Biomedical subjects

V Van Duppen

Publications and source records attributed to V Van Duppen.

4 recordsLinked to original sources

PubMed1998

Patients with high-risk myelodysplastic syndrome can have polyclonal or clonal haemopoiesis in complete haematological remission.

The clonality of mature peripheral blood-derived myeloid and lymphoid cells and bone marrow haemopoietic progenitors from 18 females with myelodysplasia (MDS) (five refractory anaemia, RA; one RA with ringed sideroblasts, RARS; three chronic myelomonocytic leukaemia, CMML; four RA with excess of blasts, RAEB; five RAEB in transformation, RAEB-t) was studied by X-chromosome inactivation analysis. Using the human androgen-receptor (HUMARA) assay, we analysed the clonal patterns of highly purified immature CD34+ 38- and committed CD34+ 38+ marrow-derived progenitors, and CD16+ 14- granulocytes, CD14+ monocytes, CD3+ T and CD19+ B lymphocytes from peripheral blood. In high-risk patients (RAEB, RAEB-t), clonality analysis was performed before and after intensive remission-induction treatment. All patients, except one with RA, had predominance of a single clone in their granulocytes and monocytes. The same clonal pattern was found in CD34+ progenitor cells. In contrast, CD3+ T lymphocytes were polyclonal or oligoclonal in 14/18 patients. X-chromosome inactivation patterns of CD19+ B cells were highly concordant with CD3+ T cells except for two patients (one RA, one CMML) with monoclonal B and polyclonal T lymphocytes, therefore suggesting a clonal mutation in a progenitor common to the myeloid and B-lymphoid lineages or the coexistence of MDS and a B-cell disorder in these particular patients. After high-dose non-myeloablative chemotherapy, polyclonal haemopoiesis was reinstalled in the mature myeloid cells and immature and committed marrow progenitors in three of four patients achieving complete haematological remission. Therefore we conclude that most haematological remissions in MDS are associated with restoration of polyclonal haemopoiesis.

Adult↗

PubMed1993

Osmotic effects of dilution on erythrocytes after freezing and thawing in glycerol-containing buffer.

Red blood cells frozen in 1.7 M and particularly in 2.2 M of glycerol retain a high degree of integrity upon thawing as long as the dilution procedure of the cryoprotectant is slow and preferentially compensated by the addition of sorbitol. As the nonpenetrating cryoprotectant sorbitol induces initial cell shrinkage, cell swelling upon dilution of the cryoprotectants may not lead to hemolysis. However, rapid dilution of glycerol even with buffer containing up to 0.50 M of sorbitol cannot be achieved without provoking considerable hemolysis. Due to the relative slow rate at which glycerol leaves the cells, membrane damage to the younger cell populations remains considerable and is even more pronounced in the older cell groups. The dramatic osmotic changes occurring during the dilution process lead to the formation of aberrant cell populations as demonstrated by the red cell size frequency distribution curves.

Buffers↗

PubMed1991

K2- or K3-EDTA: the anticoagulant of choice in routine haematology?

The choice of K2- or K3-EDTA as the preferred anticoagulant for blood count remains controversial. We compared the effect of different concentrations of both anticoagulants on normal blood. In optimal conditions (appropriate anticoagulant concentration and measurements done between 1 and 4 h after phlebotomy), no marked differences are seen between either EDTA salt. Important discrepancies appear, however, in less optimal conditions, as often happens in day to day practice. The packed cell volume, when measured on centrifuged blood, decreases with increasing anticoagulant concentrations and this is most pronounced with the K3 salt. This phenomenon has been reported by different authors and is ascribed to shrinking of erythrocytes in an hypertonic medium. Automated instruments react in a different way, their MCV is not influenced by K3-EDTA concentrations up to ten times normal, while K2-EDTA, at high concentrations, results in a slight increase in MCV, as measured with three of the instruments. With most instruments, the accuracy of the white cell count is not markedly influenced. However, when measured with the Unipath CD 3000 all tested blood samples, taken in high K3 (but not in K2) concentrations, showed an appreciable decrease in the leucocyte count (to less than 50% of the original value, at a concentration of 15 g/l, 24 h after blood collection). Measurement of RDW and automated differentials is also influenced by the choice of anticoagulant when determinations are done in less than optimal conditions. We conclude that the choice of anticoagulant, its use at an appropriate concentration and the age of the blood sample are important matters and should be given due consideration.(ABSTRACT TRUNCATED AT 250 WORDS)

Anticoagulants↗

PubMed1990

Reticulocyte count using thiazole orange. A flow cytometry method.

Recently flow cytometry techniques have been developed to replace the microscope reticulocyte count. We used thiazole orange, a RNA binding fluorochrome, to discriminate reticulocytes from mature erythrocytes. Thiazole orange and the Retic-COUNT software package were evaluated for performance of routine analysis on different flow instruments. The applied methodology analysed 10(4) cells semi-automatically in an easily performed manner. Consistent results were obtained with dipotassium EDTA anticoagulated blood (stable for 30 h after venesection), with incubation times in thiazole orange solution ranging from 2 to 7 h at 25 degrees C. This allowed flexibility in specimen collection and storage and assay performance with no change in results. Changes of incubation temperature up to 30 degrees C had no measurable effect. The values obtained showed good linearity, precision and accuracy for normal, low and high reticulocyte counts. However interferences were observed: RBC autofluorescence, nucleated RBC, Howell-Jolly bodies, high leucocyte count, high platelet count and giant platelets, all falsely increased the number of reticulocytes. These artifacts were eliminated by software gate corrections, thus leaving less than 5% of the specimen to be reanalysed by the microscopic method. The thiazole orange flow cytometric method was determined to be a fast, reliable method for the routine clinical quantitation of reticulocytes.

Benzothiazoles↗