ade) recognition and quantitative analysis. The Ade aptamer was engineered into an aptamer beacon by adding a gold nanoparticle-modified nucleotide sequence which is complementary to aptamer sequence (FDNA) at the 3'-end of FDNA. The fluorescence signal "turning on" was observed when AB was bound to Ade, which is attributed to a significant conformational change in AB from a FDNA/QDNA duplex to a FDNA-Ade complex. The Ade measurement was carried out in 20 mmol L(-1) Tris-HCl buffer solution of pH 7.4, ΔF signal linearly correlated with the concentration of Ade over the range of 2.0×10(-8) to 1.8×10(-6) mol L(-1). The limit of detection (LOD) for Ade is 6.0×10(-9) mol L(-1) with relative standard deviations (R.S.D) of 3.64-5.36%, and the recoveries were 98.6%, 100%, 102% (n=6), respectively. The present method has been successfully applied to determine Ade in human urine samples, and the obtained results were in good agreement with those obtained by the HPLC method. Our investigation shows that the unique properties of the AB could provide a promising potential for small molecules detection, and be benefit to extend the application of aptamer beacon technique. Copyright © 2012 Elsevier B.V. All rights reserved.

Mechanism of chloride-dependent release of Ca2+ in the sarcoplasmic reticulum of rabbit skeletal muscle.

PubMed Central

Sukhareva, M; Morrissette, J; Coronado, R

1994-01-01

We investigated the effect of Cl- on the Ca2+ permeability of rabbit skeletal muscle junctional sarcoplasmic reticulum (SR) using 45Ca2+ fluxes and single channel recordings. In 45Ca2+ efflux experiments, the lumen of the SR was passively loaded with solutions of 150 mM univalent salt containing 5 mM 45Ca2+. Release of 45Ca2+ was measured by rapid filtration in the presence of extravesicular 0.4-0.8 microM free Ca2+ and 150 mM of the same univalent salt loaded into the SR lumen. The rate of release was 5-10 times higher when the univalent salt equilibrated across the SR-contained Cl- (Tris-Cl, choline-Cl, KCl) instead of an organic anion or other halides (gluconate-, methanesulfonate-, acetate-, HEPES-, Br-, I-). Cations (K+, Tris+) could be interchanged without a significant effect on the release rate. To determine whether Cl- stimulated ryanodine receptors, we measured the stimulation of release by ATP (5 mM total) and caffeine (20 mM total) and the inhibition by Mg2+ (0.8 mM estimated free) in Cl(-)-free and Cl(-)-containing solutions. The effects of ATP, caffeine, and Mg2+ were the largest in K-gluconate and Tris-gluconate, intermediate in KCl, and notably poor or absent in choline-Cl and Tris-Cl. Procaine (10 mM) inhibited the caffeine-stimulated release measured in K-gluconate, whereas the Cl- channel blocker clofibric acid (10 mM) but not procaine inhibited the caffeine-insensitive release measured in choline-Cl. Ruthenium red (20 microM) inhibited release in all solutions. In SR fused to planar bilayers we identified a nonselective Cl- channel (PCl: PTris: PCa = 1:0.5:0.3) blocked by ruthenium red and clofibric acid but not by procaine. These conductive and pharmacological properties suggested the channel was likely to mediate Cl(-)-dependent SR Ca2+ release. The absence of a contribution of ryanodine receptors to the Cl(-)-dependent release were indicated by the lack of an effect of Cl- on the open probability of this channel, a complete block by procaine, and a stimulation rather than inhibition by clofibric acid. A plug model of Cl(-)-dependent release, whereby Cl- removed the inhibition of the nonselective channel by large anions, was formulated under the assumption that nonselective channels and ryanodine receptor channels operated separately from each other in the terminal cisternae. The remarkably large contribution of Cl- to the SR Ca2+ permeability suggested that nonselective Cl- channels may control the Ca2+ permeability of the SR in the resting muscle cell. Images FIGURE 8 FIGURE 13 PMID:7948689

Free flow cell electrophoresis using zwitterionic buffer

NASA Technical Reports Server (NTRS)

Rodkey, R. Scott

1990-01-01

Studies of a zwitterionic buffer formulated for cell electrophoresis were done using the McDonnell-Douglas Continuous Flow Electrophoresis System. Standard buffers were analyzed for their stability in the electrical field and the results showed that both buffers tested were inherently unstable. Further, titration studies showed that the standards buffers buffered poorly at the pH employed for electrophoresis. The zwitterionic buffer buffered well at its nominal pH and was shown to be stable in the electrical field. Comparative studies of the buffer with standard cell separation buffers using formalin fixed rabbit and goose red blood cells showed that the zwitterionic buffer gave better resolution of the fixed cells. Studies with viable hybridoma cells showed that buffer Q supported cell viability equal to Hank's Balanced Salt Solution and that hybridoma cells in different stages of the growth cycle demonstrated reproducible differences in electrophoretic mobility.

Highly sensitive and selective detection of Al(III) ions in aqueous buffered solution with fluorescent peptide-based sensor.

PubMed

In, Byunggyu; Hwang, Gi Won; Lee, Keun-Hyeung

2016-09-15

A fluorescent sensor based on a tripeptide (SerGluGlu) with a dansyl fluorophore detected selectively Al(III) among 16 metal ions in aqueous buffered solutions without any organic cosolvent. The peptide-based sensor showed a highly sensitive turn on response to aluminium ion with high binding affinity (1.84×10(4)M(-1)) in aqueous buffered solutions. The detection limit (230nM, 5.98ppb) of the peptide-based sensor was much lower than the maximum allowable level (7.41μM) of aluminium ions in drinking water demanded by EPA. The binding mode of the peptide sensor with aluminium ions was characterized using ESI mass spectrometry, NMR titration, and pH titration experiments. Copyright © 2016 Elsevier Ltd. All rights reserved.

Detoxification of Chemical Warfare Agents Using a Zr6 -Based Metal-Organic Framework/Polymer Mixture.

PubMed

Moon, Su-Young; Proussaloglou, Emmanuel; Peterson, Gregory W; DeCoste, Jared B; Hall, Morgan G; Howarth, Ashlee J; Hupp, Joseph T; Farha, Omar K

2016-10-10

Owing to their high surface area, periodic distribution of metal sites, and water stability, zirconium-based metal-organic frameworks (Zr 6 -MOFs) have shown promising activity for the hydrolysis of nerve agents GD and VX, as well as the simulant, dimethyl 4-nitrophenylphosphate (DMNP), in buffered solutions. A hurdle to using MOFs for this application is the current need for a buffer solution. Here the destruction of the simulant DMNP, as well as the chemical warfare agents (GD and VX) through hydrolysis using a MOF catalyst mixed with a non-volatile, water-insoluble, heterogeneous buffer is reported. The hydrolysis of the simulant and nerve agents in the presence of the heterogeneous buffer was fast and effective. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of ultra-trace formaldehyde in air using ammonium sulfate as derivatization reagent and capillary electrophoresis coupled with on-line electrochemiluminescence detection.

PubMed

Deng, Biyang; Liu, Yang; Yin, Huihui; Ning, Xi; Lu, Hua; Ye, Li; Xu, Quanxiu

2012-03-15

The reaction between formaldehyde and ammonium ion to produce hexamethylenetetramine is well known. The reaction conditions are very easily controlled in situ and the experiment operation is very simple. However, such derivatization reaction for trace formaldehyde determination using capillary electrophoresis (CE) electrochemiluminescence (ECL) has not been reported before. In this study, the application of ammoniun sulfate as derivatization reagent to in-situ determination of formaldehyde in air was reported. Based on ECL enhancement of tris(2,2'-bipyridyl)ruthenium(II) with hexamethylenetetramine, a novel approach for the determination of ultra-trace formaldehyde in air using CE coupled with on-line ECL of tris(2,2'-bipyridyl)ruthenium(II) has been developed. The parameters affecting separation and detection such as detection potential, concentration and pH of phosphate buffer, and electrokinetic voltage, were investigated. Under the optimal conditions, the linear concentration range of formaldehyde in air was from 0.48 μg/m(3) to 96 mg/m(3) (linear range covering 5 orders of magnitude). The limit of detection (3σ) was 0.15 μg/m(3). The relative standard deviations of peak height and migration time for six consecutive injection of 1 ng/mL formaldehyde derivative were 0.9% and 0.8%, respectively. The recoveries of formaldehyde in air were between 99.3% and 101%. Copyright © 2012 Elsevier B.V. All rights reserved.

Low-density Lipoprotein Improves Motility and Plasma Membrane Integrity of Cryopreserved Canine Epididymal Spermatozoa

PubMed Central

Prapaiwan, N.; Tharasanit, T.; Punjachaipornpol, S.; Yamtang, D.; Roongsitthichai, A.; Moonarmart, W.; Kaeoket, K.; Manee-in, S.

2016-01-01

Cryopreservation of caudal epididymal spermatozoa is an effective technique to conserve genetic potentials of superior dogs when it is not possible to collect ejaculated spermatozoa. Although hen egg yolk is commonly supplemented into the semen extender, active substances within the egg yolk which protect sperm against cryoinjury remain to be discovered. Among its compositions, low-density lipoprotein (LDL) has been reported to have a cryoprotective property for sperm cryopreservation. However, the effects of LDL on dog epididymal spermatozoa during cryopreservation have not yet been investigated. This study aimed to investigate the effects of LDL on epididymal spermatozoa quality following cryopreservation and thawing. After routine castration of 12 dogs, caudal epididymides from individuals were separated from the testes and cut into a few pieces in a Tris-buffer. Spermatozoa recovered from each sample were examined at once for sperm quality and divided into six groups of extender: no LDL, 20% egg yolk, 4%, 8%, 16%, and 24% LDL, before cryopreservation. The sperm aliquots were then equilibrated and conventionally frozen. After thawing, sperm motility, morphology, plasma membrane integrity, and acrosome integrity were evaluated. The results revealed that 4% LDL and 20% egg yolk yielded significantly higher sperm motility (57.69% and 52.69%, respectively, p<0.05) than other LDLs. In addition, 4% LDL yielded the significantly highest plasma membrane integrity (70.54%, p<0.05). In conclusion, the supplementation of 4% LDL in Tris-glucose extender could be applied for cryopreservation of canine epididymal spermatozoa. PMID:26954170

Low-density Lipoprotein Improves Motility and Plasma Membrane Integrity of Cryopreserved Canine Epididymal Spermatozoa.

PubMed

Prapaiwan, N; Tharasanit, T; Punjachaipornpol, S; Yamtang, D; Roongsitthichai, A; Moonarmart, W; Kaeoket, K; Manee-In, S

2016-05-01

Cryopreservation of caudal epididymal spermatozoa is an effective technique to conserve genetic potentials of superior dogs when it is not possible to collect ejaculated spermatozoa. Although hen egg yolk is commonly supplemented into the semen extender, active substances within the egg yolk which protect sperm against cryoinjury remain to be discovered. Among its compositions, low-density lipoprotein (LDL) has been reported to have a cryoprotective property for sperm cryopreservation. However, the effects of LDL on dog epididymal spermatozoa during cryopreservation have not yet been investigated. This study aimed to investigate the effects of LDL on epididymal spermatozoa quality following cryopreservation and thawing. After routine castration of 12 dogs, caudal epididymides from individuals were separated from the testes and cut into a few pieces in a Tris-buffer. Spermatozoa recovered from each sample were examined at once for sperm quality and divided into six groups of extender: no LDL, 20% egg yolk, 4%, 8%, 16%, and 24% LDL, before cryopreservation. The sperm aliquots were then equilibrated and conventionally frozen. After thawing, sperm motility, morphology, plasma membrane integrity, and acrosome integrity were evaluated. The results revealed that 4% LDL and 20% egg yolk yielded significantly higher sperm motility (57.69% and 52.69%, respectively, p<0.05) than other LDLs. In addition, 4% LDL yielded the significantly highest plasma membrane integrity (70.54%, p<0.05). In conclusion, the supplementation of 4% LDL in Tris-glucose extender could be applied for cryopreservation of canine epididymal spermatozoa.

Identification of the Gene for Scleroderma in the Tsk/2 Mouse Strain: Implications for Human Scleroderma Pathogenesis and Subset Distinctions

DTIC Science & Technology

2014-09-01

onto an 8% SDS gel. Proteins were transferred to a polyvinylidene fluoride membrane, blocked in 5% nonfat milk in Tris-buffered saline, probed with...fibrosis (shown to be expressed at high levels in Tsk2/+ skin and used as  a marker of fibrosis [3, 4]), we assessed both  protein  and mRNA levels in...fibroblasts that received DNA from a  plasmid containing a single allele of a single Col3a1 gene. In three independent experiments, COL1A1  protein   was

Cyclic perylene diimide: Selective ligand for tetraplex DNA binding over double stranded DNA.

PubMed

Vasimalla, Suresh; Sato, Shinobu; Takenaka, Fuminori; Kurose, Yui; Takenaka, Shigeori

2017-12-15

Synthesized cyclic perylene diimide, cPDI, showed the binding constant of 6.3 × 10 6  M -1 with binding number of n = 2 with TA-core as a tetraplex DNA in 50 mM Tris-HCl buffer (pH = 7.4) containing 100 mM KCl using Schatchard analysis and showed a higher preference for tetraplex DNA than for double stranded DNA with over 10 3 times. CD spectra showed that TA-core induced its antiparallel conformation upon addition of cPDI in the absence or presence of K + or Na + ions. The cPDI inhibits the telomerase activity with IC 50 of 0.3 µM using TRAP assay which is potential anti-cancer drug with low side effect. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enantioseparations of amino acids by capillary array electrophoresis with 532 nm laser induced fluorescence detection.

PubMed

Liu, Kaiying; Wang, Li

2013-06-21

Capillary array electrophoresis (CAE) is a promising technique for multiple enantiomeric separations. Carboxytetramethylrhodamine succinimidyl ester (TAMRA SE), a rhodamine-core fluorescent probe, has rarely been applied as an original precolumn derivatization reagent for chiral amino acid (AA) analysis so far. For these purposes, high-throughput enantiomeric separations of 12 TAMRA SE-AAs by a home-made 532 nm CAE-LIF scanner are presented. The effect of cyclodextrins (CDs) and a variety of organic modifiers was quickly investigated. Baseline separations were achieved in 100 mM Tris-borate buffer (pH 10.0) containing 2 mM β-CD and 10 mM hexamethylenediamine (HDA). Multiple determination of the enantiomeric excess (ee) in non-racemic mixtures of alanine is successfully presented. Copyright © 2013 Elsevier B.V. All rights reserved.

Erosion of water-based cements evaluated by volumetric and gravimetric methods.

PubMed

Nomoto, Rie; Uchida, Keiko; Momoi, Yasuko; McCabe, John F

2003-05-01

To compare the erosion of glass ionomer, zinc phosphate and polycarboxylate cements using volumetric and gravimetric methods. For the volumetric method, the eroded depth of cement placed in a cylindrical cavity in PMMA was measured using a dial gauge after immersion in an eroding solution. For the gravimetric method, the weight of the residue of a solution in which a cylindrical specimen had been immersed was measured. 0.02 M lactic acid solution (0.02 M acid) and 0.1 M lactic acid/sodium lactate buffer solution (0.1 M buffer) were used as eroding solutions. The pH of both solutions was 2.74 and the test period was 24 h. Ranking of eroded depth and weight of residue was polycarboxylate>zinc phosphate>glass ionomers. Differences in erosion were more clearly defined by differences in eroded depth than differences in weight of residue. In 0.02 M acid, the erosion of glass ionomer using the volumetric method was effected by the hygroscopic expansion. In 0.1 M buffer, the erosion for polycarboxylate and zinc phosphate using the volumetric method was much greater than that using the gravimetric method. This is explained by cryo-SEM images which show many holes in the surface of specimens after erosion. It appears that zinc oxide is dissolved leaving a spongy matrix which easily collapses under the force applied to the dial gauge during measurement. The volumetric method that employs eroded depth of cement using a 0.1 M buffer solution is able to quantify erosion and to make material comparisons.

In vitro embryo production in camel (Camelus dromedarius) from in vitro matured oocytes fertilized with epididymal spermatozoa stored at 4 degrees C.

