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Biomedical subjects

D de Korte

Publications and source records attributed to D de Korte.

At least 37 records · Page 2Linked to original sources
PubMed2000

Low leukocyte contamination without filtration by preparation of platelet concentrates in cylindrical bags with the buffy-coat method.

BACKGROUND AND OBJECTIVES: The buffy-coat (BC) method for platelet concentrate (PC) preparation was modified in order to obtain leukodepleted PCs from single BCs without filtration. MATERIALS AND METHODS: BCs were centrifuged in cylindrical BC bags and the optimal centrifugation conditions and optimal hematocrit were determined. RESULTS: With optimal conditions, a tenfold lower leukocyte contamination was obtained compared with the conventionally shaped, wide BC bag (0.3 +/- 0.19 versus 3.0 +/- 1.71 x 10(6) leukocytes per unit; 85-ml BCs). The platelet yield obtained with the cylindrical bag did not differ significantly from the yield obtained with the conventional bag (56 +/- 16.4 versus 61 +/- 15 x 10(9) platelets per PC). Furthermore, when PCs were prepared from 100-ml BCs in cylindrical bags, a leukocyte contamination of 0.2 +/- 0.11 x 10(6) and a platelet content of 61 +/- 13.5 x 10(9) per PC were obtained. CONCLUSION: The use of cylindrical BC bags reduced the leukocyte contamination in PCs to a level required for leuko-depletion without affecting platelet recovery.

Cell Separation↗
PubMed1996

Soluble P-selectin as parameter for platelet activation during storage.

Platelet concentrates stored at room temperature deteriorate. The so-called storage lesion is characterised by morphological changes and a loss of functionality. To find an assay for early platelet activation in platelet concentrates the morphological score, beta-TG release and P-selectin expression were determined, and compared with the amount of soluble P-selectin. An ELISA was used to quantify soluble P-selectin in the storage medium. We found a significant correlation between the amount of soluble P-selectin and the percentage of P-selectin positive platelets (flow-cytometric analysis) (r = 0.7449; p < 0.0001) or the amount of beta-TG release (r = 0.6837; p < 0.0001). The morphological score also correlated significantly (negative) with the amount of soluble P-selectin (r = -0.7669; p = 0.0002). From day 0 till day 8, the amount of soluble P-selectin increased constantly from 219 +/- 49.2 ng/ml to 556 +/- 102.3 ng/ml. The detection of soluble P-selectin can be used to quantify activation of platelets during storage. The immuno-assay for soluble P-selectin is more sensitive than flow-cytometric analysis of the percentage of P-selectin-positive cells and allows earlier detection of platelet activation.

Biomarkers↗
PubMed1995

Cytidine triphosphate (CTP) synthetase activity during cell cycle progression in normal and malignant T-lymphocytic cells.

The role of cytidine triphosphate (CTP) synthetase (EC 6.3.4.2.) in the pyrimidine ribonucleotide metabolism of MOLT-3 human T-ALL cell line cells and normal human T lymphocytes during the cell cycle traverse was studied. Highly pure G1-phase samples and samples enriched in S-phase cells were obtained by counterflow centrifugation. The activity of CTP synthetase in situ, measured in pulse-chase experiments, was similar in the G1-phase and S-phase MOLT-3 cells. In contrast, in S-phase T lymphocytes, an increased activity of CTP synthetase was observed compared with G1-phase T lymphocytes. Nevertheless, the MOLT-3 samples showed an increased activity of CTP synthetase in comparison with either G1-phase or S-phase enriched samples of normal T lymphocytes. Therefore, the increased activity of CTP synthetase of MOLT-3 cells is a cell cycle-independent feature, whereas among normal T lymphocytes, the increase in activity of CTP synthetase that arises after a growth stimulus is more prominent in the S-phase.

Carbon-Nitrogen Ligases↗
PubMed1995

Pooled platelet concentrates prepared by the platelet-rich-plasma method and filtered with three different filters and stored for 8 days.

