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PubMed1983

31P NMR as a spectroscopic monitor of the spontaneous precipitation of calcium phosphates.

High-resolution 31P NMR spectroscopy is shown to be a potentially valuable new method for monitoring the spontaneous precipitation of calcium phosphates from metastable supersaturated solutions. An apparatus capable of pH-statting the sample in a spinning 20 mm NMR sample tube is briefly described. The spontaneous precipitation of dicalcium phosphate dihydrate, CaHPO4 X 2H2O, pH-statted at pH 5, is characterized by a base-uptake curve which follows the decrease in the intensity of the solution 31P resonance. The precipitation of amorphous calcium phosphate at neutral pH, which exhibited an induction period of approximately 10 min, was also studied. No evidence of NMR peaks from transient clusters or the initial colloidal solid phase has been seen.

Calcium Phosphates↗
PubMed1985

The precipitation of calcium carbonate polymorphs in vitro at 37 degrees C.

In order to determine some of the factors that affect the formation of the three polymorphs of calcium carbonate in gallstones, its precipitation from undisturbed solutions containing calcium chloride and sodium bicarbonate was studied. The variation in the amount of calcium carbonate formed with time was studied by weighing the precipitate, and the percentages of calcite, vaterite, and aragonite were determined by x-ray diffraction (XRD) analysis. The effects of additives and stirring were noted. Minor changes in conditions were sufficient to affect the formation of the polymorphs, and all three polymorphs could be found simultaneously in some solutions. It is suggested that no great differences in precipitating conditions need to be postulated to account for the presence of different polymorphs in gallstones. Aragonite seems to be formed slowly in undisturbed conditions.

Bicarbonates↗
PubMed1987

Inhibition of calcium phosphate precipitation by human salivary acidic proline-rich proteins: structure-activity relationships.

Absence of precipitation of calcium phosphate salts onto tooth surfaces from human saliva, which is supersaturated with respect to calcium phosphate salts, has been attributed in part to the presence in the salivary secretions of a group of acidic proline-rich phosphoproteins (PRP). These macromolecules are considered to act by adsorbing onto dental enamel where they inhibit surface-induced precipitation of calcium phosphate salts. The inhibitory activity is known to be associated primarily with the amino-terminal region of the PRP. The aim of this study was to determine the features of the primary structure of this molecular segment responsible for inhibitory activity. The 30-residue, amino-terminal segment of PRP-3, which contains the two phosphoserines and 11 of the 13 carboxyl groups present in PRP-3, was obtained by tryptic digestion. This peptide, designated PRP-3(TI), was treated with thermolysin to give the monophosphopeptides, Val-PSer-Gln-Glu-Asp-Val-Pro and Leu-Val-Ile-Ser-Asp-Gly-Gly-Asp-PSer-Glu-Gln, and with alkaline phosphatase to give the dephosphorylated analog, PRP-3(TI)DP. The inhibitory activities of PRP-3(TI) and the derived peptides, a synthetic peptide, phosphoseryl-phosphoserine (PSer-PSer), and O-phosphoserine (PSer), were determined using an assay based on inhibition of seeded precipitation of calcium phosphate. Inhibitory activities, expressed as concentrations of inhibitors required to give standard inhibitory activities, were PRP-3(TI), 0.59 microM; PSer-PSer, 3.5 microM; the two monophosphopeptides, 29 and 32.5 microM; PRP-3(TI)DP, 56 microM; PSer, 329 microM.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium Phosphates↗
PubMed2004

Water-dispersed bone morphogenetic protein nanospheres prepared by co-precipitation method.

A modified complex coacervation-co-precipitation method was used to prepare bone morphogenetic protein (BMP)-loaded nanospheres. Three natural polymers were used as packing materials to obtain nanoscale delivery device for BMP, in the presence of phosphatidylcholine functioning as stabilizer. Positively charged polysaccharide, N,N-diethylaminoethyl dextran (DEAE-dextran) tended to form stable, uniform and smaller size particles carrying BMP. Negatively charged bovine serum albumin (BSA) induced precipitation of the produced BMP particles due to its weak interaction with BMP molecules, although it produced nanosized BMP spheres. While collagen, a weakly positively charged protein shaped larger particles due to the strong interaction among themselves. A mechanism of co-precipitation process was also deduced to depict the formation of stable nanospheres.

