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Biomedical subjects

M A Shifman

Publications and source records attributed to M A Shifman.

23 records · Page 2Linked to original sources
PubMed1982

A colorimetric assay for releasable plasminogen activator.

We describe an equilibrium assay for measuring release of plasminogen activator form blood-vessel walls and report data from 125 individuals free of overt thromboembolic disease. Excess human plasminogen is added to the euglobulin fraction of plasma obtained before and after venous occlusion at mean systolic pressure. To measure plasmin generation in these samples, we used the chromogenic plasmin substrate D-Val-Leu-Lys-p-nitroanilide, which liberates p-nitroaniline upon cleavage. Releasable plasminogen activator in 24 subjects was determined by this colorimetric assay and by the radiocasein assay previously reported by this laboratory (Am. J. Clin. Pathol. 76,403-409, 1981), and the results were compared. The correlation coefficient was 0.97. The colorimetric assay offers several advantages over the radiocasein assay: shorter incubation (6 vs 16 h) and no preparation or quantification of a radioactive substrate and its cleavage products.

Adult↗
PubMedDate not supplied

Evaluation of a centrifugal blood cell processor for washing platelet concentrates.

A semiautomated saline wash procedure using a blood cell processor was evaluated as a technique for removing plasma from platelet concentrates. In vitro studies demonstrated 92 to 99.6 percent (mean, 96%) removal of total plasma protein (n = 30) with 84 to 97 percent (mean, 90.8%) platelet recovery (n = 28) in post-wash units. Post-wash pH values changed by +0.2 to -0.86 (mean, -0.47) (n = 30); the level of recovery from hypotonic shock was 69 to 97 percent (mean, 86%) (n = 11) of pre-wash units; weighted morphology scores decreased from a mean of 248 to 223 (n = 9). Aggregation response to arachidonic acid, collagen, and adenosine diphosphate plus epinephrine showed essentially no change following the wash procedure, and electron microscopy demonstrated slight morphologic alteration. Autologous platelets labeled with indium-111 demonstrated 43 +/- 20 percent recovery (n = 11) for washed units, compared to 41 +/- 10 percent for control unwashed units (n = 5); mean survivals were 140 +/- 41 hours (n = 11) for washed platelets and 185 +/- 28 hours for unwashed units (n = 5). Thirteen alloimmunized patients receiving 55 washed platelet concentrates demonstrated a mean 1- to 4-hour corrected count increment of 3.99 X 10(3) per microliter, compared to 3.02 X 10(3) per microliter for 77 unwashed platelet units given to the same patients. This study documents that platelet concentrates maintain viability and efficacy following a semiautomated saline wash method using the Cobe 2991 Blood Cell Processor, a technique that may be helpful for patients who require plasma-depleted platelet transfusions.

Blood Platelets↗
PubMedDate not supplied

TREACT. An expert system consultation program to aid in the diagnosis of transfusion reactions.

We have developed a rule-based, expert system consultation program, TREACT, to aid in the diagnosis of transfusion reactions. Given clinical signs, symptoms, and laboratory results, the program generates diagnoses, alerts the user when a medical director should be called, suggests follow-up actions, and makes recommendations for future transfusion. Diagnoses made by TREACT, including 121 reactions, were compared with those of the medical directors over a 6-month period. The overall diagnostic concordance between the medical directors and the program was 0.777. When this was corrected for chance association (kappa statistic), the concordance was 0.703 (p less than 0.0001), which can be interpreted on a qualitative scale as substantial agreement. The program has also been used successfully as a tool for training new technologists. Other advantages and possibilities that expert systems offer to transfusion medicine are discussed.

Diagnosis, Computer-Assisted↗