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PubMed2001

Liposomes labeled with biotin and horseradish peroxidase: a probe for the enhanced amplification of antigen--antibody or oligonucleotide--DNA sensing processes by the precipitation of an insoluble product on electrodes.

Liposomes labeled with biotin and the enzyme horseradish peroxidase (HRP) are used as a probe to amplify the sensing of antigen-antibody interactions or oligonucleotide-DNA binding. The HRP-biocatalyzed oxidation of 4-chloro-1-naphthol (1) in the presence of H2O2, and the precipitation of the insoluble product 2 on electrode supports, are used as an amplification route for the sensing processes. The anti-dinitrophenyl antibody (DNP-Ab) is sensed by a dinitrophenyl-L-cysteine antigen monolayer associated with an Au electrode. A biotinylated anti-IgG-antibody (Fc-specific) is linked to the antigen-DNP-Ab complex, and the biotin-labeled HRP-liposomes associate with the assembly through an avidin bridge. The biocatalyzed precipitation of 2 on the electrode increases the electron-transfer resistances at the electrode-solution interface or the electrode resistance itself. The binding events of the different proteins on the electrode and the biocatalyzed precipitation of 2 on the conductive support are followed by Faradaic impedance spectroscopy or constant-current chronopotentiometry. DNP-Ab concentrations as low as 1 x 10(-11) g x mL(-1) can be detected by this method. The labeled liposomes were also used for the amplified detection of DNA 3. The oligonucleotide 4, complementary to a part of the target DNA 3 that is a model nucleic acid sequence for the Tay-Sachs genetic disorder, is assembled on an Au electrode. Hybridization of the analyte 3 followed by the association of the biotin-tagged oligonucleotide 5 yields a three-component double-stranded assembly. Sensing of the analyte 3 is amplified by the association of avidin, the labeled liposomes, and the subsequent biocatalyzed precipitation of 2 on the electrodes. The DNA 3 is detected with a sensitivity that corresponds to 6.5 x 10(-13) M. Faradaic impedance spectroscopy and chronopotentiometry were employed to follow the stepwise assembly of the systems and the electronic transduction of the detection of the analyte DNA 3.

Antigen-Antibody Reactions↗
PubMed2003

Use of a water-soluble fullerene derivative as precipitating reagent and matrix-assisted laser desorption/ionization matrix to selectively detect charged species in aqueous solutions.

A starlike water-soluble fullerene derivative, hexa(sulfonbutyl)fullerene (C60[(CH2)4SO3-]6; HSBF), consisting of a C60 cage covalently bonded with six negatively charged sulfonate arms, was synthesized and used to selectively precipitate positively charged surfactants, amino acids, peptides, and proteins. The affinity of HSBF to the analytes depends on the charge, structure, and hydrophobic characteristics of the analytes. The ion pair precipitate was easily removed from the solution by centrifugation. After washing, the precipitate was redissolved in the solvent or buffer solution and the analyte was characterized by laser desorption ionization-time-of-flight mass spectrometry (LD-TOF). HSBF shows strong optical absorbance in the UV range, so no additional organic matrix was required to conduct LD-TOF analysis of small analytes. For the solution that contained five quaternary amines differing only in alkyl chain length, HSBF exhibits the highest affinity to the amine with the longest alkyl chain. Only the arginine signal was detected from the solution that contained 14 amino acids. The peptides with arginine as the end groups interacted most strongly with HSBF and could be selectively precipitated from a solution of a mixture of five peptides. The signals associated with a trace amount of charged peptides derived from the digestion of proteins by trypsin were greatly enhanced after concentration with HSBF. Among eight proteins in the sample solution, insulin had the strongest affinity to the HSBF and exhibited the strongest signal on the matrix-assisted laser desorption/ionization mass spectrum.

Amino Acid Sequence↗
PubMed2005

Octadecyl immobilized surface for precipitate collection with a renewable microcolumn in a lab-on-valve coupled to an electrothermal atomic absorption spectrometer for ultratrace cadmium determination.

