Phosphate/citrate buffer

2008 ◽  
Vol 2008 (5) ◽  
pp. pdb.rec11328-pdb.rec11328 ◽  
Keyword(s):  
Citrate Buffer ◽  
Phosphate Citrate Buffer

Preparation of a Factor VII Concentrate

1979 ◽  
Author(s):  
A.J. MacLeod ◽  
I. Dickson
Keyword(s):  
Specific Activity ◽  
Fresh Frozen Plasma ◽  
Factor Vii ◽  
Batch Adsorption ◽  
Citrate Buffer ◽  
Linear Gradient ◽  
Fresh Frozen ◽  
Frozen Plasma ◽  
Phosphate Citrate Buffer

A factor VII concentrate has been prepared from pooled citrated fresh frozen plasma following removal of cryoprecipitate and factors II, IX and X. The method involved batch adsorption on DEAE-Sephadex A-50, fractionation of the subsequent batch eluate by PEG precipitation and passage through a column of DEAE-Sepharose CL-.6B. A phosphate-citrate buffer pH 6.9 was used throughout, this was made 0.2M with NaCl for the batch elution and a 0 - 0.2H NaCl linear gradient was used to elute the components from the column. Factor VII activity was clearly resolved from the bulk of the protein, including caeruloplasmin, and could be recovered as a concentrate at about 20 U FVII/ml with a specific activity of in excess of 1 U FVII/mg of protein and an overall recovery of 40% to 50%

Determination of fumonisins B1 and B2 in maize-based baby food products by HPLC with fluorimetric detection after immunoaffinity column clean-up

2010 ◽  
Vol 3 (2) ◽  
pp. 135-146 ◽  
Author(s):  
A. De Girolamo ◽  
D. Pereboom-de Fauw ◽  
E. Sizoo ◽  
H. van Egmond ◽  
L. Gambacorta ◽  
...  
Keyword(s):  
High Performance ◽  
Signal To Noise Ratio ◽  
Retail Market ◽  
Immunoaffinity Column ◽  
Limit Of Quantification ◽  
Citrate Buffer ◽  
Relative Standard ◽  
Phosphate Citrate Buffer ◽  
Infants And Young Children

A method for the determination of fumonisin B1 (FB1) and B2 (FB2) in different commercial maize-based products for infants and young children was developed and tested in a limited validation study involving 3 laboratories. The method used extraction at 55 °C with an acidic mixture of methanol-acetonitrile-phosphate/citrate buffer, clean-up through immunoaffinity column and fumonisin determination by high performance liquid chromatography with automated pre-column derivatisation with o-phthaldialdehyde. Recovery experiments were performed at five spiking levels in the ranges of 80-800 µg/kg FB1 and 20-200 µg/kg FB2. Mean recoveries ranged from 83 to 97% for FB1 and from 61 to 78% for FB2. Relative standard deviations for within-laboratory repeatability (RSDr) ranged from 5 to 12% for FB1 and from 8 to 13% for FB2, whereas relative standard deviation for between-laboratory reproducibility (RSDR) ranged from 6 to 10% for FB1 and from 9 to 16% for FB2. The limit of quantification of the method (signal to noise ratio of 6) was 2.8 µg/kg for FB1 and 2.2 µg/kg for FB2. Fumonisins were found in 6 out of 19 maize-based baby foods obtained from the Italian retail market at levels up to 53 µg/kg.

THE LYSIS OF ACETOBACTER XYLINUM

1962 ◽  
Vol 8 (6) ◽  
pp. 841-846 ◽  
Author(s):  
T. E. Webb ◽  
J. Ross Colvin
Keyword(s):  
Cell Population ◽  
Local Area ◽  
Oxidative Capacity ◽  
Acetobacter Xylinum ◽  
Sensitive Species ◽  
Citrate Buffer ◽  
Whole Cells ◽  
Size And Shape ◽  
Phosphate Citrate Buffer

