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B Houwen

Publications and source records attributed to B Houwen.

At least 19 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↗
PubMed2000

Flow cytometric method for enumeration and classification of reactive immature granulocyte populations.

We developed a flow cytometric method for the enumeration and classification of nonmalignant immature granulocytes (IG). In this study, IG are defined as most immature (IG stage 1: promyelocytes and myelocytes) and as more mature (IG stage 2: metamyelocytes). Blood specimens from 46 patients with documented infectious or inflammatory disease and known presence of IG (by routine manual microscopy) were analyzed. For a reference manual differential count, we used a 400 white blood cell (WBC) differential and separated granulocytes into promyelocytes and myelocytes combined, metamyelocytes, and included band cells in the mature, segmented neutrophil population. The flow cytometric method is based on three-color staining of whole, anticoagulated blood with CD45-PerCP, CD16-FITC, and CD11b-PE-labeled monoclonal antibodies and a three-step gating procedure. The flow cytometric results were confirmed by cell sorting and microscopic evaluation of the sorted cells. A total of 10,000 events, excluding debris, were recorded per specimen and IG stage 1 (CD16-/CD11b-), IG stage 2 (CD16-/CD11b+), and mature neutrophils (CD16+/CD11b+) were categorized. Regression and correlation between flow cytometric IG and the manual differential showed y = 1.34x + 0.95, r(2) = 0.86 for IG stages 1 and 2 combined versus promyelocytes, myelocytes, and metamyelocytes. For IG stage 1 versus microscopic counts of promyelocytes and myelocytes, the results were y = 1.53x + 1.24, r(2) = 0.76; for IG stage 2 versus manual metamyelocyte count, y = 0.77x + 0.21, r(2) = 0.58. Reproducibility of the flow cytometric method showed a coefficient of variation (CV) of 6.8% for all IG combined compared with a CV of 50.2% for manual differential IG count (based on a routine 100 WBC count). Samples were found stable at least 12 h at 25 degrees C and at least 48 h at 4 degrees C for flow cytometry. After staining and lysing, the sample was stable for at least 120 min at room temperature. We analyzed samples from patients with myelodysplastic and myeloproliferative disease separately. We found that CD16- mature neutrophils falsely elevated the flow cytometric IG count. Similar results were obtained in blood from patients treated with granulocyte-colony stimulating factor (G-CSF). Although this restricts the use of the method somewhat, we believe that this flow cytometric method is useful for enumerating reactive IG, as well as for evaluating automated methods for IG identification by hematology analyzers.

Flow Cytometry↗
PubMed1999

New rapid flow cytometric method for the enumeration of nucleated red blood cells.

BACKGROUND: Nucleated red blood cells (NRBC) in blood specimens compromise the automated white blood cell (WBC) count on most hematology analyzers. This makes it necessary to correct the WBC count by subtracting separately counted NRBC by manual microscopy. In addition, it is clinically important to establish the non-physiological presence of NRBC in blood specimens because of their association with significant hematological and non-hematological disease. Unfortunately, manual microscopic methods lack sensitivity, specificity and reproducibility required for both. METHODS: We have developed a new, rapid flow cytometric method for the detection and enumeration of NRBC, based on two-color staining with anti-CD45-fluorescein-isothiocyanate (CD45-FITC) and propidium iodide (PI). EDTA anticoagulated blood samples are incubated for 30 min with CD45-FITC, followed by 30 sec acid-hypotonic lysis, containing PI and subsequent addition of an alkaline-hypertonic solution. The samples are thus ready for flow cytometric analysis. RESULTS: The method typically yields up to four populations, (1) red blood cell (RBC) ghosts, debris, lyse-resistant RBC, reticulocytes and platelets, (2) CD45(+) WBC unstained by PI, (3) CD45(+) WBC stained by PI, and (4) CD45(-)/PI(bright) NRBC. Manual microscopic reference NRBC counts of 25 patient specimens showed excellent correlation with flow cytometric NRBC determinations (y = 0.943x+0. 66; r(2) = 0.982). Performance for precision showed a mean coefficient of variation (CV) for the flow cytometric method of =10%, with a mean CV for manual NRBC counts of 40%. CONCLUSIONS: We conclude that this method is suitable for NRBC counting in peripheral blood specimens with improved performance in terms of accuracy, reproducibility when compared to manual microscopic methods.

Adult↗
PubMed1997

The spun micro-haematocrit and mean red cell volume are affected by changes in the oxygenation state of red blood cells.

