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L van Hove

Publications and source records attributed to L van Hove.

11 recordsLinked to original sources
PubMed2003

International Council for Standardization in Haematology (ICSH) recommendations for "surrogate reference" method for the packed cell volume.

The spun packed cell volume (PCV, hematocrit) is a key measurement on which are based hematology instrument calibration, reference range determination, and assignment of values to calibrators/controls. In 2001, the International Council for Standardization in Haematology (ICSH) recommended a Reference PCV method, which is fully traceable to the ICSH reference hemoglobin method. Because of its complexity, however, this method is impractical for occasional use in routine laboratories and is therefore intended primarily for use by manufacturers of capillary microhematocrit tubes, liquid calibrators, and multichannel analyzers. In response to the need for a simpler method--accessible to all routine laboratories--the ICSH offers this "Surrogate Reference" PCV procedure. It is traceable to the original ICSH Reference PCV method and is based on spun PCVs obtained using borosilicate capillary tubes with an already-known relationship to this reference procedure. This ICSH "Surrogate Reference" PCV method is substantially simpler, thus putting it within the reach of most routine hematology laboratories.

Blood Specimen Collection↗
PubMed2001

An interlaboratory study of a candidate reference method for platelet counting.

A multinational interlaboratory task force explored the important variables of platelet reference counting and developed a candidate flow cytometric reference method based on the RBC/platelet ratio. A multicenter comparison was performed to determine whether the method met the necessary criteria and was precise enough to be recommended as a new reference method. Each laboratory analyzed serial dilutions of normal specimens, stabilized material, and at least 60 patient specimens with a range of platelet counts from 1 to 400 x 10(3)/microL (1-400 x 10(9)/L). Pooled analysis of the serial dilutions showed that RBC-platelet and RBC-RBC coincidence events became negligible at sufficiently high dilutions (i.e., > 1:1,000). All laboratories demonstrated excellent intra-assay and acceptable interlaboratory precision. Two antibodies (CD61 and CD41) were used for identifying platelets and individually gave acceptable results, but in a minority of samples, staining differences were observed. The optimum method thus uses a double-labeling procedure with a final dilution factor of 1:1,000. The study demonstrated that this method meets the criteria for a reference platelet count.

Anticoagulants↗
PubMed1998

Guidelines for organisation and management of external quality assessment using proficiency testing. Expert Panel on Cytometry of the International Council for Standardization in Haematology.

This document is intended to assist towards the WHO objective that external quality assessment (EQA) schemes be established at national and/or regional levels world-wide. Quality assurance is defined as all steps taken by the director of a laboratory to ensure reliability of laboratory results and to increase accuracy, reproducibility and between-laboratory comparability. This includes the use of internal quality control procedures and participation in external quality assessment. Internal quality control provides the means for evaluation of analytic test results at the time of testing in order to decide whether they are reliable enough to be released to the requesting clinicians. EQA, on the other hand, refers to a system of retrospective and objective comparison of results from different laboratories by means of proficiency testing (PT) organised by an external agency. The main purpose is to establish between-laboratory and between-method (including between-instrument) comparability, and agreement with a reference standard where one exists. Internal quality control and EQA complement each other and must never be considered as alternatives.

Animals↗
PubMed1993

Comparative evaluation of three flow cytometers for reticulocyte enumeration.

Flow cytometric determination of reticulocytosis is progressively replacing the manual microscopic method. We evaluated three flow cytometers (Becton Dickinson FACScan, Coulter EPICS Profile II, Ortho Cytoron Absolute) for reticulocyte enumeration, using thiazole orange. For each sample, 30,000 cells were analysed. In order to comparatively evaluate the three instruments, reticulocytes were counted by manually gating the erythroid population and evaluating the gated population for fluorescence characteristics. The different instruments showed good linearity and precision. No carry-over was observed. Orthogonal regression analysis of reticulocyte counts of 100 healthy blood donor samples and 108 haematological patient samples showed a good mutual comparability between all three instruments tested, although the paired t-test showed a significant difference between the Cytoron and both the FACScan and the Profile. Despite minor statistical differences, the three instruments can be considered equivalent for daily routine reticulocyte enumeration.

Benzothiazoles↗
PubMed1993

Recommended procedures for the classification of acute leukaemias. International Council for Standardization in Haematology (ICSH).

The classification of acute leukaemias is now widely based on a combined morphological, cytochemical and immunophenotyping approach. Difficulties are frequently encountered however in reaching an acceptable degree of diagnostic concordance between different laboratories because of variations in the techniques used (in terms of methodologies, reagents and equipment) and diagnostic interpretation. The International Council for Standardization in Haematology (ICSH) convened an expert panel to consider currently available diagnostic techniques with the aim of defining a minimum cytochemical and immunological diagnostic panel that could be used as core components for the classification of acute leukemia. The proposed ICSH scheme, which attempts to balance the basic requirement for providing precise and informative diagnostic information without limiting its use to only those laboratories with sophisticated facilities, is based on three sequential levels of investigation; primary cytochemistry, intracellular phenotyping and membrane immunophenotyping. The minimum ICSH recommended cytochemistries comprise myeloperoxidase (MPO), chloroacetate esterase (ChlorE) and alpha-naphthyl acetate esterase (ANAE), and standardised methods for these cytochemistries are detailed in this communication. For cases of acute leukaemia that remain unclassified by primary cytochemistry, subsequent immunological analyses for cytoplasmic CD3, CD22, MPO and nuclear TdT are recommended. The ICSH panel considers that the use of these minimum primary cytochemical and intracellular phenotyping procedures will lead to the consistent classification of most acute leukaemias, and that the third level of investigation (membrane immunophenotyping) should be used for the purposes of confirmation, diagnostic clarification of atypical leukaemias, and the subtyping of acute lymphoblastic leukaemias (ALL). The ICSH panel also recognised that there are a number of additional technologies which can provide definitive diagnostic information, such as cytogenetics and DNA genotyping, but these were excluded from the minimum panel because of their restricted availability. While many specialised laboratories, particularly in the areas of diagnostic research, will continue to use individual investigatory protocols, it is considered that the inclusion of the ICSH scheme as core components would lead to greater consistency when comparing independent studies of acute leukemia.

