Biomedical subjects

P Rebulla

Publications and source records attributed to P Rebulla.

129 records · Page 8Linked to original sources

PubMedDate not supplied

Platelet support of patients with hematological malignancies.

The most significant advances in platelet transfusion therapy for oncology-hematology patients can be summarized as follows: 1) prophylaxis versus treatment of hemorrhage. Usual practice is based on hemorrhage prophylaxis. Debate is still open on the transfusion trigger, which is traditionally set at 20 x 10(9)/L platelets: some authors suggest it could safely be decreased in stable patients to 10 or 5 x 10(9)/L platelets; 2) preparation of platelet concentrates. Platelets prepared from platelet-rich plasma or buffy-coats obtained from multiple bag donations should be used as the first-choice for all patients, while apheresis platelets, which have a significantly higher cost of production, should be reserved for patients refractory to random donor support. The final choice, however, of a prudent strategy must also consider logistic aspects, such as product availability, distance from site of production to site of use, etc; 3) leukocyte reduction. Filtration is the method of choice to prepare leukocyte-reduced platelets. Leukocyte-reduced platelets can be used to prevent transmission of CMV in selected patient groups for whom this is indicated. When leukocyte reduction is used for the prevention of NHFTR, it should be performed with fresh platelets and reserved for patients developing more than 1 reaction. Routine leukocyte reduction for all oncology-hematology patients cannot be recommended at this time, in the absence of definitive information on the cost-effectiveness of this approach; 4) quality control. Studies are under way to check whether evaluation of the swirling phenomenon, that is produced by good quality platelets when inspected with the naked eye against a strong light source is a useful and inexpensive test for quality control; 5) correction of refractoriness to random donor platelet support. Effective platelets for refractory patients can be obtained through HLA typing and/or platelet cross-matching. Although HLA typing can be very effective, cross-matching seems to be equally effective, simpler and less expensive.

Hematologic Diseases↗

PubMedDate not supplied

A micro colorimetric assay using cryopreserved monocytes to evaluate antibody-mediated red cell-monocyte interaction.

BACKGROUND AND OBJECTIVE: A number of in vitro assays based on the interaction of red cells with monocytes have been used to determine the clinical significance of red cell antibodies. When used in our laboratory, one of these assays (the monocyte-macrophage phagocytosis assay-MMPA), was very time consuming and showed great variability. METHODS: We set up a monocyte phagocytosis colorimetric assay (MPCA), using standard microtiter plate wells coated at 37 degrees C for 1 hour with monocytes from healthy donors. After washing the wells to remove non-adherent monocytes, test red cells are added to the wells. Sensitized red cells bind to the monocytes, which are lysed after incubation to measure red cell phagocytosis. This is done by hemoglobin detection in the lysate through reaction with o-phenylenediamine and absorbance evaluation with a colorimeter. The results are expressed as the phagocytosis index (PI), which is calculated with the following formula: PI = [1-(A450 unsensitized red cells/A450 sensitized red cells)] x 100. In this study we determined: the source of MPCA variability; the precision of MPCA results; the correlation between MMPA and MPCA results; the MPCA reference values and the MPCA and MMPA execution times. RESULTS: MPCA variability depended largely on the monocyte source. The smallest variation coefficient of the results of replicate assays (19-21%) was found using pooled, cryopreserved monocytes. When performed with a pool of cryopreserved monocytes from 10 subjects, the SD of PI values obtained in replicate assays showed little variation (11-13) over the range of anti-D concentrations tested (from 18.75 to 300 ng/mL). A linear correlation coefficient r of 0.96 was obtained when MPCA and MMPA were performed in parallel, and the 95th centile of PI reference values determined with red cells of 40 non-transfused surgical patients free of irregular red cell antibodies was 7. MPCA execution time was 56% of that needed to perform MMPA. INTERPRETATION AND CONCLUSIONS: These studies show that MPCA is an easy and reproducible assay which allows objective and automated evaluation of red cell phagocytosis.

Colorimetry↗

PubMedDate not supplied

Use of a rapid method for genotyping human platelet antigen systems in neonatal alloimmune thrombocytopenia.

We applied a polymerase chain reaction-sequence specific primer (PCR-SSP) method developed by other researchers to study 4 families of newborns with neonatal alloimmune thrombocytopenia (NAITP) in which serology had provided inconclusive human platelet antigen (HPA) typing data. This method allowed for the identification of the newborn HPAs which were incompatible with their respective mothers. They were HPA-2b, -1b, -3a, and -5b. This PCR-SSP is a useful tool for improving the ability to identify the incompatible HPA in NAITP.

Adult↗