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At least 1,423 records · Page 79Linked to original sources
PubMed1984

Ammonium sulphate precipitation overestimates titres of anti-peptide antisera.

Precipitation by 50% final saturation of ammonium sulphate, a method commonly used to estimate titres and affinity constants of antibodies, was found consistently to overestimate the titre of anti-peptide antisera when compared with other antibody precipitants. The effect could not be attributed to non-IgG fractions, and similar overestimations were found when pure IgG was used. We suggest that the lower values represent a more physiologically relevant estimation.

Ammonium Sulfate↗
PubMed1986

Detection of antigen in immune precipitates by silver staining of SDS-polyacrylamide gels.

The silver staining technique of Merril et al. (1981) was used to identify antigens separated by SDS-PAGE after dissociation of immune complexes purified by absorption with staphylococcus A protein. The five and four dominating structural components of measles and RS virus (Mr range 28,000 to 79,000) respectively precipitated with monoclonal antibodies were readily identified, except when the Mr of the virus-specific antigen was in the same range as immunoglobulin heavy and light chains. Specific antigens were identified less effectively after precipitation with polyclonal sera because of a larger background of stainable proteins. This method, which combines the sensitivity and high resolution of silver staining and the specificity of immune complexing with monoclonal antibodies, is rapid and inexpensive.

Antibodies, Monoclonal↗
PubMed1990

Comparison of polyethylene glycol precipitation and ultracentrifugation for recovery of cytomegalovirus from urine prior to detection of DNA by dot-blot hybridisation.

Polyethylene glycol (PEG) precipitation provided a useful alternative to ultracentrifugation for recovering cytomegalovirus (CMV) from clinical specimens prior to DNA hybridisation studies. The conditions for use of PEG are described. In a study of 61 urine samples from patients suspected of CMV infection 18 yielded a positive DNA hybridisation result. Fifteen were positive after both concentration procedures, two after PEG precipitation only and one after ultracentrifugation only. The DNA hybridisation results are discussed in the light of the results of virus isolation by cell culture.

Chemical Precipitation↗
PubMed1982

Drug-induced oxidation and precipitation of hemoglobins A, S and C.

Analysis of optical absorption spectra of drug-hemoglobin reaction mixtures show that oxidation of oxyhemoglobins A, S and C by menadione and acetylphenylhydrazine and the consequent formation of methemoglobin, hemichromes and 'choleglobin' proceed at identical rates for all three hemoglobins. Nevertheless, precipitate formation, which is linked to hemichrome production, occurs in a definite order: S greater than C greater than A. Differences in precipitability among these three hemoglobins are linked to an as yet unidentified property of the aggregate hemichromes, which is not directly related to the rate of total hemichrome production.

Chemical Precipitation↗
PubMed1985

Purification of liver glutamate dehydrogenase by affinity precipitation and studies on its denaturation.

In the presence of glutaric acid, N2,N2'-adipodihydrazido-bis(N6-carbonylmethyl-NAD+)(bis-NAD+ ) forms cross-links between molecules of glutamate dehydrogenase, resulting in precipitation. The dependence of this process on bis-NAD+ and enzyme concentration has been investigated. This procedure has been shown to be effective in the purification of glutamate dehydrogenase from rat and ox liver, and a procedure is presented in which this affinity precipitation procedure is used instead of the affinity chromatography used in an earlier method (McCarthy, A.D., Walker, J.M. and Tipton, K.F. (1980) Biochem. J. 191, 605-611). The ox liver enzyme prepared in this way had not suffered the limited proteolysis that occurs during the preparation of the enzyme by other commonly used procedures. After the purified enzyme had been denatured by treatment with urea, guanidine hydrochloride, or low pH, no recovery of activity could be demonstrated following dilution or, in the last case, dialysis.

Affinity Labels↗
PubMed1978

Studies on lectins. XXXV. Water-soluble O-glycosyl polyacrylamide derivatives for specific precipitation of lectins.

By copolymerization of acrylamide and allyl glycosides of various sugars, O-glycosyl derivatives of polyacrylamide copolymers were prepared. The sugar content of the copolymers can be varied in the range 0--40%, their sedimentation coefficient shows the vales of 2.5-5.7 S; the molecular weight of an O-alpha-D-mannopyranosyl polyacrylamide copolymer (29% mannose, so20,w = 2.9 S) was estimated as 44 500. Copolymers with incorporated glycosyl residues interacting specifically with lectins yield precipitates with them upon immunodiffusion in cellulose acetate. The quantitative precipitin curves obtained with these copolymers are similar to those produced by quantitative precipitation of lectins with natural polysaccharides. The copolymers may serve as model substances of natural polysaccharides.