Pooled platelet concentrates (PC) prepared by the platelet-rich plasma (PRP) method were filtered with three different filters and stored for 8 days at room temperature. The effect of filtration on leukocyte contamination, platelet concentration, and the in vitro function, morphology, metabolism and activation of platelets were studied. Eight pools of 20 PRP-PC were used, each pool was split into 4 equal volumes; 3 were filtered over a PL50HF, a PL-10A and a Bio P10 filter, the 4 served as a control. After filtration, leukocyte counts exceeded 3 x 10(5) in none of the pooled PC. Platelet loss induced by filtration was about 17%. During storage, no differences in pH, PCO2, and lactate and glucose concentration were found between the filtered and the unfiltered units, nor were any differences observed between filtered and unfiltered pooled PC in aggregation upon stimulation with collagen and/or ADP, adhesion capacity to collagen in flowing blood, nucleotide content of the platelets and nucleobase concentration in the plasma, expression of activation-dependent antigens, or platelet morphology as observed by light microscopy and by the swirling effect. Selective removal of beta-thromboglobulin (22%) by the PL50HF filter was observed. Pooled PC prepared by the PRP-method can be filtered and stored for 8 days without detrimental effect on platelet function, metabolism or activation.

Blood Component Removal↗
PubMed1994

In vitro evaluation of platelet concentrates, prepared from pooled buffy coats, stored for 8 days after filtration.

BACKGROUND: Posttransfusion complications can be prevented by pretransfusion removal of donor white cells from platelet concentrate. The filtration used for this removal seems to have little effect on platelet function and activation, but more information is needed on its effect on function during subsequent long-term storage of concentrate. STUDY DESIGN AND METHODS: The effect of prestorage filtration of buffy coat-prepared platelet concentrates (PCs) on platelet function, metabolism, and activation was investigated. A pool of three PCs, each made of four buffy coats, was split into three equal volumes; two were filtered over two different filters and the third served as a control. Variables monitored immediately after filtration and during the subsequent 8-day storage period at 22 degrees C included aggregation upon stimulation with collagen and/or ADP, platelet adhesion capacity to collagen and fibrinogen in flowing blood, nucleotide content of and nucleobase release by the platelets, expression of activation-dependent antigens, and beta-thromboglobulin release by the platelets. RESULTS: No differences were observed between the PCs filtered over two different filters and the nonfiltered control PCs immediately after filtration and during storage, except for a selective removal (20%) of beta-thromboglobulin by one filter. CONCLUSION: PCs prepared from a pool of four buffy coats can be filtered and subsequently stored for 8 days (starting +/- 24 hours after whole blood collection) without detriment to platelet function, metabolism, or activation.

Antibodies, Monoclonal↗
PubMed1994

Platelets stored for 6 days in a polyolefin container in a synthetic medium with minimal plasma carry-over.

Platelet concentrates (PC) were stored for 6 days in either polyolefin (PO) or polyvinylchloride/di-(2-ethylhexyl)phtalate (PVC/DEHP) bags in 100% plasma or in a synthetic medium with 35 or 10% plasma. For all conditions studied the usual in vitro parameters were well maintained, with a pH above 6.8. In both bag types platelets can be satisfactorily stored for 6 days in a synthetic medium with minimal amounts of residual plasma. For this medium, the PO bag offers a slight advantage with respect to the preservation of platelet ATP content (> 80 versus > 70% in the PVC bags) and aggregation and adhesion capacity. The adhesion capacity increased in the PO bags, while it decreased in the PVC bags.

Acrylates↗
PubMed1994

Effect of filtration on subsequently stored platelet concentrates.

The effect of filtration on the quality of platelet concentrates (PC) during storage was investigated. Two leukocyte depletion filters (Pall PL50HF and Sepacell PL-10A) were applied to filter PC made from a pool of 4 buffy coats. For each experiment 3 PC were pooled and divided into 3 identical PC to eliminate differences between the PC. Two PC were filtered, and the third PC served as an unfiltered control. A total of 12 experiments was performed. Before filtration, volumes of the PC were 263 +/- 11.7 ml (mean +/- SD). Platelet and leukocyte counts per PC were 241 +/- 25.9 x 10(9) and 7.2 +/- 1.8 x 10(6), respectively. After filtration leukocyte counts did not exceed 5 x 10(4) in any of the PC. In the PC filtered with the Pall PL50HF the mean platelet loss was approximately 14% and with the Sepacell PL-10A, 17%. During a 9-day storage period the pH, PO2, PCO2, bicarbonate, lactate and glucose concentration and LDH release as well as the morphology, examined by the swirling effect and microscopically, were not significantly different in filtered and unfiltered units. Filtration through the 2 investigated leukocyte depletion filters for PC did not adversely affect in vitro viability of the platelets during storage.