PubMed

Wani, N A

2009-03-01

Experiments were conducted to study the effect of storing epididymal spermatozoa, in tris-tes- and tris-lactose egg yolk extenders, on their fertilizing ability and subsequent in vitro embryo development. Ovaries and testes were collected from a local slaughterhouse in normal saline solution (NSS) at 37 degrees C and on ice (0-1 degrees C), respectively. Cumulus oocyte complexes (COCs) aspirated from the follicles were randomly distributed to 4-well culture plates (20-25COCs/well) containing 500 microL of maturation medium and cultured at 38.5 degrees C in an atmosphere of 5% CO(2) in air for 36 h. Spermatozoa were collected from the cauda epididymides in syringes containing 2-3 mL of either tris-tes- or tris-lactose egg yolk extender. They were cooled down slowly and stored at refrigeration (4 degrees C) temperature. The spermatozoa were evaluated for motility and used for IVF of IVM oocytes on the day of collection and after 2, 4, 6 and 8 days of storage. On the day of IVF, spermatozoa were prepared by the swim up technique and both spermatozoa and oocytes were co-incubated at 38.5 degrees C in a humidified atmosphere of 5% CO(2) in air for 15-16 h. Presumptive zygotes were either fixed and stained with Hoechst 33342 for evaluation of fertilization or were cultured in 500 microL of the culture medium at 38.5 degrees C in an atmosphere of 5% CO(2), 5% O(2) and 90% N(2) in air. There was no significant difference (P>0.05) in the proportion of oocytes fertilized with spermatozoa stored in either of the two extenders for up to 8 days. The proportion of oocytes that cleaved (43-60%) and those that developed to blastocysts (14-21%) did not show any difference (P>0.05) either, when spermatozoa from different days of storage were used. First cleavage was observed as early as 16 h after IVF, early blastocysts had developed by day 4, expanded blastocysts after day 5 and hatching of blastocysts started after day 6 of culture. It may be concluded that dromedary epididymal spermatozoa survive in storage for at least 8 days in tris-lactose- and tris-tes egg yolk diluents at 4 degrees C. These spermatozoa maintain fertilizing ability and may be suitable for use in IVF and other assisted reproductive procedures.

Reaction of 2-acetylaminofluorene-N-sulfate with RNA and glutathione: evidence for the generation of two reactive intermediates with different reactivities towards RNA and glutathione.

PubMed

van den Goorbergh, J A; Meerman, J H; de Wit, H; Mulder, G J

1985-11-01

The sulfate ester of N-hydroxy-2-acetylaminofluorene (AAF-N-sulfate) is one of the reactive intermediates of this carcinogen. This ester breaks down spontaneously to a very reactive nitrenium ion, which reacts with nucleophilic groups in protein, DNA, RNA and glutathione (GSH). Reactions involving the nitrenium ion with several nucleophiles under various conditions were studied. The adduct formation to RNA was much higher in Tris-HCI buffer than in phosphate buffer (at pH 7.4), while adduct formation to deoxy-guanosine monomers was the same in both buffers. The presence of 150 mM KCI had the same decreasing effect in both cases. Ionic strength effects may be involved in these phenomena. GSH decreased RNA adduct formation by 20-45%, while other thiols were much more effective. On the other hand, RNA did not decrease the formation of GSH conjugates from AAF-N-sulfate. The decrease in RNA adduct formation by thiols corresponded with an increase in the formation of 2-acetylaminofluorene (AAF) from AAF-N-sulfate, while no N-hydroxy-AAF was formed. These results suggest that two independent reactive intermediates are formed from AAF-N-sulfate, with different reactivities towards RNA and glutathione. Possibly these intermediates are the 'hard' triplet state nitrenium ion and the 'soft' singlet state nitrenium ion. Cysteine, cysteamine and penicillamine were most effective in the inhibition of RNA adduct formation; the extent of inhibition correlated with the extent of AAF formation. The mechanisms involved are discussed.

Continuous processing of recombinant proteins: integration of refolding and purification using simulated moving bed size-exclusion chromatography with buffer recycling.

PubMed

Wellhoefer, Martin; Sprinzl, Wolfgang; Hahn, Rainer; Jungbauer, Alois

2014-04-11

Continuous processing of recombinant proteins was accomplished by combining continuous matrix-assisted refolding and purification by tandem simulated moving bed (SMB) size-exclusion chromatography (SEC). Recombinant proteins, N(pro) fusion proteins from inclusion bodies were dissolved with NaOH and refolded in the SMB system with a closed-loop set-up with refolding buffer as the desorbent buffer and buffer recycling of the refolding buffer of the raffinate by tangential flow filtration. For further purification of the refolded proteins, a second SMB operation also based on SEC was added. The whole system could be operated isocratically with refolding buffer as the desorbent buffer, and buffer recycling could also be applied in the purification step. Thus, a significant reduction in buffer consumption was achieved. The system was evaluated with two proteins, the N(pro) fusion pep6His and N(pro) fusion MCP-1. Refolding solution, which contained residual N(pro) fusion peptide, the cleaved autoprotease N(pro), and the cleaved target peptide was used as feed solution. Full separation of the cleaved target peptide from residual proteins was achieved at a purity and recovery in the raffinate and extract, respectively, of approximately 100%. In addition, more than 99% of the refolding buffer of the raffinate was recycled. A comparison of throughput, productivity, and buffer consumption of the integrated continuous process with two batch processes demonstrated that up to 60-fold higher throughput, up to 180-fold higher productivity, and at least 28-fold lower buffer consumption can be obtained by the integrated continuous process, which compensates for the higher complexity. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis, structure and photoluminescence of (PLAGH){sub 2}[ZnCl{sub 4}] and comparative analysis of photoluminescence properties with tris(2,2′-bipyridine)ruthenium(II)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Radanović, Mirjana M.; Jelić, Miodrag G., E-mail: jelicmgm@uns.ac.rs; Romčević, Nebojša Ž.

Highlights: • New zinc(II) complex with pyridoxalaminoguanidine was synthesized. • The enhancement of the photoluminescence due to the compound formation was achieved. • Very high photoluminescence of Zn(II) compound was noticed. • Comparative analysis of photoluminescence with tris(2,2′-bipyridine) ruthenium(II) was provided. - Abstract: The first compound of zinc(II) containing pyridoxalaminoguanidine has been synthesized and characterized by elemental analysis, infrared spectra, conductometric measurements and X-ray crystallography. Single crystals of the compound were obtained in the reaction of methanolic solution of zinc(II) chloride and pyridoxalaminoguanidine hydrochloride. In this compound the coordination of chelate ligand is absent and tetrachlorido complex of zinc(II) withmore » pyridoxalaminuguanidinium cation as contraion is obtained. Photoluminescence spectra were measured. Lorentzian multipeak technique was used to determine peak wavelengths and their intensities. Photoluminescence spectroscopy upon 325, 488 and 514 nm laser excitation light was used to obtain results. This novel compound of zinc(II) was compared to the well-known organic light emitting diode material—ruthenium(II) complex with bypiridine i.e., tris(2,2′-bipyridine)ruthenium(II), under the same circumstances and the identical experimental setup. A scheme of energy levels and transitions is proposed to explain the obtained experimental results.« less

Vermiculite's strong buffer capacity renders it unsuitable for studies of acidity on soybean (Glycine max L.) nodulation and growth.

PubMed

Indrasumunar, Arief; Gresshoff, Peter M

2013-11-14

Vermiculite is the most common soil-free growing substrate used for plants in horticultural and scientific studies due to its high water holding capacity. However, some studies are not suitable to be conducted in it. The described experiments aimed to test the suitability of vermiculite to study the effect of acidity on nodulation and growth of soybean (Glycine max L.). Two different nutrient solutions (Broughton & Dilworth, and modified Herridge nutrient solutions) with or without MES buffer addition were used to irrigate soybean grown on vermiculite growth substrates. The pH of nutrient solutions was adjusted to either pH 4.0 or 7.0 prior its use. The nodulation and vegetative growth of soybean plants were assessed at 3 and 4 weeks after inoculation. The unsuitability of presumably inert vermiculite as a physical plant growth substrate for studying the effects of acidity on soybean nodulation and plant growth was illustrated. Nodulation and growth of soybean grown in vermiculite were not affected by irrigation with pH-adjusted nutrient solution either at pH 4.0 or 7.0. This was reasonably caused by the ability of vermiculite to neutralise (buffer) the pH of the supplied nutrient solution (pH 2.0-7.0). Due to its buffering capacity, vermiculite cannot be used as growth support to study the effect of acidity on nodulation and plant growth.

Titanium (III) cation selective electrode based on synthesized tris(2pyridyl) methylamine ionophore and its application in water samples

NASA Astrophysics Data System (ADS)

Rezayi, Majid; Karazhian, Reza; Abdollahi, Yadollah; Narimani, Leila; Sany, Seyedeh Belin Tavakoly; Ahmadzadeh, Saeid; Alias, Yatimah

2014-04-01

The introduction of low detection limit ion selective electrodes (ISEs) may well pave the way for the determination of trace targets of cationic compounds. This research focuses on the detection of titanium (III) cation using a new PVC-membrane sensor based on synthesized tris(2pyridyl) methylamine (tpm) ionophore. The application and validation of the proposed sensor was done using potentiometric titration, inductively coupled plasma atomic emission spectrometry (ICP-AES), and atomic absorption spectrometry (AAS). The membrane sensor exhibited a Nernstian response to the titanium (III) cation over a concentration range of 1.0 × 10-6-1.0 × 10-2 M and pH range from 1-2.5. The Nernstian slope, the lower of detection (LOD), and the response time (t95%) of the proposed sensor were 29.17 +/- 0.24 mV/dec, 7.9 × 10-7 M, and 20 s, respectively. The direct determination of 4-39 μg/ml of titanium (III) standard solution showed an average recovery of 94.60 and a mean relative standard deviation of 1.8 at 100.0 μg/ml. Finally, the utilization of the electrodes as end-point indicators for potentiometric titration with EDTA solutions for titanium (III) sensor was successfully carried out.

A gallium complex with a new tripodal tris-hydroxypyridinone for potential nuclear diagnostic imaging: solution and in vivo studies of 67Ga-labeled species.

PubMed

Chaves, Sílvia; Mendonça, Ana C; Marques, Sérgio M; Prata, M Isabel; Santos, Ana C; Martins, André F; Geraldes, Carlos F G C; Santos, M Amélia

2011-01-01

The gallium(III) complex of a new tripodal 3-hydroxy-4-pyridinone (3,4-HP) chelator has been studied in terms of its physico-chemical and in vivo properties aimed at potential application as probe for nuclear imaging. In particular, based on spectrophotometric titrations, the hexa-coordinated (1:1) gallium complex appeared as the major species in a wide physiological acid-neutral pH range and its high stability (pGa=27.5) should avoid drug-induced toxicity resulting from Ga(III) accumulation in tissues due to processes of transmetallation with endogenenous ligands or demetallation. A multinuclear ((1)H and (71)Ga) NMR study gave some insights into the structure and dynamics of the gallium(III) chelate in solution, which are consistent with the tris-(3,4-HP) coordination and an eventual pseudo-octahedral geometry. Biodistribution and scintigraphic studies of the (67)Ga(III) labelled chelate, performed in Wistar rats, confirmed the in vivo stability of the radiolabelled complex, its non interaction with blood proteins and its quick renal clearance. These results indicate good perspectives for potential application of extrafunctionalized analogues in radiodiagnostic techniques. Copyright © 2010 Elsevier Inc. All rights reserved.

Tetragonal Chicken Egg White Lysozyme Solubility in Sodium Chloride Solutions

NASA Technical Reports Server (NTRS)

Forsythe, Elizabeth L.; Judge, Russell A.; Pusey, Marc L.

1998-01-01

The solubility of chicken egg white lysozyme, crystallized in the tetragonal form was measured in sodium chloride solutions from 1.6 to 30.7 C, using a miniature column solubility apparatus. Sodium chloride solution concentrations ranged from 1 to 7% (w/v). The solutions were buffered with 0.1 M sodium acetate buffer with the solubility being measured at pH values in 0.2 pH unit increments in the range pH 4.0 to 5.4, with data also included at pH 4.5. Lysozyme solubility was found to increase with increases in temperature and decreasing salt concentration. Solution pH has a varied and unpredictable effect on solubility.

Ultrasonic spray coating polymer and small molecular organic film for organic light-emitting devices.

PubMed

Liu, Shihao; Zhang, Xiang; Zhang, Letian; Xie, Wenfa

2016-11-22

Ultrasonic spray coating process (USCP) with high material -utilization, low manufacture costs and compatibility to streamline production has been attractive in researches on photoelectric devices. However, surface tension exists in the solvent is still a huge obstacle to realize smooth organic film for organic light emitting devices (OLEDs) by USCP. Here, high quality polymer anode buffer layer and small molecular emitting layer are successfully realized through USCP by introducing extra-low surface tension diluent and surface tension control method. The introduction of low surface tension methyl alcohol is beneficial to the formation of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) films and brings obvious phase separation and improved conductivity to PEDOT:PSS film. Besides, a surface tension control method, in which new stable tension equilibrium is built at the border of wetting layer, is proposed to eliminate the effect of surface tension during the solvent evaporation stage of ultrasonic spray coating the film consists of 9,9-Spirobifluoren-2-yl-diphenyl-phosphine oxide doped with 10 wt% tris [2-(p -tolyl) pyridine] iridium (III). A smooth and homogenous small molecular emitting layer without wrinkles is successfully realized. The effectiveness of the ultrasonic spray coating polymer anode buffer layer and small molecular emitting layer are also proved by introducing them in OLEDs.

Flow cytometry reliability analysis and variations in sugarcane DNA content.

PubMed

Oliveira, A C L; Pasqual, M; Bruzi, A T; Pio, L A S; Mendonça, P M S; Soares, J D R

2015-06-29

The aim of this study was to evaluate the reliability of flow cytometry analysis and the use of this technique to differentiate species and varieties of sugarcane (Saccharum spp) according to their relative DNA content. We analyzed 16 varieties and three species belonging to this genus. To determine a reliable protocol, we evaluated three extraction buffers (LB01, Marie, and Tris·MgCl2), the presence and absence of RNase, six doses of propidium iodide (10, 15, 20, 25, and 30 μg), four periods of exposure to propidium iodide (0, 5, 10, and 20 min), and seven external reference standards (peas, beans, corn, radish, rye, soybean, and tomato) with reference to the coefficient of variation and the DNA content. For statistical analyses, we used the programs Sisvar(®) and Xlstat(®). We recommend using the Marie extraction buffer and at least 15 μg propidium iodide. The samples should not be analyzed immediately after the addition of propidium iodide. The use of RNase is optional, and tomato should be used as an external reference standard. The results show that sugarcane has a variable genome size (8.42 to 12.12 pg/2C) and the individuals analyzed could be separated into four groups according to their DNA content with relative equality in the genome sizes of the commercial varieties.

Ultrasonic spray coating polymer and small molecular organic film for organic light-emitting devices

NASA Astrophysics Data System (ADS)

Liu, Shihao; Zhang, Xiang; Zhang, Letian; Xie, Wenfa

2016-11-01

Ultrasonic spray coating process (USCP) with high material -utilization, low manufacture costs and compatibility to streamline production has been attractive in researches on photoelectric devices. However, surface tension exists in the solvent is still a huge obstacle to realize smooth organic film for organic light emitting devices (OLEDs) by USCP. Here, high quality polymer anode buffer layer and small molecular emitting layer are successfully realized through USCP by introducing extra-low surface tension diluent and surface tension control method. The introduction of low surface tension methyl alcohol is beneficial to the formation of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) films and brings obvious phase separation and improved conductivity to PEDOT:PSS film. Besides, a surface tension control method, in which new stable tension equilibrium is built at the border of wetting layer, is proposed to eliminate the effect of surface tension during the solvent evaporation stage of ultrasonic spray coating the film consists of 9,9-Spirobifluoren-2-yl-diphenyl-phosphine oxide doped with 10 wt% tris [2-(p -tolyl) pyridine] iridium (III). A smooth and homogenous small molecular emitting layer without wrinkles is successfully realized. The effectiveness of the ultrasonic spray coating polymer anode buffer layer and small molecular emitting layer are also proved by introducing them in OLEDs.

Purification, crystallization and preliminary X-ray diffraction analysis of the carbohydrate-binding region of the Streptococcus gordonii adhesin GspB

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pyburn, Tasia M.; Yankovskaya, Victoria; Bensing, Barbara A.

