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Biomedical subjects

H Meiners

Publications and source records attributed to H Meiners.

At least 19 recordsLinked to original sources
PubMed1990

Quantitative comparison of myeloid antigens on five lineages of mature peripheral blood cells.

Five-dimensional flow cytometry was used to identify the 5 lineages of peripheral blood leukocytes simultaneously in a single cell preparation. This technique was then used to compare quantitatively the distribution of cell surface antigens on each of these lineages of cells. Neutrophils, eosinophils, basophils, lymphocytes, and monocytes were uniquely identified by correlating their forward and orthogonal light scattering signals with the amount of cell surface-bound IgE. These three cellular characteristics were combined with two additional immunofluorescence labels to create a 5-dimensional space in which each leukocyte population occupied a unique position. The relative quantities of antigens on each cell type were determined for the monoclonal antibodies CD11b, CD13, CD14, CD15, CD16, CD33, CD38, CD45, CD45R, anti-HLA-DR, and anti-Leu-8 labeled with either fluorescein or phycoerythrin. The amount of antigen was described by the mean fluorescence intensity in comparison with the background fluorescence of each cell type. The distribution of the different cell surface antigens on the 5 major leukocyte populations as well as their interdonor variation were then correlated for 10 normal donors. Since none of the antigens studied was lineage specific, it was shown that the different lineages of blood cells could clearly be identified by quantitative comparison of the antigens. This study provides the basis for discrimination between mature cells and immature stages of differentiation of leukocytes and for distinction between normal and leukemic cells.

Antigens, CD↗
PubMed1989

A rapid sample preparation technique for flow cytometric analysis of immunofluorescence allowing absolute enumeration of cell subpopulations.

A simple and rapid method was developed for immunofluorescence measurements of cells by flow cytometry which does not require washing procedures, permitting absolute enumeration of cell subpopulations. Peripheral blood cells were labeled with fluorescein and phycoerythrin conjugated monoclonal antibodies and the nucleic acid stain LDS-751. Distilled water was added following incubation to induce erythrocyte lysis by hypotonic shock. After lysis for 30 s the tonicity of the sample was increased followed by measurement on the flow cytometer. The leukocyte populations were clearly resolved in the correlation of forward and orthogonal light scattering. The immunofluorescence resolution of the labeled leukocytes was equivalent to NH4Cl and a commercial lysing preparation. Absolute number of leukocytes and percentage of leukocyte subpopulations determined with this procedure correlated well with the results obtained with a clinical hematology analyzer. Cell recovery and preservation of cellular characteristics of three different procedures for lysing the human erythrocytes were compared. The LDS-751 permitted the discrimination of intact cells from residual erythrocyte ghosts, platelets and damaged nucleated cells. A considerable loss of cells was found for both NH4Cl and commercial lysing solution; the samples prepared by NH4Cl lysing had a selective loss of lymphocyte subpopulations as compared with the other two techniques. In contrast to the two procedures in which multiple washing steps are involved, the no wash, hypotonic lysis procedure provided a means of obtaining absolute numbers of leukocyte subpopulations identified by combining light scattering and immunofluorescence characteristics with no centrifugation steps required.

Ammonium Chloride↗
PubMed1989

[Bonding of glass-ionomer cements to tooth hard tissues under various experimental conditions].

In this study the enamel- and dentin-bonding properties of two glass-ionomer cements (ChemFil-II and Ketac-Bond) were evaluated under various test conditions in vitro. The tests showed the following results: 1. ChemFil-II exhibits a significantly stronger bond to the hard tooth substances than Ketac-Bond in the short term test (the samples were stored 2 days in synthetic saliva). The stability of the bond made with ChemFil-II, however, proves in the long term test (the samples were stored 150 days in synthetic saliva) to be less than that made with Ketac-Bond. 2. Acid-conditioning of the enamel does not statistically effect a change in the stability of the bond to any significant degree. Corresponding conditioning of the dentin, on the other hand, causes a definite reduction of the bond to be obtained. 3. Deviations from the powder-liquid mixing ratio recommended by the manufacturer result in a statistically significant reduction in the bond stability, whether these involve an increase in the amount of powder or rather a decrease.

Aluminum Silicates↗
PubMed1979

[Temperature and reaction heat of elastomer casting materials].

Cross linking of the elastomer cast material is an exothermic process. The heat of reaction may produce temperature increases of several degrees centigrade in the thermically insolated samples. The heat of reaction per volume was measured; polysulfide and polyether values are approximately 10 times higher than those for silicone.

Dental Casting Investment↗
PubMed1979

[Relationship between clasp force and retention].

The relationship between the effect of retention, the clasp force, and the intersecting angle were studied experimentally under ideal conditions on phantom prostheses. The measured retention values are distinctly higher than the computed values. The reason for this discrepancy was explained. Clasp retention can be optimized if the functional formation of constructed crowns for clasp teeth is adequate.

Denture Design↗