SEARCH · PubMed Health

Results for “performance”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources

PubMed1987

Performance of disabled and normal readers on the Continuous Performance Test.

Twelve-year-old reading-disabled children of normal intelligence were compared on the Continuous Performance Test with two control groups of normal intelligence and reading ability either of the same age or of the same reading age as the reading-disabled group. Signal-detection analysis showed that the reading-disabled were more conservative than chronological-age controls in their willingness to identify the target letter sequence. Although this conservative performance was shared by the reading-age controls, the reading-disabled suffered an additional handicap of relatively frequent anticipatory errors. Groups also differed on a sensitivity measure, suggesting a deficit in working memory in the reading-disabled children.

Attention↗

PubMed1993

Analysis of carbohydrates in glycoproteins by high-performance liquid chromatography and high-performance capillary electrophoresis.

We describe two methods for the analysis of oligosaccharide chains in glycoproteins by high-performance liquid chromatography (HPLC) and high-performance capillary electrophoresis (HPCE). O- and N-glycosidically linked oligosaccharides released from glycoproteins can be identified as their borohydride-reduced forms by anion-exchange HPLC with pulsed amperometric detection. N-Glycosidically linked oligosaccharides can also be analyzed as 2-aminopyridine derivatives by HPCE in direct zone electrophoresis mode in an acidic phosphate buffer and zone electrophoresis mode as borate complexes in an alkaline buffer. We also present a convenient procedure for the analysis of the constituent monosaccharides of these oligosaccharides chains by HPLC based on reversed-phase partition mode as 1-phenyl-3-methyl-5-pyrazolone derivatives.

Aminopyridines↗

PubMedDate not supplied

Myocardial performance index combining systolic and diastolic myocardial performance in doxorubicin-treated patients and its correlation to conventional echo/Doppler indices.

This study was designed to evaluate the utility of myocardial performance index (MPI) in anthracycline cardiotoxicity. The MPI measures the ratio of total time spent in isovolumic activity (isovolumetric contraction time and isovolumetric relaxation time) to the ejection time, thus giving a global index combining systolic and diastolic myocardial performance. In this study, MPI was measured in 35 doxorubicin-treated children (aged 108.5+/-55.31 months, 23 males and 12 females) in sinus rhythm and 32 age-matched controls, and it was compared with conventional Doppler echocardiographic parameters. The isovolumetric contraction time was prolonged (38.37+/-24.43 vs 26.37+/-15.53, p <0.02) and ejection time was shortened (231.91 +/- 28.87 vs 256.21+/-19.55, p<0.001) in doxorubicin-treated patients compared to that in normal children. The isovolumetric relaxation time did not show significant difference between patients and control group (60.11+/-10.92 vs 61.06+/-12.12, p>0.05). MPI was significantly increased in doxorubicin-treated patients compared with that in control groups (0.42+/-0.07 vs 0.34+/-0.06, p<0.001), and significant correlation was observed between MPI and fractional shortening, ejection fraction, and left ventricular end diastolic and end systolic diameters (respectively, r = -0.508, p <0.002; r = -0.532, p<0.001; r = 0.467 p<0.005; r=0.606, p<0.001). Also, a weak correlation was found between MPI and duration of the disease and patient ages (r = 0.393, p < 0.02; r = 0.379; p < 0.02). However, there was no correlation between MPI and cumulative doxorubicin dose (r = 0.311, p > 0.05) and diastolic Doppler parameters in doxorubicin-treated patients. We think that MPI may be a useful parameter in monitoring left ventricular dysfunction in anthracyline-treated patients.

Antineoplastic Agents↗

PubMed1989

Safety and efficacy of percutaneous transluminal coronary angioplasty performed at time of diagnostic catheterization compared with that performed at other times.

Performing diagnostic cardiac catheterization and percutaneous transluminal coronary angioplasty (PTCA) as a single, combined procedure might provide savings in patient hospitalization days and more efficient use of catheterization laboratory time. To assess the safety and efficacy of combined diagnostic coronary angiography and PTCA, we reviewed all elective PTCA procedures performed at our institution during 1985 and 1986 so that we could compare patients who had diagnostic angiography and angioplasty on separate days (n = 404) with those who had the combined procedure (n = 120). The success rate and incidences of urgent bypass surgery, acute myocardial infarction, transient azotemia and procedure-related death were not different in the 2 groups. The mean hospitalization time was 6.2 days in the group with combined angiography and angioplasty, and 7.3 days in the group having separate procedures.

Angiography↗

PubMed1992

A review and reappraisal of electronic performance monitoring, performance standards and stress allowances.