2012-07-11

The carbohydrate-binding region of the bacterial adhesin GspB from Streptococcus gordonii strain M99 (GspB{sub BR}) was expressed in Escherichia coli and purified using affinity and size-exclusion chromatography. Separate sparse-matrix screening of GspB{sub BR} buffered in either 20 mM Tris pH 7.4 or 20 mM HEPES pH 7.5 resulted in different crystallographic behavior such that different precipitants, salts and additives supported crystallization of GspB{sub BR} in each buffer. While both sets of conditions supported crystal growth in space group P2{sub 1}2{sub 1}2{sub 1}, the crystals had distinct unit-cell parameters of a = 33.3, b = 86.7, c = 117.9 {angstrom} formore » crystal form 1 and a = 34.6, b = 98.3, c = 99.0 {angstrom} for crystal form 2. Additive screening improved the crystals grown in both conditions such that diffraction extended to beyond 2 {angstrom} resolution. A complete data set has been collected to 1.3 {angstrom} resolution with an overall R{sub merge} value of 0.04 and an R{sub merge} value of 0.33 in the highest resolution shell.« less

Repeated-batch operation of immobilized β-galactosidase inclusion bodies-containing Escherichia coli cell reactor for lactose hydrolysis.

PubMed

Yeon, Ji-Hyeon; Jung, Kyung-Hwan

2011-09-01

In this study, we investigated the performance of an immobilized β-galactosidase inclusion bodies-containing Escherichia coli cell reactor, where the cells were immobilized in alginate beads, which were then used in repeated-batch operations for the hydrolysis of o-nitrophenyl-β-D-galactoside or lactose over the long-term. In particular, in the Tris buffer system, disintegration of the alginate beads was not observed during the operation, which was observed for the phosphate buffer system. The o-nitrophenyl-β-D-galactoside hydrolysis was operated successfully up to about 80 h, and the runs were successfully repeated at least eight times. In addition, hydrolysis of lactose was successfully carried out up to 240 h. Using Western blotting analyses, it was verified that the beta-galactosidase inclusion bodies were sustained in the alginate beads during the repeated-batch operations. Consequently, we experimentally verified that β-galactosidase inclusion bodies-containing Escherichia coli cells could be used in a repeated-batch reactor as a biocatalyst for the hydrolysis of o-nitrophenyl-β-D-galactoside or lactose. It is probable that this approach can be applied to enzymatic synthesis reactions for other biotechnology applications, particularly reactions that require long-term and stable operation.

Performance optimization in electric field gradient focusing.

PubMed

Sun, Xuefei; Farnsworth, Paul B; Tolley, H Dennis; Warnick, Karl F; Woolley, Adam T; Lee, Milton L

2009-01-02

Electric field gradient focusing (EFGF) is a technique used to simultaneously separate and concentrate biomacromolecules, such as proteins, based on the opposing forces of an electric field gradient and a hydrodynamic flow. Recently, we reported EFGF devices fabricated completely from copolymers functionalized with poly(ethylene glycol), which display excellent resistance to protein adsorption. However, the previous devices did not provide the predicted linear electric field gradient and stable current. To improve performance, Tris-HCl buffer that was previously doped in the hydrogel was replaced with a phosphate buffer containing a salt (i.e., potassium chloride, KCl) with high mobility ions. The new devices exhibited stable current, good reproducibility, and a linear electric field distribution in agreement with the shaped gradient region design due to improved ion transport in the hydrogel. The field gradient was calculated based on theory to be approximately 5.76 V/cm(2) for R-phycoerythrin when the applied voltage was 500 V. The effect of EFGF separation channel dimensions was also investigated; a narrower focused band was achieved in a smaller diameter channel. The relationship between the bandwidth and channel diameter is consistent with theory. Three model proteins were resolved in an EFGF channel of this design. The improved device demonstrated 14,000-fold concentration of a protein sample (from 2 ng/mL to 27 microg/mL).

Influence of some mononucleotides and their corresponding nucleosides on the metabolism of carbohydrates in the isolated rat diaphragm muscle

PubMed Central

Beloff-Chain, Anne; Betto, P.; Bleszynski, W.; Catanzaro, Raffaella; Chain, E. B.; Dmitrovskii, A. A.; Longinotti, L.; Pocchiari, F.

1965-01-01

1. The influence of ATP on glucose metabolism was studied in the isolated rat diaphragm; it was shown that ATP increases the oxidation of glucose and the aerobic conversion of glucose into lactate, whereas it decreases glycogen synthesis. There was no influence of ATP on the anaerobic formation of lactate from glucose. 2. A maximum effect of ATP on the oxidation of glucose (about 160% increase) was obtained in the presence of 10mm-ATP; in the presence of 2mm-ATP the effect was about 65%, and was approximately constant from 10 to 90min. incubation period. 3. In a phosphate-free tris-buffered medium the oxidation of glucose was considerably decreased, but the percentage stimulation by ATP was about the same as in a phosphate-buffered medium. 4. ATP was shown to increase the oxidation of fructose, glucose 6-phosphate, glucose 1-phosphate, fructose 1,6-diphosphate and, to a much smaller extent, pyruvate. 5. ADP stimulated the oxidation of glucose to the same extent as ATP at a concentration of 2mm and the effect with AMP was only slightly less; IMP and adenosine had only a small stimulatory effect at this concentration, whereas inosine had no effect. PMID:16749165

Ultrasonic spray coating polymer and small molecular organic film for organic light-emitting devices

PubMed Central

Liu, Shihao; Zhang, Xiang; Zhang, Letian; Xie, Wenfa

2016-01-01

Ultrasonic spray coating process (USCP) with high material -utilization, low manufacture costs and compatibility to streamline production has been attractive in researches on photoelectric devices. However, surface tension exists in the solvent is still a huge obstacle to realize smooth organic film for organic light emitting devices (OLEDs) by USCP. Here, high quality polymer anode buffer layer and small molecular emitting layer are successfully realized through USCP by introducing extra-low surface tension diluent and surface tension control method. The introduction of low surface tension methyl alcohol is beneficial to the formation of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) films and brings obvious phase separation and improved conductivity to PEDOT:PSS film. Besides, a surface tension control method, in which new stable tension equilibrium is built at the border of wetting layer, is proposed to eliminate the effect of surface tension during the solvent evaporation stage of ultrasonic spray coating the film consists of 9,9-Spirobifluoren-2-yl-diphenyl-phosphine oxide doped with 10 wt% tris [2-(p -tolyl) pyridine] iridium (III). A smooth and homogenous small molecular emitting layer without wrinkles is successfully realized. The effectiveness of the ultrasonic spray coating polymer anode buffer layer and small molecular emitting layer are also proved by introducing them in OLEDs. PMID:27874030

Simply enhancing throughput of free-flow electrophoresis via organic-aqueous environment for purification of weak polarity solute of phenazine-1-carboxylic acid in fermentation of Pseudomonas sp. M18.

PubMed

Yang, Jing-Hua; Shao, Jing; Wang, Hou-Yu; Dong, Jing-Yu; Fan, Liu-Yin; Cao, Cheng-Xi; Xu, Yu-Quan

2012-09-01

Herein, a simple novel free-flow electrophoresis (FFE) method was developed via introduction of organic solvent into the electrolyte system, increasing the solute solubility and throughput of the sample. As a proof of concept, phenazine-1-carboxylic acid (PCA) from Pseudomonas sp. M18 was selected as a model solute for the demonstration on feasibility of novel FFE method on account of its faint solubility in aqueous circumstance. In the developed method, the organic solvent was added into not only the sample buffer to improve the solubility of the solute, but also the background buffer to construct a uniform aqueous-organic circumstance. These factors of organic solvent percentage and types as well as pH value of background buffer were investigated for the purification of PCA in the FFE device via CE. The experiments revealed that the percentage and the types of organic solvent exerted major influence on the purification of PCA. Under the optimized conditions (30 mM phosphate buffer in 60:40 (v/v) water-methanol at an apparent pH 7.0, 3.26 mL/min background flux, 10-min residence time of injected sample, and 400 V), PCA could be continuously purified from its impurities. The flux of sample injection was 10.05 μL/min, and the recovery was up to 93.7%. An 11.9-fold improvement of throughput was found with a carrier buffer containing 40% (v/v) methanol, compared with the pure aqueous phase. The developed procedure is of evident significance for the purification of weak polarity solute via FFE. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced efficiency of inverted polymer solar cells by using solution-processed TiOx/CsOx cathode buffer layer.

PubMed

Zhou, Xiaodong; Fan, Xi; Sun, Xianke; Zhang, Yunli; Zhu, Ziqiang

2015-01-01

In this work, a double-buffer film of TiOx coated with CsOx (TiOx/CsOx) was solution prepared to be applied in poly(3-hexylthiophene):indene-C60 bisadduct (P3HT:ICBA) and P3HT:[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) inverted polymer solar cells (PSCs). Compared with TiOx films and CsOx films, the TiOx/CsOx double-buffer film exhibited a favorable energy-level alignment among TiOx, CsOx, and the electron acceptor of PCBM or ICBA a better surface morphology; and an enhanced wetting and adhesion property with a contact angle of 21.0°, leading to a higher electron mobility of 5.52 × 10(-3) cm(2) V(-1)·s(-1). Moreover, the P3HT:ICBA and P3HT:PCBM photovoltaic devices with the double-buffer film showed the best power conversion efficiency up to 5.65% and 3.76%, respectively. Our results not only present that the double-buffer film is superior than the single film of TiOx and CsOx, but also imply that the solution-processed film has a potential to be generally used in roll-to-roll processed organic photovoltaic devices.

Vein Graft Preservation Solutions, Patency, and Outcomes After Coronary Artery Bypass Graft Surgery

PubMed Central

Harskamp, Ralf E.; Alexander, John H.; Schulte, Phillip J.; Brophy, Colleen M.; Mack, Michael J.; Peterson, Eric D.; Williams, Judson B.; Gibson, C. Michael; Califf, Robert M.; Kouchoukos, Nicholas T.; Harrington, Robert A.; Ferguson, T. Bruce; Lopes, Renato D.

2015-01-01

IMPORTANCE In vitro and animal model data suggest that intraoperative preservation solutions may influence endothelial function and vein graft failure (VGF) after coronary artery bypass graft (CABG) surgery. Clinical studies to validate these findings are lacking. OBJECTIVE To evaluate the effect of vein graft preservation solutions on VGF and clinical outcomes in patients undergoing CABG surgery. DESIGN, SETTING, AND PARTICIPANTS Data from the Project of Ex-Vivo Vein Graft Engineering via Transfection IV (PREVENT IV) study, a phase 3, multicenter, randomized, double-blind, placebo-controlled trial that enrolled 3014 patients at 107 US sites from August 1, 2002, through October 22, 2003, were used. Eligibility criteria for the trial included CABG surgery for coronary artery disease with at least 2 planned vein grafts. INTERVENTIONS Preservation of vein grafts in saline, blood, or buffered saline solutions. MAIN OUTCOMES AND MEASURES One-year angiographic VGF and 5-year rates of death, myocardial infarction, and subsequent revascularization. RESULTS Most patients had grafts preserved in saline (1339 [44.4%]), followed by blood (971 [32.2%]) and buffered saline (507 [16.8%]). Baseline characteristics were similar among groups. One-year VGF rates were much lower in the buffered saline group than in the saline group (patient-level odds ratio [OR], 0.59 [95% CI, 0.45-0.78; P < .001]; graft-level OR, 0.63 [95% CI, 0.49-0.79; P < .001]) or the blood group (patient-level OR, 0.62 [95% CI, 0.46-0.83; P = .001]; graft-level OR, 0.63 [95% CI, 0.48-0.81; P < .001]). Use of buffered saline solution also tended to be associated with a lower 5-year risk for death, myocardial infarction, or subsequent revascularization compared with saline (hazard ratio, 0.81 [95% CI, 0.64-1.02; P = .08]) and blood (0.81 [0.63-1.03; P = .09]) solutions. CONCLUSIONS AND RELEVANCE Patients undergoing CABG whose vein grafts were preserved in a buffered saline solution had lower VGF rates and trends toward better long-term clinical outcomes compared with patients whose grafts were preserved in saline- or blood-based solutions. PMID:25073921

Ion sensitivity of large-area epitaxial graphene film on SiC substrate

NASA Astrophysics Data System (ADS)

Mitsuno, Takanori; Taniguchi, Yoshiaki; Ohno, Yasuhide; Nagase, Masao

2017-11-01

We investigated the intrinsic ion sensitivity of graphene field-effect transistors (FETs) fabricated by a resist-free stencil mask lithography process from a large-scale graphene film epitaxially grown on a SiC substrate. A pH-adjusted phosphate-buffered solution was used for the measurement to eliminate the interference of other ions on the graphene FET's ion sensitivity. The charge neutrality point shifted negligibly with changing pH for the pH-adjusted phosphate-buffered solution, whereas for the mixed buffer solution, it shifted toward the negative gate voltage owing to the decrease in the concentration of phthalate ions. This phenomenon is contrary to that observed in previous reports. Overall, our results indicate that the graphene film is intrinsically insensitive to ions except for those with functional groups that interact with the graphene surface.

Solution-processed MoS(x) as an efficient anode buffer layer in organic solar cells.

PubMed

Li, Xiaodong; Zhang, Wenjun; Wu, Yulei; Min, Chao; Fang, Junfeng

2013-09-25

We reported a facile solution-processed method to fabricate a MoSx anode buffer layer through thermal decomposition of (NH4)2MoS4. Organic solar cells (OSCs) based on in situ growth MoSx as the anode buffer layer showed impressive improvements, and the power conversion efficiency was higher than that of conventional PEDOT:PSS-based device. The MoSx films obtained at different temperatures and the corresponding device performance were systematically studied. The results indicated that both MoS3 and MoS2 were beneficial to the device performance. MoS3 could result in higher Voc, while MoS2 could lead to higher Jsc. Our results proved that, apart from MoO3, molybdenum sulfides and Mo(4+) were also promising candidates for the anode buffer materials in OSCs.

Calculated and measured [Ca(2+)] in buffers used to calibrate Ca(2+) macroelectrodes.

PubMed

McGuigan, John A S; Stumpff, Friederike

2013-05-01

The ionized concentration of calcium in physiological buffers ([Ca(2+)]) is normally calculated using either tabulated constants or software programs. To investigate the accuracy of such calculations, the [Ca(2+)] in EGTA [ethylene glycol-bis(β-aminoethylether)-N,N,N|,N|-tetraacetic acid], BAPTA [1,2-bis(o-aminophenoxy) ethane-N,N,N|,N|-tetraacetic acid], HEDTA [N-(2-hydroxyethyl)-ethylenediamine-N,N|,N|-triacetic acid], and NTA [N,N-bis(carboxymethyl)glycine] buffers was estimated using the ligand optimization method, and these measured values were compared with calculated values. All measurements overlapped in the pCa range of 3.51 (NTA) to 8.12 (EGTA). In all four buffer solutions, there was no correlation between measured and calculated values; the calculated values differed among themselves by factors varying from 1.3 (NTA) to 6.9 (EGTA). Independent measurements of EGTA purity and the apparent dissociation constants for HEDTA and NTA were not significantly different from the values estimated by the ligand optimization method, further substantiating the method. Using two calibration solutions of pCa 2.0 and 3.01 and seven buffers in the pCa range of 4.0-7.5, calibration of a Ca(2+) electrode over the pCa range of 2.0-7.5 became a routine procedure. It is proposed that such Ca(2+) calibration/buffer solutions be internationally defined and made commercially available to allow the precise measurement of [Ca(2+)] in biology. Copyright © 2013 Elsevier Inc. All rights reserved.

Study of buffer substrate and Arenga wood fiber size on hydroponic Kailan (Brassica alboglabra)

NASA Astrophysics Data System (ADS)

Harjoko, D.; Anggraheny, M. D.; Arniputri, R. B.

2018-03-01

Kailan is a kind of vegetable that has high economic value, however its prospect is not well developed. One of obstacles in Kailan cultivation is the limitation of fertile soil, that can be solved by using hydroponic substrate. Considering its amount and potential, the fiber waste of Arenga wood was selected as substrate candidate. For that, this research aims to study the growth and yield of Kailan with different soaking treatment using buffer solution and size of Arenga wood fiber in the hydroponic substrate. Research was conducted at Green House Laboratory, Faculty of Agriculture Sebelas Maret University Surakarta from February to May 2017. The treatments were soaking buffer solution with EC 1.2 mScm-1; 1.4 mScm-1; and 1.6 mScm-1 and the size of Arenga fiber <1 cm, 1-2 cm and 2-3 cm. In this experiment, sand media was used as control. Result show that, soaking in 1.6 mScm-1 EC buffer solution with Arenga fiber size lower than 3 cm gives higher root volume compared to other treatments combination.

Buffered hydrochloric acid: a modern method of treating metabolic alkalosis.

