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PubMed2001

Detection of macroprolactinemia with the polyethylene glycol precipitation test in systemic lupus erythematosus patients with hyperprolactinemia.

The objective of this study was to determine the diagnostic performance of the percentage of serum prolactin (PRL) precipitated with polyethylene glycol (PEG) for the detection of macroprolactinemia in systemic lupus erythematosus (SLE) patients with hyperprolactinemia. Serum samples from SLE patients were examined. Serum PRL was measured by immunoradiometric assay (IRMA) and samples with hyperprolactinemia (> 20 ng/ml) were submitted to PEG precipitation, gel filtration chromatography and affinity chromatography with protein-G sepharose. A comparative survey was used. Among 259 consecutive serum samples from SLE patients, PRL was > 20.1 ng/ml in 43 samples (16.6%). Gel filtration showed a predominant pattern of macroprolactinemia (> 100 kDa) in 14 (32.6%), a predominant pattern of monomeric PRL (23 kDa) in 27 (62.7%), and a variable pattern in two (4.7%). All sera with a predominant pattern of macroprolactinemia displayed anti-PRL autoantibodies by affinity chromatography for IgG. The best cut-off point for percentage of serum PRL precipitated with PEG for detection of macroprolactinemia was > or = 58.4%. Sensitivity and specificity were 100 and 96.6%, respectively. We can conclude that PEG precipitation is a convenient and simple procedure to screen for the presence of macroprolactinemia in sera from SLE patients. Precipitations > or = 58.4% are indicative of the presence of, and those < 50% the absence of, macroprolactinemia. However, samples with precipitations between 50 and 58.3% require gel filtration chromatography to characterize the predominant molecular form of PRL. Therefore, it is important to take these findings into account in future studies that aim to establish a relationship between PRL and disease activity in SLE.

Chemical Precipitation↗

PubMed1982

Identification of a major heparin-precipitable protein in human serum and its relationship to cystic fibrosis.

Heparin binding to serum proteins and their subsequent precipitation is reportedly increased in cystic fibrosis (CF). We have confirmed this finding for CF patients over the age of 12 [11.34 +/- 2.42 mg/ml precipitated protein for normals (n = 19) versus 17.46 +/- 4.60 mg/ml for CF patients (n = 37), P less than 0.001; 0.629 +/- 0.098 mg/ml precipitated heparin for normals versus 0.789 +/- 0.206 for CF patients, P less than 0.01]. We have also shown that patients with a variety of pulmonary diseases unrelated to CF do not show this effect. When the amounts of protein and heparin precipitated are compared with the amount of IgG found in the whole serum sample, the correlation coefficients (protein r = 0.77; heparin, 0.74; n = 81) are significant at a level of P less than 0.001. In addition, the report that young CF patients exhibit hypogammaglobulinemia prompted us to examine serum samples from CF patients and age-matched controls under the age of 12. No differences were found. To investigate the molecular basis for this effect, sera from patients with CF and from age-matched controls were precipitated with 50 mg% heparin at pH 5.57. Pellets resolubilized in 8 M urea were fractionated on DEAE-Sephadex and analyzed by double-immunodiffusion, SDS-PAGE, immunoelectrophoresis, and radial immunodiffusion. IgG constituted 55-56% of the eluted protein. When serum from all donors was fractionated by Staph A-Sepharose into IgG and non-IgG fractions, 85-89% of heparin precipitable protein was in the IgG fraction.

Adolescent↗

PubMed1990

On the mechanism of hydrogen peroxide formation during precipitation of hemoglobin with perchloric acid.

During acid precipitation of hemoglobin, hydrogen peroxide is formed. The oxidant is generated from hemoglobin-bound as well as from physically dissolved oxygen, provided divalent hemoglobin-iron is present. The extent of hydrogen peroxide formation seems to be dependent on the precipitating reagent. From experiments on GSH oxidation during precipitation of red cells and from a literature survey formation of at least one second reactive oxygen species has to be assumed. Different reaction pathways for generating these oxidants during acid precipitation are discussed: Hydroperoxide which is probably liberated by proton catalysis may contribute to the observed oxidation reactions. At pH approximately 1 it rapidly disproportionates yielding oxygen and hydrogen peroxide, which might produce reactive oxidants with hemoglobin intermediates formed during precipitation. In addition a new hypothesis is presented explaining the ability of N-ethylmaleimide to inhibit GSH oxidation during precipitation of red cells. Accordingly, the SH-reagent rapidly penetrates the cell membrane and reacts with GSH before access of protons prevents alkylation.

Chemical Precipitation↗

PubMed2004

Are picoplankton responsible for calcite precipitation in lakes?

