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At least 631 records · Page 35Linked to original sources

PubMed1976

Non-precipitating guinea-pig antibodies as products of limited recognition of antigenic sites on the ovalbumin molecule.

The non-precipitating guinea-pig IgG1 and IgG2 antibodies, produced by administration of an excessive dose of hen ovalbumin (OA), were capable of forming only certain soluble complexes having molar ratios of antibody to antigen lower than 1-5:1, which were lower than the minimum ratio of 2-5:1 shown by anti-OA antibodies precipitable with OA. This unusual property of the non-precipitating antibodies was caused by a limited number of antibody molecules capable of binding to one OA molecule simultaneously, since the maximum number of their Fab' fragments binding to one OA molecule was only three and markedly less than the number (7-8) of Fab' fragments of the precipitating IgG1 and IgG2 anti-OA antibodies binding to one OA molecule. These results demonstrate that the non-precipitating IgG1 and IgG2 anti-OA antibodies are those reacting with some particular antigenic sites on OA, a number of the antigenic sites too few to permit insoluble lattice formation.

Animals↗

PubMed1980

Pre-precipitated and solid-phase second antibody compared in radioimmunoassay.

We describe simple methods for preparing and determining the titer of pre-precipitated second antibody. We compared the performance of this type of insolubilized second antibody with that of a commercially available solid-phase second antibody (DASP) for separation of reverse triiodothyronine (rT3) and for thyrotropin radioimmunoassays. Equilibrium time for both reagents was about 30 min, considerably briefer than for the usual second-antibody procedure. Within-assay precision was improved and percentages of nonspecific binding (mean and SD) were lower if pre-precipitated second antibody was used in both assays [rT3 pre-precipitate = 1.48 (SD 0.16), rT3 DASP = 3.76 (SD 0.22); thyrotropin pre-precipitate = 1.45 (SD 0.18), thyrotropin DASP = 3.45 (SD 0.26)]. The cost of DASP was three to 10 times that of pre-precipitated second antibody prepared with commercially available products.

Antibodies↗

PubMed1978

Precipitate labour.

In Turku University Central Hospital there were 4976 deliveries in the years 1974--75. Among them there were 106 spontaneous, nonaugmented labours with a duration of two hours or less, giving an incidence of 2.1% precipitate labour. The most important aetiological factor was multiparity. 35% of precipitate labours commenced with spontaneous rupture of the membranes. The incidence of prematurity after precipitate labour was 8.5% and thus significantly (p less than 0.05) higher than in a control group, where mothers were matched according to age and parity. After precipitate labour the newborn fared as well as those in the control groups. It is our conclusion therefore, that precipitate labour need not be considered as an intrapartum risk factor, when neonatal well-being is considered.

Adult↗

PubMed1994

Quantification of skeletal alkaline phosphatase in osteoporotic serum by wheat germ agglutinin precipitation, heat inactivation, and a two-site immunoradiometric assay.

Three methods for quantifying skeletal alkaline phosphatase (ALP; EC 3.1.3.1) activity/immunoactivity in serum--heat inactivation, wheat germ agglutinin (WGA) precipitation, and an immunoradiometric assay--were tested for recovery and specificity and applied to 81 sera collected from 14 postmenopausal osteoporotic subjects. The heat-inactivation and WGA precipitation assays showed relative recoveries of 91-100% and 16-32%, respectively, for skeletal ALP with complete specificity (no cross-reactivity with hepatic or intestinal ALP); the IRMA showed a relative recovery of 86-100% and 11-14% cross-reactivity with hepatic ALP. There was a closer correlation between the heat-inactivation assay and IRMA (r = 0.833) than between the WGA precipitation assay and IRMA (r = 0.673) or between the heat-inactivation and WGA-precipitation assays (r = 0.568). The WGA precipitation assay failed to detect skeletal ALP in three serum samples that contained significant amounts as determined by the heat-inactivation assay and the IRMA.

Alkaline Phosphatase↗

PubMed1993

Effect of the chronic dose of diazepam on the intensity and characteristics of the precipitated abstinence syndrome in the dog.

The ability of different chronic doses of diazepam to produce dependence was studied in groups of six dogs who received diazepam p.o. (0.05625, 0.225, 0.5625, 4.5, 9 or 36 mg/kg/day) every 8 hr. After 5 to 6 weeks of stabilization, the intensity of precipitated abstinence was measured by benzodiazepine-precipitated abstinence scores (BPAS) after the p.o. administration of graded doses of the benzodiazepine antagonist, flumazenil (0.66, 2, 6, 18, 36 and 72 mg/kg or a placebo). A modified Latin square design was used. Dogs receiving the two lowest stabilization doses of diazepam showed only liminal signs of precipitated abstinence even with 72 mg/kg of flumazenil. The intensity of the precipitated abstinence syndrome increased with the stabilization dose of diazepam. There was also a dose-related increase in BPAS for increasing doses of flumazenil for all doses of diazepam except the 9-mg/kg/day dose. Not only were quantitative differences observed in precipitated abstinence signs for different levels of diazepam dependence, but the pattern of abstinence signs differed also. Dogs dependent on high doses of diazepam were more sensitive to flumazenil than those dependent on lower doses. Furthermore, seizure activity was seen only in dogs dependent on 9 and 36 mg/kg/day of diazepam. BPAS increased linearly with plasma and brain total and free levels of the sum of diazepam and its metabolites (oxazepam and nordiazepam), but not with free plasma and brain levels of diazepam.

