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Biomedical subjects

G Valet

Publications and source records attributed to G Valet.

17 recordsLinked to original sources
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↗
PubMed1979

Flow cytometry as a new method for the measurement of electrophoretic mobility of erythrocytes using membrane charge staining by fluoresceinated polycations.

The binding of FITC-labeled poly-L-ornithine and poly-L-lysine to fresh or neuraminidase treated human, rat or rabbit erythrocytes was investigated by simultaneous cell volume and cell membrane fluorescence measurements in a flow cytometer. The cell volume was converted into cell surface and the distribution curve of the fluorescence/micrometer2 cell surface was calculated from all histogram classes by a computer program. The mean fluorescence/micrometer2 cell surface as a measure of the density of the negative charges on the cell surface was directly proportional to the elctrophoretic mobility of the erythrocytes, showing that polycation binding can effectively be used for the measurement of the electrophoretic mobility of erythrocytes. The computer fitting of the experimental two parameter histograms by two dimensional Gaussian normal distributions was found to be a very efficient way of data reduction, and a good separation of overlapping cell clusters was possible even in the case of low total numbers of cells in the histogram.

Animals↗
PubMed1978

Association of low C2 and C4 serum levels with the HLA-DW2 allele in healthy individuals.

HLA typed unrelated healthy individuals (HLA-DW2 positive n = 64, and HLA-DW2 negative n = 72) were investigated for their C2 functional activity and C4 serum protein levels. For the C2 and C4 levels a bimodal distribution was found in HLA-DW2 positive and HLA-DW2 negative individuals. HLA-DW2 positive persons had a significantly higher incidence of low C2 and C4 serum levels. Our data support the concept that genes governing C2 as well as C4 serum levels are in linkage disequilibrium with the HLA-DW2 allele of the major histocompatibility complex.

Complement C2↗
PubMed1977

The trajectories of particles suspended in electrolytes under the influence of crossed electric and magnetic fields. Possible explanation of the sensitivity of organism to magnetic fields.

We observed that particles, suspended in an electrolyte and brought into crossed magnetic and electric fields of low intensities, will deviate in the central part of the electrophoresis chamber of a standard Zeiss Cytopherometer with a component vertical to both fields. The direction and magnitude, however, were sharply at variance with what would be expected by the action of the Lorentz force (EMF) on the surface of the particles. The magnitude of the deviation depends upon the magnetic and electric field strength, the ion concentration of the suspension medium and the geometry of the chamber. The movement of the particles is due to streaming of the electrolyte which is mainly caused by inhomogeneities of the electric field in the electrophoresis chamber. The magnitude of the effect is high enough to occur physiological conditions. Magneto-electrophoretic streaming might eventually act as a transducer mechanism which could explain the ability of some animals to orientate themselves in the geomagnetic field.

Electricity↗
PubMed1977

Influence of the time in culture on cellular and neuronal properties of neuroblastoma x glioma hybrid cells. With an appendix, mathematical description of the kinetics of the loss in cell volume.

The stability of a clonal mouse neuroblastoma x rat glioma hybrid cell line was examined. Cell volume and cellular content of DNA and protein were measured as functions of the passage number. They decreased with the number of serial subcultivations. Cellular volume was linearly related to cellular DNA and protein. Thus, measurements of cell volume can be used to monitor the loss of DNA from hybrid cells. After about 60 passages a stable population of hybrid cells arose, as judged by the constancy of cellular volume and by the decreased coefficient of variation of the cell volume distribution. A mathematical model for the kinetics of the simultaneous loss of cellular volume, DNA and protein is introduced. Several neuronal properties were investigated. The specific activity of the neurotransmitter enzyme choline acetyltransferase decreased by more than 50% during 56 passages. After 70 subcultivations, the hybrid cells were still capable of extending processes, action potentials could still be elicited electrically or by iontophoretic application of acetylcholine, and the cells still responded to prostaglandin E1 as they do at low passage number.

Action Potentials↗
PubMed1977

[Changes of protein metabolism after X-irradiation. III. Dose dependent changes of the protease activity, the protein and the free amino acids in the spleen, liver, blood plasma, erythrocytes, stomach- and intestinal wall and in the carcass of rats after whole body X-irradiation with 400-1000 R (author's transl)].

The protease activity against externally added haemoglobin as a substrate and the autolytic activity against the proteins of the organism were decreases in most of the organs and in the total organism on the 3rd day after irradiation. This contradicts the explanation of the protein loss by an increased protein degradation. The free amino acids in the organs and in the whole organisms are unchanged or diminished. An increase would be expected if an increased protein degradation had occured because the free amino acids are the end product of the protein degradation. The conclusion of this investigation is that other mechanisms than protein degradation are responsible for the protein loss of the organism 3-6 days after X-irradiation. The increase of the protease activity and of the free amino acids in the blood plasma from day 1-3 coincides with the end of the destruction phase in the organism between day 1-2 after irradiation. The changes of the protease activity in the erythrocytes between day 1-30 after irradiation are probably not caused by a direct effect of the radaition on the erythrocytes of the peripheral blood. They are rather the results of a transient suppression of the hematopoeitic differentiation.

