SEARCH · Search PubMed

Results for “PRECIPITATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,027 records · Page 57Linked to original sources

PubMed1998

Evaluation of in vitro precipitation methods.

Four in vitro precipitation methods were tested and evaluated using flavopiridol and diazepam formulations. The methods include static serial dilution, dynamic injection, and dropwise addition with and without stirring. The results generated from these methods are comparable and complementary. The static serial dilution method is most effective in quantifying the amount of precipitation and more descriptive of the formation and redissolution of the precipitate than the others. The dynamic injection method, however, has its merit in more realistically simulating the physiological environment of drug-blood interaction near the injection sites.

Antineoplastic Agents↗

PubMed1999

Encapsulation of lysozyme in a biodegradable polymer by precipitation with a vapor-over-liquid antisolvent.

Lysozyme was encapsulated in biodegradable polymer microspheres which were precipitated from an organic solution by spraying the solution into carbon dioxide. The polymer, either poly(l-lactide) (l-PLA) or poly(DL-lactide-co-glycolide) (PGLA), in dichloromethane solution with suspended lysozyme was sprayed into a CO2 vapor phase through a capillary nozzle to form droplets which solidified after falling into a CO2 liquid phase. By delaying precipitation in the vapor phase, the primary particles became sufficiently large, from 5 to 70 microm, such that they could encapsulate the lysozyme. At an optimal temperature of -20 degrees C, the polymer solution mixed rapidly with CO2, and the precipitated primary particles were sufficiently hard such that agglomeration was markedly reduced compared with higher temperatures. More uniform particles were formed by flowing CO2 at high velocity in a coaxial nozzle to mix the droplets at the CO2 vapor-liquid interface. This process offers a means to produce encapsulated proteins in poly(DL-lactide-co-glycolide) microspheres without earlier limitations of massive polymer agglomeration and limited protein solubility in organic solvents.

Animals↗

PubMed2001

Uranyl precipitation by biomass from an enhanced biological phosphorus removal reactor.

Heavy metal and radionuclide contamination presents a significant environmental problem worldwide. Precipitation of heavy metals on membranes of cells that secrete phosphate has been shown to be an effective method of reducing the volume of these wastes, thus reducing the cost of disposal. A consortium of organisms, some of which secrete large quantities of phosphate, was enriched in a laboratory-scale sequencing batch reactor performing Enhanced Biological Phosphorus Removal, a treatment process widely used for removing phosphorus. Organisms collected after the aerobic phase of this process secreted phosphate and precipitated greater than 98% of the uranyl from a 1.5 mM uranyl nitrate solution when supplemented with an organic acid as a carbon source under anaerobic conditions. Transmission electron microscopy, energy dispersive x-ray spectroscopy, and fluorescence spectroscopy were used to identify the precipitate as membrane-associated uranyl phosphate, UO2HPO4.

Biomass↗

PubMed2003

Metal chelate affinity precipitation of RNA and purification of plasmid DNA.

The affinity of metal chelates for amino acids, such as histidine, is widely used in purifying proteins, most notably through six-histidine 'tails'. We have found that metal affinity interactions can also be applied to separation of single-stranded nucleic acids through interactions involving exposed purines. Here we describe a metal affinity precipitation method to resolve RNA from linear and plasmid DNA. A copper-charged copolymer of N-isopropyl acrylamide (NIPAM) and vinyl imidazole (VI) is used to purify plasmid from an alkaline lysate of E. coli. The NIPAM units confer reversible solubility on the copolymer while the imidazole chelates metal ions in a manner accessible to interaction with soluble ligands. RNA was separated from the plasmid by precipitation along with the polymer in the presence of 800 mM NaCl. Bound RNA could be recovered by elution with imidazole and separated from copolymer by a second precipitation step. RNA binding showed a strong dependence on temperature and on the type of buffer used.

Acrylamides↗

PubMed2004

Enhanced wet deposition estimates using modeled precipitation inputs.

Effective assessments of linkages between atmospheric deposition and sensitive aquatic and terrestrial ecosystems require a knowledge of spatial patterns in deposition of greater resolution than currently available using point estimates and two-dimensional surface algorithms. A high resolution wet deposition model was developed for the Eastern U.S.A. by incorporating daily precipitation measurements from National Oceanic and Atmospheric Administration (NOAA) monitoring sites located within the Eastern U.S.A.; topographic variables, including elevation, slope, and aspect that affect the amount and distribution of precipitation across the region; and precipitation chemistry data from National Atmospheric Deposition Program (NADP) sites within and adjacent to the region. Model performance, which was tested against independent measurements from three physiographic regions of the eastern U.S.A., revealed a statistically significant reduction in interpolation error compared to traditional two-dimensional surface algorithms.