Octadecyl immobilized surface was, for the first time, proved to be a superb precipitate-collecting medium. Surface charge effect was assumed to dominate the adsorption of cadmium hydroxide precipitate, facilitated by electrostatic interaction between the negatively charged C18 bead surface and positively charged cadmium hydroxide clusters. Residual silanol groups on the C18-immobilized silica surface did not contribute to precipitate adsorption. A novel procedure for ultratrace cadmium preconcentration was proposed by incorporating a renewable microcolumn in a lab-on-valve system. Cd(OH)(2) precipitate was adsorbed onto the C18 surface, which was afterward eluted with 20 microL of nitric acid (1%) and quantified with detection by electrothermal atomic absorption spectrometry. An enrichment factor of 28 and a limit of detection of 1.7 ng L(-1), along with a sampling frequency of 13 h(-1) were obtained with a sample consumption of 600 microL within the concentration range of 0.01-0.2 microg L(-1), achieving a precision of 2.1% RSD at the 0.05 microg L(-1) level. The enrichment factor was further enhanced to 44 by increasing the sample volume to 1200 microL. The procedure was validated by analyzing cadmium in three certified reference materials, that is, river sediment (CRM 320), sea lettuce (CRM 279), and frozen cattle blood (GBW 09140). Good agreement between the obtained results and the certified values was achieved.

Absorption↗
PubMed1988

Precipitation of galactose-specific lectins by complex-type oligosaccharides and glycopeptides: studies with lectins from Ricinus communis (agglutinin I), Erythrina indica, Erythrina arborescens, Abrus precatorius (agglutinin), and Glycine max (soybean).

We have recently demonstrated that certain oligomannose and bisected hybrid type glycopeptides and bisected complex type oligosaccharides are bivalent for binding to concanavalin A and can precipitate the lectin [Bhattacharyya, L., Ceccarini, C., Lorenzoni, P., & Brewer, C.F. (1987) J. Biol. Chem. 262, 1288-1293; Bhattacharyya, L., Haraldsson, M., & Brewer, C.F. (1987) J. Biol. Chem. 262, 1294-1299]. The present results show that tri- and tetraantennary complex type oligosaccharides containing nonreducing terminal galactose residues, and a related triantennary glycopeptide, precipitate the D-galactose-specific lectins from Ricinus communis (agglutinin I) (RCA-I), Erythrina indica (EIL), Erythrina arborescens (EAL), and Glycine max (soybean) (SBA). Nonbisected and bisected biantennary complex type oligosaccharides can precipitate SBA, which is a tetrameric lectin, but not RCA-I, EIL, or EAL, which are dimeric lectins. The relative affinities of the oligosaccharides and glycopeptide were determined by hemagglutination inhibition measurements and their valencies by quantitative precipitin analyses. The equivalence points of the precipitin curves indicate that the tri- and tetraantennary oligosaccharides are tri- and tetravalent, respectively, for EIL, EAL, and SBA binding. However, the oligosaccharides are all trivalent for RCA-I binding due apparently to the larger size of the monomeric subunit of the lectin. The triantennary glycopeptide was also trivalent for RCA-I and EIL binding. Biantennary oligosaccharides with adequate chain lengths were found to be bivalent for binding to SBA; those with shorter chains did not precipitate the lectin.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate Conformation↗
PubMed2001

129I from the nuclear reprocessing facilities traced in precipitation and runoff in northern Europe.

A huge amount of radioactive 129I has been released into the environment from the nuclear energy industry, atomic weapon tests, and nuclear accidents. In this study, we present weekly and seasonal data on 129I measured in precipitation and runoff of northern Europe during 1998 and 1999. The 129I concentration is at 10(8)-10(9) atoms/L in precipitation and (2-5) x 10(8) atoms/L in runoff water, and it is 3-4 orders of magnitude higher than in the prenuclear era. Snow shows lower 129I concentration than rain, and there is apparently a positive correlation between surface air temperature and 129I. Precipitation chemistry, expressed as the content of Cl, SO4, and NO3 and atmospheric ozone, exhibits weak negative correlation with 129I values. Our 129I data on precipitation suggest significant influence of the northern European atmosphere by the discharges from the nuclear reprocessing facilities at Sellafield and La Hague.