Animals↗
PubMed1999

Ammonium and sodium urates precipitating from synthetic urine and fine structure of urate renal calculi.

A study of ammonium and sodium urate precipitation in vitro and the fine structure of several urate renal calculi was carried out to contribute to an understanding of the participation of ammonium and sodium urates in urolithiasis. Ammonium urate precipitated in vitro in two different morphologies: a typical spherulite morphology formed at high supersaturation and disorganized needle-like crystals formed at low supersaturation. In all cases sodium urate precipitated in vitro as bundles of curved fibrils, its crystallization being inhibited by calcium in concentrations between 20 and 60 mg/l depending on the sodium urate supersaturation. From a collection of 1300 renal calculi, only three had ammonium urate as their main component (0.2%), three were mixed calculi (0.2%) consisting of ammonium urate and calcium oxalate (two) or uric acid (one), and in one calculus ammonium urate was present as a minor component. Only in a mixed calculus of uric acid and calcium oxalate was sodium urate detected in a very low quantity. The study of the fine structure of the renal calculi constituted mainly by ammonium urate demonstrated similar patterns in which spherulites, needle-like individual crystals and an amorphous mass of ammonium urate with abundant organic matter in non-organized structures coexist. As minor components, struvite or calcium oxalate crystals were found. A general mechanism of the formation of such calculi is proposed.

Chemical Precipitation↗
PubMed2006

Precipitate inside the epithelial iris cyst: a report of two cases.

BACKGROUND: Epithelial iris cyst is a rare disease with various complications. To our knowledge, precipitate formation inside the cyst has never previously been described. The purpose of this report is to introduce this extremely atypical complication of epithelial iris cyst. METHODS: This case report presents two men out of 142 cases, aged 30 and 36, with epithelial iris cyst who developed precipitate level inside the lesions. The cyst fluid was drained and sent to the laboratory. Intracystic ethanol irrigation was performed as a treatment procedure. The patients were followed for 2 and 8 years. RESULTS: There was no inflammatory response outside the cysts. Both cysts contained lymphocytes and one included epithelial cells, but neither contained organisms. The cysts were treated successfully by intracystic ethanol irrigation. CONCLUSIONS: Intracystic precipitate formation is a rare manifestation of the epithelial iris cyst.

Adult↗
PubMed2006

Precipitation chemistry and occurrence of acid rain over Dhanbad, coal city of India.

The present study investigated the chemical composition of wet atmospheric precipitation over Dhanbad, coal city of India. The precipitation samples were collected on event basis for three years (July 2003 to October 2005) at Central Mining Research Institute. The precipitation samples were analyzed for pH, conductivity, major anions (F, Cl, NO(3), SO(4)) and cations (Ca, Mg, Na, K, NH(4)). The pH value varied from 4.01 to 6.92 (avg. 5.37) indicating acidic to alkaline nature of rainwater. The pH of the rainwater was found well above the reference pH (5.6), showing alkalinity during the non-monsoon and early phase of monsoon, but during the late phase of monsoon, pH tendency was towards acidity (<5.6 pH) indicating the non-availability of proper neutralizer for acidic ions. The observed acidic events at this site were 91, (n = 162) accounting 56% for the entire monitoring months. The (NO(3) + Cl)/SO(4) ratio in majority of samples was found below 1.0, indicating that the acidity is greatly influenced by SO(4). The calculated ratio of (Ca + NH(4))/(NO(3) + SO(4)) ranges between 0.42-5.13 (average 1.14), however in most of the samples, the ratio is greater than unity (>1.0) indicating that Ca and NH(4) play an important role in neutralization of acidic ions in rainwater. Ca and SO(4) dominate the bulk ionic deposition and these two ions along with NH(4) accounts 63% of the annual ionic deposition.

Acid Rain↗
PubMed2005

Characterization of condensed tannins purified from legume forages: chromophore production, protein precipitation, and inhibitory effects on cellulose digestion.

