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At least 487 records · Page 27Linked to original sources

PubMed1976

Surface immune precipitation: a new method for rapid quantitative antigen analysis.

A new method for quantitative antigen analysis is described which precludes necessity for long incubation periods. The new technique, Surface Immune Precipitation (SIP), entails the application of an antigen sample droplet directly onto the surface of a gel containing antibody, the gel being supported by a reflecting substrate. Within a few minutes, a visible uniform opaque precipitate area appears at the location of the antigen droplet when antigen-specific antibody is present in the gel. The reflecting substrate enhances the contrast between the precipitate area and the surrounding gel. The scattering intensity of the precipitate, which may be measured with simple photodetection apparatus, is related to the antigen concentration in the droplet. Good correlation is demonstrated between the Surface Immune Precipitation method and radial immunodiffusion for the analysis of serum IgG.

Agar↗

PubMed1989

Effect of temperature on the sodium sulphite precipitation test for assessment of goat serum immunoglobulin.

Total serum immunoglobulin concentrations of apparently normal indigenous goats were estimated by a sodium sulphite precipitation test which utilized 3 concentrations of the salt (i.e. 14%, 16%, 18%). A total of 210 goat serum samples comprising five phenotypically different breeds were examined. Immunoglobulin precipitation was greatly influenced by the incubation temperature. Using different concentrations of the sodium sulphite salt solution, serum samples incubated at either 4 degrees C or 38 degrees C consistently gave clear and rapid precipitation reaction in all samples with immunoglobulin concentrations of over 15 mg/ml. Tests carried out at normal tropical room temperature (28 degrees-30 degrees C) gave inconsistent results and only 52% gave clear precipitation. Neither breed nor sex had any statistically significant effect on either the precipitation rate or the immunoglobulin values (P less than 0.05). It was concluded that this test if performed at either 4 degrees C or 38 degrees C can be used under field conditions to evaluate immune status of neonatal goats in the tropics.

Animals↗

PubMed1985

Calcium precipitation from mammalian physiological salines (Ringer solutions) and the preparation of high [Ca] media.

The maximum nonprecipitating concentration of calcium in a bicarbonate-buffered Krebs-Henseleit-type mammalian physiologic saline at 25 degrees C has been established as 10 mM in the presence of 1 mM phosphate, and as 18 mM when phosphate is absent. At 38 degrees C, the respective limits are 5.6 mM with the phosphate, and 16 mM in its absence. At its physiological concentration of 1.6 mM, calcium precipitation also appeared in solutions of pH greater than 9. When phosphate was present, the precipitate appeared immediately, but redissolved once pH was reduced below 7.8; in the absence of phosphate, precipitation of calcium carbonate became visible only after 3-4 min, but this precipitate would not redissolve even at pH 7.4. As carbonated stock bicarbonate solution gradually loses CO2 and becomes alkaline, a protocol for mixing physiologic salines using alkaline bicarbonate stock was developed. Calcium precipitation can be avoided if, before calcium is added, the bicarbonate-containing bulk solution is gassed with 5% CO2 for 15 min at a flow of 0.5 liter/min per liter of final solution.

Calcium↗

PubMed1991

Secondary structure perturbations in salt-induced protein precipitates.

The secondary structure implications of precipitation induced by a chaotropic salt, KSCN, and a structure stabilizing salt, Na2SO4, were studied for twelve different proteins. alpha-helix and beta-sheet content of precipitate and native structures were estimated from the analysis of amide I band Raman spectra. A statistical analysis of the estimated perturbations in the secondary structure contents indicated that the most significant event is the formation of beta-sheet structures with a concomitant loss of alpha-helix on precipitation with KSCN. The conformational changes for each protein were also analyzed with respect to elements of primary, secondary and tertiary structure existing in the native protein; primary structure was quantified by the fractions of hydrophobic and charged amino acids, secondary structure by x-ray estimates of alpha-helix and beta-sheet contents of native proteins and tertiary structure by the dipole moment and solvent-accessible surface area. For the KSCN precipitates, factors affecting beta-sheet content included the fraction of charged amino acids in the primary sequence and the surface area. Changes in alpha-helix content were influenced by the initial helical content and the dipole moment. The enhanced beta-sheet contents of precipitates observed in this work parallel protein structural changes occurring in other aggregative phenomena.

