Use of an in vitro biotinylation technique for determination of posttransfusion viability of stored canine packed red blood cells.

OBJECTIVE: To determine posttransfusion viability (PTV) of canine RBC stored for 35 days in an additive solution, using in vitro biotinylation and technetium-99m and chromium-51 (99mTc/51Cr) labeling techniques. SAMPLE POPULATION: 6 random source, adult dogs. PROCEDURE: RBC from dogs were labeled with N-hydroxysuccinimide biotin (NHS-biotin) or 99mTc/51Cr in a crossover design. One unit (450 ml) of whole blood was collected from each dog, processed into packed RBC, and stored for 35 days in an additive solution. The process was repeated at a later date, so that each dog had 2 units stored under similar conditions. Stored autologous RBC were then labeled with either NHS-biotin or 51Cr and reinfused. When 51Cr was used, labeled cells were infused simultaneously with freshly drawn cells labeled with 99mTc. Posttransfusion viability of labeled cells was determined by dividing counts per minute (99mTc/51Cr) or percentage of cells (NHS-biotin) labeled at 24 hours by counts per minute or percentage of cells labeled after infusion. RESULTS: Mean PTV of packed RBC stored for 35 days in an additive system was 80% when determined by biotinylation, 83% as determined by 99mTc/ 51Cr, and 81% as determined by 51Cr alone. CONCLUSIONS: In vitro biotinylation provides an acceptable, nonradioisotopic means of determining PTV of stored canine packed RBC. CLINICAL RELEVANCE: NHS-biotin can be used to determine maximal storage time of canine RBC prepared for transfusion purposes.

Tumor markers and their significance in the management of breast cancer. Workshop, National Institutes of Health, March 6, 1985.

The use of molecular components from both normal and neoplastic breast tissue as markers for breast tumors has long been recognized as of major potential for breast cancer diagnosis, and has been an area of active research. Recent developments in immunological approaches have further stimulated this field by permitting new specificity in the identification and characterization of such markers. Breast tumor markers are now being explored in immunohistochemistry, radioimaging, immunodiagnosis, and even in attempts at their utilization in therapy. To bring together an update on research in this area, a workshop was held in March at the National Institutes of Health, sponsored by the advisory Breast Cancer Working Group and the Breast Cancer Program of the National Cancer Institutes (Dr. Elizabeth Anderson, Program Director) through the auspices of the Organ Systems Coordinating Center (at Roswell Park Memorial Institute, Dr. Clement Ip, Scientific Administrator). The 1 1/2 day workshop included three sessions: Circulating Tumor Markers, Breast Cancer Antigens, and Estrogen Metabolites and Estrogen-Induced Proteins.

Uridine-cytidine kinase. III. Competition between uridine and cytidine for a single enzyme.

The combined phosphorylation of uridine and cytidine by a partially purified preparation of uridine-cytidine kinase has been studied with dual-substrate kinetics. The kinetic patterns obtained are consistent with the theoretical analysis for two competing, alternate substrates interacting with a single enzyme. Thus, despite feedback regulation of the kinase by both UTP and CTP, the results allow a clear conclusion that both nucleosides are phosphorylated by the same enzyme, and probably at a single site, rather than by two closely related isozymes, each specific for one pyrimidine.