Search PubMed⌕ Search

Biomedical subjects

V Kachel

Publications and source records attributed to V Kachel.

At least 19 recordsLinked to original sources
PubMed1992

Linkage between monokine production and regulation of the negative surface charge density of human monocytes.

The regulation of the negative surface charge density of human monocytes was investigated with the help of the synthetic glycolipid analogue BAY R 1005. This compound is incorporated into the outer membrane of isolated monocytes during 24 hours of incubation. After this time the electrophoretic mobility (EM) of monocytes is unchanged at 0.95 x 10(-4) (cm2 V-1 s-1) and remains unchanged even under conditions where non-treated monocytes increase their EM up to 1.1 x 10(-4) (cm2 V-1 s-1). In addition BAY R 1005 stops differentiation of monocytes to macrophages, it triggers monokine production and abolishes monocyte suppressor activity and spreading capability. The results show that BAY R 1005 affects intracellular features. In connection with earlier investigations of the regulation of the negative surface charge density of human monocytes (1,2) the study suggests that monokine production and maintenance of the EM of monocytes are linked.

Cell Differentiation↗
PubMed1990

Eight-parameter PC-AT based flow cytometric data system.

An 8-parameter flow cytometric data system is described using an IBM-AT compatible personal computer (PC) and a commercial analog to digital conversion (ADC) board. A dedicated pulse processing interface adapts the flow cytometric pulses to the ADC board and controls the number of parameters to be taken up and the trigger conditions. The trigger thresholds are automatically held at a level immediately above the noise level. For the timing of kinetic measurements a linear voltage ramp of adjustable rise time is available. A built-in precision voltage source can be used for an overall calibration. The data system is operated by software written in assembly language. Data may be collected and processed in 1-8-parameter listmode or 1-3-parameter histogram mode. Functions are available for graphical color displays, numerical integration, multiparameter gating, and printing.

Computers↗
PubMed1990

A method for calibration of flow cytometric wavelength shift fluorescence measurements.

Recently, new fluorescent dyes have been introduced into flow cytometry which alter their spectral characteristics when changes occur in certain cell features, e.g., intracellular pH or calcium ion concentration. Such changes may be determined by measuring the fluorescence intensity ratio in two different wavelength ranges (5). Here a new method is described, which simplifies the use of steadily flowing fluids for calibration. The pulse electronics of a flow cytometer cannot process the static fluorescence signals of a streaming fluid. If, however, the exciting or emitted fluorescence light of a calibration fluid is made pulsating, the flow cytometer electronics can evaluate those pulses. The new calibration procedure uses measurement of two wavelength windows shown in a two-parameter display to generate an absolute calibration scale. Measurement of the spectral shift in calibration fluids under identical instrumental settings provides absolute values that measurements of intracellular concentrations can be referred to.

Calibration↗
PubMed1990

The increase of electrophoretic mobility and alkaline phosphatase activity are parallel events during B-cell maturation.

B-lymphocyte derived mouse myeloma cells P3X63Ag8U.1 were used to study the change of the negative surface charge density which occurs during a final maturation step of mouse and human B-cells. These cells showed a uniform EM distribution curve as long as they lived within a clone. However, when they grew in suspension at low density, a part of them increased their electrophoretic mobility (EM). Cells with enhanced EM were isolated by free flow electrophoresis. They showed lower proliferation and clone forming activity but higher alkaline phosphatase activity than cells with unchanged low EM. The study suggests that the increase of the EM and of the alkaline phosphatase activity are parallel events associated with B cell progression from the proliferative to the Ig secretion stage.

Alkaline Phosphatase↗
PubMed1988

Separation accuracy of free flow electrophoresis as proved by flow cytometry.

The separation accuracy of the free flow electrophoresis ACE 710 device was proved by immunological methods. Several cell populations of human peripheral blood were purified using physical cell isolation methods such as countercurrent centrifugal elutriation and cell electrophoresis. The purified cell fractions were treated with fluoresceinisothiocyanate-labelled antibodies. The percentages of cells in each fraction binding the antibodies of interest were determined by flow cytometry. The analyses revealed that with the help of free flow electrophoresis, given cell populations of human peripheral blood can be highly enriched and that preenrichment of minor cell populations enhances the efficacy of a flow cytometer.

Cell Separation↗
PubMed1988

The negative surface charge density is a maturation marker of human B lymphocytes.

