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P F Franck

Publications and source records attributed to P F Franck.

17 recordsLinked to original sources
PubMed1999

Hereditary spherocytosis and elliptocytosis erythrocytes show a normal transbilayer phospholipid distribution.

Phosphatidylserine (PS) asymmetry was determined in red blood cells from patients with hereditary spherocytosis and elliptocytosis. No PS-exposing subpopulations were detected using the very sensitive method with fluorescently labeled annexin V. Treatment with N-ethylmaleimide or adenosine triphosphate (ATP) depletion to inactivate the flipase did not lead to formation of PS-exposing subpopulations in these cells, but elevated intracellular calcium levels did lead to extensive scrambling of the PS asymmetry. Although interactions of the membrane skeleton with the phospholipid bilayer have been suggested to stabilize the asymmetric distribution of PS across the bilayer, our data show that red blood cells with a severely damaged membrane skeleton are able to preserve asymmetry, even under conditions in which restoration of the asymmetric distribution is excluded. Moreover, the loss of membrane asymmetry in these cells requires active scrambling involving high levels of intracellular calcium as in normal cells. Our data show that the severe disorder of the membrane skeleton found in these cells does not affect the activity of flipase or scramblase, indicating that these proteins are not regulated by, nor coupled to the membrane skeleton assembly, and that possible thrombotic events in spherocytosis patients are not likely associated with altered PS topology of the red blood cells.

Annexin A5↗
PubMed1999

Serum interleukin-6 has no discriminatory role in paraproteinaemia nor a prognostic role in multiple myeloma.

We determined interleukin-6 (IL-6) levels in the serum of 212 well-defined patients with newly diagnosed paraproteinaemia and evaluated its discriminatory value and prognostic role in multiple myeloma (MM). Results were compared with serum neural cell adhesion molecule and beta-2-microglobulin, both established prognostic MM markers. Paraproteinaemia-related diagnoses were: MM (60), other haematological diseases (46), solid tumours (35), autoimmune diseases (17) and monoclonal gammopathy of unknown significance (MGUS) (54). The range of IL-6 levels in all diagnostic groups overlapped widely and did not serve as a discriminatory marker in newly diagnosed paraproteinaemia even when patients with infection or fever (42) were excluded. In MM high IL-6 levels (>/= 50 pg/ml) were not associated with a shorter survival (P = 0.24). We compared our results with 20 published studies on serum IL-6 in paraproteinaemia and/or MM. IL-6 data have to be related to the assay used (bio- or immunoassay) and to the status of MM (newly diagnosed, during therapy, progressive disease). We conclude that serum IL-6 is not specific for paraproteinaemia-related diseases and will not serve as a reliable discriminatory or prognostic marker in paraproteinaemia and MM.

C-Reactive Protein↗
PubMed1998

[The risk of a multiple myeloma in patients with paraproteinemia: a myeloma risk score developed in the region of the Comprehensive Cancer Center West].

Diagnoses in patients with paraproteinaemia are diverse; few (mostly single centre based) studies are known that describe incidence, diagnoses and follow-up in patients with paraproteinaemia. In the region of the Comprehensive Cancer Centre West in the Netherlands (population 1.6 million, 1992) a population-based registry was set up in the period 1991-1993. Patients (n = 1464; median age: 72 years; range: 16-102) were entered by clinical chemists, internists, haematologists, and pathologists. Multiple myeloma and plasmacytoma were diagnosed in 261 patients (18%), paraprotein-related haematological diseases in 159 patients (11%) and paraprotein-related internal diseases in 210 patients (14%). After bone marrow examination monoclonal gammopathy of unknown significance (MGUS) was diagnosed in 207 (14%) patients. No further diagnosis could be made in 627 (43%) patients mostly for lack of supplementary bone marrow and (or) X-ray examinations. Consequently, more than two-thirds of all patients with a newly found paraprotein did not show any sign of a haematological malignancy. Using these data a 'myeloma risk score' was developed to predict the presence of a multiple myeloma based on paraprotein type and concentration, aiding the physician in determining which patients should undergo further bone marrow and skeletal examinations.