Bicarbonates↗
PubMed1994

The platelet adhesion capacity to subendothelial matrix and collagen in a flow model during storage of platelet concentrates for 7 days.

The influence of storage of platelet concentrates (PC) on the adhesion capacity of platelets was studied. Twenty-four PC, 12 prepared by the buffy coat (BC) method and 12 by the platelet-rich plasma (PRP) method, were stored for 7 days at room temperature. On days 1, 3 and 7 of storage, the platelet adhesion capacity to subendothelial matrix (SEM) and collagen was studied in a rectangular perfusion system under flow conditions in conjunction with the platelet aggregation capacity after stimulation and the adenine nucleotide content. The platelet adhesion capacity to collagen was constant until day 3 of storage and decreased to about 80% of the starting value on day 7 of storage. The adhesion capacity to SEM, however, had already decreased on day 3 to about 75% of the value of day 1 and was even more decreased on day 7 to about 45% of the starting value. On day 1, platelets prepared by the BC method displayed a higher adhesion capacity to collagen and a higher aggregation capacity after stimulation by collagen alone or in combination with ADP, compared to platelets prepared by the PRP method. No other significant differences in adhesion or aggregation capacity were observed between the PC prepared by the two different methods. Both platelet adhesion and aggregation response decreased during storage, as did the total adenine nucleotide content. This study shows that platelet function, as measured by the aggregation and adhesion capacity, of platelets prepared by the PRP method is more severely impaired during the first 3 days of storage as compared to the function of platelets prepared by the BC method.

Blood Platelets↗
PubMed1994

The roles of uridine-cytidine kinase and CTP synthetase in the synthesis of CTP in malignant human T-lymphocytic cells.

The pattern of incorporation of [14C]uridine showed that in MOLT-3 cells an increased proportion of CTP was synthesized via CTP synthetase, compared to proliferating normal human T lymphocytes at a physiological concentration of cytidine (< 0.5 microM). Furthermore, in the proliferating normal human T lymphocytes similar patterns of incorporation of [14C]uridine were observed in the presence of the physiological concentration of cytidine and after addition of 2 microM of cytidine. In contrast, in the MOLT-3 cells after addition of 2 microM of cytidine the proportion of CTP synthesized by conversion of UTP into CTP was substantially decreased, whereas the salvage of cytidine was proportionally increased. We conclude that the reutilization of uridine is a preferred route in the synthesis of CTP for MOLT-3 cells at physiological concentrations of uridine and cytidine, whereas in proliferating normal human T lymphocytes CTP is largely synthesized through reutilization of cytidine. This difference in salvage of pyrimidine ribonucleosides may be exploited for selective chemotherapy.

Carbon Radioisotopes↗
PubMed1993

Evidence for transformation-related increase in CTP synthetase activity in situ in human lymphoblastic leukemia.

To determine the role of the enzyme CTP synthetase (EC 6.3.4.2) in the synthesis in situ of CTP in normal and in malignant lymphoblastic cells, the metabolism of radiolabeled pyrimidine ribonucleosides was studied in proliferating normal T lymphocytes and was compared with that of proliferating MOLT-3 cell-line cells and differentiated (non-proliferating) MOLT-3 cells. Both the incorporation of [14C]uridine into UTP and CTP and the incorporation of [14C]cytidine in CTP, as well as the fluxes of these labeled nucleosides through the nucleotide pools into nucleic acids, were elevated in proliferating MOLT-3 cells compared to proliferating T lymphocytes. Furthermore, the conversion of UTP into CTP was enhanced in proliferating MOLT-3 cells compared to proliferating T lymphocytes, indicating a higher activity of CTP synthetase in the leukemic cells. In non-proliferating MOLT-3 cells, the pyrimidine ribonucleotide fluxes were decreased compared to proliferating MOLT-3 cells and proliferating T lymphocytes. However, the decreased ratio of uracil/cytosine ribonucleotides that was found in proliferating T lymphocytes and proliferating MOLT-3 cells compared to non-proliferating blood lymphocytes, was preserved in the differentiated MOLT-3 cells. Moreover, although the fluxes had decreased, most CTP was still synthesized by CTP synthetase in the differentiated MOLT-3 cells. Thus, the elevated activity of CTP synthetase in MOLT-3 cells was independent of the cell growth and maturation stage. We conclude that the increased activity of CTP synthetase is associated with the process of malignant transformation in MOLT-3 cells. Therefore, CTP synthetase offers an attractive target for selective therapy in human acute T-lymphoid leukemia.

