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At least 1,639 records · Page 91Linked to original sources
PubMed1982

Centrifugal analysis for serum iron and iron-binding capacity using the IL Multistat III Analyzer.

A colorimetric method for the determination of serum iron and total iron-binding capacity (TIBC) has been adapted to an IL Multistat III Centrifugal Analyzer. The correlation to an ESA Ferrochem, Model 3050, which measures iron by coulometry, is acceptable (IL Multistat = 1.08 ESA--5.05). The intra-run precision gave an average C.V. of less than 5%. The day-to-day precision was between 2% and 7% and the average analytical recovery was 102%. This method requires only 150 microliters of sample for both iron and TIBC which is a significant advantage over many existing methods in terms of sample volume, especially when a pediatric population is considered. Both iron and TIBC may be analyzed at the same time on the same rotor. The approximate analysis time is 30 minutes for seven iron and TIBC samples, four controls and one standard. The cost is low, being approximately $0.08 per iron assay and $0.83 per TIBC assay.

Centrifugation↗
PubMed1983

Rapid turbidimetric determination of serum C3c and C4 by end point centrifugal analysis.

An end point turbidimetric method for the determination of C3c and C4 in serum using a centrifugal analyzer (Cobas Bio) is described. Several analytical factors were evaluated -pH, temperature, PEG and antibody concentration. Wide variations of temperature and pH did not significantly affect the turbidimetric reaction. A 20 g/L PEG concentration and 25-fold antiserum dilution were found satisfactory for the analysis. Precision of the assay was good and comparison with a RID method yielded an r value of 0.97. The procedure is simple and reliable.

Centrifugation↗
PubMed1984

Automated fibronectin assay using light-scattering optics on a centrifugal analyzer.

We describe an automated, kinetic nephelometric method for fibronectin on the Multistat III F/LS Centrifugal Analyzer (Instrumentation Laboratory Inc., Lexington, MA 02173). Antiserum is diluted with polyethylene glycol. Calibrators and samples are prediluted with potassium phosphate buffer (10 mmol/L, pH 7.0) containing 8.5 g of NaCl per litre. Intensity (I) is read at 5 and 180 s and the resulting delta I plotted against concentration. A non-linear least squares curve fitting and interpolation of results is carried out automatically. Three controls, with values of between 190-370 gave coefficients of variation between 4 and 7 percent, and the sensitivity of the method is to 25 mg/L.

Adult↗
PubMed1984

Rapid determination of salicylate in serum on a centrifugal analyzer.

A bichromatic method is described for the determination of salicylate using a micro centrifugal analyzer. Salicylate was quantitated based on its reaction with ferric ion to produce a violet-colored complex. The method provides sample blanking and allows for rapid determination of salicylate levels in serum.

Bilirubin↗
PubMed1984

Comparison of pyridoxal phosphate-supplemented reagent kits for alanine aminotransferase using centrifugal analysis.

The addition of pyridoxal-5-phosphate for assay of alanine aminotransferase has been recommended. The referral methods are inconvenient for high volume instrumentation due to use of multiple reagents and blanks. We adapted a well-documented method to the centrifugal analyzer as a reference for adaptation of two kit methods. Reference intervals obtained and linearity determined were all similar. The kit methods compared favorably to the referral method. Linear regression analysis yielded the following: DOW = 1.011 BERG + 1.666, r = 0.9965; SKI = 0.938 BERG + 4.559, r = 0.9926; and DSKI = 1.028 BERG + 1.051, r = 0.9889. Precision of the assays was acceptable. We concluded that automation of reagent kits incorporating pyridoxal-5-phosphate is feasible and the assays compared favorably to a recommended method. High volume instrumentation can be used without denigration of analytical quality and to allow comparability to a documented method for interlaboratory review.

Adult↗
PubMed1984

Enzymic measurement of primary bile acids and the primary bile acid ratio in serum with the IL-Multistat III Fluorescence Light-Scattering Centrifugal Analyzer.

