Biomedical subjects

P Strohm

Publications and source records attributed to P Strohm.

6 recordsLinked to original sources

PubMed1996

Empirical evaluation of the transfusion medicine tutor.

Previous research during the development of Antibody IDentification Assistant (AIDA) revealed that many medical technology students and other laboratory personnel have serious difficulties in determining the specificity of blood group alloantibodies, especially weak or multiple antibodies. Based on these previous results, AIDA was modified to provide a teaching environment for medical technology students. We report the results of a rigorous, objective evaluation of the resultant system, the Transfusion Medicine Tutor (TMT). The results show that the students who were taught by an instructor using TMT to provide the instructional environment went from 0 percent correct on a pretest case to 87 percent correct on posttests (n = 15). This increase compares with an improvement rate of 20 percent by a control group (n = 15) who used a passive version of the system with the tutoring functions turned off.

Journal Article↗

PubMed1996

Dealing with brittleness in the design of expert systems for immunohematology.

In recent years, there has been increased discussion about the potential of expert systems to support medical decision-making tasks, including applications in clinical laboratory settings. This study provides data regarding the cognitive errors that technologists make on an important problem-solving task: the identification of antibodies in a patient's blood. It explores alternative designs for expert systems developed to reduce such errors. It also evaluates the effects of these alternative designs on the ability of the users to effectively stay "in the loop," applying their own expertise and judgment while using the computer as a tool to assist with their analyses. A pilot study was conducted involving 32 certified medical technologists, which compared two alternative roles for the computer: (1) use of the computer to automatically complete subtasks upon request, and (2) use of the computer as a monitoring device to critique technologists as they completed the analyses themselves. The system design that automatically completed subtasks for the technologist induced a 29 percent increase in errors relative to the design that critiqued technologists as they completed the analyses themselves.

Journal Article↗

PubMed1995

Is the glycogen synthase analogue C1-peptide a suitable fluorescent substrate for routine measurements of protein kinase C?

We have compared a new commercially available non-radioactive protein kinase C (PKC) activity assay based on the fluorescent [A9,10K11]glycogen synthase1-11 analogue C1-peptide with a classical radioactive assay based on myelin basic protein4-14 (MBP4-14) and other substrates. The C1-peptide had lower affinity for PKC from rat brain than substrates such as MBP4-14, [S25]PKC alpha 19-31, and [A9,10K11,12]glycogen synthase1-12. The sensitivity of the C1-peptide-based assay was considerably lower than that of the MBP4-14-based assay. The C1-peptide was readily degraded in an ATP-independent manner by crude and DEAE-column chromatography-purified cytosolic extracts from rat brain, rat kidney, SK-N-MC and L929 cells. In rat kidney this degradation was not prevented by many common protease inhibitors. Phenylsepharose column chromatography separated the C1-peptide degrading activity from PKC. We conclude that the C1-peptide-based fluorescent PKC assay is applicable to highly purified PKC preparations but has low sensitivity and is not applicable to crude extracts due to substrate degradation.

Amino Acid Sequence↗

PubMed1991

Determining the significance of anti-Kl in hemolytic disease of the newborn (HDN).

Anti-K1 is capable of causing severe hemolytic disease of the newborn (HDN), but few cases are seen due to the low frequency of the antigen. A total of 1,215 pregnancies from 1962 to 1989 were reviewed. There were 404 non-anti-D clinically significant antibodies, of which 103 (25%) were anti-K1. Anti-K1 was detected in nine of the women at delivery, of whom two had antigen-positive infants who were clinically unaffected. Antigen typing was done on 64 of the 85 fathers. Forty-seven were K - 1 and 17 were K1,2; 21 were unavailable. Antibody titers were done on the mothers in the latter two groups. Women with titers <32 were followed by titration studies; all delivered clinically unaffected infants, four of whom were K:1. Women with titers >32 had amniocentesis performed for optical density values (AOD450) or, after November 1987, were offered an alternative test, cordocentesis, to type the fetus and to do hemoglobins if the fetus was antigen-positive. Two women had severely affected infants requiring multiple intrauterine transfusions starting at 20-23 weeks. Six others delivered antigen-positive infants who did not require transfusions, although all had positive direct antiglobulin tests (DAB). We conclude that titration studies are reliable tools to evaluate anti-K1 sensitization when the titer is <32. Cordocentesis can detect antigen-negative fetuses, which then reduces the need for titrations and amniocentesis.

Journal Article↗

PubMed1986

A bone marrow transplant with an acquired anti-Le(a): a case study.

A patient with aplastic anemia received an ABO incompatible bone marrow transplant (BMT) from an HLA identical sibling. Weekly HLA antibody screens were performed as part of the BMT protocol. At the time of transplant, a hemolytic anti-Le(a) was detected in the Le (a-b-) donor. The Le (a-b+) recipient had no red cell or LCT antibody. A hemolytic anti-Le(a) was detected in the recipient on day 8, but no LCT reactivity was noted at this time. On day 15, the LCT panel demonstrated reactivity with 9 of 50 panel cells without apparent HLA specificity. Graft vs. host disease (GVHD) was present on the skin at this time. The dose of cyclosporin A was increased, but by day 20 the GVHD worsened and the LCT titers increased to 8. This strong reactivity was noted only in the Le (a+) panel members (12/50) and was neutralized with commercial Lewis substance. On day 34 there was no evidence of GVHD, but the lymphocytotoxic anti-Lea continued to be present. The patient began experiencing renal and gastrointestinal difficulties by day 48, and expired on day 60. In renal transplants the kidneys retain their Lewis type and secrete Lewis substance in the urine. In our experience BMT patients retain their Lewis type regardless of the type of the donor. The Lewis system has been linked to renal allograft rejection, and Lewis antigens may function as transplantation antigens in BMT patients as well. In addition, lymphocytotoxic Lewis antibodies can mask other significant HLA antibodies and must be identified when screening patients in need of plateletpheresis products.

Anemia, Aplastic↗

PubMed1985

RED: a red-cell antibody identification expert module.

We describe a software module in an expert system RED, which interprets data related to red cell antibody identification. There are three portions to this module: the problem-solving component, which incorporates the knowledge required for antibody identification as a hierarchy of programs. The programs in the hierarchy organize within themselves small pieces of knowledge represented in the form of production rules, which are capable of making judgments concerning a specific hypothesis; an intelligent data base for storage of patient data, red cell attributes, and test results; the "overview critic" portion, which combines the atomic hypotheses judged favorably by the antibody programs into a unified judgment concerning the case. Overview makes the decision to terminate processing with a conclusion about which antibodies are actually present and what specific further tests need to be performed to resolve any remaining ambiguities.

Artificial Intelligence↗