Adolescent↗
PubMed1998

Multicenter harmonization of common enzyme results by fresh patient-pool sera.

A region consisting of 19 clinical laboratories harmonized their calibration of seven common enzymes by using fresh patient-pool sera. One of the laboratories was chosen to act as Regional Reference Laboratory (RRL). This laboratory used internationally accepted (mostly IFCC) methods at 37 degrees C, with an intralaboratory CV < or = 2.5%. First, the reference ranges of the RRL were verified by analysis of a reference population and calculation of the results by a parametric method. Next, all laboratories, including the RRL, received six patient-pool sera and analyzed them at the same time on the same date. Enzyme calibration factors at each laboratory were converted on the basis of the slope, and occasionally the intercept, of regression analysis with the RRL and the individual laboratory. Before harmonization, the interlaboratory CVs varied from 16.9% to 61.6%. After harmonization, CVs decreased to between 5.0% and 9.5%. These results proved to be reproducible over a period of more than a year. Using internationally accepted inaccuracy and imprecision criteria, the achieved interlaboratory CVs permit the use of one set of reference ranges by all participating laboratories. Certified Reference Materials were analyzed, resulting in interlaboratory CVs as low as those achieved with patient-pool sera. These materials can act as commutable reference preparations, except for creatine kinase.

Alanine Transaminase↗
PubMed1996

Faecal nitrogen determination by near-infrared spectroscopy.

The well-known Kjeldahl method for the determination of faecal nitrogen is rather complex, time-consuming and expensive. Therefore, the use of near-infrared spectroscopy in determining the amount of nitrogen in faeces has been studied. To our knowledge we are the first to present the calibration equation for the determination of nitrogen with near-infrared spectroscopy. A good correlation (r = 0.96) was found between results from near-infrared spectroscopy and the Kjeldahl method. The imprecision of both methods was comparable. Once the rather laborious calibration has been performed, near-infrared spectroscopy is shown to be a very simple and rapid method for measuring nitrogen in faeces.

Adult↗
PubMed1992

Recognition and prevention of two cases of erroneous haemocytometry counts due to platelet and white blood cell aggregation. The use of acid citrate dextrose as an auxiliary anticoagulant.

Two cases of anticoagulant-induced platelet-white blood cell aggregation are described, which resulted in erroneous haemocytometry counts. Aggregation was avoided by the use of acid citrate dextrose (ACD) as an auxiliary anticoagulant, thus enabling quantification of platelets and white blood cells.

Anticoagulants↗
PubMed1986

Does diamide treatment of intact human erythrocytes cause a loss of phospholipid asymmetry?

Diamide-treated human erythrocytes have been compared with native red cells as to the accessibility of their amino phospholipids to both phospholipase A2 hydrolysis and fluorescamine labeling. In agreement with observations by others (Haest, C.W.M., Plasa, G., Kamp, D. and Deuticke, B. (1978) Biochim. Biophys. Acta 509, 21-32), treatment of intact human erythrocytes with diamide resulted in considerably enhanced degradation of amino phospholipids upon subsequent incubation of the cells with bee venom phospholipase A2. The hydrolysis of phosphatidylethanolamine (PE) in control cells reached a plateau value at 5% after 10 min. In diamide-treated cells, on the other hand, PE hydrolysis did not level off. Contrastingly, dose-response curves recorded for the labeling of PE with the very fast reacting NH2-group-specific reagent, fluorescamine, showed identical results for both native and diamide-treated erythrocytes. In each of these two cases, a plateau was reached after approx. 15% of the PE had been labeled. These results strongly suggest that the enhanced phospholipase-A2-induced hydrolysis of amino phospholipids in diamide-treated erythrocytes may reflect a destabilization of the lipid bilayer, rather than an in situ loss of phospholipid asymmetry.

Azo Compounds↗
PubMed1985

Abnormal transbilayer mobility of phosphatidylcholine in hereditary pyropoikilocytosis reflects the increased heat sensitivity of the membrane skeleton.

