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At least 1,513 records · Page 84Linked to original sources
PubMed1996

[H.E.L.P. therapy (heparin-induced extracorporeal LDL precipitation) in sudden deafness].

BACKGROUND: The H.E.L.P. (Heparin-induced extracorporal low-density lipoprotein precipitation) system selectively eliminates fibrinogen, LDL (low-density lipoprotein) cholesterol, triglycerides, and LP (a) (lipoprotein a) from the blood plasma by means of extracorporal circulation. The reduction of these macromolecules immediately improves the hemorheological situation and leads to a significant decrease of plasma viscosity and red cell transmission time (RCTT), which correlates to the deformation of red blood cells. There are no known contraindications for this therapy. PATIENTS: Sudden hearing loss patients who present to our hospital are admitted for up to ten days. All patients undergo the same standardized imaging studies and examinations, consisting of audiological tests, X-rays and CT of the base of the skull, X-rays of the cervical vertebral column, neurological and internal examination, blood tests, and CSF aspiration. Patients with no obvious etiology for their hearing loss and no improvement of their hearing after two weeks of treatment with intravenous vasodilators and corticosteroids were referred for the H.E.L.P. protocol. RESULTS: We report on five patients with idiopathic sudden hearing loss who following the H.E.L.P. protocol showed complete remission or evident improvement of hearing after H.E.L.P. therapy. CONCLUSIONS: Heparin-induced extracorporal LDL (low-density lipoprotein) precipitation (H.E.L.P.) improves the blood flow and the microcirculation and therefore could be a new and effective method for the treatment of sudden hearing loss.

Audiometry, Pure-Tone↗
PubMed2002

A modified dot-blot method of protein determination applied in the tannin-protein precipitation assay to facilitate the evaluation of tannin activity in animal feeds.

Tannins have received considerable attention from animal nutritionists as potential agents for modifying ruminal fermentation patterns, or for exploring new feed resources. This group of secondary plant compounds is defined by their ability to form complexes with proteins. A widely accepted method for assaying the biological activity of extracted tannins is the precipitation of bovine serum albumin. The protein carries a radioactive label (125I) to allow direct quantification from the precipitate. Tannin-protein complexes dissolve in sodium dodecylsulfate solution. A dot-blot assay for protein determination, which is based on the reversible binding of a fluorochrome, benzoxanthene yellow, to the protein spots and is not disturbed by the presence of detergents, can replace the radioactive method by a fluorimetric measurement. A novel alternative to the last part of the dot-blot assay is to scan the stained protein spots in situ using a video camera and computer image analysis. Several filter sets were tested and, within a concentration range of 0.1-2.0 mg protein/ml, each of them yielded results identical to the original method while the time required was only 30 % of the working time consumed by the original procedure. The modified dot-blot assay should be applicable to the evaluation of tannin activity in all shrub and tree foliages considered as animal feed.

Animal Feed↗
PubMed1986

Extraction and quantitative precipitation of nuclear ribonucleoprotein particles.

Ribonucleoprotein particles (RNPs) were extracted from monkey cell nuclei in media of low ionic strength. The rapidly labeled RNPs were comparable in terms of size, protein patterns and protein content to those extracted by sonication. The overnight labeled RNPs were homogenous (sedimenting at 60-65S and containing RNA of 30-31S), and appear to be a subset of pre-ribosomal RNPs. This procedure produces nuclear RNPs free of contaminating chromatin. Nuclear RNPs (rapidly-labeled and overnight-labeled RNPs, extracted by either our procedure or by sonication), quantitatively precipitated in 10 mM MgCl2 when the concentration of monovalent cations was low. There was no detectable degradation of the RNA components, nor was there loss of enzymatic activity of an RNP associated protein kinase. Precipitation in Mg++ provides a rapid, gentle and convenient method of concentrating RNPs.

Animals↗
PubMed1993

Enzyme immunoassay based survey of precipitation and surface water for the presence of atrazine, metolachlor and 2,4-D.