Chemical Precipitation↗

PubMed1989

Precipitating antibodies of the duck (Anas platyrhynchos).

1. Ducks do not usually produce precipitating antibodies. However, when hyperimmunized with the dinitrophenyl (DNP)-human IgG (HIgG) conjugate, ducks made precipitating antibodies to the HIgG carrier, though not to the DNP hapten. 2. Precipitation did not require NaCl and occurred over a wide range of molarities and pH. 3. Antigenic and polyacrylamide gel analysis of affinity-purified antibodies, indicated that the major constituent of the antibody population was electrophoretically homogeneous 5.7S IgG. 4. The Ig heavy chains were in two populations, viz MW 37,000 and 41,000; non-precipitating duck 5.7S IgG antibodies to HIgG had only the MW 37,000 heavy chains. 5. It is suggested that duck precipitins belong to a previously unrecognized subclass of duck 5.7S IgG, with minor physical and antigenic differences from their non-precipitating counterparts.

Animals↗

PubMed1995

Comparative study on brush border membranes prepared from rat and monkey small intestine by Ca2+ and Mg2+ precipitation.

Brush border membranes, prepared by Ca2+ or Mg2+ precipitation, from monkey or rat small intestine were compared for marker enzyme enrichment and lipid composition. Membranes prepared from rat intestine by Mg2+ precipitation were less pure in terms of their marker enzyme enrichment than Ca2+ precipitated membranes. Moreover, Mg2+ precipitated membranes were contaminated by basolateral membranes as evidenced by the enrichment of Na(+)-K+ ATPase. The content and composition of phospholipids were different in Mg2+ and Ca2+ precipitated membranes. The membranes prepared by the two methods from monkeys were identical in their marker enzyme enrichment and lipid composition and unlike those obtained from the rat, there was no basolateral membrane contamination.

Alkaline Phosphatase↗

PubMed2006

Precipitation of calcium phosphate and calcium carbonate induced over chitosan membranes: a quick method to evaluate the influence of polymeric matrices in heterogeneous calcification.

Precipitation of calcium compounds (phosphate and carbonate) was performed on chitosan porous and dense membranes. In order to observe the influence of acetyl groups on the nature of formed precipitates, some chitosan membranes were acetylated in methanol solution before undergoing calcification. Calcification experiments were performed more quickly than using SBF. In this method, a faster precipitation is induced by soaking the membranes in calcium chloride solutions and, in sequence, immersing the same membranes into sodium phosphate or carbonate solutions. This procedure induced the formation of calcium compound precipitates on membrane surfaces, which were analysed through optical microscopy, X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy with attenuated total reflection apparatus (FTIR-ATR) and small angle X-ray scattering (SAXS). The results indicated the biomimetic influence of the organic matrix on morphology, organization and composition of precipitates. The acetyl group induced the formation of organized calcium carbonate better than phosphate, which may correlate with the fact that these two compounds are commonly found together in nature in structures like shells and nacre.

Calcium Carbonate↗

PubMed2006

Integrity and stability studies of precipitated rhBMP-2 microparticles with a focus on ATR-FTIR measurements.

A major obstacle in the development of protein drug formulations is the need to maintain the native, active protein structure both during the formulation process and upon long time storage. Controlled precipitation was evaluated for its potential to supply stable microparticulate formulations of bone-regenerating recombinant human Bone Morphogenetic Protein-2 (rhBMP-2). Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) did provide insight into the protein formulation and stability. Temperature dependent ATR-FTIR measurements and DSC measurements allow for the study of changes in the protein structure during melting. To address the question of isomerization, peptide mapping was performed, and protein aggregation was monitored by size exclusion chromatography (SEC). It could be demonstrated by ATR-FTIR that controlled precipitation did not harm the protein and the process is fully reversible. DSC measurements further confirmed these findings. No changes in the transition temperature and process were observed after precipitation and redissolution. Upon storage, isomerization and aggregation could be detected, but to a lower extent in the precipitated formulation as compared to a solution reference. Thus, controlled precipitation of rhBMP-2 is fully reversible and has the potential as alternative formulation tool for the generation of a microparticulate drug delivery system.