In this study we examined the effects of in vitro oxygenation and deoxygenation on the spun micro-haematocrit (packed cell volume or PCV) and the electronically measured mean cell volume (MCV) and haematocrit (Hct) of red blood cells. Because PCV and/or MCV and Hct are being used for calibration of haematology analysers, it is important that their potential variability caused by outside factors is known. We found that these parameters did vary with the oxygenation state of the erythrocyte and conclude that the effect is most likely caused by a combination of water shifts due to intracellular carbamate and bicarbonate formation, and conformational changes in haemoglobin. The results of the study have implications for whole blood calibration and for short term imprecision assessments of automated haematology analysers. To ensure consistent results, we recommend that blood specimens be fully oxygenated before reference work or reproducibility studies of MCV, Hct and/or PCV are attempted.

Carbon Dioxide↗
PubMed1994

A method to examine the need for duplicate testing of common coagulation tests.

A statistical protocol for evaluating the need for duplicate coagulation testing was developed. It requires at least 32 sets of duplicate prothrombin times or partial thromboplastin times over the expected range of results. In addition to the statistical procedures, clinical evaluation of the duplicates is required.

Humans↗
PubMed1994

Flow cytometric reticulocyte analysis. Multiinstitutional interlaboratory correlation study.

Reticulocyte analysis by flow cytometry offers precision and sensitivity greater than those of conventional morphologic methods and permits derivation of a reticulocyte maturity index. However, interlaboratory variability has not yet been reported. The authors analyzed 310 samples at eight sites using 11 instruments over a 4-month period to examine intermethod and interlaboratory variabilities. Stains included thiazole orange, ethidium bromide, and auramine O. Instruments included models by Coulter, Becton Dickinson, TOA Medical Electronics, and Ortho Diagnostics. The coefficient of variation (CV) among all sites and methods on these samples varied as a function of the reticulocyte percentage, ranging from a mean CV of 69% for samples with < .5% reticulocytes to 24.1% for those with > 2.5% reticulocytes. The best performance was observed with the TOA R-1000 dedicated reticulocyte analyzers, with a mean CV of 18.4% for samples with < .5% reticulocytes and 4.6% for samples with > 2.5% reticulocytes. The reticulocyte maturity index showed comparable intersite precision, with a mean CV of 16% for samples with > 2.5% reticulocytes with multipurpose flow cytometers and a mean CV of 7.3% with the TOA R-1000 instruments. Interclass correlations among all sites ranged from .79 to .99 for the reticulocyte counts and .41 to .88 for the reticulocyte maturity index. The authors conclude that flow cytometric reticulocyte analysis is more precise than manual reticulocyte analysis. With greater automation of this methodology, further interlaboratory standardization of reticulocyte counts and the reticulocyte maturity index can be achieved.

Adolescent↗
PubMed1994

Reticulocyte maturity as an indicator for estimating qualitative abnormality of erythropoiesis.

AIMS: To determine the maturity of reticulocytes in patients with anaemia as a result of various haematological disorders including those with qualitative abnormalities such as ineffective erythropoiesis or dyserythropoiesis. METHODS: The number of mature reticulocytes was measured with flow cytometry in venous blood samples from 122 patients with haematological disorders and 100 healthy controls. Reticulocytes were classified into three categories by the fluorescence intensity of auramin O staining: low fluorescence ratio (LFR), medium fluorescence ratio (MFR), and high fluorescence ratio (HFR). Immature reticulocytes were determined as the aggregate of MFR and HFR (%). RESULTS: The mean (2SD) number of immature reticulocytes in 100 normal subjects was 9.0 (7.0)%. Significantly high mean values of immature reticulocytes with a normal or reduced reticulocyte count were shown in 90 patients with dyserythropoietic or ineffective erythropoietic conditions, such as acute myeloid leukaemia (AML) (n = 37), myelodysplastic syndrome (MDS) (n = 35), aplastic anaemia (AA) (n = 8), or megaloblastic anaemia (MA), (n = 6). Reticulocyte ratios returned to normal after successful treatment of patients with AML (n = 10) and MA (n = 3). However, high percentages of immature reticulocytes with increased reticulocyte counts were consistently observed in patients with enhanced erythropoiesis such as those with acquired autoimmune haemolytic anaemias (AIHA) (n = 4) or acute blood loss (ABL) (n = 4). Reticulocyte maturity was within the normal range in patients with reduced erythropoiesis such as occurs in chronic renal failure (CRF) (n = 11), or in iron deficiency anaemia (IDA) (n = 13). CONCLUSIONS: The evaluation of reticulocyte maturity with total reticulocyte count seems to be clinically useful for estimating the qualitative impairment of erythropoiesis, and so could help differentiate haematological disorders.