Lysis of about 90% of the cells of Acetobacter xylinum by lysozyme may be obtained after 2 hours at pH 8.1 in phosphate–citrate buffer. The cell population is heterogeneous since the remaining 10% of the cells do not lyse, even on repetition of the above treatment. The lysozyme does not cause the dissolution of all the bacterial wall, as in other lysozyme-sensitive species, but appears to attack only a limited, local area on the surface of the bacterium. Following the local weakening of the wall, the cell contents escape into the medium leaving a distinct "hull" with the same size and shape as the cell. The oxidative capacity of the lysed cells is the same as that of the whole cells. Reasons for the heterogeneity of the bacterial wall, both within and between cells, remain obscure.

scholarly journals A rapid method to determine the bactericidal activity of compounds against non-replicatingMycobacterium tuberculosisat low pH

2019 ◽  
Author(s):  
Julie V. Early ◽  
Steven Mullen ◽  
Tanya Parish
Keyword(s):  
Bactericidal Activity ◽  
Minimum Bactericidal Concentration ◽  
Treatment Time ◽  
Low Ph ◽  
Citrate Buffer ◽  
Colony Forming Units ◽  
Carbonyl Cyanide ◽  
Viable Bacteria ◽  
Phosphate Citrate Buffer ◽  
Assay Conditions

AbstractThere is an urgent need for new anti-tubercular agents which can lead to a shortened treatment time by targeting persistent or non-replicating bacilli. In order to assess compound activity against non-replicatingMycobacterium tuberculosis, we developed a method to detect the bactericidal activity of novel compounds within 7 days. Our method uses incubation at low pH in order to induce a non-replicating state. We used a strain ofM. tuberculosisexpressing luciferase; we first confirmed the linear relationship between luminescence and viable bacteria (determined by colony forming units) under our assay conditions. We optimized the assay parameters in 96-well plates in order to achieve a reproducible assay. Our final assay usedM. tuberculosisin phosphate-citrate buffer, pH 4.5 exposed to compounds for 7 days; viable bacteria were determined by luminescence. We recorded the minimum bactericidal concentration at pH 4.5 (MBC4.5) representing >2 logs of kill. We confirmed the utility of the assay with control compounds. The ionophores monensin, niclosamide, and carbonyl cyanide 3-chlorophenylhydrazone and the anit-tubercular drugs pretomanid and rifampicin were active, while several other drugs such as isoniazid, ethambutol, and linezolid were not.

scholarly journals Estudo do comportamento eletroquímico da enzima peroxidase na presença de peróxido de hidrogênio e ácido 5- aminossalicílico

2018 ◽  
Vol 33 (1) ◽  
pp. 57
Author(s):  
Carolina Venturini Uliana ◽  
Carla Dos Santos Riccardi ◽  
Hideko Yamanaka
Keyword(s):  
Hydrogen Peroxide ◽  
Electrochemical Behavior ◽  
Oxidation Reaction ◽  
Supporting Electrolyte ◽  
Aminosalicylic Acid ◽  
Applied Potential ◽  
Cathodic Current ◽  
Citrate Buffer ◽  
Graphite Electrodes ◽  
Phosphate Citrate Buffer

The electrochemical behavior of the enzyme peroxidase (HRP) was investigated using the hydrogen peroxide as enzymatic substrate and the 5-aminosalicylic acid (5-ASA) as mediator of electrons on graphite electrodes. Several parameters were optimized, namely, the applied potential to the amperometric technique fixed in -0.125V, the 0.1 mol L-1 phosphate-citrate buffer at pH 5.0 as supporting electrolyte and the proportion between the 5-ASA and H2O2 in 1:7, among others. It was observed the catalysis of the oxidation reaction of the H2O2 in the presence of the enzyme HRP and 5-ASA. The oxidation product was reduced in the electrode surface, evidencing a significant increase in the intensity of the cathodic current.

scholarly journals Fungicidal mechanism of action of D0870 against Cryptococcus neoformans under acidic conditions.