The suitability of enzyme immunoassay (EIA) as a method of analysis for 2,4-D, atrazine and metolachlor contamination in water samples was determined by comparing EIA results to gas chromatography (GC) results. The comparison of EIA and GC results yielded a correlation coefficient of 0.92, 0.98 and 0.92 for 2,4-D, atrazine and metolachlor, respectively. EIA was used to monitor seasonal trends in the concentrations of 2,4-D, atrazine and metolachlor in surface water and precipitation throughout the province of Ontario, Canada. 2,4-D was detected in excess of 4 micrograms/L in urban creeks during the period of application. Concentrations of 43 and 9 micrograms/L of atrazine and metolachlor, respectively, were detected during the field application period in surface water samples from the Kintore Creek watershed. The levels of 2,4-D, atrazine and metolachlor detected exceeded the Canadian Water Quality Guidelines for the protection of fresh water aquatic life. Concentrations as high as 445 and 322 ng/L of atrazine and metolachlor, respectively, were detected in precipitation samples collected from 17 locations in Ontario during the herbicide application period. The EIA was shown to be qualitatively and quantitatively comparable to GC analysis.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2006

Preparation of All-Trans Retinoic Acid nanosuspensions using a modified precipitation method.

All-Trans Retinoic Acid (ATRA) nanosuspensions were prepared with a modified precipitation method. The ATRA solution in acetone was injected into pure water by an air compressor under the action of ultrasonication. Photon correlation spectroscopy results showed that the mean particle size of ATRA nanoparticles in nanosuspensions reduced from 337 nm to 155 nm as the injection velocity increased and the polydispersity index was 0.45-0.50. The morphology of ATRA nanoparticles varied with the different concentration of ATRA solution in acetone. ATRA nanoparticles showed an amorphous state and stable in 6 months. It could be concluded that this modified precipitation method could produce stable and controllable ATRA nanosuspension to a certain extent, thus benefit for higher saturation solubility.

Acetone↗
PubMed2005

[Experimental validation of calcium phosphate precipitation modeling in a pellet reactor].

Calcium phosphate precipitation is studied in this article. The P-recovery process is carried out in a fluidized sand bed, the so-called pellet reactor which presents major advantages from the hydrodynamical viewpoint. The associated chemistry is yet relatively complex, due to pH gradient along the column and to the residence time of the various precipitates. The experimental observations showed three different phenomena: first, an agglomeration of fines around the sand grains is observed, second, a stagnation of fines in the bed occurs while a significant amount of fines also leaves the bed with the liquid effluent. The purpose of this work is to validate the thermodynamical model developed in our previous works on a semi-industrial sized pilot. Additional experimental runs carried out for various operating conditions showed the robustness of the model. These results open some interesting perspectives for the determination of optimized operating conditions at industrial scale.

Calcium Phosphates↗
PubMed2001

Rem nut ion exchange plus struvite precipitation process.

Nutrients control technologies from wastewater are based on destructive technologies which defer the problem fromthe diluted liquid-phase (effluent) to a more concentrated waste (sludge) in the case of phosphates, or to nitrogen gas and/or volatile compounds in the case of ammonia. The REM NUT process allows for simultaneous removal of phosphate and ammonium ions by selective ion exchange and recovery by chemical precipitation in the form of struvite (magnesium ammonium phosphate) from the spent exchangers regeneration eluates. In the paper revised versions of the REM NUT process, i.e., P-driven layouts, are presented and cost effectiveness is compared to chemical precipitation based on the use of ferric chloride.

Chemical Precipitation↗
PubMed2005

The isolation of soyasaponins by fractional precipitation, solid phase extraction, and low pressure liquid chromatography.

Bioactive soyasaponins are present in soybean (Glycine max). In this study, the isolation of soyasaponins in relatively pure form (>80%) using precipitation, solid phase extraction and reverse phase low pressure liquid chromatography (RP-LPLC) is described. Soy flour soyasaponins were separated from non-saponins by methanol extraction and precipitation with ammonium sulphate. Acetylated group A soyasaponins were isolated first by solid phase extraction followed by RP-LPLC (solvent: ethanol-water). Soyasaponins, from a commercial preparation, were saponified and fractionated into deacetylated group A and group B soyasaponins by solid phase extraction (methanol-water). Partial hydrolysis of group B soyasaponins produced a mixture of soyasaponin III and soyasapogenol B monoglucuronide. RP-LPLC of deacetylated group A soyasaponins separated soyasaponin A1 and A2 (38% methanol); of group B soyasaponins isolated soyasaponin I (50% ethanol); and of the partial hydrolysate separated soyasaponin III from soyasapogenol B monoglucuronide (50% ethanol). This methodology provides soyasaponin fractions that are suitable for biological evaluation.