Bone Morphogenetic Protein 2↗

PubMed2004

Feasibility of preparing nanodrugs by high-gravity reactive precipitation.

To study the feasibility of producing nanoparticles of organic pharmaceuticals using a novel high-gravity reactive precipitation (HGRP) technique, reactive precipitation of benzoic acid as a model compound was carried out in a rotating packed bed under high gravity. The main factors such as the rotating bed speed, concentration and volume flow rate of the reactants (sodium benzoate and HCl) affecting the particle size of the precipitate were studied. Particle size was measured by transmission electron microscopy. Benzoic acid was precipitated as nanoparticles as fine as 10nm. The particle size was decreased with increasing rotating bed speed, concentration and volume flow rate of the reactants. The formation of ultrafine particles was due to intensified micro-mixing of reactants in the rotating bed to enhance nucleation while suppressing crystal growth. The results have demonstrated the feasibility to produce nanodrugs by the principle of acid-base precipitating reaction using HGRP.

Benzoic Acid↗

PubMed2005

An in vitro kinetic method for detection of precipitation of poorly soluble drugs.

A simple in vitro method for the detection of precipitation using 96-well microplates and a SpectraMax Plus microtiter plate reader has been developed and described. The method requires only small amount of drug and is, therefore, potentially applicable in early pre-formulation. The method is based on opacity changes that occur with precipitation and yields several descriptive parameters, onset time (Tonset), maximum rate (Vmax) and the time to reach Vmax (Tmax). Using these parameters, potential parenteral formulations can be ranked by their tendency to precipitate on dilution. We report use of this method and ranking of potential formulations of ricobendazole (RBZ), a poorly soluble anthelmintic, in various solvent systems. Detection at 500 nm was more sensitive than a wavelength of 550 nm and increased temperature (37 degrees C compared with 25 degrees C) accelerated precipitation. Results demonstrated the method was simple, descriptive and objective in the detection of precipitation of ricobendazole formulation on dilution and pH shift.

Albendazole↗

PubMed2006

Recovery of metals from Cuban nickel tailings by leaching with organic acids followed by precipitation and magnetic separation.

The percolation leaching of the Cuban nickel tailings containing 0.34% Ni, 0.08% Co and 44.2% Fe was investigated by using tartaric and oxalic acids at different concentrations. About 70% Ni, 80% Co and 30% Fe were extracted after 5 days of leaching with the mixture of 0.15 mol/L tartaric acid and 0.05 mol/L oxalic acid at ambient temperature and normal pressure. Nickel and cobalt extraction of 80% as well as iron extraction of 50% were achieved from the pregnant solution by means of precipitation at 80 degrees C for 2h. The precipitation at ambient temperature led to a similar result after 16 days. Cobalt, nickel and iron oxalates were found in the precipitate by using the X-ray diffraction method. The regeneration of acids during the precipitation step made possible the reuse of the raffinate at the leaching step. Heating of the precipitate at 200 degrees C increased the metal concentration to 1.22% Ni and 0.33% Co, which can be fed in the existing nickel plant in Moa, Cuba. The magnetic processing of the leaching residues led to a non-magnetic product containing less than 20% Fe and a magnetic product containing more than 50% Fe.

Carboxylic Acids↗

PubMed2006

On-line arsenic co-precipitation on ethyl vinyl acetate turning-packed mini-column followed by hydride generation-ICP OES determination.