1997 ◽  
Vol 41 (12) ◽  
pp. 2710-2713 ◽  
Author(s):  
H Yamada ◽  
T Watanabe ◽  
K Kato ◽  
H Mochizuki
Keyword(s):  
Cell Membrane ◽  
Cryptococcus Neoformans ◽  
Ergosterol Biosynthesis ◽  
Spectrometric Analysis ◽  
Citrate Buffer ◽  
Unknown Lipid ◽  
Marked Accumulation ◽  
Acidic Conditions ◽  
Phosphate Citrate Buffer ◽  
Chromatographic Mass

The fungicidal mechanism of the triazole D0870 against Cryptococcus neoformans under acidic conditions was investigated. D0870 reduced the intracellular K+ content of C. neoformans at pH 4 to about half the value at pH 7 after 12 h of incubation. The 50% inhibitory concentrations of D0870 for ergosterol biosynthesis were almost the same at both pH 4 (0.017 microg/ml) and 7 (0.014 microg/ml); however, D0870 caused a marked accumulation of an unknown lipid and methylated sterols in C. neoformans cultured at pH 4. Extracted fractions containing the unknown lipid or methylated sterols showed strong fungicidal activities against C. neoformans both at pH 4 and 7 in phosphate-citrate buffer not containing D0870. Gas chromatographic-mass spectrometric analysis showed that the unknown lipid was obtusifolione. These results suggest that D0870 kills C. neoformans by disturbing the permeability of the cell membrane through the accumulation of obtusifolione and methylated sterols in the cell membrane under acidic conditions.

scholarly journals WATER-SOLUBLE POLYMERIC IONIC 5-FLUOROURACIL COMPLEX BASED ON METHACRYLIC ACID COPOLYMERS

2019 ◽  
pp. 214-219
Author(s):  
Olga Zhukova ◽  
SERGEY A. RYABOV ◽  
SERGEY D. ZAITSEV ◽  
OLGA V. KUZNETSOVA ◽  
DARIA M. GAVRILOVA ◽  
...  
Keyword(s):  
Particle Size ◽  
Methacrylic Acid ◽  
Phosphate Buffer ◽  
Water Soluble ◽  
Butyl Methacrylate ◽  
Polymeric Complex ◽  
Polymeric Carrier ◽  
Citrate Buffer ◽  
Intracellular Space ◽  
Phosphate Citrate Buffer

Objective: The objective of this work was to obtain a water-soluble 5-fluorouracil (5-FU) polymeric complex on the basis of a methacrylic acid (MAA) copolymer to be used as an injectable chemotherapeutic agent. Methods: A polymeric carrier was synthesized using tert-butyl methacrylate (TBMA) as a monomer, thioglycolic acid, and azobisisobutyronitrile as a radical polymerization initiator. The polymer was converted by acid hydrolysis into a water-soluble copolymer of TBMA and MAA of 20: 80 mass%, respectively. The copolymer of TBMA and MAA was modified with 5-FU. Their formation was proved using IR and UV spectroscopy. The particle size of the 5-FU polymeric complex was estimated by turbidimetry, which is based on measuring the intensity of light transmitted through a disperse system. The release of 5-FU from the obtained ionic complexes by dialysis in vitro was evaluated. Results: Polymeric carriers were obtained with different amounts of 5-FU (5, 15, 25, 50 mol%). A high peak at λ = 266 nm was observed in the UV spectrum of the polymeric carrier (characteristic of 5-FU). The particle size was estimated at 13 nm for the complex with 5 mol% 5-FU and 26.8 n for the complex with 50 mol% 5-FU. The 5-FU release was estimated in two parallel experiments at 37 °C. One utilized a phosphate-citrate buffer with pH 5.0 to model the intracellular space and the other, a phosphate buffer with pH 7.4 to model the intravascular space. Two systems, with 5 and 15 mol% 5-FU, were chosen for testing. In both phosphate buffer and phosphate-citrate buffer, 5-FU was released from the polymeric complex with 5 mol% 5-FU approximately 1.3 times faster than from the complex containing 5 mol% 5-fluorouracil. The kinetics of 5-FU release from the polymeric complex (5 mol% 5-fluorouracil) showed that the 5-FU release was 77.9% in phosphate-citrate buffer and 59.6% in phosphate buffer over 52 h of dialysis. When the 5-FU release kinetics was studied with the polymeric complex containing 15 mol% 5-FU, the 5-FU release was 100.0% in phosphate-citrate buffer and 75.1% in phosphate buffer over 57 h of dialysis. Conclusion: Water-soluble nanoscale complexes of 5-FU with TBMA–MAA copolymers extend application of 5-FU, while its general toxicity might be lower. The complexes are sufficiently stable at pH 7.4 and readily release 5-FU at pH 5.0.