Animals↗

PubMed1996

Construct validation analyses on the Marlatt typology of relapse precipitants.

Marlatt's typology of relapse precipitants has had a major influence on clinical research and practice in the substance use disorders. The purpose of this study was to evaluate the construct validity of the typology, which was done in several ways. First, precipitants of the relapse coded at the baseline assessment and for the first drink post-treatment admission were compared. In addition, baseline relapse precipitants were compared with the highest factor scores recorded in the baseline Inventory of Drinking Situations data. A third set of analyses concerned the relationship among Marlatt precipitant codes, psychiatric diagnoses, and Alcohol Dependence Scale scores. The subjects were 142 men and women who were recruited for this study upon their admission to inpatient or outpatient alcohol treatment programs. Participants completed a baseline assessment covering substance use, including information on the precipitants of a pretreatment "relapse", and other areas of functioning. Subjects then completed bimonthly follow-up assessments during the course of 1 year. The results showed support for only one of the predictions regarding the construct validity of the Marlatt typology. Possible explanations for these findings and their implications for clinical research and practice are discussed.

Adult↗

PubMed1996

Effects of indium and iron ions on in vitro calcium phosphate precipitation and crystallinity.

The elution characteristics of indium and iron ions from six kinds of dental casting alloys were studied in vitro. A certain amount of indium (0.01-1.70 mg/cm2) was solubilized from the surface of only one prosthetic semiprecious brand (Miro Bright) in either 1% lactic acid or 0.05% hydrochloric acid solutions. The elution of iron was below the detection limit or < 0.01 mg/cm2. We also studied the stimulatory effects of indium and ferric ions on the calcium phosphate precipitation in the absence and presence of an inhibitor (phosvitin, a phosphoprotein purified from egg yolks). Indium and ferric ions promoted the reaction, and their stimulatory effects were stronger than the inhibitory effects of phosvitin (250 micrograms/ml). These facts suggest that indium, but not iron, could be eluted into the mouth, and that the eluted indium may stimulate the formation of oral calcium phosphate precipitates, counteracting the inhibition by saliva-derived phosphoproteins. The effects of these metal ions on calcium phosphate precipitates were also studied using both X-ray diffractometry and infrared spectrophotometry. It was shown that both indium and ferric ions decreased the grade of crystallinity of the calcium phosphate precipitates (hydroxyapatite).

Chelating Agents↗

PubMed1980

Accumulation of CPC-precipitable material at apical cell surfaces during formation of the optic cup.

Accumulation of extracellular material at the apical surfaces of cells in the optic vesicle was studied by precipitation with cetylpyridinium chloride (CPC) and scanning electron microscopy. Treatment at low salt concentration to preserve all precipitable material indicated an initial appearance of surface material at the tme that the retinal primordium first formed. The amount of precipitate increased as the optic cup formed, particularly at the margins of the cup. Stability of the precipitate during subsequent washing at higher salt concentrations suggested that the apical cell surface material contained highly acidic glycosaminoglycans. The greatest resistance to extraction occurred during the period in which invagination was most pronounced.

Animals↗

PubMed2003

DNA purification by triple-helix affinity precipitation.

Recent advances in DNA-based medicine (gene therapy, genetic vaccination) have intensified the necessity for pharmaceutical-grade plasmid DNA purification at comparatively large scales. In this contribution triple-helix affinity precipitation is introduced for this purpose. A short, single-stranded oligonucleotide sequence (namely (CTT)(7)), which is capable of recognizing a complementary sequence in the double-stranded target (plasmid) DNA, is linked to a thermoresponsive N-isopropylacrylamide oligomer to form a so-called affinity macroligand (AML). At 4 degrees C, i.e., below its critical solution temperature, the AML binds specifically to the target molecule in solution; by raising the temperature to 40 degrees C, i.e., beyond the critical solution temperature of the AML, the complex can be precipitated quantitatively. After redissolution of the complex at lower temperature, the target DNA can be released by a pH shift to slightly alkaline conditions (pH 9.0). Yields of highly pure (plasmid) DNA were routinely between 70% and 90%. Non-specific co- precipitation of either the target molecule by the non-activated AML precursor or of contaminants by the AML were below 7% and presumably due to physical entrapment of these molecules in the wet precipitate. Ligand efficiencies were at least 1 order of magnitude higher than in triple-helix affinity chromatography.