Enzymic fluorimetric methods are described for the determination of primary bile acids and of chenodeoxycholic acid (CDC) and cholic acid (C) in serum. Bile acids are extracted from 0.3 mL of serum in a simple 5-min step with use of Sep-Pak C cartridges. Total primary bile acids are measured by an equilibrium technique after reaction with beta-NAD in the presence of 7 alpha-hydroxysteroid dehydrogenase. Chenodeoxycholic acid (and its conjugates) is measured by a reaction-rate technique employing the same reaction as above but under different experimental conditions. A small contribution of cholic acid (and its conjugates) to the reaction rate is eliminated by simple calculations. Cholic acid is calculated by difference of the two determinations. In both assays NADH fluorescence is measured with the Multistat centrifugal analyzer. Absolute recovery of bile acids from serum was about 87%. Day-to-day standard deviations for CDC and C were 1.6 and 2.0 mumol/L at serum concentrations of 22.1 and 24.1 mumol/L respectively. Comparison data with a cholylglycine RIA procedure gave the following correlation coefficients (x = RIA, y = proposed method): r = 0.980 (RIA vs total primary bile acids), r = 0.918 (RIA vs CDC) and r = 0.989 (RIA vs C). The methods described appear more practical for use on a routine basis than methods in the literature for the calculation of the primary bile acid ratio.

Adult↗
PubMed1985

Enzymatic measurement of serum glycerol using a COBAS-BIO centrifugal analyzer.

An enzymatic method for the measurement of glycerol using glycerol kinase coupled to pyruvate kinase and lactate dehydrogenase was adapted to a COBAS-BIO centrifugal analyzer. Routine standardization is not required under the optimized conditions since the calculation factor derived from the measurement of pure glycerol standard was found to be identical to the theoretical value. Excellent correlation between the method and the DuPont ACA triglyceride method was obtained. The coefficients of variation for within-run and day-to-day precision were less than 4%. Only 2 microL of serum is required, making this an excellent means for monitoring therapeutic glycerol administration in premature infants with hydrocephalus. The method has the sensitivity to measure glycerol concentrations as low as 0.1 mmol/L. This, together with the rapid analysis time (28 specimens in 10 min), makes it suitable for the correction of glycerol interference in the measurement of serum triglyceride.

Centrifugation↗
PubMed2003

Differences in mitochondrial and nuclear DNA status of high-density and low-density sperm fractions after density centrifugation preparation.

OBJECTIVE: To determine the mitochondrial DNA and nuclear DNA fragmentation of sperm populations separated by using discontinuous density gradient. DESIGN: Analysis of mitochondrial and nuclear DNA status of sperm from high and low density layers. SETTING: Regional fertility center. PATIENT(S): Twenty-eight men who presented for an initial infertility investigation. MAIN OUTCOME MEASURE(S): Semen was prepared by using discontinuous density gradient (90.0%:45.0%) and subjected to a modified long polymerase chain reaction to assess mitochondrial DNA deletions and to a modified single-cell alkaline gel electrophoresis assay to determine nuclear DNA fragmentation. RESULT(S): The high-density fraction displayed significantly more wild-type mitochondrial DNA (75% of samples) than did the low-density fraction (25% of samples). In the high-density fraction, the incidence of single deletions was higher than that of double or multiple deletions, and the deletions were predominantly small. A strong correlation was observed between nuclear DNA fragmentation and the number and size of mitochondrial DNA deletions. CONCLUSION(S): Density centrifugation isolates a population of sperm with high-quality mitochondrial DNA and nuclear DNA.

Adult↗
PubMed1999

Increased recovery of swim-up spermatozoa by application of "antigravitational" centrifugation.

OBJECTIVE: To compare the quantity and quality of sperm recovered following the 10-minute application of an antigravitational force during the swim-up procedure with the standard 60-minute swim-up (SSU) procedure. DESIGN: Prospectively controlled in vitro study. SETTING: Private andrology laboratory and hospital-based infertility practice. INTERVENTION(S): Equal aliquots of semen were evaluated following various intervals of antigravitational centrifugation swim-up (ACSU). ACSU and SSU were then compared. PATIENT(S): Thirty-eight men undergoing therapeutic testing. MAIN OUTCOME MEASURES: Sperm concentration, sperm motility, and progressive sperm motility. RESULTS: The number of sperm recovered from the ACSU procedure was significantly higher than from the SSU procedure. No significant differences in percent motile sperm and progressive motile sperm recovery between the two procedures were observed. CONCLUSION: The ACSU procedure yields a higher number of motile spermatozoa in a much shorter time.