PubMed

Finkle, D; Dean, R E

1981-03-01

Twenty-one patients with metabolic alkalosis were treated successfully with intravenous hydrochloric acid (HCl) buffered in an amino acid solution (TPN). No complications of HCl were seen. TPN was used to meet energy needs and provide a buffering effect through the interaction of HCl and amino acids. Buffered HCl therapy should be considered as the initial treatment in patients with metabolic alkalosis associated with congestive heart failure, renal failure, hepatic failure, cerebral edema, or refractory metabolic alkalosis.

Buffer salt effects in off-line coupling of capillary electrophoresis and mass spectrometry.

PubMed

Marák, Jozef; Stanová, Andrea

2014-05-01

In this work, the impact of buffer salts/matrix effects on the signal in direct injection MS with an electrospray interface (DI-ESI-MS) following pITP fractionation of the sample was studied. A range of buffers frequently used in CE analyses (pH 3-10) was prepared containing 10, 50, and 90% v/v of ACN, respectively. The sets of calibration solutions of cetirizine (an antihistaminic drug with an amphiprotic character) within a 0.05-2.0 mg/L concentration range were prepared in different buffers. The greatest enhancements in the MS signal (in terms of change in the slope of the calibration line) were obtained for the beta-alanine buffer (pH 3.5) in positive ionization and for the borate buffer (pH 9.2) in negative ionization, respectively. The procedure was successfully applied to the analysis of buserelin (a peptidic drug). The slope of the calibration line for solutions containing the beta-alanine buffer with 50% of ACN was 4 times higher than for water or urine, respectively. This study clearly demonstrates that the buffer salt/matrix effects in an offline combination of pITP and DI-ESI-MS can also play a positive role, as they can enhance the signal in MS. A similar influence of the above effects can also be presumed in the CE techniques combined on-line with ESI-MS.

Advanced oxidation kinetics of aqueous tri alkyl phosphate flame retardants and plasticizers

PubMed Central

Watts, Michael J.; Linden, Karl G.

2009-01-01

Tri alkyl phosphate esters are a class of anthropogenic organics commonly found in surface waters of Europe and North America, due to their frequent application as flame retardants, plasticizers, and solvents. Four tri alkyl phosphate esters were evaluated to determine second-order rates of reaction with ultraviolet- and ozone-generated •OH in water. In competition with nitrobenzene in UV irradiated hydrogen peroxide solutions tris(2-butoxyethyl) phosphate (TBEP) was fastest to react with •OH (kOH,TBEP=1.03×1010 M-1s-1), followed sequentially by tributyl phosphate (TBP), tris(2-chloroethyl) phosphate (TCEP), and tris(2-chloroisopropyl) phosphate (TCPP) (kOH,TBEP=6.40×109, kOH,TBEP=5.60×108, & kOH,TBEP=1.98×10 M-1s-1). A two-stage process was used to test the validity of the determined kOH for TBEP and the fastest reacting halogenated alkyl phosphate, TCEP. First, •OH oxidation of TCEP and TBEP, in competition with nitrobenzene, was measured in ozonated hydrogen peroxide solutions. Applying multiple regression analysis, it was determined that the UV-H2O2 and O3-H2O2 data sets were statistically identical for each compound. The subsequent validated kOH were used to predict TCEP and TBEP photodegradation in neutral pH, model surface water after chemical oxidant addition and UV irradiation (up to 1000 mJ/cm2). The insignificant difference, between the predicted TBEP and TCEP photodegradation and a best-fit of the first-order exponential decay function to the observed TBEP and TCEP concentrations with increasing UV fluence, was further evidence of the validity of the determined kOH. TBEP oxidation rates were similar in the surface waters tested. Substantial TCEP oxidation in the model surface water required a significant increase in H2O2. PMID:19475974

[Study on stability of curcumine, demethoxycurcumin and bisdemethoxycurcumin].

PubMed

Han, Gang; Cui, Jing-jing; Bi, Rui; Zhao, Lin-lin; Zhang, Wei-guo

2008-11-01

To investigate the stability of curcumin, demethoxycurcumin and bisdemethoxycurcumin in different buffer solution. To determine concentration of curcumin by HPLC when added curcumin, demethoxycurcumin and bisdemethoxycurcumin into the buffer solution the equation of degradation was established. The sequence of stability are bisdemethoxycurcumin > or = demethoxycurcumin > or =curcumin at the same condition. The demethoxycurcumin can stabilize curcumin more strong than the others. The demethoxycurcumin is a nature stabilizing agent for curcumin.

Common stock solutions, buffers, and media.

PubMed

2001-05-01

This section describes the preparation of buffers and reagents used in this manual for cell culture, manipulation of tissue, and cell biological methods. Also discussed are special considerations for PCR experiments and for working with RNA.

Escherichia coli growth changes by the mediated effects after low-intensity electromagnetic irradiation of extremely high frequencies.

PubMed

Torgomyan, Heghine; Hovnanyan, Karlen; Trchounian, Armen

2013-04-01

Water is the major constituent of environmental medium and biological systems. The effects occurring in water as a result of low-intensity electromagnetic irradiation (EMI) in extremely high frequencies are supposed to be the primary mechanism to create conditions for biological responses. The EMI effects on Escherichia coli, after irradiation of their suspension, are most probably water-mediated. Indirect effects of EMI at 51.8, 53, 70.6, and 73 GHz frequencies on bacteria, through water, assay buffer (Tris-phosphate buffer with inorganic salts at low or moderate concentrations), or peptone growth medium were studied. The mediated effects of 70.6 and 73 GHz irradiated water, assay buffer, and growth medium on E. coli growth characteristics were insignificant. But the results were different for 51.8 and 53 GHz. EMI mediated effects on bacterial growth were clearly demonstrated. The effects were more strongly expressed with 53 GHz. Moreover, it was shown that 70.6 and 73 GHz similarly suppressed the cell growth after direct irradiation of E. coli in water or on solid medium. Interestingly, for 51.8 and 53 GHz the bacterial growth decreases after suspension irradiation was less, compared to the direct irradiation of bacteria on solid medium. Especially, it was also more expressed in case of 53 GHz. Also with electron microscopy, EMI-induced bacterial cell sizes and structure different changes were detected. In addition, the distinguished changes in surface tension, oxidation-reduction potential and pH of water, assay buffer, growth medium, and bacterial suspension were determined. They depended on EMI frequency used. The differences could be associated with the partial absorbance of EMI energy by the surrounding medium, which depends on a specific frequency. The results are crucial to understand biophysical mechanisms of EMI effects on bacteria.

Aseptic hydroponics to assess rhamnolipid-Cd and rhamnolipid-Zn bioavailability for sunflower (Helianthus annuus): a phytoextraction mechanism study.

PubMed

Wen, Jia; McLaughlin, Mike J; Stacey, Samuel P; Kirby, Jason K

2016-11-01

The availability of cadmium (Cd) and zinc (Zn) to sunflower (Helianthus annuus) was investigated in rhamnolipid- and ethylenediaminetetraacetic acid (EDTA)-buffered solutions in order to evaluate the influence of aqueous speciation of the metals on their uptake by the plant, in relation to predictions of uptake by the free ion activity model (FIAM). Free metal ion activity was estimated using the chemical equilibrium program MINTEQ or measured by Donnan dialysis. The uptake of Cd followed the FIAM for the EDTA-buffered solution at EDTA concentrations below 0.4 μM; for the rhamnolipid-buffered solution, the uptake of both metals in roots was not markedly affected by increasing rhamnolipid concentrations in solution. This suggests rhamnolipid enhanced metal accumulation in plant roots (per unit free metal in solution) possibly through formation and uptake of lipophilic complexes. The addition of normal Ca concentrations (low millimetre range) to the rhamnolipid uptake solutions reduced Cd accumulation in shoots by inhibiting Cd translocation, whereas it significantly increased Zn accumulation in shoots. This study confirms that although rhamnolipid could enhance accumulation of Cd in plants roots at low Ca supply, it is not suitable for Cd phytoextraction in contaminated soil environments where Ca concentrations in soil solution are orders of magnitude greater than those of Cd.

Fertility results using bovine semen cryopreserved with extenders based on egg yolk and soy bean extract.

PubMed

van Wagtendonk-de Leeuw, A M; Haring, R M; Kaal-Lansbergen, L M; den Daas, J H

2000-07-01

Semen extenders containing components such as egg yolk and skim milk are difficult to standardize and they introduce the risk of microbial contamination. A well-defined extender not originating from animal tissues would present a valuable contribution to the AI industry. We evaluated the fertility of bovine semen cryopreserved with 3 different extenders: 1) TRIS-Standard, prepared at 2 local AI laboratories, containing 20% (v/v) pasteurized egg yolk, 2) TRIS-Concentrate, prepared by adding 20% (v/v) pasteurized egg yolk and 1:5 (v/v) nonpyrogenic water, and 3) Biociphos Plus, a soybean extract containing extender, prepared by adding 1:5 nonpyrogenic water. Ejaculates of 4 Holstein bulls were split into 3 aliquots and cryopreserved with the 3 extenders. Prior to this study, the semen dose-response curve for each of the 4 bulls was developed in a field trial by freezing the semen and randomly distributing the straws throughout the Netherlands for insemination. Optimal semen doses were thus established to detect the effect of extenders on fertility, evaluated by 56-day non-return rate (NR56), and by the estimated conception rate and the calving rate, given a conception. We used the multiphasic model developed by Grossman et al. (7). A total of 22,246 first and second inseminations were recorded. The NR56 ranged among bulls from 67.0 to 70.1% for Tris-Standard, from 67.5 to 69.9% for Tris-Concentrate and from 60.2 to 66.7% for Biociphos Plus. No significant differences in NR56 were detected between Tris-Standard and Tris-Concentrate (P=0.54), whereas Biociphos Plus resulted in a significantly lower NR56 than Tris-Standard and Tris-Concentrate (P<0.05). Estimated conception rate was 72.1, 73.6 and 69.6% and estimated calving rate, given a conception was 80.6, 78.3 and 77.1 for Tris-Standard, Tris-Concentrate and Biociphos Plus, respectively. These results indicate that 1) semen extended with a custom made TRIS-Concentrate can be succesfully used in the field resulting in comparable fertility with Tris-Standard; 2) semen extended with Biociphos Plus results in a significant reduction in the NR56; 3) extender source may affect both conception rate and calving rate, given a conception, i.e., extrinsic and intrinsic sperm factors (4).

Aqueous photolysis of niclosamide

USGS Publications Warehouse

Graebing, P.W.; Chib, J.S.; Hubert, T.D.; Gingerich, W.H.

2004-01-01

The photodegradation of [14C]niclosamide was studied in sterile, pH 5, 7, and 9 buffered aqueous solutions under artificial sunlight at 25.0 A? 1.0 A?C. Photolysis in pH 5 buffer is 4.3 times faster than in pH 9 buffer and 1.5 times faster than in pH 7 buffer. In the dark controls, niclosamide degraded only in the pH 5 buffer. After 360 h of continuous irradiation in pH 9 buffer, the chromatographic pattern of the degradates was the same regardless of which ring contained the radiolabel. An HPLC method was developed that confirmed these degradates to be carbon dioxide and two- and four-carbon aliphatic acids formed by cleavage of both aromatic rings. Carbon dioxide was the major degradate, comprising 40% of the initial radioactivity in the 360 h samples from both labels. The other degradates formed were oxalic acid, maleic acid, glyoxylic acid, and glyoxal. In addition, in the chloronitroaniline-labeled irradiated test solution, 2-chloro-4-nitroaniline was observed and identified after 48 h of irradiation but was not detected thereafter. No other aromatic compounds were isolated or observed in either labeled test system.

Structure and optical properties of ZnO produced from microwave hydrothermal hydrolysis of tris(ethylenediamine)zinc nitrate complex

NASA Astrophysics Data System (ADS)

Mostafa, Nasser Y.; Heiba, Zein K.; Ibrahim, Mohamed M.

2015-01-01

ZnO powders were synthesized using a solution microwave hydrothermal hydrolysis process and tris(ethylenediamine)zinc nitrate {[Zn(en)3](NO3)2} (en = ethylenediamine) as a precursor. Hydrolysis of the precursor complex at different pH produced zinc oxide with a diversity of well-defined morphologies. The effect of hydrolysis pH values on the structural and optical properties has been explored using XRD, SEM, and UV-visible diffuse reflectance spectroscopy (DRS). At pH = 7.0, randomly dispersed rods were formed. Whereas flower-like morphologies were obtained by treating the complex precursor in water at pH = 10.0 and 12.0. The ZnO4 tetrahedrons are greatly affected by the pH value. The band gap decreased sharply with increasing the pH value from 7.0 to 10.0, then slightly decreased with further increasing the pH to 12.0. The relationship between band gap and both structure and surface defects of the samples is also discussed.

A theoretical study on the mechanistic highlights behind the Brønsted-acid dependent mer-fac isomerization of homoleptic carbenic iridium complexes for PhOLEDs.

PubMed

Setzer, Tobias; Lennartz, Christian; Dreuw, Andreas

2017-06-06

Recently, a successful Brønsted-acid mediated geometric isomerization of the meridional homoleptic carbenic iridium(iii) complexes tris-(N-phenyl,N-methyl-benzimidazol-2-yl)iridium(iii) (1) and tris-(N-phenyl,N-benzyl-benzimidazol-2-yl)iridium(iii) (2) into their facial form has been reported. In the present work the pronounced acid-dependency of this particular isomerization procedure is revisited and additional mechanistic pathways are taken into account. Moreover, the acid-induced material decomposition is addressed. All calculations are carried out using density functional theory (DFT) while the environmental effects in solution are accounted for by the COSMO-RS model. The simulated results clearly reveal the outstanding importance of the complex interplay between acid strength, coordinating power of the corresponding base and the steric influence of the ligand system in contrast to the plain calculation of minimum energy pathways for selected complexes. Eventually, general rules to enhance the material-specific reaction yields are provided.

A dynamic system for the simulation of fasting luminal pH-gradients using hydrogen carbonate buffers for dissolution testing of ionisable compounds.

PubMed

Garbacz, Grzegorz; Kołodziej, Bartosz; Koziolek, Mirko; Weitschies, Werner; Klein, Sandra

2014-01-23

The hydrogen carbonate buffer is considered as the most biorelevant buffer system for the simulation of intestinal conditions and covers the physiological pH range of the luminal fluids from pH 5.5 to about pH 8.4. The pH value of a hydrogen carbonate buffer is the result of a complex and dynamic interplay of the concentration of hydrogen carbonate ions, carbonic acid, the concentration of dissolved and solvated carbon dioxide and its partial pressure above the solution. The complex equilibrium between the different ions results in a thermodynamic instability of hydrogen carbonate solutions. In order to use hydrogen carbonate buffers with pH gradients in the physiological range and with the dynamics observed in vivo without changing the ionic strength of the solution, we developed a device (pHysio-grad®) that provides both acidification of the dissolution medium by microcomputer controlled carbon dioxide influx and alkalisation by degassing. This enables a continuous pH control and adjustment during dissolution of ionisable compounds. The results of the pH adjustment indicate that the system can compensate even rapid pH changes after addition of a basic or acidic moiety in amounts corresponding up to 90% of the overall buffer capacity. The results of the dissolution tests performed for a model formulation containing ionizable compounds (Nexium 20mg mups) indicate that both the simulated fasting intraluminal pH-profiles and the buffer species can significantly affect the dissolution process by changing the lag time prior to initial drug release and the release rate of the model compound. A prediction of the in vivo release behaviour of this formulation is thus most likely strongly related to the test conditions such as pH and buffer species. Copyright © 2013 Elsevier B.V. All rights reserved.

Protein-Water and Protein-Buffer Interactions in the Aqueous Solution of an Intrinsically Unstructured Plant Dehydrin: NMR Intensity and DSC Aspects

PubMed Central

Tompa, P.; Bánki, P.; Bokor, M.; Kamasa, P.; Kovács, D.; Lasanda, G.; Tompa, K.

2006-01-01

Proton NMR intensity and differential scanning calorimetry measurements were carried out on an intrinsically unstructured late embryogenesis abundant protein, ERD10, the globular BSA, and various buffer solutions to characterize water and ion binding of proteins by this novel combination of experimental approaches. By quantifying the number of hydration water molecules, the results demonstrate the interaction between the protein and NaCl and between buffer and NaCl on a microscopic level. The findings overall provide direct evidence that the intrinsically unstructured ERD10 not only has a high hydration capacity but can also bind a large amount of charged solute ions. In accord, the dehydration stress function of this protein probably results from its simultaneous action of retaining water in the drying cells and preventing an adverse increase in ionic strength, thus countering deleterious effects such as protein denaturation. PMID:16798808

Three-Stream, Bicarbonate-Based Hemodialysis Solution Delivery System Revisited: With an Emphasis on Some Aspects of Acid-Base Principles.

