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At least 721 records · Page 40Linked to original sources
PubMed1976

Unusual behaviour of a protein: reversible quantitative precipitation of staphylococcal delta-haemolysin by low concentrations of some organic solvents.

Staphylococcal delta-haemolysin is precipitated from watery solutions by low concentrations of chloroform. The effect on this precipitation of pH, kind and concentration of salts, and concentration of, and time of exposure to, chloroform have been investigated. Some but not all of the other solvents tested cause a similar precipitation. The haemolytic activity is not destroyed and under appropriate conditions precipitation is quantitative. The dry lysin will take up nearly double its weight of chloroform when exposed to the vapour. Some is bound strongly.

Ammonium Sulfate↗
PubMed1986

Calcium carbonate precipitation in bicarbonate hemodialysis.

Calcium carbonate has been observed to precipitate in the fluid pathway of dialysate delivery systems dispensing bicarbonate-containing dialysates. Such precipitation can occlude the fluid pathway, leading to system malfunction and increased maintenance requirements. We show that commercial supplies of sodium bicarbonate are contaminated by trace amounts of sodium carbonate. This contamination may result in immediate precipitation of calcium carbonate on formulation of the dialysate, since bicarbonate-containing dialysates, as formulated, are metastable with respect to calcium carbonate. Sparging of the bicarbonate-containing concentrate with carbon dioxide converts any carbonate to bicarbonate, thus avoiding the formation of precipitates on addition of calcium ions.

Bicarbonates↗
PubMedDate not supplied

Effects of altered temperature and precipitation on desert protozoa associated with biological soil crusts.

Biological soil crusts are diverse assemblages of bacteria, cyanobacteria, algae, fungi, lichens, and mosses that cover much of arid land soils. The objective of this study was to quantify protozoa associated with biological soil crusts and test the response of protozoa to increased temperature and precipitation as is predicted by some global climate models. Protozoa were more abundant when associated with cyanobacteria/lichen crusts than with cyanobacteria crusts alone. Amoebae, flagellates, and ciliates originating from the Colorado Plateau desert (cool desert, primarily winter precipitation) declined 50-, 10-, and 100-fold, respectively, when moved in field mesocosms to the Chihuahuan Desert (hot desert, primarily summer rain). However, this was not observed in protozoa collected from the Chihuahuan Desert and moved to the Sonoran desert (hot desert, also summer rain, but warmer than Chihuahuan Desert). Protozoa in culture began to encyst at 37 degrees C. Cysts survived the upper end of daily temperatures (37-55 degrees C), and could be stimulated to excyst if temperatures were reduced to 15 degrees C or lower. Results from this study suggest that cool desert protozoa are influenced negatively by increased summer precipitation during excessive summer temperatures, and that desert protozoa may be adapted to a specific desert's temperature and precipitation regime.

Animals↗
PubMed1997

Observations on the relationship between gamma-globin chain content and globin chain precipitation in thalassaemic erythroblasts and on the composition of erythroblastic inclusions in HbE/beta-thalassaemia.

Electron microscope immunocytochemical studies were performed on the bone marrow from 2 patients each with beta-thalassaemia major and beta-thalassaemia intermedia and 4 patients with HbE/beta-thalassaemia, using the immunogold technique. Studies of sections that were reacted with mouse monoclonal antibodies against human gamma-globin chains showed the presence of large quantities of gamma-chains in several erythroblasts and marrow reticulocytes containing large amounts of precipitated globin chains. At least in these cells, substantial gamma-chains synthesis did not protect against the formation of erythroblastic inclusions, indicating that factors other than the rate of gamma-chain synthesis influence the extent of globin-chain precipitation. Studies of sections of marrow that were reacted with a rabbit polyclonal antibody against human alpha-globin chains and a mouse monoclonal antibody against human beta-globin chains showed that the erythroblastic inclusions in HbE/beta-thalassaemia did not contain detectable quantities of HbE and consisted only of precipitated alpha-globin chains. Thus, the generally milder phenotype of HbE/beta-thalassaemia cannot be attributed to co-precipitation of HbE and excess free alpha-globin chains.

Antibodies, Monoclonal↗
PubMed1997

Fluoride-induced precipitates on enamel surface and subsurface areas visualised by electron microscopy and confocal laser scanning microscopy.