Deposits of lacustrine calcite are important records of environmental changes. In order to interpret these archives, knowledge about the origin of the calcite is essential. It has been accepted that calcite precipitation can be induced by bacteria and algae. However, the detailed mechanisms are still unclear. This review summarizes what is known about the interactions between calcite precipitation and the autotrophic picoplankton. We consider findings from both field and laboratory studies. Field studies show that calcite precipitation in oligotrophic lakes is strongly linked with picocyanobacteria blooms. Laboratory experiments led to the formulation of the mechanism of precipitation induced by microalga. Experiments also showed that precipitation induced by picocyanobacteria is influenced by various factors including the uptake of inorganic carbon and the structure of the cell walls. Recent studies indicate that the influence of environmental conditions like the composition of lake water has to be taken into account as well. We conclude that in situ observations of precipitation processes at picoplankton cells under controlled conditions are needed to improve our understanding of mineral bacteria interaction.

Calcium Carbonate↗

PubMed1990

Localization of pyroantimonate-precipitable calcium in the endolymphatic sac of the tree frog, Hyla arborea japonica.

The pyroantimonate technique and a new demineralization method were employed to visualize pyroantimonate-precipitable calcium in the endolymphatic sac of the tree frog. The precipitate was determined to contain calcium (Ca) by EGTA extraction and X-ray microanalysis. The precipitate was mainly localized around calcium carbonate (CaCO3) crystals when frogs were not loaded with calcium chloride (CaCl2). When crystalline growth was accelerated by loading with CaCl2, the precipitate increased in amount, especially around the crystals and in the basement membrane (lamina rara and reticular lamina). Various degrees of precipitation were found in epithelial cells; however, neither epithelial granules nor mitochondria seemed to have a significant amount of precipitate. This study demonstrates that Ca ion accumulates around those crystals where a dense material is located. The dense material probably has an affinity for the Ca ion, and plays an important role in crystal formation. However, the transport pathway for the Ca ion into the endolymphatic lumen is still obscure.

Animals↗

PubMed1991

Localization of pyroantimonate-precipitable calcium in the vestibular organs of the rat and guinea pig.

Localization of pyroantimonate-precipitable calcium (Ca) was examined in the vestibular organs of the rat and the guinea pig. Precipitates were observed around the otoconia and in the otolithic membranes of the macula sacculi and macula utriculi. Although the deposition was heavier in the rat than in the guinea pig, the distribution of the Ca-pyroantimonate was similar in both species. Most otoconia in the dark cell area had precipitates around and inside the otoconia. Furthermore, there was some precipitation in the cupulae of the semicircular canals in both animals. The presence of Ca in the precipitates was confirmed by X-ray microanalysis and extraction with EGTA. Localization of the Ca-pyroantimonate around the otoconia in these animals agrees with localization of precipitates of endolymphatic crystals in the tree frog, which are known to grow mainly by accretion. Thus, the otoconia of the rat, and probably also of the guinea pig, can be assumed to grow mainly by accretion.

Animals↗

PubMed1992

Contents of apolipoprotein A-I, A-II and B of the human serum fractions for high-density and low-density lipoproteins prepared by common precipitation methods.

Two common precipitation methods for the determination of HDL-cholesterol in human serum were used, dextran sulphate/MgCl2 and phosphowolframate/MgCl2. They yield supernatants which contained almost all of the apoA-I and apoA-II lipoproteins but no lipoprotein apoB. The correlations between chol-HDL and apoA-I were about the same with these methods (r = 0.79 and 0.80). The correlation between the precipitation methods and ultracentrifugal analysis for chol-HDL was highly significant (r = > 0.95). Correspondingly, two common precipitation methods for the determination of LDL-cholesterol in human serum, buffered heparin, and polyvinyl sulphate procedures, produced sediments, which contained the major proportion of the apoB and only small amounts of apoA-I and apoA-II. However, yields of only 69.0-80.2% were obtained for apoB from the sediments and of 85.8-89.4% from supernatants calculated as the difference from chylomicron free serum. This difference might be due to alterations of the molecular structure of apoB by the precipitation reagents. Comparison of the results with the precipitation methods to those using the Friedewald formula showed excellent agreements (r = > 0.91). Very comparable results were also obtained in the case of marked hypertriglyceridaemia provided that the serum samples were briefly centrifuged before analysis of chol, chol-HDL, and triglyceride values for the formula of chol-LDL. The precipitation methods for chol-LDL showed very good agreement with the values obtained by ultracentrifugal analysis (r = > 0.93). There were no remarkable differences in the correlation of apoB and chol-LDL values measured by different methods (r = 0.85). According to the present results it was found that highly significant correlations existed between chol/chol-HDL or chol-LDL/chol-HDL and apoB/apoA-I ratios (p < 0.001). It is quite evident that apoB and apoA-I values could be used to replace chol-LDL and chol-HDL values when the risk for the cardiovascular diseases is to be assessed.