Small resting B lymphocytes were highly enriched and completely depleted of all preactivated large B lymphocytes using countercurrent centrifugal elutriation and free flow electrophoresis. They required T lymphocytes, monocytes, and a mitogen to produce antibodies after 5 days of preincubation. Large activated B lymphocytes were obtained in cell fractions which were free of resting ones. They produced antibodies even in the absence of a mitogen. Two groups were distinguished, differing in their stage of differentiation and their negative surface charge density. The cells of one group had an electrophoretic mobility (EM) like resting B lymphocytes ranging from 0.85 to 0.99 X 10(-4) (cm2 V-1 s-1). They took 2 to 3 days of preincubation before they started to secrete antibodies. Interleukin 2 and pokeweed mitogen enhanced their antibody production capability. The cells of the other group had an EM between 0.99 and 1.13 X 10(-4) (cm2 V-1 s-1). They secreted antibodies even during the first day of incubation. The quantity of the antibodies which they produced depended only on the blood donor. It could not be influenced by a mitogen or by interleukin 2. The study shows that large B lymphocytes with high negative surface charge density are in a later maturation stage than those with lower negative surface charge density.

Antibody-Producing Cells↗
PubMed1986

On-line three-parameter data uptake, analysis, and display device for flow cytometry and other applications.

Multiparameter flow cytometric measurements are of growing interest in the study of complex features of biological cells. With state of the art instrumentation, three-parameter (3-P) data handling is relatively complicated and time consuming and the display methods are not satisfactory. As an alternative, an interactive 3-P analyzing module, Cytomic 123 is described, which displays 3-P fields during and immediately after data uptake in the form of a cubic array of 32,768 channels. The fields can be randomly rotated by hardware and software. The event frequencies in the field are primarily visualized by brightness modulation of the display dots. Additionally, the display of the field may be confined to user selected ranges of event frequencies, which may also be superposed to mixed frequency displays. A set of preprogrammed functions is available for the following tasks: (a) uptake of 3-P histograms combined with on-line control of the transducer pulses, (b) automatic uptake of a series of 2-P time correlated histograms in the cube, (c) generation and numerical evaluation of sections and projections of cube histograms, (d) interactive generation and evaluation of spatial subfields for integration, or as sorting matrix by successive erosion of section planes, or reprojection of projection windows, and (e) isometric display of sections and projections and exchange of data sets with other Cytomic modules or other data systems, especially the Cytomic 12 module, whose 2-P capabilities can be used. The module is built with low cost Z80 microprocessor eurocards. A standard oscilloscope serves as a display unit.

Computers↗
PubMed1986

Interactive multi-window integration of two-parameter flow cytometric data fields.

Integration is necessary to determine the particle content of regions of interest of flow cytometric two-parameter fields. The improved program of the Cytomic 12 analyzer (1) offers: window trace integration for relatively simple window structures. The field of interest is surrounded by an integration trace (window). Eight independent windows can be stored and successively evaluated. It also offers painted field integration for complicated window structures. The pointer or a small window is interactively moved over the structures to be integrated like the brush of a painter. The "painted field" defines the window to be integrated. Window sets and painted fields can be stored on a floppy disk. Painted fields can be added and may also serve as look up tables for sorting.

Cell Count↗
PubMed1979

Clonal hybrid cell lines expressing cholinergic and adrenergic properties.

Different cholinergic cell lines were fused with an adrenergic neuroblastoma cell line (N115-BU-8). Its fusion with a cholinergic neuroblastoma-glioma hybrid produced a "hybrid-hybrid" line containing cholinergic and adrenergic enzyme activities. Both activities were also present in subclones of this line. The presence of catecholamines in single cells was confirmed by microspectrofluorimetry. These results are discussed with respect to the possibility of a simultaneous synthesis of noradrenaline and acetylcholine in single cells. The cholinergic and adrenergic enzyme activities are influenced by cell density, by dexamethasone, and by conditioned medium.

Acetylcholine↗
PubMed1979

Fast imaging in flow: a means of combining flow-cytometry and image analysis.

The morphological identification of cells by flow cytometry is difficult. Usually cell sorting and microscopical analysis have to be used in addition. Morphological analysis is simplified by taking cell pictures from a range of particular interest immediately during flow cytometric analysis. Instruments using the video scanning technique for fluorescence imaging are slow and expensive (8, 10). Morphological information can also be obtained by transmission imaging of cells in flow, which requires shorter exposure times. Therefore a cell volume activated flow imaging device has been developed which operates at flow speeds up to 5 m/sec and which depicts transmission images of selected cells on a 16-mm film by a nsec flashlamp illumination. An electronic unit detects the particles in the optically accessible orifice, performs the pulse height analysis, triggers the flashlamp if particles are in the preselcted range of interest and feeds the film. The instrument is capable of delivering up to 150 pictures per second and works either as a flow microscope in which the cells in the preselected volume range are directly observed, or as a picture system in which the cell pictures are stored on the 16-mm film for documentation or for image analysis.