The present study examined the enamel surface after in vitro topical treatments with a neutral 2% NaF solution. For minimising the risk of artefacts, samples were inspected without pre-treatment as fresh, naturally wet specimens by complementary techniques: variable pressure electron microscopy (VP-SEM) and confocal laser scanning microscopy (CLSM). VP-SEM provided information on the surface morphology, whereas CLSM allowed non-destructive visualisation of subsurface areas. Neutral NaF solutions induced globular precipitates on the enamel surfaces. If the globules formed may be described as "calcium fluoride like material", the additional information of this experiment is that, after interaction with neutral solutions, they also contain considerable amounts of NaF. When the NaF solutions were soaked on pellets and then were brought into contact with the enamel surfaces, NaF crystallites of cubic shape are formed. Confocal optical tomographies of subsurface enamel after treatments with neutral NaF solutions revealed partly coroded enamel structures, whereas VP-SEM showed intact surfaces. In between the coroded areas, a fine granulate precipitate could be observed. This is evidence that fluoride induces the formation of sub-surface precipitates only when applied during demineralisation. The precipitate could be readily removed by 24-h contact with a KOH solution.

Adolescent↗
PubMed1981

Staphylococci producing a non-immune precipitation line with human serum.

When grown on brain heart agar plates, Staphylococcus capitis, S. warneri and S. xylosus produced a precipitation line with normal human serum in the double diffusion test. Eight other staphylococcal species did not produce this line. Of 20 strains of S. capitis, all produced the precipitation line, and the type strain of S. capitis produced the precipitation line against the sera from eight animal species. The precipitation is not caused by protein A and it is not an immune reaction because the serum component is in the albumin fraction of serum when fractionated on Sephadex G-200.

Animals↗
PubMed1984

Interaction of human serum transferrin with Neisseria gonorrhoeae, demonstrated by agglutination and precipitation.

Human sera show non-immune precipitation with ultrasonically disrupted bacteria of the N. gonorrhoeae strain 8551. A human serum was resolved by DEAE cellulose chromatography and immune absorption to isolate the serum component involved in the precipitation. Testing of the final product against antisera to various serum proteins and analysis by SDS-PAGE revealed only serum transferrin. This preparation and transferrin obtained commercially produced precipitation in agar gel against the gonococcal extract. The bacterium was agglutinated by transferrin in solution or when carried by latex particles, and particles sensitized with the bacterial extract were agglutinated by transferrin. Four out of 26 gonococcal strains examined showed reactivity with transferrin in the precipitation and agglutination tests.

Agglutination Tests↗
PubMedDate not supplied

Effects of gas generation and precipitates on performance of Fe0 PRBs.

Long-term reactivity and permeability are critical factors in the performance of granular iron permeable reactive barriers (PRBs). Thus it is a topic of great practical importance, as well as scientific interest. In this study, four types of source solutions (distilled H2O, 10 mg/L TCE, 300 mg/L CaCO3, and 10 mg/L TCE + 300 mg/L CaCO3) were supplied to four columns containing a commercial granular iron material. In all four columns, gases accumulated to approximately 10% of the initial porosity and resulted in declines in permeability of approximately 50% to 80%. In the columns receiving CaCO3, carbonate precipitates accumulated to approximately 7% of the initial porosity, with no apparent decline in permeability. The data indicate that precipitates formed initially at the influent ends of the columns, reducing the reactivity of the iron in this region. As a consequence of the reduced reactivity, calcium and bicarbonate migrated further into the column, to precipitate in a region where the reactivity remained high. Thus precipitation occurred as a moving front through the columns. The results suggest improved methods for PRB design and rehabilitation, and also suggest improvements that are needed in the mathematical models developed for predicting long-term performance.

Calcium Carbonate↗
PubMed1994

Acid precipitation of mammalian cell fermentation broth.

The broth harvested from the "fermentation" of mammalian cells contains many contaminants produced by the cells, including nucleic acids, proteins, and complex polysaccharides, in addition to the product. These contaminants can foul filtration membranes, precipitate during storage or processing steps, and interfere with the performance of chromatographic separations. Acidification of hybridoma cell fermentation broth at the time of harvest from the fermenter has been investigated as a method of selectively precipitating the major contaminants from the soluble antibody product. Between pH values of 6.0 and 4.5, precipitation of the major contaminants is rapid and independent of the temperature (4-37 degrees C), with less than 10% of the antibody coprecipitating in 4 of 5 cases. Antibody activity and physical characteristics were found to be unaltered above a pH of 3.8. Recovery of antibody at the stage of concentrated (50 x), diafiltered bulk was improved from 63% to 84% by using the acid precipitation step. An additional benefit is that retrovirus is effectively inactivated by incubation at a pH below 4.2.