Europe↗
PubMed2001

Time scales for sorption-desorption and surface precipitation of uranyl on goethite.

The sorption of uranium on mineral surfaces can significantly influence the fate and transport of uranium contamination in soils and groundwater. The rates of uranium adsorption and desorption on a synthetic goethite have been evaluated in batch experiments conducted at constant pH of 6 and ionic strength of 0.1 M. Adsorption and desorption reactions following the perturbation of initial states were complete within minutes to hours. Surface-solution exchange rates as measured by an isotope exchange method occur on an even shorter time scale. Although the uranium desorption rate was unaffected by the aging of uranium-goethite suspensions, the aging process appears to remove a portion of adsorbed uranium from a readily exchangeable pool. The distinction between sorption control and precipitation control of the dissolved uranium concentration was also investigated. In heterogeneous nucleation experiments, the dissolved uranium concentration was ultimately controlled by the solubility of a precipitated uranyl oxide hydrate. The X-ray diffraction pattern of the precipitate is characteristic of the mineral schoepite. Precipitation is kinetically hindered at low degrees of supersaturation. In one experiment, metastable sorption controlled dissolved uranium concentrations in excess of the solubility limit for more than 30 d.

Adsorption↗
PubMed2006

Annual variation of polycyclic aromatic hydrocarbon concentrations in precipitation collected near the Great Lakes.

Polycyclic aromatic hydrocarbon (PAH) concentrations were measured in precipitation samples collected from 1997 to 2003 at seven sites near the Great Lakes as a part of the Integrated Atmospheric Deposition Network. The 28-day integrated concentrations of most PAHs showed significant seasonal trends with higher concentrations in the winter and lower concentrations in the summer. Long-term decreasing trends were observed for all PAHs measured in precipitation at Chicago. At the sites on Lakes Superior, Michigan,,and Erie, most PAHs did not show significant long-term trends. At the two Canadian sites on Lakes Huron and Ontario, lower molecular weight PAHs (e.g., fluorene to pyrene) showed long-term decreasing trends; however, no long-term trends were observed for higher molecular weight PAHs at these sites. Interestingly, retene, a marker for wood burning, showed increasing trends at the sites on Lakes Superior and Michigan. For all the other PAHs, precipitation collected at Chicago had by far the highest PAH concentrations followed by the site on Lake Erie. Generally, the Lake Superior sites had the lowest PAH concentrations. However, retene concentrations in precipitation collected at the Lake Superior site were higher compared to Lakes Michigan and Erie, which indicate more residential wood burning in the far north of the Great Lakes basin.

Air Pollutants↗
PubMed2006

Temporal trends of polychlorinated biphenyls in precipitation and air at chicago.

Polychlorinated biphenyl (PCB) concentrations in precipitation (1997-2003) and in the atmospheric gas phase (1996-2003) collected in Chicago, IL, are reported. These data were obtained as part of the Integrated Atmospheric Deposition Network. For comparison, PCB concentrations at a remote site, Sleeping Bear Dunes on the northeastern shore of Lake Michigan, are also reported. Much higher PCB concentrations in both precipitation (7.1 +/- 0.9 ng/L) and the gas phase (1.4 +/- 0.1 ng/m3) at Chicago compared to Sleeping Bear Dunes (1.1 +/- 0.1 ng/L and 0.1 +/- 0.08 ng/m3, respectively) indicate that Chicago is a source of PCBs to the Great Lakes. A long-term decreasing trend of PCB concentrations in precipitation was observed at Chicago with a half-life of 6.8 +/- 3.1 years. The corresponding half-life for PCB concentrations in the gas phase was 7.7 +/- 1.1 years. The significant long-term decrease of PCB concentrations in precipitation and the gas phase in Chicago suggests that regulatory efforts are working, at least in this city.