Acrylamides↗
PubMed1979

Precipitation of animal plasma proteins by puff-adder venom.

1. Plasma and serum samples obtained from various animals never previously exposed to snakes or snake venom were diffused against different concentrations of puff-adder, Bitis arietans, venom using the double immunodiffusion technique. 2. Depending upon venom concentration, two precipitin arcs could be produced in the case of all plasma samples used. No serum samples showed any arcs except pigeon serum, where one precipitin line was observed. 3. By altering the concentration of snake venom between 1% and 10% when immunodiffusing against plasma a change in position of the precipitin lines was observed and also the disappearance of one or both of the two bands at higher concentrations. This indicates that the arcs observed are in all probability due to precipitation of plasma protein fractions. 4. Previous results indicated that one of the two bands observed when diffusing venom against plasma was due to the precipitation of fibrinogen. By diffusing snake venom against heparin we have now shown that the second band involves this molecule and is not due to another coagulation factor as was suggested previously.

Animals↗
PubMed1986

Phosvitin isolation from fish eggs: methodological improvements including 'specific' phosvitin precipitation with ferric ion.

Modifications of the method of Wallace et al. [Can. J. Biochem. 44, 1647-1655 (1966)] for phosvitin isolation from vertebrate eggs were devised to enhance the method's general effectiveness. Phosvitins which do not precipitate on dilution from solutions of their lipovitellin complexes may be selectively adsorbed onto, and desorbed from, DEAE-cellulose. Phosvitins which are too small for dialysis or ultrafiltration may be concentrated or desalted by precipitation with stoichiometric amounts of ferric ions, followed by iron removal with EDTA on gel filtration. Since phosvitin distribution among ammonium sulfate fractions depends on initial protein and salt concentrations in a species-specific manner, pilot experiments are needed to establish conditions for optimal fractionation.

Amino Acids↗
PubMed1996

Protein partition between the different phases comprising poly(ethylene glycol)-salt aqueous two-phase systems, hydrophobic interaction chromatography and precipitation: a generic description in terms of salting-out effects.

The solution behaviour of selected proteins has been studied under conditions promoting precipitation, binding to mildly hydrophobic adsorbents or partition. Solvophobic theory may be used to describe these forms of protein partition. The tendency of a protein to partition therein is dependent upon surface properties of the protein solute mediated by the concentration and nature of added salts. As applied to partitioning in poly(ethylene glycol) (PEG)-salt systems this implies that linear (Brönsted) relationships apply only to proteins partitioned close to the critical point. At longer tie-line lengths protein partitioning is increasingly influenced by salting-out forces. This is confirmed by the observed behaviour of the proteins. The point at which this behaviour changes has been unambiguously defined enabling the direct comparison of phase transition of proteins during partition in all systems. The results obtained show that phase transition during adsorption and partition occur at similar concentrations of salt. This is less than that required to promote precipitation. It appears, from these limited studies, that top-phase preferring proteins are partitioned at salt concentrations above those required to cause adsorption. Proteins preferring the lower phase are partitioned at salt concentrations close to or below those required for adsorption. This raises questions regarding the solvated molecular form of the partitioned proteins and the definition of the partition coefficient.

Chemical Precipitation↗
PubMed1989

Application of scanning electron microscopy and energy-dispersive X-ray analysis to the solution behaviour of Zn-insulin: precipitation phenomena.

Scanning electron microscopy (SEM) has been applied in combination with energy dispersive X-ray analysis (EDAX) to identify and analyse particles or particulate matter, occasionally present in clear neutral Zn-insulin solutions. SEM photographs revealed the existence of three different types of precipitate, consisting of particles with a crystalline, amorphous or gel-like nature, respectively. At present, it is not clear which conditions lead specifically to each of these three types of precipitate. The advantages of the EDAX method are shown. The technique enables semi-quantitative analysis to be performed on a single particle as small as 0.2 microns. It was demonstrated with the EDAX method that the particles occasionally found in clear Zn-insulin solutions contain insulin as well as Zn in roughly the same ratio as in the insulin starting material. It is concluded that the EDAX method has great potential in pharmaceutical technology, inter alia for the analysis of emulsion systems (in the frozen state), as well as suspensions and particulate matter in injection fluids. This technique is particularly useful in the latter case, due to its applicability to extremely small sample sizes.

Animals↗
PubMed1994

Determination of papaverine and cocaine by use of a precipitation system coupled on-line to an atomic absorption spectrometer.

