Biomedical subjects

E Segers

Publications and source records attributed to E Segers.

8 recordsLinked to original sources

PubMed1999

Prevalence of herds with young sows seropositive to pseudorabies (Aujeszky's disease) in northern Belgium.

In Belgium, pseudorabies in swine has been the subject of a mandatory eradication programme since 1993. From December 1995 to February 1996, a survey was conducted in the five provinces of northern Belgium to estimate the provincial pseudorabies virus (PRV) herd seroprevalence. Seven hundred and twenty randomly selected herds were included in this survey. To detect recently infected animals, only young sows were sampled. The results show that 44% of these herds had an important number of PRV-seropositive young sows. The highest herd seroprevalence was observed in West Flanders (68%), followed by Antwerp (60%), East Flanders (43%), Limburg (18%), and Flemish Brabant (8%). Assuming a diagnostic test sensitivity and specificity of 95% and 99%, respectively, and a true PRV within-herd prevalence of 43%, the overall true PRV herd prevalence was estimated to be 35%. A logistic multiple-regression revealed that the presence of finishing pigs was associated with a two-fold increase in odds of a herd being seropositive (odds ratio (OR)=2.07, 95% confidence interval (CI) = 1.31-3.26); a breeding herd size > or =70 sows was associated with a four-fold increase in odds of a herd being seropositive (OR = 4.09, 95% CI = 2.18-7.67); a pig density in the municipality of >455 pigs/km2 was associated with a 10-fold increase in odds of a herd being seropositive (OR = 9.68, 95% CI = 5.17-18.12). No association was detected between the PRV herd seroprevalence and purchase policy of breeding pigs (purchased gilts, or use of homebred gilts only).

Animal Husbandry↗

PubMed1991

Flow cytometric immunophenotyping of leukemia cells in clotted blood and bone marrow.

Immunophenotyping of leukemia cells is generally performed on cells in suspension. These suspensions are usually prepared from anticoagulated peripheral blood or bone marrow samples but when anticoagulation is suboptimal clotted samples may reach the laboratory. In this study cell suspensions were prepared from clotted blood and bone marrow samples of leukemia patients by lysis of the clots with streptokinase. The cell suspensions were then labeled with monoclonal or polyclonal antibodies and examined by flow cytometry or fluorescence microscopy. Enough cells could be isolated from small volumes of clotted blood or bone marrow aspirate to determine the immunophenotype of the cells. The morphology of the cells was well preserved and accurate identification of the cells was possible. The immunophenotypes determined on clotted samples from four patients with acute myeloblastic leukemia, five with acute lymphoblastic leukemia and two with chronic lymphocytic leukemia were identical to those established using EDTA anticoagulated samples of the same patients. When no unclotted samples are available this approach may avoid the necessity for a new sample and the concomitant delay in treatment of the patient.

Antibodies, Monoclonal↗

PubMed1991

Light microscopical detection of leukocyte cell surface antigens with a one-nanometer gold probe.

The potential of ultrasmall gold particles for the light microscopical detection of leukocyte cell surface differentiation antigens was investigated. Suspensions and cytocentrifuge preparations of peripheral blood leukocytes were first incubated with monoclonal antibodies and then with goat antimouse antibodies coupled to colloidal gold particles of 1-nanometer diameter. Cytocentrifuge preparations were made from the cell suspensions. Silver enhancement was performed on all preparations. Then they were counterstained with May-Grünwald Giemsa and examined in light microscopy. The immunostaining appeared as fine dark granules on the surface membrane of the cells. Labeling conditions were determined which gave a dense specific immunostaining and a low background. High dilutions of the ultrasmall gold probe could be used to detect all antigen expressing cells in the samples. The labeling efficiency of the IGSS method with the 1 nanometer probe was comparable to that described earlier for 5 nanometer gold particles. Lymphocyte subsets enumerated with this method in normal peripheral blood were similar to those found with immunofluorescence microscopy. We concluded that one nanometer probes do not offer a major advantage in comparison with 5 nanometer probes for the study of cell surface antigens.

Adult↗

PubMed1991

Leukemia and lymphoma immunophenotyping in cell smears with immunogold-silver staining.