Carbon-Nitrogen Ligases↗
PubMed1992

A combined immunodeficiency with oligoclonal CD8+, V beta 3-expressing, cytotoxic T lymphocytes in the peripheral blood.

The diagnosis severe combined immunodeficiency was made in a male infant at the age of 18 wk. Known causes of severe combined immunodeficiency were excluded. The activity of total 5'-nucleotidase (E.C. 3.1.3.5) in the PBMC was found to be strongly decreased. Analysis of the peripheral blood revealed a lymphocytosis, mainly of CD8+ T cells. These lymphocytes expressed high levels of CD29, CD38, CD45RA, and MHC class II molecules but no CD25, CD26, CD27, or CD28 Ag. The cells proliferated poorly to all T cell stimulants tested and no helper activity for IgM secretion could be induced. In contrast to the poor proliferative responses, high levels of TCR-induced cytolytic activity, without lymphokine-activated killer-cell outgrowth, were induced by CD3 mAb. Analysis of TCR-beta gene rearrangements indicated that two clonal populations constituted the majority of the E-rosette+ peripheral blood fraction. Moreover, the vast majority of the CD8+ cells were found to react with a mAb to V beta 3. Polymerase chain reaction on cDNA from peripheral blood cells with primers that amplify TCR V beta elements showed, in agreement with the fluorescence data, an overrepresentation of V beta 3 but absence of usage of approximately 50% of the other V beta elements. Thus, in a severe combined immunodeficiency patient, CD8+ T cells with limited T cell receptor usage and restricted effector functions were found. The observed alterations in the 5'-nucleotidase levels may be secondary to the outgrowth of this population.

5'-Nucleotidase↗
PubMed1992

Stored platelets release nucleotides as inhibitors of platelet function.

It is well known that the function of platelets decreases progressively during storage of platelet concentrates at room temperature. To investigate this phenomenon in more detail, we have resuspended platelets that had been stored for 24 h or 72 h in fresh plasma, and we have measured the aggregation response and the ATP secretion. Conversely, the effect of plasma in which platelet concentrates (PC) had been stored for 24 h or 72 h, was tested on fresh platelets. Both the aggregation response to collagen and ADP and the collagen-induced ATP secretion of stored platelets partially recovered after incubation with fresh plasma (p < 0.05). The same parameters measured with fresh platelets incubated in stored PC-plasma were found to be significantly reduced in comparison with the response of fresh platelets in fresh plasma (p < 0.05). Finally, platelets were stored in a plasma-free medium, suitable for platelet storage and the supernatant was tested. This supernatant inhibited the function of fresh platelets in a storage time-dependent fashion. Boiling of these supernatants did not change the inhibiting capacities, whereas filtration over active charcoal did. Analysis of this supernatant revealed AMP and diadenosine tetraphosphate, which both inhibit platelet function. These data show that stored platelets release nucleotides that inhibit platelet function in a reversible manner. This phenomenon may contribute to the decrease of platelet function during storage and the recovery of platelet function after transfusion.

Adenosine Diphosphate↗
PubMed1992

[Molecular genetic studies in alpha-thalassemia].

A group of 5,000 patients, suspected of haemolytic anaemia, were investigated with molecular genetic methods for deletion types of alpha-thalassemia. In 776 (15.6%) patients a deletion of one or more alpha-globin genes was found. The same group of patients was also investigated for abnormal haemoglobins and beta-thalassaemia. In about 30% of the patients either an alpha-thalassaemia, an abnormal haemoglobin, a beta-thalassaemia, or a combination was diagnosed. In a group of patients with a haemoglobinopathy, the frequency of alpha-thalassaemia was much higher (i.e. 33%) than in individuals without haemoglobinopathy. Preselection of the patients based on the presence of microcytic erythrocytes and/or a decreased ADW0.5 of the erythrocytes gave a high incidence of false-negative and false-positive results. Therefore, haemoglobin examination should not be restricted to protein chemistry, but should include molecular genetic investigations for deletion types of alpha-thalassaemia.