Air Pollutants↗

PubMed2006

Changes in precipitation chemistry in Lithuania for 1981-2004.

This paper considers the spatial and temporal variability in concentrations of the potentially acidifying ions in precipitation in Lithuania during the 1981-2004 period. Chemical analysis of precipitation included measurements of pH, conductivity, sulfate (SO4(2-)), nitrate (NO3-), chloride (Cl-), ammonium (NH4+), sodium (Na+), potassium (K+), and calcium (Ca2+). Temporal trends in the potentially acidifying ion concentrations in precipitation and wet deposition were evaluated using the non-parametric Mann-Kendall test and Sen's slope estimator. A statistically significant decline was observed in non-sea salt sulfate (nssSO4(2-)) and hydrogen (H+) ions concentrations (82% and 79%, respectively) and wet depositions (88% and 74%, respectively). Temporal trends both in concentration and wet deposition of nitrate and ammonium were not as pronounced as trends in sulfate concentration. Analysis of air mass backward trajectories was applied to reveal the influence of air mass originating in different regions on wet deposition of acidifying species in Lithuania. Sector analysis clearly showed that wet deposition of sulfur and nitrogen in Lithuania is to a large extent anthropogenic and the main source regions of acidifying species contributing to wet deposition in Lithuania are in South and Central Europe.

Acid Rain↗

PubMed2004

Separation of immunoglobulin G precipitate from contaminating proteins using microfiltration.

A small-scale stirred-cell device was used to separate an antivenom antibody precipitate from a suspension containing contaminating soluble proteins. The device has a total volume of 200 ml and is equipped with a filter membrane with a cut-off size of 3 microm. About 90% of the antibody-precipitate particles in the feed were 29 microm or smaller, and the concentration of solids was 12% (w/w). The microfiltration cell was operated in a constant-volume (continuous/diafiltration) mode, and its performance was compared with an industrial disc-stack centrifuge currently used in the manufacture of antibody precipitate. In terms of product purity, the separation performance of the microfiltration operation was found to be comparable with the disc-stack centrifuge, whereas the overall yield was 10% better than that obtained from the centrifuge. This was attributed to the ability of microfiltration to reduce material losses by integrating a number of operations in a single piece of equipment. These included separation, concentration and buffer exchange, as well as dissolution and final recovery of the antibody in an appropriate buffer. The results obtained from the stirred cell are potentially scaleable, and dynamic microfiltration is shown to be an attractive process option.

Blood Proteins↗

PubMed1971

Selective precipitation of ribonucleic acid from a mixture of total cellular nucleic acids extracted from cultured mammalian cells.

A simple and reproducible method is described for precipitating RNA selectively from total mammalian-cell nucleic acids extracted by the phenol-sodium dodecyl sulphate procedure at pH8.0. Under specified conditions bulk RNA is precipitated almost quantitatively whereas bulk DNA remains in solution. Minor components of RNA (detected by pulse-labelling and chromatography on methylated albumin-kieselguhr) and rapidly labelled components of DNA containing single-stranded regions are also precipitated. The usefulness of the method is discussed in the context of isolating separately both RNA and DNA from cultured cells that are difficult to obtain in quantity.

Animals↗

PubMed1987

Improvement on the competitive binding assay for the measurement of cyclic AMP by using ammonium sulphate precipitation.

The protein-binding assay developed by Brown, Albano, Ekins, Sgherzi & Tampion [(1971) Biochem. J. 121, 561-562] and Brown, Ekins & Albano [(1972) Adv. Cyclic Nucleotide Res. 2, 25-40] was modified by using precipitation with (NH4)2SO4 of the protein-cyclic AMP complex instead of adsorption of the free nucleotide on charcoal. The half-life of the protein-cyclic AMP complex obtained in the presence of charcoal was lower than that of the (NH4)2SO4-precipitated complex. In consequence, owing to the great stability of the precipitated protein-cyclic AMP complex, this method allows more accurate and reproducible determinations.

Ammonium Sulfate↗

PubMed2001

Identification of the precipitate in alkalinized solutions of mepivacaine and bupivacaine at 37 degrees C.