A continuous-precipitation flame-atomization atomic absorption spectrometric method for the determination of papaverine and cocaine hydrochlorides is proposed. The method is based on the precipitation of reineckates by injection of Reinecke's salt into a carrier containing the alkaloids and their subsequent retention on a stainless steel filter. In this way, papaverine and cocaine hydrochlorides can be determine over the ranges 5-85 and 50-850 micrograms ml-1 with a relative standard deviation of 1.3 and 3.2%, respectively, and a sampling frequency of 150 h-1. The proposed method is more sensitive and selective for papaverine than it is for cocaine and can be applied to the determination of papaverine HCl in pharmaceutical preparations.

Chemical Precipitation↗
PubMed1995

Degradation of lyophilized and reconstituted MACROSCINT (DTPA-IgG): precipitation vs. glucosylation.

Diethylenetriaminepentaacetic anhydride (DTPA) conjugated to IgG (DTPA-IgG) and labeled with 111In is useful for detecting focal sites of infection and inflammation (R.H. Rubin, A.J. Fischman, R.J. Callahan, B. Khaw, F. Keech, M. Ahmad, R. Wilkinson and H.W. Strauss, 111In-labeled nonspecific immunoglobulin scanning in the detection of focal infection, N. Engl. J. Med., 321 (1989) 935-940). MACROSCINT contains DTPA-IgG formulated as a lyophile from a citrate buffer containing maltose. Exposure of both reconstituted and lyophilized MACROSCINT to intense light resulted in degradation primarily via formation of precipitating aggregates. However, lyophilized and reconstituted MACROSCINT responded differently to thermal stress. Reconstituted MACROSCINT subjected to thermal stress (65 degrees C) also degraded through formation of precipitating aggregates. In contrast, exposure of lyophilized MACROSCINT to thermal stress (65 degrees C) resulted primarily in an increase in the molecular size of the MACROSCINT DTPA-IgG monomer. This increase in molecular size was a function of both the moisture content in the vial and the amount of time for which the sample was stressed, but was not a function of the conjugation with DTPA. Monosaccharide analysis of the samples demonstrated that this increase in molecular size corresponded to an increase in the amount of glucose covalently attached to the IgG. These data suggest that the increase in molecular size as a function of thermal stress is due to the covalent attachment of maltose, which is a glucose disaccharide present in the lyophile as an excipient, to the IgG. This degradation pathway was only observed in the lyophile.

Chemical Precipitation↗
PubMedDate not supplied

[Differentiation of Yersinia enterocolitica 0:3 and 0:9 by precipitation of CaCO3 at 37 degrees C].

Precipitation of CaCO3 by different Yersinia strains on B-4 agar at 25 and 37 degrees C was studied. The 185 Yersinia strains examined produced crystals at 25 degrees C, but only 121 strains produced crystal at 37 degrees C. Strains of serotype 0:9 produced crystals at 37 degrees C, whereas strains of serotype 0:3 failed to do so. The calcium carbonate precipitation test at 37 degrees C should enable a differentiation between the two serotypes incriminated in human pathology in Europe.

Calcium Carbonate↗
PubMed2004

TEM study of calcium phosphate precipitation on bioactive titanium surfaces.

Formation of calcium phosphate on alkali- and heat-treated titanium surfaces was investigated using transmission electron microscopy (TEM). The samples were prepared by immersing the alkali- and heat-treated titanium in a revised simulated body fluid (R-SBF) with the same HCO(3)(-) concentration level as in human blood plasma. The deposition and precipitation on treated titanium surfaces were extracted for TEM examination without thinning process. Electron diffraction of the precipitates revealed that octacalcium phosphate (OCP), instead of hydroxyapatite (HA), directly nucleates from amorphous calcium phosphate. The OCP crystals continuously grew on the titanium surfaces rather than transforming into apatite. Calcium titanate was also identified by electron diffraction. Its role in the formation bioactive calcium phosphate, however, is not clear from this experiment.

Biomimetic Materials↗
PubMed2004

Comparison of protein precipitation methods for sample preparation prior to proteomic analysis.

Protein samples should be free of salt and other disturbing agents and have an appropriate concentration to be suitable for two-dimensional (2D) electrophoresis, the principal step of proteomics. To find the most efficient method for sample preparation, we used human plasma and compared four widely applied precipitation methods, using trichloroacetic acid (TCA), acetone, chloroform/methanol and ammonium sulfate, as well as ultrafiltration. Precipitation with TCA and acetone and ultrafiltration resulted in an efficient sample concentration and desalting. We also found that ammonium sulfate fractionation can efficiently remove albumin, which represents more than 50% of plasma proteins.