Chromosome Deletion↗
PubMed1991

Loss of thrombin-induced Ca2+ mobilization in a subpopulation of platelets during storage.

Thrombin-induced changes in cytosolic free Ca2+ ([Ca2+]i) were studied in human platelets that had been stored for up to 6 days. Changes in [Ca2+]i were measured with Indo-1-loaded platelets and quantitated with two different methods: (i) measurement of the changes in total fluorescence; (ii) measurement of the [Ca2+]i changes in individual platelets in a flow cytometer, allowing the detection of non-responding platelets. The maximal concentration of [Ca2+]i after stimulation with 0.5 U of thrombin/ml decreased from 544 +/- 58 nM (mean +/- SEM, n = 6) on day 0, to 276 +/- 9 nM on day 3 and to 203 +/- 23 nM on day 6. The percentage of platelets responding to 0.5 U of thrombin/ml declined from 90 +/- 2% on day 0 to 72 +/- 4% on day 3, and to 47 +/- 8% on day 6. Nevertheless, also the responding platelets showed a decreased rise in [Ca2+]i. The study shows that during platelet storage a decrease in the rise in [Ca2+]i upon thrombin stimulation occurs. This decrease is partly due to the formation of a subpopulation of platelets that is completely unresponsive and partly due to a decreased responsiveness in the remainder of the platelets; it is not due to a gradual decline in [Ca2+]i rise in all platelets. This phenomenon provides new insight in the functional defect of stored platelets.

Blood Platelets↗
PubMed1991

Uridine fluxes in healthy proliferating T-lymphocytes, MOLT-3 T-ALL cell-line cells and differentiated MOLT-3 cells.

Incorporation of 14C-uridine into UTP and CTP and fluxes of label through these nucleotide pools to RNA and DNA were greater in MOLT-3 cells compared to T-lymphocytes. In growth-arrested, differentiated MOLT-3 cells overall incorporation of radiolabel into nucleotides and nucleic acids was lowered compared to exponentially growing cells. Turnover of UTP and CTP however, retained the profile of exponentially growing MOLT-3 cells, implicating the characteristically higher conversion of UTP to CTP is independent of the MOLT-3 cells proliferative capacities. We conclude that drugs interfering with CTP-synthetase activity are good candidates to be used as selective substances in the battle against T-ALL.

Carbon Radioisotopes↗
PubMed1991

In vitro evaluation of buffy-coat-derived platelet concentrates stored in a synthetic medium.

Human blood platelets, prepared by the buffy-coat method, were prepared and stored in different synthetic media. In a synthetic medium based on gluconate, acetate and citrate (GAC), the pH was 6.8 on day 6. This medium was chosen for further evaluation. The total platelet count and the leukocyte contamination were significantly lower in the platelet concentrates (PCs) prepared in GAC compared to PCs prepared in plasma. Platelets stored in plasma or in GAC were equally functional when tested for aggregation and adenosine triphosphate (ATP) secretion. Only stimuli that act through the arachidonic-acid pathway induced a lower platelet response in GAC. Platelet morphology was quantified by measuring the difference in light transmission during stirring at different rates in an aggregometer; no significant differences for platelets stored in GAC as compared to plasma were observed. Activation of platelets was measured by binding of monoclonal antibodies (McAb) against the Gp IIb/IIIa complex and against activation-dependent antigens (GMP 140 from the alpha-granules and a 53-kD glycoprotein from the lysosomal granules). There was no difference in binding of these McAb between platelets prepared and stored in plasma or GAC. We conclude that platelets prepared by the buffy-coat method and stored in GAC have the same in vitro qualities as platelets stored in plasma, except for the lower aggregation response by the arachidonic-acid pathway. This is probably due to an acetate-induced decrease in intracellular pH.

Adenosine Triphosphate↗