PubMed

Lew, Susie Q; Kohn, Orly F; Cheng, Yuk-Lun; Kjellstrand, Carl M; Ing, Todd S

2017-06-01

Hemodialysis patients can acquire buffer base (i.e., bicarbonate and buffer base equivalents of certain organic anions) from the acid and base concentrates of a three-stream, dual-concentrate, bicarbonate-based, dialysis solution delivery machine. The differences between dialysis fluid concentrate systems containing acetic acid versus sodium diacetate in the amount of potential buffering power were reviewed. Any organic anion such as acetate, citrate, or lactate (unless when combined with hydrogen) delivered to the body has the potential of being converted to bicarbonate. The prescribing physician aware of the role that organic anions in the concentrates can play in providing buffering power to the final dialysis fluid, will have a better knowledge of the amount of bicarbonate and bicarbonate precursors delivered to the patient. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Quantitative Correlation between Viscosity of Concentrated MAb Solutions and Particle Size Parameters Obtained from Small-Angle X-ray Scattering.

PubMed

Fukuda, Masakazu; Moriyama, Chifumi; Yamazaki, Tadao; Imaeda, Yoshimi; Koga, Akiko

2015-12-01

To investigate the relationship between viscosity of concentrated MAb solutions and particle size parameters obtained from small-angle X-ray scattering (SAXS). The viscosity of three MAb solutions (MAb1, MAb2, and MAb3; 40-200 mg/mL) was measured by electromagnetically spinning viscometer. The protein interactions of MAb solutions (at 60 mg/mL) was evaluated by SAXS. The phase behavior of 60 mg/mL MAb solutions in a low-salt buffer was observed after 1 week storage at 25°C. The MAb1 solutions exhibited the highest viscosity among the three MAbs in the buffer containing 50 mM NaCl. Viscosity of MAb1 solutions decreased with increasing temperature, increasing salt concentration, and addition of amino acids. Viscosity of MAb1 solutions was lowest in the buffer containing histidine, arginine, and aspartic acid. Particle size parameters obtained from SAXS measurements correlated very well with the viscosity of MAb solutions at 200 mg/mL. MAb1 exhibited liquid-liquid phase separation at a low salt concentration. Simultaneous addition of basic and acidic amino acids effectively suppressed intermolecular attractive interactions and decreased viscosity of MAb1 solutions. SAXS can be performed using a small volume of samples; therefore, the particle size parameters obtained from SAXS at intermediate protein concentration could be used to screen for low viscosity antibodies in the early development stage.

Expanding pH screening space using multiple droplets with secondary buffers for protein crystallization

NASA Astrophysics Data System (ADS)

Zhang, Chen-Yan; Dong, Chen; Lu, Xiao-Li; Wang, Bei; He, Tian-Yuan; Yang, Rui-Zeng; Lin, Hua-Long; Yang, Xue-Zhou; Yin, Da-Chuan

2017-04-01

We have proposed a rational strategy for selecting a suitable pH of protein solution based on protein biochemical properties. However, it is difficult to use this strategy for biochemical properties unknown proteins. In this paper, a simpler and faster pH buffer strategy was proposed. An additional pH-controlling buffer was added to crystallization droplet mixed with protein solution and commercial crystallization reagents to adjust its pH. The results revealed that protein crystallization success rates were enhanced by this strategy due to expansion of the pH screening space, which was closely related with protein solubility. Thus, the possibility of reaching supersaturation was increased by using this strategy.

Microwave assisted synthesis of bis and tris(ω-bromoacetophenones): versatile precursors for novel bis(imidazo[1,2-a]pyridines), bis(imidazo[1,2-a]pyrimidines) and their tris-analogs

PubMed Central

2013-01-01

Background α-Bromination of the side chain of aromatic ketones using NBS in the presence of p-toluenesulfonic acid (p-TsOH) in acetonitrile is very common. However, regioselective bromination of bis and tris(ω-bromoacetophenones) with NBS in the presence of p-TsOH in acetonitrile under microwave irradiation is quite novel. The bis- and tris(ω-bromoacetophenones) are used in synthesis of bis and tris(heterocycles). bis(heterocycles) have received a great deal of attention, because many biologically active natural and synthetic products have molecular symmetry. The use of the pressurized microwave irradiation is very advantageous to many syntheses and provide a large rate enhancement. Results Bis and tris(ω-bromoacetophenones) were obtained as single monobrominated derivatives in a shorter time than the conventional conditions. The results clearly demonstrate the better reactivity and selectivity of NBS/p-TsOH/CH3CN as a brominating mixture under microwave conditions. The reaction of bis and tris(ω-bromoacetophenone) with 2-aminopyridine and 2-aminopyrimidine proceeded smoothly in a mixture of anhydrous ethanol and DMF under reflux or using 300 W/105°C/ 20 min microwave irradiation conditions to afford the corresponding bis(imidazo[1,2-a]pyridine), bis(imidazo[1,2-a]pyrimidine) and tris(imidazo[1,2-a]pyridine) derivatives in moderate to excellent yields. The carbonyl analogue of the targeted bis(imidazopyridines) could be synthesized by the reaction of N,N-dimethyl-N'-(pyridin-2-yl)formimidamide with bis(ω-bromoacetophenone) in refluxing ethanol. The structures of the newly synthesized compounds were confirmed by their spectral data as well as their elemental analyses. Conclusion In conclusion, selective α-bromination of bis- and tris(acetophenones) has been accomplished efficiently utilizing NBS/p-TsOH/CH3CN under microwave irradiation. In addition, a facile synthesis of novel series of bis- and tris(imidazopyridine) and bis(imidazopyrimidine) derivatives. PMID:23782550

GATA4-mediated cardiac hypertrophy induced by D-myo-inositol 1,4,5-tris-phosphate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu Zhiming; Zhu Shanjun; Liu Daoyan

2005-12-16

We evaluated the effects of D-myo-inositol 1,4,5-tris-phosphate on cardiac hypertrophy. D-myo-inositol 1,4,5-tris-phosphate augmented cardiac hypertrophy as evidenced by its effects on DNA synthesis, protein synthesis, and expression of immediate-early genes c-myc and c-fos, {beta}-myosin heavy chain, and {alpha}-actin. The administration of D-myo-inositol 1,4,5-tris-phosphate increased the expression of nuclear factor of activated T-cells and cardiac-restricted zinc finger transcription factor (GATA4). Real-time quantitative RT-PCR showed that D-myo-inositol 1,4,5-tris-phosphate-induced GATA4 mRNA was significantly enhanced even in the presence of the calcineurin inhibitor, cyclosporine A. The effect of D-myo-inositol 1,4,5-tris-phosphate was blocked after inhibition of inositol-trisphosphate receptors but not after inhibition of c-Raf/mitogen-activated proteinmore » kinase kinase (MEK)/mitogen-activated protein kinase (ERK) or p38 mitogen-activated protein kinase pathways. The study shows that D-myo-inositol 1,4,5-tris-phosphate-induced cardiac hypertrophy is mediated by GATA4 but independent from the calcineurin pathway.« less

Diamond-based electrochemical aptasensor realizing a femtomolar detection limit of bisphenol A.

PubMed

Ma, Yibo; Liu, Junsong; Li, Hongdong

2017-06-15

In this study, we designed and fabricated an electrochemical impedance aptasensor based on Au nanoparticles (Au-NPs) coated boron-doped diamond (BDD) modified with aptamers, and 6-mercapto-1-hexanol (MCH) for the detection of bisphenol A (BPA). The constructed BPA aptasensor exhibits good linearity from 1.0×10 -14 to 1.0×10 -9 molL -1 . The detection limitation of 7.2×10 -15 molL -1 was achieved, which can be attributed to the synergistic effect of combining BDD with Au-NPs, aptamers, and MCH. The examine results of BPA traces in Tris-HCl buffer and in milk, UV spectra of aptamer/BPA and interference test revealed that the novel aptasensors are of high sensitivity, specificity, stability and repeatability, which could be promising in practical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

The study of a fluorescent biosensor based on polyelectrolyte microcapsules with encapsulated glucose oxidase

NASA Astrophysics Data System (ADS)

Kazakova, L. I.; Sirota, N. P.; Sirota, T. V.; Shabarchina, L. I.

2017-09-01

A fluorescent biosensor is synthesized and described. The biosensor consists of polyelectrolyte microcapsules with glucose oxidase (GOx) entrapped in the cavities and an oxygen-sensitive fluorescent indicator Ru(dpp) immobilized in shells, where Ru(dpp) is tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) dichloride. The theoretical activity of the encapsulated GOx and the effect storage time and medium composition have on the stability of sensor microcapsules are determined from polarographic measurements. No change in the activity of the encapsulated enzyme and or its loss to the storage medium are detected over the test period. The dispersion medium (water or a phosphate buffer) are shown to have no effect on the activity of microcapsules with immobilized GOx. The described optical sensor could be used as an alternative to electrochemical sensors for in vitro determination of glucose in the clinically important range of concentrations (up to 10 mmol/L).

High-performance liquid chromatographic separation of human haemoglobins. Simultaneous quantitation of foetal and glycated haemoglobins.

PubMed

Bisse, E; Wieland, H

1988-12-29

A high-performance liquid chromatographic system, which uses a weak cation exchanger (PolyCATA) together with Bis-Tris buffer (pH 6.47-7.0) and sodium acetate gradients, is described. Samples from adults and newborns were analysed and a clean separation of many minor and major normal and abnormal haemoglobin (Hb) variants was greatly improved. The method allows the separation of minor foetal haemoglobin (HbF) variants and the simultaneous quantitation of HbF and glycated HbA. HbF values correlated well with those obtained by the alkali denaturation method (r = 0.997). The glycated haemoglobin (HbAIc) levels measured in patients with high HbF concentrations correlated with the total glycated haemoglobin determined by bioaffinity chromatography (r = 0.973). The procedure is useful for diagnostic applications and affords an effective and sensitive way of examining blood samples for haemoglobin abnormalities.

Binding of warfarin influences the acid-base equilibrium of H242 in sudlow site I of human serum albumin.

PubMed

Perry, Jennifer L; Goldsmith, Michael R; Williams, T Richard; Radack, Kyle P; Christensen, Trine; Gorham, Justin; Pasquinelli, Melissa A; Toone, Eric J; Beratan, David N; Simon, John D

2006-01-01

Sudlow Site I of human serum albumin (HSA) is located in subdomain IIA of the protein and serves as a binding cavity for a variety of ligands. In this study, the binding of warfarin (W) is examined using computational techniques and isothermal titration calorimetry (ITC). The structure of the docked warfarin anion (W-) to Site I is similar to that revealed by X-ray crystallography, with a calculated binding constant of 5.8 x 10(5) M(-1). ITC experiments (pH 7.13 and I = 0.1) carried out in three different buffers (MOPs, phosphate and Tris) reveal binding of W- is accompanied by uptake of 0.30+/-0.02 protons from the solvent. This measurement suggests that the binding of W- is stabilized by an ion-pair interaction between protonated H242 and the phenoxide group of W-.

Influence of the chloride ion concentration on the corrosion of high-purity Mg, ZE41 and AZ91 in buffered Hank's solution.

PubMed

Taltavull, C; Shi, Z; Torres, B; Rams, J; Atrens, A

2014-02-01

This research studied the influence of the chloride ion concentration on the corrosion behaviour of high-purity magnesium (Mg) and two Mg alloys in Hank's solution, using hydrogen evolution and weight loss. A buffer based on CO2 and NaHCO3 was used to maintain the pH constant. The corrosion behaviour was governed by a partially protective surface film, and film breakdown by the chloride ions. The carbonated calcium phosphate layer that formed in Hank's solution was important in determining the protective properties of the surface film.

Delivery of resveratrol, a red wine polyphenol, from solutions and hydrogels via the skin.

PubMed

Hung, Chi-Feng; Lin, Yin-Ku; Huang, Zih-Rou; Fang, Jia-You

2008-05-01

Resveratrol, the main active polyphenol in red wine, has been demonstrated to show benefits against skin disorders. The bioavailability of orally administered resveratrol is insufficient to permit high enough drug concentrations for systemic therapy. In this study, we examined the feasibility of the topical/transdermal delivery of resveratrol. The effects of vehicles on the in vitro permeation and skin deposition from saturated solutions such as aqueous buffers and soybean oil were investigated. The general trend for the delivery from solutions was: pH 6 buffer=pH 8 buffer>10% glycerol formal in pH 6 buffer>pH 9.9 buffer>pH 10.8 buffer>soybean oil. A linear relationship was established between the permeability coefficient (K(p)) and drug accumulation in the skin reservoir. Viable epidermis/dermis served as the predominant barrier for non-ionic resveratrol permeation. On the other hand, both the stratum corneum (SC) and viable skin acted as barriers to anionic resveratrol. Several prototype hydrogel systems were also studied as resveratrol vehicles. The viscosity but not the polarity of the hydrogels controlled resveratrol permeation/deposition. Piceatannol, a derivative of resveratrol with high pharmacological activity, showed 11.6-fold lower skin permeation compared to resveratrol. The safety profiles of resveratrol suggested that the hydrogel caused no SC disruption or skin erythema. It was concluded that delivery via a skin route may be a potent way to achieve the therapeutic effects of resveratrol. This is the first report to establish the permeation profiles for topically applied resveratrol.

The adsorption mechanism of nortryptiline on C18-bonded discovery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gritti, Fabrice; Guiochon, Georges A

2005-08-01

The adsorption isotherms of an ionizable compound, nortriptyline, were accurately measured by frontal analysis (FA) on a C{sub 18}-Discovery column, first without buffer (in an aqueous solution of acetonitrile at 15%, v/v of ACN), then with a buffer (in 28%, v/v ACN solution). The buffers were aqueous solutions containing 20 mM of formic acid or a phosphate buffer at pH 2.70. The linear range of the isotherm could not be reached with the non-buffered mobile phase using a dynamic range larger than 40,000 (from 1.2 x 10{sup -3} g/L to 50 g/L). With a 20 mM buffer in the liquidmore » phase, the isotherm is linear for concentrations of nortriptyline inferior to 10{sup -3} g/L (or 3 {micro} mol/L). The adsorption energy distribution (AED) was calculated to determine the heterogeneity of the adsorption process. AED and FA were consistent and lead to a trimodal distribution. A tri-Moreau and a tri-Langmuir isotherm models accounted the best for the adsorption of nortriptyline without and with buffer, respectively. The nature of the buffer affects significantly the middle-energy sites while the properties of the lowest and highest of the three types of energy sites are almost unchanged. The desorption profiles of nortriptyline show some anomalies in relation with the formation of a complex multilayer adsorbed phase of acetonitrile whose excess isotherm was measured by the minor disturbance method. The C{sub 18}-Discovery column has about the same total saturation capacity, around 200 g of nortriptyline per liter of adsorbent (or 116 mg/g), with or without buffer. About 98-99% of the available surface consists in low energy sites. The coexistence of these different types of sites on the surface solves the McCalley's enigma, that the column efficiency begins to drop rapidly when the analyte concentration reaches values that are almost one hundred times lower than those that could be predicted from the isotherm data acquired under the same experimental conditions. Due to the presence of some relatively rare high energy sites, the largest part of the saturation capacity is not practically useful.« less

Production of .sup.203 Pb-tris-hydroxymethyl amino methane

DOEpatents

Lambrecht, Richard M.; Packer, Samuel; Merrill, Jerald C.; Atkins, Harold L.; Wolf, Alfred P.; Bradley-Moore, Patrick R.

1977-01-01

.sup.203 Pb-tris complex injected for use in the detection and localization of tumors. The lead-203 is produced from the deuteron bombardment of a thallium target and chemically separated from the thallium. The tris is added which complexes with the lead-203.

Synthesis of triazole-based and imidazole-based zinc catalysts

DOEpatents

Valdez, Carlos A.; Satcher, Jr., Joe H.; Aines, Roger D.; Baker, Sarah E.