An alternative and new system for on-line preconcentration of arsenic by sorption on a mini-column associated to hydride generation--inductively coupled plasma--optical emission spectrometry determination was studied. It is based on the sorption of arsenic on a column packed with ethyl vinyl acetate (EVA) turnings and the use of La(III) as co-precipitant reagent. This polymeric material was employed here for the first time as filling material for column preconcentration. It could work both as adsorbent and as sieve material. Sample and co-precipitant agent (lanthanum nitrate) were off-line mixed and merged with ammonium buffer solution (pH 10.0), which promoted precipitation and quantitative collection on the small EVA turnings. The arsenic preconcentrated by co-precipitation with lanthanum hydroxide precipitate was subsequently eluted with hydrochloric acid, which was the medium used for hydride generation. Considering a flow rate of 5 ml/min, three enrichment factors were obtained, 28-, 38- and 45-fold at three different sampling times, 60, 120 and 180s; respectively. The detection limits (3s) obtained for each case were 0.013, 0.009 and 0.007 microg/l. Additionally, the calculated precisions expressed as relatively standard deviation (R.S.D.) were 0.9, 1.3 and 1.1%. Satisfactory results were obtained for the determination of arsenic in standard reference material NIST 1643e Trace Elements in Water and drinking water samples.

Arsenic↗

PubMed2003

Fractionation of equine antivenom using caprylic acid precipitation in combination with cationic ion-exchange chromatography.

A combined process of caprylic acid (CA) precipitation and ion-exchange chromatography on SP-Sepharose was studied as a means to fractionate pepsin-digested horse antivenom F(ab')(2) antibody. In the CA precipitation, the optimal concentration for fractionation of F(ab')(2) from pepsin-digested horse plasma was 2%, in which 89.61% of F(ab')(2) antibody activity was recovered in the supernatant with 1.5-fold purification. A significant amount of pepsin was not precipitated and remained active under these conditions. An analytical cation exchanger Protein-Pak SP 8HR HPLC column was tested to establish optimal conditions for the effective separation of IgG, albumin, pepsin and CA from the F(ab')(2) product. From these results, the supernatant from CA precipitation of pepsin-digested plasma was subjected to a SP-Sepharose column chromatography using a linear salt gradient. With stepwise elution, a peak containing F(ab')(2) antibody could be obtained by elution with 0.25 M NaCl. The total recovery of antibody was 65.56% with 2.91-fold purification, which was higher than that achieved by ammonium sulfate precipitation. This process simultaneously and effectively removed residual pepsin, high molecular weight aggregates and CA in the final F(ab')(2) product, and should be suitable for large-scale fractionation of therapeutic equine antivenoms.

Animals↗

PubMed2004

Affinity precipitation of Aspergillus niger pectinase by microwave-treated alginate.

Affinity precipitation is a simple, single plate separation process in which the complex of a smart macroaffinity ligand with the target protein (from a crude broth) can be selectively precipitated by application of a suitable stimulus. Alginate is a copolymer of guluronic acid and mannuronic acid residues and precipitates with Ca(2+) ions. It was found to bind to pectinase present in a commercial preparation of Aspergillus niger, Pectinex Ultra-SPL. Microwave pretreatment of alginate at 75 degrees C was found to enhance the selectivity of the affinity precipitation. Using microwave-treated alginate, 83% of the enzyme activity with 20-fold purification could be recovered. SDS-PAGE upon silver staining confirmed the enhanced selectivity of affinity precipitation when microwave-treated alginate was used.

Alginates↗

PubMed2006

Vanadium recovery from oil fly ash by leaching, precipitation and solvent extraction processes.

In order to reduce the environmental impact due to land disposal of oil fly ash from power plants and to valorize this waste material, the removal of vanadium was investigated using leaching processes (acidic and alkaline treatments), followed by a second step of metal recovery from leachates involving either solvent extraction or selective precipitation. Despite a lower leaching efficiency (compared to sulfuric acid), sodium hydroxide was selected for vanadium leaching since it is more selective for vanadium (versus other transition metals). Precipitation was preferred to solvent extraction for the second step in the treatment since: (a) it is more selective; enabling complete recovery of vanadate from the leachate in the form of pure ammonium vanadate; and (b) stripping of the loaded organic phase (in the solvent extraction process) was not efficient. Precipitation was performed in a two-step procedure: (a) aluminum was first precipitated at pH 8; (b) then ammonium chloride was added at pH 5 to bring about vanadium precipitation.

