Search PubMed⌕ Search

Biomedical subjects

D A Rice

Publications and source records attributed to D A Rice.

81 records · Page 5Linked to original sources
PubMedDate not supplied

Determination of ivermectin residues in the tissues of Atlantic salmon (Salmo salar) using HPLC with fluorescence detection.

A sensitive, accurate and reproducible assay for the determination of residual concentrations of ivermectin in the tissues of farmed Atlantic salmon is described. The assay employs the clean-up of an acetonitrile extract of salmon tissue on a Bond-Elut C8 column, followed by derivatization with trifluoroacetic acid anhydride. Following separation using HPLC, 22,23-dihydroavermectin B1a is determined using fluorescence detection. The limit of detection of the assay is 1 ng per g tissue. Liver, taken from fish treated experimentally with ivermectin, was found to contain higher concentrations of 22,23-dihydroavermectin B1a than any other tissue examined. The half-life of 22,23-dihydroavermectin B1a was similar in all tissues studied, ranging from 89 to 98 degree days.

Animals↗
PubMedDate not supplied

Reminding technology for prospective memory disability: a case study.

Congenital or acquired brain damage resulting in prospective memory loss can make a child unable to become independent of care givers. This note describes a memory aid developed for a 17 year old with spina bifida and hydrocephalus who requires continual reminding to perform health maintenance tasks such as medication and feeding. Off-the-shelf computer hardware and software were used to make a reminding system that logged task completion information. Logging is a unique feature of this system, permitting review of the user's response to reminders for health or rehabilitative purposes. The system reduced the need to remind rate from > 75% to less than 10% of the time. Reminding rates returned to > 75% upon removal of the system. With the system this adolescent achieved more independent health maintenance. Weight and power requirements make this system embodiment impractical for general wheelchair use, but the technology in currently available pocket units may support the necessary functions.

Activities of Daily Living↗
PubMedDate not supplied

Analysis of the effects of astigmatism and misalignment on corneal surface reconstruction from photokeratoscopic data.

This article presents a general method of error analysis for reconstruction algorithms employed by corneal topography systems and applies this method to assess the accuracy of the Wang reconstruction algorithms. Using mathematical surface reconstructions, the method detects artifacts introduced in topographic analysis by astigmatism and misalignment. For the Wang algorithms, error introduced by astigmatism was less than 1% of the true value for surfaces with more than 10.00 diopters of astigmatism. A 1-mm translational misalignment of the analyzed surface introduced error of no more than 1.3%. Errors caused by rotational misalignment were less than 3% for misalignments of 5 degrees or less. It is concluded from the error analysis method that the Wang algorithms are sufficiently accurate for use in the analysis of corneal topography. Similar analyses need to be accomplished for the validation of commercially available corneal topography systems.

Algorithms↗
PubMedDate not supplied

A new reconstruction algorithm for improvement of corneal topographical analysis.

Accurate methods for the analysis of corneal topography are essential for the evaluation and management of corneal refractive errors. Photokeratoscopy has been used clinically to evaluate corneal shape anomalies, and methods have been developed to reconstruct the shape of the corneal surface from keratoscope photographs. However, the 2-dimensional information on the keratoscope image is insufficient for uniquely reconstructing a 3-dimensional corneal surface. Algorithms currently used make assumptions necessary for calculation, but lead to considerable error, especially at the periphery of radially aspheric corneas. This article proposes an improved algorithm that avoids some of the earlier assumptions for improved accuracy. The new algorithm was tested on both spherical and aspherical calibration surfaces. The result of this algorithm is identical to earlier methods for spherical surfaces, but the new method substantially increases accuracy in reproducing the aspherical surfaces at the cost of increased computation time.

Algorithms↗
PubMedDate not supplied

Extraction of sulfamethazine from feed samples.

The efficiency of a number of published extraction solvents for sulfamethazine in feeds was evaluated. Poor recoveries were obtained with several of the solvents when sulfamethazine was extracted from commercially pelleted feed samples. Recoveries ranged from 48 to 94%. A 75% methanol acetic acid extractant gave the best results.

Animal Feed↗
PubMedDate not supplied

Gas chromatographic-mass spectrometric detection and quantitation of lincomycin in animal feedingstuffs.

A substantially improved assay was developed for lincomycin A in animal feedingstuffs. The assay allows unambiguous quantitation of at least 0.1 ppm in feed. Lincomycin B did not interfere because of differences in both retention time and mass of the main fragment ion in electron impact (EI) spectra. The assay using single ion monitoring with EI detection would not discriminate between lincomycin A and clindamycin. The presence of the latter was easily confirmed by using gas chromatography-mass spectrometry in the chemical ionization mode. The assay for lincomycin A was linear in the range 0-40 ng applied to the gas chromatographic column. The recovery was 93.4 +/- 4.2% at 1 and 5 ppm and 86.2 +/- 5.5% at 0.1 ppm in feed. The coefficient of variation of the assay was 4.8% at both 1 and 5 ppm, and was 6.43% at 0.1 ppm.

Animal Feed↗