Chromatography, Liquid↗
PubMed2004

Comparison of three homogeneous methods for measuring high-density lipoprotein cholesterol with a precipitation method in diabetic and non-diabetic subjects.

Three homogenous methods for the automated measurement of high-density lipoprotein-cholesterol (HDL-C) are studied and compared with a precipitation method in diabetic and non-diabetic subjects. All three methods meet the precision criteria of the National Cholesterol Education Programme (NCEP). Triglycerides did not cause significant interference up to 10 mmol/L in the immuno-inhibition method (Wako) and up to 40 mmol/L in the Randox and Roche methods. Haemoglobin, up to a concentration of 5 g/L, had only negligible effect on the performance of all three homogeneous methods. Bilirubin caused an increasing positive bias in all methods above a concentration of 50 micromol/L. In comparison with the precipitation method, the new homogeneous methods agreed for type 1 diabetic patients but showed a positive bias for the control subjects and patients with type 2 diabetes. The bias of HDL-C levels in type 2 diabetes may be sufficient to affect the calculation of cardiovascular risk, and may therefore influence the decision to prescribe lipid-lowering medication.

Bilirubin↗
PubMed2002

Electrostatic precipitation of ultrafine particles enhanced by simultaneous diffusional deposition on wire screens.

A laboratory-scale electrostatic precipitator has been designed and constructed in which the grounded collector plate has been substituted by a set of wire screens placed perpendicularly to the gas flow. Particles are deposited onto the screens by two mechanisms--electrostatic deposition and diffusional deposition--which act simultaneously. On the one hand, electrostatic deposition is effective for relatively large particles, but it is quite ineffective for the smallest ones because their charging probability in the corona field is too low. On the other hand, the diffusional collection efficiency of particles on fibers is high for small particles but low for the larger ones. Therefore, the simultaneous diffusional-electrostatic precipitation may become a useful technique for efficient filtration of particles below 0.1 microm. A preliminary experimental evaluation of this filtering device has shown that submicrometer particles with diameters down to a few nanometers can be collected with number efficiencies greater than 99%.

Air Pollutants↗
PubMed2003

Dissolution and absorption modeling: model expansion to simulate the effects of precipitation, water absorption, longitudinally changing intestinal permeability, and controlled release on drug absorption.

A previously described model for simulating drug dissolution, absorption, and pharmacokinetics has been expanded beyond the original application of simulating immediate-release dosage forms to include simulation of drug precipitation, water absorption from the gastrointestinal tract, changing gastrointestinal permeability, disintegration, and controlled-release and dissolution from a GITS-type dosage form. A mathematical description of the model is presented as well as a retrospective analysis of nifedipine to demonstrate the utility of the model. The fourth-order Runge-Kutta numerical method was used to solve the series of coupled differential equations used to simulate the process of dissolution, absorption, and drug disposition. The model was able to simulate the clinically demonstrated effect for drug particle size on nifedipine plasma concentrations for an immediate-release dosage form. Further simulations indicated that drug particle size was less important for a GITS-type dosage form at a release rate of 1.7 mg/hr compared to rate of 17 mg/hr. Hypothetical calculations simulated the potential effect of drug precipitation, water absorption, and changing permeability on drug plasma concentrations. The expanded model increases the utility of a previously described model in providing guidance in drug development and selection.

Biological Availability↗
PubMed2004

A study on dissolution properties of the sludges from Cr(VI) reduction-precipitation processes.