Apolipoprotein A-I↗

PubMed1981

Precipitation of oxyhemoglobins A and S by isopropanol.

The isopropanol precipitation test is widely used for the detection of unstable hemoglobins. A method for accurately and easily determining the amount of hemoglobin precipitated is described. This study demonstrates that changes in incubation time, pH, temperature, and isopropanol and hemoglobin concentrations affect the precipitation of oxy Hb A and oxy Hb S. Hb S shows greater precipitation than Hb A with increasing time, temperature, and isopropanol concentrations. Both hemoglobins show equal increases in precipitation, with increases and decreases in pH and decreases in hemoglobin concentration. Comparison of the isopropanol precipitation test with the mechanical shake and heat denaturation tests reveals that the mechanical shake test is the easiest method to study the stability of Hbs A and S. Each of the tests may measure different parameters of stability. The use of all three tests in the evaluation of unstable hemoglobins should be considered.

1-Propanol↗

PubMed1999

Macroamylase detection in serum using selective precipitation: a rapid and reliable assay.

BACKGROUND AND AIM: Available assays for measurement of pancreatic isoamylase in serum based on specific immunoinhibition of salivary fraction are unable to detect macroamylase. We combined a polyethylene glycol test which identifies macroamylase by selective precipitation with an automated assay for total amylase and pancreatic isoamylase measurement. METHODS: We analysed 24 sera proven positive for macroamylase using gel filtration chromatography and 80 negative sera. Precipitation of macroamylase with polyethylene glycol, colourimetric measurement of total amylase activity and immunoinhibition for the determination of pancreatic isoamylase were carried out. RESULTS: Macroamylasaemic sera showed precipitation of at least 71% of the amylase activity, while sera with normal-sized amylase exhibited a maximum of 61%. In all the macroamylasaemic sera but two, the immunoinhibition test showed a rise in pancreatic isoamylase, which was found to be the prevalent fraction in 16. In 21 out of 24 sera with macroamylase and 67 out of 80 with normal-sized amylase, the precipitated amylase activity was also measured after immunoinhibition of non pancreatic activity. In macroamylasaemic sera, the percentage of precipitated pancreatic isoamylase activity ranged from 75% to 98%, while in samples with normal-sized amylase it was less than 71%. CONCLUSIONS: Polyethylene glycol precipitation can easily be combined with automated assays for the determination of pancreatic isoamylase and should be carried out whenever dealing with hyperamylasaemia of unclear origin.

Amylases↗

PubMed1979

Precipitation of streptococcal peptidoglycan by human sera: influence of anti-immunoglobulins.

Antibodies to streptococcal peptidoglycan (PG) were detected by gel-precipitation in 38% of sera from blood donors and in 71% of sera with a Waaler-Rose test titre of greater than or equal to 1:64. Twenty-six rheumatoid arthritis sera revealed patterns of interference with complete or partial fusion between PG and aggregated human IgG while none of the sera precipitating both these preparations showed non-interference. The reactions were interpreted as denoting interference between the PG-antibody complexes and aggregated IgG. Conversion of some non-precipitating blood donor sera to PG precipitation was obtained by addition of isolated rheumatoid factor, in itself not precipitating PG, to the sera. Thus, the high frequency of PG precipitation among rheumatoid arthritis sera could--at least in part--be attributed to the participation of anti-IgG in the reaction.

Antibodies, Anti-Idiotypic↗

PubMed2000

Measurement of apolipoprotein B concentration in plasma lipoproteins by combining selective precipitation and mass spectrometry.