There is a growing trend toward electronic performance monitoring (EPM) to track the performance of workers engaged in computer-based tasks. Despite the possible productivity advantages of this approach to work management, the use of EPM may produce stress through work overload, negative computer feedback, loss of incentive pay and threat of job loss. These stress effects are most likely to occur among workers who have difficulty meeting work standards (eg, forms processed per hour) enforced through EPM. A stress allowance is proposed as a new category of work allowance for adjusting EPM work standards so as to minimize imbalances between task demands and the worker's resources to adapt.

Journal Article↗

PubMed1994

Recombinant human insulin. III. High-performance liquid chromatography and high-performance capillary electrophoresis control in the analysis of step-by-step production of recombinant human insulin.

The production of recombinant human insulin consists of five main stages, accompanied by considerable transformation of molecules, concerning size, secondary structure and the presence of charged groups. The application of different methods, i.e., size-exclusion, ion-exchange and reversed-phase high-performance liquid chromatography (HPLC) and high-performance capillary electrophoresis (HPCE) (capillary zone electrophoresis and micellar electrokinetic capillary chromatography), to the analysis of insulin, insulin-related and non-insulin-related substances was studied. A combined HPLC-HPCE system for the step-by-step control of recombinant human insulin production technology is suggested. The advantages and shortcomings of these methods are discussed.

Amino Acid Sequence↗

PubMed1996

Fractals for multicyclic synthesis conditions of biopolymers. Examples of oligonucleotide synthesis measured by high-performance capillary electrophoresis and ion-exchange high-performance liquid chromatography.

We have developed models of patterns for nucleotide chain growth. These patterns are measurable by high-performance capillary electrophoresis and ion-exchange high-performance liquid chromatography in crude products of solid-phase synthesized 30mer and 65mer oligodeoxyribonucleotide target sequences N. We introduce mathematical methods for finding characteristic values d(o) and p(o) for constant chemical modes of growth as well as d and p for non-constant chemical modes of growth (d = probability of propagation, p = probability of termination). These methods are employed by presenting the accompanying computer software developed by us in C code, Mathematica R languages, and Fortran. Characteristic values of the parameters d, p, and the target nucleotide length N describe the complete composition of the crude product. From this we have developed the relation 2 - [N/(N - 1)]/Da, measurable(N,d) as a universal quantitative measure for multicyclic synthesis conditions (D, fractal dimension and similarity exponent, respectively). We use this mathematical treatment to compare the efficiency of oligodeoxyribonucleotide syntheses of different target length N on polymer support materials. Further, we analyze selected syntheses of short and long oligodeoxyribonucleotides as well as single-stranded DNA sequences by well-known empirical autocorrelation, fast Fourier transformation, and embedding dimension techniques.

Base Sequence↗

PubMed1992

Comparison of high-performance liquid chromatography and high-performance capillary electrophoresis for the determination of cicletanine in plasma.

A sensitive and selective high-performance capillary electrophoresis (HPCE) procedure was developed for the determination of total cicletanine in human plasma. The procedure consisted in extraction of the drug with diethyl ether and analysis by micellar electrokinetic capillary chromatography in a fused-silica capillary using sodium dodecyl sulphate in the run buffers and ultraviolet detection. The concentrations of cicletanine obtained by this method were compared with those obtained by a high-performance liquid chromatographic (HPLC) method used routinely. The within-run precision of the methods, expressed as relative standard deviation, ranged from 1.6 to 7.8% for HPLC and from 6.4 to 11.1% for HPCE. Both methods showed an adequate level of accuracy; the relative errors ranged from 0.02 to 3.25% for HPLC and from 0.21 to 2.90% for HPCE. The HPCE method required less than half the time taken by the HPLC method, making HPCE a useful alternative technique for the routine determination of cicletanine in plasma. Both methods were used to follow the time course of total cicletanine in human plasma after a single oral therapeutic dose of the drug.

Antihypertensive Agents↗

PubMed1993

Determination of nicotine and two major metabolites in serum by solid-phase extraction and high-performance liquid chromatography, and high-performance liquid chromatography-particle beam mass spectrometry.

A rapid and selective assay of nicotine, cotinine and trans-3'-hydroxycotinine in human serum, based on high-performance liquid chromatography with UV detection has been developed. The compounds were subjected to solid-phase extraction, using Extrelut 1 cartridges. Recoveries were ca. 95% for nicotine, 90% for cotinine and 50-55% for trans-3'-hydroxycotinine. The limit of quantitation observed with this method was 10 ng/ml for nicotine and 5 ng/ml for each of the metabolites. The compounds were also identified using high-performance liquid chromatography with particle beam mass spectrometry, to confirm their presence in human serum.

Chromatography, High Pressure Liquid↗

PubMed1995

Evaluation of high-performance liquid chromatography for the separation and determination of arsenic species by on-line high-performance liquid chromatographic-hydride generation-atomic absorption spectrometry.