In this article, dissolution characteristics of Cr(VI) reduction-precipitation sludges in the solutions containing mineral acids, organic complexing materials or both are examined. For this purpose, the effects of pH, concentration of complex forming agent and contact time on dissolution of metals from two different sludges obtained by using sodium sulphite and ferrous sulphate as reducing agents are studied. In addition, pollution potentials of the sludges are determined by applying the toxicity tests of TCLP, SPLP, USEPA-1979, and USEPA-19X0. It was found that pH, contact time, concentration and type of complex forming substances are effective parameters on dissolution of metals from the sludges. In mineral acid solutions at pH 3, especially in the presence of organic complexing substances, chromium leached out from hydroxide sludges exceeds the concentration limits of USEPA for hazardous wastes. The amounts of chromium dissolved in the citric and ascorbic acid solutions and the amount of iron dissolved in the EDTA solution were found to be higher than in the other test solutions. Also, TCLP test shows that chromium hydroxide sludge obtained from sulphite reduction precipitation process of Cr(VI) is a potential hazardous solid. According to the results of this study, considering the probable presence of complexing agents in the disposal sites, toxicity test methods should be modified.

Carcinogens, Environmental↗
PubMed1999

Inhibition of human immunodeficiency virus type 1 replication by the K10-K42 peptide of GAP31 is due to induction of rapid but nonspecific precipitation of viral and nonviral proteins.

The 33-amino acid peptide K10-K42 has previously been described as having potent anti-HIV-1 activity, and antiviral efficacy against hepatitis B and human cytomegalovirus in vitro. Although the exact mechanism of antiviral activity was unknown, it was hypothesised that the K10-K42 peptide inhibited HIV-1 by interfering with one or more of the intracellular processes of reverse transcription, integration, and/or viral gene expression. We performed a series of experiments to identify and characterize the inhibitory mechanism, and to determine whether intracellular expression of the K10-K42 peptide would potentiate its antiviral efficacy in vitro. Surprisingly, our results revealed that the antiviral activity of the K10-K42 peptide could be explained without implicating intracellular inhibition of HIV-1 replication. The activity appeared to be due to an extraordinary capacity of the K10-K42 peptide to precipitate viral and nonviral proteins in vitro. The protein-precipitating capacity of the K10-K42 peptide was sequence specific and a scrambled version of the 33-amino acid peptide did not retain the activity. Although the unusual biochemical properties of the K10-K42 peptide probably negate a number of potential therapeutic applications, they do merit further investigation. Moreover, these findings provide a plausible explanation of the mechanism by which the K10-K42 peptide can inhibit replication of viruses from families as genetically and functionally diverse as Retroviridae, Hepadnaviridae, and Herpesviridae.

Amino Acid Sequence↗
PubMed1995

Determination of propofol in blood by HPLC. Comparison of the extraction and precipitation methods.

The use of intravenous agents to maintain anesthesia has become increasingly popular since the introduction of propofol. Its popularity results from the fact that in 95% of patients given 2.5 mg propofol per kilogram of body weight, the induction of the drug is rapid and smooth and is followed by rapid recovery with a low incidence of postoperative side effects. In order to study the physiological effects of an intravenous anesthetic agent, it may be necessary to determine its concentration in blood. This paper deals with the high-performance liquid chromatographic analysis of propofol in blood. The concentration values are calculated from the application of extraction and precipitation procedures. Observed differences resulting from the two analytical methods are discussed and interpreted with reference to investigations of blood, plasma, and water solutions of propofol and the precipitation of solid elements in blood.

Chemical Precipitation↗
PubMed1999

Compatibility and stability of aplidine, a novel marine-derived depsipeptide antitumor agent, in infusion devices, and its hemolytic and precipitation potential upon i.v. administration.

Aplidine is a novel marine-derived antitumor agent isolated from the Mediterranean tunicate Aplidium albicans. The compound is pharmaceutically formulated as a lyophilized product containing 500 microg active substance per dosage unit. Prior to i.v. administration it is reconstituted with a solution composed of Cremophor EL, ethanol absolute and Water for Injection (15/15/70% v/v/v) with further dilution in 0.9% w/v sodium chloride for infusion (normal saline). The aim of this study was to investigate the compatibility of aplidine infusion solutions with polyvinyl chloride (PVC)-containing and PVC-free administration sets, and to determine the stability of aplidine after reconstitution and further dilution in infusion solutions. Furthermore, in vitro biocompatibility studies to estimate the hemolytic and precipitation potential of aplidine infusion solutions upon i.v. administration were conducted. In this study we show that sorption of aplidine to PVC and to a lesser extent to PVC-free administration set materials occurs. Also, most probably due to the presence of Cremophor EL in the infusion solution, significant leaching of diethylhexyl phtalate (DEHP) from the PVC administration set occurs. After reconstitution and dilution the drug is stable for at least 24 and 48 h, respectively, in glass containers when stored at room temperature (20-25 degrees C) and ambient light conditions. We found that aplidine should be administered in infusion concentrations equal or above 28.8 microg/ml using a PVC-free administration set consisting of a glass container and PVC-free infusion tubing. After reconstitution it must be diluted further with normal saline within 24 h after preparation and subsequently administered to the patient within 48 h. Additionally, results from the biocompatibility studies show that neither hemolysis nor precipitation of aplidine is expected upon i.v. administration.