The potential of the immunogold-silver staining (IGSS) technique for immunophenotyping leukemia and lymphoma cells in cell smears was examined. Peripheral blood, bone marrow aspirates, lymph node biopsy specimens, fine-needle aspirates, and biologic fluids of 83 patients with acute or chronic leukemias, non-Hodgkin's lymphomas, or Hodgkin's disease were labeled. Cell smears, cytocentrifuge preparations, or imprints were fixed, incubated with the reagents, and counterstained with May-Grünwald-Giemsa. Stable immunostaining and good morphologic characteristics allowed accurate cell identification and rapid enumeration of the positive cells. The immunophenotypes obtained with the use of 35 monoclonal antibodies with different specificities were similar to those determined by flow cytometry or immunohistochemical studies on the same samples. This IGSS method was especially useful for the examination of poor samples or complex cell suspensions with rare malignant cells. It could be an alternative to the immunoenzyme methods that generally are used for this purpose.

Antibodies, Monoclonal↗

PubMed1989

An immunogold-silver staining method for detection of cell surface antigens in cell smears.

We developed an indirect immunogold-silver staining method for detection of leukocyte cell surface antigens in cell smears. Air-dried and fixed cytocentrifuge preparations or smears of peripheral blood leukocytes were incubated with monoclonal antibodies (MAb) and colloidal gold-labeled secondary antibodies. The preparations were post-fixed and silver enhancement was performed. The smears were counterstained with May-Grunwald-Giemsa and examined in brightfield light microscopy. The morphology of the cells was well preserved. Leukocytes reacting with the MAb showed black granules on their surface membranes. The intense immunostaining and the low background allowed a rapid enumeration of the positive cells. The labeling could be detected with high sensitivity by epipolarization microscopy. This immunogold-silver staining method was used to quantify T- and B-lymphocytes and natural killer cells in buffy coat smears of normal adult blood. These lymphocyte subsets correlated well with those obtained in smears with the alkaline phosphatase-anti-alkaline phosphatase (APAAP) method and with those found by labeling of mononuclear cells in suspension with immunogold-silver staining. This immunogold-silver staining method forms a good alternative to immunoenzyme methods for study of hematologic cells. In addition, it could be a general procedure for detection of cell surface antigens in all kinds of cell smears.

Antibodies, Monoclonal↗

PubMed1988

Hematologic values and lymphocyte subsets in fetal blood.

Hematologic values and lymphocyte subpopulations were determined in normal fetal blood during the second trimester of gestation. In these samples the platelet, erythrocyte, and leukocyte counts were significantly lower than in adults. Large red blood cells with a high hemoglobin content were present. Before the twentieth week of gestation, erythroblasts made up about half of the nucleated elements. Lymphocytes formed most of the leukocytes, and their absolute numbers were comparable to those in adults. Most of the fetal blood lymphocytes expressed T- or B-cell surface differentiation antigens. The percentage of T-cells was lower and that of B-cells was higher than in the adult. A high OKT4/OKT8 ratio was present. It was due to a low percentage of OKT8-positive cells. Lymphocytes with a natural killer cell phenotype were rare. Most lymphocytes were OKT10 positive, but almost none reacted with the antithymocyte antibody OKT6. These results give additional information about the development of blood cells in early human life. They can be used as reference values for the prenatal diagnosis of hereditary or acquired anomalies of the hematologic and immunologic systems.

Fetal Blood↗

PubMed1988

Sensitive detection of immunogold-silver staining with darkfield and epi-polarization microscopy.

We evaluated the contribution of darkfield and epi-polarization microscopy to the detection of leukocyte cell surface antigens with immunogold-silver staining (IGSS). Lymphocyte cell surface differentiation antigens were labeled with monoclonal antibodies and IGSS as described for brightfield microscopy. In darkfield and epi-polarization microscopy the labeling appeared as bright spots on a dark background. The sensitivity of detection was much higher than that of brightfield microscopy. Sixteenfold higher dilutions of the monoclonal antibody could be used to detect all cells expressing the antigen in the cell suspension. However, non-specific staining was also better visualized. The latter could be reduced to a level comparable to that of brightfield microscopy only by use of weaker labeling conditions. A 25% reduction of the silver enhancement time was necessary for this purpose. However, these weaker labeling conditions also reduced the intensity of the specific staining. Therefore, the efficiency of IGSS, as detected with darkfield and epi-polarization microscopy, was only fourfold greater than that found with brightfield microscopy or that of an immunofluorescence procedure. Especially in combination with transmitted light, to improve cell identification, epi-polarization microscopy is a reliable and sensitive method for detection of immunogold-silver-labeled cell surface antigens for diagnostic and research purposes.

Antibodies, Monoclonal↗

PubMed1978

[Not Available].

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France↗