2013-03-12

Various methods and structures of complexes and molecules are described herein related to a zinc-centered catalyst for removing carbon dioxide from atmospheric or aqueous environments. According to one embodiment, a method for creating a tris(triazolyl)pentaerythritol molecule includes contacting a pentaerythritol molecule with a propargyl halide molecule to create a trialkyne molecule, and contacting the trialkyne molecule with an azide molecule to create the tris(triazolyl)pentaerythritol molecule. In another embodiment, a method for creating a tris(imidazolyl)pentaerythritol molecule includes alkylating an imidazole 2-carbaldehyde molecule to create a monoalkylated aldehyde molecule, reducing the monoalkylated aldehyde molecule to create an alcohol molecule, converting the alcohol molecule to create an alkyl halide molecule using thionyl halide, and reacting the alkyl halide molecule with a pentaerythritol molecule to create a tris(imidazolyl)pentaerythritol molecule. In another embodiment, zinc is bound to the tris(triazolyl)pentaerythritol molecule to create a zinc-centered tris(triazolyl)pentaerythritol catalyst for removing carbon dioxide from atmospheric or aqueous environments.

Cross-linkable graphene oxide embedded nanocomposite hydrogel with enhanced mechanics and cytocompatibility for tissue engineering.

PubMed

Liu, Xifeng; Miller, A Lee; Waletzki, Brian E; Lu, Lichun

2018-05-01

Graphene oxide (GO) is an attractive material that can be utilized to enhance the modulus and conductivities of substrates and hydrogels. To covalently cross-link graphene oxide sheets into hydrogels, abundant cross-linkable double bonds were introduced to synthesize the graphene-oxide-tris-acrylate sheet (GO-TrisA). Polyacrylamide (PAM) nanocomposite hydrogels were then fabricated with inherent covalently and permanently cross-linked GO-TrisA sheets. Results showed that the covalently cross-linked GO-TrisA/PAM nanocomposite hydrogel had enhanced mechanical strength, thermo stability compared with GO/PAM hydrogel maintained mainly by hydrogen bonding between PAM chains and GO sheets. In vitro cell study showed that the covalently cross-linked rGO-TrisA/PAM nanocomposite hydrogel had excellent cytocompatibility after in situ reduction. These results suggest that rGO-TrisA/PAM nanocomposite hydrogel holds great potential for tissue engineering applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1247-1257, 2018. © 2018 Wiley Periodicals, Inc.

Internal acid buffering in San Joaquin Valley fog drops and its influence on aerosol processing

NASA Astrophysics Data System (ADS)

Collett, Jeffrey L.; Hoag, Katherine J.; Rao, Xin; Pandis, Spyros N.

Although several chemical pathways exist for S(IV) oxidation in fogs and clouds, many are self-limiting: as sulfuric acid is produced and the drop pH declines, the rates of these pathways also decline. Some of the acid that is produced can be buffered by uptake of gaseous ammonia. Additional internal buffering can result from protonation of weak and strong bases present in solution. Acid titrations of high pH fog samples (median pH=6.49) collected in California's San Joaquin Valley reveal the presence of considerable internal acid buffering. In samples collected at a rural location, the observed internal buffering could be nearly accounted for based on concentrations of ammonia and bicarbonate present in solution. In samples collected in the cities of Fresno and Bakersfield, however, significant additional, unexplained buffering was present over a pH range extending from approximately four to seven. The additional buffering was found to be associated with dissolved compounds in the fogwater. It could not be accounted for by measured concentrations of low molecular weight ( C1- C3) carboxylic acids, S(IV), phosphate, or nitrophenols. The amount of unexplained buffering in individual fog samples was found to correlate strongly with the sum of sample acetate and formate concentrations, suggesting that unmeasured organic species may be important contributors. Simulation of a Bakersfield fog episode with and without the additional, unexplained buffering revealed a significant impact on the fog chemistry. When the additional buffering was included, the simulated fog pH remained 0.3-0.7 pH units higher and the amount of sulfate present after the fog evaporated was increased by 50%. Including the additional buffering in the model simulation did not affect fogwater nitrate concentrations and was found to slightly decrease ammonium concentrations. The magnitude of the buffering effect on aqueous sulfate production is sensitive to the amount of ozone present to oxidize S(IV) in these high pH fogs.

Online monitoring of electrocatalytic reactions of alcohols at platinum and gold electrodes in acidic, neutral and alkaline media by capillary electrophoresis with contactless conductivity detection (EC-CE-C4 D).

PubMed

Ferreira Santos, Mauro Sérgio; Silva Lopes, Fernando; Gutz, Ivano Gebhardt Rolf

2017-11-01

An EC-CE-C 4 D flow system was applied to the investigation of electrocatalytic processes by monitoring carboxylic acids formed during the electro-oxidation at various potentials of primary alcohols (mixture of 1 mmol/L of ethanol, n-propanol, n-butanol and n-pentanol) in acidic, neutral and alkaline media. The electro-oxidation was carried out on gold and platinum disk electrodes (3 mm of diameter) in a thin-layer electrochemical flow cell. Products were sampled 50 μm apart from the electrode directly into the capillary. All the generated carboxylates were determined in near real time (less than 2 min) by CE-C 4 D in counter-flow mode, with Tris/HCl buffer solution (pH 8.6) as BGE. Long sequences of 5-min experiments were run automatically, exploring the applied potential, electrolysis time and solution composition. Electro-oxidation at 1.5 V (versus Ag/AgCl quasi-reference) during 50 s in acidic medium was found appropriate for both Pt and Au electrodes when the determination of alcohols after derivatization is intended. A noteworthy selectivity effect was observed on the Au electrode. The signal corresponding to pentanoate is similar on both electrodes while the signal of ethanoate (acetate) is four times larger on gold than on platinum. The carboxylate signals were lower in alkaline medium (below the determination limit on Pt) than in acidic and neutral media. On gold, the formation of carboxylates was anticipated (0.85 V in alkaline medium versus 1.40 V in neutral medium). The automatic online monitoring of electrochemical processes by EC-CE-C 4 D holds great potential to investigate ionic/ionizable intermediates/products of new electrocatalysts and/or alternative fuels. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Visual test of subparts per billion-level mercuric ion with a gold nanoparticle probe after preconcentration by hollow fiber supported liquid membrane.

PubMed

Tan, Zhi-qiang; Liu, Jing-fu

2010-05-15

With the combination of the gold nanoparticle (AuNP)-based visual test with hollow fiber supported liquid membrane (HFSLM) extraction, a highly sensitive and selective method was developed for field detection of mercuric ion (Hg(2+)) in environmental waters. Hg(2+) in water samples was extracted through HFSLM and trapped in the aqueous acceptor and then visually detected based on the red-to-blue color change of 3-mercaptopropionic acid-functionalized AuNP (MPA-AuNP) probe. The highest extraction efficiency of Hg(2+) was obtained by using a 600 mL sample (pH 8.0, 2.0% (w/v) NaCl), approximately 35 microL of acceptor (10 mM of 2,6-pyridinedicarboxylic acid, pH 4.0) filled in the lumen of a polypropylene hollow fiber tubing (55 cm in length, 50 microm wall thickness, 280 microm inner diameter), a liquid membrane of 2.0% (w/v) trioctycphosphine oxide in undecane, and a shaking rate of 250 rpm. The chromegenic reaction was conducted by incubating the mixture of MPA-AuNP stock solution (12 microL, 15 nM), Tris-borate buffer solution (18 microL, 0.2 M, pH 9.5), and acceptor (30 microL) at 30 degrees C for 1 h. The detection limit can be adjusted to 0.8 microg/L Hg(2+) (corresponding to an enrichment factor of approximately 1000 in the HFSLM) and 2.0 microg/L Hg(2+) (the U.S. Environmental Protection Agency limit of [Hg(2+)] for drinkable water) by using extraction times of 3 and 1 h, respectively. The proposed method is extremely specific for Hg(2+) with tolerance to at least 1000-fold of other environmentally relevant heavy and transition metal ions and was successfully applied to detect Hg(2+) in a certified reference water sample, as well as real river, lake, and tap water samples.

Crystal structures of the psychrophilic alpha-amylase from Alteromonas haloplanctis in its native form and complexed with an inhibitor.

PubMed Central

Aghajari, N.; Feller, G.; Gerday, C.; Haser, R.

1998-01-01

Alteromonas haloplanctis is a bacterium that flourishes in Antarctic sea-water and it is considered as an extreme psychrophile. We have determined the crystal structures of the alpha-amylase (AHA) secreted by this bacterium, in its native state to 2.0 angstroms resolution as well as in complex with Tris to 1.85 angstroms resolution. The structure of AHA, which is the first experimentally determined three-dimensional structure of a psychrophilic enzyme, resembles those of other known alpha-amylases of various origins with a surprisingly greatest similarity to mammalian alpha-amylases. AHA contains a chloride ion which activates the hydrolytic cleavage of substrate alpha-1,4-glycosidic bonds. The chloride binding site is situated approximately 5 angstroms from the active site which is characterized by a triad of acid residues (Asp 174, Glu 200, Asp 264). These are all involved in firm binding of the Tris moiety. A reaction mechanism for substrate hydrolysis is proposed on the basis of the Tris inhibitor binding and the chloride activation. A trio of residues (Ser 303, His 337, Glu 19) having a striking spatial resemblance with serine-protease like catalytic triads was found approximately 22 angstroms from the active site. We found that this triad is equally present in other chloride dependent alpha-amylases, and suggest that it could be responsible for autoproteolytic events observed in solution for this cold adapted alpha-amylase. PMID:9541387

Closed-form solutions of performability. [modeling of a degradable buffer/multiprocessor system

NASA Technical Reports Server (NTRS)

Meyer, J. F.

1981-01-01

Methods which yield closed form performability solutions for continuous valued variables are developed. The models are similar to those employed in performance modeling (i.e., Markovian queueing models) but are extended so as to account for variations in structure due to faults. In particular, the modeling of a degradable buffer/multiprocessor system is considered whose performance Y is the (normalized) average throughput rate realized during a bounded interval of time. To avoid known difficulties associated with exact transient solutions, an approximate decomposition of the model is employed permitting certain submodels to be solved in equilibrium. These solutions are then incorporated in a model with fewer transient states and by solving the latter, a closed form solution of the system's performability is obtained. In conclusion, some applications of this solution are discussed and illustrated, including an example of design optimization.

Stability of the Stevia-Derived Sweetener Rebaudioside A in Solution as Affected by Ultraviolet Light Exposure.

PubMed

Zhang, Jiewen; Bell, Leonard N

2017-04-01

Rebaudioside A is a natural noncaloric high-potency sweetener extracted from the leaves of Stevia rebaudiana. With rebaudioside A use increasing in foods, understanding the factors affecting its stability is necessary. This project evaluated the degradation rate constants of rebaudioside A in water, 0.1 M phosphate buffer, and 0.1 M citrate buffer at pH 3 and 7 as a function of ultraviolet (UV) light intensity (365 nm, 0 μW/cm 2 for dark conditions, 27 μW/cm 2 for low intensity, and 190 μW/cm 2 for high intensity) at 32.5 °C. Rebaudioside A stability was adversely affected by light exposure. The pseudo-1st-order degradation rate constants increased significantly (P < 0.05) with increasing light intensity in all solutions. Under dark conditions, rebaudioside A in phosphate buffers was more susceptible to breakdown than in water and citrate buffers at both pH levels. However, exposure to UV light resulted in rebaudioside A degradation occurring approximately 10 times faster in citrate than in phosphate buffers at both pH levels. The sensitivity of rebaudioside A to UV light was greater in citrate buffers than in water or phosphate buffers. The use of light-protective packaging for beverages containing rebaudioside A will improve its stability. © 2017 Institute of Food Technologists®.

An efficient buffer-mediated control between free radical substitution and proton-coupled electron transfer: dehalogenation of iodoethane by the α-hydroxyethyl radical in aqueous solution.

PubMed

Ljubić, Ivan; Matasović, Brunislav; Bonifačić, Marija

2013-11-07

A remarkable buffer-mediated control between free-radical substitution (FRS) and proton-coupled electron transfer (PCET) is demonstrated for the reaction between iodoethane and the α-hydroxyethyl radical in neutral aqueous solution in the presence of bicarbonate or phosphate buffer. The reaction is initiated by the γ-radiolysis of the water solvent, and the products, either the iodine atom (FRS) or anion (PCET), are analysed using ion chromatographic and spectrophotometric techniques. A detailed insight into the mechanism is gained by employing density functional theory (M06-2X), Møller-Plesset perturbation treatment to the second order (MP2), and multireference methods (CASSCF/CASPT2). Addition of a basic buffer anion is indispensable for the reaction to occur and the competition between the two channels depends subtly on its proton accepting affinity, with FRS being the dominant channel in the phosphate and PCET in the bicarbonate containing solutions. Unlike the former, the latter channel sustains a chain-like process which significantly enhances the dehalogenation. The present systems furnish an example of the novel PCET/FRS dichotomy, as well as insights into possibilities of its efficient control.

Biocompatibility of a bicarbonate-buffered amino-acid-based solution for peritoneal dialysis.

PubMed

Bender, Thorsten O; Witowski, Janusz; Aufricht, Christoph; Endemann, Michaela; Frei, Ulrich; Passlick-Deetjen, Jutta; Jörres, Achim

2008-09-01

Amino-acid-based peritoneal dialysis (PD) fluids have been developed to improve the nutritional status of PD patients. As they may potentially exacerbate acidosis, an amino-acid-containing solution buffered with bicarbonate (Aminobic) has been proposed to effectively maintain acid-base balance. The aim of this study was to evaluate the mesothelial biocompatibility profile of this solution in comparison with a conventional low-glucose-based fluid. Omentum-derived human peritoneal mesothelial cells (HPMC) were preexposed to test PD solutions for up to 120 min, then allowed to recover in control medium for 24 h, and assessed for heat-shock response, viability, and basal and stimulated cytokine [interleukin (IL)-6] and prostaglandin (PGE(2)) release. Acute exposure of HPMC to conventional low-glucose-based PD solution resulted in a time-dependent increase in heat-shock protein (HSP-72) expression, impaired viability, and reduced ability to release IL-6 in response to stimulation. In contrast, in cells treated with Aminobic, the expression of HSP-72 was significantly lower, and viability and cytokine-producing capacity were preserved and did not differ from those seen in control cells. In addition, exposure to Aminobic increased basal release of IL-6 and PGE(2). These data point to a favorable biocompatibility profile of the amino-acid-based bicarbonate-buffered PD solution toward HPMC.

Investigations Concerning Hydrolysis and Stabilization of Antiradiation Compounds

DTIC Science & Technology

1982-01-01

Stability of Unencapsulated WR 2721 31 V. DISCUSSION 35 A. Microencapsulation 35 1. Microspheres 35 2. Microcapsules 35 B. Hydrolytic Stability of...in 1.5 hours at 370C in buffered solutions of pH 1.0 or 3.0. 3^ The more promising microspheres and microcapsules released the WR 2721 within two...hours at pH 7.5 in buffered solutions. 4) Analytical procedures were developed for: "♦ WR 2721 (directly) in microcapsules using an HPLC

Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification.

PubMed

Ow, Yan X; Uthicke, Sven; Collier, Catherine J

2016-01-01

Under future ocean acidification (OA), increased availability of dissolved inorganic carbon (DIC) in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2), and three light treatments (35, 100, 380 μmol m(-2) s(-1)) for two weeks. DIC uptake mechanisms were separately examined by measuring net photosynthetic rates while subjecting C. serrulata and H. uninervis to changes in light and addition of bicarbonate (HCO3-) use inhibitors (carbonic anhydrase inhibitor, acetazolamide) and TRIS buffer (pH 8.0). We observed a strong dependence on energy driven H+-HCO3- co-transport (TRIS, which disrupts H+ extrusion) in C. serrulata under all light levels, indicating greater CO2 dependence in low light. This was confirmed when, after two weeks exposure, DIC enrichment stimulated maximum photosynthetic rates (Pmax) and efficiency (α) more in C. serrulata grown under lower light levels (36-60% increase) than for those in high light (4% increase). However, C. serrulata growth increased with both DIC enrichment and light levels. Growth, NPP and photosynthetic responses in H. uninervis increased with higher light treatments and were independent of DIC availability. Furthermore, H. uninervis was found to be more flexible in HCO3- uptake pathways. Here, light availability influenced productivity responses to DIC enrichment, via both carbon fixation and acquisition processes, highlighting the role of water quality in future responses to OA.

Assessment of basic seminal characteristics, sperm cryopreservation and heterologous in vitro fertilisation in the fishing cat (Prionailurus viverrinus).