Acute Disease↗
PubMed1990

Random errors in haematology tests: a process control approach.

Random errors are usually not detected by classic quality-control methods, because these can occur not only during the analytical procedure itself, but during any step of the entire process of generating test results: from patient specimen collection till the final result is being charted. Random errors therefore require a variety of methods for prevention and detection. Process control enables the analysis of the causes and categories of random error, while it also assists in the design and implementation of methods for prevention and detection. In this paper the various aspects of such an approach are discussed. Among the suggested measures that will reduce the frequency of random error are: specimen labels with machine-readable codes, application at the site of specimen collection; instrument interfacing to a laboratory computer system; and streamlining of data entry. Recommendations for random error detection systems include parameter-flagging criteria, internal consistency checks of test results, and delta checking. These measures need to be part of a systems approach to be most successful, and will result in a significant reduction, although not in a complete elimination, of both the incidence of random errors and the frequency with which test results containing random errors will be reported.

Blood Specimen Collection↗
PubMed1990

In vivo administration of recombinant interleukin-2 induces granulocyte-macrophage colony formation in a murine system.

The in vivo administration of recombinant interleukin-2 (rIL-2) in humans has led to anemia, thrombocytopenia, and eosinophilia. In an attempt to evaluate the effects of the in vivo administration of rIL-2 on murine bone marrow, we administered rIL-2 to C57BL/6 female mice i.p. three times a day at doses ranging from 10,000 to 100,000 U for 10 days; we then harvested blood and bone marrow from these animals every other day and performed the following analyses: White blood cell count, red blood cell count, hemoglobin concentration, histogram analysis of nucleated cell volume, manual differential counts, and in vitro colony-forming assays for granulocytes and monocytes (CFU-GM). The administration of rIL-2 induced an overall increase in the total white blood cell count that was dose-dependent for its appearance and overall number. This increase was secondary to an increase in monocytes and granulocytes but not to a change in lymphocyte number. Myeloid proliferative activity measured by CFU-GM revealed a biphasic pattern of activity. An early proliferation at 2 days was not followed by lymphocytosis. However, a second peak of proliferation at 6 days was associated with peripheral blood granulocytosis and monocytosis. After rIL-2 was discontinued on day 10, the CFU-GM activity returned to normal by days 16-18. These results suggest that the in vivo administration of rIL-2 may play an important role in the regulation of hematopoiesis.

Animals↗
PubMed1989

Double autologous bone marrow transplantation for acute myelogenous leukemia in a patient treated for Hodgkin's disease.

A 30-year-old man developed acute myelogenous leukemia nearly 3 years after treatment of Hodgkin's disease with radiation and three chemotherapy combinations. Remission was induced with one cycle of high-dose Ara-C therapy. Three cycles of consolidation chemotherapy were given. The patient then had two autologous bone marrow transplants, the first after conditioning with 5 Gy total body irradiation, the second after Melphalan 140 mg/m2. The procedures were well tolerated, although hematological reconstitution was very slow after the second autotransplant. The patient has been disease-free for over 4 years. Such patients may be more vulnerable to transplant-related complications because of their previous exposure to chemotherapy and radiation, which may damage several organs including the bone marrow. This report demonstrates that patients with secondary acute myelogenous leukemia may tolerate a double autotransplant procedure and achieve durable remissions.

Adult↗
PubMed1989

Differentiation-linked expression of the plasminogen activator inhibitor type-2 gene in the human HL-60 promyelocytic cell line.

HL-60 is a human promyelocytic cell line which was found to be capable of differentiating toward a macrophage-like or granulocyte-like phenotype. Histochemical analysis demonstrated that incubation of cells in the presence of phorbol myristate acetate (PMA) or 1,25-dihydroxyvitamin D3 induced varying degrees of monocytic differentiation, while incubation in the presence of retinoic acid (RA) or dimethyl sulfoxide (DMSO) induced granulocytic differentiation. The differentiation induced by PMA, RA, and to a lesser extent DMSO, was accompanied by the induction of plasminogen activator inhibitor expression. mRNA analysis of control and PMA-induced cultures revealed the induction of a 2-kb message in treated cells which hybridized with a PAI-2-specific oligonucleotide probe. This is consistent with the literature concerning the expression of PAI by macrophages and granulocytes. No hybridization was detected with a PAI-1 specific probe. Expression of PAI by cells of hematopoietic origin appears to be associated with differentiation or stimulation of committed cells. Furthermore, PAI-2 expression by HL-60 cells is not restricted to one specific hematopoietic lineage. Since other cells of hematopoietic origin such as platelets express PAI-1, future studies using pluripotential cell lines could provide information on the initial events of lineage commitment and gene expression.