Cell Count↗
PubMed1979

Simultaneous flow cytometric DNA and volume measurements of bone marrow cells as sensitive indicator of abnormal proliferation patterns in rat leukemias.

Simultaneous flow cytometric DNA and volume analysis of normal rat bone marrow cells shows three populations of nucleated cells with different mean volume. Each of these populations proliferates in a distinct cell cycle (alpha, beta, gamma). Normally the alpha-cell cycle has the highest amplitude, the beta-cell cycle is intermediate, and the gamma-cell cycle is low. The alpha-cell cycle was very significantly depressed and the beta + gamma-cell cycle was increased in three different rat leukemias (L5222, Shay, BNML), growing on three different rat strains (BDIX, Holtzmann, Brown Norway). The two parameter analysis further revealed that cells of the beta + gamma-cell cycle were slightly hyperdiploid and hypertetraploid in leukemic animals. The decrease of the alpha-cell cycle and the hyperploidies were more sensitive indicators for the abnormal proliferation pattern than the analysis of one parameter DNA distributions which remained within normal limits in all three leukemias.

Animals↗
PubMed1977

Uniform lateral orientation, caused by flow forces, of flat particles in flow-through systems.

Recently, it was shown that the lateral orientation of sperm cells disturbs the deoxyribonucleic acid distribution measured by fluorescence in a laterally laser-illuminated flow system. The present results show how flat particles may be influenced to assume a uniform lateral orientation. This was achieved by choosing the geometrical dimensions of the hydrodynamic focusing flow path. High speed photographs of fixed chicken erythrocytes oriented in experimental chambers are presented.

Animals↗
PubMed1977

Fluvo-metricell, a combined cell volume and cell fluorescence analyzer.

A new flow through instrument that simultaneously measures cell volume (resistance pulse technique) and cell fluorescence in the same orifice will be described. The fluorescence pulses of the hydrodynamically focussed cells are picked up by the optics via the axial direction (principle of Dittrich and Goehde, Z Naturforsch 24b:360, 1969). There is no coordination problem between the fluorescence and the resistance pulses to be observed because a new type of transducer is used. The electronic system provides gating of one or two parameter histograms. Function tests are performed with the incorporated two-parameter test spectrum generator. Different examples of using the instrument in practice are shown. The volume that may be measured with an orifice of 70 micron diameter ranges between 4 and 1400 micron3 (1:350). Coefficients of variation of the fluorescence below 2% are measured.

Cytological Techniques↗
PubMed1977

Measurement of mammalian sperm deoxyribonucleic acid by flow cytometry. Problems and approaches.

Measurement of mammalian sperm deoxyribonucleic acid content is of importance in several areas of biomedical research. When measured in flow systems with orthogonal axes of illumination, flow and detection, an unexpected, distorted distribution consisting of a narrow peak with a lateral extension to the right is observed. Several lines of evidence lead to the conclusion that this effect is an optical-geometric artifact attributable to the flat shape and high index of refraction of mammalian sperm heads. This artifact disappears when an epiillumination flow system is used in which the optic axes for illumination and detection and the flow axis are all coincident. Other approaches also eliminate the artifact. The resulting coefficients of variation observed after acriflavine-Feulgen staining are 4-5%, short of the goal of 1.5% required to distinguish between human sperm bearing X and Y chromosomes and to develop a mutagen test system using mice.

Acriflavine↗
PubMed1977

A volume-activated cell sorter.

A sorter that is activated by the resistance pulses of a Coulter orifice (volume detector) has been developed. The problem arising from the distortion of the volume signals produced by the electric droplet forming and charging voltages are avoided by special shielding and grounding of the volume detector. Experiments with beads and leukocytes are described. The maximal processing rate at this time is 2000 cells/sec, the purity of sorted fractions is better than 97%, and the viability of sorted cells is better than 80%.

Cell Separation↗
PubMed1976

Basic principles of electrical sizing of cells and particles and their realization in the new instrument "Metricell".

To understand the basic events during the passage of particles through the Coulter orifice, three experiments were performed. (1) The denpendence of the volume results on the particle path has been shown by ink-colored particle beams. (2) The deformation and alignment of cells during their passage through the orifice have been photographed by a nano-second photographing technique. (3) The absolute volume evaluation of particles has been studied with model particles in enlarged model orifices of different lengths. A new compact sizing instrument, "Metricell," equipped with a particle-independent electrical calibrating system, is described.

Animals↗