Aluminum↗

PubMed2006

Effect of a magnetic water treatment on homogeneous and heterogeneous precipitation of calcium carbonate.

In this paper are reported experimental results on the effect of a magnetic field on the precipitation process of calcium carbonate scale from a hard water. Carbonically pure water was circulated at a constant flow rate in a magnetic field. After this treatment, calcium carbonate precipitation was induced by degassing dissolved carbonic gas. The nucleation time was identified from the variations of the pH and the Ca(2+) concentration. The ratio between homogeneous and heterogeneous nucleation was determined from the measurement of the mass of precipitated calcium carbonate. It is shown that the magnetic treatment increases the total amount of precipitate. This effect depends on the solution pH, the flow rate and the duration of the treatment. In addition, the magnetic treatment modifies the ratio between homogeneous/heterogeneous nucleation. Homogeneous nucleation is promoted by an increasing the pH of water, the flow rate as well as the residence time. The magnetic treatment enhances these effects with a maximum for a 15 min treatment time. It is shown that the presence of calcium carbonate colloid particles is not necessary. It is advanced that the main magnetic effects concern the associations of ionic species which are present in the solution and which are involved in the nucleation process of calcium carbonate precipitation.

Calcium Carbonate↗

PubMed1998

GlcNAc-terminated glycodendrimers form defined precipitates with the soluble dimeric receptor of rat natural killer cells, sNKR-P1A.

Synthetic GlcNAc-terminated thiourea-bridged glycoclusters were found to be potent inhibitors of binding of the soluble dimeric receptor of rat natural killer cells, sNKR-P1A protein, to its high affinity ligand. Moreover, we have shown here that characteristic precipitation curves can be recorded upon mixing of the GlcNAc glycoclusters with sNKR-P1A. For the GlcNAc8 glycocluster the precipitation curve is biphasic, with high affinity and low affinity precipitates differing in their sensitivity towards GlcNAc-mediated inhibition of precipitation. Quantitative analyses of the precipitates indicate the occurrence of a single sugar binding site per sNKR-P1A subunit, and lead to a model of the most possible spatial arrangements of the glycocluster-receptor lattices. These results provide new tools for further studies on carbohydrate recognition by NKR-P1A.

Acetylglucosamine↗

PubMed1995

Bilirubin inhibits calcium carbonate precipitation in gallbladder bile.

BACKGROUND: Previous studies have shown that human bile contains one or more factors that inhibit the precipitation of calcium carbonate from supersaturated solutions of calcium chloride and sodium bicarbonate. Lower concentrations of this factor have been observed in the gallbladder bile of patients with calcified gallstones. We hypothesized that gallbladder bile contains factors that inhibit calcium carbonate and these factors are present in varying concentrations in normal persons and in patients with cholesterol gallstones with and without calcium carbonate. METHODS: Gallbladder bile of patients without gallstones (n = 8) and of patients with cholesterol gallstones containing either calcium carbonate (n = 8) or other calcium salts (n = 8) was assayed for calcium carbonate inhibition. Individual components of bile (bilirubin, phospholipid, bile salts, and albumin) were tested in different concentrations in the same assay system. In addition, samples of model bile were tested. RESULTS: An inhibitory factor for calcium carbonate precipitation was present within all human gallbladder bile, irrespective of the absence, presence, or type of gallstones. The addition of a bilirubin-albumin solution to a supersaturated solution of calcium chloride and sodium bicarbonate entirely blocked precipitation of calcium carbonate from solution. In addition, serial dilutions of bilirubin exhibited a linear response between bilirubin concentration and inhibitory effect. Model bile and phospholipid dissolved in sodium taurocholate also exhibited a modest inhibitory effect on calcium carbonate precipitation. CONCLUSIONS: We conclude that bilirubin, cholesterol, and phospholipids incrementally interfere with calcium carbonate precipitation in supersaturated solutions through the preferential formation of a soluble calcium complex.

Bile↗