Ammonium Sulfate↗
PubMed2004

Nisin-loaded poly-L-lactide nano-particles produced by CO2 anti-solvent precipitation for sustained antimicrobial activity.

Nisin-loaded poly-L-lactide (PLA) nano-particles were fabricated by processing protein/polymer organic solutions by semi-continuous compressed CO2 anti-solvent precipitation. Preliminary solubility studies were carried out for an optimised selection of organic solvent mixtures leading to preparation of protein/polymer solutions. The particles were prepared by processing 50:50 dimethylsulfoxide/dichloromethane mixtures containing 1% polymer (w/v) and 5 or 20% nisin (nisin/polymer, w/w). Proper operative conditions (organic solution injection rate, precipitation temperature and gas pressure, CO2 flow rate, washing time, etc.) were set up to yield production reproducibility, high product recovery (over 70%) and high drug loading (over 95% of the recovered protein). Scanning electron microscopy demonstrated that spherical, smooth surfaced particles were produced. Light scattering showed that the particle size was in the range of 200-400 nm and the products were characterised by narrow polydispersity. In vitro release studies showed that the protein is slowly released throughout 1000 h. However, the release was slower as the salt concentration and the pH of the release buffer increased. Solubility investigations suggested that the observed differences in protein release rate out of nano-particles was attributable to the protein interaction with the polymer which was found to increase as the pH or the salt concentration increased in the release buffer. In vitro studies carried out by nano-particle incubation in medium containing Lactobacillus delbrueckeii showed that nisin was released in the active form and the antibacterial activity was maintained up to 45 days incubation.

Carbon Dioxide↗
PubMed2005

Use of compressed gas precipitation to enhance the dissolution behavior of a poorly water-soluble drug: generation of drug microparticles and drug-polymer solid dispersions.

The classical anticonvulsant drug phenytoin (5,5-diphenyl hydantoin, C(15)H(12)N(2)O(2)) has been used as a model compound to investigate the possibility of enhancing the dissolution rate of poorly water-soluble drugs using dense gas antisolvent techniques. In a first step, microcrystals of neat phenytoin have been generated using the gas antisolvent (GAS) and precipitation with compressed antisolvent (PCA) processes, thereby assessing process performances and elucidating similarities and differences between the two techniques. In a second step, the PCA process has been used to generate solid dispersions of phenytoin in the hydrophilic polymer poly(vinyl-pyrrolidone)-K30 (PVP). In vitro dissolution results reveal a substantially better performance of the PCA-processed co-formulations compared to unprocessed phenytoin and to GAS- and PCA-precipitates of neat drug crystals. A comparison of the product quality of phenytoin-PVP co-formulations with solid dispersions obtained by spray drying convincingly underlines the potential of dense gas antisolvent techniques for the production of pharmaceutical formulations with enhanced oral bioavailability.

Chemical Precipitation↗
PubMed2006

Production of salbutamol sulfate for inhalation by high-gravity controlled antisolvent precipitation.

The purpose of this study was to produce salbutamol sulfate (SS) as a model anti-asthmatic drug using high-gravity controlled precipitation (HGCP) through antisolvent crystallisation. An aqueous solution of SS was passed through a HGCP reactor with isopropanol as antisolvent to induce precipitation. Spray drying was employed to obtain dry powders. Scanning electron microscopy, X-ray powder diffraction (XRD), density measurement, thermal gravimetric analysis, and dynamic vapour sorption were carried out to characterise the powder physical properties. The aerosol performance of the powders was measured using an Aeroliser connected to a multiple stage liquid impinger operating at 60 L/min. The HGCP SS particles were elongated with 0.1 microm in width but varying length of several mum, which formed spherical agglomerates when spray dried. The particles showed the same XRD pattern and true density (1.3g/cm3) as the raw material, indicating that they belonged to the same crystalline form. However, the spray dried agglomerates had a much lower tapped density (0.1g/cm3) than the raw material (0.6g/cm3). Compared with the powder obtained by spray drying directly from an aqueous solution, the SS powders obtained from HGCP were much less hygroscopic (0.6% versus 10% water uptake at 90% RH). The in vitro aerosol performance showed a fine particle fraction FPFloaded and FPFemitted up to 54.5+/-4.9% and 71.3+/-10.0%, respectively. In conclusion, SS powder with suitable physical and aerosol properties can be obtained through antisolvent HGCP followed by spray drying.

Aerosols↗