Acids↗
PubMed2003

Physical stability and enthalpy relaxation of drug-hydroxypropyl methylcellulose phthalate solvent change co-precipitates.

The poorly water-soluble drug GWX was co-precipitated with hydroxypropyl methylcellulose phthalate (HPMCP) using a solvent change method. The two co-precipitate formulations made, with drug-HPMCP ratios of 2:8 and 5:5, were analysed using modulated temperature differential scanning calorimetry. They were found to consist of completely amorphous solid solution and a mixture of amorphous solid solution, crystalline drug and amorphous drug, respectively. Stability with respect to crystallization of the two co-precipitates and pure amorphous drug made by quench cooling was compared by storing preparations at 25 degrees C and 40 degrees C, under vacuum over P(2)O(5), and at 75% relative humidity (r.h.). Humidity (75% r.h. compared with dry) had a larger influence on crystallization of the amorphous drug than temperature (25 degrees C compared with 40 degrees C). The solid solution phase in co-precipitates had a relatively higher stability than amorphous drug alone, with respect to crystallization, in presence of the plasticizer water, and crystalline drug. These findings were partly explained by evidence of decreased molecular mobility in the amorphous solid solution with respect to amorphous drug alone, using enthalpy relaxation measurements. At an ageing temperature of 65 degrees C, the calculated half-life for enthalpy relaxation of the 2:8 drug-HPMCP ratio coprecipitate was about 6 orders of magnitude greater than that of amorphous drug alone, indicating a large difference in relative molecular mobility.

Chemical Phenomena↗
PubMed1968

Three IgA myeloma immunoglobulins from the BALB/ mouse: precipitation with pneumococcal C polysaccharide.

Three of 64 IgA immunoglobuilins, derived from plasma cell tumors induced by mineral oil in BALB/c mice, precipitated with species-specific pneumococcus C polysaccharide. A related antigen was also found in group O and some group H streptococci. A difference in ability to precipitate a C polysaccharide from a pneumococcus type XIV was demonstrated between protein 603 which did precipitate and protein 167 which did not precipitate this polysaccharide. Studies of the 167 and 603 proteins showed differences in electrophoretic mobility and polypeptide chains. The antigen-combining site of the 167 and 603 proteins resided on the papain-digestion Fab fragment.

Animals↗
PubMed1982

Protamine precipitation of two reovirus particle types from polluted waters.

Two forms of virus particle are released from reovirus-infected cell cultures, infectious reovirus and potentially infectious reovirus (PIV). PIV particle forms have a complete outer coat and are not infectious until the outer coat is altered or removed. The PIV concentration in polluted waters, however, has not been determined. Protamine sulfate precipitation, using 0.25% fetal bovine serum and 0.005% protamine sulfate for the first precipitation of the sample and 0.0025% for the second, was employed to concentrate infectious reovirus and PIV from water and sewage. Infectious reovirus and PIV particles were concentrated over 500-fold from river water inoculated with virus, and virus recoveries of between 80 and 100% were achieved. Virus precipitates stored at -20 degrees C as a protamine-virus concentrate showed a 5% loss of PIV after 14 days. Virus preparations were assayed, before and after treatment, with 200 micrograms of chymotrypsin per ml, using a fluorescent-antibody procedure. Protamine sulfate precipitation and fluorescent-antibody detection are effective ways to recover and assay reoviruses present in raw sewage.

Chemical Precipitation↗
PubMed1993

Precipitation of cadmium by Clostridium thermoaceticum.

Cadmium at an initial concentration of 1 mM was completely precipitated by cultures of Clostridium thermoaceticum in complex medium. The precipitation was energy dependent and required cysteine, although cysteine alone did not act as a growth substrate. Electron microscopic analysis revealed localized areas of precipitation at the surfaces of nonstarved cells as well as precipitate in the surrounding medium. The addition of cadmium had no apparent effect on growth or acetogenesis. However, nickel and cadmium were synergistically toxic at a concentration (1 mM) at which neither alone was toxic. The amount of protein extracted from cadmium-treated cultures was twofold higher than that in control extracts, and the amount of total sulfide was fourfold higher in cultures containing cadmium than in control cultures. Comparable levels of cysteine desulfhydrase activity were observed in extracts of both cadmium-treated and control cultures, but the enzyme activity was expressed maximally about 24 h earlier in the cadmium-treated cultures than in the untreated controls.