The measurement of apolipoprotein B (apoB) in purified lipoproteins by immunological assays is subject to criticism because of denatured epitopes or immunoreactivity differences between purified lipoproteins and standard. Chemical methods have therefore been developed, such as the selective precipitation of apoB followed by quantification of the precipitate. In this study, we present the measurement of apoB concentration in lipoproteins purified by ultracentrifugation by combining isopropanol precipitation and gas chromatography/mass spectrometry. Very low density lipoprotein (VLDL; d < 1.006 g/mL); VLDL plus intermediate density lipoprotein (VLDL + IDL; d < 1.019 g/mL); and VLDL, IDL, and low density lipoprotein (VLDL + IDL + LDL; d < 1.063 g/mL) were purified by ultracentrifugation. Apolipoprotein B-100 was selectively precipitated by isopropanol. The leucine content of the pellet was then determined by gas chromatography/mass spectrometry, using norleucine as internal standard. Knowledge of the number of leucine molecules in one apoB-100 molecule makes it possible to calculate the plasma concentration of apoB in the various lipoprotein fractions. ApoB in IDL (d 1.006-1.019 g/mL) and LDL (d 1.019-1.063 g/mL) were then determined by subtracting VLDL-apoB from apoB in lipoproteins d < 1.019 and apoB in lipoproteins d < 1.019 g/mL from apoB in lipoproteins d < 1.063 g/mL, respectively. The isopropanol precipitate was verified as pure apoB (>97%) in lipoprotein fractions isolated from normo- and hyperlipidemic plasma and the method appeared reproducible. The combination of isopropanol precipitation and the GC/MS method appears therefore to be a precise and reliable method for kinetic and epidemiological studies.

2-Propanol↗

PubMed2002

Assessment of magnesium ammonium phosphate precipitation for the treatment of leather tanning industry wastewaters.

Magnesium ammonium phosphate (MAP) precipitation has a potential for ammonium removal from industrial wastewaters. Application basis of this recent method of treatment has not been fully determined. In this study application of MAP precipitation to leather tanning wastewaters has been experimentally evaluated. Five alternative places of MAP precipitation in leather tanning wastewater treatment scheme tested were; instead of plain settling, after plain settling, after polyelectrolyte added plain settling, within the chemical precipitation and after biological treatment. Among these alternatives MAP application instead of plain settling and within the chemical precipitation were found to be most favourable and efficient by reducing the nitrogen load to the level of nutrient requirement in the biological stage. pH 9.0-9.5 and stoichiometric magnesium and phosphate doses were determined to be optimum conditions for MAP precipitation.

Chemical Precipitation↗

PubMed2001

[Determination of trace Sn in geosamples by flow injection on-line co-precipitation hydride generation atomic fluorescence spectrometry].

It is reported that a FI on-line co-precipitation technique for the pre-concentration of trace amount of Sn with the precipitate of Mg(OH)2 as carrier is hyphenated with AFS determination. The co-precipitation is carried out in NaOH medium and the precipitate is collected in a precipitation collector. The precipitate is then dissolved by HCl and reacted with NaBH4, the hydride is transferred directly into the atomizer. The relative standard deviation is 5.15% for 10 determinations of 30 ng.mL-1 Sn and the detection limit of 0.21 ng.g-1 is obtained. The developed method has been applied to the determination of trace Sn in geosamples with satisfactory results.

Chemical Precipitation↗

PubMed2004

Co-removal of hexavalent chromium through adsorption during copper precipitation.

A systematic study was conducted to assess the mechanisms involved in the co-removal of hexavalent chromium during chemical precipitation of divalent copper. Batch tests were used to assess the precipitation phenomena in both pure copper solutions and also mixed copper-Cr(VI) solutions with progressive addition of sodium carbonate to increase pH and induce precipitation. It was found that the co-removal of Cr(VI) was caused by two distinct mechanisms: coprecipitation of copper with Cr(VI) at pH 5.0 to 5.2, leading to the formation of CuCrO4 precipitates. Once the fine crystallites of CuCrO4 were formed, the test solution became heterogeneous and this accelerated the production of copper-carbonate precipitates, mainly in the form of CuCO3 Cu(OH)2, at pH 5.2 to 6.2. The latter precipitates were negatively charged at pH below 7.5, and thus they were able to adsorb a considerable amount of the remaining chromate ions [HCrO4- and CrO4(2-)]. The extent of adsorption depended on both pH and surface loading. Besides electrostatic attraction, ligand exchange was also found to play some role. Maximum adsorption occurred at pH 6.5. When pH was raised to 10.0, approximately 25-30% of the adsorbed chromium could become desorbed due to a surface charge reversal on the adsorbent.

Adsorption↗

PubMed2005

Evaluation of Western blotting methods using samples with or without sodium phosphotungstic acid precipitation for diagnosis of scrapie and chronic wasting disease.