Affinity Labels↗

PubMed2003

Purification of histidine-tagged single-chain Fv-antibody fragments by metal chelate affinity precipitation using thermoresponsive copolymers.

Metal chelate affinity precipitation (MCAP) has been successfully developed as a simple purification process for proteins that have affinity for metal ions. The present lack of widespread applications for this technique as compared to immobilized metal affinity chromatography (IMAC) may be related to the scarcity of well-characterized metal affinity macroligands (AML) and their applications to the number of different purification systems. In the present work we describe a detailed study of a new purification system using metal-loaded thermoresponsive copolymers as AML. The copolymers of vinylimidazole (VI) with N-isopropylacrylamide (NIPAM) were synthesized by radical polymerization with imidazole contents of 15 and 24 mol%. When loaded with Cu(II) and Ni(II) ions the copolymers selectively precipitated extracellularly expressed histidine-tagged single-chain Fv-antibody fragments (His(6)-scFv fragments) from the fermentation broth free from E. coli cells. Precipitation was induced by salt at mild temperatures and the bound antibody fragments were recovered by dissolving the protein-polymer complex in EDTA buffer and subsequent reprecipitation of the polymer. His(6)-scFv fragments were purified with yields of 91 and 80% and purification folds of 16 and 21 when Cu(II) and Ni(II) copolymers were used, respectively. The protein precipitation capacity of the Ni(II) copolymer showed a dependence on the VI concentration in the copolymer. The SDS-PAGE pattern showed significant purification of the antibody fragments.

Acrylic Resins↗

PubMed1976

The kinetics of protein salting-out: precipitation of yeast enzymes by ammonium sulfate.

Protein solubility can be adequately represented by the classical Cohn equation for the salting-out of alcohol dehydrogenase and fumarase from clarified yeast homogenate with ammonium sulfate. However, the constant beta in this equation is a function of the contacting procedure employed. The kinetics of continuous salting-out were similar for alcohol dehydrogenase and fumarase. The overall rate equation for precipitation had a variable order which was high initially, up to 3.1, but approached unity on completion of precipitation. This was followed by a partial resolution stage which was first order with respect to the concentration driving force. Precipitate particle size was estimated as 0.5 to 5 mum with continuous flow precipitation producing the largest particles.

Alcohol Oxidoreductases↗

PubMed1995

Protein concentration by precipitation with pyrogallol red prior to electrophoresis.

The pyrogallol red protein assay (Clinical Chemistry 1986, 32, 1551-1554) is based upon formation of a blue protein-dye complex in the presence of molybdate under acidic conditions. However, centrifugation of the assay mixture results in loss of color yield and precipitation of the protein-dye complex which can be recovered and resolubilized to achieve protein concentration prior to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The method has been evaluated relative to trichloroacetic acid (TCA) precipitation for recovery and electrophoresis of commercial protein and peptide molecular weight markers. Precipitation with pyrogallol red-molybdate (PRM) gives better and more uniform recovery of both proteins and peptides as compared to TCA. The lower limit of PRM precipitation is similar to TCA and corresponds to 1 microgram protein per mL assay mixture. This is equivalent to 100 microL of 10 micrograms/mL protein using the standard protein assay or 1 microgram/mL protein using a modified assay incorporating a fivefold concentrate of the dye reagent. Application of the method is demonstrated by concentration of urinary proteins. The method is simple and economic and useful for conserving trace amounts of precious sample as it allows recovery of protein for electrophoresis following protein assay.

Chemical Precipitation↗

PubMed1996

Two-dimensional electrophoresis of human urinary proteins following concentration by dye precipitation.

The use of dye precipitation for concentration of proteins prior to 2-DE has been demonstrated by application to human urine. The precipitation methods (T. Marshall and K. M. Williams, Clin. Chem. 1993, 39, 2314-2318; T. Marshall et al., Electrophoresis 1995, 16, 28-31) have been adapted for two-dimensional electrophoresis (2-DE) by modifying the reagent composition and adding sodium dodecyl sulphate (SDS) to the assay mixture. These modifications extend the precipitation range of the methods and overcome the problem of soluble glycoprotein-dye complexes. The protein-dye complex is recovered by centrifugation and dissolved in a small volume of sample denaturing buffer. The dye separates from the protein on 2-DE (forming a sharp band at the anodal end of the isoelectric focusing gel) so that the positional coordinates of the polypeptides are unaffected by the treatment. Dye precipitation provides a simple, rapid and highly economic method for concentrating urines of low to intermediate protein content (0.02-0.50 g/L) prior to 2-DE analysis.