Cell Differentiation↗
PubMed1989

The use of inference strategies in the differential diagnosis of microcytic anemia.

A new expert system developed on a Macintosh personal computer using a commercially available artificial intelligence shell was compared with four different discriminant functions (DFs) for the differentiation of microcytic anemia into etiologic categories. Several databases were used with a different composition but all contained at least some samples from thalassemic individuals and from patients with iron deficiency anemia. The DFs analyzed were those proposed by England and Fraser, Green and colleagues, Mentzer, and by Shine and Lal. None of the databases performed satisfactorily when used singly, whereas very high false-positive rates were obtained by one of them. The diagnostic efficiency was somewhat improved by combining several DFs. An expert system using an artificial intelligence "shell" with an "interference engine" was developed using cluster analysis and a set of learning examples. The input necessary for the system to achieve a conclusion consists of MCV, RBC, and RDW as well as a statement as to whether the patient has anemia. Based upon the values of these parameters, the expert system will give an "advice" regarding the probabilities for thalassemia, iron deficiency, and/or other probabilities such as previous transfusions, anemia of chronic disease, laboratory error, etc. In a prospective trial, the system functioned with an accuracy of better than 85%.

Anemia, Hypochromic↗
PubMed1989

Treatment of advanced Hodgkin's disease with high dose melphalan and autologous bone marrow transplantation.

Twenty patients with Hodgkin's disease which had relapsed at least once after chemotherapy, were treated with melphalan 140-220 mg/m2 i.v. followed by reinfusion of non-cryopreserved autologous bone marrow. Four patients (20%) remain alive and disease-free 28, 45, 52, and 96 months after treatment respectively. There were no treatment-related deaths. This appears to be the only reported series of patients treated with a single agent in this situation. The results are comparable to those achieved by multi-agent regimens with autologous or allogeneic bone marrow transplantation.

Adult↗
PubMed1988

Hairy cell leukemia and anti-leukocyte common antigen.

Thirty-three bone marrow biopsies from 15 patients with hairy cell leukemia (HCL) were evaluated morphologically and immunohistochemically by use of the peroxidase-antiperoxidase technique to demonstrate reactivity for leukocyte common antigen (LCA). Hairy cells in all biopsies showed a distinctive and characteristic pattern for LCA, which decorated the periphery of the cytoplasm but that left most of the cytoplasm and the nucleus unstained. Anti-LCA was particularly helpful in highlighting focal or subtle leukemic infiltrates. Hairy cells in biopsies from three patients had, on routine morphologic examination, a spindled and sarcomatoid appearance, but these too were strongly LCA positive. Treatment regimens were variable: five patients had splenectomy and received chemotherapy; five patients had splenectomy alone; and four patients had chemotherapy alone. Seven patients received interferon, and one patient received no treatment. In those six patients who had multiple biopsies as part of follow-up examinations, hairy cells as identified by anti-LCA were continuously present. Often in significant numbers, and were usually underestimated or not identified by routine examination. In those patients who received chemotherapy, qualitative alterations in the LCA reaction of hairy cells were observed.

Adult↗
PubMed1986

Bone marrow transplantation for acute monocytic leukemia following the treatment of Hodgkin's disease.

A 32-year-old woman developed acute monocytic leukemia within a year of treatment for Hodgkin's disease with chemotherapy and radiation. Residual leukemia was present in the bone marrow after two induction courses of high-dose Ara-C. She received a bone marrow transplant from an HLA- and DR-identical sister and remains in complete remission more than 2 years after transplantation. Only one other instance of a remission greater than 2 years after transplantation for secondary acute leukemia could be found in the literature. Although bone marrow transplantation may be carried out successfully in these patients, it is possible that they may be more vulnerable to transplant-related complications because of their previous exposure to chemotherapy and radiation. Only further study can clarify this matter and determine the best time for the procedure and which regimen should be used.

Adult↗