Amino Acids↗
PubMed1976

[Changes of protein metabolism following irradiation. II. Protease activity, protease pattern, protein and free amino acids in the cytoplasm and cell organelles of the rat liver following 600 R whole-body irradiation].

The protease activity of cytoplasm and cell organelles of the rat liver against liver protein and hemoglobin as a substrate increases during an initial reaction phase on the first day after 600 R whole body X-irradiation. This is probably a consequence of the degradation of cellular debris. The protein, the protease activity and the free amino acids of the cytoplasm and the cell organelles decrease during the disease phase on day 3 and 4 after irradiation. The protein loss of the liver is therefore not explained by an increased protease activity. The protease activity and the free amino acids are increased in the cytoplasm and the cell organelles during the regeneration phase of the organism between day 15 and 18 after irradiation.

Amino Acids↗
PubMed1975

Electrical sizing of liver cell nuclei by the particle beam method. Mean volume, volume distribution and electrical resistance.

Electrical sizing of liver cell nuclei gives similar results as histological techniques for the mean volume, the volume distribution and the proportions of the different nuclear volume populations. The electrical method has, compared to histological technics, however, the advantage of higher rapidity and accuracy. Due to the good volume resolution of the improved electrical sizing method two populations of nuclei with different mean volumes can be distinguished in rat liver tissue besides di-, tetra- and octoploid cell nuclei. In addition to the volume distribution curves, the mean electrical resistance of isolated liver nuclei can be determined by the electrical sizing method. A newly developed micromehod provides enough cell nuclei for electrical sizing from only 10 mg liver tissue in a few minutes. This should enable the measurement of nuclear volume distribution curves of human biopsy material from the liver and gastrointestinal tract for diagnostic purposes on a larger scale.

Animals↗
PubMed1975

[Changes in protein metabolism following irradiation. 1. Activity of protease, protease pattern, protein and free amino acids in cytoplams and cell organelles of the rat spleem following 600 R whole-body X-ray irradiation].

The protease activity of cytoplasm and cell organelles of the rat spleen against spleen protein and hemoglobin as a substrate increases during an initial reaction phase of the organism on the first day after 600 R whole body X-irradiation. The alkaline proteases in the cytoplasm and the acid proteases in the cell organelles increase, whereas the protease activity against externally added hemoglobin as substrate decreases below the initial values. The protein, the protease activity and the free amino acids of the cytoplasm and the cell organelles decrease during the disease phase on day 3 and 4 after irradiation. The protein loss of the spleen is therefore not explained by an increased protease activity. Acid proteases appear in the cytoplasm which derive probably from the cell organelles. The protease activity and the free amino acids are increased in the cytoplasm and the cell organelles during the regeneration phase of the organism between day 15 and 18 after irradiation.

Amino Acids↗
PubMed1975

Mechanism of complement-induced cell lysis. Demonstration of a three-step mechanism of EAC1-8 cell lysis by C9 and of a non-osmotic swelling of erythrocytes.

Sheep erythrocytes were sized by an electrical method during lysis by antibody and complement. No volume changes were observed upon to the EAC1-8 cell intermediate. Three steps could be distinguished in the reaction of C9 with EAC1-8 cells: fixation of C9 to EAC1-8 cells, a process which proceeds also at 0 degrees C; temperature-dependent swelling of the EAC1-9 cells; and lysis of the cells. We could show that swelling of the erythrocytes induced by the complement reaction is independent of protein osmotic forces and is caused by an alteration of the erythrocyte membrane.

Animals↗
PubMedDate not supplied

Electromagnetically induced fluid streaming as a possible mechanism of the biomagnetic orientation of organisms.

The results show that both the direction and the intensity of the geomagnetic field can be sensed within the chamber of a Zeiss Cytopherometer. This suggests that electromagnetically induced fluid streaming might play a role in the perception of the geomagnetic field by organisms, although it is not clear at present in which organ the perception occurs. A basic requirement for such an organ would be an anisotropy of cells or cellular structures. The nervous system with its parallel axons, or specific cells associated with the nervous system, could thus be possible locations of the sensitivity towards magnetic fields.

Electromagnetic Fields↗
PubMedDate not supplied

Effect of pregnenolone-16alpha-carbonitrile (PCN) on rat liver.

One time i.p. injections of 5 -20 mg Pregnenolone-16alpha-carbonitrile (PCN) effects the mitotic activity of rat liver cells during a time period of 24 hours to be 20 times higher than the normal mitotic rate. This, however, does not result in an measurable increase of cell numbers and cell volumes. Furthermore, total liver DNA, RNA, protein and dry-weight remain unchanged. The injection of 7 times 10 mg PCN also results in the elevation of the mitotic rate. Return of the elevated mitotic rate to base level takes 18 days from the time the last injection of PCN was administered. During this time the number and the average volume of liver cells increases by 28% and 30%, respectively. The dry weight of liver and tetraploid nuclei increase in number, whereas RNA- and protein content remains unchanged. All parameters have reached the base line after 4 - 6 weeks following the last injection of PCN. No histological changes were observed after multiple doses of PCN that cause hyperplasia and hypertrophy of liver tissue. Hypertrophy of liver cells follows the observed hyperplasia and therefore is not expected to be the cause of the hyperplastic processes.

Animals↗