We determined whether the membrane defect in hereditary pyropoikilocytosis (HPP) is associated with thermally induced changes in the lipid bilayer, the stability of which was probed by the rate of translocation of phosphatidylcholine (PC) over the two leaflets. [14C]PC was incorporated into the outer leaflet of the lipid bilayer of the intact erythrocytes using a PC-specific phospholipid exchange protein. The transbilayer equilibration of this PC was determined by measuring the time-dependent changes in its accessibility to exogenous phospholipase A2. The rate of transbilayer equilibration of PC was increased in HPP cells at 37 degrees C when compared to normal erythrocytes (rate constants, 0.07 +/- 0.02 and 0.03 +/- 0.01 h-1, respectively). A further dramatic increase in PC transbilayer equilibration was noted in HPP cells incubated at 44 degrees C (rate constant, 0.15 +/- 0.02 h-1). A similar marked acceleration in transbilayer movement of PC was also seen in normal erythrocytes when incubated at 46 degrees C (rate constant, 0.13 +/- 0.03 h-1). Despite the enhanced transbilayer mobility of PC in HPP cells when compared to normal erythrocytes, no major alteration in the asymmetric distribution could be observed when probed with phospholipase A2. Since changes in transbilayer mobility of PC and cell morphology occur in HPP cells at lower temperature than in normal red cells, it may be concluded that the enhanced thermal sensitivity of spectrin is the major factor responsible for these changes. Our results therefore support the view that the structural integrity of the skeletal network is essential for stabilization of the lipid bilayer of the red cell membrane.

Anemia, Hemolytic, Congenital↗
PubMed1985

Uncoupling of the membrane skeleton from the lipid bilayer. The cause of accelerated phospholipid flip-flop leading to an enhanced procoagulant activity of sickled cells.

We have previously reported that the normal membrane phospholipid organization is altered in sickled erythrocytes. More recently, we presented evidence of enhanced transbilayer movement of phosphatidylcholine (PC) in deoxygenated reversibly sickled cells (RSC) and put forward the hypothesis that these abnormalities in phospholipid organization are confined to the characteristic protrusions of these cells. To test this hypothesis, we studied the free spicules released from RSC by repeated sickling and unsickling as well as the remnant despiculated cells. The rate of transbilayer movement of PC in the membrane of deoxygenated remnant despiculated cells was determined by following the fate of 14C-labelled PC, previously introduced into the outer monolayer under fully oxygenated conditions using a PC-specific phospholipid exchange protein from beef liver. The rate of transbilayer movement of PC in the remnant despiculated cells was significantly slower than in deoxygenated native RSC and was not very much different from that in oxygenated native RSC or irreversibly sickled cells. The free spicules had the same lipid composition as the native cells, but were deficient in spectrin. These spicules markedly enhanced the rate of thrombin formation in the presence of purified prothrombinase (Factor Xa, Factor Va, and Ca2+) and prothrombin, indicating the exposure of a significant fraction of phosphatidylserine (PS) in the outer monolayer. This effect was not observed when the spicules in this assay were replaced by normal erythrocytes, deoxygenated native RSC, or a deoxygenated sample of RSC after repetitive sickling/unsickling. The results are interpreted to indicate that the destabilization of the lipid bilayer in sickled cells, expressed by the enhanced flip-flop of PC and the exposure of PS in the outer monolayer, occurs predominantly in those parts of the membrane that are in spicular form.

Anemia, Sickle Cell↗
PubMed1984

Modification of the erythrocyte membrane by a non-specific lipid transfer protein.

