PubMed Health⌕ Search

Biomedical subjects

M L Severns

Publications and source records attributed to M L Severns.

10 recordsLinked to original sources
PubMed1992

Pattern discrimination perimetry in patients with glaucoma and ocular hypertension.

We compared the results of the pattern discrimination perimeter to the program 30-2 on the Humphrey Field Analyzer (Humphrey, Inc., San Leandro, California) in 93 consecutive patients with ocular hypertension and glaucoma and 30 control patients. In 20 patients with ocular hypertension, a significantly greater number of glaucomatous defects were noted on pattern discrimination perimetry (ten patients) than on the program 30-2 (two patients) (P less than .05, Wilcoxon signed rank test). The diversity in diagnoses found on pattern discrimination testing was not explained by age, intraocular pressure, refraction, number of glaucoma medicines, race, presence of vascular disease, optic disk status, or pupil size. In contrast, in 73 patients with glaucoma no statistical difference in the severity of diagnoses was noted between perimeters (P greater than .05, Wilcoxon signed rank test). These results suggest the potential value of pattern discrimination perimetry as a visual function test in patients with glaucoma and in defining subsets of patients with ocular hypertension not found with conventional automated perimetry.

Adult↗
PubMed1989

Computerized threshold determination for automated ABO/Rh tests.

Automated microplate blood-grouping systems rely on a pair of thresholds to determine whether reactions are positive or negative. The determination of these thresholds is a critical step in the quality control process for automated microplate blood grouping. A simple method has been developed for automatically setting these thresholds. A more sophisticated method, which required substantial computational complexity, was also tried. The more complex method did not perform better than the simple method described here.

ABO Blood-Group System↗
PubMed1988

Considerations in the use of laboratory robots: aspects of safety and accuracy.

A general-purpose laboratory robot was configured to prepare blood samples for the HBsAg and anti-HIV tests. Several issues were studied in order to eliminate problems and optimize the system. These included pipetting accuracy, intersample carryover, reagent interference, splashing and aerosol generation and user-related issues. A number of general guidelines were developed to assist others in developing and implementing systems for this and similar applications.

Evaluation Studies as Topic↗
PubMed1986

Application of robotics in blood banking.

To demonstrate the feasibility of using robots in blood banking applications several prototype systems were developed. Activities associated with sample testing and component preparation were examined. In one project, a general-purpose laboratory robot (Zymate Laboratory Automation System, Zymark, Inc., Hopkinton, Mass.) was configured to prepare samples for microplate-based ABO/Rh testing. In a second project, this same robot was configured to carry out specific steps in evaluating bar-coded labels, as part of a quality control procedure. A fluid-handling robot (Sampler 505, Tecan AG, Hombrechtikon, Switzerland) was used to prepare the dilution of serum samples for the evaluation of an anti-HTLV-III test kit. It was then configured to aspirate, dilute and dispense samples for anti-HTLV-III and HBsAg testing. This robotic system is now in field trial. The use of large industrial robots for automating component production was also considered. The key element in this design was the development of a fixture that would hold the blood bag set during the balancing, centrifugation and expressing steps. However, a fixture which was capable of performing these operations and that was equivalent in size and adaptable to a standard centrifuge bucket could not be fabricated.

Antibodies, Viral↗
PubMedDate not supplied

Cost analysis of routine laboratory testing in blood centers.

The direct costs of ABO, Rh, Du, syphilis, and antibody screening tests were investigated. Questionnaires from 58 blood centers were analyzed to compare cost-effectiveness among methods of testing and annual collection volume as well as differences in cost of the various methods of testing within the same-size center. We found that "expensive" automated equipment cannot be justified on the basis of direct costs in centers processing less than 100,000 units of blood per year and that there is a wide variation in costs among centers using the same equipment.

Blood Grouping and Crossmatching↗
PubMedDate not supplied

The status of automation and data processing in the United States blood banking community.

A survey of the extent of automation and data processing in the blood banking community was conducted by questionnaire. The likelihood that a facility had some type of automation was related to the volume of blood products produced or transfused. Facilitates that collected blood or collected and transfused blood were more likely to have automation for ABO and Rh testing than those that only transfused blood. Automation for many other blood bank tests is unavailable. Many facilities had data processing capability, which is used primarily for accounting.

Blood Banks↗
PubMedDate not supplied

A one-step Du test in microplates.

A one-step Du test, developed for use in automated microplate systems, uses anti-D with 0.6 percent dextran to potentiate the reaction. Because the washing and reagent-adding steps of the antiglobulin test are not required, the Du test can be performed in the same microplate as the ABO/Rh test. A set of reactions prepared with this technique was visually interpreted and also classified by an automated microplate ABO/Rh system. Visual interpretation of reactions resulted in a sensitivity and specificity close to those of the antiglobulin test, although the sensitivity of the test was reagent-dependent. When the automated microplate blood grouping system was used, the test was not as sensitive or as specific as the antiglobulin test, although it may be sufficient for many applications.

Autoanalysis↗
PubMedDate not supplied

A robotic system to prepare samples for HTLV-III testing.

A robotic handling system was adapted to perform the sampling and dilution steps needed in an assay to detect antibodies to the HTLV-III virus, the causative agent of AIDS. The system reduced the labor required to prepare the samples and provided standardization and accuracy in the preparation of the samples.

Antibodies, Viral↗