An on-line high-performance liquid chromatographic-microwave assisted oxidation-hydride generation-atomic absorption spectrometric (HG-AAS) system (using columns of different kinds) has been developed for the determination of arsenite, arsenate, dimethylarsinate (DMA), monomethylarsonate (MMA), arsenobetaine (AsB) and arsenocholine (AsC) in environmental samples. Ion-pair reversed-phase chromatography using tetrabutylammonium phosphate as the ion-pair reagent and anion-exchange chromatography were evaluated and the analytical performances of each are reported. The detection limits were 97-143 and 10-30 micrograms l-1 for ion-pair reversed-phase and anion-exchange chromatography, respectively. The Hamilton PRP-X 100 anionic column was proposed for the determination of the six species; AsB can be quantitated independently of AsC by taking the difference between readings at pH 6 and pH 10.7. The proposed methods were applied to water samples and sediments and their potential for future application was demonstrated.

Arsenicals↗

PubMed2004

Effect of high-temperature on high-performance liquid chromatography column stability and performance under temperature-programmed conditions.

Six commercially available analytical (4.1 or 4.6 mm i.d.) columns were evaluated under temperature-programmed high-temperature liquid chromatography (HTLC) conditions to access their stability and performance at extreme temperatures. Seven components consisting of acidic, basic and neutral compounds were analyzed under temperature-programmed conditions and solvent gradient conditions using three different mobile phase compositions (acidic, basic and neutral). Each column was checked with a two-component test mix at various stages of the evaluation to look for signs of stationary phase collapse. Three zirconia based stationary phases studied exhibited column bleed under temperature-programmed conditions. The other three columns, a polydentate silica column, a polystyrene-divinylbenzene (PS-DVB) polymeric column, and a graphitic carbon column performed well with no evidence of stationary phase degradation. The R.S.D. for the retention times and efficiencies were less than 10% for most conditions, and not more than 15% during the course of the evaluation for each column. The polydentate silica stationary phase was temperature programmed to 100 degrees C, the PS-DVB stationary phase was temperature programmed up to 150 degrees C, and the graphitic carbon column was used with temperature programming up to 200 degrees C. Comparable peak capacities and similar retention behaviors were observed under solvent gradient and temperature-programmed conditions. Temperature programming with dynamic mobile phase preheating can replace solvent gradient analysis without a loss of peak capacity when used with 4.1 or 4.6 mm columns.

Chromatography, High Pressure Liquid↗

PubMed2006

Comparison of ultra-performance liquid chromatography and high-performance liquid chromatography for the determination of priority pesticides in baby foods by tandem quadrupole mass spectrometry.

Determination of 16 priority pesticides and transformation products specified in the EU Baby Food Directive 2003/13/EC has been compared using high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC) coupled to tandem quadrupole mass spectrometry (MS/MS). Prior to analysis, co-extractives were removed from acetonitrile extracts using dispersive solid-phase extraction (SPE) with primary secondary amine (50 mg). Extracts spiked with pesticides at 1 microg kg(-1) yielded average recoveries in the range 85-119%, with relative standard deviations less than 17%. The HPLC-MS/MS and UPLC-MS/MS multi-residue methods developed are simple, rapid and suitable for the quantification and confirmation of the 16 priority pesticides in fruit-, potato- and cereal-based baby food at 1 microg kg(-1). The major advantages of UPLC, using 1.7 microm particles, over HPLC are the speed of analysis, the narrower peaks (giving increased signal-to-noise ratio) and improved confirmation for the targeted pesticides in the analyses of baby foods.

Chromatography, High Pressure Liquid↗

PubMed2006

High-throughput quantification of lincomycin traces in fermentation broth of genetically modified Streptomyces spp. Comparison of ultra-performance liquid chromatography and high-performance liquid chromatography with UV detection.

A new separation and quantification method using ultra-performance liquid chromatography (UPLC) with UV detection was developed for detection of lincomycin traces in fermentation broth of different Streptomyces spp. A similar high-performance liquid chromatography (HPLC) protocol was simultaneously developed for comparison purposes. Both methods were validated and showed a linear range of detector response for quantification of lincomycin in concentration from 3.125 to 1000.0 microgml(-1) with correlation coefficient 0.999 and recoveries ranging from 81.5 to 89.85% with precision < or =5%. Compared with the HPLC, the UPLC method offered high sample throughput and about 10 times lower consumption of solvents. The developed assays were used for determination of lincomycin production in genetically manipulated production strain Streptomyces lincolnensis and for determination of lincomycin production after heterologous expression of lincomycin biosynthetic gene cluster in non-producing strain Streptomyces coelicolor.