Autoantibodies to Thrombomodulin: Development of an Enzyme Immunoassay and a Survey of their Frequency in Patients with the Lupus Anticoagulant

1992 ◽  
Vol 67 (05) ◽  
pp. 507-509 ◽  
Author(s):  
John Gibson ◽  
Margaret Nelson ◽  
Ross Brown ◽  
Hatem Salem ◽  
Harry Kronenberg
Keyword(s):  
Enzyme Immunoassay ◽  
Lupus Anticoagulant ◽  
Specific Binding ◽  
Technical Problem ◽  
Serum Samples ◽  
Citrate Buffer ◽  
The Mean ◽  
Sample Dilution ◽  
Negative Population ◽  
Serum Components

SummaryIn order to investigate the possibility that autoantibodies to thrombomodulin (TM) may exist in patients with the lupus anticoagulant (LA) and perhaps be implicated in the pathogenesis of recurrent thrombosis seen in such patients, we developed an enzyme-immunoassay to screen serum samples for anti-human TM activity. The major technical problem encountered in developing this assay was to reduce the non-specific binding of serum components from both the LA positive and the negative population. Considerable reduction of non-specific binding was achieved by use of a phosphate/citrate buffer at pH 8.0 and the use of an optimal sample dilution of 1/40. In addition, samples were always tested in parallel in blank wells and results are expressed as an OD ratio. Samples from 113 patients with the LA were assayed and compared to 78 patients referred for LA testing but found to be negative. The mean OD values for the LA positive patients (± SD) was 1.36 (0.44) with a range of 0.78-2.57. This was virtually identical to the values for the LA negative population (1.38 ± 0.40, range 0.76-2.77). The results of this study indicate that there is no evidence for the presence of a significant autoantibody activity to TM in patients with the LA when compared to LA negative patients. If such autoantibodies do exist their frequency must be quite low.

scholarly journals Optimization of a Method for Extraction and Determination of Residues of Selected Antimicrobials in Soil and Plant Samples Using HPLC-UV-MS/MS

2021 ◽  
Vol 18 (3) ◽  
pp. 1159
Author(s):  
Klaudia Kokoszka ◽  
Agnieszka Kobus ◽  
Sylwia Bajkacz
Keyword(s):  
Nalidixic Acid ◽  
High Performance ◽  
Solid Phase ◽  
Sewage Treatment ◽  
Animal Manure ◽  
Uv Detector ◽  
Citrate Buffer ◽  
High Biological Activity ◽  
Extraction Solvent

The residues of antimicrobials used in human and veterinary medicine are popular pollutants of anthropogenic origin. The main sources of introducing antimicrobials into the environment are sewage treatment plants and the agricultural industry. Antimicrobials in animal manure contaminate the surrounding soil as well as groundwater, and can be absorbed by plants. The presence of antimicrobials in food of plant origin may pose a threat to human health due to their high biological activity. As part of the research, a procedure was developed for the extraction and determination of ciprofloxacin, enrofloxacin, cefuroxime, nalidixic acid and metronidazole in environmental samples (soil and parsley root). An optimized solid-liquid extraction (SLE) method was used to separate antimicrobials from the solid samples and a mixture of citrate buffer (pH = 4): methanol (1:1; v/v) was used as the extraction solvent. Solid phase extraction (SPE) with OASIS® HLB cartridges was used to purify and pre-concentrate the sample. The recovery of the developed method was in the range of 55–108%. Analytes were determined by high-performance liquid chromatography coupled with an ultraviolet (UV) detector and a tandem mass spectrometer (HPLC-UV-MS/MS). The procedure was validated and applied to the determination of selected antimicrobials in soil and parsley root samples. Five types of soil and five types of parsley roots of different origins were analyzed. The presence of nalidixic acid in the parsley root samples was found in the concentration range of 0.14–0.72 ng g−1. It has been shown that antimicrobials are absorbed by the plant and can accumulate antimicrobials in its edible parts.

Sign in / Sign up

Export Citation Format

Share Document