Air Pollutants↗
PubMed2004

Automatic and subsequent dissolution and precipitation process in inorganic macroionic solutions.

We report an interesting phenomenon in the NaCl-containing aqueous solution of {Mo72Fe30} macroions, where dissolution and precipitation processes of hydrophilic macroions automatically and subsequently occur without changing external conditions or chemical reactions. Our previous work indicates that {Mo72Fe30} macroions tend to slowly self-assemble into single-layer, vesicle-like "blackberries". Such macroions have two solute states in solutions: the entropy-favored general state (homogeneous distribution) and the free-energy favored second solute state (blackberries). With additional salts, the originally stable blackberries become less stable due to their shortened screening length, and they tend to further aggregate and precipitate at much lower concentrations. Therefore, in such a solution, we can observe a subsequent process: crystal solids --> homogeneous single macroion solution --> homogeneous blackberry solution --> precipitates containing noncrystalline solids. In other words, we observed the behaviors of both soluble inorganic ions and colloids in the same solution due to the unique features of the macroions. Static and dynamic laser light scattering, as well as AFM measurements, were used to characterize both the macroionic solutions and the precipitates.

Journal Article↗
PubMed2004

Brewster angle microscopy of calcium oxalate monohydrate precipitation at phospholipid monolayer phase boundaries.

The precipitation of calcium oxalate monohydrate (COM) at phospholipid monolayers confined to the air/water interface is observed in situ with the aid of Brewster angle microscopy. COM crystals appear as bright objects that are easily identified and quantified to assess the effects of different conditions on crystallization. Crystal precipitation was monitored at monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in liquid condensed (LC) and liquid expanded (LE) phases. Within the LC phase, higher pressures reduce the incidence of crystallization at the interface, implying that within this phase precipitation is enhanced by higher compressibility or fluidity of the monolayer. Precipitation at biphasic LC/LE and LE/gas (G) monolayers was also studied. COM appears preferentially at phase boundaries of the DPPC LC/LE and LE/G monolayers. However, when an LC/LE phase boundary is created by two different phospholipids that are phase segregated, such as DPPC and 1,2-dimyristoyl-sn-glycero-3-phosphocholine, crystal formation occurs away from the interface within the DPPC LC phase. It is suggested that COM growth at phase boundaries is preferred only when there is molecular exchange between the phases.

Calcium Oxalate↗
PubMed2005

Precipitative growth templated by a fluid jet.

Tubular growth by chemical precipitation at the interface between two fluids, a jet and its surroundings, underlies the development of such important structures as chimneys at hydrothermal vents. This growth is associated with strong thermal and/or solute gradients localized at those interfaces, and these gradients, in turn, often produce radial compositional stratification of the resulting tube wall. A fundamental question underlying these processes is how the interplay between diffusion, advection, and precipitation determines the elongation rate of the tubes. Here we report experimental and theoretical results that reveal a regime in which there exists a new scaling law for tube growth. The model system studied consists of a jet of aqueous ammonia injected into a ferrous sulfate solution, precipitating iron hydroxides with varying oxidation states at the jet boundary. Despite the complex chemistry and dynamics underlying the precipitation, the tube growth exhibits a strikingly simple scaling form, with characteristic lengths and times increasing linearly with the mean velocity of the jet. These observations follow from a kinetic model of advection-dominated flows.

Letter↗
PubMedDate not supplied

Affinity precipitation of monoclonal antibodies by nonstoichiometric polyelectrolyte complexes.