To identify simple screening tools for selecting condensed tannin (CT)-containing forages as candidate sources for further study, CT were isolated from nine legumes, and their molecular weights (MW), chromophore production, capacity to precipitate bovine serum albumin (BSA) and Fraction 1 protein (Rubisco) isolated from alfalfa, and inhibition of filter paper digestion were compared. Sources were as follows: leaves of sericea lespedeza (Lespedeza cuneata Dum.-Cours.), crown vetch (Coronilla varia L.), and sainfoin (Onobrychis viciifolia Scop.); stems of hedysarum (Hedysarum alpinum L.); seeds of alfalfa (Medicago sativa L.); and whole plants of birdsfoot trefoil (Lotus corniculatus var. corniculatus L.) and three varieties of big trefoil (Lotus pedunculatus Cav.), viz., Lotus uliginosus Schkuhr, L. uliginosus var. glabriusculus, and L. uliginosus var. villosus. Molecular weights and sizes (degrees of polymerization) of the CT varied considerably within and among plant species. Average MW ranged from 3036 Da (crown vetch) to 7143 Da (lespedeza). All CT exhibited greater capacity (w/w basis) to bind alfalfa Rubisco than BSA. Relative astringencies (microg CT required to precipitate 1 mg protein) against BSA ranged from 262.5 for CT from lespedeza to 435.5 for CT from L. corniculatus, and against Rubisco, from 49.6 (sainfoin) to 108.2 (alfalfa seed). Including CT at 300 microg/ml in cultures of Fibrobacter succinogenes reduced digestion of cellulose filter paper by 19.8% (sainfoin) to 92.4% (crown vetch) and increased the specific activity of cell-associated endoglucanase. There were no correlations between inhibitory effects of CT on filter paper digestion and (1) chromophore formation during CT assay by butanol-HCl, vanillin-HCl, or H2SO4; (2) precipitation of BSA or alfalfa Rubisco; and (3) MW of CT. The most inhibitory CT for cellulose digestion included those with broad and with narrow MW distributions. Sainfoin was the most desirable source of CT, as it had the highest capacity to bind alfalfa protein and was least inhibitory to cellulose digestion by F. succinogenes. This study suggests that these properties are not easily defined via chemical means, and that biological assays using rumen bacteria may help identify those CT with properties of nutritional interest.

1-Butanol↗
PubMed2006

A modified method for determining tannin-protein precipitation capacity using accelerated solvent extraction (ASE) and microplate gel filtration.

The protein precipitation assay used by Robbins et al., (1987) Ecology 68:98-107 has been shown to predict successfully the reduction in protein availability to some ruminants due to tannins. The procedure, however, is expensive and laborious, which limits its utility, especially for quantitative ecological or nutritional applications where large numbers of assays may be required. We have modified the method to decrease its cost and increase laboratory efficiency by: (1) automating the extraction by using Accelerated Solvent Extraction (ASE); and (2) by scaling and automating the precipitation reaction, chromatography, and spectrometry with microplate gel filtration and an automated UV-VIS microplate spectrometer. ASE extraction is shown to be as effective at extracting tannins as the hot methanol technique. Additionally, the microplate assay is sensitive and precise. We show that the results from the new technique correspond in a nearly 1:1 relationship to the results of the previous technique. Hence, this method could reliably replace the older method with no loss in relevance to herbivore protein digestion. Moreover, the ASE extraction technique should be applicable to other tannin-protein precipitation assays and possibly other phenolic assays.

Chemical Precipitation↗
PubMed1984

Colorimetric determination of microgram quantities of polylysine by trypan blue precipitation.

A simple and sensitive method for the determination of polylysine in solution is described. Polylysine is quantitatively precipitated with trypan blue. The absorbance of unbound dye in the supernatant is inversely proportional to the concentration of this polyamino acid. The precipitation is identical for all sizes of polylysine of molecular weight 13,000 or higher, and is prevented by the addition of either polyanions or serum. The measurable range of polylysine hydrobromide is between 1 and 10 micrograms/ml, which is about 10-fold lower than that by the published methyl orange precipitation method.

Azo Compounds↗
PubMed1984

Protamine sulfate precipitation: a new assay for the Ah receptor.