Acute Disease↗
PubMed1993

A new CD43 monoclonal antibody induces homotypic aggregation of human leucocytes through a CD11a/CD18-dependent and -independent mechanism.

We describe a monoclonal antibody (mAb), designated 1.C1, that causes rapid and vigorous aggregation among normal leucocytes and among T and myeloid/monocytic cell lines. As shown by competitive binding and sequential immunoprecipitation experiments, the antigen recognized by mAb 1.C1 is a 115,000 MW sialoglycoprotein, that corresponds to the human CD43 antigen, also known as leukosialin or sialophorin. The aggregation process starts within minutes and reaches maximum level 6-18 hr after addition of the antibody. It is dependent on active cell metabolism (inhibited at low temperatures and by a mixture of the metabolic poisons azide and 2-deoxy-D-glucose), a fluid plasma membrane (inhibited by pretreatment of the cells with paraformaldehyde) and an intact cytoskeleton (inhibited by cytochalasin B). Two reference CD43 antibodies (MEM-59 and DF-T1), both binding the same or closely related sialic acid-dependent epitope as mAb 1.C1, are also capable of inducing cell clump formation. CD11a/CD18 mAb block the 1.C1-induced adhesion of resting peripheral blood leucocytes, but not of haematopoietic cell line cells. In addition, mAb 1.C1 induces homotypic aggregation of K-562 cells, which do not express members of the beta 2 integrin subfamily on their surface. These data suggest that triggering of the CD43 antigen promotes homotypic cell adhesion that is mediated by both CD11a/CD18-dependent and -independent pathways.

Antibodies, Monoclonal↗
PubMed1985

Polyoma virus-induced hemangiomas in grafts of visceral yolk sac and of embryos.

The development of hemangiomas in grafts of visceral yolk sac and embryos after in vitro infection with polyoma virus is described. These hemangiomas were shown to be positive for the polyoma tumor-specific transplantation antigen(s) and to develop as well in recipient virgin as in pregnant rats. In grafts of fetal skin or gut infected with polyoma virus neoplastic transformation was never observed.

Animals↗
PubMed1983

Yolk-sac carcinoma of extra-embryonic origin in the 129 Sv/Sl mouse.

Displacement of the visceral yolk-sac in fetectomized rats and hamsters does not only induce benign teratomas but may also lead to the development of malignant yolk-sac carcinoma. In the mouse, displacement of this extraembryonic membrane readily induces teratoma but until now yolk-sac carcinoma has never been observed in this species. In the present study we report the development of yolk-sac carcinoma in 129 Sv/Sl mice after a long latent period (8 months). The tumor is composed of visceral and parietal patterns in the primary neoplasm and in its metastases. It develops from the extra-embryonal part belonging to normal (+/+), heterozygous (Sl/+) or sterile (Sl/Sl) embryos, which proves that these yolk-sac carcinomas are not of germ-cell origin.

Animals↗
PubMed1982

Cellular events during early formation of yolk-sac-derived teratomas.

A sequential morphological study of the initial cellular events in teratoma induction by displaced visceral yolk sac after foetectomy in rats was undertaken. This study led to the observation that apart from proliferation of cells displaying definite endodermal or mesodermal characteristics, a population of poorly differentiated cells appeared some days after the surgical procedure. It is very likely that these poorly differentiated cell are stem cells from which differentiated structures originate afterwards by a process of redifferentiation. The development of granulation tissue rich in capillaries seems to enhance this process. Similarities and differences with blastema formation are discussed.

Animals↗
PubMedDate not supplied

In vitro modulation of normal and diseased human neutrophil function by pentoxifylline.

The influence of pentoxifylline on normal and diseased neutrophil function has been studied in vitro. In high concentrations pentoxifylline stimulated human neutrophil chemotaxis toward both bacterial oligopeptides and complement components. Pentoxifylline was also shown in vitro to restore the normal chemotactic capacity of neutrophils from patients with known functional defects, i.e. myelodysplastic syndromes, lazy leucocyte syndrome, juvenile parodontitis, hyper-IgE-syndrome and liver cirrhosis. Pentoxifylline was also shown to strongly inhibit the release of primary and secondary granule release of granulocytes. Moreover, pentoxifylline inhibits both basal and stimulated neutrophil adhesion to both aortic and pulmonary artery calf endothelium. The mechanism whereby pentoxifylline exerts this action is not adequately understood. While our results partially imply interference of pentoxifylline with neutrophil cyclic AMP and/or prostaglandin metabolism, down-regulation of neutrophil functional antigen (e.g. CD11, CD18) expression seems to play a key role in the observed drug effects. Finally, these results indicate that pentoxifylline may be useful in the treatment of granulocyte mediated diseases and symptoms.

Antigens, Differentiation↗