Commercial and control solutions of bupivacaine (0(.)75%) and mepivacaine (1(.)5%) were alkalinized with bicarbonate until cloudy at room temperature. The solutions were heated to 37 degrees C for 2(.)5 h. The precipitates were filtered, lyophylized and analysed by fast atom bombardment mass spectrometry. Analysis showed the precipitates to be predominantly the free base of the local anaesthetic. The precipitate of the commercial bupivacaine solution also contained a small amount of the hydrochloride salt. The mepivacaine control crystals contained an unknown at molecular weight 528, which may represent a dimer of the free base and hydrochloride salt.

Anesthetics, Local↗

PubMed2001

Inhibition of calcium oxalate precipitation by bile salts.

BACKGROUND: Both urinary and biliary stones can contain calcium. Bile salts (BA), which are known to bind Ca2+, are commonly used to dissolve the latter but not the former. METHODS: The effect of physiologic BA on calcium oxalate (CaOx) precipitation was evaluated by a recently developed method. RESULTS: The Ca2+ binding properties of BA were confirmed by small but significant decreases in pH observed following addition of CaCl2 to bile acids solutions. More importantly, BA inhibited CaOx precipitation with effective concentrations of approximately 10-3 mol/L. The clinical relevance of the latter observation is presently unknown but it is of note that in the same in vitro assay, the activity of BA appeared comparable to that of citric acid, the most common drug for urolithiasis. Although BA do not reach mmol/L levels in urine, they are known to change the physicochemical properties of this fluid, possibly slowing down the crystal growth process. However, the hypothetical therapeutic use of BA in former stone patients would present at least two major problems: (i) hepatotoxicity and (ii) lithogenic activity, due to hyperoxaluria subsequent to increased intestinal absorption of oxalate. CONCLUSION: The ability of BA in effectively binding calcium ions and in inhibiting the precipitation of CaOx appears of interest from both a physiopathologic and a pharmacologic point of view, even if it does not currently seem exploitable for prophylactic or therapeutic purposes.

Bile Acids and Salts↗

PubMed2003

Cell density related H2 consumption in relation to anoxic Fe(0) corrosion and precipitation of corrosion products by Shewanella oneidensis MR-1.

In the absence of oxygen, a protective H2 film is formed around an Fe(0) surface, inhibiting the electron flow from this surface. Our study of anoxic corrosion of Fe(0) beads revealed that, in the presence of Shewanella oneidensis MR-1, H2 removal and precipitation of Fe mineral particles on the cell surface are determining processes for corrosion. These two biologically mediated processes were governed by cell density. H2 removal by Shewanella oneidensis was detected at cell concentrations of 1.0 x 10(6) live cells ml-1 and higher and H2 was electron donor for denitrification of NO3-. The removal of the protective H2 layer from Fe(0) beads by Shewanella oneidensis, resulted in an increase of Fe release out of the Fe(0) beads from 153 +/- 25 mg l(-1) to 196 +/- 7 mg l-1 after 20 h. When the cell concentration exceeded 1.0 x 10(8) live cells ml-1, precipitation of iron minerals on the cell surface was characteristic for the greatest percentage of MR-1 cells, whereas micrometre-scale iron precipitates not associated with culturable cell biomass significantly decreased in number. Addition of supernatant of a corrosion assay with high cell concentration induced metabolic activity in a corrosion assay with low cell concentration, resulting in increased H2 consumption and Fe release from Fe(0) beads. Homoserine lactone-like molecules were detected in the supernatant by a bio-assay, suggesting the involvement of a quorum-sensing regulatory mechanism.

4-Butyrolactone↗

PubMedDate not supplied

The occurrence of precipitating antibodies in transfused Japanese patients with hereditary ninth component of complement deficiency and frequency of C9 deficiency.

Antibodies to the ninth component of complement (C9) were found in a patient with hereditary C9 deficiency (C9D) who had received multiple transfusions. The incidence of anti-C9 precipitating antibodies following transfusion was investigated in 63,625 patients treated at Kyushu University Hospital, and 475,886 blood donors at the Fukuoka Red Cross Blood Center were studied to determine the frequency of C9D in Japan. Transfusion reactions in recipients having anti-C9 were also monitored. One hundred and eighty-six subjects (15 patients and 171 donors) with C9D were identified (a prevalence of 0.036%). Four of 15 C9-deficient patients had received transfusions. One of the patients who had received several units of blood within 1 week developed low-titer C9-precipitating antibody. This patient was transfused in the presence of the antibody without evidence of adverse reactions. No precipitating antibody was detected in the remaining three patients who had received several units of blood on a single day. These observations suggest that multiple transfusions may contribute to the development of anti-C9.