Animals↗

PubMedDate not supplied

Effect of glycoursodeoxycholate on precipitation of calcium carbonate.

The potential role of bile salts in preventing calcium carbonate precipitation was investigated by studying their interaction of Ca2+ and their inhibitory effects on calcium carbonate formation. Glycochenodeoxycholate micelles bound more calcium than did glycocholate. At bile salt concentrations exceeding 12.5 mM, glycoursodeoxycholate bound calcium as well as glycochenodexycholate did. Similar results for calcium binding were observed in mixed micelles of bile salts and lecithin. In bicarbonate (25 or 50 mM) and CaCl2 (10 mM) solutions, calcium carbonate formation was inhibited by the bile salts. Glycoursodeoxycholate and glycochenodeoxycholate (25 mM) prevented calcium carbonate formation which was delayed by glycocholate. This effect is not due to differences between both series of bile salts for calcium binding since glycoursodeoxycholate or glycochenodeoxycholate (25 mM) more efficiently prevented calcium carbonate precipitation than did 35 mM glycocholate in spite of the same Ca2+ binding. These results suggest that some bile salts may have a specific role in preventing calcium precipitation in bile. The mechanism is unknown. The physical properties of glycoursodeoxycholate and glycochenodeoxycholate do not support a role for CaCO3 precipitation in gallstone calcification during litholytic therapy.

Bicarbonates↗

PubMed1978

Identification and behavior of the precipitating BLV antibodies in sera of leukotic cattle.

Precipitating bovine leukemia virus antibodies isolated from bovine leukemic sera by ion-exchange chromatography, gel filtration and affinity chromatography were identified as immunoglobulins of the IgG1 subclass and IgA class. They proved to be different with regard to molecular size and electrical charge. Immunoglobulins IgG2 and IgM as well as low-molecular components ranging in the microglobulin regions (less than 4S) failed to precipitate BLV antigens. Individual bovine leukemic sera showed differing precipitating activities against p24 and gp69 antigens. Precipitating monospecific gp69 antibodies represented exclusively the IgG1 subclass. Some unidentified antigens in disrupted BLV preparations showed serological relationship to p24 and gp69, respectively.

Animals↗

PubMed2003

Structure and properties of the precipitates formed from condensed solutions of the revised simulated body fluid.

Precipitation experiments with aqueous solutions of the Kokubo's revised simulated body fluid (rSBF) equal to 2, 4, 8, and 12 times the ionic concentration of human blood plasma were performed. Instead of Hepes, solution pH was adjusted to the desired value of 7.40 +/- 0.02 by either bubbling of CO2 or addition of HCl. The experiments were performed in tightly closed plastic vessels kept at 37.0 +/- 0.2 degrees C for 72 h under permanent shaking. Afterward, the suspensions were filtrated, and the precipitates were collected and analyzed. The results revealed that increasing the concentration of rSBF resulted in great changes in both the structure and the chemical composition of the precipitates. Phosphate substitution for carbonate (although the amounts of calcium and magnesium remained unchanged) and crystallinity decreasing were the most important modifications found in the precipitates formed from the highly condensed solutions of rSBF.

Apatites↗

PubMed1990

A replica technique for extracting precipitates from zirconium alloys for transmission electron microscopy analysis.

A reliable two-stage carbon replica technique has been developed to extract precipitates from zirconium alloys. Using this technique, all precipitating phases can be extracted from Zircaloy-2, Zr-Cr-Fe, and Zr-Nb-Fe alloys. Precipitate identification using EDS X-ray analysis and convergent beam electron diffraction was greatly facilitated in comparison to thin foils. In addition, the sensitivity for the detection of trace elements in particles was increased using extraction replicas. The chemical compositions of the precipitates as determined from both replica and thin foils were in excellent agreement.

Alloys↗

PubMed1995

Calorimetric determination of the heat of precipitation of pseudoephedrine racemic compound--its agreement with the heat of solution.

The heat of precipitation of dl-pseudoephedrine was determined by direct calorimetry using a Tronac isoperibolic calorimeter. The precipitation of dl-pseudoephedrine was induced by mixing aqueous solutions of the two enantiomers, namely, d- and l-pseudoephedrine, directly in the calorimeter. The molar heat of precipitation of dl-pseudoephedrine was -2.7 and -3.0 kcal/mol at 25 and 30 degrees C, respectively. The aqueous solubility of dl-pseudoephedrine was determined over a temperature range of 20-40 degrees C. The van't Hoff solubility plot was nonlinear. The apparent heat of solution at saturation was obtained from the solubility data using a nonlinear regression model. A good agreement between the magnitude of the apparent heat of solution at saturation and the heat of precipitation was noticed at both 25 and 30 degrees C.

Calorimetry, Differential Scanning↗