Chromatography, High Pressure Liquid↗

PubMed2006

Cleaning verification assays for highly potent compounds by high performance liquid chromatography mass spectrometry: strategy, validation, and long-term performance.

A cleaning-verification assay was validated for a highly potent family of compounds utilizing a swab-sampling procedure and high performance liquid chromatography mass spectrometry (LC-MS) for separation and detection of the analytes. Due to the high potency of the compound, the LC-MS method was validated at a level of 50 ng/25 cm(2) and 50 ng/100 cm(2) (which equates to 10 ng/ml after extraction in 5 ml of sample solvent, and 3 ng/ml after correction for sampling losses). This validation exercise included recovery estimates from all drug product contact surfaces within the clinical trial manufacturing equipment, namely, stainless steel, anodized aluminum, Rilsan coated aluminum, bronze, polyvinylchloride, and Oilon. The limit of detection for the LC-MS method was determined to be less than 0.5 ng/ml, or less than 0.1 ng/cm(2), of the analyte. This method does not employ an internal standard. Long-term performance of the validated method is also reported. The precision on replicate injections of the standard prepared in the range of 3-6 ng/ml was typically better than 8.0% relative standard deviation (R.S.D.) over the course of 1 year, which resulted from 10 cleaning-verification submissions. Those results were consistent with the data obtained during method validation.

Acetates↗

PubMed1994

Outcome of cataract operations performed to permit diagnosis, to determine eligibility for laser therapy, or to perform laser therapy of retinal disorders.

Cataract operations may be recommended when retinal disease is suspected but cannot be adequately diagnosed or treated because of lens opacity. We evaluated the outcome of cataract operations performed under those circumstances. We reviewed the records of 119 patients who were examined at the Wilmer Retinal Vascular Center and within three months underwent a cataract operation. We identified 17 patients (20 eyes) who underwent a cataract operation at the recommendation of a retinal specialist, to permit diagnosis, to determine eligibility for laser therapy, or to perform laser therapy. After the cataract operation, eight (40%) of the 20 eyes were found to have a retinal disease for which laser therapy was recommended, and six (30%) of the 20 eyes underwent laser therapy that, before the cataract operation, had been impossible. These results indicate that a cataract operation may be useful when lenticular opacity prevents diagnosis or treatment in a patient with a suspected retinal disorder.

Adult↗

PubMed1983

On-line high-performance liquid affinity chromatography-high-performance liquid chromatography analysis of monomeric ribonucleoside compounds in biological fluids.

We describe an on-line multi-dimensional column chromatography system. It consists of a high-performance liquid affinity chromatography perfractionation column for cis-diol compounds and a series-connected reversed-phase high-performance liquid chromatography system for the analysis of ribonucleosides. This on-line procedure allows the rapid and direct analysis of methylated ribonucleic acid catabolites in biological fluids (serum, urine) and therefore might be useful in pathobiochemistry.

Chemical Phenomena↗

PubMed1987

New solvent system for high-performance thin-layer chromatography and high-performance liquid chromatography of gangliosides.

New solvent systems consisting of acetonitrile, isopropanol and aqueous 50 mM potassium chloride or 2.5 M ammonium hydroxide were developed for the separation of gangliosides by high-performance thin-layer chromatography. These solvent systems seem to be superior for the resolution of polysialogangliosides such as tetra-, penta- and hexasialo species, as compared to chloroform-methanol-aqueous salt systems. The order of mobility of gangliosides in the ammoniacal solvent system is GD3 greater than GD1a greater than GM1 greater than GT1b greater than GD1b as compared with GM1 greater than GD3, GD1a greater than GD1b greater than GT1b in the neutral septem. A combination of these two solvent systems provides excellent two-dimensional separations of complex ganglioside mixtures. The neutral solvent system, acetonitrile-isopropanol-aqueous 50 mM potassium chloride, can be used for the separation of underivatized gangliosides by high-performance liquid chromatography on an Aquasil SS silica gel column. Ganglioside elution can be monitored at 208 nm because of the good UV-transparency of the effluent.

Chromatography, High Pressure Liquid↗

PubMed1987

Performance evaluation of non-porous versus porous ion-exchange packings in the separation of proteins by high-performance liquid chromatography.

The performance of a non-porous, anion-exchange packing was evaluated and compared with a number of similar porous high-performance liquid chromatography packings. The non-porous columns were found to be equally efficient for proteins spanning a wide range of molecular weights, while the porous columns exhibited decreasing efficiency as the proteins became larger. The porous materials also exhibited size exclusion effects that were not seen with the non-porous materials, which partially accounts for the loss of efficiency with large proteins. When increasingly steep gradients were employed, the loss of resolution was less with the non-porous materials.

Chromatography, Gel↗