Chemical Precipitation↗

PubMed1974

Abnormal precipitation of oxyhemoglobin S by mechanical shaking.

The oxy-form of sickle hemoglobin (Hb S) is abnormally unstable and precipitates at a 10-fold faster rate than does oxyhemoglobin A (oxy-Hb A) during mechanical shaking. The apparent rate of precipitation of heterozygous hemolysate (AS) is approximately half that of oxy-Hb S. The deoxy-form of Hb S, on the other hand, is resistant to the mechanical treatment. This stabilization is attributed to the conformational change of hemoglobin rather than the lack of oxygen, because carbonmonoxide hemoglobin S, which is known to have conformational properties similar to those of oxy-Hb, is unstable even under anaerobic conditions. Methemoglobin S is most unstable, although addition of cyanide stabilizes the protein. The precipitation of oxy-Hb S is inhibited by ethanol and other organic solvents. The relationship of the mechanical instability of sickle oxyhemoglobin to intraerythrocytic denaturation and vaso-occlusive phenomena in sickle cell disease to be determined.

Buffers↗

PubMed1982

Optimization of the ethanol precipitation of RNA from formamide containing solutions.

This study shows that high variability and low recoveries are obtained when conventional ethanol precipitation is used to recover RNA from the 70%-90% formamide containing solutions that are used to elute poly(U) Sepharose columns. Precipitations of RNA at different formamide concentrations show that the variability of the recovery increases with increasing formamide concentration and the recovery decreases by 7% for each 10% increase in the formamide concentration. The formamide concentration curve shows that these factors can be optimized by diluting the formamide containing solutions at least to 30% formamide prior to the precipitation.

Chemical Precipitation↗

PubMed2004

Precipitation of heavy metals from landfill leachates by microbially-produced sulphide.

Four leachates from two landfills in Sweden were treated for the removal of heavy metals with the aid of sulphate-reducing bacteria (SRB). Both continuous and batch experiments were performed. A packed-bed process was used for sulphide production. The metals studied were As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn. The continuous experiments showed that Cd and Cu were most efficiently removed and that Cr was the most difficult to precipitate. In a continuous experiment with one of the leachates, the removal of Cd, Cu and Zn depended upon the retention time in the system. In the batch experiments, precipitation of the metals was a relatively fast process. No significant differences in metal concentrations were found between experiments terminated after a day and those terminated after a week. In a batch experiment involving one of the leachates, the precipitation of Cd and Cu was shown to be dependent upon the metal:sulphide ratio. Removal of the metals increased with an increase in the sulphide:metal ratio up to 45:1. The process with SRB showed an interesting potential for removal of heavy metals from leachates. One of the two leachates for which the highest metal removals were obtained came from a landfill for hazardous waste.

Bioreactors↗

PubMed2006

An exemple of particle concentration reduction in Parisian subway stations by electrostatic precipitation.

The air quality in Parisian subway stations is a great concern to users and the public authorities. Particle concentration is one of the major problems; indeed concentrations observed in stations are generally superior to those collected in the street. The subway generates its own particles from wheels / rail contact, braking, the ground... One of the ways explored to lower this level of particles is a removal treatment: the principle is to treat the ambient air using a suitable system placed in stations. Following literature, the process chosen by Paris Transport Authority is the electrostatic precipitator. An electrostatic precipitator prototype from the Recycl'Air company is installed in May 2001 in a closed station on the 5th line (Italy Place -Bobigny). Results show that, by the end of approximately one year, the efficiency has fallen by 15% and it is therefore necessary to clean the precipitation cartridges. A consideration has also been made on the possibility to equip an entire subway station. According to the results obtained, about twenty filters placed in the top of a non mechanically ventilated station would permit to half an initial concentration in particles of 230 microg m(-3).

Air Pollution↗

PubMed2000

Precipitate production by some Malassezia species on Dixon's agar.

The production of a precipitate by Malassezia species on Dixon's agar was observed. Malassezia furfur (n = 12), M. obtusa (n = 2) and M. slooffiae (n = 3) were precipitate negative, while M. sympodialis (n = 32) and M. globosa (n = 6) were precipitate positive. This test may be useful in differentiating Malassezia species.

Agar↗