The ability of protamine sulfate to effect the quantitative precipitation of 2,3,7,8-[3H]tetrachlorodibenzo-p-dioxin (TCDD):Ah receptor complexes from rat liver cytosol has been developed into a new assay for the identification, quantitation, and characterization of the Ah receptor. The method is reliable, uncomplicated, and rapid, and can be applied to large numbers of samples. The major advantage of the assay is that protamine sulfate appears to selectively precipitate the Ah receptor protein and does not precipitate a number of other proteins that bind [3H]TCDD nonspecifically.

Animals↗
PubMed1985

Precipitation of phenyl and phenoxypenicillin from solutions using ammonium sulfate.

An easy, rapid, and available method for separating 6-aminopenicillanic acid (6-APA), benzylpenicillin (penicillin G), and other related molecules from aqueous solutions or complex industrial broths is described. A high concentration of ammonium sulphate induces partially or totally the precipitation of the penicillin present in the solutions, while 6-APA, phenylacetic, and phenoxyacetic acid always remain in the supernatant. The filtration through No. 4 Pyrex glass-fiber filter or Whatman 3MM paper permits the separation of the compounds present in the supernatant from the other ones precipitated. The precipitated product was identified, in all cases, as ammonium penicillin. This method is described here for the first time.

Ammonium Sulfate↗
PubMed1986

Lead precipitation: an aid to separation of dermatan and mucokeratan sulfates from glycosaminoglycan mixtures.

Dermatan sulfate with a high iduronate content may be precipitated selectively from solution with lead acetate at neutral pH. Other glycosaminoglycans, including dermatan sulfate with appreciable glucuronate content, are in general not precipitated. Both dermatan sulfate and mucokeratan sulfate are precipitable by the alkaline copper procedure, so that prior removal by lead acetate of some or all of the dermatan sulfate from a mixture of glycosaminoglycans permits concentration of mucokeratan sulfate. This eases considerably the detection and isolation of this recently identified glycosaminoglycan.

Animals↗
PubMed1991

Selective precipitation of proteins from guanidine hydrochloride-containing solutions with ethanol.

The solubility of guanidine hydrochloride in ethanol and conversely the low solubility of proteins have been used as the basis for a procedure for recovering proteins from guanidine-containing solutions by selective precipitation. Yields of greater than 94% were observed with as little as 28 ng protein and of 98% for larger quantities of protein up to 20 mg/ml. The precipitations were independent of molecular weight for proteins in the range of 6-100 kDa and could be run in as little as 5 min at room temperature. Unlike the conventional desalting methods for removing guanidine, ethanol precipitation is rapid, efficient, and can be applied simultaneously to a large number of samples. The approach should have a wide range of applications.

Bacterial Proteins↗
PubMed1992

Efficient precipitation and accurate quantitation of detergent-solubilized membrane proteins.

The protein assay method of I. Polacheck and E. Cabib (Anal. Biochem. 117, 311-314, 1981) has been modified to provide a general method for quantitating protein samples in the presence of detergents. Dilute detergent-solubilized membrane proteins, by using ribonucleic acid as a carrier, have been efficiently precipitated here by trichloroacetic acid (TCA) in the presence of sodium dodecyl sulfate (SDS). Washing the pellets once with TCA solution has removed most of the reagents present in the original sample. The washed sample could then be quantitated by the Lowry method (O. J. Lowry, N. J. Rosebrough, A. L. Farr, and R. J. Randall, J. Biol. Chem. 193, 265-275, 1951). This procedure could be used to assay protein solutions of a concentration as low as 5 micrograms/ml in the presence of the following reagents: Triton X-100, Triton X-114, Tween 20, N-octylglucoside, deoxycholate, cholate, Thesit, octanoyl-N-methylglucamide, isotridecylpoly (ethyleneglycoether)n, Nonidet P-40, glucose, methyl-D-glucopyranoside, methyl-D-mannopyranoside, N-acetyl-glucosamine, Mn2+, Ca2+, Mg2+, and many buffer reagents. Proteins solubilized from porcine brain myelin sheath and synaptic plasma membranes were quantitated by amino acid analysis and by the TCA/SDS precipitation method described here. The resultant protein concentrations were almost identical. The results have suggested this TCA/SDS precipitation method to be useful for quantitating dilute protein samples containing high concentrations of detergents and other reagents commonly employed in studying membrane proteins.