Cell Separation↗
PubMed1988

Cross-axis synchronous flow-through coil planet centrifuge for large-scale preparative counter-current chromatography. I. Apparatus and studies on stationary phase retention in short coils.

Using a new cross-axis synchronous flow-through coil planet centrifuge with a 20-cm revolutional radius, the retention of the stationary phase for nine solvent systems was studied with short coils mounted at two different locations on three holders with 5-, 15- and 25-cm hub diameters. Coils mounted 10 cm to the left of the center of a holder produced a much improved retention of most of the solvent systems compared with the same coils mounted at the center of the holder. In the lateral coil position the retention was found to be affected by the direction of the planetary motion and the head-tail elution mode. This phenomenon may be attributed to the effect of the lateral force field acting asymmetrically between the upper and lower halves of the coil.

Centrifugation↗
PubMed1987

Foam counter-current chromatography with the cross-axis synchronous flow-through coil planet centrifuge.

A novel coil planet centrifuge system performs efficient foam separation in a long multilayer coil. Potential capability of the method was successfully demonstrated in separations of two sets of test samples using sodium dodecyl sulfate as a foaming agent. Rhodamine B with high foam affinity was quickly separated from Evans blue lacking foam affinity. A high concentration of salts such as disodium hydrogenphosphate in the surfactant solution effectively lowered the foam affinity of basic dyes, yielding complete peak resolution of rhodamine B and methylene blue according to a subtle difference in foam affinity.

Centrifugation↗
PubMed2001

Separation of chondroitin sulfate and hyaluronic acid fragments by centrifugal precipitation chromatography.

Centrifugal precipitation chromatography (CPC) was applied for the first time to the separation of fragments of chondroitin sulfate (ChS) and hyaluronic acid (HA). The separation was performed using a gradient elution system between ethanol and water since solubility of these biopolymers highly depends on the concentration of ethanol in aqueous solution. ChS and HA were each eluted into several peaks through a flow-through UV detector at 275 nm, despite they have almost no absorbance at this wavelength in an aqueous solution. The separation was also confirmed by redissolving the dried fraction in water and measuring the absorbance at 210 nm. These results suggest that the CPC system can detect small precipitates of these biopolymers by light scattering at 275 nm. The separated fragments of biopolymers are not easily characterized because no suitable analytical method is available for identification of these compounds. However, the overall results demonstrate that CPC may be a useful separation of biopolymers such as glycosaminoglycans which quantitatively produce precipitates in an organic solvent mixture.

Centrifugation↗
PubMed2002

Centrifugal concentrator for the substitution of nitrogen blow-down micro-concentration in dioxin/polychlorinated biphenyl sample preparation.

A centrifugal concentrator was applied for the substitution of nitrogen blow-down micro-concentration in dioxin/PCB sample preparation. Automation was achieved through this apparatus and resulted in significant improvements in sample preparation productivity, along with excellent reproducibility and recovery rate of dioxin/PCB. Mean recoveries of dioxin congeners were 90-106%, respectively.

Centrifugation↗
PubMed1991

Preparative purification of tetrabromotetrachlorofluorescein and phloxine B by centrifugal counter-current chromatography.

A centrifugal counter-current chromatographic method for preparative purification of commercial tetrabromotetrachlorofluorescein and Phloxine B (D&C Red Nos. 27 and 28, respectively) was developed. Ethyl acetate-n-butanol-0.01 M ammonium acetate (1:1:2) was used as the two-phase solvent system. Each purification trial involved 50 mg of sample and yielded 22 mg (+/- 2 mg) of pure dye. The purity of the product was measured by high-performance liquid and thin-layer chromatography and was found to be 99.9%. The partition coefficients of these compounds were found to be highly concentration-dependent in the two-phase solvent system used. If this problem can be circumvented, then the counter-current chromatographic method can be extended for use with gram quantities of dye.

1-Butanol↗
PubMed1991

Semi-preparative purification of an endogenous ligand for brain serotonin-2 receptors by coil planet centrifuge counter-current chromatography.