Acetates↗
PubMed2006

Pyridine-2,6-bis(thiocarboxylic acid) produced by Pseudomonas stutzeri KC reduces and precipitates selenium and tellurium oxyanions.

The siderophore of Pseudomonas stutzeri KC, pyridine-2,6-bis(thiocarboxylic acid) (pdtc), is shown to detoxify selenium and tellurium oxyanions in bacterial cultures. A mechanism for pdtc's detoxification of tellurite and selenite is proposed. The mechanism is based upon determination using mass spectrometry and energy-dispersive X-ray spectrometry of the chemical structures of compounds formed during initial reactions of tellurite and selenite with pdtc. Selenite and tellurite are reduced by pdtc or its hydrolysis product H(2)S, forming zero-valent pdtc selenides and pdtc tellurides that precipitate from solution. These insoluble compounds then hydrolyze, releasing nanometer-sized particles of elemental selenium or tellurium. Electron microscopy studies showed both extracellular precipitation and internal deposition of these metalloids by bacterial cells. The precipitates formed with synthetic pdtc were similar to those formed in pdtc-producing cultures of P. stutzeri KC. Culture filtrates of P. stutzeri KC containing pdtc were also active in removing selenite and precipitating elemental selenium and tellurium. The pdtc-producing wild-type strain KC conferred higher tolerance against selenite and tellurite toxicity than a pdtc-negative mutant strain, CTN1. These observations support the hypothesis that pdtc not only functions as a siderophore but also is involved in an initial line of defense against toxicity from various metals and metalloids.

Chemical Precipitation↗
PubMed1996

In vitro precipitation of rat lens crystallins by calpain I--a calpain requiring low amounts of calcium for activation.

The overall goal of this study was to provide data on the function and physiologic significance of lens calpain I, a cysteine protease requiring low amounts of calcium for activation. Reverse-transcriptase polymerase chain reaction was used to detect mRNAs for calpains I and II in young rat lenses. An in vitro model of crystallin precipitation was used to assess the ability of calpain I to induce hydrolysis and precipitation of crystallins. We found that incubation of crystallins with purified calpain I was indeed a powerful inducer of crystallin precipitation. However, mRNA levels for calpain I in whole lens appeared to be lower compared to calpain-II mRNA. Participation of calpain I in crystallin precipitation during normal maturation of rodent lenses or cataract formation is thus theoretically possible, but unlikely, because of the low level of expression of calpain I.

Animals↗
PubMed1984

Study of complement effects on kinetics of immune precipitation.

Influence of complement on the kinetics of immune precipitation was investigated by using simple kinetic tests. In the early phase of immune precipitate (IPPT) formation, it was demonstrated that complement caused inhibition of precipitation only. After formation of a certain critical IPPT mass, alternative pathway-dependent enhancement of precipitation was observed, followed by solubilization of 'enhanced' IPPT and, at last, by solubilization of preformed IPPT. Contrary to inhibition and IPPT solubilization, enhancement of IPPT formation does not change IPPT ability to react with fresh complement.

Animals↗
PubMed2004

Clinical significance of small dense low-density lipoprotein cholesterol levels determined by the simple precipitation method.

OBJECTIVE: Recently, we established a simple method for the quantification of small dense LDL cholesterol (C) using heparin-magnesium precipitation. The small dense LDL-C level was identical to cholesterol in the denser LDL fraction with a density of 1.044 to 1.063 g/mL. The aim of this study was to examine clinical significance of this precipitation method for small dense LDL-C. METHODS AND RESULTS: Small dense LDL-C was measured by a direct homogenous LDL-C assay in the supernatant that remained after heparin-magnesium precipitation with density <1.044 lipoproteins. In 313 normolipidemic subjects, the mean value of small dense LDL-C was 31+/-13 mg/dL. In 462 healthy subjects, small dense LDL-C levels were positively correlated with serum triglyceride and LDL-C and were inversely correlated with high-density lipoprotein cholesterol (HDL-C). Combined hyperlipidemia showed the highest small dense LDL-C level among the various types of hyperlipidemia. Patients with type 2 diabetes had an increased small dense LDL-C level (55+/-17). Patients with coronary heart disease also had increased small dense LDL-C levels (53+/-30) irrespective of the presence of diabetes, whereas their LDL-C levels were comparable to those of normolipidemic controls (111+/-31 versus 104+/-22). CONCLUSIONS: These results suggest that measurement of small dense LDL-C by the present precipitation method is useful to evaluate atherogenic risk and may be applicable to routine clinical examination.

Adult↗