PubMed

Thiangtum, Khongsak; Swanson, William F; Howard, JoGayle; Tunwattana, Wanchai; Tongthainan, Dakara; Wichasilpa, Wisid; Patumrattanathan, Pornchai; Pinyopoommintr, Tanu

2006-01-01

Conservation of the fishing cat, a threatened south-east Asian felid, could benefit from effective ex situ genetic management and breeding programmes, including the use of assisted reproduction. The aims of the present study were to: (1) characterise basal seminal traits of fishing cats in Thailand zoos; and (2) investigate the effect of cryopreservation on sperm motility, acrosomal integrity and in vitro function. Seminal traits were evaluated in electroejaculates collected from eight males. Spermatozoa were diluted in n-tris(hydroxymethyl)-methyl-2-aminoethanesulfonic acid Tris (TEST)-yolk buffer (TYB) without glycerol, then diluted further with TYB with glycerol (4% final concentration) at either 25 degrees C or after slow cooling to 5 degrees C and frozen in straws over liquid nitrogen vapour. After thawing, sperm function was assessed by insemination of viable domestic cat oocytes. Fishing cat ejaculates averaged (+/- s.e.m.) 43.6 +/- 14.2 x 10(6) motile spermatozoa with 33.5 +/- 6.8% normal sperm morphology. Semen processing had a negligible effect (P > 0.05) on sperm motility and acrosomal integrity, but values were reduced (P < 0.05) after thawing. All thawed samples fertilised domestic cat oocytes, with 62.1% (36/58) of mature oocytes cleaving. Glycerol addition at 5 degrees C resulted in higher (P < 0.05) post-thaw motility and intact acrosomes than glycerol addition at 25 degrees C. In conclusion, good-quality ejaculates can be obtained from Thai fishing cats and their spermatozoa exhibit adequate function after cryopreservation for in vitro fertilisation procedures.

Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification

PubMed Central

2016-01-01

Under future ocean acidification (OA), increased availability of dissolved inorganic carbon (DIC) in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2), and three light treatments (35, 100, 380 μmol m-2 s-1) for two weeks. DIC uptake mechanisms were separately examined by measuring net photosynthetic rates while subjecting C. serrulata and H. uninervis to changes in light and addition of bicarbonate (HCO3-) use inhibitors (carbonic anhydrase inhibitor, acetazolamide) and TRIS buffer (pH 8.0). We observed a strong dependence on energy driven H+-HCO3- co-transport (TRIS, which disrupts H+ extrusion) in C. serrulata under all light levels, indicating greater CO2 dependence in low light. This was confirmed when, after two weeks exposure, DIC enrichment stimulated maximum photosynthetic rates (Pmax) and efficiency (α) more in C. serrulata grown under lower light levels (36–60% increase) than for those in high light (4% increase). However, C. serrulata growth increased with both DIC enrichment and light levels. Growth, NPP and photosynthetic responses in H. uninervis increased with higher light treatments and were independent of DIC availability. Furthermore, H. uninervis was found to be more flexible in HCO3- uptake pathways. Here, light availability influenced productivity responses to DIC enrichment, via both carbon fixation and acquisition processes, highlighting the role of water quality in future responses to OA. PMID:26938454

In vitro digestion method for estimation of copper bioaccessibility in Açaí berry.

PubMed

Ruzik, Lena; Wojcieszek, Justyna

Copper is an essential trace element for humans and its deficiency can lead to numerous diseases. A lot of mineral supplements are available to increase intake of copper. Unfortunately, only a part of the total concentration of elements is available for human body. Thus, the aim of the study was to determine bioaccessibility of copper in Açai berry, known as a "superfood" because of its antioxidant qualities. An analytical methodology was based on size exclusion chromatography (SEC) coupled to a mass spectrometer with inductively coupled plasma (ICP MS) and on capillary liquid chromatography coupled to tandem mass spectrometer with electrospray ionization (µ-HPLC-ESI MS/MS). To extract various copper compounds, berries were treated with the following buffers: ammonium acetate, Tris-HCl, and sodium dodecyl sulfate (SDS). The best extraction efficiency of copper was obtained for SDS extract (88 %), while results obtained for Tris-HCl and ammonium acetate were very similar (47 and 48 %, respectively). After SEC-ICP-MS analysis, main signal was obtained for all extracts in the region of molecular mass about 17 kDa. A two-step model simulated gastric (pepsin) and gastrointestinal (pancreatin) digestion was used to obtain the knowledge about copper bioaccessibility. Copper compounds present in Açai berry were found to be highly bioaccessible. The structures of five copper complexes with amino acids such as aspartic acid, tyrosine, phenylalanine, were proposed after µ-HPLC-ESI MS/MS analysis. Obtained results show that copper in enzymatic extracts is bound by amino acids and peptides what leads to better bioavailability of copper for human body.

Comparison of phage pVIII and KLH as vector in inducing the production of cytokines in C57BL/6J mice.

PubMed

Su, Quan-Ping; Wen, De-Zhong; Yang, Qiong; Zhang, Yan-Hui; Liu, Chong; Wang, Li

2007-01-22

We have demonstrated that phage display Candida albicans (C. albicans) LKVIRK epitope was protective in systemically infected C57BL/6J mice. The different development from precursor Ths, Th1 or Th2, will result in a protective or nonprotective immune response. To compare the types of cytokines induced by biologically and chemically synthesized vectors, C57BL/6J mice were immunized with hybrid phage displaying the epitope of LKVIRK and by synthesized peptide epitope LKVIRKNIVKKMIE conjugated through cysteine to keyhole limpet haemocyanin (KLH). The production of cytokines in spleens of immunized mice and in splenocytes culture supernatants stimulated by homologous immunogen in vitro was studied by RT-PCR and quantitative sandwich ELISA. The results showed that, compared to Tris-EDTA buffer (TE, 1 mM Tris, 0.1 mM EDTA, pH 8.0) injected mice, the expressions of Th1 type cytokine IFN-gamma, IL-2 and IL-12 were increased in hybrid phage, KLH-C, and wild phage immunized mice, and there were no differences between mice immunized with hybrid phage and KLH-C. While the expression of Th2 type cytokine IL-10 was similar in all mice, IL-4 was not detected. We obtained the same results in mRNA and protein level. These findings indicated that as carriers, phage and KLH were similar in inducing the Th1 type cytokines expression. Comparing to peptide synthesis couple with a carrier protein for injection, phage may be an inexpensive and simple route to the production of effective vaccines.

DEVELOPMENT OF A SMALL CHAMBER METHOD FOR SVOC SINK EFFECT STUDY

EPA Science Inventory

This paper describes the details of the improved chamber system and reports the sink effect study for organophosphorus flame retardants (OP-FRs), including tris(2-chloroethyl) phosphate(TCEP), tris(1-chlor-2-propyl) phosphate (TCPP) and tris(1,3-dichloro-2-propyl) phosphate (TDC...

Isolation of high quality RNA from cereal seeds containing high levels of starch.

PubMed

Wang, Guifeng; Wang, Gang; Zhang, Xiaowei; Wang, Fang; Song, Rentao

2012-01-01

Cereals are an important source of food, feed and fuel with a rapidly increasing global demand. However, cereal seeds contain high levels of starch and polysaccharides, making the isolation of high quality RNA extremely difficult. To develop a novel method for extracting high quality total RNA from various starch- and polysaccharides-rich cereal seeds, such as maize, rice, sorghum and wheat. We developed a modified sodium dodecyl sulphate (SDS)/TRIzol method. The combined use of a Tris buffer (pH 9.0) and SDS before TRIzol extraction effectively resolved the problem of seed homogenate solidification in such a buffer. A high concentration of SDS was used separately, not only to promote cell lysis but also to effectively dissolve seed sample containing high levels of starch. Moreover, acid phenol saturated with 0.1  M citrate buffer (pH 4.3) was used to separate RNA from DNAs, proteins and high levels of starch. This rapid protocol was compared with other RNA isolation methods preferentially used for plants rich in polysaccharides and secondary metabolites. Gel electrophoresis analysis indicated that the extracted total RNA had good integrity without apparent DNA contamination. Furthermore, an A₂₆₀/₂₈₀ ratio of approximately 2.0, an A₂₆₀/₂₃₀ ratio of more than 2.0 and RIN values of more than 8.6 indicated that the isolated RNA was of high purity. The isolated RNA was suitable for subsequent molecular manipulations, such as reverse-transcription polymerase chain reaction (PCR), rapid amplification of cDNA ends (RACE) and real-time PCR. The study has described an easy, efficient and highly reproducible method for RNA isolation from various cereal seeds. Copyright © 2011 John Wiley & Sons, Ltd.

Ribonucleic Acid and Ribosomes of Bacillus stearothermophilus1

PubMed Central

Saunders, Grady F.; Campbell, L. Leon

1966-01-01

Saunders, Grady F. (University of Illinois, Urbana), and L. Leon Campbell. Ribonucleic acid and ribosomes of Bacillus stearothermophilus. J. Bacteriol. 91:332–339. 1966.—The ability of some thermophilic bacteria to grow at temperatures as high as 76 C emphasizes the remarkable thermal stability of their crucial macromolecules. An investigation of the ribonucleic acid (RNA) and ribosomes of Bacillus stearothermophilus was conducted. Washed log-phase cells were disrupted either by sonic treatment or by alumina grinding in 10−2m MgCl2–10−2m tris-(hydroxymethyl)aminomethane buffer, pH 7.4 (TM buffer). Ultracentrifugal analysis revealed peaks at 72.5S, 101S, and 135S, with the 101S peak being the most prominent. By lowering the Mg++ concentration to 10−3m, the ribosome preparation was dissociated to give 40S, 31S, and 54S peaks. These in turn were reassociated in the presence of 10−2m Mg++ to give the larger 73S and 135S particles. When heated in TM buffer, Escherichia coli ribosomes began a gradual dissociation at 58 C, and at 70 C underwent a large hyperchromic shift with a Tm at 72.8 C. In contrast, B. stearothermophilus ribosomes did not show a hyperchromic shift below 70 C; they had a Tm of 77.9 C. The thermal denaturation curves of the 4S, 16S, and 23S RNA from both organisms were virtually identical. The gross amino acid composition of B. stearothermophilus ribosomes showed no marked differences from that reported for E. coli ribosomes. These data suggest that the unusual thermal stability of B. stearothermophilus ribosomes may reflect either an unusual packing arrangement of the protein to the RNA or differences in the primary structure of the ribosomal proteins. Images PMID:5903099

Long Wavelength Excitation of Europium Luminescence in Extended, Carboline-Based Cryptates.

PubMed

Dee, Carolin; Esteban-Gómez, David; Platas-Iglesias, Carlos; Seitz, Michael

2018-06-05

Two new β-carboline-based tris(biaryl) europium cryptates are introduced. The extended antenna moiety incorporated into the cryptand frameworks enables the sensitization of europium emission with excitation wavelengths well above 450 nm. In aqueous solution, the cryptates show great complex stability, luminescence lifetimes around 0.5 ms, and absolute quantum yields of ca. 3%. In addition, the europium luminescence shows a well-defined pH-dependence in the physiologically interesting pH range 7-9.

A Critical Examination of the Reaction of Pyridoxal 5-Phosphate with Human Hemoglobin Ao

DTIC Science & Technology

1989-01-01

sodium borohydride gives unacceptable levels of methemoglobin (i.e., > 10%). Excessive foaming and methemoglobin formation can be partially avoided using...a biochemical level . By using new advances in HPLC column technology, we could better determine hetero- geneity in the product mixture due solely to... diphosphoglycerate (2,3-DPG). 6 SFH, which had been stripped of 2,3-DPG, was deoxygenated with nitrogen and treated with a solution of PLP in Tris

Titanium (III) cation selective electrode based on synthesized tris(2pyridyl) methylamine ionophore and its application in water samples

PubMed Central

Rezayi, Majid; Karazhian, Reza; Abdollahi, Yadollah; Narimani, Leila; Sany, Seyedeh Belin Tavakoly; Ahmadzadeh, Saeid; Alias, Yatimah

2014-01-01

The introduction of low detection limit ion selective electrodes (ISEs) may well pave the way for the determination of trace targets of cationic compounds. This research focuses on the detection of titanium (III) cation using a new PVC-membrane sensor based on synthesized tris(2pyridyl) methylamine (tpm) ionophore. The application and validation of the proposed sensor was done using potentiometric titration, inductively coupled plasma atomic emission spectrometry (ICP-AES), and atomic absorption spectrometry (AAS). The membrane sensor exhibited a Nernstian response to the titanium (III) cation over a concentration range of 1.0 × 10−6–1.0 × 10−2 M and pH range from 1–2.5. The Nernstian slope, the lower of detection (LOD), and the response time (t95%) of the proposed sensor were 29.17 ± 0.24 mV/dec, 7.9 × 10−7 M, and 20 s, respectively. The direct determination of 4–39 μg/ml of titanium (III) standard solution showed an average recovery of 94.60 and a mean relative standard deviation of 1.8 at 100.0 μg/ml. Finally, the utilization of the electrodes as end-point indicators for potentiometric titration with EDTA solutions for titanium (III) sensor was successfully carried out. PMID:24722576

Preparation and Structural Properties of InIII–H Complexes

PubMed Central

Sickerman, Nathaniel S.; Henry, Renée M.; Ziller, Joseph W.

2013-01-01

The use of the tripodal ligands tris[(N'-tert-butylureaylato)-N-ethyl]aminato ([H3buea]3−) and the sulfonamide-based N,N',N"-[2,2',2"-nitrilotris(ethane-2,1-diyl)]tris(2,4,6-trimethylbenzene-sulfonamidato) ([MST]3−) has led to the synthesis of two structurally distinct In(III)–OH complexes. The first example of a five-coordinate indium(III) complex with a terminal hydroxide ligand, K[InIIIH3buea(OH)], was prepared by addition of In(OAc)3 and water to a deprotonated solution of H6buea. X-ray diffraction analysis, as well as FTIR and 1H NMR spectroscopic methods, provided evidence for the formation of a monomeric In(III)–OH complex. The complex contains an intramolecular hydrogen bonding (H-bonding) network involving the In(III)–OH unit and [H3buea]3− ligand, which aided in isolation of the complex. Isotope labeling studies verified the source of the hydroxo ligand as water. Treatment of the [InIIIMST] complex with a mixture of 15-crown-5 ether and NaOH led to isolation of the complex [15-crown-5⊃NaI-(μ-OH)-InIIIMST], whose solid-state structure was confirmed using X-ray diffraction methods. Nuclear magnetic resonance studies on this complex suggest it retains its heterobimetallic structure in solution. PMID:25309019

Impact of the chemicals, essential for the purification process of strict Fe-hydrogenase, on the corrosion of mild steel.

PubMed

Rouvre, Ingrid; Gauquelin, Charles; Meynial-Salles, Isabelle; Basseguy, Régine

2016-06-01

The influence of additional chemical molecules, necessary for the purification process of [Fe]-hydrogenase from Clostridium acetobutylicum, was studied on the anaerobic corrosion of mild steel. At the end of the purification process, the pure [Fe-Fe]-hydrogenase was recovered in a Tris-HCl medium containing three other chemicals at low concentration: DTT, dithionite and desthiobiotin. Firstly, mild steel coupons were exposed in parallel to a 0.1 M pH7 Tris-HCl medium with or without pure hydrogenase. The results showed that hydrogenase and the additional molecules were in competition, and the electrochemical response could not be attributed solely to hydrogenase. Then, solutions with additional chemicals of different compositions were studied electrochemically. DTT polluted the electrochemical signal by increasing the Eoc by 35 mV 24 h after the injection of 300 μL of control solutions with DTT, whereas it drastically decreased the corrosion rate by increasing the charge transfer resistance (Rct 10 times the initial value). Thus, DTT was shown to have a strong antagonistic effect on corrosion and was removed from the purification process. An optimal composition of the medium was selected (0.5 mM dithionite, 7.5 mM desthiobiotin) that simultaneously allowed a high activity of hydrogenase and a lower impact on the electrochemical response for corrosion tests. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of Air Sampling Methods for Organophosphate Flame Retardants in Small Environmental Chambers

EPA Science Inventory

Organophosphorus flame retardants (OPFRs), such as tris(2-chloroethyl) phosphate (TCEP), tris(1-chlor-2-propyl) phosphate (TCPP), and tris(1,3-dichloro-2-propyl) phosphate (TDCPP), used as additives in industrial and consumer products are being detected in indoor air, house dust,...

Intramolecular aggregation and optical limiting properties of triazine-linked mono-, bis- and tris-phthalocyanines.