The purpose of this study was to enhance the sensitivity of the Western blot (WB) test for use as an alternative and confirmatory method for the diagnosis of scrapie and chronic wasting disease (CWD) in Canada by comparing 2 sample preparation procedures: an abnormal prion protein (PrPSc) concentration procedure using sodium phosphotungstic acid (PTA) precipitation and a procedure using crude sample without precipitation. A total of 100 cerebrum samples (52 sheep and 48 elk), including 66 negative (31 sheep, 35 elk) and 34 positive (21 scrapie and 13 CWD positive) samples diagnosed by using immunohistochemistry (IHC) on retropharyngeal lymph node (RPLN) and medulla oblongata at obex, were tested by using WB with the 2 sample preparation procedures. The WB using non-PTA enriched sample (crude extract) detected, on average, only 71.7% (9 of 15, 60.0% for scrapie, 5 of 6, 83.3% for CWD) of the samples that tested positive by using WB with PTA enriched samples. No case was positive by WB using crude extract but negative by WB using PTA enriched sample. No false positive was found. Serial dilution of PTA precipitated samples demonstrated that the technique increases the detection limit approximately 100 fold. Additionally, the comparison of the WB and IHC on cerebrum from all the positive cases demonstrated that WB following PTA precipitation and IHC had 100% agreement by detecting 6 positive for CWD on cerebrum; while IHC detected scrapie in only 14 out of 15 positive cerebrum samples by using WB following PTA precipitation. Phosphotungstic acid precipitation is therefore a useful adjunct to WB analysis of scrapie and CWD and tissues.

Animals↗

PubMed1975

Observations on the mechanical precipitation of oxy Hb S and other mutants.

Oxyhemoglobin S exhibits greater mechanical instability than oxyhemoglobin A. The rate of precipitation of Hb S when agitated by vortexing depends upon the geometry of the tube, the volume of the hemoglobin solution, and the concentration of hemoglobin. The rate of precipitation is inversely related to concentration. Precipitation is inhibited by temperatures near 4 degrees C and alkylureas whose protective capacity is approximately proportional to the carbon chain length of the alkyl group. Blocking the beta93 -SH group with parahydroxymercuribenzoate has only a small enhancing effect on the precipitation rate. Other mutants such as Hb Gun Hill, Leiden, (both heat unstable), and C-HARLEM are also unstable. In the case of C-HARLEM, the precipitation rate is greater than that for Hb S. The heat-unstable mutants are not as well protected by cold temperatures or alkyl ureas. D2O has only a minor stabilizing effect on hemoglobin S, but NaCl and related salts markedly enhance precipitation at concentrations of 0.5 M. It is concluded that mechanical instability of oxyhemoglobins is a multifactorial process involving surface denaturation, pH, ionic strength, hydrophobic interactions, protein conformation, and primary protein structure. This phenomenon will require more extensive investigation.

Carbon Radioisotopes↗

PubMed1989

Water-induced precipitation of cholesterol dissolved in organic solvents in the absence and presence of surfactants and salts.

The precipitation of cholesterol dissolved in organic solvents, viz. methanol, ethanol, n-propanol, isopropanol, acetone and 1,4-dioxane, by the addition of water has been studied. The effects of the solvents towards the precipitation follow the order: methanol greater than ethanol greater than acetone greater than dioxane greater than n-propanol greater than iso-propanol, the solvent dioxane however exhibits a change in the order at higher concentration. Additives like Triton X-100, sodium cholate, sodium deoxycholate, sodium dehydro cholate, sodium salicylate and sodium chloride have some protective action against precipitation, the maximum protection being that of Triton X-100. The additives have shown better protective action in propanols and dioxane than in methanol, ethanol and acetone. Analysis of solvent composition and dielectric constant has revealed specific solvent effects on the water-induced precipitation of cholesterol. Thermodynamic analysis of the precipitation phenomenon and the unique role of solvent structure on cholesterol precipitation has been discussed.

Bile Acids and Salts↗

PubMed1985

Prevention of immune precipitation by purified components of the alternative pathway.

The role of the alternative pathway in complement-mediated prevention of immune precipitation has been investigated by the use of BSA-anti-BSA immune complex (IC) purified components. For immune precipitation to be prevented all six alternative pathway components (C3, factors B D, P, H and I) were required. In the absence of one or both of the control proteins H and I, excessive fluid phase turnover of C3 occurred with precipitation of IC. Kinetic studies showed that in the presence of the control proteins, an initial phase of precipitation occurred, and was followed by a phase of resolubilization of IC. When the efficiency of classical and alternative pathways in the prevention of immune precipitation was compared it was found that the classical pathway proteins were more effective than the alternative pathway components. A reaction mixture containing the components of both pathways was no better than the classical pathway protein alone. 125I-C3 was bound to IC which had been rendered soluble in the presence of classical or alternative pathway components. A molar ratio of two molecules C3b:five molecules IgG was calculated. Other complement components which were bound to IC which had been formed in the presence of serum were C1q, C4, C2, C3, C5, P and H. Factors B and I were not detected. Our findings suggest that the alternative pathway is of secondary importance to the classical pathway in the prevention of immune precipitation.

Antigen-Antibody Complex↗