The nonstoichiometric polyelectrolyte complex (PEC) formed by poly(methacrylic acid) (degree of polymerization 1830) (PMAA) and poly(N-ethyl-4-vinyl-pyridinium bromide) (degree of polymerization 530) (PEVP) undergoes reversible precipitation from aqueous solution at any desired pH-value in the range 4.5-6.5 depending on the ionic strength and PEVP/PMAA ratio in the complex. The antigen, inactivated glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from rabbit was covalently coupled to PEVP. The resulting GAPDH-PEVP/PMAA complex was used for the purification of antibodies from a 6G7 clone specific towards inactivated GAPDH. The crude extract was incubated with GAPDH-containing PEC and the precipitation of the PEC was carried out at 0.01 M NaCl and pH 4.5, 5.3, 6.0 and 6.5 using PEC with PEVP/PMAA ratios of 0.45, 0.3, 0.2 and 0.15, respectively. Purified antibodies were eluted at pH 4.0 where PECs of all compositions used were insoluble. PEC precipitation is accompanied only by small nonspecific coprecipitation of proteins. Precipitated PEC could be dissolved at pH 7.3 and used repeatedly.

Animals↗
PubMed2002

Age-hardening behaviors and grain boundary discontinuous precipitation in a Pd-free gold alloy for porcelain bonding.

Isothermal age-hardening behaviors at 400 degrees and 450 degrees C and discontinuous precipitation reaction at 450 degrees C in a commercial Pd-free gold alloy for porcelain bonding were investigated by hardness testing, X-ray powder diffraction, and light microscopy. Variations of electrical resistivity during continuous heating and cooling processes were also measured. The alloy exhibited pronounced age-hardening in the early stage of aging and the maximum hardness exceeded twice that of the solution-treated sample. Precise lattice parameter measurements and investigations of full width at half maximum values for the X-ray Bragg reflections implied that nonuniform strains due to the pre-precipitation or zone formation was responsible for the quick and pronounced age-hardening at 450 degrees C. Discontinuous precipitation reaction, producing a mixture of a small amount of Pt(3)In-phase with the L1(2)-type superstructure and a large amount of (Pt, In)-depleted solid solution, started at grain boundaries in the late stage of aging process at 450 degrees C. The growth of the grain boundary discontinuous precipitates toward the intragrain area led to a gradual decrease in hardness of the alloy.

Journal Article↗
PubMed2001

Solid-phase precipitation and extraction, a new separation process applied to the isolation of synthetic peptides.

A new method for separation and purification is described. The process, referred to as solid-phase precipitation and extraction (SPPE), was developed and applied to postcleavage isolation of synthetic peptides. The technique uses normal approaches of chromatography and solid-phase extraction sorbents with a precipitation or drying procedure so that the sorbent becomes a support matrix for thin-film deposition of the compounds of interest. This procedure causes precipitated compounds of interest to be trapped on the large surface area or in the pores of the matrix so that by-products and impurities can be removed by strong wash solvents. In application to solid-phase peptide synthesis chemistry, by-products from the cleavage and deprotection are selectively extracted from the crude sample mixture under mild conditions. In comparison to the ether precipitation method used in peptide chemistry, the SPPE process provides isolated products that are 14-17% (w/w) higher purity.

Amino Acid Sequence↗
PubMed2003

Coupled spatial variations in precipitation and long-term erosion rates across the Washington Cascades.

Past studies of tectonically active mountain ranges have suggested strong coupling and feedbacks between climate, tectonics and topography. For example, rock uplift generates topographic relief, thereby enhancing precipitation, which focuses erosion and in turn influences rates and spatial patterns of further rock uplift. Although theoretical links between climate, erosion and uplift have received much attention, few studies have shown convincing correlations between observable indices of these processes on mountain-range scales. Here we show that strongly varying long-term (>10(6)-10(7) yr) erosion rates inferred from apatite (U-Th)/He cooling ages across the Cascades mountains of Washington state closely track modern mean annual precipitation rates. Erosion and precipitation rates vary over an order of magnitude across the range with maxima of 0.33 mm yr(-1) and 3.5 m yr(-1), respectively, with both maxima located 50 km west (windward) of the topographic crest of the range. These data demonstrate a strong coupling between precipitation and long-term erosion rates on the mountain-range scale. If the range is currently in topographic steady state, rock uplift on the west flank is three to ten times faster than elsewhere in the range, possibly in response to climatically focused erosion.