A horizontal flow-through coil planet centrifuge equipped with a rotatory frame holding three sets of composite column assemblies was used for purification of an endogenous ligand (ketanserin binding inhibitor) for the [3H]-ketanserin (3H-KET) recognition site. The protein mixture containing the endogenous material was successfully resolved by using a two-phase solvent system consisting of 95% ethanol-31.5% ammonium sulphate (1:2). The active fractions on 3H-KET binding obtained after counter-current chromatography (CCC) were further purified through a C18 microBondapak reversed-phase high-pressure liquid chromatographic column. The introduction of this advanced CCC technique represents an important step in the application of CCC for the separation of polar proteins from protein mixtures.

Ammonium Sulfate↗
PubMed1991

Studies on the preparative capability of the horizontal flow-through coil planet centrifuge and high-performance liquid chromatography in the separation of polar compounds from Oxytropis ochrocephala Bunge.

Horizontal flow-through coil planet centrifuge (CPC) and high-performance liquid chromatography (HPLC) techniques were used for separation of polar compounds from a crude ethanol extract of Oxytropis ochrocephala Bunge, a poisonous legume plant widely distributed in northwestern China. The performance of these two chromatographic methods was compared in terms of column efficiency, peak resolution, separation time, sample loading capacity, etc. The results indicated that two polar compounds in the crude extract were equally well separated by these two methods. HPLC gave comparable peak resolution in shorter separation time while its sample loading capacity was limited to the mg range. The CPC method required a long separation time, but yielded a higher purity of fractions with a much greater capacity.

Centrifugation↗
PubMed2002

Preparative isolation of polyphenolic compounds from Vitis vinifera by centrifugal partition chromatography.

This study deals with a centrifugal partition chromatography developed for the separation of phenolic compounds from Vitis vinifera. EtOAc grape seed extracts were separated using the solvent system hexane-ethyl acetate-ethanol-water (1:8:2:7; v/v) in two fractions: one containing about 75% of flavanol monomers (catechin and epicatechin) corresponding to 18% of crude extract and another fraction B-type dimers (22% of crude extract). From the stalk extracts, we could separate stilbenoid compounds (resveratrol and its oligomers; 12% of crude extract) which were eluted in less than 30 min from flavanols (which required a few hours of additional elution). Using the same solvent system but in different ratios (4:5:3:3; v/v), we isolated the trans-resveratrol (7@1000; 90% purity).

Centrifugation↗
PubMed2003

Protein separation by nonsynchronous coil planet centrifuge with aqueous-aqueous polymer phase systems.

Counter-current chromatographic separation of proteins was performed using a rotary-seal-free nonsynchronous coil planet centrifuge (CPC) fabricated in our laboratory. This apparatus has a unique feature that allows a freely adjustable rotational rate of the coiled separation column at a given revolution speed. The separation was performed using a set of stable proteins including cytochrome c, myoglobin and lysozyme with two different types of aqueous-aqueous polymer phase systems, i.e., PEG (polyethylene glycol) 1000-dibasic potassium phosphate, and PEG 8000-dextran T500 in 5 mM potassium phosphate buffer. Using a set of multilayer coiled columns prepared from 0.8 mm I.D. PTFE tubing with different volumes (11, 24, 39 ml), the effect of the column capacity on the partition efficiency was investigated under a given set of experimental conditions. Among these experiments, the best separation of proteins was attained using the 39 ml capacity column with a 12.5% (w/w) PEG 1000-12.5% (w/w) dibasic potassium phosphate system at 10 rpm of coil rotation under 800 rpm. With lower phase mobile at 0.2 ml/min in the head-to-tail elution, the resolution between cytochrome c and myoglobin was 1.6 and that between myoglobin and lysozyme, 1.9. With upper phase mobile in the head-to-tail elution, the resolution between lysozyme and myoglobin peaks was 1.5. In these two separations, the stationary phase retention was 35.0 and 33.3%, respectively. Further studies were carried out using a pair of eccentric coil assemblies with 0.8 mm I.D. PTFE tubing at a total capacity of 20 ml. A comparable resolution was obtained using both lower and upper phases as a mobile phase in a head-to-tail elution. The results of our studies demonstrate that the nonsynchronous CPC is useful for protein separation with aqueous-aqueous polymer phase systems.

Centrifugation↗