Antineoplastic Agents↗
PubMed1984

An electrostatic precipitator for the study of airborne radioactivity.

An system has been developed to measure airborne radioactivity using electrostatic precipitation for collection and alpha-particle spectroscopy for detection. Features include good energy resolution (e.g. 170 and 300 KeV for full-width half maximum and full-width tenth maximum for 7.7-MeV alpha particles using a 7-cm2 area detector; and 52- and 122-KeV, respectively, using 1.2-cm2 area detector) and versatile computer control for collection, counting and data reduction. Aerosols bearing the radioactive atoms are deposited on a foil tape by electrostatic precipitation for a predetermined time after which the foil is moved under a solid-state detector to count the alpha-particle emissions. Activities are determined at the same frequency as samples are collected. Helium gas can be introduced at the detector to reduce energy loss and improve resolution. Although in principle certain aerosol sizes could be difficult to collect, in practice no difficulties were observed for typical environmental conditions, provided sufficiently low air-sampling rates were used. One important application is the measurement of 222Rn daughters. The sensitivity is such that detection of individual daughter concentrations less than 0.1 pCi/l. with only a 10% counting error is possible.

Air Pollution, Radioactive↗
PubMed1986

The influence of an electrostatic precipitator and a mechanical filter on Rn decay products.

In the present work the effect of an HEPA filter and an electrostatic precipitator on the behaviour of Rn decay products has been studied in laboratory conditions. Both filters were found to decrease the equilibrium factor of progeny and increase the unattached fraction of decay products. In a clean air they also decreased the activity of unattached progeny. An electrostatic precipitator was found to produce condensation nuclei which were observable when no other particle sources were present. The ozone produced by the corona discharge of the filter probably has a great effect on the production of these submicron particles. The impurities of the air were found to grow the particles and thus their influence on the behaviour of Rn decay products became in some cases significant.

Air Pollution, Radioactive↗
PubMed2003

Results of surveys at United States pulp and paper mills for the presence of scales and precipitates containing naturally occurring radioactive material (NORM).

Field surveys were carried out at sixteen pulp and paper mills in the United States--seven kraft process, two sulfite process, and seven recycling process mills--for the presence of naturally occurring radioactive material (NORM) in precipitates and scales. NORM was detected at three of the kraft mills, one sulfite mill, and none of the recycling mills. At one of the kraft mills, the NORM was associated with a commercial aluminum sulfate ("alum") slurry used on the paper machines and in intake water treatment. The maximum activity level of this alum scale was 252,000 Bq kg(-1) (6,800 pCi g(-1)) 228Ra. At two kraft mills, NORM was associated with precipitates in the bleach plant. The measured NORM activity in samples of these scales was approximately 44,400 Bq kg(-1) (1,200 pCi g(-1)) 226Ra. Where NORM was detected at a sulfite mill, the NORM deposits were found adhering tightly to the surfaces of brownstock washers. Although samples were not removed for radionuclide analysis, survey readings at the drum surface were 26 nC kg(-1) h(-1) (100 microR h(-1)) with a scintillation counter and 2,200 cpm with a Geiger-Muller counter. At all mills, exposure rate measurements and risk assessment calculations indicated that it would be highly unlikely for any worker's annual exposure to exceed 1 mSv (100 mrem) (the Nuclear Regulatory Commission limit for untrained workers) due to exposure to these materials.

Background Radiation↗