Journal Article↗
PubMed2002

Predisposing and precipitating factors for falls among older people in residential care.

Falls and their consequences are serious health problems among older populations. To study predisposing and precipitating factors for falls among older people in residential care we used a cross-sectional study design with a prospective follow up for falls. Fifty-eight women and 25 men, with a mean age of 79.6 y, were included and prospectively followed up regarding falls for a period of 1 y after baseline assessments. All those who fell were assessed regarding factors that might have precipitated the fall. The incidence rate was 2.29 falls/person years. Antidepressants (selective serotonin reuptake inhibitors, SSRIs), impaired vision and being unable to use stairs without assistance were independently associated with being a 'faller'. Twenty-eight (53.8%) of the fallers suffered injuries as a result of their falls, including 21 fractures. Twenty-seven percent of the falls were judged to be precipitated by an acute illness or disease and 8.6% by a side effect of a drug. Acute symptoms of diseases or drug side effects were associated with 58% of the falls which resulted in fractures. We conclude that SSRIs seem to constitute one important factor that predisposes older people to fall, once or repeatedly. Since acute illnesses and drug side-effects were important precipitating factors, falls should be regarded as a possible symptom of disease or a side-effect of a drug until it is proven otherwise.

Accidental Falls↗
PubMed1999

Carbonate induced dissolution of uranium containing precipitates under cement leachate conditions.

The effects of carbonate on uranium (VI) solubility under aerobic and cementitious conditions have been investigated. The information is of relevance to low level nuclear waste disposal. Aqueous NaOH, KOH, Ca(OH)2 and a cement leachate solution were added to uranyl nitrate solution. Afterwards, increasing amounts of ammonium carbonate were added to re-dissolve the precipitates. The precipitates were characterised by means of X-ray powder diffraction (XRPD) measurements and modelling studies. The model calculations were performed using the MINTEQA2 speciation code, with an expanded database incorporating uranium stability constants taken from the HATCHES database. The measured and predicted amounts of CO3(2-) needed to dissolve the precipitates were compared. The knowledge gained from the 'pure' systems was used to rationalise the precipitation and re-dissolution behaviour observed in the leachate system. The lack of uranium solubility at low carbonate levels brought into question literature formation constants for UO2(OH)3- and UO2(OH)4(2-). An approximate log K value of 26.8 for K2U2O7 formation was estimated from the KOH results at pH 12. Generally, uranium solubilities are expected to be insignificant at low level nuclear waste sites because anaerobic conditions should persist. However, this study has demonstrated that solubility in leachate could rise at high pH and high carbonate levels, if aerobic conditions were to develop. Soluble U(VI) species would be formed. The novel part of the study has been to reproduce the effects and to correlate enhanced solubilities with model predictions. Consequently, the study has re-emphasised the need for appropriate environmental monitoring of such sites.

Carbonates↗
PubMed1997

A simple monoclonal antibody based ELISA for free protein S. Comparison with PEG precipitation.

A simple monoclonal antibody based ELISA for free Protein S, compatible with out existing ELISA for total Protein S has been developed, and its performance compared with the conventional PEG precipitation method of free Protein S assay. The normal range (mean +/- 2 SD) was 0.19-0.54 iu/ml free Protein S. The mean intra assay variation was 5.24% and the mean inter assay variation was 5.50%. A total of 102 routine diagnostic samples from patients referred for prothrombotic investigation (six assays for each method) were assayed by PEG precipitation (mean 0.32 iu/ml, SD 10.60), and the monoclonal ELISA (mean 0.34, SD 0.9). Paired t-test analysis of the two data sets indicated no significant difference between them (P < 0.001). In this sample population, there was no significant difference in free Protein S values when assayed by monoclonal based ELISA or by PEG precipitation. The monoclonal assay has proved to be reliable, accurate and precise. The monoclonal ELISA is simpler, quicker and easier to perform in routine use. Data generated is directly comparable to that generated by PEG precipitation. This methodology would be suitable for laboratories currently measuring Protein S by ELISA.

Analysis of Variance↗