PubMed

Chen, Jun; Zhang, Tao; Wang, Shuangqing; Hu, Rui; Li, Shayu; Ma, Jin Shi; Yang, Guoqiang

2015-10-05

A series of triazine-linked mono-, bis- and tris-phthalocyanines are synthesized, intramolecular aggregation is found in bis- and tris-phthalocyanines via π-π stacking interaction. Theoretical and experimental studies reveal the formation of the intramolecular aggregation. The spectrographic, photophysical and nonlinear optical properties of these compounds are adjusted for the formation of the intramolecular aggregation. The bis-phthalocyanine dimer presents smaller fluorescence quantum yield, lower triplet formation yield and the triplet-minus-ground state extinction coefficient, which causes poorer optical limiting performance. It is interesting that the tris-phthalocyanine is composed of a mono-phthalocyanine part and a bis-phthalocyanine part, the optical limiting property of the tris-phthalocyanine is similar to that of mono-phthalocyanine. Copyright © 2015 Elsevier B.V. All rights reserved.

Degradation pattern of porous CaCO3 and hydroxyapatite microspheres in vitro and in vivo for potential application in bone tissue engineering.

PubMed

Zhong, Qiwei; Li, Wenhua; Su, Xiuping; Li, Geng; Zhou, Ying; Kundu, Subhas C; Yao, Juming; Cai, Yurong

2016-07-01

Despite superior clinical handling, excellent biocompatibility, biodegradation property of calcium phosphate needs to be improved to coincide with the rate of new bone formation. In this study, spherical CaCO3 are fabricated in the presence of the silk sericin and then transformed into porous hydroxyapatite (HAP) microspheres via hydrothermal method. The degradation behavior of obtained CaCO3, HAP and their mixture is first investigated in vitro. The result demonstrates that the weight loss of HAP microspheres are almost 24.3% after immersing in pH 7.40 Tris-HCl buffer solution for 12 weeks, which is far slower than that of spherical CaCO3 (97.5%). The degradation speed of the mixtures depends on the proportion of CaCO3 and HAP. The mixture with higher content of CaCO3 possesses a quicker degradation speed. The obtained CaCO3 and HAP microspheres are injected into subcutaneous tissue of ICR mice with the assistance of sodium alginate. The result in vivo also shows an obvious difference of degradation speed between the obtained CaCO3 and HAP microspheres, implying it is feasible to modulate the degradation property of the mixture through changing the proportion of CaCO3 and HAP The good cytocompatibility of the two kinds of microspheres is proved and a mild inflammation response is observed only at early stage of implantation. The job offers a simple method to modify the degradation properties of biomaterial for potential use in bone tissue engineering. Copyright © 2016 Elsevier B.V. All rights reserved.

Programmable pH buffers

DOEpatents

Gough, Dara Van; Huber, Dale L.; Bunker, Bruce C.; Roberts, Mark E.

2017-01-24

A programmable pH buffer comprises a copolymer that changes pK.sub.a at a lower critical solution temperature (LCST) in water. The copolymer comprises a thermally programmable polymer that undergoes a hydrophobic-to-hydrophilic phase change at the LCST and an electrolytic polymer that exhibits acid-base properties that are responsive to the phase change. The programmable pH buffer can be used to sequester CO.sub.2 into water.

Ultrastructural observation of the acid-base resistant zone of all-in-one adhesives using three different acid-base challenges.

PubMed

Tsujimoto, Miho; Nikaido, Toru; Inoue, Go; Sadr, Alireza; Tagami, Junji

2010-11-01

The aim of this study was to analyze the ultrastructure of the dentin-adhesive interface using two all-in-one adhesive systems (Clearfil Tri-S Bond, TB; Tokuyama Bond Force, BF) after different acid-base challenges. Three solutions were used as acidic solutions for the acid-base challenges: a demineralizing solution (DS), a phosphoric acid solution (PA), and a hydrochloric acid solution (HCl). After the acid-base challenges, the bonded interfaces were examined by scanning electron microscopy. Thickness of the acid-base resistant zone (ABRZ) created in PA and HCl was thinner than in DS for both adhesive systems. For BF adhesive, an eroded area was observed beneath the ABRZ after immersion in PA and HCl, but not in DS. Conversely for TB adhesive, the eroded area was observed only after immersion in PA. In conclusion, although the ABRZ was observed for both all-in-one adhesive systems, its morphological features were influenced by the ingredients of both the adhesive material and acidic solution.

The application of animal models to study the biocompatibility of bicarbonate-buffered peritoneal dialysis solutions.

PubMed

ter Wee, P M; Beelen, R H J; van den Born, J

2003-12-01

The application of animal models to study the biocompatibility of bicarbonate-buffered peritoneal dialysis solutions. Patients treated with peritoneal dialysis (PD) are at risk for development of ultrafiltration failure and peritonitis. These two significant complications can result in the termination of PD treatment. The relative unphysiologic composition of the currently used standard peritoneal dialysis fluids (PDF) is considered to be a major cause for the development of morphologic changes of the peritoneal membrane, ultimately resulting in ultrafiltration failure and probably contributing to changes in local defense mechanisms with the associated increased risk of peritonitis. In recent years, a major research focus has become the development of new and improved PD solutions. This has resulted in the development of an amino-acid-based PDF, a glucose polymer-based PDF, and several bicarbonate-buffered PDF. Typically, the first phase of biocompatibility testing of new PD solutions involves in vitro testing, employing isolated cells such as peritoneal macrophages or cell culture systems using human peritoneal mesothelial cells. The results of such evaluations are useful in providing insights into the biocompatibility performance of any given formulation, but suffer from several disadvantages, which can be better addressed using animal models. In vivo studies using animals permit the analysis of biocompatibility under conditions that allow for cell-to-cell interactions and dynamic changes in solution composition that more closely mimic the clinical situation. In this paper, we will review the use of animal models for the study of PDF biocompatibility and their application to the assessment of bicarbonate-buffered PDF.

Preparation and Properties of Hybrid Nanostructures of Zinc Tetraphenylporphyrinate and an Amphiphilic Copolymer of N-Vinylpyrrolidone in a Neutral Aqueous Buffer Solution

NASA Astrophysics Data System (ADS)

Kurmaz, S. V.; Gak, V. Yu.; Kurmaz, V. A.; Konev, D. V.

2018-02-01

Water-soluble forms of a hydrophobic dye, zinc tetraphenylporphyrinate, are obtained via its solubilization by polymer particles of the micellar type formed by a copolymer of N-vinylpyrrolidone with triethylene glycol dimethacrylate. Hydrodynamic radii R h and the size distribution of such particles in neutral aqueous buffer solutions are determined via dynamic light scattering. The electrochemical activity of the encapsulated dye is found, and its photochemical properties (absorption and fluorescence) are studied.

Ultrastructural investigations for reducing endothelial cell damage of vein grafts during CABG-operation and practical consequences.

PubMed

Hickethier, T; Dämmrich, J; Silber, R E; Finster, S; Elert, O

1999-02-01

In the present study the influence of different storage solutions on endothelial integrity or damage was investigated with direct methods particularly with transmission electron microscopy (TEM), scanning electron microscopy (SEM) and immunohistochemistry. Saphenous vein segments of 10 cm in length were taken surgically from 6 male CABG-patients (aged 60-70) under standardized conditions. Each vein segment was cut into rings, which were incubated at room temperature for 45 minutes in different storage solutions, particularly in 0.9% sodium chloride solution and in buffered solution (M 199) with 5% human serum albumin respectively. Then, the vein segments were fixed in 3.5% glutaraldehyde and prepared for scanning and transmission electron microscopy to evaluate the endothelial damage. In addition, immunohistochemical staining (CD34, PECAM and Factor VIII) was performed. When using 0.9% sodium chloride solution, the SEM-examination revealed that 55% of the cell population was destroyed. In comparison to these findings only 26% of the endothelial cell population was damaged when the venous segment was stored in buffered solution with 5% albumin (p<0.01). In immunohistochemistry (CD34, PECAM, Factor VIII) these findings were supported. This study demonstrates the importance of storage solutions in regard to endothelial integrity. For best preservation of endothelium it is necessary to modify conventional storage methods. So, storage in buffered solution with albumin has shown much better endothelial cell preservation compared with physiological saline which might reduce the obliteration rate of CABG in future.

Optimization of oligomeric enzyme activity in ionic liquids using Rhodotorula glutinis yeast phenylalanine ammonia lyase.

PubMed

Barron, Christiaan C; Sponagle, Brandon J D; Arivalagan, Pugazhendhi; D'Cunha, Godwin B

2017-01-01

Phenylalanine ammonia lyase (E.C.4.3.1.24, PAL) activity of Rhodotorula glutinis yeast has been demonstrated in four commonly used ionic liquids. PAL forward reaction was carried out in 1-butyl-3-methylimidazolium methyl sulfate ([BMIM][MeSO 4 ]), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF 4 ]), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF 6 ]) and 1-butyl-3-methylimidazolium lactate ([BMIM][lactate]). Our experiments have revealed that PAL is catalytically active in ionic liquids and the enzyme activity in ([BMIM][PF 6 ]) is comparable to that obtained in aqueous buffer medium. Different conditions were optimized for maximal PAL forward activity including time of incubation (30.0min) L -phenylalanine substrate concentration (30.0mM), nature of buffer (50.0mM Tris-HCl), pH (9.0), temperature (37°C), and speed of agitation (100 rev min -1 ). Under these optimized conditions, about 83% conversion of substrate to product was obtained for the PAL forward reaction that was determined using UV spectroscopy at 290nm. PAL reverse reaction in ([BMIM][PF 6 ]) was determined spectrophotometrically at 520nm; and about 59% substrate conversion was obtained. This data provides further knowledge in enzyme biocatalysis in non-aqueous media, and may be of importance when studying the function of other oligomeric/multimeric proteins and enzymes in ionic liquids. Copyright © 2016 Elsevier Inc. All rights reserved.

Development of a flow system for the determination of cadmium in fuel alcohol using vermicompost as biosorbent and flame atomic absorption spectrometry.

PubMed

Bianchin, Joyce Nunes; Martendal, Edmar; Mior, Renata; Alves, Vanessa Nunes; Araújo, Cleide Sandra Tavares; Coelho, Nívia Maria Melo; Carasek, Eduardo

2009-04-30

In this study a method for the determination of cadmium in fuel alcohol using solid-phase extraction with a flow injection analysis system and detection by flame atomic absorption spectrometry was developed. The sorbent material used was a vermicompost commonly used as a garden fertilizer. The chemical and flow variables of the on-line preconcentration system were optimized by means of a full factorial design. The selected factors were: sorbent mass, sample pH, buffer concentration and sample flow rate. The optimum extraction conditions were obtained using sample pH in the range of 7.3-8.3 buffered with tris(hydroxymethyl)aminomethane at 50 mmol L(-1), a sample flow rate of 4.5 mL min(-1) and 160 mg of sorbent mass. With the optimized conditions, the preconcentration factor, limit of detection and sample throughput were estimated as 32 (for preconcentration of 10 mL sample), 1.7 microg L(-1) and 20 samples per hour, respectively. The analytical curve was linear from 5 up to at least 50 microg L(-1), with a correlation coefficient of 0.998 and a relative standard deviation of 2.4% (35 microg L(-1), n=7). The developed method was successfully applied to spiked fuel alcohol, and accuracy was assessed through recovery tests, with recovery ranging from 94% to 100%.

40 CFR 721.10688 - Copper, chloro[tris(2-chloroethyl) phosphite-.kappa.P]-.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) phosphite-.kappa.P]-. 721.10688 Section 721.10688 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10688 Copper, chloro[tris(2-chloroethyl) phosphite-.kappa.P]-. (a... copper, chloro[tris(2-chloroethyl) phosphite-.kappa.P]- (PMN P-13-221; CAS No. 24484-01-3) is subject to...

Experimental determination of the hydrothermal solubility of ReS2 and the Re–ReO2 buffer assemblage and transport of rhenium under supercritical conditions

PubMed Central

Xiong, Yongliang; Wood, Scott A

2002-01-01

To understand the aqueous species important for transport of rhenium under supercritical conditions, we conducted a series of solubility experiments on the Re–ReO2 buffer assemblage and ReS2. In these experiments, pH was buffered by the K–feldspar–muscovite–quartz assemblage; in sulfur-free systems was buffered by the Re–ReO2 assemblage; and and in sulfur-containing systems were buffered by the magnetite–pyrite–pyrrhotite assemblage. Our experimental studies indicate that the species ReCl40 is dominant at 400°C in slightly acidic to near-neutral, and chloride-rich (total chloride concentrations ranging from 0.5 to 1.0 M) environments, and ReCl3+ may predominate at 500°C in a solution with total chloride concentrations ranging from 0.5 to 1.5 M. The results also demonstrate that the solubility of ReS2 is about two orders of magnitude less than that of ReO2. This finding not only suggests that ReS2 (or a ReS2 component in molybdenite) is the solubility-controlling phase in sulfur-containing, reducing environments but also implies that a mixing process involving an oxidized, rhenium-containing solution and a solution with reduced sulfur is one of the most effective mechanisms for deposition of rhenium. In analogy with Re, TcS2 may be the stable Tc-bearing phase in deep geological repositories of radioactive wastes.

Investigation of Structure and Reactivity Relationship in M-N-C Type Catalysts using Density Functional Tight Binding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Negre, Christian Francisco Andres; Gonzales, Ivana

Catalysts inhibition studies were performed to indisputably confirm the role of various metal, carbon, and nitrogen moieties in the individual steps of oxygen reduction reaction (ORR) on M-N-C catalysts. ORR activity was studied at University of New Mexico by rotating ring disk electrode method in the acidic electrolyte with the addition of Tris (tris(hydroxymethyl)-aminomethane) as inhibiting agent. To understand the interaction of Tris with different defects that exist in Fe-N-C materials and provide the support for the experimental data, we used density functional theory (DFT) and modeled the interaction of protonated Tris (TrisH) with Fe containingcenters (Fe-N 4 and Fe-Nmore » 2C 2), pyridinic nitrogen, graphitic nitrogen, and pyrrolic nitrogen both as in plane and edge defects.« less

Balance the Carrier Mobility To Achieve High Performance Exciplex OLED Using a Triazine-Based Acceptor.

PubMed

Hung, Wen-Yi; Chiang, Pin-Yi; Lin, Shih-Wei; Tang, Wei-Chieh; Chen, Yi-Ting; Liu, Shih-Hung; Chou, Pi-Tai; Hung, Yi-Tzu; Wong, Ken-Tsung

2016-02-01

A star-shaped 1,3,5-triazine/cyano hybrid molecule CN-T2T was designed and synthesized as a new electron acceptor for efficient exciplex-based OLED emitter by mixing with a suitable electron donor (Tris-PCz). The CN-T2T/Tris-PCz exciplex emission shows a high ΦPL of 0.53 and a small ΔET-S = -0.59 kcal/mol, affording intrinsically efficient fluorescence and highly efficient exciton up-conversion. The large energy level offsets between Tris-PCz and CN-T2T and the balanced hole and electron mobility of Tris-PCz and CN-T2T, respectively, ensuring sufficient carrier density accumulated in the interface for efficient generation of exciplex excitons. Employing a facile device structure composed as ITO/4% ReO3:Tris-PCz (60 nm)/Tris-PCz (15 nm)/Tris-PCz:CN-T2T(1:1) (25 nm)/CN-T2T (50 nm)/Liq (0.5 nm)/Al (100 nm), in which the electron-hole capture is efficient without additional carrier injection barrier from donor (or acceptor) molecule and carriers mobilities are balanced in the emitting layer, leads to a highly efficient green exciplex OLED with external quantum efficiency (EQE) of 11.9%. The obtained EQE is 18% higher than that of a comparison device using an exciplex exhibiting a comparable ΦPL (0.50), in which TCTA shows similar energy levels but higher hole mobility as compared with Tris-PCz. Our results clearly indicate the significance of mobility balance in governing the efficiency of exciplex-based OLED. Exploiting the Tris-PCz:CN-T2T exciplex as the host, we further demonstrated highly efficient yellow and red fluorescent OLEDs by doping 1 wt % Rubrene and DCJTB as emitter, achieving high EQE of 6.9 and 9.7%, respectively.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agnew, Douglas W.; Gembicky, Milan; Moore, Curtis E.

Here, the preparation of 3D and 2D Cu(I) coordination networks using ditopic m-terphenyl isocyanides is described. The incorporation of sterically encumbering substituents enables the controlled, solid-state preparation of Cu(I) tris-isocyanide nodes with a labile solvent ligand in a manner mirroring solution-phase chemistry of monomeric complexes. The protection afforded by the m-terphenyl groups is also shown to engender significant stability towards heat as well as acidic or basic conditions, resulting in robust single-metal-node networks that can transition from 3D to 2D extended structures.