Animals↗
PubMed1987

The effect of Gla-containing proteins on the precipitation of insoluble salts.

The precipitation of insoluble salts containing divalent metal ions is inhibited by Gla-containing proteins of various origin. In this paper we demonstrate that: Gla-residues are required for the inhibitory activity; the inhibition is effected by a protein which in vivo is bound to calcified tissue (osteocalcin) as well as by proteins occurring in blood plasma (factor X) and urine (the urinary Gla-protein); The inhibitor concentration required for 50% precipitation-inhibition varied slightly from one salt to the other, but no marked differences were observed between the effects of the various Gla-containing proteins used; Precipitation-inhibition occurred in all phosphates (Be, Ca, Mn and Zn) and in all calcium salts (phosphate, oxalate and carbonate) tested.

1-Carboxyglutamic Acid↗
PubMed1991

Precipitation and 13C-NMR relaxation enhancement measurements of the interactions of bile acids with synthetic cationic bile acid derivatives, and with spin labelled fatty acids.

In an investigation of novel potential bile acid sequestrants, the affinities of the sodium salts of the glycine and taurine conjugates of naturally occurring bile acids (cholate, deoxycholate, chenodeoxycholate and lithocholate) for several cationic ammonium bile acid derivatives have been investigated by measurements of the extent to which the derivatives are able to precipitate the bile acids. This is roughly proportional to the lipophilicity of the interacting species. Thus, amino and ammonium derivatives of cholic acid do not precipitate taurocholate or glycocholate to any great extent, whereas ammonium derivatives of deoxycholate and lithocholate are much more effective. To complement the precipitation measurements, high resolution 13C-NMR has been applied to investigate the weaker interactions between the ammonium cholate derivative and glycocholate, glycodeoxycholate and glycochenodeoxycholate. Addition of either of the latter two bile acids to the cationic ammonium compound results in considerable broadening of the 13C resonances of both species, indicating the formation of relatively rigid structures. In addition, we have used T2 relaxation enhancement induced by spin-labelled fatty acids to examine the mechanism of interaction with bile acids of amphiphilic anions, which might compete with bile acids for sites on bile acid sequestrants. Low concentrations of 16-DOXY L-Stearate dramatically broaden the 13C-NMR resonances of deoxycholate carbons 19, 18 and 7 in particular, while 5-DOXY L-Stearate exerts much less specific effects. These results have been incorporated into a snapshot model of bile acid-fatty acid interactions.

Bile Acids and Salts↗
PubMed1994

Heparin extracorporeal LDL precipitation (HELP): an effective apheresis procedure for lowering Lp(a) levels.

Heparin-induced extracorporeal low-density lipoprotein precipitation (HELP) is based on the precipitation of apolipoprotein B (apo B) containing lipoproteins with heparin at low pH (4.85). In in vitro experiments we could show that Lp(a) is quantitatively (> 99%) precipitated from plasma by heparin in the pH range 4.6-5.2. The acute changes in Lp(a) after a single HELP-LDL apheresis were investigated in twelve patients with Lp(a) concentrations > 30 mg/dl. A single treatment caused a highly significant decrease (62%) in the concentration of Lp(a), similar to the decrease (60%) observed for LDL-cholesterol. Analysis of the data from ten patients with different apo(a) phenotypes indicated that Lp(a) is eliminated with almost 100% efficiency in the extracorporeal circulation, irrespective of apo(a) phenotype and plasma concentration. The mean rate of recovery of Lp(a) following HELP-LDL apheresis was slightly slower than that of LDL-cholesterol. Plasma Lp(a) concentrations were monitored in seven patients over 2 years. Mean Lp(a) concentrations after 2 years were lower than pre-treatment levels, indicating that repeated elimination of the lipoprotein does not lead to an induction in its synthesis. HELP-LDL apheresis should be particularly suitable for treatment of patients with elevated LDL-cholesterol levels who are also at increased coronary risk because of high Lp(a) concentrations.

Apolipoproteins↗