The non-specific phospholipid transfer protein purified from bovine liver has been used to modify the phospholipid content and phospholipid composition of the membrane of intact human erythrocytes. Apart from an exchange of phosphatidylcholine between the red cell and PC-containing vesicles, the protein appeared to facilitate net transfer of phosphatidylcholine from the donor vesicles to the erythrocyte and sphingomyelin transfer in the opposite direction. Phosphatidylcholine transfer was accompanied by an equivalent transfer (on a molar basis) of cholesterol. An increase in phosphatidylcholine content in the erythrocyte membrane from 90 to 282 nmol per 100 microliters packed cells was observed. Phospholipase C treatment of modified cells showed that all of the phosphatidylcholine which was transferred to the erythrocyte was incorporated in the lipid bilayer. The nonspecific lipid transfer protein used here appeared to be a suitable tool to modify lipid content and composition of the erythrocyte membrane, and possible applications of this approach are discussed.

Carrier Proteins↗
PubMed1983

Accelerated transbilayer movement of phosphatidylcholine in sickled erythrocytes. A reversible process.

The transbilayer mobility of phosphatidylcholine (PC) molecules in the membrane of homozygous reversible sickle cells (RSCs) was studied using a PC-specific exchange protein from beef liver. In deoxygenated RSCs, all of the PC present in the membrane of the intact cell is rapidly available for exchange, mediated by this protein. Since a substantial amount of the PC is present in the inner membrane leaflet of these cells, this observation implies that the PC molecules in their membranes do experience rapid transbilayer movements. To determine the actual rate of transbilayer movement of the PC, radioactive PC was introduced into the outer monolayer of oxygenated RSCs using the PC-specific exchange protein. Subsequently, the cells were incubated at 37 degrees C under oxy- and deoxygenating conditions to enable the PC to equilibrate within the bilayer. At various time intervals, samples were taken and treated with phospholipase A2, which selectively degrades the PC in the outer monolayer. Analysis of the specific radioactivities of the lyso-PC thus produced, as well as of the residual PC, enabled us to follow the fate of the radioactive PC previously introduced into the outer membrane layer. The half-time value for transbilayer equilibration of the PC in deoxygenated RSCs was determined to be 3.5 h, which is about four times lower than that for oxygenated RSCs. This increased transbilayer mobility of PC, observed in deoxygenated RSCs, is immediately restored to the normal low rate upon reoxygenation of the cells, indicating a complete reversibility of this phenomenon.

Androgen-Binding Protein↗
PubMed1982

Complete exchange of phosphatidylcholine from intact erythrocytes after protein crosslinking.

Treatment of human erythrocytes with tetrathionate or diamide resulted in extensive crosslinking of membranous and cytoskeletal proteins. Such treatment was followed by an incubation with phosphatidylcholine specific exchange protein to investigate the rate and extent of exchange of phosphatidylcholine between the erythrocytes and 14C-labeled phosphatidylcholine containing microsomal membranes or vesicles. Exchange profiles showed that the exchange of phosphatidylcholine is facilitated in treated cells when compared to control erythrocytes and, more importantly, that all of the phosphatidylcholine is exchangeable after protein crosslinking whereas in control cells only the phosphatidylcholine pool located in the outer layer of the membrane is exchangeable. These observations demonstrate that crosslinking of cytoskeletal and membraneous proteins enhances the rate of transbilayer movement of phosphatidylcholine considerably.

Androgen-Binding Protein↗
PubMedDate not supplied

Accurate platelet counting in an insidious case of pseudothrombocytopenia.

Anticoagulant-induced aggregation of platelets leads to pseudothrombocytopenia. Blood cell counters generally trigger alarms to alert the user. We describe an insidious case of pseudothrombocytopenia, where the complete absence of Coulter counter alarms both in ethylenediaminetetraacetic acid blood and in citrate or acid citrate dextrose blood samples was compounded by the fact that the massive aggregates were exclusively found at the edges of the blood smear. Non-recognition of pseudothrombocytopenia can have serious diagnostic and therapeutic consequences. While the anti-aggregant mixture citrate-theophylline-adenosine-dipyridamole completely failed in preventing pseudothrombocytopenia, addition of iloprost to anticoagulants only partially prevented the aggregation. Only the prior addition of gentamicin to any anticoagulant used resulted in a complete prevention of pseudothrombocytopenia and enabled to count accurately the platelets.

Aged↗